JP4990959B2 - Thick film DLC coated member and method for manufacturing the same - Google Patents

Description

  The present invention relates to a thick film DLC covering member and a method for manufacturing the same, and in particular, by modifying the mechanical, chemical and / or electrical properties of the DLC film by heat-treating the DLC film after film formation. And a proposal for an advantageous manufacturing method for this member.

  In recent years, a coating method for a hard film mainly composed of carbon and hydrogen has been put into practical use using a hydrocarbon-based gas as a film forming material, and is used in many industrial fields. This hard film containing carbon and hydrogen as main components is a mixture of amorphous diamond structure (SP3 structure) and graphite structure (SP2 structure), and is called diamond-like carbon, so-called DLC.

  Since this DLC film is hard and has a low coefficient of friction, it was initially applied to the surfaces of cutting tools, sliding members, and rotating members that require wear resistance. It is also used as a surface treatment film in the field.

  For example, when the DLC film is formed in a non-porous state, it exhibits excellent corrosion resistance against acids, alkalis, halogen compounds, and the like. It is used as a film having a good function of removing contaminants with respect to cleaning of the member with acid and pure water (Patent Documents 1 to 7).

Further, a technique for imparting higher lubricity and hydrophilicity to the film by imparting CF ₂ group and CF ₃ group in which F is bonded to the structure of C and H of the DLC film (Patent Documents 8 to 15) These technologies are used in the fields of magnetic disks and medical equipment. Furthermore, the excellent slip characteristic of the DLC film is applied for the surface treatment of the resin forming mold (Patent Documents 16 and 17).

  On the other hand, research and development of DLC film formation methods and apparatus have been conducted energetically. Recently, ionization deposition method, arc ion plating method, high frequency / high voltage pulse superposition type deposition method, plasma booster A DLC film forming method such as a plasma CVD method and an apparatus therefor have been developed. The DLC films formed by these methods are common in that they are amorphous, hard, and excellent in wear resistance. However, there is a difference in whether or not a film to be processed having a complicated shape can be uniformly formed, and a problem remains. However, among these forming methods, the high-frequency / high-voltage pulse superposition type plasma CVD method has the ability to form a coating with a uniform film thickness and can form a DLC film with a small initial residual stress. , Contributing to the development of new application fields.

  The inventors have improved and applied mechanical properties such as film quality, hardness, and friction coefficient of conventional DLC films by applying a high-frequency / high-voltage pulse superposition type plasma CVD method (hereinafter abbreviated as “plasma CVD method”). The expansion of the scope has promoted the development of general-purpose engineering fields. As a result, the DLC film formed by the application of the above plasma CVD method has a small residual stress and a hardness lower than that of the DLC film obtained by other methods, but it is uniform even for a member having a complicated shape. This is effective in forming a simple DLC film. For example, this technique includes corrosion resistance, plasma resistance, erosion resistance (Patent Documents 18 to 20) to members for semiconductor processing devices, filling of open pores of a sprayed coating (Patent Documents 21 and 22), pump impellers, compressor blades It can be applied to a technique for the purpose of providing anticorrosion / antifouling measures (Patent Documents 23 to 26).

  Next, as another prior patent document belonging to the technology of the present invention, there is one disclosed in Patent Document 27. This technique is a method for reducing the coefficient of friction by reducing C—Hx bonds (x = 1, 2, 3) existing on the surface of an amorphous DLC film by gas ion bombardment treatment. It is disclosed to heat-treat in vacuum or in a gas atmosphere. This technique is aimed at reducing the frictional resistance on the surface of the DLC film. For this reason, the thickness of about 0.01 to 0.1 μm is removed from the surface of the DLC film, or the C—Hx bond on the surface of the DLC film is reduced. It is aimed at. However, this technique is limited to the extremely limited modification of the DLC film, and is not a technique for modifying the mechanical, electrical, and chemical properties of the entire DLC film.

JP-A-9-313926 JP 2002-110655 A JP 2003-133149 A JP 2000-262989 A JP 2000-70884 A JP 2000-265945 A JP 2003-209086 A Japanese Patent Laid-Open No. 11-158361 Japanese Patent Laid-Open No. 11-330066 JP-A-9-44841 Japanese Patent Laid-Open No. 10-68083 Japanese Patent Laid-Open No. 10-198953 JP 2000-96233 A JP 2003-310744 A JP 2003-217845 A JP 2004-130775 A JP 2004-315876 A JP 2007-324353 A JP 2006-89822 A JP 2006-118053 A JP 2007-32194 A JP 2007-231781 A JP 2007-327349 A JP 2007-327350 A JP 2007-231781 A JP 2009-138664 A JP 2008-144273 A

Various properties of a conventional DLC film are determined by the film forming process, film forming conditions, and the type of hydrocarbon gas that is a film forming raw material. For this reason, even if a DLC film is formed, it does not exhibit a sufficient function in all fields, for example, a field in which some processing is performed on the DLC film. Some of the required characteristics cannot be satisfied and cannot be used. That is,
(A) To change the residual stress of the DLC film after film formation,
(B) When it is desired to change the mechanical properties of the DLC film represented by hardness after film formation,
(C) When it is desired to change the electrical characteristics of the DLC film represented by the electrical resistance value,
(D) When it is desired to change not only the surface frictional resistance value of the DLC film but also the adhesion characteristics under a sliding environment,
(E) To change the adhesion of the DLC film,
As for the method of always satisfying the required characteristics such as these for the DLC film after the film formation, the actual situation is that it has not been put into practical use yet.

  Therefore, the present invention provides a DLC coated member in which various properties of a DLC film formed by a conventional technique are modified by a secondary treatment according to required characteristics in each application to improve application suitability. And to propose an advantageous manufacturing method thereof.

  In order to solve the above-mentioned problems, the present invention proposes a technique for secondarily modifying the characteristics of a DLC film by subjecting a DLC film formed under a predetermined condition to a predetermined heat treatment. is there.

In the present invention,
(1) The DLC film is heat-treated in one or more atmospheres in oxygen gas, air, inert gas, or vacuum.
(2) By performing the heat treatment, the mechanical, electrical, and chemical properties of the DLC film are increased by increasing the bonding force between carbon and hydrogen, which are the main components constituting the DLC film, and by the desorption reaction of hydrogen gas. The property is modified by secondary change.
(3) The heat treatment becomes faster as the temperature becomes higher and the film reforming characteristics change greatly. However, if the treatment temperature is increased more than necessary, the original function of DLC is lost. Investigate changes in temperature and film and set the maximum allowable heat treatment temperature and treatment time.
That is important.

The present invention developed based on such knowledge is a member obtained by coating a thick film DLC formed by a plasma CVD method having a film thickness of more than 3 μm on the surface of a substrate. Is a deposited layer of ultrafine particles having a carbon content of 13 to 30 atomic% and the balance being carbon, and an initial residual stress of less than 1.0 GPa at a temperature not lower than the film forming temperature and not higher than 550 ° C. for 0.1 to 30 hours. by heat treatment carried out in conditions, residual stress than 1.0 GPa, a thick DLC coating member, wherein the hardness (Hv) is obtained by heat treatment DL C film 700-2800.

Further, the present invention has an initial residual stress of 1 formed by a deposition layer of ultrafine particles having a film thickness of more than 3 μm, hydrogen of 13 to 30 atomic%, and the balance being carbon, which is formed on the surface of the substrate by a plasma CVD method. When a thick film DLC of less than 0.0 GPa and an initial residual stress of less than 1.0 GPa are subjected to a heat treatment for 0.1 to 30 hours at a temperature not lower than the film forming temperature and not higher than 550 ° C., the residual stress becomes 1 It is a manufacturing method of the thick film DLC covering member characterized by making it the heat treatment DLC film of 0.0 GPa or more and hardness (Hv) of 700-2800.

In the present invention, in particular,
(1) The post-heat treatment thick film DLC is a film to be processed whose surface is irradiated with a laser beam heat source or an electron beam heat source,
(2) The base material is an inorganic compound or a nonmetallic organic compound that is either a metal or a nonmetal,
(3) The heat treatment of the thick film DLC is performed in one or more atmospheres selected from oxygen gas, air, inert gas, and vacuum,
(4) The post-heat treatment thick film DLC has a surface to be processed that is irradiated with a laser beam heat source or an electron beam heat source,
However, it is desirable to adopt as the above solution.

When the present invention is configured as described above, the following effects can be expected.
(1) By performing a predetermined heat treatment on the thick film DLC after film formation, the characteristics of the film can be secondarily changed to suit the suitability as a film to be processed. That is, the untreated DLC coated member immediately after film formation is greatly improved in various properties such as hardness, friction coefficient, electrical properties, and corrosion resistance, and the use as a DLC coated member is expanded. In particular, even if the use and characteristics of the DLC film are predetermined by the manufacturing process, conditions, raw materials, etc. of the DLC film, according to the method of the present invention, the properties of the DLC film are heat treated. Thus, the properties of the DLC film can be modified to suit the application as the application field expands.
(2) The heat treatment of the DLC film can be performed in oxygen gas, air, inert gas, or vacuum, and the temperature of the heat treatment is also a low temperature below the decomposition temperature of the DLC film (about 550 ° C.). Moreover, since the processing time can be processed within about 30 hours, it is rich in productivity and economical.
(3) Since the thick film DLC after heat treatment can be easily formed into a sculpture groove by a laser beam heat source and is formed directly on the DLC film having excellent wear resistance, the groove does not lose its shape. Since the groove shape can be accurately maintained over a long period of time, it can be used as an imprint member having a long life.

It is a schematic diagram which shows an example of the process of the heat processing of the DLC film which concerns on this invention. It is the schematic of the plasma CVD apparatus for DLC film coating formation suitable for this invention. It is a thermal analysis curve of a DLC film. It is a basic diagram which shows the appearance of the test piece for residual stress measurement of a DLC film, and its displacement. It is a graph which shows the relationship between the heating temperature and time by heat processing of a DLC film, and hardness. It is an enlarged SEM image (linear engraving) of the surface of the DLC film engraved with a laser beam heat source. It is the expansion SEM image (pocket type engraving) of the DLC film surface engraved by the laser beam heat source. It is explanatory drawing for measuring the volume resistivity of a DLC film. It is a graph of the measured value of the volume resistivity of a DLC film in the temperature range from room temperature to 160 degreeC. It is a graph of the measured value of the volume resistivity in the room temperature state of the DLC film in the temperature range from 100 degreeC to 1600 degreeC.

  FIG. 1 shows a series of process examples in which a DLC film is formed on a substrate surface directly or indirectly through an undercoat, followed by heat treatment, and then processing on the film surface. . Hereinafter, according to the order of this process example, the manufacturing method of the present invention and the member of the present invention will be specifically described.

(1) Substrate for coating a DLC film The following are recommended as a substrate for coating a DLC film.
(A) Metal base material: As the metal base material, Al, Ti, Nb, Ta, Si, W other than ordinary steel, special steel such as stainless steel including Cr and heat-resistant steel, Ni base alloy and Co base alloy In addition, metals such as Mo and alloys thereof can be used.
(B) Inorganic non-metallic substrate: As the non-metallic substrate, sintered bodies such as carbon, graphite, quartz, glass, carbide, silicide and nitride, and thin films can be used.
(C) Organic base materials: Organic base materials include phenol, melamine, epoxy, polyurethane, silicone and other thermosetting resins, polyethylene, polypropylene, polystyrene, acrylic nitrile, butadiene and other thermoplastic resins, natural and synthetic rubbers Etc. can be used.

  Note that some of the base materials such as Ni and its alloys, Cu and its alloys, non-metal base materials, and organic base materials tend to have poor adhesion to the DLC film. In advance, a metal / alloy such as Cr, Nb, Ta, Si, or the like by electroplating, chemical plating (electroless plating), CVD, PVD, etc. It is desirable to coat these metal carbide thin films to a thickness of 0.1 to 3 μm. This is because these undercoats exhibit good adhesion to the substrate and also show strong adhesion to the DLC film applied on the surface of the undercoat. If the thickness of these undercoats is less than 0.1 μm, it is difficult to obtain a uniform thickness. On the other hand, an undercoat thicker than 3 μm requires a long time and is too thick. However, the effect will be saturated.

  However, since the organic base material has low heat resistance, it is considered that deterioration of the base material itself becomes a problem when heat treatment described later is performed at a temperature of 200 ° C. or higher. Even in this case, according to the knowledge of the inventors, it is known that if the heat treatment is 180 ° C. or less, the modification effect by the DLC film is greater than the deterioration of the substrate. When it is targeted, heat treatment at 180 ° C. or lower is recommended.

(2) DLC film coating formation method As a method of forming a DLC film on the surface of a substrate (including a substrate with an undercoat), a plasma CVD method, an ionized vapor deposition method, an arc ion plating method, a plasma booster method, etc. The method is known. The properties of the DLC film to be formed usually vary depending on the coating formation method and its conditions. In general, when an attempt is made to manufacture a DLC film having a low hardness or a low surface friction coefficient, the residual stress during film formation tends to increase. Therefore, if an attempt is made to grow the DLC film thick, the residual stress value inside the film increases, sometimes it becomes greater than the bonding force with the substrate, and the film may peel off from the substrate. According to the inventors' experience, the maximum thickness of the hard DLC film is less than 3 μm. Here, the hardness of the hard DLC film is Hv: 3000 or more.

  However, although the DLC film containing a relatively large amount of hydrogen has a slightly reduced film hardness, the residual stress value tends to be suppressed, so that a thick film can be easily formed. According to the experiments by the inventors, when the hydrogen content is controlled within the range of 13 to 30 at%, a thick film of about 80 μm can be formed although it takes time to form the film. Therefore, in the case of such a thick film DLC, the surface thereof can be polished or engraved by irradiating a laser beam heat source. The method of the present invention can be suitably used when a thick film DLC having a small residual stress is formed.

  Hereinafter, a film forming method suitable for forming the thick film DLC film according to the present invention will be described. The method described below is a technique similar to the method disclosed in Japanese Patent Application Laid-Open No. 2008-231520 proposed by the present inventors, and a material (substrate to be processed) is used as a processing container (counter electrode) during film formation. In contrast, while maintaining a relatively negative potential, positively charged hydrocarbon radicals and molecular ions in the gas phase are electrochemically attracted to the substrate surface, and finally carbon and hydrogen are attracted. A technology that deposits amorphous solid fine particles as the main component on the surface, and in order to effectively execute such a phenomenon, a technology called a plasma CVD method that superimposes high frequency and plasma. It is.

  FIG. 2 is a schematic configuration diagram of a plasma CVD apparatus for thickly coating an amorphous DLC film mainly composed of carbon and hydrogen. This apparatus includes a grounded reaction vessel 21 and an organic gas (mainly hydrocarbon gas) introduction device (not shown) for film formation connected to the reaction vessel via a valve 27a and a valve 27b. ), A vacuum pump (not shown) for evacuating the reaction vessel, a conductor 23 connected to a base material 22 which is an object to be processed disposed at a predetermined position in the reaction vessel, and an introduction terminal 29 A high voltage pulse generating power source 24 for applying a high voltage pulse and a plasma generating power source 25 for generating a plasma around the substrate 21 by applying a high frequency to the conductor 23 via the high voltage introducing portion 29. , And a superimposing device 26 used for applying a pulse and a high frequency simultaneously.

In order to form a DLC film on the surface of a substrate to be processed using this plasma CVD apparatus, first, the substrate is placed at a predetermined position in the reaction vessel, and a vacuum device is operated to air in the reaction vessel. After degassing and degassing, a carbon hydrogen-based organic gas is introduced into the reaction vessel by a gas introduction device. Prior to the introduction of organic gas, Ar gas, H ₂ gas, etc. are introduced, and then a high frequency voltage is applied to clean the surface of the object to be processed by Ar or H ion bombardment (ion bombardment). It is preferable to apply.

  Next, high frequency power from a plasma generating power source is applied to the substrate. Since the reaction vessel is in an electrically neutral state by the ground wire 28, the base material is relatively negatively charged. For this reason, positive ions existing in the plasma of the hydrocarbon gas are generated relatively evenly over the entire surface of the base material, and promote the leveling precipitation of the DLC film.

  When a high voltage pulse (negative high voltage pulse) is applied to the substrate from a high voltage pulse generator, positive ions in the plasma of the hydrocarbon gas are electrically attracted and adsorbed on the surface of the substrate to be treated. The Rukoto. By such an operation, ultrafine particles of DLC are deposited on the surface of the object to be processed to form a film. That is, in the reaction vessel 21, a DLC film mainly composed of amorphous carbon / hydrogen solids mainly composed of carbon and hydrogen is vapor-deposited on the surface of the substrate to be treated to cover it. It is estimated that it is formed in this way.

As the hydrocarbon-based gas for film formation introduced into the reaction vessel of this plasma CVD apparatus, organic hydrocarbon gases as shown in the following (a) to (b) are used alone or in combination of two or more kinds: Is used.
(I) Gas phase state at room temperature (18 ° C.) CH ₄ , CH ₂ CH ₂ , C ₂ H ₂ , CH ₃ CH ₂ CH ₃ , CH ₃ CH ₂ CH ₂ CH ₃
(B) Liquid phase at normal temperature C ₆ H ₅ CH ₃ , C ₆ H ₅ CH ₂ CH, C ₆ H ₄ (CH ₃ ) ₂ , CH ₃ (CH ₂ ) ₄ CH ₃ , C ₆ H ₁₂ , C ₆ H ₄ Cl

  The above-mentioned carbon-hydrogen gas can be introduced into the reaction vessel as it is in the gas phase at room temperature, but the compound in the liquid phase can be heated to gasify the gas (vapor). Can be fed into the reaction vessel.

(3) Content ratio of carbon and hydrogen constituting the DLC film according to the present invention A general DLC film generates a large residual stress at the time of film formation, and thus is hard and excellent in wear resistance but lacks flexibility. There is. Therefore, it is difficult to form a thick film, and many local micro defects are likely to be generated in the generated DLC film, and even if heat treatment is performed, it is caused by a difference in the thermal expansion coefficient of the base material / DLC film. The generation of thermal stress makes it easy to peel off particularly in the case of a thick film.

  As a countermeasure, in the present invention, attention is paid to the ratio of carbon to hydrogen forming the DLC film. In particular, by controlling the hydrogen content to 13 to 30 atomic% of the whole, the original characteristic of the hard DLC film is maintained. However, flexibility was given to the DLC film. Specifically, the hydrogen content contained in the DLC film is 13 to 30 atomic%, and the balance is the carbon content. Note that the formation of the DLC film having such a composition can be achieved by mixing compounds having different hydrogen and hydrogen content ratios in the hydrocarbon-based gas for film formation.

  Thus, since the surface hardness of the DLC film having a high hydrogen content is micro Vickers hardness and Hv: about 700 to 2800, it is softer than the DLC film formed on tool steel or the like. It is flexible enough to withstand some deformation.

  In the method of the present invention, the DLC film formed on the surface of the base material has a thickness of more than 3 μm and 50 μm or less. When the DLC film thickness is 3 μm or less, the oxygen gas (air) in the atmosphere penetrates into the inside through the defective part of the film through the micro defects of the film during the heat treatment, and oxidizes the base material. Is likely to peel off. On the other hand, if the film thickness is thicker than 50 μm, it takes a long time to form the film, which may cause an increase in production cost or a decrease in bonding force with the substrate due to an increase in residual stress accompanying the growth of the DLC film. Can be considered.

  In the present invention, when the base material is a non-electric conductive synthetic resin plate or sheet or film thereof, in order to directly coat the surface of the base material with the DLC film, these are attached to a metal plate or the like. Then, the DLC film can be formed on the surface of these synthetic resin bodies in the same manner as the metal electrode. Further, in the plasma CVD apparatus shown in FIG. 4, it is possible to form a DLC film on the surface of the non-electric conductor by controlling the pulse waveform to only positive.

  Note that in the plasma CVD apparatus, ion implantation of metal or the like is performed on the object 22 by changing the output power of the high voltage pulse generation power supply 24 as shown in the following (a) to (d). Can do. For example, when the object to be processed is metallic, if a metal ion having a low free energy for generating carbides such as Ti, Si, Cr, Nb, Mo, Zr, and C is implanted, the DLC film is formed on the surface of the DLC film. It is possible to improve the adhesion.

(A) When ion implantation is focused on: 10 to 40 kV
(B) When performing both ion implantation and film formation: 5 to 20 kV
(C) When only film formation is performed: several hundred V to several kV
(D) When focusing on sputtering, etc .: several hundred V to several kV
(E) In the high voltage pulse generation source 24, it is also possible to repeat the pulse width: 1 μmsec to 10 msec, the number of pulses: 1 to plural times.
(F) The output frequency of the high frequency power of the plasma generating power supply 25 can be changed in the range of several tens of kHz to several GHz.

(4) Heat treatment of DLC film A DLC film, that is, a heat treatment method for a member on which this film is coated will be described. The heat treatment temperature of the DLC film is determined by the heat resistant temperature of the DLC film and the substrate, the heat treatment atmosphere, and the like. For example, FIG. 3 shows a thermal analysis curve of a DLC film formed by a plasma CVD method (carbon content 87 atomic%, hydrogen content 13 atomic%). As is apparent from this figure, the DLC film heated in the air does not change in weight loss at all up to 550 ° C., but the weight reduction becomes remarkable from around 550 ° C. That is, it can be seen that the DLC film decomposes at 550 ° C. or higher. Such a change in the air is presumed to be caused by the following chemical reaction due to the DLC film and oxygen (O ₂ ) in the air.
Carbon (C) in the DLC film + oxygen in the air (O ₂ ) → carbon dioxide (CO ₂ )
Hydrogen (H) in the DLC film + oxygen (O ₂ ) in the air → water vapor (H ₂ O)
Reaction in which hydrogen (H) in the DLC film is desorbed as hydrogen gas (H ₂ )

On the other hand, in the thermal analysis curve in the inert gas (Ar), the temperature at which the weight loss of the DLC film begins to decrease tends to be somewhat higher than the treatment in air. It can be ignored. Rather, the rate of weight loss of the DLC film starting from around 550 ° C. is slower than in air. The cause of this is that the inert gas does not contain oxygen gas. Therefore, in the decomposition reaction of the DLC film, only hydrogen gas is released. As a result, there is no reaction in which the carbon component disappears as CO ₂ gas. This is probably because the carbon component remains after graphitization (graphitization).

  From the above results, it is presumed that the heat treatment atmosphere of the DLC film exhibits a weight reduction curve similar to that in the inert gas, for example, even in a vacuum if the atmosphere does not contain oxygen gas.

  From the above description and the results shown in FIG. 3, the physicochemical characteristics can be changed without causing deterioration of the film quality by performing the heat treatment of the DLC film with the upper limit being around 550 ° C. That is, for a DLC film having a hydrogen content of 13 to 30 atomic% and the balance being carbon (70 to 78 atomic%), when performing heat treatment, the maximum temperature is about 550 ° C., while the minimum temperature is the same as the DLC film. It is preferable to set the temperature of the base material to about 80 ° C., which is suitable for formation by plasma CVD.

  Next, as is apparent from the thermal analysis curve of the DLC film, the heat treatment time changes in a short time as the temperature increases, and therefore, in the range of about 5 minutes to 30 hours in consideration of practical and safety. It is desirable to change at.

(5) Hardness of DLC film after heat treatment Compared with a general DLC film, the DLC film suitable for the present invention is characterized by being relatively soft and having a high hydrogen content. In particular, a film formed by plasma CVD is heat-treated to give a film hardness (Hv) of about 1100 to 2700, and on average, as shown in FIG. However, the temperature is about 300 ° C. to 600 ° C., the time is 1 to 24 hours, and shows about 1300 to 1800, and it is understood that the film to be processed has both hardness and softness. This can be said to be a film suitable for forming engraving grooves by laser beam irradiation described later.

(6) Residual stress of DLC film suitable for heat treatment A DLC film, which is a deposited layer of amorphous carbon hydrogen solid particulates deposited from a gaseous hydrocarbon gas, inevitably generates residual stress. A DLC film containing such a residual stress has a larger residual stress as the film thickness increases. Finally, the residual stress becomes larger than the adhesion strength of the film, and the DLC film is peeled off. At present, many kinds of apparatuses and processes have been developed as a DLC film coating formation method. One of the application conditions is a limit film thickness determined by the residual stress of the DLC film.

  In particular, when a large amount of DLC film containing a large amount of hydrogen (13 to 30 atomic%) according to the present invention can be formed even if a film exceeding 10 μm can be formed, Since a large thermal stress is generated in the film due to the difference in thermal expansion coefficient between the substrate and the base material, it is necessary to consider this countermeasure.

Therefore, in the present invention, the allowable value of the initial residual stress (residual stress at the time of film formation) of the DLC film capable of suitably performing the heat treatment was obtained by the following method.
As shown in FIG. 4, the evaluation of the residual stress of the DLC film is performed on one surface of a strip-shaped thin quartz substrate (size: width 5 mm × length 500 mm × thickness 0.5 mm) to which one end of the test piece is fixed. The residual stress of the film is obtained by forming the DLC film and measuring the displacement (δ) of the quartz substrate before and after the film formation. Specifically, the residual stress (σ) is calculated by the following Stoney equation. Calculated.

Ｅ：基板のヤング率＝７６．２ＧＰａ
ｖ：基板のポアソン比＝０．１４
ｂ：基板の厚さ＝０．５ｍｍ
ｌ：ＤＬＣ膜が形成された基板の長さ
δ：変位量
ｄ：ＤＬＣの膜厚

E: Young's modulus of substrate = 76.2 GPa
v: Poisson's ratio of substrate = 0.14
b: substrate thickness = 0.5 mm
l: length of substrate on which DLC film is formed δ: displacement d: film thickness of DLC

  Table 1 shows an initial residual stress value and a post-heat treatment residual stress value obtained by the above-described method for a DLC film (hydrogen 13 atomic%, carbon 87 atomic%) formed by various film forming processes. As is clear from these results, the initial residual stress of the DLC film formed by a method such as arc ion plating or ionized vapor deposition is 13 to 20 GPa. On the other hand, the initial residual stress of the DLC film formed by the plasma CVD method is in the range of 0.3 to 0.98 GPa. That is, it can be seen that the initial residual stress of the DLC film conforming to the present invention (according to the plasma CVD method) must be a very small film of 1 GPa or less. Therefore, the DLC film formed by the plasma CVD method according to the present invention containing a large amount of hydrogen can sufficiently cope with a thick film or a case where a heat treatment is performed thereafter. It can be seen that it is.

  As shown in Table 1, when the DLC film having a hydrogen content of 13 atomic% is formed, the maximum formation thickness of the DLC film is about 50 μm although the film formation time becomes longer if the plasma CVD method is used. However, it was difficult to form a film having a thickness of 3 μm or more by other film forming methods.

  Furthermore, when the surface hardness of each DLC film shown in Table 1 was measured, the DLC film formed by the plasma CVD method has a micro Vickers hardness (Hv) of about 700 to 2800 and an average of about 1100. On the other hand, the hardness of the DLC film formed by another method is Hv = 3000 or more, which is found to be hard. From these results, it can be seen that the hardness of the DLC film is large even if the hydrogen content is increased in the case of the DLC film according to the ion plating method or ionized vapor deposition, as compared with the plasma CVD method. It can be seen that the initial residual stress value at time also increases.

  Then, when each said DLC film was heat-processed, the residual stress value after heat processing became as shown in Table 1, respectively. In particular, it is 1 to 5 GPa in the case of a DLC film formed by plasma CVD, whereas it is 20 to 35 GPa in other methods. From this, the DLC film formed under the method according to the present invention has a post-heat treatment residual stress of over 1 GPa, but can be suppressed to about 5 GPa, and the hardness is not so high. As will be described later, this is effective for processing such as laser irradiation and electron beam irradiation.

  In addition, when the specimen after the residual stress measurement was observed with a magnifying glass, the film formed by the arc ion plating method and the ion vapor deposition method had a lot of minute delamination, and there was a tendency to have poor heat resistance. confirmed.

(7) Thick film DLC as a film to be processed
The DLC film formed on the surface of the substrate by the method described above is preferably formed in a thick film of 3 to 50 μm when this is used as a film to be processed. The reason for this is that when the film thickness is 3 μm or less, for example, in the case of a laser beam engraving groove obtained by engraving this with a laser beam heat source, the aspect ratio of this groove cannot be increased, and the substrate surface This is because it is easily affected by “undulation” and slight deformation, and hinders the groove formation of the imprint member. Moreover, there is a possibility that the laser beam engraving groove completely penetrates the DLC film and reaches the base material due to a slight deviation in engraving processing accuracy by the laser beam heat source and a difference in the absorption rate of the laser generated locally in the DLC film. Because there is. On the other hand, in order to form a film thicker than 50 μm, it takes a long time, resulting in an increase in production cost, and there is a risk of a decrease in bonding strength with the substrate due to an increase in residual stress accompanying the growth of the DLC film. It is possible.

  When a DLC film having a large thickness (for example, 10 μm or more) is formed, sometimes a plurality of minute circular protrusions (for example, Rz ≦ 1.0 μm) are generated on the surface. In such a case, it is preferable to finish the surface to a smooth surface (for example, Ra ≦ 0.1 μm) by performing bubbing (polishing) or the like in order to remove the circular protrusions as necessary. .

(A) Overview of laser beam engraving This process is performed by directly irradiating the surface of the DLC film with a laser beam after the heat treatment after the coating of the thick DLC film on the surface of the substrate and the heat treatment are finished. Sculpting an engineering pattern.

A commercially available laser processing light source such as a CO ₂ laser, YAG laser, Ar laser, semiconductor laser, or excimer laser can be used as a laser light source in this treatment. It is recommended that the resulting engineering pattern engraving be performed automatically by a computer with a pre-programmed computer, but depending on the size of the engraving groove (width and depth), a laser beam condensing lens, etc. Can be adjusted manually.

Engraving on the DLC film by this laser beam is performed by irradiation with a laser beam heat source, but since irradiation (heating) is performed locally, heat is not transmitted to the non-irradiated part, and irradiation is performed. Only in the local part of (heating), the DLC component becomes a gas such as CO ₂ and H ₂ O and diffuses. As a result, on the DLC film surface, there is no adhesion of residual residue especially around the laser beam engraving groove, and a precise and accurate engraving groove pattern can be formed without affecting other parts. Can do.

  6 and 7 show SEM images of the appearance of a DLC film engraved with a laser beam by the method of the present invention. As the heat source of the laser beam in the illustrated example, the heat source having the following specifications is used, but it may have a relatively low output as compared with that applied to metal or ceramic engraving.

Laser output: 50W ~ 1KW
Pulse frequency: 10000 Mz to 50000 Hz
Progression speed: 0.1 to 500 mm / min

<Example 1>
This example reports the results of investigating the corrosion resistance of a DLC film using a salt spray test method after heat treatment using films with different hydrogen contents as samples.

(1) Test film As a test film, a 12 μm thick DLC film having a hydrogen content ranging from 13 to 35 atomic% was coated on the surface of SUS410 steel (dimensions: 50 mm × 50 mm × 3.5 mm). A thing was used.

(2) Heat treatment conditions for the film Atmosphere: In air Temperature: 300 ° C, 450 ° C, 550 ° C, 600 ° C
Time: 3 hours

(3) Test method The DLC film subjected to the above heat treatment was examined for the presence or absence of the corrosion resistance constant price of the film by the heat treatment by the salt spray test method specified in JIS 2371. The salt spray test time is 96 hours.

(4) Test results The test results are summarized in Table 2. As is clear from this result, no red rust is observed even when the hydrogen content of the DLC film is changed to 13 to 35 atomic% or heated at a temperature of 550 ° C. or less, and good corrosion resistance is maintained. I was able to confirm. However, in the DLC film heated to 600 ° C., the occurrence of red rust was observed in all the films tested, and it was considered that the defects of the film were caused by heating. In addition, test piece No. with high hydrogen content. In the DLC film No. 6, even when heated at 550 ° C., the occurrence of traces of red rust is recognized, so the occurrence of minute defects in the film is estimated. A DLC film with a high hydrogen content is generally softer than other DLC films and exhibits excellent flexibility against bending deformation, but under high-temperature heating conditions, the hydrogen desorption reaction from the DLC film There is a tendency that the occurrence rate of micro defects due to is increased.

<Example 2>
This example shows the results of investigation on changes in heat treatment temperature and hardness of the DLC film.

(1) DLC film to be tested A DLC film having a thickness of 10 μm was formed on the entire surface of SUS304 steel (size: 50 mm × 50 mm × 5 mm). The composition of the DLC film is 20 atomic% hydrogen and the remaining carbon.

(2) Heating conditions Atmosphere: In air Temperature: Room temperature (20 ° C), 300 ° C, 350 ° C, 550 ° C, 600 ° C
Time: 1-60 hours

(3) Hardness tester Using a Macro Vickers tester, 10 points were measured per sample under the condition of 5N load, and the average value was calculated. The hardness was measured after heating at any heating temperature for a predetermined time and then cooling to room temperature.

(4) Test results The test results are shown in FIG. As is clear from this result, the hardness of the test DLC film at room temperature was Hv: 1150, but when heated to the respective temperatures, the hardness increased in about 1 hour, and the tendency was the heating temperature. The higher the value, the more prominent. However, the hardness of the DLC film heated to 600 ° C. showed a sharp decrease in hardness after 50 hours. This is probably because the DLC film is dehydrogenated by heating and the carbon component of the DLC film is graphitized (graphitization). Even if the heating atmosphere of the DLC film was changed to Ar gas or vacuum, the hardening phenomenon of the DLC film due to heating was recognized, so that it was possible to adjust the hardness of the DLC film by heat treatment.

<Example 3>
In this example, the change in the coefficient of friction of the DLC film after heat treatment was investigated.

(1) DLC film to be tested A 10 μm thick DLC film was formed on the surface of SUS304 steel (size: diameter 50 mm × thickness 6 mm). At that time, the hydrogen content contained in the DLC film was 13 Varyed to ˜20 atomic%.

(2) Conditions for heat treatment of test film Atmosphere: In air Temperature: Room temperature (20 ° C), 300 ° C, 450 ° C
Time: 1 hour

(3) Test method The coefficient of friction of the DLC film after heat treatment was measured using the following apparatus and conditions.
Ball on Disk type friction coefficient measuring device (SZ-FT-93B type manufactured by Shinko Machine Co., Ltd.)
Test load 5N (0.5kgf)
Rotational speed 400r. p. m.
Turning radius 5mm
Test time 15min
Wear material Al ball (3/16 inch diameter)
Comparative example Cr plating WC-12% Co sprayed coating SUJ2 (JIS G4805, high carbon chromium bearing steel)

(4) Test results Table 3 shows the test results. As is apparent from the results, the Cr plating, the WC-12% Co sprayed coating and the SUJ2 steel sheet, whose friction coefficients were measured under the same conditions as comparative examples, showed a high friction coefficient of 0.3 to 0.8. After the heat treatment, the DLC film (Nos. 1 to 5) maintains a low coefficient of friction of 0.1 to 0.2 even after being heated to 300 ° C. and 450 ° C. as well as normal temperature. As a result, prospects for practical application were obtained.

<Example 4>
In this example, the electrical characteristics of the DLC film after heat treatment were investigated.

(1) Test DLC film As a test DLC film, a DLC film made of SUS304 steel (dimension: diameter 50 mm × thickness 10 mm) with a hydrogen content of 18 atomic% and the balance carbon was formed to a thickness of 18 μm. Things were made.

(2) Heat treatment condition of test film Prior to measurement of volume resistivity, the test film was heat-treated under the following conditions.
Atmosphere: Temperature in air: 100 ° C, 200 ° C, 300 ° C, 400 ° C, 500 ° C, 600 ° C
Time: 1 hour

(3) Test method The volume resistivity of the DLC film was measured by the following apparatus and conditions.
Test standard Compliant with JIS K6911 Superinsulation resistance meter R8340A (manufactured by ADVANTEST)
Digital multimeter R6441A (manufactured by ADVANTEST)
Test Fixture R12702A (manufactured by ADVANTEST)
Electrode shape Main electrode φ10mm
SUS304 steel plate is used for the counter electrode Electrode material Main electrode: Applied voltage of conductive paste 10V / min
Test environment 22 ℃ / 60% RH

  FIG. 8 shows a procedure for measuring the volume resistivity of the DLC film. The base electrode 81 of SUS304 steel is used as a positive electrode, and the negative electrode 83 of SUS304 steel (φ10 mm) of the same quality as the base material is formed on the DLC film via the conductive paste 84 on the surface of the DLC film 82 formed on the surface. Adhere closely. Then, the base material 81 and the counter electrode 83 were connected by the direct current power supply 85 with the conducting wire 86, the current value flowing when a voltage was loaded between the electrodes was measured with an ammeter 87, and the volume resistivity was obtained from the following equation. In actual measurement, a guard electrode was provided at the end of the base material in order to prevent current from the end of the base material, but it was omitted here.

ここで、Ｐｖ：体積抵抗率（Ω・ｃｍ）
ｄ ：主電極の直径（２．５４ｃｍ）
ｔ ：試験基材の厚さ（ｃｍ）
Ｒｖ：体積抵抗（Ω）
π ：円周率

Where Pv: volume resistivity (Ω · cm)
d: Diameter of main electrode (2.54 cm)
t: thickness of test substrate (cm)
Rv: Volume resistance (Ω)
π: Pi ratio

(4) Test Results FIG. 9 shows the results of measuring the electrical resistivity of the DLC film immediately after film formation performed as a preliminary test in a state heated to room temperature (20 ° C.) to 160 ° C. According to this result, it can be seen that the electrical resistivity of the DLC film after heat treatment decreases linearly as the temperature increases. In this experimental apparatus, since it was impossible to measure the electrical resistivity at a high temperature of 160 ° C. or higher, the maximum temperature was set to 160 ° C.

  Next, FIG. 10 shows the results of measuring the electrical resistivity of a DLC film that was heat-treated at each temperature and then cooled to room temperature (20 ° C.). According to this measurement result, even if a heat treatment of 300 ° C. or lower is applied, it returns to the initial value of electrical resistivity when cooled to room temperature, but when exposed to a higher temperature, the electrical resistivity is decreased even when cooled to room temperature. Was found to maintain a low electrical resistance value without returning to the value before heating. From the above results, it was confirmed that the heat treatment of the DLC film has a relatively sensitive influence on the electrical property value of the film. In particular, it was found that a DLC film having a lower electrical resistivity than a DLC film before heat treatment can be provided by heat treatment at 300 ° C. or higher.

The technology of the present invention is expected to be used in the following industrial fields including fields where current DLC films are used.
a. In the machine industry, machine tools, looms, rotating machines such as pump blowers, film sheets such as plastic carbon, and manufacturing machines and devices such as fibers, cameras, optical equipment, printing machine devices b. In the electric machinery industry, home appliances such as TVs, radios, washing machines, refrigerators, air conditioners, office equipment such as personal computers and copiers, and communication / reception equipment c. In the semiconductor industry, precision polishing and processing equipment for Si, glass, etc. d. Aseptic and culture parts required in the fields of bio, biochemistry, medicine and pharmacy Various parts used in chemical plants, petrochemicals, oil refineries, etc. It can be used as a film that responds to electrical and chemical performance.
e. The technique for forming a fine engraving groove by irradiating a laser beam to a DLC film according to the present invention can be applied to printing intaglio and letterpress engraving in addition to the imprint member manufacturing technique. It can also be used as a technique for forming a lubricating oil passage by forming a DLC film on a sliding part such as a bearing or shaft of a mechanical device and then processing a spiral groove on the film with a laser beam heat source. .

21 Reaction vessel 22 Base material 23 Conductor 24 High voltage pulse generating power source 25 Plasma generating power source 26 Superimposing device 27a Valve 27b Valve 28 Ground 29 Introduction terminal 81 Base material (SUS304 steel) + electrode 82 Test DLC film 83 Counter electrode (SUS304 steel) ) -Pole 84 Conductive paste 85 DC power supply 86 Conductor 87 Ammeter

Claims (6)

In a member formed by coating the surface of a base material with a thick film DLC formed by a plasma CVD method having a film thickness of more than 3 μm, the thick film DLC is an ultra-thin film in which hydrogen is 13 to 30 atomic% and the balance is carbon. A residual layer having a residual stress of 1.0 GPa is obtained by heat treatment performed on a deposited layer of fine particles having an initial residual stress of less than 1.0 GPa at a temperature not lower than the film forming temperature and not higher than 550 ° C. for 0.1 to 30 hours. above, the thick film DLC coating member hardness (Hv) is characterized in that is obtained by heat treatment DL C film 700-2800. 2. The thick film DLC-coated member according to claim 1, wherein the post-heat treatment thick film DLC is a film to be processed whose surface is irradiated with a laser beam heat source or an electron beam heat source. 3. The thick film DLC-coated member according to claim 1, wherein the base material is an inorganic compound or a nonmetallic organic compound that is either metal or nonmetal. A thick film having an initial residual stress of less than 1.0 GPa formed of a deposition layer of ultrafine particles having a film thickness of more than 3 μm, hydrogen of 13 to 30 atomic% and the balance of carbon, which is formed on the surface of the substrate by a plasma CVD method DLC
By subjecting the one having an initial residual stress of less than 1.0 GPa to a heat treatment for 0.1 to 30 hours at a temperature not lower than the film forming temperature and not higher than 550 ° C.,
A method for producing a thick film DLC-coated member, characterized by forming a heat-treated DLC film having a residual stress of 1.0 GPa or more and a hardness (Hv) of 700 to 2800. 5. The thick film DLC covering member according to claim 4 , wherein the heat treatment of the thick film DLC is performed in one or more atmospheres selected from oxygen gas, air, inert gas, and vacuum. Manufacturing method. 6. The method for manufacturing a thick film DLC-coated member according to claim 4, wherein the post-heat treatment thick film DLC has a surface to be processed that is irradiated with a laser beam heat source or an electron beam heat source.

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