Surface-coating material, cutting tool in which said material is used, and working machine in which said material is used

The present invention provides a surface-coating material capable of exhibiting high peeling resistance and high chipping resistance. A surface-coating material is provided with a base material, a bottom layer, and a top layer. The base material comprises high-speed tool steel or cemented carbide. The bottom layer is provided on the surface of the base material and comprises at least one nitride of titanium, aluminum, chromium, and zirconium. The top layer is provided on the surface of the bottom layer and is formed by alternatingly laminating an A layer and/or a B layer. The A layer comprises a nitride of aluminum, chromium, and silicon. The B layer comprises a nitride of aluminum, chromium, and yttrium.

TECHNICAL FIELD

The present invention relates to a surface-coating material, a cutting tool in which the material is used, and a working machine in which the material is used.

BACKGROUND ART

As a cutting tool with which cutting is performed in a working machine, cutting tools obtained by forming a high-hardness coating film on a surface of a base material using physical vapor deposition represented by ion plating have been developed. Among these cutting tools, the practical use of a cutting tool obtained by forming a layer formed of a metal nitride such as TiN or TiAlN on a surface of a base material has progressed the most.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, when the above-described cutting tool is used in a high-temperature range of higher than 800° C., oxidation of the metal nitride is started, and thus there is a problem in that the cutting tool cannot be used for a long period of time. Therefore, as a cutting tool which can be used in a high-temperature range, cutting tools obtained by providing a surface-coating material such as an AlCrN coating film or an (AlCrM)N coating film (M represents at least one element or two or more elements selected from elements other than Cr in Groups 4a, 5a, and 6a of the periodic table, B, Si, and Y) on a surface of a base material are considered (for example, refer to the above-described PTLs 1 to 4).

However, the cutting tools obtained by providing the surface-coating material on the surface of the base material have a problem in the adhesion of the surface-coating material. In addition, under a cutting condition of high-speed feeding where a high load is locally applied to a cutting blade portion along with a large amount of heat generation; peeling or chipping (small cracking) occurs in the surface-coating material in the early stage. Therefore, there is a problem in that the lifetime ends within a relatively short period of time, and superior wear resistance in a high-temperature range which is a intrinsic characteristic of the surface-coating material cannot be sufficiently exhibited.

The above-described problems may occur in the same way as described above not only in the above-described cutting tools used in a working machine but also in components and dies to which a surface-coating material requiring superior wear resistance in a high-temperature range is applied.

Accordingly, the invention has been made in order to solve the above-described problems, and an object thereof is to provide a surface-coating material capable of exhibiting high peeling resistance and high chipping resistance, a cutting tool in which the material is used, and a working machine in which the material is used.

Solution to Problem

According to a first aspect of the present invention for solving the above-described problems, there is provided a surface-coating material including a top layer on a surface of the surface-coating material, in which in the top layer, one or more A layers, which contain a nitride of aluminum, chromium, and silicon and one or more B layers, which contain a nitride of aluminum, chromium, and yttrium, are alternately laminated, and the top layer is provided on a surface of a metal nitride.

According to a second aspect of the present invention for solving the above-described problems, in the surface-coating material according to the first aspect, the A layer satisfies 0.15≦a≦0.59 and 0.01≦b≦0.1 by atomic ratio when represented by a compositional formula (Al1-a-bCraSib)N, and the B layer satisfies 0.15≦c≦0.60 and 0.005≦d≦0.1 by atomic ratio when represented by a compositional formula (Al1-c-dCrcYd) N.

According to a third aspect of the present invention for solving the above-described problems, in the surface-coating material according to the first or second aspect, each of the A layer and the B layer has a thickness of 240 nm or less.

According to a fourth aspect of the present invention for solving the above-described problems, in the surface-coating material according to the first aspect, the B layer further contains a nitride of silicon.

According to a fifth aspect of the present invention for solving the above-described problems, in the surface-coating material according to the fourth aspect, the A layer satisfies 0.15≦a≦0.60 and 0.01≦b≦0.1 by atomic ratio when represented by a compositional formula (Al1-a-bCraSib)N, and the B layer satisfies 0.15≦c≦0.60, 0.01≦d≦0.1, and 0.005≦e≦0.1 by atomic ratio when represented by a compositional formula (Al1-c-d-eCrcSidYe)N.

According to a sixth aspect of the present invention for solving the above-described problems, in the surface-coating material according to the fourth or fifth aspect, each of the A layer and the B layer has a thickness of 150 nm or less.

According to a seventh aspect of the present invention for solving the above-described problems, in the surface-coating material according to any one of the first to sixth aspects, the top layer has a thickness of 2 μm to 8 μm.

According to an eighth aspect of the present invention for solving the above-described problems, in the surface-coating material according to any one of the first to seventh aspects, the metal nitride contains a nitride of at least one element of titanium, aluminum, chromium, and zirconium.

According to a ninth aspect of the present invention for solving the above-described problems, in the surface-coating material according to any one of the first to eighth aspects, the metal nitride is provided on a surface of a base material.

According to a tenth aspect of the present invention for solving the above-described problems, in the surface-coating material according to the ninth aspect, the base material contains high-speed tool steel or cemented carbide.

According to an eleventh aspect of the present invention for solving the above-described problems, there is provided a cutting tool including the surface-coating material according to any one of the first to tenth aspects.

According to a twelfth aspect of the present invention for solving the above-described problems, there is provided a working machine including a cutting tool that includes the surface-coating material according to any one of the first to tenth aspects.

Advantageous Effects of Invention

The surface-coating material according to the present invention can exhibit high peeling resistance and high chipping resistance. Therefore, superior wear resistance in a high-temperature range which is an intrinsic characteristic of the top layer can be sufficiently exhibited.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of a surface-coating material, a cutting tool in which the material is used, and a working machine in which the material is used according to the present invention will be described based on the drawing. However, the present invention is not limited to only the following embodiments described based on the drawing.

An embodiment of the surface-coating material, the cutting tool in which the material is used, and the working machine in which the material is used according to the present invention will be described based onFIG. 1.

As shown inFIG. 1, a surface-coating material10according to the embodiment includes a base material11, a bottom layer12, and a top layer13. The base material11contains high-speed tool steel or cemented carbide. The bottom layer12is provided on a surface of the base material11and contains at least one of nitrides (N) of titanium (Ti), aluminum (Al), chromium (Cr), and zirconium (Zr). The top layer13is provided on a surface of the bottom layer12and is formed by alternately laminating one or more (in the drawing, seven) A layers14and one or more (in the drawing, seven) B layers15. The A layer14contains a nitride (N) of aluminum (Al), chromium (Cr), or silicon (Si). The B layer15contains a nitride (N) of aluminum (Al), chromium (Cr), or yttrium (Y).

In addition, it is preferable that the B layer15further contains a nitride (N) of silicon (Si).

The surface-coating material10can be easily manufactured using a method including: providing the bottom layer12containing the above-described composition on the base material11using physical vapor deposition (PVD) such as sputter deposition or ion plating; and then providing the top layer13thereon, in which the top layer13is formed by alternately laminating the one or more A layers14and the one or more B layers15.

The surface-coating material10has an alternately laminated structure (multilayer structure) of the A layers containing (AlCrSi)N and the B layers15containing (AlCrY)N or (AlCrSiY)N. As a result, peeling resistance and chipping resistance of the top layer13are improved, and superior wear resistance in a high-temperature range which is an intrinsic characteristic of a hard coating film can be sufficiently exhibited, the hard coating film being a composite nitride containing Al, Cr, Si, and Y as essential components.

Further, the bottom layer12contains a nitride (for example, TiN, CrN, ZrN, or TiAlN) of at least one element of titanium (Ti), aluminum (Al), chromium (Cr), and zirconium (Zr). As a result, the adhesion between the bottom layer12and the base material11(cutting tool surface) can be improved.

Accordingly, in a cutting tool and a working machine in which the surface-coating material10according to the embodiment is used, even when a condition of locally applying a high load is used, the peeling and chipping of the top layer13can be prevented over a long period of time. Therefore, superior wear resistance in a high-temperature range which is an intrinsic characteristic of the top layer13can be sufficiently exhibited.

It is preferable that the B layer15satisfies 0.15≦c≦0.6 and 0.005≦d≦0.1 by atomic ratio when represented by a compositional formula (Al1-c-dCrcYd)N. The reason is as follows. It is not preferable that the composition ratio of c is lower than 0.15 because, as the element ratio of aluminum (Al) is increased, particularly, higher than 0.75, the hardness of the B layer15is likely to be decreased. It is not preferable that the composition ratio of c is higher than 0.6 because, as the element ratio of chromium (Cr) is increased, the hardness of the B layer15is likely to be decreased. It is not preferable that the composition ratio of d is lower than 0.005 because it is difficult to obtain the effect of improving heat resistance by the addition of yttrium (Y). It is not preferable that the composition ratio of d is higher than 0.1 because it is difficult to manufacture the B layer15.

When the B layer15can be represented by a composition formula (Al1-c-dCrcYd)N (wherein 0.15≦c≦0.6 and 0.005≦d≦0.1 are satisfied by atomic ratio), it is preferable that the A layer14satisfies 0.15≦a≦0.59 and 0.01≦b≦0.1 by atomic ratio when represented by a compositional formula (Al1-a-bCraSib)N. The reason is as follows. It is not preferable that the composition ratio of a is lower than 0.15 because, as the element ratio of aluminum (Al) is increased, particularly, higher than 0.75, the hardness of the A layer14is likely to be decreased. It is not preferable that the composition ratio of a is higher than 0.59 because, as the element ratio of chromium (Cr) is increased, the hardness of the A layer14is likely to be decreased. It is not preferable that the composition ratio of b is lower than 0.01 because it is difficult to obtain the effect of improving heat resistance by the addition of silicon (Si). It is not preferable that the composition ratio of b is higher than 0.1 because it is difficult to manufacture the A layer14.

It is preferable that the B layer15satisfies 0.15≦c≦0.60, 0.01≦d≦0.1, and 0.005≦e≦0.1 by atomic ratio when represented by a compositional formula (Al1-c-d-eCrcSidYe)N. The reason is as follows. It is not preferable that the composition ratio of c is lower than 0.15 because, as the element ratio of aluminum (Al) is increased, particularly, higher than 0.75, the hardness of the B layer15is likely to be decreased. It is not preferable that the composition ratio of c is higher than 0.60 because, as the element ratio of chromium (Cr) is increased, the hardness of the B layer15is likely to be decreased. It is not preferable that the composition ratio of d is lower than 0.01 because it is difficult to obtain the effect of improving heat resistance by the addition of silicon (Si). It is not preferable that the composition ratio of d is higher than 0.1 because it is difficult to manufacture the B layer15due to unstable target discharge during deposition. It is not preferable that the composition ratio of e is lower than 0.005 because it is difficult to obtain the effect of improving wear resistance by the addition of yttrium (Y). It is not preferable that the composition ratio of e is higher than 0.1 because it is difficult to manufacture the B layer15due to unstable target discharge during deposition.

When the B layer15can be represented by a composition formula (Al1-c-d-eCrcSidYe)N(wherein 0.15≦c≦0.60, 0.01≦d≦0.1, and 0.005≦e≦0.1 are satisfied by atomic ratio), it is preferable that the A layer14satisfies 0.15≦a≦0.60 and 0.015≦b≦0.1 by atomic ratio when represented by a compositional formula (Al1-a-bCraSib)N. The reason is as follows. It is not preferable that the composition ratio of a is lower than 0.15 because, as the element ratio of aluminum (Al) is increased, particularly, higher than 0.75, the hardness of the A layer14is likely to be decreased. It is not preferable that the composition ratio of a is higher than 0.60 because, as the element ratio of chromium (Cr) is increased, the hardness of the A layer14is likely to be decreased. It is not preferable that the composition ratio of b is lower than 0.01 because it is difficult to obtain the effect of improving heat resistance by the addition of silicon (Si). It is not preferable that the composition ratio of b is higher than 0.1 because it is difficult to manufacture the A layer14.

When the A layer14contains (AlCrSi)N, and when the B layer contains (AlCrY)N, it is preferable that each of the A layer14and the B layer15has a thickness of 240 nm or less (particularly 200 nm or less). The reason is as follows. It is not preferable that the thickness of each of the A layer14and the B layer15is more than 240 nm because plastic deformability in the A layer14(single layer) and the B layer15(single layer) is decreased, and peeling resistance and chipping resistance obtained by the alternately laminated structure are likely to be decreased.

When the A layer14contains (AlCrSi)N, and when the B layer15contains (AlCrSiY)N, it is preferable that each of the A layer14and the B layer15has a thickness of 150 nm or less (particularly 100 nm or less). The reason is as follows. It is not preferable that the thickness of each of the A layer14and the B layer15is more than 150 nm because plastic deformability in the A layer14(single layer) and the B layer15(single layer) is decreased, and peeling resistance and chipping resistance obtained by the alternately laminated structure are likely to be decreased.

It is preferable that the A layer14and the B layer15have the same thickness. The reason is as follows. It is not preferable that the A layer14and the B layer15have different thicknesses because peeling properties between the A layer14and the B layer15are likely to be increased.

It is preferable that the top layer13has a thickness of 2 μm to 8 μm (particularly, 3 μm to 6 μm). The reason is as follows. It is not preferable that the thickness of the top layer13is more than 8 μm because, under a cutting condition of high-speed feeding, particularly, in interrupted cutting, peeling and chipping are likely to occur in a cutting blade portion, and the lifetime ends within a relatively short period of time. It is not preferable that the thickness of the top layer13is less than 2 μm because the wear resistance of the top layer cannot be sufficiently exhibited, and thus it is difficult to secure cutting performance over a long period of time.

It is preferable that the base material11contains high-speed tool steel or cemented carbide. The reason is as follows. By the base material11containing high-speed tool steel or cemented carbide, under a cutting condition of high-speed feeding, particularly, in interrupted cutting, superior wear resistance can be exhibited without peeling and chipping in the bottom layer12, and thus stable cutting performance can be exhibited over a long period of time.

In addition, the cutting tool is not particularly limited as long as it is a tool for performing cutting, but is particularly preferably a gear cutting tool such as a hob cutter or a pinion cutter, or a broach cutter. The working machine is not particularly limited as long as it can perform cutting, but is particularly preferably a gear cutting machine such as a bobbing machine or a gear shaping machine, or a broaching machine.

Another Embodiment

In the above description of the embodiment, the base material11containing high-speed tool steel or cemented carbide is applied to the surface-coating material10. However, a base material containing another metal material (for example, various special steels and alloy steels) can be applied to the surface-coating material10.

In the above description of the embodiment, the surface-coating material10includes the top layer13obtained by alternately laminating the one or more A layers14and the one or more B layers15, in which the B layer15is provided on the surface of the A layer14. However, the surface-coating material10may include the top layer13obtained by alternately laminating the one or more A layers14and the one or more B layers15, in which the A layer14is provided on the surface of the B layer15.

EXAMPLES

Hereinafter, examples will be described which were performed to verify the effects of the surface-coating material, the cutting tool in which the material is used, and the working machine in which the material is used according to the present invention. However, the present invention is not limited to only the following examples described below based on various data.

In this test, test samples, comparative samples, and reference samples were prepared by providing surface-coating materials shown in Table 1 below on a surface of a formed fly tool (cutting tool) including high-speed tool steel SKH 55 as a base material using an arc ion plating apparatus. Regarding the test samples, the comparative samples, and the reference samples, a cutting test was performed under the following cutting conditions to measure the width of flank wear of the tool.

Cutting method: interrupted cutting

Depth of cut: 1 mm

Cutting fluid: air blow

Length of cut: 1 m

As shown in Tables 2 and 3, it was verified that the peeling resistance and chipping resistance of the base material11or the top layer13can be improved by using the surface-coating material obtained by providing the top layer on the surface of the metal nitride, in which the top layer is formed by alternately laminating one or more A layers containing a nitride (N) of aluminum (Al), chromium (Cr), and silicon (Si) and one or more B layers containing a nitride (N) of aluminum (Al), chromium (Cr), and yttrium (Y). As a result, superior wear resistance in a high-temperature range which is an intrinsic characteristic of the top layer13can be sufficiently exhibited, the top layer13being a composite nitride containing aluminum (Al), chromium (Cr), silicon (Si), and yttrium (Y) as major components.

In this test, test samples, comparative samples, and reference samples were prepared by providing surface-coating materials shown in Table 4 below on a surface of a formed fly tool (cutting tool) including high-speed tool steel SKH 55 as a base material using an arc ion plating apparatus. Regarding the test samples, the comparative samples, and the reference samples, a cutting test was performed under the same cutting conditions as those of the above verification test 1 to measure the width of flank wear of the tool.

As shown in Tables 5 and 6, it was verified that the peeling resistance and chipping resistance of the base material11or the top layer13can be improved by using the surface-coating material obtained by providing the top layer on the surface of the metal nitride, in which the top layer is formed by alternately laminating one or more A layers containing a nitride (N) of aluminum (Al), chromium (Cr), and silicon (Si) and one or more B layers containing a nitride (N) of aluminum (Al), chromium (Cr), silicon (Si) and yttrium (Y). As a result, superior wear resistance in a high-temperature range which is an intrinsic characteristic of the top layer13can be sufficiently exhibited, the top layer13being a composite nitride containing aluminum (Al), chromium (Cr), silicon (Si), and yttrium (Y) as major components.

INDUSTRIAL APPLICABILITY

The surface-coating material, the cutting tool in which the material is used, and the working machine in which the material is used according to the present invention can exhibit high peeling resistance and high chipping resistance. Therefore, superior wear resistance in a high-temperature range which is an intrinsic characteristic of the top layer can be sufficiently exhibited. Accordingly, the present invention has extremely high industrial applicability.

REFERENCE SIGNS LIST