Abrasive grits formed of ceramic containing oxides of aluminum and yttrium, method of making and using the same and products made therewith

Ceramic abrasive grits comprising alpha alumina and at least about 0.5 percent by weight yttria are prepared by mixing an aqueous dispersion of alpha alumina monohydrate and yttrium compound, gelling the resultant mixture, drying the gel to produce a dried solid, crushing the dried material to produce grits, calcining the dried grits to substantially remove bound volatile materials, and firing the grits to produce a ceramic material. The yttrium for the most part is in the form of a yttrium aluminum garnet. Abrasive products comprising the abrasive grits are also claimed as is a method of grinding a workpiece with such abrasive products.

DESCRIPTION 
1. Technical Field 
This invention relates to the production of alumina-based ceramic abrasive 
grits, a method of making the same by a sol-gel process, abrasive products 
made with the abrasive grits and a method of using the abrasive products. 
2. Background Art 
Garnet is known to be an important naturally-occurring abrasive mineral, 
grits of which find use in large part in coated abrasive products. The 
garnet extensively used for abrasive purposes consists almost wholly of 
var.almandite, Fe.sub.3 Al.sub.2 (SiO.sub.4).sub.3, with small amounts of 
pyrope, Mg.sub.3 Al.sub.2 (SiO.sub.4).sub.3, in a solid solution. The term 
"garnet" has, in recent years, been broadened to include a class of 
non-siliceous mixed oxides composed of compounds of certain rare earth 
(e.g., Y, Gd) oxides with oxides of Fe or Al. These compounds have a 
garnet structure and have considerable interest in the electronic field 
but have not been considered as abrasives as recognized on pages 34-37, L. 
Coes, Jr., Abrasives, Springer-Verlag, 1971. 
While yttria (Y.sub.2 O.sub.3) has been included in a co-fused alumina 
zirconia abrasive, as disclosed in Poon et al, U.S. Pat. No. 4,457,767, 
there has been no disclosure of yttria or of a yttrium aluminum garnet in 
a ceramic abrasive material, particularly one made by a sol-gel process. 
The preparation by a sol-gel process of dense, alumina-based ceramic 
abrasive grain is described, for example, in Leitheiser et al, U.S. Pat. 
No. 4,314,827, assigned to the assignee of the present application. This 
patent teaches making an abrasive mineral employing chemical ceramic 
technology by gelling alumina monohydrate with a precursor of at least one 
modifying component followed by dehydration and firing. The modifying 
component is selected from zirconia, hafnia, a combination of zirconia and 
hafnia, and a spinel derived from alumina and at least one oxide of 
cobalt, nickel, zinc, or magnesium. Minnesota Mining and Manufacturing 
Company, the assignee of the present application, markets sol-gel alumina 
based ceramic abrasive grits under the trade designation "Cubitron". 
Abrasive products containing "Cubitron" abrasive grits have been found to 
perform in a superior manner as compared to the best fused synthetic 
abrasive mineral in many applications. A typical example of a high 
performance fused synthetic abrasive mineral is formed of fused 
alumina-zirconia available, for example, under the trade designation 
"NorZon" from the Norton Company. 
While sol-gel alumina-based ceramic abrasive mineral outperforms the fused 
alumina-zirconia mineral in many applications, it does not out perform 
fused synthetic alumina zirconia in abrading certain workpieces such as 
those made of stainless steel substrates. 
SUMMARY OF THE INVENTION 
The present invention provides ceramic abrasive grits formed by a sol-gel 
process which have superior abrasive performance in abrading certain 
workpieces such as those made of stainless steel, titanium, high nickel 
alloys, aluminum and others, and excellent performance on more 
conventional workpieces such as mild steel. The ceramic abrasive grits 
comprise alpha alumina and at least about 0.5% (preferably about 1% to 
about 30%) by weight yttria. 
The ceramic abrasive grits are made by a process comprising the steps of: 
a. mixing an aqueous dispersion of alpha alumina monohydrate and yttrium 
compound in an amount to provide at least about 0.5% by weight yttria upon 
firing; 
b. gelling the resultant mixture; 
c. drying the gel to produce a dried solid; 
d. crushing the dried material to produce grits; 
e. calcining the dried grits to substantially remove bound volatile 
materials; and 
f. firing the grits to produce a ceramic material. 
It is believed that substantially all of the yttrium is present as yttrium 
aluminum garnet, although under certain conditions other crystal forms of 
yttrium aluminum oxide may exist or be present with the garnet. The 
yttrium content is reported as weight percent of yttria (Y.sub.2 O.sub.3) 
for convenience even though it does not necessarily exist as such in the 
ceramic because it usually is in the garnet form.

DETAILED DESCRIPTION 
The preparation of the ceramic abrasive grits of the present invention from 
a sol-gel process includes the preparation of a dispersion usually 
comprising about 2 to about 60 weight percent alpha aluminum oxide 
monohydrate (boehmite). The boehmite can either be prepared from various 
techniques well known in the art or can be acquired commercially from a 
number of suppliers. Examples of commercially available materials include 
that available under the trade designation "Disperal" produced by Condea 
Chemie, GMBH and that available under the trade designation "Catapal" 
S.B., produced by Vista Chemical Company. These aluminum oxide 
monohydrates are in the alpha-form, are relatively pure, include 
relatively little, if any, hydrate phases other than the monohydrate, and 
have a high surface area. 
A peptizing agent is usually added to the boehmite dispersion to produce a 
more stable hydrosol or colloidal dispersion. Monoprotic acids or acid 
compounds which may be used as the peptizing agent include hydrochloric, 
acetic, and nitric acid. Nitric acid is a preferred peptizing agent. 
Multiprotic acids are normally avoided since they rapidly gel the 
dispersion, making it difficult to handle or mix with additional 
components. Some commercial sources of boehmite certain acid titer, such 
as absorbed formic or nitric acid, to assist in forming a stable 
dispersion. 
Sufficient yttrium compound is added to the dispersion to provide at least 
about 0.5% by weight and preferably about 1 to 30% by weight yttria after 
firing. The preferred yttrium compound is a salt of a volatile anion. 
Yttrium salts having volatile anions include, for example, yttrium 
nitrate, yttrium formate, yttrium acetate and the like. The most readily 
available yttrium compound is yttrium oxide which is easily converted to a 
yttrium salt with a volatile anion by reaction with an excess of 
concentrated nitric acid to produce yttrium nitrate hexahydrate solution 
which can conveniently be introduced into the alpha aluminum oxide 
monohydrate dispersion in the desired amount. Yttrium salts and compounds 
which remain stable and have anions which do not volatilize at least at 
the firing temperature of the ceramic material should be avoided since 
they generally do not react with alumina to form the yttrium-aluminum 
garnet. The yttrium compound may also be yttria, for example, as finely 
divided hydrated particles as in a sol. 
The alpha aluminum oxide monohydrate may be formed by any suitable means 
which may simply be the mixing of the aluminum oxide monohydrate with 
water containing the peptizing agent or by forming an aluminum oxide 
monohydrate slurry to which the peptizing agent is added. Once the 
dispersion is formed, it is preferably then gelled. The gel can be formed 
by any conventional technique but is preferably formed by adding the 
yttrium salt in sufficient concentration as to cause the dispersion to 
gel. 
The dispersion may contain a nucleating agent to enhance the transformation 
to alpha alumina. Suitable nucleating agents include fine particles of 
alpha alumina, alpha ferric oxide or its percursor and any other material 
which will nucleate the transformation. The amount of nucleating agent is 
sufficient to effect nucleation. Nucleating such dispersions is disclosed 
in assignee's copending application Ser. No. 728,852 filed Apr. 30, 1985, 
the disclosure of which is incorporated herein by reference. 
The dispersion may contain one or more precursors of one or more other 
modifying additives which can be added to enhance some desirable property 
of the finished product or increase the effectiveness of the sintering 
step. These additives may also be in the form of soluble salts, typically 
water soluble, and typically consist of a metal-containing compound which 
can be a precursor of the oxides of magnesium, zinc, cobalt, nickel, 
zirconium, hafnium, chromium and titanium. The addition of 
metal-containing compounds, such as those containing magnesium, zinc, 
cobalt and nickel, which form a spinel crystal structure, has generally 
been found to produce better abrasive grits than ceramics which do not 
contain spinel at the same yttria concentration, for example, at a yttria 
content of about 10% by weight. 
Once the gel has formed, it may be shaped by any convenient method such as 
pressing, molding or extrusion and then carefully dried to produce the 
desired shape such as a rod, pyramid, diamond, cone and the like. 
Irregularly shaped abrasive grits are conveniently formed by simply 
depositing the gel in any convenient size of drying vessel such as one in 
the shape of a cake pan and drying the gel, usually at a temperature below 
the frothing temperature of the gel. Drying may be accomplished by simply 
air drying or using any of several other dewatering methods that are known 
in the art to remove the free water of the gel to form a solid. 
After the solid is dried, it can be crushed or broken by any suitable 
means, such as a hammer or ball mill to form grits or particles. Any 
method for comminuting the solid can be used and the term "crushing" is 
used to include all of such methods. 
After crushing, the dried gel can then be calcined to remove essentially 
all volatiles. The dry gel is generally heated to a temperature between 
400.degree. C. and about 800.degree. C. and held within this temperature 
range until the free water and a substantial amount of the bound water is 
removed, preferably over 90 weight percent of the total water. 
The calcined material is then sintered by heating to a temperature between 
about 1200.degree. C. to about 1650.degree. C. and holding within this 
temperature range until substantially all of the yttrium reacts with 
alumina to thereby be converted to yttrium-aluminum garnet and until 
substantially all of the remaining alumina is converted to alpha alumina. 
Of course, the length of time to which the calcined material must be 
exposed to the sintering temperature to achieve this level of conversion 
will depend upon various factors but usually from about 2 to about 30 
minutes is sufficient. 
Other steps can be included in this process, such as rapidly heating the 
material from the calcining temperature to the sintering temperature, 
sizing granular material, centrifuging the dispersion to remove sludge 
waste, etc. Moreover, this process may be modified by combining two or 
more of the individually described steps, if desired. 
The conventional process steps and materials are more fully described in 
U.S. Pat. No. 4,314,827 and U.S. Pat. No. 4,518,397, these patents being 
herein incorporated by reference. 
The ceramic materials according to the invention may have a density varying 
from near its theoretical density, e.g., 95% or greater, to about 75%. The 
ceramic material may be substantially void free or it may be characterized 
by including porosity, typically in the form of internal vermicular or 
equiaxial pores which are for the most part on the interior of the ceramic 
with a minor part of the pores extending to the surface. Porosity is very 
difficult to measure accurately by conventional porosity measuring 
techniques because the porosity is a mix of closed pores which do not 
extend to the surface and open pores which do. 
The ceramic abrasive grits according to the present invention may be 
utilized in conventional abrasive products, preferably as a blend with 
less expensive conventional abrasive grits such as fused alumina, silicon 
carbide, garnet, fused alumina-zirconia and the like. It may also be 
blended with minerals or materials which are not noted as abrasives such 
as marble, glass, and the like. 
Because of the relatively high cost of yttrium compounds, it is preferred 
to blend the ceramic abrasive grits of the present invention with less 
expensive abrasive minerals. Such blending of abrasive grits is known. A 
preferred method of blending is described in assignee's U.S. patent 
application Ser. No. 721,869 filed Apr. 10, 1985, involving a method known 
as selective mineral substitution wherein the coarse abrasive mineral is 
removed from an inexpensive abrasive grit charge that is to be utilized in 
an abrasive product such as a coated abrasive and is substituted with 
coarse mineral of the invention. It is recognized in that patent 
application that in any coated abrasive the coarse abrasive grits are 
substantially responsible for a major portion of the abrading of a 
workpiece. By such substitution, the improved abrasive grits of the 
present invention are interposed in an abrasive product between smaller 
grits of conventional abrasive mineral to permit the improved coarse 
abrasive grits to do the bulk of the abrading with such product. 
Aforementioned U.S. patent application Ser. No. 721,869 is incorporated 
herein by reference for its disclosure of this feature. 
The ceramic abrasive grits of the present invention are conveniently 
handled and incorporated into various abrasive products according to 
well-known techniques to make, for example, coated abrasive products, 
bonded abrasive products, and lofty non-woven abrasive products. The 
method of making such abrasive products are well-known to those skilled in 
the art. A coated abrasive product includes a backing, for example, formed 
of fabric (e.g., woven or non-woven fabric such as paper) which may be 
impregnated with a filled binder material, a polymer film such as that 
formed of oriented heat-set polypropylene or polyethylene terephthalate 
which may be first primed, if needed, with a priming material, or any 
other conventional backing material. The coated abrasive also includes a 
binder material, typically in layers including a make or maker coat, a 
size or sizing coat and possibly a supersize coat. Conventional binder 
materials include phenolic resins. 
It has been found that the addition of a grinding aid over the surface of 
the abrasive grits typically in the supersize coating provides an 
unexpectedly improved grinding performance when using a coated abrasive 
product containing the ceramic abrasive grits of the present invention. 
Grinding aids may also be added to the size coat or as particulate 
material. The preferred grinding aid is KBF.sub.4, although other grinding 
aids are also believed to be useful. Other useful grinding aids include 
NaCl, sulfur, K.sub.2 TiF.sub.6, polyvinylidene chloride, cryolite and 
combinations and mixtures thereof. The preferred amount of grinding aid is 
on the order of 50 to 300 g., preferably 80 to 160 g, per square meter of 
coated abrasive product. 
Non-woven abrasive products typically include an open porous lofty polymer 
filament structure having the ceramic abrasive grits distributed 
throughout the structure and adherently bonded therein by an adhesive 
material. The method of making such non-woven abrasive products is well 
known. 
Bonded abrasive products typically consist of a shaped mass of abrasive 
grits held together by an organic or ceramic binder material. The shaped 
mass is preferably in the form of a grinding wheel. The preferred binder 
materials for the ceramic abrasive grits of the invention are organic 
binders. Ceramic or vitrified binders may be used if they are curable at 
temperatures and under conditions which will not adversely affect the 
ceramic abrasive grits of the present invention. 
EXAMPLES 
The following examples are illustrative of certain specific embodiments of 
this invention; however, these examples are for illustrative purposes only 
and are not to be construed as limitations upon the invention. All parts 
are by weight, unless otherwise specified. 
Examples 1-85 
Alpha alumina/yttrium-aluminum garnet abrasive grits were prepared by sol 
gel process as follows: 
Room temperature deionized water (2600 ml), 48 g of 16N analytical reagent 
grade nitric acid and 800 g alpha aluminum monohydrate powder sold under 
the trade designation "Disperal" were charged into an 18.9 liter 
polyethylene lined steel vessel. The charge was dispersed at high speed 
for five minutes using a Gifford-Wood Homogenizer Mixer (Greeco Corp., 
Hudson, N.H.). The resulting dispersion and an aqueous solution containing 
35.9% yttrium nitrate hexahydrate were metered through an in-line mixer in 
an amount to provide the weight of yttrium nitrate solution specified in 
Table I. The resulting gel was extruded into a 46 cm.times.66 cm.times.5 
cm polyester lined aluminum tray where it was dried in a forced air oven 
at 100.degree. C. to a friable solid. The resultant dried material was 
crushed using a "Braun" type UD pulverizer having a 1.1 mm gap between the 
steel plates. The crushed material was screened and the 0.125 mm to about 
1 mm screen size material was retained for firing. 
The screened, crushed material was fed into the end of a calciner which was 
a 23 cm diameter 4.3 meter long stainless steel tube having a 2.9 meter 
hot zone, the tube being inclined at 2.4 degrees with respect to the 
horizontal, and rotating at 7 rpm, to provide residence time therein of 
about 15 minutes. The calciner had a hot zone feed end temperature of 
350.degree. C. and exit end temperature of 800.degree. C. The fired 
product from calciner was fed into a 1380.degree. C. kiln which was a 8.9 
cm diameter 1.32 meter long silicon carbide tube inclined at 4.4 degrees 
with respect to the horizontal and having a 76 cm hot zone, rotating at 
10.5 rpm, to provide a residence time therein of about 5 minutes. The 
product exited the kiln into room temperature air where it was collected 
in a metal container and allowed to cool to room temperature. 
Precursors of other modifies were added to examples 63-72 and 80-84 in the 
type and in the amounts specified in Table I. 
TABLE I 
______________________________________ 
Y(NO.sub.3).sub.3.6H.sub.2 O 
Example 
solution Other Additive Precursor 
No. (g) (Type) (g) 
______________________________________ 
1 88 
2 166 
3 265 
4 353 
5 465 
6 585 
7 505 
8 606 
9 714 
10 819 
11 959 
12 585 
13 585 
14 585 
15 585 
16 585 
17 585 
18 585 
19 585 
20 504 
21 504 
22 504 
23 504 
24 504 
25 504 
26 504 
27 504 
28 504 
29 504 
30 504 
31 504 
32 504 
33 504 
34 504 
35 504 
36 504 
37 504 
38 504 
39 504 
40 606 
41 504 
42 408 
43 357 
44 504 
45 408 
46 317 
47 231 
48 504 
49 408 
50 324 
51 231 
52 182 
53 150 
54 119 
55 89 
56 58 
57 28 
58 504 
59 408 
60 325 
61 232 
62 317 
63 254 Mg(NO.sub.3).sub.2.6H.sub.2 O 
110.sup.1 
64 182 Mg(NO.sub.3).sub.2.6H.sub.2 O 
223.sup.1 
65 119 Mg(NO.sub. 3).sub.2.6H.sub.2 O 
338.sup.1 
66 58 Mg(NO.sub.3).sub.2.6H.sub.2 O 
455.sup.1 
67 357 Alpha-Al.sub.2 O.sub.3 
150.sup.2 
68 254 Co(NO.sub.3).sub.2.6H.sub.2 O 
120.sup.3 
69 254 Zn(NO.sub.3).sub.2.6H.sub.2 O 
120.sup.4 
70 254 Ni(NO.sub.3).sub.2.6H.sub.2 O 
120.sup.5 
71 254 Mg(NO.sub.3).sub.2.6H.sub.2 O 
120.sup.1 
72 264 ZrO(NO.sub.3).sub.2.6H.sub.2 O 
194.sup.6 
73 317 
74 44 
75 36 
76 29 
77 22 
78 14 
79 7 
80 59 Mg(NO.sub.3).sub.2.6H.sub.2 O 
112.sup.1 
81 61 Mg(NO.sub.3).sub.2.6H.sub.2 O 
464.sup.1 
82 154 Mg(NO.sub.3).sub.2.6H.sub.2 O 
295.sup.1 
83 251 Mg(NO.sub.3).sub.2.6H.sub.2 O 
120.sup.1 
84 260 Mg(NO.sub.3).sub.2.6H.sub.2 O 
496.sup.1 
85 504 
______________________________________ 
Footnotes 
.sup.1 5.5% MgO solids. 
.sup.2 nucleating agent (1:1 by weight aqueous dispersion). 
.sup.3 5.5% CoO solids solution. 
.sup.4 5.5% ZnO solids solution. 
.sup.5 5.5% NiO solids solution. 
.sup.6 20% ZrO.sub.2 solids solution. 
Table II shows the composition of the abrasive grits made in accordance 
with Examples 1-85. Table III reports the composition, based upon the 
weight of starting materials, as weight percent of aluminum oxide and 
weight percent of yttrium oxide. 
The actual composition of the mineral, for example of the type described in 
Example 20, as observed by optical, scanning electron and transmission 
electron microscopic analysis reveals a rather well defined 
microstructure. 
Optical microscopy reveals no sharp birefringence, indicating an alpha 
alumina crystal domain size of less than about 4 micrometers since alpha 
alumina is the only optically active phase which would reveal strong color 
birefringence and only when the crystal domain size is greater than 4 
micrometers. 
Scanning electron microscopy analysis was conducted on a coated polished 
sample of the type described in Example 20 with a light Au-Pd deposit on 
the polished surface using both secondary electron and background or back 
scatter electron imaging to determine the microcrystal and macrocrystal 
structure. The macrocrystal structure, best detected using back scatter 
electron imaging, revealed 1 to 2 micro diameter crystal domains 
containing darker inclusions and being surrounded by a Y.sub.2 O.sub.3 - 
rich bright ring or zone. The darker inclusions had a higher alpha alumina 
content and lower yttrium-aluminum garnet (3Y.sub.2 O.sub.3 -5Al.sub.2 
O.sub.3) content. The bright rings (zones) were rich in yttrium oxide and 
composed of yttrium-aluminum garnet and alpha alumina. 
Transmission electron microscopy revealed 1 to 1.5 micrometer diameter 
alpha alumina crystal domains, each of which contained a plurality of 
200-600 .ANG. yttrium aluminum garnet inclusions, with a ring composed of 
alpha alumina and yttrium aluminum garnet surrounding the alpha alumina 
crystal domains. 
Abrasive grits of each of the examples were made into coated abrasive 
products which were tested for abrasiveness. The coated abrasive products 
were made according to conventional coated abrasive making procedures. The 
abrasive grits were screened to yield various grain sizes or abrasive grit 
grades and the desired grade selected for the particular construction. The 
abrasive grits were bonded to polyester or vulcanized fiber backings using 
conventional make, size, and optionally supersize adhesive resin 
compositions. 
Table II reveals the grit size (grade), the composition of the make resin, 
size resin, supersize resin, if used, and grinding aid, if used. The 
percent of mineral according to the invention (identified as "YAG") is 
also reported with the balance of 100% being fused alumina. Table II also 
reports the particular grinding test, grinding pressure, type of workpiece 
and grinding duration utilized in the grinding test for each of Examples 
1-85. In Table II, the given grade size refers to abrasive grit having an 
average diameter as follows: 
______________________________________ 
Average 
Diameter 
Grade (micrometers) 
______________________________________ 
36 650 
50 430 
60 340 
80 240 
______________________________________ 
The terms "belt" test and "disc" test refer to belt and disc tests 
hereinafter described. 
The disc test involved the testing of 17.8 cm diameter abrasive discs 
having the following approximate coating weights: 
______________________________________ 
Grade Make Resin Mineral Size Resin 
Supersize 
______________________________________ 
36 4.2 g 18.8 g 13.6 g 8 g 
50 4.2 g 13.2 g 8.7 g 6 g 
______________________________________ 
The abrasive belts were made of 6.35 cm.times.335 cm butt spliced strips. 
The approximate coating weights of the abrasive belts were as follows: 
______________________________________ 
Grade Make Resin Mineral Size Resin 
Supersize 
______________________________________ 
36 70 218 91 35 
50 57 146 68 26 
60 51 121 58 22 
80 43 90 47 18 
______________________________________ 
Disc Test 
The discs were prepared using conventional coated abrasive making 
procedures, conventional 0.76 mm vulcanized fiber backings and 
conventional calcium carbonate-filled phenolic resin make and size resins, 
without adjusting for mineral density differences. The make resin was 
precured for 90 minutes at 88.degree. C. and the size resin precured for 
90 minutes at 88.degree. C. followed by a final cure of 100.degree. C. for 
10 hours. The coating was done using conventional techniques in a one-trip 
operation with curing in a forced air oven. The cured discs were first 
conventionally flexed to controllably break the hard bonding resins, 
mounted on a beveled aluminum back-up pad, and used to grind the face of a 
2.5 cm by 18 cm steel workpiece. The identity of the workpiece is set 
forth in Table II. The workpiece identified as "304SS" refers to 304 
Stainless Steel while "1018MS" refers to 1018 Mild Steel. The disc was 
driven at 5,500 rpm while the portion of the disc overlaying the beveled 
edge of the back-up pad contacted the workpiece at the pressure designated 
in Table II, generating a disc wear path of about 140 cm.sup.2. Each disc 
was used to grind a separate workpiece for one minute each for the time 
designated as grinding duration. The total cut for each disc is reported 
in Table III. The relative cumulative cut of each of the 12 cuts for each 
disc, using the cumulative cut of a disc made of a control adhesive grain 
as 100%, was calculated and is also tabulated in Table III. In Table III 
"Cubitron" refers to the ceramic abrasive grain sold under the trade 
designation "Cubitron". "Norzon" refers to the fused alumina-zirconia 
abrasive grain used under the trade designation "Norzon". 
Belt Test 
The abrasive grain samples which were used to make coated abrasives which 
were converted to endless abrasive belts were tested on a constant load 
surface grinder by abrading the 2.5.times.18 cm face of a steel workpiece 
of the type designated in Table II with successive 60 second grinding 
passes, weighing and cooling after each pass, employing the pressure and 
workpiece set forth in Table II. The workpiece was oriented with its long 
dimension vertical and, during abrading, was moved vertically in a 18.4 cm 
path in a cycle from its original position and back again for the duration 
in minutes shown in Table II. Grinding results are shown in Table III both 
as "total cut" and as a relative amount ("relative cut") when compared to 
control abrasive belts made in the same manner of the designated known 
abrasive grain. 
In Table II, resin "A" consisted of 52 weight percent calcium carbonate and 
48 weight percent phenol-formaldehyde phenolic resin. Resin "B" consisted 
of 68 weight percent calcium carbonate and 32 weight percent 
phenol-formaldehyde resin. Resin "C" consisted of 76.25 weight percent 
KBF.sub.4 dispersed in amine curable epoxy resin and sufficient amine 
curing agent to cure the resin. Resin "D" contained 68 weight percent 
KBF.sub.4 and 32 weight percent phenol-formaldehyde resin with sufficient 
wetting agent to suspend the KBF.sub.4. The resin compositions were 
typically coated from a solvent solution. Resin "E" consisted of 66 weight 
percent cryolite, 32 weight percent phenol-formaldehyde phenolic resin and 
2 weight percent iron oxide. 
TABLE II 
__________________________________________________________________________ 
Super Grinding Grinding 
Ex. Make 
Size 
Size 
Grinding 
Mineral 
Grinding 
Pressure Duration 
No. 
Grade 
Resin 
Resin 
Resin 
Aid % YAG 
Test (kg/cm.sup.2) 
Workpiece 
(min) 
__________________________________________________________________________ 
1 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
2 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
3 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
4 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
5 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
6 50 A B NONE 
NONE 100 DISC 1.41 304SS 12 
7 36 A D NONE 
KBF.sub.4 
100 DISC 0.92 304SS 12 
8 36 A D NONE 
KBF.sub.4 
100 DISC 0.92 304SS 12 
9 36 A D NONE 
KBF.sub.4 
100 DISC 0.92 304SS 12 
10 36 A C NONE 
KBF.sub.4 
100 DISC 0.92 304SS 12 
11 36 A C NONE 
KBF.sub.4 
100 DISC 0.92 304SS 12 
12 36 A B C KBF.sub.4 
100 BELT 2.11 304SS 30 
13 36 A B C KBF.sub.4 
17 BELT 2.11 304SS 30 
14 50 A B C KBF.sub.4 
100 BELT 1.76 304SS 30 
15 50 A B C KBF.sub.4 
10 BELT 1.76 304SS 30 
16 80 A B C KBF.sub.4 
100 BELT 1.06 304SS 30 
17 80 A B C KBF.sub.4 
11 BELT 1.06 304SS 30 
18 50 A D NONE 
KBF.sub.4 
100 DISC 1.06 304SS 12 
19 50 A D NONE 
KBF.sub.4 
10 DISC 1.06 304SS 12 
20 60 A E NONE 
CRYOLITE 
10 BELT 1.41 304SS 20 
21 60 A E C CRYOLITE + 
10 BELT 1.41 304SS 30 
KBF.sub.4 
22 80 A B C KBF.sub.4 
100 BELT 1.06 304SS 30 
23 80 B C NONE 
KBF.sub.4 
100 BELT 1.06 304SS 30 
24 80 A B C KBF.sub.4 
10 BELT 1.06 304SS 30 
25 80 A C NONE 
KBF.sub.4 
10 BELT 1.06 304SS 30 
26 80 A B D KBF.sub.4 
10 BELT 1.06 304SS 30 
27 80 A B NONE 
NONE 10 BELT 1.06 304SS 30 
28 80 A B C KBF.sub.4 
100 BELT 1.06 TITANIUM 
15 
29 80 A B C KBF.sub.4 
10 BELT 1.06 TITANIUM 
20 
30 80 A B C KBF.sub.4 
100 BELT 1.06 1018MS 40 
31 80 A B C KBF.sub.4 
10 BELT 1.06 1018MS 40 
32 50 A B C.sup.2 
NaCl 100 DISC 1.06 304SS 12 
33 50 A B C KBF.sub.4 
100 DISC 1.06 304SS 12 
34 50 A B C.sup.2 
CaCO.sub.3 
100 DISC 1.06 304SS 12 
35 50 A B GEON.sup.1 
100 DISC 1.06 304SS 12 
36 50 A B C.sup.2 
Na.sub.2 CO.sub.3 
100 DISC 1.06 304SS 12 
37 50 A B C.sup.2 
SULFUR 100 DISC 1.06 304SS 12 
38 50 A B C.sup.2 
K.sub.2 TiF.sub.6 
100 DISC 1.06 304SS 12 
39 50 A B C.sup.2 
K.sub.2 HPO.sub.4 
100 DISC 1.06 304SS 12 
40 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
41 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
42 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
43 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
44 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
45 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
46 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
47 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
48 50 A B C KBF.sub.4 
10 DISC 0.92 304SS 12 
49 50 A B C KBF.sub.4 
10 DISC 0.92 304SS 12 
50 50 A B C KBF.sub.4 
10 DISC 0.92 304SS 12 
51 50 A B C KBF.sub.4 
10 DISC 0.92 304SS 12 
52 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
53 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
54 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
55 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
56 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
57 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
58 50 A B C KBF.sub.4 
20 DISC 1.76 304SS 30 
59 50 A B C KBF.sub. 4 
20 DISC 1.76 304SS 30 
60 50 A B C KBF.sub.4 
20 DISC 1.76 304SS 30 
61 50 A B C KBF.sub.4 
20 DISC 1.76 304SS 30 
62 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
63 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
64 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
65 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
66 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
67 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
68 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
69 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
70 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
71 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
72 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
73 36 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
74 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
75 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
76 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
77 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
78 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
79 50 A B C KBF.sub.4 
100 DISC 0.92 304SS 12 
80 50 A B C KBF.sub.4 
20 BELT 1.76 304SS 30 
81 50 A B C KBF.sub.4 
20 BELT 1.76 304SS 30 
82 50 A B C KBF.sub.4 
100 BELT 1.76 304SS 30 
83 50 A B C KBF.sub.4 
20 BELT 1.76 304SS 30 
84 50 A B C KBF.sub.4 
20 BELT 1.76 304SS 30 
85 36 A A C KBF.sub.4 
15 BELT 1.76 Waspalloy 
15 
__________________________________________________________________________ 
.sup.1 Polyvinylidene chloride available under the trade designation 
"Geon" 660X1. 
.sup.2 Resin C was modified by substituting the designated grinding aid 
for KBF.sub.4. 
TABLE III 
__________________________________________________________________________ 
Cut 
Al.sub.2 O.sub.3 
Y.sub.2 O.sub.3 
Other 
Other Relative 
No. (%) (%) 
(type) 
(%) Total(g) 
(%) Control 
__________________________________________________________________________ 
1 97 3 86 80 CUBITRON 
2 94.5 
5.5 104 95 CUBITRON 
3 91.5 
8.5 130 125 CUBITRON 
4 89 11 127 120 CUBITRON 
5 86 14 140 130 CUBITRON 
6 83 17 167 150 CUBITRON 
7 85 15 243 177 NORZON 
8 82.5 
17.5 253 185 NORZON 
9 80 20 217 158 NORZON 
10 78.5 
22.5 154 112 NORZON 
11 75 25 144 105 NORZON 
12 83 17 1760 132 NORZON 
13 83 17 1060 79 NORZON 
14 83 17 1578 134 NORZON 
15 83 17 1055 90 NORZON 
16 83 17 1097 143 NORZON 
17 83 17 701 92 NORZON 
18 83 17 357 202 NORZON 
19 83 17 205 116 NORZON 
20 85 15 605 42 NORZON 
21 85 15 1204 97 NORZON 
22 85 15 512 Fused Al.sub.2 O.sub.3 
23 85 15 316 Fused Al.sub.2 O.sub.3 
24 85 15 333 Fused Al.sub.2 O.sub.3 
25 85 15 200 Fused Al.sub.2 O.sub.3 
26 85 15 318 Fused Al.sub.2 O.sub.3 
27 85 15 118 Fused Al.sub.2 O.sub.3 
28 85 15 208 Fused Al.sub.2 O.sub.3 
29 85 15 152 Fused Al.sub.2 O.sub.3 
30 85 15 159 Fused Al.sub.2 O.sub.3 
31 85 15 122 Fused Al.sub.2 O.sub.3 
32 85 15 112 223 Fused Al.sub.2 O.sub.3 
33 85 15 263 526 Fused Al.sub.2 O.sub.3 
34 85 15 100 200 Fused Al.sub.2 O.sub.3 
35 85 15 226 450 Fused Al.sub.2 O.sub.3 
36 85 15 89 178 Fused Al.sub.2 O.sub.3 
37 85 15 267 533 Fused Al.sub.2 O.sub.3 
38 85 15 240 480 Fused Al.sub.2 O.sub.3 
39 85 15 96 192 Fused Al.sub.2 O.sub.3 
40 82.5 
17.5 419 331 NORZON 
41 85 15 401 317 NORZON 
42 87.5 
12.5 440 348 NORZON 
43 90 10 400 316 NORZON 
44 84.4 
15.6 300 203 NORZON 
45 86.6 
13.4 301 204 NORZON 
46 89.2 
10.8 297 201 NORZON 
47 90.7 
9.3 329 222 NORZON 
48 84.4 
15.6 182 131 Fused Al.sub.2 O.sub.3 
49 86.6 
13.4 177 127 Fused Al.sub.2 O.sub.3 
50 89.2 
10.8 222 160 Fused Al.sub.2 O.sub.3 
51 90.7 
9.3 194 139 Fused Al.sub.2 O.sub.3 
52 94.3 
5.7 271 156 NORZON 
53 95.6 
4.4 275 158 NORZON 
54 96.1 
3.9 274 157 NORZON 
55 96.4 
3.6 273 157 NORZON 
56 97.7 
2.3 243 140 NORZON 
57 98.7 
1.3 211 121 NORZON 
58 84.4 
15.6 1701 113 NORZON 
59 86.6 
13.4 1661 111 NORZON 
60 89.2 
10.8 1509 100 NORZON 
61 90.7 
9.3 1387 92 NORZON 
62 90 10 294 170 NORZON 
63 90.9 
8.08 
MgO 1.01 
324 188 NORZON 
64 91.84 
6.25 
MgO 2.04 
269 156 NORZON 
65 92.78 
4.12 
MgO 3.09 
293 170 NORZON 
66 93.75 
2.1 
MgO 4.15 
249 144 NORZON 
67 80 10 Alpha 
10.0 
234 133 NORZON 
68 90.9 
8.1 
MgO 1.0 424 243 NORZON 
69 90.9 
8.1 
MgO 1.0 350 201 NORZON 
70 90.9 
8.1 
MgO 1.0 425 244 NORZON 
71 90.9 
8.1 
MgO 1.0 431 247 NORZON 
72 86.5 
8.0 
ZrO.sub.2 
5.6 303 174 NORZON 
73 90 10 386 221 NORZON 
74 98.5 
1.5 140 100 NORZON 
75 98.75 
1.25 112 81 NORZON 
76 99 1 92 66 NORZON 
77 99.25 
0.75 77 55 NORZON 
78 99.5 
0.5 75 53 NORZON 
79 99.75 
0.25 54 39 NORZON 
80 97 2 MgO 1 1623 113 NORZON 
81 94 2 MgO 4 1738 121 NORZON 
82 92.5 
5 MgO 2.5 1943 135 NORZON 
83 91 8 MgO 1 2060 143 NORZON 
84 88 8 MgO 4 1995 139 NORZON 
85 85 15 430 198 NORZON 
__________________________________________________________________________