JPS6137230B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a sliding member, and more specifically, a mirror surface layer of silicon carbide is deposited on a substrate made of alumina at a high deposition rate by a magnetron sputtering method. The present invention relates to a method of manufacturing a sliding member.

Conventional technology and its problems Conventionally, in order to utilize the excellent properties of silicon carbide as a sliding member used in sliding mechanisms such as mechanical seals, bearings, and turbine/pump parts, silicon carbide was deposited on a carbon substrate. Some have a film formed on them. However, the carbon base of this sliding member has inferior mechanical properties (particularly Young's modulus) compared to the silicon carbide coating, so there are problems such as distortion of the base under harsh usage conditions. There is a point. Therefore, this sliding member has limitations in terms of usage conditions, applications, etc., and the excellent properties of the silicon carbide film have not been fully exhibited.

Means for Solving the Problems As a result of various studies in view of the problems of the prior art as described above, the present inventor has discovered that silicon carbide can be deposited on a substrate made of alumina by magnetron sputtering under specific conditions. It has been found that when a mirror-like surface layer is formed, a sliding member that can substantially eliminate the problems of the prior art can be obtained. That is, the present invention provides the following method: In a vacuum chamber, an electric field is created by applying high frequency power through a cathode silicon target, and a magnetic field is created by placing a permanent magnet near the cathode silicon target. A substrate made of alumina is heated to 500 to 1000°C in the presence of a reactive gas by forming an orthogonal electromagnetic field in which the electric field and magnetic field act orthogonally to each other. A method for manufacturing a sliding member, comprising forming a mirror layer made of silicon carbide thereon at a deposition rate of 3 to 6 μ/hr.

In general, a substrate that fully exhibits the excellent properties of the silicon carbide coating layer as the sliding contact surface of a sliding member has excellent mechanical properties (especially Young's modulus) and does not cause distortion even under high loads. The material must also have a relatively small difference in coefficient of thermal expansion from silicon carbide. As a result of repeated tests on various materials, the inventor found that Al ₂ O ₃ , Fe ₂ O ₃ , MgO, ZnO, ZrO ₂ ,
It has been found that metal oxides such as ThO ₂ meet the above requirements relatively well. Subsequent research revealed that among these metal oxides, alumina (Al ₂ O ₃ ) was found to be optimal as a substrate.

The method for forming the coating layer on the substrate is as follows:
Although various methods exist, the present invention requires a magnetron sputtering method carried out under specific conditions. In other words, in the chemical vapor deposition method, it is necessary to heat the substrate to 1500°C or higher by high-frequency induction heating, which is difficult to use when using non-conductive alumina as the substrate. As a method of forming a silicon carbide film on a carbon substrate by the ion plating method, for example, there is a method described in JP-A-52-90508, but this method also applies when non-conductive alumina is used as the substrate. difficult to use.

According to the research conducted by the present inventors, it has been found that it is indeed possible to form a double coating of silicon carbide on an alumina substrate using the sputtering method, which is one of the physical vapor deposition methods. However, the biggest drawback of the conventional sputtering method is that the deposition rate is slow, and when forming a coating layer made of silicon carbide on an alumina substrate, the deposition rate is 0.3 μm/
It's only about hr. Therefore, this method is not suitable as a method for forming on an industrial scale a silicon carbide coating layer having a thickness that can be put to practical use as a sliding member. However, according to the magnetron sputtering method adopted in the present invention, an electric field is created by applying high frequency power using a cathode silicon target, and a magnetic field is created by placing a permanent magnet near the cathode silicon target, and these electric fields and When an orthogonal electron magnetic field that acts orthogonally to the magnetic field is formed, the deposition rate of silicon carbide on the alumina substrate is more than 10 times that of the normal sputtering method, making it possible to economically mass produce sliding parts. It became possible.

Hereinafter, the method of the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a sealing ring of a mechanical seal as an example of a sliding member obtained by the method of the present invention.
A base body 2 made of alumina of the sliding member 1 is coated firmly and densely with a surface layer 3 made of silicon carbide by the magnetron sputtering method described later. The surface of this surface layer 3 (the upper surface in FIG. 1) becomes a sliding surface 4 that slides on other mechanical parts and the like. This sliding surface 4 is a very flat and mirror-like surface. The sliding surface 4, which is a mirror surface, is formed by coating the base 2 with the surface layer 3 by the magnetron sputtering method, and then applying only the magnetron sputtering method without performing any finishing processing such as polishing or lapping. It was confirmed that the surface layer 3 having a mirror-like surface can be automatically formed on the substrate 2 by coating the surface layer 3 thereon. An example of an apparatus that can suitably manufacture such a sliding member 1 is shown in FIG.

In the figure, 2 is a base made of alumina, 5 is a vacuum chamber, 6 is an inert gas exhaust port, 7 is a silicon target, 8 is a permanent magnet, 9 is a heater, 10 is a shutter, 11 is an inert gas inlet, 12 is a hydrocarbon gas inlet, 13 and 13' are matching boxes, 14 and 14' are high frequency power supplies, 15 is an activation electrode, and 16 is a cooling pipe. This device is called a magnetron sputter device in terms of form, and by arranging a permanent magnet 8 near the silicon target, an orthogonal electromagnetic field is formed in the vacuum chamber 5, so that the The deposition rate of the silicon carbide surface layer can be on the order of 3 to 6 μm/hr, which is ten to several tens of times the conventional rate. That is, the illustrated device has a necessary thickness of the surface layer 3 made of silicon carbide, which is 10 to 50 μm, derived from the relationship with the durability life due to wear when the sliding member 1 is used for industrial purposes. Thickness can be formed in a short time, making it extremely useful for practical production. To explain the operation of this device, first, the base 2 is placed on the heater 9. It is also possible to obtain a plurality of sliding members at once by placing a plurality of base bodies 2 on the heater 9. Next, the inside of vacuum chamber 5 is 10 ^-6 TORR
Exhaust to order and heat heater 9 to 500℃~1000℃
Hold at low temperature (compared to CVD) of °C. Then, a hydrocarbon gas (e.g., C ₂ H ₂ ) is introduced as a reactive gas through the inlet 12 to an order of 10 ^-5 TORR to ^{10 -4} TORR, and then an inert gas (e.g., Ar) is introduced through the inlet 11 . After introduction, vapor deposition was performed using the magnetron sputtering method for 200 minutes on the order of 10 ^-3 TORR. In this way, for example, the sliding member 1 shown in FIG. 1 can be manufactured.

Effects of the Invention The sliding member obtained by the method of the present invention has excellent adhesion between the base and the surface layer, and the surface layer of silicon carbide is strong and dense, while the base has mechanical strength. Since alumina has excellent properties such as, the synergistic effect of the properties of both the base material and the surface layer makes it possible to exhibit sufficient material mechanical properties. Therefore, according to the present invention, it is possible to manufacture a sliding member that is excellent in that it takes advantage of the wear resistance and low coefficient of friction of the surface layer, and also has the characteristics of the base material that do not cause distortion. When this sliding member is used as a sealing ring of a mechanical seal, a sliding surface of a bearing, a part of a sliding part of a turbine pump, etc., its excellent effects are exhibited.

In addition, in the method of the present invention, the cathode target is
By changing to Ti, Ta, B, etc., a coating surface layer consisting of TiC, TaC, BaC, etc. can be obtained, while the reactive gas can be changed to
By changing to NH ₃ , N _{2 ,} etc., a coated surface layer consisting of Si ₃ N ₄ , TiN, BN, etc. can be obtained.

Examples Examples are shown below to further clarify the features of the present invention.

Example 1 A surface layer made of silicon carbide was formed on a base made of alumina and having an outer diameter of 30 mm, an inner diameter of 20 mm, and a thickness of 8 mm. The operating conditions were: high frequency power: 500W, acetylene (C ₂ H ₂ ) partial pressure: 2×10 ^-4 TORR, sputtering pressure: 2×10 ^-3 TORR, alumina substrate temperature: 60°C,
Retention time: 200 minutes. The thickness of the surface layer of silicon carbide formed was 10.8 μm. The surface layer is
It has a mirror-like surface, and its Bitkers hardness is
It was 3000Kg/ ^mm2 . In addition, the surface layer made of silicon carbide was firmly adhered to the substrate although it was directly deposited on the substrate made of alumina.

After subjecting the thus obtained sliding member to a 100-hour dry wear test using a Suzuki type wear tester, 1/1
The amount of wear was measured using a surface measuring device capable of measuring up to 1,000 mm, and the amount of wear was zero.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of a sliding member according to the present invention, and FIG. 2 is a schematic sectional view of a sputtering apparatus for manufacturing the sliding member of FIG. 1. DESCRIPTION OF SYMBOLS 1...Sliding member, 2...Substrate, 3...Surface layer, 4...Sliding surface, 5...Vacuum chamber, 8...Permanent magnet.

Claims (1)

[Claims] 1. In a vacuum chamber, an electric field is created by applying high frequency power using a cathode silicon target, and a magnetic field is created by placing a permanent magnet near the cathode silicon target, and these electric fields and magnetic fields act orthogonally to each other. An orthogonal electromagnetic field is formed and the cathodic silicon target is bombarded with an inert gas to deposit silicon carbide on a substrate made of alumina heated to 500-1000°C in the presence of a reactive gas at a deposition rate of 3-6 μm/hr. A method for manufacturing a sliding member, comprising forming a mirror layer.