JP2009185373A - Manufacturing method of hard material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for manufacturing a hard material more easily as compared with the conventional art. <P>SOLUTION: The hard material is produced by using a plasma-enhanced chemical vapor deposition method by pulse discharge, and subjecting the oxide of at least one of elements selected from B, Ti, W, and Si to hydrogen reduction, then to nitriding, carbonizing or carbonitriding. It is preferable that one or two or more selected from B<SB>2</SB>O<SB>3</SB>, TiO, TiO<SB>2</SB>, Ti<SB>2</SB>O<SB>3</SB>, WO<SB>2</SB>, W<SB>2</SB>O<SB>5</SB>, WO<SB>3</SB>, SiO<SB>2</SB>are included in the oxide. Also, the hard material obtained by using the manufacturing method is used as a coating material for a cutting tool. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a hard substance.

  In order to improve wear resistance, durability, and corrosion resistance of cutting tools, molds, machine parts, and the like, it is widely performed to coat hard surfaces thereof. As such a coating material, for example, a nitride such as TiN or a carbide such as TiC, WC, or SiC is often used. In recent years, c-BN (cubic boron nitride) having the second highest hardness after diamond is also expected to be applied to coating materials.

  These nitride and carbide manufacturing technologies include PVD (physical vapor deposition) methods such as ion plating, sputtering, and electron beam vapor deposition, and CVD (chemical vapor deposition) such as plasma CVD and thermal CVD. ) Laws are known.

For example, Non-Patent Document 1 discloses a method of synthesizing TiN by evaporating and ionizing titanium using an arc discharge or an electron gun, and causing titanium ions and nitrogen ions to collide with and react with a substrate surface (ion plating method). ), A method of synthesizing TiC or TiN by bringing a volatile metal compound salt (TiCl ₄ ) vaporized at a low temperature and a reaction gas (CH ₄ or N ₂ ) into contact with the substrate surface heated to a high temperature and reacting them. (CVD method) describes a method (electron beam evaporation method) in which boron is vapor-deposited by an electron beam and a mixed gas of nitrogen and argon is ionized by an ion gun to synthesize c-BN.

Patent Document 1 discloses that a c-BN thin film is formed at a substrate temperature of 350 to 650 ° C. using an Ar—N ₂ mixed gas by a high frequency bias sputtering method using h-BN (hexagonal boron nitride) as a target. Techniques for synthesizing are disclosed.

Further, in Patent Document 2, argon and hydrogen gas are used for plasma control, and boron source BF ₃ gas and nitrogen gas are reacted using plasma to synthesize a c-BN thin film on a silicon substrate from the gas phase. A method is disclosed.

Masaru Ikenaga and Hideto Suzuki “Principle and industrial application of ultra-hard coating by dry process”, Nikkan Kogyo Shimbun, pp. 6-31, (2000) Japanese Patent Laid-Open No. 11-12717 JP 2001-302218 A

  However, the conventional method for producing a hard material has the following problems.

  In other words, boron, titanium, and the like often exist in nature as oxides, and these oxides are stable, so that it is difficult to decompose them using plasma or the like.

Therefore, for example, when c-BN is synthesized using the above-described conventional PVD method, boron alone obtained by refining borate (B (OH) ₃ ) or the like by electrolytic reduction is used as a raw material. There was a problem that it had to be used and a great deal of effort had to be spent to obtain the final product.

Further, even when c-BN or TiN is synthesized using the conventional CVD method, boron or titanium oxide cannot be used as a raw material as it is, and halogen such as BF ₃ gas is used as a source gas. metal compound salt such as halides or TiCl _4, must be used, such as organic compounds, in addition to the above problems, environmental load was also concern that such according to the use of harmful gases.

  Then, the subject which this invention tends to solve is providing the manufacturing method which can manufacture a hard substance simply compared with the past.

  As a result of intensive research by the present inventors, using a plasma chemical vapor deposition method by pulse discharge, an oxide is reduced using a very high reducing atmosphere by hydrogen radicals, which is a feature of this method, It has been found that it can be carbonized or carbonitrided.

  The present invention has been made mainly based on the above knowledge, and the method for producing a hard material according to the present invention is at least selected from B, Ti, W and Si using a plasma chemical vapor deposition method by pulse discharge. The gist of the invention is to have a step of hydrogen reduction of an oxide of one element and nitriding, carbonizing or carbonitriding.

Here, the oxide may include one or more selected from B ₂ O ₃ , TiO, TiO ₂ , Ti ₂ O ₃ , WO ₂ , W ₂ O ₅ , WO ₃ , and SiO _2. .

  Then, hydrogen gas is used as the reaction gas. Further, when producing nitride, nitrogen-containing gas, when producing carbide, carbon-containing gas, when producing carbonitride, nitrogen-containing gas and carbon It is preferable to use a contained gas.

  Further, the oxide may be formed in a thin film shape.

  In this case, the thickness of the oxide is preferably in the range of 1 nm to 100 μm.

The pulse discharge is performed at least with a gas pressure of 1 to 800 Torr, a discharge current density of 0.001 to 1000 A / cm ² , a discharge time of 0.01 to 10 ms in each cycle of the pulse, and a discharge stop time of 0.01 to 10 ms. It is good to meet the conditions.

  Furthermore, the gist of the present invention is to use a hard material obtained by the above-described manufacturing method as a coating material.

  In the production method according to the present invention, an extremely high reducing atmosphere by hydrogen radicals is used, so that an oxide can be used as a raw material, and the oxide can be directly reduced and nitrided, carbonized or carbonitrided. Therefore, it is possible to produce a hard substance more easily than in the past.

Further, in the conventional PVD method, the pressure in the reaction vessel at the time of production needs to be a high vacuum of 10 ⁻⁴ Torr or less, but in the production method according to the present invention, the pressure of the preliminary exhaust in the reaction vessel is A vacuum of about 10 ⁻² Torr is sufficient, and the pressure during pulse discharge may be about 1 to 800 Torr and does not require a high vacuum.

  Furthermore, since direct current (DC) plasma discharge can be used, the apparatus is less expensive than radio frequency (RF) sputtering.

In addition, relatively inexpensive B ₂ O ₃ , TiO, TiO ₂ , Ti ₂ O ₃ , WO ₂ , W ₂ O ₅ , WO ₃ , and SiO ₂ can be used as raw materials for oxides, thereby reducing manufacturing costs. be able to.

  And in the manufacturing method which concerns on this invention, the gas which does not contain harmful gas, such as a halogen, can be used as a reactive gas, and an environmental load can be suppressed.

  In addition, in the manufacturing method according to the present invention, an oxide formed in a thin film shape can be used, and if the film thickness is in the range of 1 nm to 100 μm, the thin film is sufficiently reduced to be nitrided, carbonized or It can be carbonitrided.

Further, the pulse discharge is performed at least at a gas pressure of 1 to 800 Torr, a discharge current density of 0.001 to 1000 A / cm ² , a discharge time of 0.01 to 10 ms in each cycle of the pulse, and a discharge stop time of 0.01 to 10 ms. If the conditions are satisfied, the oxide can be efficiently reduced and nitrided, carbonized, or carbonitrided.

  In addition, since the tool according to the present invention uses the hard material obtained by the above manufacturing method as a coating material, it has excellent mechanical properties such as wear resistance, contributes to the extension of the tool life, and suppresses the manufacturing cost. be able to.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, a hard substance is manufactured using an oxide of a specific element as a raw material using a plasma chemical vapor deposition method by pulse discharge.

Specifically, an oxide of at least one element selected from B, Ti, W, and Si is used. Preferably, one or more oxides selected from B ₂ O ₃ , TiO, TiO ₂ , Ti ₂ O ₃ , WO ₂ , W ₂ O ₅ , WO ₃ , and SiO ₂ may be used. Among these, B ₂ O ₃ is more preferably used. This is because B ₂ O ₃ can be produced by a simple method as described later, and the material cost is relatively low.

  And a hard substance can be manufactured by reduce | restoring the said oxide using a reactive gas, and nitriding, carbonizing, or carbonitriding.

  Hydrogen gas is used as the reaction gas for reducing the oxide. Furthermore, in addition to the above hydrogen gas, when producing a nitride, an oxide can be nitrided using a nitrogen-containing gas.

  Examples of the nitrogen-containing gas include ammonia gas in addition to nitrogen gas, but are not necessarily limited thereto.

  In the case of producing a carbide, the oxide can be carbonized using a carbon-containing gas in addition to the hydrogen gas.

  Examples of the carbon-containing gas include hydrocarbon gases such as methane gas, propane gas, acetylene gas, and benzene gas, methyl alcohol gas, and ethyl alcohol gas, but are not necessarily limited thereto. Moreover, the said hydrocarbon gas may be 1 type, or 2 or more types may be mixed.

  Furthermore, when producing carbonitrides, oxides can be carbonitrided using the nitrogen-containing gas and carbon-containing gas shown above in addition to the hydrogen gas.

  The oxide may be in the form of a thin film, a bulk, a powder, or the like, but preferably the oxide is formed in a thin film. This is because if it is in the form of a thin film, it is possible to easily coat the surface of cutting tools, molds, machine parts, and the like.

  When using a thin film-like oxide, this film thickness is preferably in the range of 1 nm to 100 μm. If the thickness of the oxide is within this range, the oxide can be sufficiently reduced and nitrided, carbonized or carbonitrided. In addition, within this range, the wear resistance, durability, and corrosion resistance can be sufficiently enhanced when used for coating a surface of a cutting tool, a die, a machine part, or the like.

  The method for manufacturing the thin film oxide is not particularly limited, but it is preferable to use a non-vacuum process capable of forming a thin film relatively easily without requiring an expensive apparatus.

For example, thin-film B ₂ O ₃ can be obtained by applying an aqueous boric acid solution to the substrate surface and heat-treating it. Boric acid (H ₃ BO ₃ ) is known to reach the decomposition point at an atmospheric pressure of 171 degrees and form boric anhydride (B ₂ O ₃ ), and this process can be used.

The thin-film-like _{TiO 2, WO 2, W 2} O 5, WO 3, SiO 2 , for example, can be formed by using a sol-gel method.

  In the case of forming by the sol-gel method, the metal alkoxide as the raw material specifically includes, for example, at least one M—O—C (M: represents metal, O: oxygen, C: represents carbon) bond. Examples thereof include metal organic compounds in which H of alcohol R—O—H is substituted with metal. Hereinafter, metal alkoxides are illustrated more specifically, but are not necessarily limited thereto. Moreover, these can also be used 1 type or in mixture of 2 or more types.

  Specific examples of the titanium-based alkoxide include titanium tetraisopropoxide, titanium tetraethoxide, titanium tetrabutoxide, and cyclopentadinier titanium triisopropoxide.

  Specific examples of the tungsten alkoxide include tungsten pentaethoxide.

  Specific examples of the silicon alkoxide include methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate, phenyltriethoxysilane, allyltriethoxysilane, methyltriethoxysilane, and cyclopentyltriethoxysilane. .

  The sol-gel method may be performed by diluting the metal alkoxide with a solvent such as toluene or dichloroethylene to prepare a coating solution, and coating the coating solution on the substrate in the air. In this case, specific examples of the coating method on the substrate include a dipping method, a spraying method, a spin coating method, and a simple brush coating method. What is necessary is just to select suitably considering the shape of a base material, a target film thickness, etc. And the sample coated on the base material can be heat-treated to obtain a thin film-like oxide.

As the bulk oxide, a sintered body of B ₂ O ₃ , TiO, TiO ₂ , Ti ₂ O ₃ , WO ₂ , W ₂ O ₅ , WO ₃ , and SiO ₂ can be used. The sintered body can be manufactured using a solid phase reaction method or the like.

  In addition to the above manufacturing method, a vacuum technique can be used for the manufacturing method of the thin film-like oxide. For example, a PVD (physical vapor deposition) method such as an ion plating method, a sputtering method, or an electron beam vapor deposition method, or a CVD (chemical vapor deposition) method such as a plasma CVD method or a thermal CVD method can be used. By using these methods, a thin-film oxide having a smooth surface can be obtained.

  The oxide obtained as described above is subjected to hydrogen reduction, nitriding, carbonizing, or carbonitriding using a plasma chemical vapor deposition method by pulse discharge to produce a hard substance.

  Next, an example of the manufacturing method of the hard substance according to the present invention will be described more specifically with reference to the drawings. FIG. 1 is a schematic view of a plasma chemical vapor deposition apparatus using pulse discharge, which is preferably used in the method for producing a hard material of the present invention. The plasma chemical vapor deposition apparatus 50 by pulse discharge includes a reaction chamber 10, an exhaust valve 12, a vacuum pump 14, a reaction gas introduction valve 16, a mass flow controller 18, a reaction gas 20, a pulse power source 22, and a cathode 24.

  The vacuum pump 14 is connected to the reaction chamber 10 via the exhaust valve 12 and is used to evacuate the reaction chamber 10. The mass flow controller 18 is connected to the reaction chamber 10 via the reaction gas introduction valve 16 and adjusts the flow rate of the gas introduced into the reaction chamber 10. The pulse power source 22 is connected to the cathode 24 disposed in the reaction chamber 10 via the reaction chamber 10 and causes discharge between the cathode 24 and the substrate. In order to prevent an excessive temperature rise of the base material, a water cooling table (not shown) is provided around the holder.

  FIG. 2 is a schematic diagram of the configuration of the pulse power supply. The pulse power source 22 is a DC power source 26, an intelligent power module (IPM) 28 that interrupts its output, a pulse transmitter 30, a resistor 32, and a current that is interrupted on the low-voltage side to generate a high voltage required for discharge on the high-voltage side. A high voltage transformer 34 and a diode 36 for discharging the voltage from the high voltage side of the high voltage transformer are provided.

  In this pulse power source 22, the output of the DC power source 26 whose output voltage can be changed from 0 to about 200 V is intermittently transmitted by the intelligent power module 28 using a pulse transmitted from the pulse transmitter 30, while the high voltage transformer In addition to the low voltage side of 34, the ON and OFF times when the current is interrupted can be changed in a wide range by the pulse transmitter 30. The pulse power supply 22 uses a large inductance of the high-voltage transformer 34 and a transient phenomenon caused by the resistor 32 inserted in the circuit to suppress a sudden increase in current that causes arc discharge. The voltage on the high voltage side of the transformer 34 is applied to the discharge electrode through the diode 36 and can be discharged.

  FIG. 3 is a graph illustrating waveforms during discharge. (A) is a waveform of a pulse transmitter, (b) is a waveform of a discharge voltage between electrodes, and (c) is a waveform of a discharge current. Here, Ip is the discharge current, Td is the discharge time, Tn is the discharge stop time, Vp is the peak voltage at the start of discharge, Vg is the discharge voltage, Ta is the time until the current becomes zero after the discharge stops, Tr is the pulse This is the rise time of the pulse voltage from when the discharge voltage reaches the discharge start voltage.

First, after an oxide sample is introduced into the reaction chamber 10, the exhaust valve 12 is opened, and the vacuum pump 14 starts evacuating the reaction chamber 10. After evacuating until the degree of vacuum in the reaction chamber 10 becomes about 10 ⁻² Torr, the reaction gas introduction valve 16 is opened, and the reaction gas 20 having a flow rate set by the mass flow controller 18 is introduced into the reaction chamber 10. Thereafter, a voltage is generated from the pulse power source 22 to cause a discharge between the cathode and the base material, thereby nitriding, carbonizing or carbonitriding the oxide.

  At this time, the introduction procedure of each reaction gas is not particularly limited. For example, the oxide can be reduced with hydrogen and simultaneously or subsequently nitrided, carbonized, carbonitrided. Specifically, in the case of producing nitride, hydrogen gas and nitrogen-containing gas may be simultaneously introduced into the reaction chamber 10 to perform reduction and nitridation at the same time. After the oxide sample is reduced to some extent by introduction into the gas, a nitrogen-containing gas may be further introduced and nitrided. Alternatively, after hydrogen gas is first introduced into the reaction chamber 10 to reduce the oxide sample, only the nitrogen-containing gas may be introduced into the reaction chamber 10 for nitriding.

  In the case of producing carbide, hydrogen gas and carbon-containing gas may be simultaneously introduced into the reaction chamber 10 to perform reduction and carbonization at the same time, or hydrogen gas may be introduced into the reaction chamber 10 first to oxidize. After the product sample is reduced to some extent, a carbon-containing gas may be further introduced and carbonized. Alternatively, after hydrogen gas is first introduced into the reaction chamber 10 to reduce the oxide sample, only the carbon-containing gas may be introduced into the reaction chamber 10 to be carbonized.

  When carbonitride is produced, hydrogen gas, nitrogen-containing gas, and carbon-containing gas may be simultaneously introduced into the reaction chamber 10 to perform reduction and carbonitriding at the same time. After introducing the sample 10 into the oxide sample and reducing the oxide sample to some extent, a nitrogen-containing gas and a carbon-containing gas may be further introduced and carbonitrided. Alternatively, after hydrogen gas is first introduced into the reaction chamber 10 to reduce the oxide sample, only the nitrogen-containing gas and the carbon-containing gas may be introduced into the reaction chamber 10 for carbonitriding.

  In addition to the reaction gas, an inert gas such as argon may be used for adjusting the pressure in the reaction chamber. The mixing ratio of these gases is not particularly limited, and can be changed as appropriate.

  As a condition for the pulse discharge, the gas pressure in the reaction chamber is preferably in the range of 1 to 800 Torr. More preferably, it is 1-50 Torr, More preferably, it is 10-50 Torr. This is because if the gas pressure is 1 Torr or more, the number of ions in the reaction chamber can be kept moderate, and the discharge is stabilized. Further, when the gas pressure is 800 Torr or less, an appropriate discharge region can be maintained without extremely shortening the mean free path of ions, and the oxide is efficiently reduced by hydrogen to be nitrided, carbonized or carbonitrided. Because it can.

If the discharge current density is increased, the film formation rate can be increased. However, it is preferable that the discharge current density is set to a value corresponding to the purpose in consideration of the heating / melting of the sample by the plasma and the power source capacity. Specifically, the discharge current density is preferably in the range of 0.001 to 1000 A / cm ² . More preferably from 0.01 to 100 A / cm ^2, more preferably from 0.1 to 10 A / cm ^2. This is because, if the discharge current density is 0.001 A / cm ² or more, ions can be appropriately collided with the sample. Moreover, if it is 1000 A / cm < ² > or less, it is because the damage of the surface of an oxide sample can be suppressed, without ion collision energy increasing extremely.

  The discharge time, discharge stop time, interelectrode distance, and the like in each cycle of the pulse are preferably set so that stable discharge can be sustained and nitriding, carbonizing, and carbonitriding can be performed efficiently.

  Specifically, the discharge time in each cycle of the pulse is preferably in the range of 0.01 to 10 ms. More preferably, it is 0.1-10 ms, More preferably, it is 0.5-10 ms. This is because if the discharge time in each cycle of the pulse is 0.01 ms or more, the sample can be efficiently reduced by hydrogen and nitrided, carbonized or carbonitrided. Moreover, if it is 10 ms or less, the discharge is less likely to become an arc, and the discharge can be more stabilized.

  Considering the fact that the lifetime of ions and electrons other than hydrogen is 100 μs and the lifetime of atomic hydrogen (hydrogen radical) is about 3 ms, the discharge stop time can secure the reduction action time by this atomic hydrogen. It only has to be within the range. Specifically, the discharge stop time is preferably in the range of 0.01 to 10 ms. More preferably, it is 1-10 ms, More preferably, it is 2-10 ms. If the discharge stop time is 0.01 ms or longer, the next pulse is not generated before the discharge voltage returns to the steady state, and it is possible to suppress the discharge from becoming an arc, and the discharge becomes more stable. is there. Moreover, if the discharge stop time is 10 ms or less, an appropriate frequency can be obtained, and the sample can be efficiently reduced by hydrogen and nitrided, carbonized or carbonitrided.

  The inter-electrode distance d can be appropriately changed depending on the electrode shape, the size of the reaction chamber, the shape of the sample, etc., but is preferably in the range of 5 to 50 mm. This is because if the inter-electrode distance d is 5 mm or more, the entire sample can be processed without unevenness. Further, when the inter-electrode distance d is 50 mm or less, a stable discharge can be obtained without generating a discharge in another place.

  The discharge treatment time for reducing the sample to hydrogen and nitriding, carbonizing, or carbonitriding is not particularly limited, and can be appropriately changed according to the shape of the sample. Also, the duty ratio obtained by dividing the discharge voltage and the discharge time in each cycle of the pulse by the discharge stop time can be changed as appropriate according to the above conditions and the like.

  The tool according to this embodiment uses a hard material manufactured by the above-described method as a coating material. As a method of coating the tool with a hard substance, for example, a method of forming the above-described thin film-like oxide on the substrate surface can be used.

  First, a boric acid aqueous solution or a coating solution obtained by diluting a metal alkoxide with a solvent such as toluene or dichloroethylene is applied to the tool surface by a method such as dipping, spraying, spin coating, or simple brush coating. Then, using a plasma chemical vapor deposition method using pulse discharge, the oxide formed on the tool surface can be reduced with hydrogen, nitrided, carbonized or carbonitrided, and coated with a hard material.

  As mentioned above, although the manufacturing method of the hard substance which concerns on this embodiment, a hard substance, and the tool using this were demonstrated, the said embodiment does not limit this invention at all, and various in the range which does not deviate from the meaning. It can be modified and improved.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited by these.

(Example 1)
An aqueous boric acid solution (concentration: 10%) obtained by dissolving boric acid (H ₃ BO ₃ ) in water is applied onto a SUS304 “20 × 20 mm, thickness 0.75 mm” base material with a dropper, and air is applied using a hot plate. It was heat-treated at 100 degrees.

Then, the above-mentioned sample was measured with a distance d between the electrodes of 25 mm, a mixed gas ratio of H ₂ / N ₂ = 1/2, an inflow gas amount of 30 cc / min, a discharge gas pressure of 38 Torr, a discharge voltage of 650 V, and a discharge current of 4 A. A hard substance was manufactured by performing hydrogen reduction and nitriding treatment by a plasma chemical vapor deposition method using pulse discharge with a frequency of 1205 Hz, a duty ratio of 10%, and a discharge time of 60 min. In addition, the sample was placed at a position away from the water-cooled table and processed so as to reach the decomposition point temperature of boric acid during discharge.

FIG. 4A shows the measurement result of the X-ray diffraction of the sample processed in Example 1. FIG. For comparison, FIG. 4 (b) also shows the H ₃ BO ₃ before discharge applied on the SUS304 base material, and FIG. 4 (c) also shows the X-ray diffraction measurement results of the SUS304 base material alone. Show.

In H ₃ BO ₃ before discharge applied on the SUS304 base material, only peaks of H ₃ BO ₃ and SUS304 can be confirmed from FIG. 4B. In contrast, the c-BN peak can be confirmed in the sample processed in Example 1 from FIG. Moreover, although the peak of B can be confirmed slightly, the peak of H ₃ BO ₃ is hardly confirmed.

Further, when sample analysis was performed on the sample processed in Example 1, c-BN and B were slightly confirmed. The sample obtained in Example 1 was a hard film that could not be scraped off. Furthermore, it was confirmed that the H ₃ BO ₃ applied on the SUS304 base material before discharge was white, whereas the sample treated in Example 1 was discolored to black peculiar to B.

(Example 2)
TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, and hydrogen reduction and nitridation were performed by plasma chemical vapor deposition using pulse discharge. Processing was performed to produce a hard material.

Discharge conditions were: electrode distance d 25 mm, mixed gas ratio H ₂ / N ₂ = 1/2, inflow gas amount 30 cc / min, discharge gas pressure 38 Torr, discharge voltage 650 V, frequency 1205 Hz, duty ratio Was 20%, the discharge time was 90 min, and the discharge current was 4A and 2A.

FIG. 5A shows the measurement result of the X-ray diffraction of the sample treated with the discharge current 4A, and FIG. 5B shows the sample treated with the discharge current 2A. For comparison, FIG. 5C also shows the measurement result of the X-ray diffraction of the TiO ₂ sintered body before discharge.

It can be seen from FIG. 5C that the TiO ₂ sintered body before discharge has a rutile structure. On the other hand, in the sample treated with the discharge current 4A, a strong peak of TiN can be confirmed from FIG. Further, in the sample treated with the discharge current 2A, the peak of TiN can be confirmed from FIG. Further, it was confirmed that the TiO ₂ sintered body before discharge was white, whereas the samples treated with the discharge currents 4A and 2A were discolored to a gold color peculiar to TiN.

(Example 3)
A TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, the inter-electrode distance d was 25 mm, and the mixed gas ratio was H ₂ / N. ₂ = 1/2, inflow gas amount is 30cc / min, discharge gas pressure is 38 Torr, discharge voltage is 600V, frequency is 1205Hz, duty ratio is 10%, discharge time is 180min, discharge current is 2A The material was manufactured.

Example 4
A TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, the inter-electrode distance d was 25 mm, and the mixed gas ratio was H ₂ / N. ₂ = 1/2, inflow gas amount is 30cc / min, discharge gas pressure is 38 Torr, discharge voltage is 600V, frequency is 1538Hz, duty ratio is 10%, discharge time is 180min, discharge current is 2A The material was manufactured.

(Example 5)
A TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, the inter-electrode distance d was 25 mm, and the mixed gas ratio was H ₂ / N. ₂ = 1/2, inflow gas amount is 30cc / min, discharge gas pressure is 38 Torr, discharge voltage is 600V, frequency is 1205Hz, duty ratio is 10%, discharge time is 90min, discharge current is 2A The material was manufactured.

(Comparative Example 1)
A TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, the reaction gas was only H _2, and the inter-electrode distance d was 25 mm. Discharging was performed under the conditions of an inflow gas amount of 30 cc / min, a discharge gas pressure of 38 Torr, a discharge voltage of 600 V, a frequency of 1205 Hz, a duty ratio of 10%, a discharge time of 180 min, and a discharge current of 2 A.

(Comparative Example 2)
A TiO ₂ sintered body (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%, diameter 10 mm, thickness 5 mm) was used as the oxide sample, the reaction gas was N ₂ only, and the interelectrode distance d was 25 mm. Discharging was performed under the conditions of an inflow gas amount of 30 cc / min, a discharge gas pressure of 38 Torr, a discharge voltage of 600 V, a frequency of 1205 Hz, a duty ratio of 10%, a discharge time of 180 min, and a discharge current of 2 A.

In FIG. 6, the measurement result of the X-ray diffraction of the sample obtained in Examples 3-5 and Comparative Examples 1 and 2 is shown. For comparison, the X-ray diffraction data of the TiO ₂ sintered body before discharge measured in Example 2 is also shown.

From FIG. 6, Examples 3-5 can confirm the peak of TiN. On the other hand, no peak of TiN was confirmed in Comparative Example 1 treated using only H ₂ as the reactive gas and Comparative Example 2 treated using only N _{2 as} the reactive gas. In Comparative Example 1, the sample was not nitrided because only H ₂ was used as the reaction gas. In Comparative Example 2, it was assumed that the sample was not sufficiently reduced because only N ₂ was used as the reaction gas. Is done. In Comparative Example 2, a peak of β-W ₂ N is confirmed, which is presumed to be that W used for the electrode is partly plasmatized and reacted with N ₂ .

  As described above, from the results of Examples 1 to 5 and Comparative Examples 1 and 2, it is possible to produce a hard material by reducing the oxide with hydrogen using a plasma chemical vapor deposition method by pulse discharge and nitriding. It could be confirmed.

It is the schematic which showed the structure of the plasma chemical vapor deposition apparatus by pulse discharge. It is the schematic of the power supply circuit used for the plasma chemical vapor deposition apparatus by pulse discharge. It is the graph which illustrated the waveform of (a) pulse transmitter, (b) waveform of discharge voltage between electrodes, and (c) waveform of discharge current at the time of performing discharge with the plasma chemical vapor deposition apparatus by pulse discharge. . Example a 1 X-ray diffraction pattern, (a) shows the X-ray diffraction pattern of a sample treated in this Example 1, (b) is before arc coated on SUS304 substrate of H ₃ BO ₃ X-ray diffraction pattern, (c) is an X-ray diffraction pattern of SUS304 base material only. It is an X-ray diffraction pattern of Example 2, (a) is an X-ray diffraction pattern of a sample treated with a discharge current 4A, (b) is an X-ray diffraction pattern of a sample treated with a discharge current 2A, (c). Is an X-ray diffraction pattern of a TiO ₂ sintered body before discharge. 3 is an X-ray diffraction pattern of samples obtained in Examples 3 to 5 and Comparative Examples 1 and 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Reaction chamber 12 ... Exhaust valve 14 ... Vacuum pump 16 ... Reaction gas introduction valve 18 ... Mass flow controller 20 ... Reaction gas 22 ... Pulse power supply 24 ... Cathode 26 ... DC power supply 28 ... Intelligent power module (IPM)
30 ... Pulse transmitter 32 ... Resistor 34 ... High voltage transformer 36 ... Diode 50 ... Plasma chemical vapor deposition apparatus by pulse discharge

Claims (7)

  Using a plasma chemical vapor deposition method using pulse discharge, the method includes hydrogen-reducing and nitriding, carbonizing, or carbonitriding an oxide of at least one element selected from B, Ti, W, and Si. A manufacturing method of a hard substance. The oxide includes one or more selected from B ₂ O ₃ , TiO, TiO ₂ , Ti ₂ O ₃ , WO ₂ , W ₂ O ₅ , WO ₃ and SiO _2. The manufacturing method of the hard substance of Claim 1. Hydrogen gas is used as the reaction gas,
Furthermore, a nitrogen-containing gas is used when producing nitride, a carbon-containing gas is used when producing carbide, and a nitrogen-containing gas and a carbon-containing gas are used when producing carbonitride. 3. A method for producing a hard substance according to 1 or 2.   The said oxide is formed in thin film form, The manufacturing method of the hard substance in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a hard substance according to claim 4, wherein the oxide has a thickness in a range of 1 nm to 100 µm. The pulse discharge has at least discharge conditions of a gas pressure of 1 to 800 Torr, a discharge current density of 0.001 to 1000 A / cm ² , a discharge time of 0.01 to 10 ms in each cycle of the pulse, and a discharge stop time of 0.01 to 10 ms. The method for producing a hard material according to claim 1, wherein the hard material is satisfied.   A tool using a hard substance obtained by the manufacturing method according to claim 1 as a coating material.

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