JP2013091823A - Sliding component - Google Patents

Abstract

[PROBLEMS] To provide a wear resistance superior to that of a conventional amorphous carbon film and having a low frictional property equivalent to that of a conventional amorphous carbon film such as DLC when used in a non-lubricated or boundary lubricated environment. Provided is a sliding part on which a film having
A sliding component according to the present invention is a sliding component used in a non-lubricated or boundary lubrication environment, and an amorphous hard film is formed on a sliding surface of a base material constituting the sliding component. A formed sliding part, wherein the amorphous hard film contains at least boron, carbon, nitrogen and oxygen, and the total of the boron, carbon, nitrogen and oxygen is 100 atomic% In addition, the carbon content is 12 atomic% or more, the nitrogen content is 10 atomic% or more, the boron content is higher than each of the carbon and nitrogen, and the oxygen The content of is not less than 5 atom% and not more than 12 atom%, and the thickness of the amorphous hard film is not less than 0.08 μm and not more than 10 μm.
[Selection] Figure 1

Description

  The present invention relates to a sliding component used in a non-lubricated or boundary lubrication environment, and more particularly to a sliding component in which an amorphous hard film is formed on a sliding surface.

  With the main purpose of reducing friction at sliding parts such as automobile parts, sliding parts with a hard coating formed on the sliding surface have been intensively researched and developed. Hard coatings include thin-film amorphous carbon materials called aC (amorphous carbon), aC: H (hydrogenated amorphous carbon), iC (eye carbon), DLC (diamond-like carbon), and hard carbon. Often used.

Amorphous carbon film is a structure that contains both sp ² and sp ³ bonds as bonds between carbon atoms, has no clear crystal structure (no grain boundaries), and has high hardness and high toughness. It has the features of having both low friction and low friction. Therefore, the amorphous carbon film has high fracture toughness and excellent friction reduction effect compared to crystalline hard films such as TiN (titanium nitride), TiAlN (titanium aluminum nitride) and CrN (chromium nitride). Has been.

  On the other hand, amorphous carbon film is known to change into a microstructure that is more thermodynamically more stable but mechanically brittle in high temperature environments (eg, about 350 ° C. or higher). (About 500 ° C) and the heat resistance temperature of TiAlN (about 800 ° C) are extremely low, and there is a problem that the wear resistance in a high temperature environment is low. In addition, when the amorphous carbon film is used in an environment where lubricating oil coexists, there is a problem that the expected low friction cannot be obtained sufficiently.

  In order to solve such a problem, various coatings with different amorphous carbon compositions have been studied. For example, Patent Document 1 contains boron (B) and nitrogen (N) in a rolling device in which one of the first member and the second member moves relative to the other when the rolling element rolls. A rolling device in which a BCN layer made of a diamond-like carbon film is formed on a rolling surface is disclosed. The boron and nitrogen contents in the B—C—N layer are preferably boron: 40 atomic% or less, nitrogen: 58 atomic% or less, and the total of boron and nitrogen: 80 atomic% or less in the entire B—C—N layer. According to Patent Document 1, seizure resistance (lubricity) and wear resistance are higher than when a DLC film not containing boron and nitrogen is formed.

  In Patent Document 2, in order to reduce the frictional resistance of the fastening sliding surface of the fastening jig member, a hard coating of boron carbonitride in which a part of carbon is replaced with boron and nitrogen is applied to the whole or part of the fastening sliding surface. A fastening jig member coated on is disclosed. As a hard coating, a boron carbonitride coating (based on a coating composed of carbon of 40 atomic% or more and less than 99 atomic% and hydrogen of 1 atomic% or more and less than 40 atomic%, with a portion of the carbon replaced with boron and nitrogen ( The total substitution amount is said to be 10 to 80%).

  Patent Document 3 discloses a low-friction sliding member that is used in a wet condition using a lubricating oil containing molybdenum and includes a base material and an amorphous hard carbon film that is formed on the surface of the base material and that is in sliding contact with a counterpart material. The amorphous hard carbon film is mainly composed of carbon (C), and the total amount of the amorphous carbon film is 100 atomic%, and hydrogen (H) is 5 atomic% or more and 25 atomic% or less. A low friction sliding member containing a predetermined amount of boron (B), magnesium (Mg), titanium (Ti) or manganese (Mn) is disclosed. According to Patent Document 3, friction is greatly reduced under wet conditions using a lubricating oil containing molybdenum.

  Patent Document 4 discloses a hard carbon film sliding member in which at least a surface layer is made of a hard carbon film and nitrogen and / or oxygen is contained on the surface of the hard carbon film in a sliding member used in lubricating oil. Has been. The hard carbon film preferably has a surface hydrogen content of 10 atomic% or less and a surface nitrogen and / or oxygen content of 0.5 atomic% or more and 30 atomic% or less. According to Patent Document 4, since the solid lubricity of the hard carbon film can be effectively functioned even in lubricating oil, a long-life hard carbon film sliding member having excellent lubricity and wear resistance is provided. It is supposed to be possible.

  Patent Document 5 discloses a sliding member comprising a base material having a sliding surface that is slid in the presence of lubricating oil, and a coating fixed to at least a part of the sliding surface, Discloses a sliding member made of diamond-like carbon containing carbon as a main component and containing 1 to 5 atomic% of silicon and 20 to 40 atomic% of hydrogen. The coating contains at least one of less than 1 atomic percent nitrogen and less than 5 atomic percent oxygen. According to Patent Document 5, the sliding member is said to exhibit excellent wear resistance and high seizure resistance under a high surface pressure or high speed sliding environment in lubricating oil.

JP 2004-60668 A JP 2005-282668 A JP 2011-32429 A JP 2000-297373 A JP 2003-336542 A

E. H. A. Dekempeneer et al., “Tribological properties of r. F. PACVD amorphous B-N-C coatings”, Thin Solid Films, 281-282 (1996) pp. 331-333.

  As described above, the conventional film with a changed composition of amorphous carbon is said to exhibit low friction properties or improve wear resistance even when used in an environment where lubricating oil coexists. . However, in non-lubricating or boundary lubrication (lubrication where the lubricant is not sufficient), a conventional film with a different composition of amorphous carbon has a coefficient of friction than a normal amorphous carbon film (for example, DLC). There is a weak point that it becomes higher (for example, see Non-Patent Document 1). On the other hand, as described above, the amorphous carbon film such as DLC has the advantage of low friction, but it is weakened by frictional heat in an environment where large frictional heat is generated, and thus has low wear resistance. It also has a weak point.

  Therefore, the object of the present invention is to have a low frictional property equivalent to that of a conventional amorphous carbon film such as DLC when used in a non-lubricated or boundary lubricated environment, and more than a conventional amorphous carbon film. An object of the present invention is to provide a sliding component on which a film having excellent wear resistance is formed.

  One aspect of the present invention is a sliding component that is used in a non-lubricated or boundary lubrication environment in order to achieve the above-described object, and an amorphous hard material is formed on a sliding surface of a base material constituting the sliding component. A sliding part having a film formed thereon, wherein the amorphous hard film contains at least boron, carbon, nitrogen, and oxygen, and a total of the boron, the carbon, the nitrogen, and the oxygen is 100 atomic%. When the carbon content is 12 atomic% or more, the nitrogen content is 10 atomic% or more, the boron content is higher than each of the carbon and nitrogen, Provided is a sliding component characterized in that the oxygen content is 5 atomic% or more and 12 atomic% or less, and the thickness of the amorphous hard film is 0.08 μm or more and 10 μm or less.

  In the present invention, the content is defined as the average content in the film (not the local content). Further, in the present invention, the non-lubricated or boundary lubrication environment includes a case where the state is temporarily non-lubricated or boundary lubricated (for example, at a cold start).

Moreover, the present invention can add the following improvements and changes to the sliding component according to the above invention.
(I) The amorphous hard film contains a part of the boron and contains silicon instead of the boron. In other words, the amorphous hard film contains at least boron, silicon, carbon, nitrogen and oxygen, and when the total of the boron, silicon, carbon, nitrogen and oxygen is 100 atomic%, The carbon content is 12 atomic% or more, the nitrogen content is 10 atomic% or more, and the total content of the boron and the silicon is higher than the content of each of the carbon and nitrogen. The oxygen content is 5 atom% or more and 12 atom% or less, and the thickness of the amorphous hard film is 0.08 μm or more and 10 μm or less.
(Ii) The amorphous hard film has a fine structure in which crystal particles having a diameter of 10 nm or less are dispersed in an amorphous matrix.
(Iii) The amorphous hard film further contains 10 atomic parts or less of hydrogen and 8 atomic parts or less of argon when the total of the boron, the carbon, the nitrogen, and the oxygen is 100 atomic parts. . Note that when part of the boron contains silicon instead of the boron, the total of the boron, the silicon, the carbon, the nitrogen, and the oxygen is 100 atomic parts.
(Iv) In the sliding component, a plurality of intermediate layers are interposed between the amorphous hard film and the base material, and the plurality of intermediate layers are formed directly on the base material, and silicon, chromium, A first intermediate layer made of one or more elements selected from titanium and tungsten, and an element of the first intermediate layer formed on the first intermediate layer and an element constituting the amorphous hard film. A second intermediate layer, wherein the element content of the first intermediate layer gradually decreases and the element content of the amorphous hard film gradually increases.
(V) The sliding component includes a valve lifter, an adjusting shim, a cam, a camshaft, a rocker arm, a tappet, a piston, a piston pin, a piston ring, a timing gear, a timing chain, and a fuel supply system disposed in the internal combustion engine. One of an injector, a plunger, a cylinder, a cam, and a vane disposed inside.
(Vi) In the manufacturing method of the sliding component, the formation of the amorphous hard film is performed on the sliding surface of the substrate by a reactive sputtering method using a non-equilibrium magnetron sputtering apparatus, A boron carbide target is used at least as a supply source of the boron component and the carbon component, and a mixed gas containing at least nitrogen and oxygen is used as a supply source of the nitrogen component and the oxygen component.

  According to the present invention, when used in a non-lubricated or boundary lubrication environment, it has low friction equivalent to conventional amorphous carbon films such as DLC and is superior to conventional amorphous carbon films. It is possible to provide a sliding component on which a film having wear resistance is formed.

It is a cross-sectional schematic diagram of one example of the sliding component according to the present invention and an image diagram of the composition distribution in the cross-section. It is a cross-sectional schematic diagram which shows the outline of the friction abrasion test in a lubrication environment. It is a perspective schematic diagram which shows the outline of the friction abrasion test in a non-lubricated environment.

(Basic idea of the hard coating of the present invention)
The hard coating formed on the sliding surface of the sliding component according to the present invention is based on an amorphous carbon boron nitride coating and contains a controlled amount of oxygen. Amorphous carbon boron nitride is characterized in that the bond between boron, nitrogen and carbon takes the same form as the bond between carbons in amorphous carbon, and it contains both sp ² and sp ³ bonds. Form a structure.

As described above, when amorphous carbon is subjected to thermal energy (for example, frictional heat), a part of sp ³ bond between carbons is changed to sp ² bond and a graphite structure (a layer composed of sp ² bonds). Structure) is locally formed and has a low friction mechanism by self-lubricating (solid lubrication). In other words, this means that the structure is thermally unstable and was also a factor of poor wear resistance.

On the other hand, amorphous carbon nitride boron has excellent thermal stability of the bond between boron and nitrogen, so the sp ³ bond does not easily change to the sp ² bond, and the same high level as amorphous carbon. In addition to hardness and high toughness, it is possible to exhibit heat resistance and high wear resistance. However, with respect to low friction, although it is superior to other nitrides, there is a weakness that cannot be said to be lower than that of amorphous carbon.

Therefore, in the present invention, the controlled amount of oxygen is intentionally contained in amorphous carbon nitride boron. The contained oxygen is mainly bonded to boron in the carbon nitride boron. Thereby, a bond between boron and oxygen (BO bond) is partially formed in the amorphous carbon nitride boride film. Boron oxide composed of oxygen and boron can exhibit a low friction property according to a self-lubricating mechanism by forming a layered structure. Note that the composition of boron oxide in the hard coating is not limited to B ₂ O ₃ which is stable at room temperature, and may take the composition range of B _{1 to 2} O _{3 due to} the laminated structure of BO ₃ it can.

  Hereinafter, embodiments according to the present invention will be described more specifically. However, the present invention is not limited to the embodiments taken up here, and can be appropriately combined and improved without departing from the scope of the invention.

(Structure of hard coating)
As described above, the hard film formed on the sliding surface of the sliding component according to the present invention contains at least boron, carbon, nitrogen and oxygen as its components. When the total of boron, carbon, nitrogen and oxygen is 100 atomic%, the carbon content is 12 atomic% or more, the nitrogen content is 10 atomic% or more, and the boron content is carbon and nitrogen. The oxygen content is 5 atomic% or more and 12 atomic% or less.

  When the carbon content is less than 12 atomic%, it becomes difficult to maintain a stable amorphous structure. When the nitrogen content is less than 10 atomic%, the number of bonds that contribute to heat resistance (B—N bond, C—N bond, and C═N bond) decreases, and heat resistance decreases. When the boron content is lower than the carbon content or the nitrogen content, heat resistance and wear resistance are reduced.

  The greatest point of the present invention resides in intentionally containing a controlled amount of oxygen in amorphous carbon nitride boron. When the oxygen content is less than 5 atomic%, the boron oxide structure (B—O bond) is insufficient and sufficient low friction cannot be obtained. On the other hand, when the oxygen content exceeds 12 atomic%, a brittle atomic bond (fragile structure) is formed in the amorphous film, and the film hardness and wear resistance are lowered.

  The thickness of the amorphous hard film of the present invention is preferably 0.08 μm or more and 10 μm or less. A thickness of 0.08 μm or more is necessary to ensure practically sufficient durability (durability that the ground is not exposed due to wear). On the other hand, if the thickness exceeds 10 μm, it tends to peel off, which is not preferable.

  The amorphous hard coating of the present invention is preferably contained so that a part of the boron component is replaced with a group IV element. As the group IV element to be contained, at least one of Si, Ge, and Sn can be used. In particular, silicon having an atomic radius close to that of carbon is preferably contained. Thereby, high hardness can be improved.

  The hard coating of the present invention is mainly composed of an amorphous structure, but fine crystal particles (for example, boron oxide crystal particles and silicon oxide crystal particles) having a diameter of 10 nm or less are dispersed in an amorphous matrix. May be. However, if the size of the dispersed crystal particles exceeds 10 nm, the high toughness inherent to the amorphous hard coating is impaired and the fracture strength is lowered. Therefore, fine crystal particles having a diameter of 10 nm or less are desirable.

  For the analysis of hard coating composition and microstructure, Raman spectroscopy, transmission electron microscope (TEM), Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), electron beam A diffraction method (LEED / RHEED), an X-ray photoelectron spectroscopy (XPS), a nuclear magnetic resonance method (NMR), etc. can be used. Among these, the composition distribution in the thickness direction of the film and the structure of the fine crystal particles are determined by the high-resolution transmission electron microscope (TEM-EDX) or Auger electron with an energy dispersive X-ray spectrometer in the cross-sectional observation of the specimen. It can analyze suitably by spectroscopy (AES).

  In the hard coating of the present invention, hydrogen or argon may be mixed as an inevitable element in its production (a production method will be described later). In that case, when the total of boron, carbon, nitrogen and oxygen is 100 atomic parts, it is preferable to control hydrogen to 10 atomic parts or less and argon to 8 atomic parts or less. Exceeding the specified range is not preferable because the film becomes brittle. When silicon is contained in the film, the total of boron, silicon, carbon, nitrogen and oxygen is regarded as 100 atomic parts.

(Base material)
In the present invention, the base material on which the amorphous hard film is formed is not particularly limited. However, considering durability and the like, for example, steel materials, aluminum materials, engineering plastics, and ceramics can be suitably used. In addition, when using a steel material as the base material, it is preferable to use a hard steel material in order to improve the film adhesion, but the surface of the soft steel material is hardened by performing a surface treatment such as nitriding, carburizing, carbonitriding, etc. It may be a In addition, if the surface roughness of the base material is larger than 1/10 of the film thickness to be formed, the low friction effect cannot be sufficiently exhibited, so the base material surface is finished in advance (for example, the average surface roughness Ra is 0.1 μm) The following is desirable.

(Middle layer)
FIG. 1 is a schematic cross-sectional view of an example of a sliding component according to the present invention and an image diagram of a composition distribution in the cross-section. As shown in FIG. 1, the sliding component 1 according to the present invention has an amorphous hard coating 3 formed on the sliding surface of a substrate 2. The amorphous hard coating 3 may be formed directly on the substrate 2, but it is more preferable to have a structure in which the intermediate layer 4 is provided in order to improve the adhesion with the substrate 2.

  As the intermediate layer 4, a first intermediate layer 41 made of only metal is formed immediately above the base material 2, and the elements of the first intermediate layer 41 and the amorphous hard film 3 are formed immediately above the first intermediate layer 41. A second intermediate layer 42 composed of elements is formed, and the composition profile in the thickness direction of the second intermediate layer 42 continuously changes from the interface with the first intermediate layer 41 to the interface with the amorphous hard coating 3. It is desirable that In other words, in the second intermediate layer 42, the elemental content of the first intermediate layer 41 gradually decreases and the elemental content of the amorphous hard film 3 gradually increases. It has a composition close to 3. By forming such a multilayer structure, the internal stress of the amorphous hard coating 3 is relaxed and the adhesion with the base material 2 is improved, and interfacial peeling is suppressed and durability can be further improved. it can. The metal element used for the first intermediate layer 41 is preferably at least one of silicon (Si), chromium (Cr), titanium (Ti), and tungsten (W).

(Sliding parts)
The sliding component according to the present invention is suitable for a component that is used in a non-lubricated or boundary lubricated environment (including a case where the lubricant is temporarily non-lubricated or boundary lubricated (for example, during a cold start)). For example, examples of the sliding parts disposed in the internal combustion engine include a valve lifter, an adjusting shim, a cam, a camshaft, a rocker arm, a tappet, a piston, a piston pin, a piston ring, a timing gear, and a timing chain. In addition, examples of the sliding parts arranged in the fuel supply system include an injector, a plunger, a cylinder, a cam, and a vane. However, the present invention is not limited to these, and can be widely applied to other sliding parts.

(Production method)
The amorphous hard film of the present invention is a material having a high melting point, and there is a concern about an adverse effect on the substrate when it is formed on the substrate by using a normal heat treatment (for example, an electric furnace). Therefore, a manufacturing method using plasma that can realize high energy at a low temperature is preferable.

  As a method for forming the amorphous hard film of the present invention, an existing method such as a sputtering method, a plasma CVD method, or an ion plating method can be used, but it is particularly desirable to use a reactive sputtering method. The reactive sputtering method is a film forming method that can produce a smooth coating surface and easily produce an amorphous boron nitride carbon coating in which boron, carbon, and nitrogen are bonded. Further, a harder film can be produced by performing reactive sputtering using nitrogen gas, ammonia gas, oxygen gas, or air as a supply source of nitrogen and oxygen.

  In carrying out the reactive sputtering method, it is preferable to use a manufacturing apparatus incorporating a non-equilibrium magnetron sputtering (UBMS) technique and / or a high power pulse sputtering (HPPMS) technique. When using a conventional sputtering system, the energy of the plasma is limited and the plasma is mainly excited in the vicinity of the target, so it is difficult to maintain a high excitation state in the vicinity of the substrate that is the film forming material. is there.

  On the other hand, the non-equilibrium magnetron sputtering technique is a technique that can increase the plasma density on the substrate side by controlling the plasma distribution. Further, the high-power pulse sputtering technique is a technique that can improve the plasma generation efficiency on the target. When reactive sputtering is performed with an apparatus using these techniques, a harder film can be formed by improving the plasma density.

  When producing the carbon nitride boron coating (BCNO coating) of the present invention, a boron component or a combination of a boron carbide target and a graphite target is used as a carbon component and boron component supply source, and a nitrogen component and an oxygen component are supplied. It is desirable to use a mixed gas containing at least nitrogen and oxygen (for example, a combination of nitrogen gas, oxygen gas, and argon gas, or a combination of nitrogen gas, ammonia gas, air, and argon gas) as a source. For the purpose of enhancing the reduction reaction, hydrogen gas or hydrocarbon gas may be used in combination, but it is preferable to reduce hydrogen remaining in the amorphous hard film as much as possible.

  Further, when the boron nitride silicon carbide film (SiBCNO film) of the present invention containing a silicon component instead of the boron component of BCNO is produced, in addition to the BCNO film production method described above, as a silicon component supply source It is preferable to use a silicon target or a silicon carbide target. A gas such as silane gas or tetramethylsilane gas may be used as a supply source of the silicon component, but it is preferable to control so that the amount of hydrogen remaining in the amorphous hard film is as small as possible.

  Hereinafter, specific examples of the present invention will be described in detail by way of examples. In addition, this invention is not limited to a following example.

(Production of Example 1)
In a non-equilibrium magnetron sputtering apparatus, a base material (surface-polished carburized and hardened steel), a chromium target, and a boron carbide target were set. A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the chromium target while flowing argon gas. Subsequently, electric power was additionally supplied to the boron carbide target, and nitrogen gas and oxygen gas were additionally introduced to form a second intermediate layer (thickness 0.5 μm). In the formation of the second intermediate layer, the target power and the gas flow rate were adjusted so that the chromium concentration gradually decreased and the carbon concentration and boron concentration gradually increased. Thereafter, the power of the chromium target was cut off, and the argon carbide, nitrogen gas, and oxygen gas were continuously flowed in, and the power was continuously supplied to the boron carbide target to form the amorphous BCNO film (thickness 1.7 μm) of Example 1. A film was formed.

  When the average surface roughness Ra of the obtained BCNO film was measured, it was 0.02 μm, which was the same as that of the base material. Ion milling was performed on the cross section of the test piece, and the composition analysis of the BCNO film was performed by AES. The AES probe diameter was 25 nm, and measurements were taken at 27 nm intervals. As a result, the average atomic concentration ratio was “B: C: N: O = 49.5: 14.5: 27.5: 8.5”, confirming that the desired composition was obtained. It was confirmed that the contents of the H component and Ar component were 10 atomic parts or less and 8 atomic parts or less, respectively, when the total of B, C, N, and O was 100 atomic parts. It was also confirmed that the composition distribution was almost uniform in the thickness direction of the BCNO film. When the film hardness of the BCNO film was measured with a micro indentation hardness tester (Elionix, Inc., ENT-110a), it was 15 GPa. Table 1 shows the properties of the film.

(Production of Examples 2 to 6 and Comparative Examples 1 to 7)
Using a non-equilibrium magnetron sputtering apparatus, a griffet target was added, and Examples 2 to 5 and Comparative Examples 1 to 7 were produced by the same procedure as Example 1. At this time, an amorphous BCNO film having a different composition and film thickness was formed by adjusting the target input power, gas flow rate, and film formation time. The properties of the obtained BCNO film were examined in the same manner as in Example 1. Table 1 shows the properties of each film.

(Production of Example 7)
A base material (surface-polished carburized and hardened steel), a chromium target, and a boron carbide target were set in a high-power pulse sputtering apparatus (Hauser Techno Coating BV). A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the chromium target while flowing argon gas. Thereafter, the power of the chromium target was shut off, and power was supplied to the boron carbide target while flowing argon gas, nitrogen gas, and oxygen gas, and the oxygen concentration was the amorphous BCNO coating of Example 7 (thickness 1.7 μm). Was deposited. A second intermediate layer was not formed. The properties of the obtained BCNO film were examined in the same manner as in Example 1. Table 1 shows properties of Example 7.

(Production of Example 8)
In a non-equilibrium magnetron sputtering apparatus, a base material (surface-polished carburized and hardened steel), a silicon target, a griffite target, and a boron carbide target were set. A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the silicon target while flowing argon gas. Subsequently, the second intermediate layer (thickness 0.5 μm) was formed by additionally supplying electric power to the griffite target and the boron carbide target, and additionally flowing in nitrogen gas and oxygen gas. In the formation of the second intermediate layer, the target power and the gas flow rate were adjusted so that the silicon concentration gradually decreased and the carbon concentration and boron concentration gradually increased. Thereafter, while continuously flowing argon gas, nitrogen gas and oxygen gas, power was continuously supplied to the silicon target, the lyphite target, and the boron carbide target, and the amorphous SiBCNO film of Example 8 (thickness 1.9 μm) was formed. A film was formed. The properties of the obtained SiBCNO film were examined in the same manner as in Example 1. The properties of Example 8 are shown in Table 1.

(Production of Examples 9 to 10 and Comparative Examples 8 to 12)
Using a non-equilibrium magnetron sputtering apparatus, Examples 9 to 10 and Comparative Examples 8 to 12 were produced by the same procedure as Example 8. At this time, an amorphous SiBCNO film having a different composition and film thickness was formed by adjusting the target input power, gas flow rate, and film formation time. The properties of the obtained SiBCNO film were examined in the same manner as in Example 1. Table 1 shows the properties of each film.

(Production of Example 11)
A base material (surface-polished carburized and hardened steel), a silicon target, and a composite target of silicon and boron carbide were set in a high-power pulse sputtering apparatus (Hauser Techno Coating BV). A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the silicon target while flowing argon gas. Thereafter, the power of the silicon target was cut off, and power was supplied to the composite target while flowing argon gas, nitrogen gas, and oxygen gas into the amorphous SiBCNO film (thickness: 1.9 μm) of Example 11. . A second intermediate layer was not formed. The properties of the obtained SiBCNO film were examined in the same manner as in Example 1. Table 1 shows the properties of Example 11.

(Production of Example 12)
Example 12 was produced in the same procedure as in Example 11 using a high-power pulse sputtering apparatus. At this time, an amorphous SiBCNO film having a different composition and film thickness was formed by adjusting the target input power, gas flow rate, and film formation time. The properties of the obtained SiBCNO film were examined in the same manner as in Example 1. Table 1 shows the properties of Example 12.

(Production of Comparative Example 13)
In a non-equilibrium magnetron sputtering apparatus, a substrate (carburized and hardened steel with surface polishing), a chromium target, and a griffite target were set. A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the chromium target while flowing argon gas. Subsequently, the second intermediate layer (thickness 0.5 μm) was formed by additionally supplying electric power to the griffet target and additionally injecting methane gas. In the formation of the second intermediate layer, the target power and the gas flow rate were adjusted so that the chromium concentration gradually decreased and the carbon concentration gradually increased. Thereafter, the power of the chromium target was cut off, and power was continuously supplied to the graphite target while continuously flowing in argon gas and methane gas to form a DLC film (thickness 1.8 μm) of Comparative Example 13. The properties of the obtained DLC film were examined in the same manner as in Example 1. The properties of Comparative Example 13 are shown in Table 1.

(Production of Comparative Example 14)
An amorphous carbon nitride film (CN) of Comparative Example 14 was formed by the same procedure as Comparative Example 13 except that nitrogen gas was additionally introduced using a non-equilibrium magnetron sputtering apparatus. The properties of the obtained CN film were examined in the same manner as in Example 1. The properties of Comparative Example 14 are shown in Table 1.

(Production of Comparative Example 15)
In a non-equilibrium magnetron sputtering apparatus, a base material (surface-polished carburized and hardened steel), a chromium target, and a boron nitride (h-BN) target were set. A first intermediate layer (thickness: 0.1 μm) was formed on the surface of the substrate by supplying power to the chromium target while flowing argon gas. Subsequently, power was additionally supplied to the boron nitride target, and methane gas and oxygen gas were additionally introduced to form a second intermediate layer (thickness 0.5 μm). In forming the second intermediate layer, the target power and the gas flow rate were adjusted so that the chromium concentration gradually decreased and the boron concentration gradually increased. Thereafter, the power of the chromium target was cut off, and power was continuously supplied to the boron nitride target while argon gas, methane gas, and oxygen gas were continuously flowed in to form a BNO film (thickness: 1.6 μm) of Comparative Example 15. The properties of the obtained BNO film were examined in the same manner as in Example 1. Properties of Comparative Example 15 are shown in Table 1.

(Production of Comparative Example 16)
Using an arc ion plating (AIP) apparatus, a titanium nitride film (TiN, thickness 2.0 μm) was formed on a substrate (carburized and hardened steel with surface polishing). The properties of the obtained TiN film were examined in the same manner as in Example 1. Table 1 shows the properties of Comparative Example 16.

(Preparation of Comparative Example 17)
The carburized and hardened steel without a hard coating was surface-polished to prepare a test piece (Comparative Example 17) having only a base material. The properties of Comparative Example 17 were examined in the same manner as in Example 1. As a result, the average surface roughness was Ra = 0.02 μm, and the carburized surface had a Rockwell hardness of 58 HRc.

(Microstructural analysis and microstructural observation)
The fine structure was analyzed using the electron diffraction pattern of a transmission electron microscope with respect to each film | membrane (Examples 1-12 and Comparative Examples 1-16) formed into a film. As a result, in the films other than Comparative Example 13, a halo pattern showing an amorphous state was observed, and it was confirmed that the film was mainly composed of an amorphous material. On the other hand, the TiN film of Comparative Example 13 showed a clear diffraction pattern in electron beam diffraction of a transmission electron microscope, and was confirmed to be a crystalline film.

  In addition, the fine structure was observed with a high-resolution functional image for each film formed. As a result, in Example 1, Example 3, Examples 4 to 6, and Examples 9 to 12, structures in which crystal particles having a diameter of 2 to 8 nm were dispersed in an amorphous matrix were confirmed. On the other hand, Comparative Examples 4 to 5 and Comparative Example 11 were confirmed to have a structure in which crystal particles having a diameter of about 20 nm were dispersed in an amorphous matrix, and Comparative Examples 6 and 12 were amorphous matrixes. A structure in which crystal grains having a diameter of 100 nm or more were dispersed in the phase was confirmed.

(Friction and wear test)
As described above, the present invention has a low frictional property equivalent to that of a conventional amorphous carbon film such as DLC when used in a boundary lubrication or non-lubricated environment, and more than a conventional amorphous carbon film. The object is to provide a sliding part on which a film having excellent wear resistance is formed. Therefore, the frictional wear acceleration test was performed using the prepared specimens having various hard coatings, and the friction coefficient and the wear rate were measured in the boundary lubrication environment and the non-lubrication environment. It can be considered that the smaller the wear rate, the higher the wear resistance. A Matsubara type friction and wear tester (Orientec Co., Ltd., model: EFM-III) was used for the friction and wear test.

FIG. 2 is a schematic cross-sectional view showing an outline of a frictional wear test under a lubrication environment. As shown in FIG. 2, the friction and wear test apparatus 10 includes a plate test piece 11, a ring test piece 12, a heater 13, a torque measurement arm 14, a load cell 15, a bathtub 16, an immersion liquid 17, and a heat retaining oil. It consists of 18. The plate test piece 11 is a steel plate (SUS440B, width 3 mm, length 20 mm) used as a base material, and various coatings are formed on the base material surface serving as a sliding surface. The ring test piece 12 was a counterpart material for sliding, and a steel pipe (SKD10, outer radius 5.5 mm, inner radius 3.5 mm) whose surface was gas-nitrided was used. The apparent contact area between the plate test piece 11 and the ring test piece 12 is 12.2 mm ² . Polyalphaolefin was used as the immersion liquid 17 to fill the bathtub 16.

In the frictional wear test, the load on the ring test piece 12 was increased from 0 kgf to 10 kgf while rotating the plate test piece 11 so that the peripheral speed of the outer periphery of the sliding part was 0.5 m / s, and the surface pressure was 8.0 MPa. For 10 hours (5.2 × 10 ⁵ rotations). Further, the temperature of the heat retaining oil 18 was measured, and the test was carried out by adjusting the heater 13 so that the test temperature was 90 ° C.

  The friction coefficient was obtained by averaging the friction coefficients measured during holding for 10 hours, and the wear rate was obtained by dividing the difference in film thickness before and after the test on the sliding surface by the holding time. For a film with a high wear rate, the wear rate was measured by adjusting the holding time so that the film thickness after the test did not become zero.

  In the surface contact sliding test, the thickness t of the lubricating oil is given by the following equation when the viscosity of the lubricating oil is η, the speed is v, the apparent contact area is a, the friction coefficient is μ, and the load is P. (1) can be approximated.

The viscosity of polyalphaolefin at an oil temperature of 100 ° C. is η = 1.60 × 10 ⁻³ Pa · s, and the viscosity of polyalphaolefin at an oil temperature of 40 ° C. is η = 5.11 × 10 ⁻³ Pa · s. is there. Substituting v = 0.5 m / s, a = 1.22 x 10 ^-5 m ² , and μ = 0.15 as a typical friction coefficient into equation (1), the oil film thickness t when the oil temperature is set to 90 ° C Is in the range of “6.6 × 10 ⁻¹⁰ m <t <2.1 × 10 ⁻⁹ m”.

Since the average surface roughness of the plate specimen 11 and the ring specimen 12 used for the frictional wear test is Ra> 10 ^-8 m, the oil film thickness t is sufficiently higher than the average surface roughness of the sliding surface. thin. That is, it can be said that the lubrication condition in this friction and wear test is “boundary lubrication” in which the lubricant present on the sliding surface has a molecular level thickness and the influence of solid contact between the test pieces cannot be ignored. The test results are shown in Table 2.

  FIG. 3 is a schematic perspective view showing an outline of a friction and wear test in a non-lubricated environment. As shown in FIG. 3, the friction and wear test apparatus 20 includes a disk test piece 21, a ball test piece 22, a torque measurement arm 14, and a load cell 15. The disk test piece 21 is obtained by using a steel board (SUS440B, diameter 20 mm) as a base material, and forming various coatings on the base material surface serving as a sliding surface. The ball test piece 22 used as a sliding counterpart material was a steel ball (SKD10, diameter 4 mm) whose surface was gas-nitrided.

  The friction and wear test is performed at room temperature (20 to 25 ° C.), the disk test piece 21 is rotated so that the peripheral speed of the sliding part is 0.5 m / s, the load on the ball test piece 22 is 10 kgf, and the surface The pressure was maintained at 1670 MPa for 10 minutes. The surface pressure was obtained as the case of “contact between spherical surface and flat surface” in Hertz contact stress.

  The friction coefficient was obtained by averaging the friction coefficients measured during holding for 10 minutes, and the wear rate was obtained by dividing the difference in film thickness before and after the test at the sliding portion by the holding time. For a film with a high wear rate, the wear rate was measured by adjusting the holding time so that the film thickness after the test did not become zero. The test results are shown in Table 2.

  As shown in Table 2, it was confirmed that Comparative Example 13 (DLC film) had a low friction coefficient but a significantly high wear rate in both boundary lubrication and non-lubricated environments. This was thought to be due to the self-lubricating (solid lubrication) mechanism of the DLC film. In Comparative Example 14 (CN film), the wear rate was reduced as compared to the DLC film (the wear resistance was improved), but the friction coefficient was increased 1.4 to 1.7 times. Comparative Example 15 (BNO film) had a low coefficient of friction of less than 1.2 times that of the DLC film, but was damaged due to film peeling during sliding. Since Comparative Example 16 (TiN film) had a very high friction coefficient and seized in an unlubricated environment, the test had to be interrupted. Comparative Example 17 (a test piece that was not coated with a film) caused seizure in both boundary lubrication and non-lubrication environments.

  On the other hand, Examples 1 to 12 (BCNO film, SiBCNO film) according to the present invention have a friction coefficient under a boundary lubrication environment of 0.100 or less and exhibit low friction equivalent to that of a DLC film. It has been confirmed that the wear rate can be reduced by one to two orders of magnitude compared to the DLC film, and the wear rate in a non-lubricated environment can be reduced by one order of magnitude or more than the DLC film.

  On the other hand, the coatings with less oxygen concentration than those defined in the present invention (Comparative Examples 1 to 3 and Comparative Examples 8 to 10) had a friction coefficient of more than 0.110 in the boundary lubrication environment. In addition, in the films having the oxygen concentration higher than the regulation of the present invention (Comparative Examples 4 to 6, Comparative Examples 11 to 12), the wear rate is increased (the wear resistance is decreased), and the film is peeled off during the test. Some samples would end up. This was thought to be because excess oxygen formed a fragile structure (fragile bond) in the film.

  Further, when Example 4 and Example 5 and Comparative Example 7 having substantially the same coating composition and different film thicknesses were compared, Example 4 showed good results even though the film thickness was very thin at 0.08 μm. Excellent wear resistance. Example 5 also showed good wear resistance. Since this friction and wear test is an accelerated test under very severe conditions, the fact that this test showed good wear resistance means that it has the necessary and sufficient wear resistance for practical use. On the other hand, in Comparative Example 7, the film peeled off during the test. This was thought to be because the film thickness of Comparative Example 7 was too thick to withstand the stress during sliding. From this result, it can be said that the thickness of the amorphous hard film of the present invention is preferably 0.08 to 10 μm.

  As described above, the sliding component according to the present invention has a low friction property equivalent to that of a conventional sliding component formed with an amorphous carbon film such as DLC when used in a non-lubricated or boundary lubricated environment. It has been demonstrated that it has wear resistance superior to that of the conventional sliding component.

1 ... sliding parts, 2 ... base material, 3 ... amorphous hard coating,
4 ... intermediate layer, 41 ... first intermediate layer, 42 ... second intermediate layer,
10, 20 ... friction and wear test equipment, 11 ... plate test piece, 12 ... ring test piece,
13 ... Heater, 14 ... Arm for torque measurement, 15 ... Load cell, 16 ... Bathtub,
17 ... immersion liquid, 18 ... oil for heat retention, 21 ... disc test piece, 22 ... ball test piece.

Claims (7)

It is a sliding component used in a non-lubricating or boundary lubrication environment, and is a sliding component in which an amorphous hard film is formed on a sliding surface of a base material constituting the sliding component,
The amorphous hard film contains at least boron, carbon, nitrogen and oxygen,
When the total of the boron, the carbon, the nitrogen and the oxygen is 100 atomic%,
The carbon content is 12 atomic% or more,
The nitrogen content is 10 atomic% or more,
The boron content is higher than the carbon and nitrogen content,
The oxygen content is 5-12 atomic%,
A sliding part, wherein the amorphous hard film has a thickness of 0.08 to 10 μm. The sliding component according to claim 1,
A sliding part, wherein the amorphous hard coating contains silicon instead of boron as a part of the boron. In the sliding component according to claim 1 or 2,
The amorphous hard film has a fine structure in which crystal particles having a diameter of 10 nm or less are dispersed in an amorphous matrix. In the sliding component according to any one of claims 1 to 3,
The amorphous hard film, when the total of the boron, the carbon, the nitrogen and the oxygen is 100 atomic parts,
A sliding component characterized by further containing 10 atomic parts or less of hydrogen and 8 atomic parts or less of argon. In the sliding component according to any one of claims 1 to 4,
The sliding component has a plurality of intermediate layers interposed between the amorphous hard film and the base material,
The plurality of intermediate layers are formed immediately above the base material and formed of a first intermediate layer made of one or more elements selected from silicon, chromium, titanium, and tungsten, and formed immediately above the first intermediate layer. A second intermediate layer comprising an element of one intermediate layer and an element constituting the amorphous hard film,
In the second intermediate layer, the content of the element constituting the amorphous hard film is gradually increased while the element content of the first intermediate layer is gradually decreased. In the sliding component according to any one of claims 1 to 5,
The sliding parts are arranged in a valve lifter, adjusting shim, cam, camshaft, rocker arm, tappet, piston, piston pin, piston ring, timing gear, timing chain, and fuel supply system arranged in the internal combustion engine. A sliding component characterized by being an injector, a plunger, a cylinder, a cam, or a vane. It is a manufacturing method of the sliding parts according to claim 1,
The formation of the amorphous hard film is performed on the sliding surface of the substrate by a reactive sputtering method using a non-equilibrium magnetron sputtering apparatus,
Using at least a boron carbide target as a source of boron and carbon components,
A method for producing a sliding component, wherein a mixed gas containing at least nitrogen and oxygen is used as a supply source of a nitrogen component and an oxygen component.

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