JP2000326105A - Surface coated cemented carbide cutting tool with artifical diamond coating layer having excellent adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool with an artificial diamond coating layer having excellent adhesion. SOLUTION: This surface coated cemented carbide cutting tool is provided by forming an artificial diamond coating layer or an artificial diamond carbonate coating layer of average thickness 4-5 μm on a surface of a carbide base body having a composition composed of Co of 1-20 wt.% contained as a binding phase forming component and WC and inevitable impurities as a dispersed phase forming components, wherein inside WC particles do not have substantial particle growth and maintain a sintered lump condition in a longitudinal section structure observation, while an uppermost surface portion substantially consist of WC particles and this WC particles have a board shape structure in which a crystal surface grew in such a condition that its thickness does not change in a longitudinal direction against the base body surface (100).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial diamond coating layer or an artificial diamond-like layer formed on a surface of a substrate made of a tungsten carbide-based cemented carbide (hereinafter referred to as a cemented carbide substrate) by a vapor phase synthesis method. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter, referred to as a coated cemented carbide tool) having a carbon coating layer (hereinafter, collectively referred to as a diamond coating layer) having excellent adhesion.

[0002]

2. Description of the Related Art Conventionally, C is generally used as a binder phase forming component.
o: A composition containing 1 to 20% by weight, the balance being composed of tungsten carbide (hereinafter referred to as WC) as a disperse phase forming component and unavoidable impurities, and a structure shown in a schematic diagram in FIG. (A) Surface grinding processing for dimensioning using, for example, a diamond grindstone on the surface of the as-sintered cemented carbide substrate having (magnification: 3000 times)
(B) for example in a vacuum atmosphere of ^{1 × 10- 5 ~ -3 Torr,} 1~3 to a predetermined temperature in the range of 1300 to 1500 ° C.
A heat treatment for coarsening the WC grains exposed on the substrate surface under the condition of holding for a predetermined time within the time range to improve the adhesion of the diamond coating layer (in this case, the vertical cross-sectional structure is also schematically shown in FIG. 3). As shown in the above, fine WC particles generated in the step (a) and adhering to the surface are relatively coarse WC particles.
It grows by being incorporated into grains, but the WC inside also grows and coarsens). In the state where the treatments (a) and (b) are performed, for example, it is described in JP-A-58-91100. Thermionic emission method, the microwave method described in JP-A-58-110494, and the like.
The diamond coating layer is formed to a thickness of 4 to 30 μm by using a gas phase synthesis method such as a high-frequency plasma method described in JP-A-135117.
A coated carbide tool formed with an average layer thickness of m is known, and this coated carbide tool is, for example, pure Al or Al-S
It is also well known that it is used for continuous cutting or intermittent cutting of non-metallic materials such as Al alloys such as i-alloys, non-ferrous metal materials such as Cu alloys, and carbon materials.

[0003]

On the other hand, in recent years, the use of FA in cutting equipment has been remarkable, and there has been a strong demand for labor saving in cutting work. Accordingly, the diamond coating layer of coated carbide tools has been increased in thickness, and cutting has been required. Processing tends to be faster,
In the above-mentioned conventional coated carbide tool, when this is used for high-speed cutting or when the diamond coating layer is thickened with an average layer thickness exceeding 50 μm even under ordinary cutting conditions, the diamond coating layer is At present, the diamond coating layer is apt to peel off due to insufficient adhesion, and the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, a study was conducted to improve the adhesion of the diamond coating layer to the surface of the cemented carbide substrate, and as a result, the above (a) and ( Instead of the treatment (b) of the treatment (b), the super-hard substrate is charged into, for example, a microwave plasma generator, and the reaction atmosphere is hydrogen, the reaction atmosphere pressure is 5 to 100 Torr, and the surface temperature of the super-hard substrate : 1100 to 1300 ° C, output: 100 to 8000 W, processing time: 5 to 30 hours. When the plasma treatment is performed under the following conditions, the resulting cemented carbide substrate has the same longitudinal sectional structure (magnification: 3000 times) as in FIG. As shown in the mimetic diagram, the outermost surface portion is substantially composed of only WC grains, and the WC grains have a (100) crystal plane with no change in thickness in the longitudinal direction with respect to the substrate surface. It has a grown plate-like shape. The inner WC grains have substantially no grain growth and have a structure that retains a bulk shape as sintered, and a diamond coating layer is formed on the surface of the WC grains by a normal gas phase synthesis method. Coated carbide tools
Since the diamond coating layer becomes extremely firmly adhered to the surface of the cemented carbide substrate, even if it is used for high-speed cutting, the thickness of the diamond coating layer is further increased to an average thickness exceeding 50 μm. In addition, they have obtained a research result that the diamond coating layer exhibits excellent cutting performance for a long period of time without peeling.

The present invention has been made based on the results of the above-mentioned research, and has Co: 1 as a binder phase forming component.
-20% by weight, with the balance consisting of WC as an indispensable phase-forming component and unavoidable impurities, and observation of the longitudinal cross-sectional structure. On the other hand, the outermost surface portion is substantially composed of only WC grains, and the WC grains have a plate-like shape in which a (100) crystal plane has grown in a state in which the thickness does not change in the longitudinal direction with respect to the substrate surface. The present invention is characterized by a coated carbide tool having a diamond coating layer having excellent adhesion, wherein a diamond coating layer is formed with an average layer thickness of 4 to 500 μm on the surface of a cemented carbide substrate having the structure presented.

[0006] In the coated carbide tool of the present invention,
The reason why the Co content of the cemented carbide substrate is set to 1 to 20% by weight is that if the content is less than 1% by weight, the sinterability deteriorates and the desired strength cannot be ensured. If it exceeds 20% by weight, the heat-resistant plastic deformation property is sharply reduced, and the substrate is significantly deformed in high-speed cutting accompanied by high heat generation, which causes peeling of the diamond coating layer. The reason for setting the average layer thickness to 4 to 500 μm is that
If the average layer thickness is less than 4 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 500 μm, the diamond coating layer itself tends to chip or chip. It is.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide tool of the present invention will be specifically described with reference to examples. WC powder having an average particle diameter of 1.3 μm and Co powder having an average particle diameter of 1.5 μm were used as the raw material powders. , Wet mixing in a ball mill for 72 hours, drying and
The green compact was press-molded at a pressure of on / cm ² , and the green compact was pressed in a vacuum atmosphere of 1 × 10 ⁻² Torr,
Sintered at a predetermined temperature in the range of 00 to 1500 ° C. for one hour, subjected to grinding, and subjected to ISO standard SPG
Each of the super-hard substrates having a chip shape of N120408 was manufactured, and then these super-hard substrates were charged into a usual microwave plasma generator, and the reaction atmosphere was hydrogen, the reaction atmosphere pressure was 40 Torr, and the surface of the super-hard substrate was obtained. Temperature: 1250 ° C., Output: 5 KW, Processing time: Predetermined time within the range of 5 to 30 hours. Plasma treatment is performed under the following conditions. As shown in FIG. There is no substantial grain growth in the WC grains and the sintered body retains a bulk shape as it is sintered, while the outermost surface portion is substantially composed of only WC grains, and the WC grains have a thickness in the longitudinal direction with respect to the substrate surface. With no change (100)
It has a structure having a plate-like shape in which the crystal plane has grown. Then, using a microwave plasma method, which is a kind of a gas phase synthesis method, an atmospheric pressure: 20 torr, a super hard substrate surface temperature: 850 ° C., and a reaction gas Composition: CH ₄ / H ₂ = 1.5 / 100 (capacity ratio) Treatment time: predetermined time within the range of 2 to 250 hours To form a diamond coating layer having the target layer thickness shown in Table 1 under the following conditions: In this way, coated carbide tools 1 to 10 of the present invention were produced. FIGS. 1 and 2 are schematic views respectively showing the longitudinal sectional structures of the cemented carbide substrate constituting the coated carbide tool 4 of the present invention after sintering (FIG. 2) and after plasma treatment (FIG. 1). is there. For the purpose of comparison, instead of the plasma treatment performed on the above-mentioned super-hard substrate, the conditions of holding for 1 to 3 hours at 1400 ° C. in a vacuum atmosphere of 1 × 10 ⁻⁴ Torr were used. The conventional coated carbide tools 1 to 10 were respectively manufactured under the same conditions except that a heat treatment for coarsening the WC grains exposed on the substrate surface was performed. FIG. 3 is a schematic view showing a longitudinal section structure of the cemented carbide substrate constituting the conventional coated cemented carbide tool 4 after the WC grain coarsening heat treatment. Furthermore, when the average layer thickness of the diamond coating layer was measured from the longitudinal cross-sectional structure of each of the above coated coated carbide tools, the average thickness was substantially the same as the target layer thickness.

[0008] With respect to the various coated carbide tools obtained as a result, a work material: a round bar having four longitudinal grooves at regular intervals in the longitudinal direction of an Al-18% Si alloy, a cutting speed: 600 m / min, a cutting depth: 0 0.5 mm, feed: 0.1 mm / rev, cutting time: 30 minutes, wet high-speed intermittent cutting test of Al alloy containing high Si, and work material: 100 mm × 100 m of Al-18% Si alloy
Round bar with dimensions of mx 400 mm, cutting speed: 1500 m / min, depth of cut: 2 mm, feed: 0.15 mm / tooth, cutting time: 30 min. Tests were performed, and the flank wear width of the cutting edge was measured in each cutting test. Tables 1 and 2 show the measurement results.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

From the results shown in Tables 1 and 2, all of the coated carbide tools 1 to 10 of the present invention consist essentially of only WC grains on the surface of the cemented carbide substrate, and the WC grains are formed on the surface of the substrate. With no change in thickness in the vertical direction (10
0) Since the adhesion of the diamond coating layer to the surface of the superhard substrate is remarkably improved due to the structure having a plate-like shape in which the crystal plane has grown, the thickness of the diamond coating layer is further increased even when high-speed cutting is performed. Even if cutting is performed in a state where the film is thickened exceeding 50 μm in average layer thickness, the diamond coating layer does not peel, and exhibits excellent wear resistance over a long period of time,
In addition, since the WC grains inside the substrate have substantially no grain growth and maintain a bulk shape as sintered, a decrease in strength can be avoided, while the fine WC generated by grinding the surface of the super-hard substrate.
In the conventional coated carbide tools 1 to 10 made of coarse WC grains grown by taking in grains, peeling occurs in any case due to insufficient adhesion of the diamond coating layer. It is apparent that the service life is reached in time, and that the strength is reduced due to the growth of WC grains inside the substrate. As described above, the coated cemented carbide tool of the present invention can be used in high-speed cutting, and even when used in a state where the diamond coating layer is thickened with an average layer thickness exceeding 50 μm. Since the diamond coating layer that is formed exhibits excellent cutting performance without occurrence of peeling, it is possible to satisfactorily cope with FA of the cutting device and labor saving of the cutting process.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a longitudinal sectional structure of a cemented carbide substrate of a coated cemented carbide tool 4 of the present invention after a plasma treatment (magnification: 30).
00 times).

FIG. 2 is a simulated view (magnification: 3000 times) showing a longitudinal cross-sectional structure of a super hard substrate of a coated super hard tool 4 in an as-sintered state.

FIG. 3 is a schematic view showing a longitudinal sectional structure of a cemented carbide substrate of a conventional coated cemented carbide tool 4 after a WC grain coarsening heat treatment (magnification: 3000);
Times).

Claims (1)

[Claims] 1. A substrate comprising Co: 1 as a binder phase forming component.
-20% by weight, the balance consisting of tungsten carbide as a disperse phase-forming component and unavoidable impurities, and observation of the longitudinal cross-sectional structure. The shape is maintained, while the outermost surface portion is substantially composed of only tungsten carbide grains, and the (100) crystal plane has grown on the tungsten carbide grains in a state in which the thickness does not change in the longitudinal direction with respect to the substrate surface. An artificial diamond coating layer formed by forming an artificial diamond coating layer or an artificial diamond-like carbon coating layer with an average thickness of 4 to 500 μm on the surface of a tungsten carbide-based cemented carbide substrate having a plate-like structure is excellent. Surface coated cemented carbide cutting tool with excellent adhesion.