Patent Description:
<CIT> discloses a bonded abrasive article comprising a bond material and abrasive particles, wherein the bond may comprise <NUM>-<NUM> wt% alumina and optionally comprises <NUM>-<NUM> wt% lithium oxide.

Bonded abrasive articles, such as abrasive wheels, can be used for cutting, grinding, or shaping various materials. Performance of bonded abrasive articles can vary when used in different applications. For instance, a grinding wheel suitable for grinding a carbon steel workpiece may not provide satisfactory performance for grinding a chrome steel workpiece. The industry continues to demand improved bonded abrasive articles that can be suitable for more than one application.

The following description in combination with the figures is provided to assist in understanding the teachings provided herein. The following disclosure will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise.

The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

Embodiments are directed to bonded abrasive articles with improved versatility, which can allow the same abrasive articles to be suitable for grinding and shaping various types of workpieces under different grinding conditions (e.g., wheel speeds or material removal rates). According to an embodiment, the abrasive articles can include an inorganic bond material, such as a vitreous bond material, and abrasive particles contained within the bond material. The bond material can include a particular ratio of a content of alumina (Al<NUM>O<NUM>) to a content of lithium oxide (Li<NUM>O) based on weight, which can help to form an improved microstructure, which may in turn facilitate improved versatility of the abrasive articles.

The abrasive articles described in embodiments herein can be suitable for various grinding operations including for example, centerless grinding, cylindrical grinding, crankshaft grinding, various surface grinding operations, bearing and gear grinding operations, creepfeed grinding, and various toolroom applications.

<FIG> includes a flowchart illustrating a process of forming an abrasive article in accordance with an embodiment. As illustrated, at step <NUM>, the process can be initiated by forming a mixture including abrasive particles and a bond material or bond precursor material.

In an embodiment, the abrasive particles can include a material selected from the group of oxides, nitrides, carbides, borides, silicates, superabrasives, minerals, monocrystalline, polycrystalline, amorphous, or a combination thereof. For example, the abrasive particles can include SiC. In another embodiment, the abrasive particles can include alumina (Al<NUM>O<NUM>), such as microcrystalline alumina (e.g., sol-gel alumina), nanocrystalline alumina, fused alumina, or the like. In another embodiment, the abrasive particles can include white alumina. In a particular embodiment, a majority of the abrasive particles can include alumina, and more particularly, the abrasive particles can consist essentially of alumina.

In accordance with an embodiment, the abrasive particles can include unagglomerated abrasive particles, agglomerated abrasive particles, or a combination thereof. In a particular embodiment, a majority of the abrasive particles can be unagglomerated abrasive particles, or more particularly, the abrasive particles can consist essentially of unagglomerated abrasive particles. According to further embodiment, the abrasive particles can have a certain average particle size (D50), which can facilitate improved formation and/or performance of the abrasive article. For instance, the abrasive particles can have an average particle size (D50) of at least <NUM> microns, such as at least <NUM> micron, at least <NUM> microns, at least <NUM> microns, at least <NUM> microns, at least <NUM> microns, at least <NUM> microns or even at least <NUM> microns. Still, in another non-limiting embodiment, the abrasive particles can have an average particle size (D50) of at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns or at most <NUM> microns. It will be appreciated that the abrasive particles can have an average particle size within a range including any of the minimum and maximum values noted above.

The bond material or bond precursor material may include a powder material that may form the bond material of the finally-formed abrasive particle. In one embodiment, the bond precursor material can include a frit. In another embodiment, the bond precursor material can include an inorganic material, such as a ceramic material, a carbonate, minerals, inorganic compounds, or any combination thereof. As used herein, a reference to a ceramic can include a composition including at least one metal element and at least one non-metal element. For example, a ceramic may include material such as oxides, carbides, nitrides, borides, and a combination thereof. In still another embodiment, the bond precursor material can include an oxide-based composition, which may include some content of silica (i.e., silicon dioxide), boron oxide, alumina (i.e., aluminum oxide), lithium oxide, sodium oxide, potassium oxide, iron oxide, titanium oxide, magnesium oxide, calcium oxide, or the like. Contents of the bond material of the finally-formed bonded abrasive body are described in more details later in this disclosure. The composition of the bond precursor material and the bond material of the finally-formed bonded abrasive body can be substantially the same (i.e., <NUM>% or less difference in any one of the components between the precursor bond material and bond material of the finally-formed bonded abrasive body) or essentially the same (i.e., <NUM>% or less difference in any one of the components between the precursor bond material and bond material of the finally-formed bonded abrasive body).

The bond precursor material can have a particular melting temperature that may facilitate suitable formation and performance of the abrasive article. In at least one embodiment, the bond precursor material can have a melting temperature that is at least <NUM>, such as at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM>. Still, in one non-limiting embodiment the melting temperature of the bond precursor material can be at most <NUM>, such as most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. It will be appreciated that the melting temperature can be within a range including any of the minimum and maximum temperatures noted above. For instance, the melting temperature of the bond precursor material can be in a range including at least <NUM> and at most <NUM> or in a range including at least <NUM> and at most <NUM>.

In some applications, secondary particles, such as a filler material, secondary abrasive particle, or both can be added to the mixture including the bond precursor material and abrasive particles. The filler material can be distinct from the abrasive particles and may have a hardness less than a hardness of the abrasive particles. The filler material may provide improved mechanical properties and facilitate formation of the abrasive article. The filler material may also be distinct from compositions contained within bond precursor material. In at least one embodiment, the filler material can include various materials, such as fibers, woven materials, non-woven materials, particles, minerals, nuts, shells, oxides, alumina, carbide, nitrides, borides, organic materials, polymeric materials, naturally occurring materials, and a combination thereof. In particular instances, the filler material can include a material such as wollastonite, mullite, steel, iron, copper, brass, bronze, tin, aluminum, kyanite, alusite, garnet, quartz, fluoride, mica, nepheline syenite, sulfates (e.g., barium sulfate), carbonates (e.g., calcium carbonate), cryolite, glass, glass fibers, titanates (e.g., potassium titanate fibers), zircon, rock wool, clay, sepiolite, an iron sulfide (e.g., Fe<NUM>S<NUM>, FeS<NUM>, or a combination thereof), fluorspar (CaF<NUM>), potassium sulfate (K<NUM>SO<NUM>), graphite, potassium fluoroborate (KBF<NUM>), potassium aluminum fluoride (KAlF<NUM>), zinc sulfide (ZnS), zinc borate, borax, boric acid, fine alundum powders, P15A, bubbled alumina, cork, glass spheres, silver, Saran™ resin, paradichlorobenzene, oxalic acid, alkali halides, organic halides, and attapulgite.

In certain instances, the secondary particles can include secondary abrasive particle including a material such as an oxide, a carbide, a nitride, a boride, a carbon-based material (e.g., diamond), an oxycarbide, an oxynitride, an oxyboride, or any combination thereof. In certain instances, the secondary abrasive particle can be particularly hard, having for example, a Mohs hardness of at least <NUM>, such as at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>. According to one embodiment, the secondary abrasive particles can include a superabrasive material. The secondary abrasive particles can include a material selected from the group of silicon dioxide, silicon carbide, alumina, zirconia, flint, garnet, emery, rare earth oxides, rare earth-containing materials, cerium oxide, sol-gel derived particles, gypsum, iron oxide, glass-containing particles, and a combination thereof. In another instance, secondary abrasive particle may also include silicon carbide (e.g., Green 39C and Black 37C), brown fused alumina (57A), seeded gel abrasive, sintered alumina with additives, shaped and sintered aluminum oxide, pink alumina, ruby alumina (e.g., 25A and 86A), electrofused monocrystalline alumina 32A, MA88, alumina zirconia abrasives (NZ, NV,ZF), extruded bauxite, cubic boron nitride, diamond, abral (aluminum oxy-nitride), sintered alumina (Treibacher's CCCSK), extruded alumina (e.g., SR1, TG, and TGII), or any combination thereof. The secondary abrasive particles may be diluent grains, having a hardness less than the abrasive particles, but still harder than filler materials that may be present in the abrasive article. In still other instances, the secondary abrasive particles may include shaped abrasive particles, which unlike crushed grains, each of the shaped abrasive particles can have a precise and substantially similar shape relative to each other.

Formation of the mixture can include forming a dry or wet mixture. It may be suitable to create a wet mixture to facilitate suitable dispersion of the abrasive particles within the bond precursor material. Moreover, it will be appreciated that the mixture can include other materials, including for example additives, binders, and any other materials known in the art to facilitate formation of a mixture to create a green product prior to formation of the abrasive article. In at least one embodiment, the mixture can be essentially free of a pore former.

Referring again to <FIG>, after forming the mixture, the process can continue at step <NUM> forming the mixture into a green body. The process of forming the mixture into a green body can include pressing, molding, casting, cutting, printing, curing, depositing, drying, heating, cooling, or any combination thereof.

Referring again to <FIG>, after forming the green body at step <NUM>, the process can continue at step <NUM> by forming the green body into the finally-formed abrasive article. In certain instances, the process of forming the green body and the process for forming the finally-formed abrasive article can be combined, such that the mixture is converted directly to the finally-formed abrasive article. Suitable processes for forming the finally-formed abrasive article can include pressing, molding, casting, cutting, printing, curing, depositing, drying, heating, cooling, or any combination thereof.

In accordance with an embodiment, the process can include applying a temperature to the mixture or the green body to form the finally-formed abrasive article. In one particular embodiment, the temperature can be sufficient to form a vitreous bond material from the bond precursor material. In another embodiment, heating can be performed at a forming temperature of the bond material, such as at most <NUM>, such as at most <NUM>, at most <NUM>, at most <NUM> or even at most <NUM>. In another instance, heating can be performed at a temperature of at least <NUM>, such as at least <NUM>, or at least <NUM>. It will be appreciated that the forming temperature can be within a range including any of the minimum and maximum values noted above. The forming temperature can be at or above the melting temperature of the bond precursor material.

Heating can be conducted in a suitable atmosphere. In an embodiment, the mixture can be heated in a non-oxidizing atmosphere, such as a nitrogen-rich atmosphere, and more particularly, in an atmosphere that consists essentially of nitrogen. In another embodiment, a non-oxidizing atmosphere can include one or more noble gases. Still, in another embodiment, heating can be performed in an ambient atmosphere (i.e., air).

After forming, the bonded abrasive body may be incorporated into an abrasive article. It will be appreciated that the bonded abrasive body may have any suitable size and shape as known in the art and can be incorporated into various types of abrasive articles to form a bonded abrasive article. For example, the bonded abrasive body can be attached to a substrate, such as a hub of a wheel to facilitate formation of a bonded abrasive grinding wheel.

According to an embodiment, the abrasive article can include a body including a vitreous bond material extending throughout the body. <FIG> includes a scanning electron microscopic image of a cross section of a bonded body <NUM>. As noted in <FIG>, the abrasive article can have a body <NUM> in the form of a bonded abrasive including abrasive particles <NUM>, bond material <NUM> in the form of bond bridges joining the abrasive particles <NUM>, and pores <NUM> extending between the bond material <NUM> and abrasive particles <NUM>.

The bonded abrasive body may include a certain content of the bond material that may facilitate improved performance of the abrasive article. In accordance with an embodiment, the body including at least <NUM> vol% bond material for a total volume of the body. In still other embodiments, the bonded abrasive body can include at least <NUM> vol% bond material, such as at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% bond material for a total volume of the body. In yet another non-limiting embodiment, the body of the bonded abrasive can have at most <NUM> vol% bond material for the total volume of the body, such as at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% bond material for a total volume of the body. It will be appreciated that the bonded abrasive body can have a bond material content within a range including any of the minimum and maximum percentages noted above.

In an embodiment, for a certain amount of bond material, the body can include a particular number of bond bridges that can facilitate improved performance of the abrasive article. In an aspect, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include at least <NUM> bond bridges, such as at least <NUM> bond bridges, such as at least <NUM> bond bridges, or at least <NUM> bond bridges. In another aspect, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include at most <NUM> bond bridges, such as at most <NUM> bond bridges, at most <NUM> bond bridges, or at most <NUM> bond bridges. In a further aspect, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including any of the minimum and maximum values noted herein. For instance, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including at least <NUM> and at most <NUM>. It is to be understood that when the body includes the bond material in a range that is in the range from <NUM> vol% to less than <NUM> vol%, the body can include any number of bond bridges noted herein. For instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% or in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>.

As used herein, the number of bond bridges in the body can be determined as follows. A cross section of the body of an abrasive tool can be polished using a Buehler machine with Al<NUM>O<NUM> aqueous solution followed by diamond paste. High-contrasting scanning electron microscope (i.e., Hitachi TM <NUM> Plus) images of the entire cross section are taken under the magnification of 30X. Usually at least <NUM> to <NUM> images are needed for the entire cross section. Following the instructions of Bruker Quantax <NUM> EDS, silicon mapping is performed on the high-contrasting images to illuminate the bond material and obtain images similar to <FIG>. Images demonstrating only the bond material are also provided by Bruker Quantax <NUM> EDS and used for subsequent analysis with ImageJ (i.e., version of <NUM>. 51q, published on September18th, <NUM>), provided by the National Institutes of Health, to determine the number of bond bridges. All the images of the entire cross section are analyzed to establish statistical confidence of the number of the bond bridges. Newer versions of ImageJ that can allow the analysis to be performed in the same manner as follows can also be used, such as the version of <NUM>. 52e published on July <NUM>th, <NUM>.

Analysis is performed in the <NUM>-bit setting, and the threshold can be set such that the percentage of the highlighted areas is as close as possible (e.g., to the extent allowed by ImageJ) to the actual content (vol%) of the bond material in the body. Images similar to <FIG> can then be obtained and used for determining the number of bond bridges. <FIG> includes an image of a cross section of the body of a conventional abrasive article sample, C1, and a cross section of the body of a representative sample, S1, of an embodiment. Bond bridges are shown in black and abrasive particles and pores are not visible. The average of the total number of bond bridges of all the analyzed cross-sectional images is used as the number of bond bridges of the body in this disclosure. For instance, if <NUM> images are analyzed and have N1, N2, N3, N4 bond bridges, respectively, the number of the bond bridges of the body is N, wherein N=(N1+N2+N3+N4)/<NUM>.

In a further aspect, when the body includes the bond material from at least <NUM> vol% to less than <NUM> vol%, the body can include at least <NUM> bond bridges, such as at least <NUM> bond bridges, at least <NUM> bond bridges, at least <NUM> bond bridges, at least <NUM> bond bridges, at least <NUM> bond bridges, at least <NUM> bond bridges, or at least <NUM> bond bridges. In a further aspect, when the body includes the bond material from at least <NUM> vol% to less than <NUM> vol%, the body can include at most <NUM> bond bridges, at most <NUM> bond bridges, at most <NUM> bond bridges, at most <NUM> bond bridges, or at most <NUM> bond bridges. In a further aspect, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including any of the minimum and maximum values noted herein. For instance, when the body includes the bond material in a range from at least <NUM> vol% to less than <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including at least <NUM> and at most <NUM> bond bridges. It is to be understood that when the body includes the bond material in a range that is in the range at least <NUM> vol% to less than <NUM> vol%, such as in a range from <NUM> vol% to <NUM> vol% or in a range from <NUM> vol% to <NUM> vol% or in a range from <NUM> vol% to <NUM> vol% or in a range from <NUM> vol% to <NUM> vol%, the body can include any number of bond bridges noted herein. For instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>. In another instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>. In still another instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>. In still another instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>.

In a further aspect, when the body includes the bond material of at least <NUM> vol%, the body can include at least <NUM> bond bridges, such as at least <NUM> bond bridges, or at least <NUM> bond bridges. In a further aspect, when the body includes the bond material of at least <NUM> vol%, the body can include at most <NUM> bond bridges, at most <NUM> bond bridges, at most <NUM> bond bridges, or at most <NUM> bond bridges. In a further aspect, when the body includes the bond material of at least <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including any of the minimum and maximum values noted herein. For instance, when the body includes the bond material of at most <NUM> vol% for the total volume of the body, the body can include bond bridges in a range including at least <NUM> and at most <NUM> bond bridges. It is to be understood that when the body includes the bond material in a range that is in the range of at least <NUM> vol%, such as in a range from <NUM> vol% to <NUM> vol% or in a range from <NUM> vol% to <NUM> vol%, the body can include any number of bond bridges noted herein. For instance, when the body includes the bond material in a range from <NUM> vol% to <NUM> vol% for the total volume of the body, the body can include any number of bond bridges noted herein, such as in a range from at least <NUM> to at most <NUM> or in a range from at least <NUM> to at most <NUM>.

The bond material of the abrasive article may have a particular bond chemistry that may facilitate improved manufacturing and performance of the abrasive article. For example, the bond material can be a vitreous material including oxides, such as alumina (Al<NUM>O<NUM>), an alkali metal oxide, an alkaline earth metal oxide, boron oxide, silicon oxide, or any combination thereof. In one embodiment, the bond material can be essentially free of zircon (ZrSiO<NUM>). In another embodiment, the bond material can have an amorphous phase. In one particular embodiment, the bond material can be essentially free of a crystalline phase. In another particular embodiment, the bond material can consist essentially of a vitreous material. As used herein, the term, essentially free of, when used in reference to a component of the body or a component of the bond material, such as a compound, is intended to mean the component is present in a content of less than <NUM> wt%, and may be less than <NUM> wt% for the total weight of the body or the bond material.

In accordance with an embodiment, the bond material can include alumina (Al<NUM>O<NUM>). The alumina can be present in a certain content that can facilitate improved formation and performance of the abrasive article. For instance, the content of alumina (Al<NUM>O<NUM>) can be greater than <NUM> wt% for a total weight of the bond material, such as at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% for a total weight of the bond material. In another instance, the bond material can include alumina (Al<NUM>O<NUM>) of at most <NUM> wt% for a total weight of the bond material, such as at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for a total weight of the bond material. Moreover, the content of the alumina (Al<NUM>O<NUM>) can be within a range including any of the minimum and maximum values disclosed herein. For instance, the bond material can include alumina (Al<NUM>O<NUM>) in a range from greater than <NUM> wt% to <NUM> wt%, or in a range from <NUM> wt% to <NUM> wt% or in a range from <NUM> wt% to <NUM> wt%.

According to an embodiment, the bond material can include lithium oxide (Li<NUM>O). The lithium oxide (Li<NUM>O) can be present in a certain content that can facilitate improved formation and performance of the abrasive article. For instance, the content of lithium oxide (Li<NUM>O) can be at most at most <NUM> wt% for the total weight of the bond material or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for a total weight of the bond material. Alternatively or additionally, the content of lithium oxide (Li<NUM>O) of at least <NUM> wt% for the total weight of the bond material or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% for a total weight of the bond material. Moreover, the content of lithium oxide (Li<NUM>O) can be within a range including any of the minimum and maximum values disclosed herein. For instance, the bond material can include lithium oxide (Li<NUM>O) in a range from at least <NUM> wt% to at most <NUM> wt%.

In accordance with another embodiment, the bonded abrasive body can include a particular ratio of a content of alumina relative to the content of lithium oxide, such that the bond material includes a ratio (Al<NUM>O<NUM>/Li<NUM>O) based on weight percent. Such a ratio may facilitate improved formation and performance of the abrasive article. In one embodiment, the ratio (Al<NUM>O<NUM>/Li<NUM>O) can be at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. In another embodiment, the ratio (Al<NUM>O<NUM>/Li<NUM>O) can be greater than <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM>. Moreover, the ratio (Al<NUM>O<NUM>/Li<NUM>O) can be in a range including any of the minimum and maximum values noted herein. For instance, the ratio (Al<NUM>O<NUM>/Li<NUM>O) can be in a range from greater than <NUM> to at most <NUM>.

In accordance with an embodiment, the bond material can include a certain content of boron oxide (B<NUM>O<NUM>) that may facilitate formation of the abrasive article and improve performance. For example, the bond material may include at least <NUM> wt% of boron oxide (B<NUM>O<NUM>), such as at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% for a total weight of the bond material. Still, in at least one non-limiting embodiment, the bond material may include at most <NUM> wt% boron oxide (B<NUM>O<NUM>) for a total weight of the bond material, such as at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for a total weight of the bond material. It will be appreciated that the bond material can include a content of boron oxide within range including any of the minimum and maximum percentages noted above.

According to another embodiment, the bond material may include a certain ratio of a content of alumina relative to the content of boron oxide, such that the bond material includes a ratio (Al<NUM>O<NUM>/B<NUM>O<NUM>) based on weight percent. Such a ratio may facilitate improved formation and/or performance of the abrasive article. In one embodiment, the ratio (Al<NUM>O<NUM>/B<NUM>O<NUM>) can be at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM>. In another embodiment, the ratio (Al<NUM>O<NUM>/B<NUM>O<NUM>) can be at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. Moreover, the ratio (Al<NUM>O<NUM>/B<NUM>O<NUM>) can be in a range including any of the minimum and maximum values noted herein. For instance, the ratio (Al<NUM>O<NUM>/B<NUM>O<NUM>) can be in a range at least <NUM> to at most <NUM>.

In accordance with an embodiment, the bond material can include a certain content of silicon dioxide (SiO<NUM>) that may facilitate formation of the abrasive article and improve performance. For example, the bond material may include at least <NUM> wt% silicon dioxide (SiO<NUM>), such as at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% for a total weight of the bond material. Still, in at least one non-limiting embodiment, the bond material may include at most <NUM> wt% silicon dioxide (SiO<NUM>) for a total weight of the bond material, such as at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for a total weight of the bond material. It will be appreciated that the bond material can include a content of silicon dioxide within range including any of the minimum and maximum percentages noted above.

In still another embodiment, the bond material may include a certain ratio of a content of alumina relative to the content of silicon dioxide, such that the bond material comprises a ratio a ratio (Al<NUM>O<NUM>/SiO<NUM>), based on weight percent. Such a ratio may facilitate improved formation and/or performance of the abrasive article. In one embodiment the ratio (Al<NUM>O<NUM>/SiO<NUM>) can be at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM>. In another embodiment, the ratio (Al<NUM>O<NUM>/SiO<NUM>) can be at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. 61or at most <NUM> or at most <NUM>. Moreover, the ratio (Al<NUM>O<NUM>/SiO<NUM>) can be in a range including any of the minimum and maximum values noted herein. For instance, the ratio (Al<NUM>O<NUM>/SiO<NUM>) can be in a range at least <NUM> to at most <NUM>.

In another embodiment, the bond material may include a certain ratio of a content of boron oxide relative to the content of silicon dioxide, such that the bond material comprises a ratio (B<NUM>O<NUM>/SiO<NUM>), based on weight percent. Such a ratio may facilitate improved formation and/or performance of the abrasive article. In one embodiment the ratio (B<NUM>O<NUM>/SiO<NUM>) can be at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. Still, in one non-limiting embodiment, the ratio (B<NUM>O<NUM>/SiO<NUM>) can be at least at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM> or at least <NUM>. It will be appreciated that the ratio (B<NUM>O<NUM>/SiO<NUM>) can be within range including any of the minimum and maximum values noted above.

According to another aspect, the bond material can include a certain content of sodium oxide (Na<NUM>O), which may facilitate suitable formation and performance of the abrasive article. For example, the bond material can include at least <NUM> wt% sodium oxide (Na<NUM>O) for a total weight of the bond material. In another embodiment, the bond material can include at least <NUM> wt% sodium oxide for a total weigh to of the bond material, such as at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt%. In another non-limiting embodiment, the bond material can include at most <NUM> wt% sodium oxide (Na<NUM>O) for a total weight of the bond material, such as at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for the total weight of the bond material. It will be appreciated that the bond material can include a content of sodium oxide within range including any of the minimum and maximum percentages noted above.

According to another aspect, the bond material can include a particular content of potassium oxide (K<NUM>O), which may facilitate suitable formation and performance of the abrasive article. For example, the bond material can include at least <NUM> wt% potassium oxide (K<NUM>O) for a total weight of the bond material or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt% or at least <NUM> wt%. In another non-limiting embodiment, the bond material can include at most <NUM> wt% potassium oxide (K<NUM>O) for a total weight of the bond material or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% or at most <NUM> wt% for the total weight of the bond material. It will be appreciated that the bond material can include a content of potassium oxide within range including any of the minimum and maximum percentages noted above.

In another embodiment, the bond material can include a content of certain components that facilitates suitable formation and/or performance of the abrasive article. Such components can include manganese dioxide (MnO<NUM>), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe<NUM>O<NUM>), titanium dioxide (TiO<NUM>), barium oxide (BaO), zinc oxide (ZnO), phosphorous oxide (P<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), or any combination thereof. For example, in one instance, the bond material can include at most <NUM> wt% for the total weight of the bond of any one of manganese dioxide (MnO<NUM>), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe<NUM>O<NUM>), titanium dioxide (TiO<NUM>), barium oxide (BaO), phosphorous oxide (P<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), or zinc oxide (ZnO). In another embodiment, the bond material can include at most <NUM> wt% or even not greater than <NUM> wt% of manganese dioxide (MnO<NUM>), magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe<NUM>O<NUM>), phosphorous oxide (P<NUM>O<NUM>), barium oxide (BaO), zinc oxide (ZnO), zirconium oxide (ZrO<NUM>), or titanium dioxide (TiO<NUM>). In one embodiment, the bond material can be essentially free of any one of or combination of manganese dioxide (MnO<NUM>), magnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), zinc oxide (ZnO), iron oxide (Fe<NUM>O<NUM>), phosphorous oxide (P<NUM>O<NUM>), zirconium oxide (ZrO<NUM>), or titanium dioxide (TiO<NUM>).

In accordance with another embodiment, the bonded abrasive body may have a certain content of porosity and type of porosity that may facilitate improved performance of the abrasive article. In accordance with an embodiment the body can include at least <NUM> vol% porosity for a total volume of the body. In a more particular embodiment, the body can include at least <NUM> vol% porosity for the total volume of the body, such as at least <NUM> vol% or at least or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% for a total volume of the body. Still, in other non-limiting embodiment, the body may include a porosity of at most <NUM> vol% for the total volume of the body or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% for a total volume of the body. It will be appreciated that the body can include a content of porosity within a range including any of the minimum and maximum percentages noted above.

The bonded abrasive body of the embodiments herein may have a particular porosity that can facilitate improved performance of the abrasive article. For example, the body may include porosity, wherein at least <NUM>% of the total porosity of the body can be interconnected porosity. Interconnected porosity defines a series of interconnected channels extending through the body. Interconnected porosity may also be referred to herein as open porosity. Open porosity or interconnected porosity can be distinct from closed porosity, which is defined as discrete pores within the body that are not connected to adjacent pores and do not form an interconnected network of channels through the body. Closed porosity does not allow a fluid to flow freely through the volume of the body. In another instance, the body can include at least <NUM>%, such as at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, or even at least <NUM>% interconnected porosity for the total volume or porosity in the body. In at least one embodiment, essentially all the porosity of the body can be interconnected porosity. Still, in at least one non-limiting embodiment, the body can have at most <NUM>%, such as at most <NUM>%, or even at most <NUM>% of the total porosity may be interconnected porosity. It will be appreciated that the body can include a content of interconnected porosity within a range including any of the minimum and maximum values noted above.

In still another instance, the body may include a certain content of abrasive particles, which may facilitate improved performance of the abrasive article. For example, the body may include at least <NUM> vol% abrasive particles for a total volume of the body, such as at least <NUM> vol% or at least <NUM> vol% or at least or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% or at least <NUM> vol% for a total volume of the body for a total volume of the body. Still, in one non-limiting embodiment, the content of abrasive particles in the body can be at most <NUM> vol% for a total volume of the body, such as at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% or at most <NUM> vol% for a total volume of the body. It will be appreciated that the content of the abrasive particles within the body can be within range including any of the minimum and maximum percentages noted above.

In an embodiment, the bonded abrasive body can have a certain modulus of rupture (MOR), such as at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa or at least <NUM> MPa. In another embodiment, the MOR can be at most <NUM> MPa, such as at most <NUM> MPa, at most <NUM> MPa, at most <NUM> MPa, at most <NUM> MPa, or at most <NUM> MPa. The MOR of the body may be affected by the content of the bond material. For instance, the body can have a relatively higher MOR when the body includes a relatively higher content of the bond material. It will be appreciated that the MOR can be in a range including any of the minimum and maximum values disclosed herein. MOR can be measured using a standard <NUM>-point bending test on a sample of size <NUM>"x1"x0. <NUM>", where the load is applied across the <NUM>"x0. <NUM>" plane, generally in accordance with ASTM D790, with the exception of the sample size. The failure load can be recorded and calculated back to MOR using standard equations.

In an embodiment, the bonded abrasive body can have a certain modulus of elasticity (MOE), such as at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa or at least <NUM> GPa. In another embodiment, the MOE can be at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa or at most <NUM> GPa. The MOE of the body may be affected by the content of the bond material. For instance, the body can have a relatively higher MOE when the body includes a relatively higher content of the bond material. It will be appreciated that the MOE can be in a range including any of the minimum and maximum values given above. MOE can be calculated through measurement of natural frequency of the composites using a GrindoSonic instrument or similar equipment, as per standard practices in the abrasive grinding wheel industry. In another embodiment, the bonded abrasive body can have a certain MOE, which can correspond to a certain MOR. For example, the bonded abrasive body can have an MOE of at most <NUM> GPa for a MOR of at least <NUM> MPa. In another instance, the bonded abrasive body can have an MOE of at most <NUM> GPa for a MOR of at least <NUM> MPa.

In one embodiment, the bonded abrasive body can have a ratio of the MOR to MOE. In particular instances, the ratio (MOR/MOE) can be at least <NUM>, such as at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>. Still, the ratio (MOR/MOE) may be at most <NUM>, such as at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, at most <NUM>, or at most <NUM>. It will be appreciated that the ratio (MOR/MOE) of the bonded abrasive bodies can be within a range between any of the minimum and maximum values noted herein.

Notably, the abrasive articles can be suitable for various applications. In accordance with an embodiment, the abrasive article can have a versatility factor as measured according to the versatility test disclosed herein. As used herein, the versatility factor is intended to refer to capability of an abrasive article to perform well in various grinding conditions as outlined in the description of the versatility test. The versatility test is performed as follows.

Workpieces made of tool steel, chrome steel, and carbon steel, respectively, are used for the test. A Heald grinder spindle is used with spindle power set at <NUM> Hp. TRIM® VHP® E812 is used as the coolant. The wheel speed of <NUM> SFPM used. The abrasive article is tested on all the workpieces at the material removal rate Q'w of <NUM> and <NUM> in<NUM>/in/min. Each workpiece is ground for <NUM> to <NUM> passes at each removal rate Q'w, and power draw is recorded for each pass. As used herein, Q'w is determined by the equation of Q'W=(VW X ae), wherein VW is feed-rate in in/min, and ae is depth of cut per pass in cm (inch).

The maximum power draw difference between the workpieces for each grind number is added up, the total of which is divided by <NUM> to obtain the average maximum difference for each removal rate. The versatility factor is the reciprocal of the bigger of the average maximum power draw differences of the two removal rates. The higher the versatility factor, the more versatile the abrasive article.

<FIG> includes an illustration of a plot of power draw versus grinding conditions of a representative grinding wheel tested according to the versatility test. The workpieces were made of tool steel (WP1), carbon steel (WP2), and chrome steel (WP3), respectively. As illustrated, power draw varies when testing conditions change. At the removal rate of <NUM> in<NUM>/in/min, wherein <NUM> inch = <NUM>, the maximum difference at grind number <NUM> (pass <NUM>) is between WP3 and WP1, while the maximum difference at grind number <NUM> is between WP2 and WP1. All the maximum differences are added and divided by <NUM> to obtain the average maximum power draw difference for the removal rate of <NUM> in<NUM>/in/min and <NUM> in<NUM>/in/min, respectively, wherein <NUM> inch = <NUM>. As disclosed later in this application, the maximum power draw difference for the rate of <NUM> in<NUM>/in/min is <NUM>, and for <NUM> in<NUM>/in/min <NUM>. The versatility factor of the grinding wheel is <NUM>/<NUM>, which equals <NUM>. As used herein, power draw is the average power draw for each tested grind number.

In accordance with an embodiment, the abrasive article can have a versatility factor of at least <NUM>, or at least <NUM>, or at least <NUM>, or at least <NUM>. In another embodiment, the abrasive article can have a versatility factor of at most <NUM>, such as at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM> or at most <NUM>. Moreover, the versatility factor can be within a range including any of the minimum and maximum values disclosed herein.

Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention.

Representative (S1) and conventional (C1) grinding wheels were formed having the bond compositions included in Table <NUM> and <NUM>, respectively. Contents of BaO, MnO<NUM>, ZrO<NUM>, and ZnO were expected to be low and not tested, but it should be understood the sum of all the components totals <NUM>%. The contents of the components are relative to the total weight of the bond material.

The mixtures including the bond precursor material and white alumina abrasive particles were casted into a mold having dimensions of <NUM> x <NUM> x <NUM> ( <NUM> inches x <NUM> inches x <NUM> inches) to form green bodies of samples S1 and C1. The green bodies were kept in the molds and heat treated at approximately <NUM> for <NUM> hours in air to form finally-formed abrasive bodies.

Each of samples S1 and C1 included <NUM> vol% of the bond materials, <NUM>. 74vol% of porosity, and <NUM> vol% of nanocrystalline alumina abrasive particles with respect to the total volume of the body of the wheel.

<FIG> includes images of cross sections of the bodies of C1 and S1 under the magnification of 30X. As demonstrated, bond bridges are black. Abrasive particles and pores are not visible. At least <NUM> cross-sectional SEM images of were analyzed using ImageJ as described in embodiments of this disclosure. As noted in Table <NUM> below and <FIG>, S1 had significantly more bond bridges in average than C1, and thus, an improved microstructure over C1.

<FIG> includes a graph illustrating the distribution of bond bridges of S1 vs. C1. As illustrated, wheels S1 had higher number of smaller bridges compared to C1.

Additional representative (S2) and conventional (C2) grinding wheels were formed in the same manner as described in Example <NUM> and having the same bond compositions as S1 and C1, respectively, and the same abrasive particles. Each of the wheels S2 and C2 included <NUM> vol% of the bond materials, <NUM> vol% of porosity, and <NUM> vol% of nanocrystalline alumina abrasive particles for the total volume of the body of the wheel.

<FIG> includes high-contrasting SEM images of cross sections of the bodies of C2 and S2 wheels. As demonstrated, bond bridges are black, and abrasive particles and pores are not visible, as they are white. The number of the bond bridges was determined in the same manner as described in Example <NUM> except images of <NUM> cross sections were analyzed for the average number of bond bridges. As disclosed in Table <NUM> below and <FIG>, S2 had significantly higher number of bond bridges than C2, indicating S2 had an improved microstructure over C2.

<FIG> includes an illustration of the bond bridge distribution of S2 vs. C2. As illustrated, wheels S2 had higher number of smaller bridges compared to C2.

Representative (S3) and conventional (C3 to C8) grinding wheel were formed in the same manner as disclosed in Example <NUM> and having the compositions included in Table <NUM> below and white alumina abrasive particles. The contents of the components are in weight percent and relative to the total weight of the bond material.

Each of the wheel samples included for the total volume of the body of the wheel, <NUM> vol% of the bond materials, <NUM> vol% of porosity, and <NUM> vol% of abrasive particles. OD grinding was tested on wheels S3 and C3 to C8 to determine the versatility of the samples in accordance with embodiments described herein.

<FIG> includes plot of power draw vs. the number of cuts for each removal rate of the tested samples. Wheels C3 to C8 demonstrated bigger spread of power draw between different workpieces and over the entire range of the cut numbers as compared to S3. The average maximum powder draw difference for each removal rate Q'w and versatility factors of the wheels are included in Table <NUM> below.

Additional representative (S9) and conventional (C9) grinding wheels were formed in the same manner as described in Example <NUM> and having the same bond compositions as S1 and C1, respectively, and the same abrasive particles. Each of the wheels S9 and C9 included <NUM> vol% to <NUM> vol% of the bond materials, <NUM> vol% to <NUM> vol% of porosity, and <NUM> vol% of nanocrystalline alumina abrasive particles for the total volume of the body of the wheel. It is to be understood that the total of the contents of bond material, porosity, and abrasive particles makes up <NUM>%, even though a range for bond and porosity is provided.

<FIG> includes high-contrasting SEM images of cross sections of the bodies of C9 and S9 wheels. As demonstrated, bond bridges are black, and abrasive particles and pores are not visible. The number of the bond bridges was determined in the same manner as described in Example <NUM> except <NUM> cross-sectional images were analyzed for the average number of bond bridges. As disclosed in <FIG>, S9 had significantly higher number of bond bridges than C9, indicating S9 had an improved microstructure over C9.

<FIG> includes a graph illustrating the distribution of bond bridges of S9 vs. C9. As illustrated, wheels S9 had higher number of smaller bridges compared to C9.

Additional representative (S10) and conventional (C10) grinding wheels were formed in the same manner as described in Example <NUM> and having the same bond compositions as S1 and C1, respectively, and the same abrasive particles. Each of the wheels S10 and C10 included <NUM> vol% of the bond materials, <NUM> vol% of porosity, and <NUM> vol% of nanocrystalline alumina abrasive particles for the total volume of the body of the wheel.

<FIG> includes SEM images of cross sections of the bodies of C10 and S10 wheels. As demonstrated, bond bridges are black, and abrasive particles and pores are not visible. The number of the bond bridges was determined in the same manner as described in Example <NUM> except <NUM> cross-sectional images were analyzed for the average number of bond bridges. As disclosed in <FIG>, S10 had significantly higher number of bond bridges than C10, indicating S10 had an improved microstructure over C10.

<FIG> includes a graph illustrating the distribution of bond bridges of S10 vs. C10. As illustrated, wheels S10 had higher number of smaller bridges compared to C10.

Up to about <NUM> of the bond materials of samples S1 and C1 were placed on an alumina plate, respectively, and tested using Optical Fleximeter Misura® <NUM> (from Expert System Solutions). <FIG> illustrate a microscopic image of the bond materials of S1 and C1 on an alumina plate at room temperature, respectively. The bond materials S1 and C1 were heated at about <NUM> for <NUM> to <NUM> minutes, and the microscopic images of the heated bond materials S1 and C1 are illustrated in <FIG>, respectively. The angles formed by the heated bond material with respect to the contacting surface of the alumina plate were recorded and analyzed following the instructions provided with Optical Fleximeter Misura® <NUM>. As demonstrated in <FIG>, the angles formed between S1 and the contacting surface of the alumina plate is from about <NUM>° to about <NUM>°. As demonstrated in <FIG>, the angles formed by C1 with respect to the contacting surface of the alumina plate is from about <NUM>° to about <NUM>°.

Bar samples having the same compositions as samples C1, S1, C9, S9, C10, and S10, respectively, were formed. At least <NUM> bars of each composition were tested for MOR and MOE as described in embodiments of this disclosure. Table <NUM> below includes the test data.

The foregoing embodiments are directed to bonded abrasive products, and particularly grinding wheels, which represent a departure from the state-of-the-art. The abrasive articles of the embodiments herein utilize a combination of features that facilitate improved performance over conventional wheels. As described in the present application, the abrasive articles can include a vitrified bond material having a particular weight content ratio of alumina (Al<NUM>O<NUM>) to lithium oxide (Li<NUM>O), which in combination of the bond composition, allows improved formation and performance in various applications of the abrasive articles. During formation of the abrasive article, the bond material disclosed in embodiments herein demonstrates a higher viscosity and lower flowability, compared to conventional bond materials. As noted in Example <NUM>, the bond material can form a smaller angle with respect to the contacting surface, which can be surfaces of abrasive particles, which allows formation of improved microstructure, such as improved number of bond bridges, bond bridges with smaller areas, and smaller pores. The microstructure, in combination with abrasive particles and filler material, has led to significant and unexpected results in terms of versatility of abrasive articles, allowing the same abrasive articles to perform well in various applications involving different grinding conditions, workpieces, and other parameters that are application-based.

Reference herein to a material including one or more components may be interpreted to include at least one embodiment wherein the material consists essentially of the one or more components identified. The term "consisting essentially" will be interpreted to include a composition including those materials identified and excluding all other materials except in minority contents (e.g., impurity contents), which do not significantly alter the properties of the material. Additionally, or in the alternative, in certain non-limiting embodiments, any of the compositions identified herein may be essentially free of materials that are not expressly disclosed. The embodiments herein include range of contents for certain components within a material, and it will be appreciated that the contents of the components within a given material total <NUM>%.

Claim 1:
An abrasive article comprising:
a body (<NUM>) including:
a bond material (<NUM>) extending throughout the body, wherein the bond material (<NUM>) comprises greater than <NUM> wt% aluminum oxide (Al<NUM>O<NUM>) for a total weight of the bond material (<NUM>) and at least <NUM> wt% and less than <NUM> wt% of lithium oxide for a total weight of the bond material (<NUM>); and
abrasive particles (<NUM>) contained within the bond material (<NUM>); and
porosity of at most <NUM> vol% and at least <NUM> vol% for a total volume of the body.