JPS6136071B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surface-coated superhard alloy member having a hard surface layer with excellent high-temperature wear resistance and particularly suitable for use as cutting tools and wear-resistant tools. Conventionally, the hard layer has mainly been made of carbides, nitrides, and metals of groups 4a, 5a, and 6a of the periodic table of elements.
and carbonitrides, and the binder phase is mainly one or two or more iron group metals, or one or two or more iron group metals and chromium. Surface-coated cemented carbide members, which are made by coating a hard surface layer of various materials on the surface of a superhard alloy base made of one or more of group metals and Al, are used as cutting tools and wear-resistant tools. It is well known that this is the case. However, these conventional surface-coated superhard alloy members do not necessarily have a satisfactory tool life because the hard surface layer does not have sufficient high-temperature wear resistance. Therefore, recently, attempts have been made to use silicon carbide (hereinafter referred to as SiC), which has excellent high-temperature wear resistance (high-temperature hardness), as a hard surface layer. On the other hand, it is brittle and has poor adhesion to the cemented carbide substrate,
Furthermore, using a chemical vapor deposition method, SiC is deposited on the surface of the substrate.
When forming the layer, Si diffuses into the substrate and combines with iron group metals to form a brittle compound, which deteriorates the toughness of the substrate. This resulted in peeling and delamination, making it difficult to expect long-term use. Therefore, from the above-mentioned viewpoint, the present inventors aimed to form a SiC layer having excellent high-temperature wear resistance on the surface of the above-mentioned superhard alloy substrate with good adhesion and maintaining toughness. As a result of research, it was found that, prior to forming a SiC layer on the surface of the substrate, Ti carbides, nitrides, and oxides, or two or more of these, were first used to impart toughness to the entire hard surface layer. A hard layer with an average layer thickness of 1.5 to 15 μm is formed by a single layer of one type of solid solution or a multilayer of two or more types of solid solutions, and then the upper layer of the hard layer is
A Si diffusion layer is formed with an average layer thickness of ~5μm, and in this state
When the SiC layer is formed, this SiC layer adheres extremely firmly to the Si diffusion layer, so the resulting surface-coated cemented carbide member has excellent high-temperature wear resistance and toughness. Got tired,
It was discovered that when used as a cutting tool or a wear-resistant tool, it exhibits excellent cutting and wear-resistant performance over an extremely long period of time. This invention was made based on the above knowledge, and it is found that the hard phase is mainly in the periodic table of elements.
It is composed of one or more types of carbides, nitrides, and carbonitrides of metals of groups 4a, 5a, and 6a, and the binder phase is mainly one or more types of iron group metals, Alternatively, Ti carbides, nitrides, and oxides may be added to the surface of a superhard alloy substrate composed of one or more iron group metals and one or more chromium group metals and Al. average layer thickness consisting of a single layer or a multilayer of two or more of these solid solutions: an inner layer of 1 to 10 μm, and an average layer consisting of an inner layer in which Si is diffused. A surface-coated superhard alloy member for cutting tools and wear-resistant tools formed by forming a hard surface layer composed of a Si diffusion intermediate layer with a thickness of 0.5 to 5 μm and an outer layer made of SiC with an average layer thickness of 1 to 10 μm. It has the following characteristics. Next, the reason why the average layer thicknesses of the inner layer, Si diffusion intermediate layer, and outer layer constituting the hard surface layer of the present invention are limited as described above will be explained. (a) Inner layer The inner layer has the function of imparting toughness to the entire hard surface layer and firmly adhering it to the substrate surface, but if the average layer thickness is less than 1 μm, the desired effect cannot be obtained. On the other hand, even if the average layer thickness exceeds 10 .mu.m, no further improvement effect will be obtained due to the above action, so the average layer thickness was set at 1 to 10 .mu.m. (b) Si diffusion intermediate layer The Si diffusion intermediate layer has the effect of strongly bonding with the outer SiC layer, but the average layer thickness is
If the thickness is less than 0.5 μm, it will not be possible to secure the desired strong adhesion with the outer layer, while if the average layer thickness exceeds 10 μm, the entire surface coating layer will tend to become brittle. The average layer thickness was determined to be 0.5 to 5 μm. (c) Outer layer The SiC layer as the outer layer has extremely excellent high-temperature wear resistance, but if the average layer thickness is less than 1 μm, the desired high-temperature wear resistance cannot be secured; on the other hand, if the average layer thickness exceeds 10 μm If the thickness is increased, the toughness of the surface coating layer will be impaired.
Since chipping and peeling phenomena occur during practical use, the average layer thickness was set at 1 to 10 μm. Next, the surface-coated cemented carbide member of the present invention will be specifically explained with reference to Examples. Example 1 Cutting chips having the chemical compositions shown in Table 1 and shapes specified in JIS/SNP432 were prepared as superhard alloy substrates, and the surfaces of these cutting chips were coated using chemical vapor deposition. Then, under the same conditions shown in Table 1, the inner layer, Si diffused intermediate layer,
Coated cutting chips 1 to 8 of the present invention were each manufactured by forming a hard surface layer consisting of a hard surface layer and an outer layer. Table 2 shows the average layer thicknesses of the inner layer, Si-diffused intermediate layer, and outer layer that constitute the hard surface layers of coated cutting chips 1 to 8 of the present invention obtained as a result, together with the surface hardness (Vickers hardness). Ta. Next, using the coated cutting chips 1 to 8 of the present invention, workpiece material: cast iron (FC25), cutting speed: 80 m/
A cutting test was conducted under the conditions of mm, feed: 0.25 mm/rev., and depth of cut: 1.5 mm, and the cutting time until flank wear reached 0.3 mm was measured. The measurement results are shown in Table 2.

【table】

【table】

[Table] From the results shown in Table 2, coated cutting chips 1 to 8 of the present invention all showed extremely long cutting life, and commercially available super-hard alloy cutting chips with a hard surface layer showed normal cutting life under the same conditions. It is clear that the coated cutting tips of the present invention have a cutting life of 60 to 90 minutes, which is a very good value, as opposed to a cutting life of less than 30 minutes. Example 2 As in Example 1, the superhard alloy substrates each had the component composition shown in Table 3,
Cutting chips with a shape specified in JIS/SNP432 are prepared, and the inner layer, Si diffusion intermediate layer, and outer layer are coated on the surface of these cutting chips using the chemical vapor deposition method under the conditions shown in Table 3. Coated cutting chips 9 to 13 of the present invention were each manufactured by forming a hard surface consisting of: The average layer thicknesses of the inner layer, Si-diffused intermediate layer, and outer layer constituting the hard surface layers of the coated cutting chips 9 to 13 of the present invention obtained as a result are shown in Table 4 together with the surface hardness (Vickers hardness).

【table】

[Table] Next, regarding the above-mentioned coated cutting chips 9 to 13 of the present invention, work material: Al (JIS1100), cutting speed: 100
m/min, feed: 0.1mm/rev., depth of cut: 0.5mm,
A cutting test was conducted under conditions of cutting time: 30 minutes, and the surface roughness of the workpiece surface was observed. In all cases, the workpiece surface showed a clean surface, and the welding resistance in Al cutting was excellent. It was hot.

[Table] Although the above example describes the case where it is used as a cutting tool, it goes without saying that it also exhibits excellent wear resistance when used as a wear-resistant tool such as a wire drawing die or a bearing. . As mentioned above, the surface-coated superhard alloy member of the present invention has an outer layer that has excellent high-temperature wear resistance.
Since the SiC layer has a hard surface layer that firmly adheres to the substrate surface through the Si diffusion intermediate layer and inner layer, it exhibits excellent high-temperature wear resistance when used as a cutting tool or wear-resistant tool. However, it brings about industrially useful effects such as being able to be put into practical use for an extremely long period of time.

Claims (1)

[Claims] 1. The hard phase is mainly composed of one or more carbides, nitrides, and carbonitrides of metals in Groups 4a, 5a, and 6a of the Periodic Table of the Elements, and the binder phase is mainly composed of iron group metals. or one or more iron group metals and one or more of chromium group metals and Al. , Ti carbides, nitrides, and oxides, and solid solutions of two or more of these. Average layer thickness: 1 to 10.
an inner layer with an average layer thickness of 0.5 to 5 μm, consisting of an inner layer with Si diffused into the inner layer;
A surface-coated super-hard alloy member for cutting tools and wear-resistant tools, comprising a surface hard layer composed of a silicon carbide outer layer having an average layer thickness of 1 to 10 μm.