JPH0365431B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a wear-resistant part consisting of a base material and a wear-resistant coating layer covering the surface of the base material, and more specifically, to a wear-resistant part that enables the coating layer to exhibit its usefulness to a higher degree. Concerning wear parts. [Technical background of the invention and its problems] Abrasion resistance is required as a characteristic of various sliding parts such as compressor blades. In order to meet this requirement, the surface of a base material made of stainless steel or the like has been subjected to nitriding, carburizing, boriding, etc. to increase the hardness of the surface. However, the hardened surface layer in this case had a Witzkers hardness (Hv) of about 500 to 1000, which was not necessarily sufficient hardness and did not provide satisfactory results in terms of wear resistance. Therefore, recently, TiN is applied directly to the surface of the base material.
A coating layer is formed by coating a ceramic material such as TiC or SiC with a thickness of several micrometers. In this case, the hardness of the ceramic coating layer formed is as high as about 2000 Hv, so it is fully satisfactory in terms of wear resistance. However, in this case, since the thermal expansion coefficients of the base material and the ceramic coating layer differ depending on the case, there is a problem in the adhesion between the two, and phenomena such as peeling are likely to occur. In addition, the thickness of the coating layer is extremely thin, a few μm, and the base material is extremely soft, for example, with Hv of about 200 in the case of iron, so when an external force is applied to the coating layer, the base material cannot resist the external force and eventually However, there was a problem in that phenomena such as breakage occurred, and the coating layer, which is extremely useful in terms of wear resistance, was not sufficiently effective. [Object of the Invention] The object of the present invention is to provide a wear-resistant part that can eliminate the above-mentioned drawbacks and fully exhibit the effects of the ceramic coating layer. [Summary of the Invention] In the course of intensive research to achieve the above object, the inventor of the present invention did not directly form a ceramic coating layer on the surface of the base material, but instead applied a surface hardening treatment to the surface of the base material. If the surface is hardened and then a ceramic coating layer is formed on this hardened layer, even if an external force is applied to the coating layer, the hardened layer will be hard and will act as a protective wall against the soft base material body. The inventors came up with the idea that the wear-resistant parts obtained would not be damaged by acting as an anti-wear component, and developed the wear-resistant parts of the present invention. That is, the wear-resistant parts of the present invention include a base material made of iron or an iron-based alloy, titanium or a titanium-based alloy, or aluminum or an aluminum-based alloy, and a surface of the base material that is nitrided, carburized, or borided. A hardened layer formed by performing any of the surface hardening treatments, and a nitride or carbide of any element belonging to group a, group a, group a of the periodic table, silicon or boron formed on the surface of the hardened layer. or a wear-resistant part comprising a coating layer consisting of any layer or composite layer of a boride, characterized in that the coating layer is formed by a plasma chemical vapor deposition method (PCVD method). do. First, the base material is iron (Fe), Fe-based alloys such as stainless steel, titanium (Ti), etc.
Alternatively, it is a Ti-based alloy such as Ti-6Al-4V, aluminum (Al), or an Al-based alloy such as Al-Cu-based or Al-Mg-based. Among these materials, Fe
Alternatively, Fe-based alloys are particularly preferred because they allow easy formation of a hardened layer on their surfaces. A surface hardening treatment is performed on the surface of the base material described above to form a hardened layer of a predetermined thickness. As the surface hardening treatment, any one of nitriding treatment, carburizing treatment, and boriding treatment, which are commonly used as surface hardening methods, is appropriately selected and carried out. At this time, which treatment method to adopt depends on the type of base material (whether surface hardening treatment is possible or not), the type of coating layer to be formed later (the coating layer is tightly adhered to the cured layer, etc.) and whether the resulting cured layer will be hard and have a coefficient of thermal expansion intermediate between those of the base material and the coating layer. You can decide by taking these things into consideration. In particular, in the case of nitriding, the hardness of the hardened layer obtained is somewhat lower than that of carburizing and boriding, but the temperature during treatment is 500 to 600°C (approximately 900°C in case of carburizing, It is preferable because it is low (approximately 1000°C) and has high energy efficiency during processing. The thickness of the hardened layer is usually from the surface to
It may be about 50 to 200 μm. Note that when Fe or Fe-based alloys are used as the base material, a hard and brittle Fe _2-3 N phase (ε phase) is selectively formed on the surface of the hardened layer during nitriding. It is preferable to remove the lever phase by a method such as polishing or grinding or to reduce the volume fraction prior to forming the ceramic coating layer. A ceramic coating layer is formed on this hardened layer. The ceramic used is any one or more elements belonging to group a, group Va, or group a of the periodic table, or one or more of nitrides, carbides, and borides of Si or B. In this case, the ceramic used is nitride if the hardened layer is a nitrided layer, carbide if the hardened layer is carburized, and boride if the hardened layer is a borided layer. It is preferable. Examples of nitrides include titanium nitride (TiN), zirconium nitride (ZrN), hafnium nitride (HfN), vanadium nitride (VN), niobium nitride (NbN), tantalum nitride (TaN), and chromium nitride (CrN, _Cr2 ). N), molybdenum nitride (Mo ₂ N,
MoN), tungsten nitride (W ₂ N, WN ₂ ,
Examples of carbides include titanium carbide ( _TiC ), zirconium carbide (ZrC) _, hafnium carbide (HfC) _, and vanadium carbide ₍ VC). ), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr ₃ N ₂ , Cr ₇ C ₃ , Cr ₂₃ C ₆ ), molybdenum carbide (Mo ₂ C, MoC), tungsten carbide (W ₂ C,
WC), silicon carbide (SiC), boron carbide (B ₄ C)
Examples of borides include titanium boride (TiB ₂ ), zirconium boride (ZrB ₂ ), hafnium boride (HfB ₂ ), vanadium boride (VB ₂ ), niobium boride (NbB, Nb ₃ B _{4 )} , NbB ₂ ), tantalum boride (Ta ₂ B, TaB, Ta ₃ B ₄ ), chromium boride (Cr ₃ B ₂ , CrB), molybdenum boride (Mo ₂ B,
MoB, Mo ₂ B ₅ ), tungsten boride (W ₂ B,
WB, W ₂ B ₅ ). Of these ceramics, a coating layer can be formed relatively easily. Nitride or carbide is preferable from the viewpoint of easy availability. Particularly preferred are TiN, TiC, and SiC. These coating layers are formed by applying plasma chemical vapor deposition (PCVD). In the PCVD method, the base material is used as a cathode and metal halide vapor gas is used as the cathode.
Low pressure of N ₂ or N ₂ + H ₂ (several Torr, 400-600℃)
In this method, glow discharge is generated in an atmosphere of 100% to coat the surface of a base material. This PCVD method has advantages in that it provides a coating layer with excellent abrasion resistance, has good adhesion between the coating layer and the hardened layer, and is relatively easy to form a film. There is. The thickness of the coating layer is arbitrary, but if it is too thick, thermal stress will be generated between the coating layer and the cured layer, making it easy to peel off, so it is usually about 2 μm. [Embodiment of the invention] As iron-based alloys, SLS304, SCM1, S45C,
Select SACM1 and use Ti−3Al− as the titanium alloy.
2.5V, Ti-6Al-4V were selected, and A5083 and A5052 were selected as aluminum alloys. The shape of each sample was a round bar for the Farex test. The corner specimen was subjected to corner surface hardening treatment under the conditions described below to form a hardened layer. Hardened layer thickness: approx. 50~
200μm. Nitriding treatment: A specimen is placed in an atmosphere with a volumetric mixing ratio of N ₂ and H ₂ of 1:3 and a total gas pressure of 2 Torr.
Ion nitriding was performed at 570°C for 2 hours. Carburizing treatment: The specimen was placed in methane gas at a gas pressure of 3 Torr, and was subjected to ion carburization treatment at 950°C for 1 hour. Boring treatment: After embedding the specimen in a mixed powder of boron, ferroboron, aluminum, and ammonium chloride, the entire specimen was heat-treated at 1000° C. for 3 hours. Measure the Hv of each cured layer formed, and then
Each coating layer was formed thereon by applying the PCVD method under the conditions shown in the table, and their Hv was measured. The thickness of each coating layer was 2 μm. For comparison, parts were manufactured in which each coating layer was formed directly on the surface of the base material under the same manufacturing conditions without subjecting the surface of the base material to surface hardening treatment. The wear resistance of each of the obtained parts was examined and evaluated using a Farex tester. Regarding the adhesion between the cured layer and the coating layer, we repeated a thermal cycle operation of heating the part to 200 to 300°C and rapidly cooling it to room temperature five times, and checked whether or not the coating layer peeled off or cracked. The presence or absence of occurrence was observed and evaluated. Good adhesion is indicated by ◯, poor adhesion is indicated by ×, and the middle is indicated by △.

【table】

[Table] Furthermore, for comparison, the above-mentioned
A surface hardening treatment similar to the PCVD method was performed, and parts were manufactured in which each coating layer was formed using the PVD method (Comparative Examples 19 to 23) and the CVD method (Comparative Examples 24 and 25) under the conditions shown in the following table. Each of the obtained parts was evaluated in the same manner as described above. Among the parts obtained, Comparative Examples 19 to 23 using the PVD method had variations in quality, and Comparative Examples 24 and 25 using the CVD method had parts whose base material had softened due to heating during coating. Its wear resistance was insufficient, and it could not be used for practical purposes.

【table】

〔Effect of the invention〕

As is clear from the table, the wear-resistant parts of the present invention have superior adhesion to the base material, and at the same time have a hard hardened layer on the surface of the base material, compared to conventional products in which a ceramic coating layer is directly formed on the base material. Even if external force is applied to the thin coating layer, the coating layer will not cave in and the wear resistance of the coating layer will be effectively demonstrated, which not only extends its service life but also increases reliability during use. It is also useful because of its increased functionality.

Claims (1)

[Claims] 1. A base material made of iron or an iron-based alloy, titanium or a titanium-based alloy, or aluminum or an aluminum-based alloy, and a surface of the base material subjected to any of nitriding, carburizing, or boriding. A hardened layer formed by performing the above surface hardening treatment, and a group a, group a, a of the periodic table formed on the surface of the hardened layer.
A wear-resistant part comprising a coating layer consisting of a layer or a composite layer of a nitride, carbide or boride of any element belonging to the Group 1, silicon or boron, the coating layer being formed by plasma chemical vapor deposition. A wear-resistant part characterized by being formed by a method (PCVD method). 2. The wear-resistant component according to claim 1, wherein the base material is stainless steel, the hardened layer is a layer containing iron nitride as a main component, and the coating layer is a titanium nitride layer.