WO2022014709A1

WO2022014709A1 - Metal carbide film-coated member and method for producing same

Info

Publication number: WO2022014709A1
Application number: PCT/JP2021/026851
Authority: WO
Inventors: 智羽深; 宏之松岡
Original assignee: Ｄｏｗａサーモテック株式会社
Priority date: 2020-07-16
Filing date: 2021-07-16
Publication date: 2022-01-20
Also published as: JP2022019697A

Abstract

This metal carbide film-coated member has a steel material having a carbide layer at the surface and has, on the carbide layer, a metal carbide film that contains carbon and at least one metal selected from the group consisting of V, Ti, Al, Cr, Nb, and Si, wherein, defining the ratio between the maximum x-ray diffraction peak intensity [carbide intensity] originating with the metal carbide of the steel material and the maximum x-ray diffraction peak intensity [Fe intensity] originating with α-Fe, the peak intensity ratio for the carbide layer [carbide intensity/Fe intensity] is 0.5-4.0.

Description

Metal carbide film covering member and its manufacturing method

The present invention relates to a metal carbide film covering member in which a metal carbide film is formed on a steel material, and a method for manufacturing the same.

Conventionally, in press forming dies, cutting tools, gear cutting tools, forging tools, etc., a hard film is coated on the steel material to prevent damage due to contact friction with the material to be molded and contact friction with the mating material of the tool. It is known to do. For example, Patent Document 1 contains vanadium and carbon such as vanadium carbide film (VC film) and vanadium nitride film (VCN film), which are rich in lubricity on steel materials of cutting tools, gear cutting tools or forging tools. It is disclosed to coat the membrane. Patent Document 2 discloses that a titanium carbide film (TiC) is coated on a steel material such as a mold and a tool.

Japanese Patent Application Publication No. 2005-046975 Japanese Patent Application Publication No. 2014-015636

According to the study by the present inventors, the metal carbide film covering member in which the metal carbide film containing metal and carbon such as vanadium and titanium is directly formed on the surface of the steel material is the steel material and the metal carbide in the Rockwell indentation test. It was found that the adhesion to the membrane was low. Therefore, it is desired to improve the adhesion between the steel material and the metal carbide film in order to improve the performance as the metal carbide film covering member.

The present invention has been made in view of the above circumstances, and is a metal carbide film coating member capable of improving the adhesion between the steel material and the metal carbide film in the Rockwell indentation test of the metal carbide film coating member, and a method for manufacturing the same. The purpose is to provide.

As a result of intensive research to solve the above problems, the present inventor has applied a metal carbide film on a specific carbide layer formed on the surface of a steel material to perform a rockwell indentation test on a metal carbide film covering member. The present invention has been completed by finding that the adhesion in the above-mentioned is improved and thereby the above-mentioned object is achieved.

The present invention that solves the above problems will be exemplified below.
[1] A metal carbide film covering member, which is a member.
Steel materials with a carbide layer on the surface and
The carbide layer comprises one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si and a metal carbide film containing carbon.
The ratio of the maximum peak intensity [carbide strength] of X-ray diffraction derived from metal carbides of steel materials to the maximum peak intensity [Fe intensity] of X-ray diffraction derived from α-Fe is the peak intensity ratio [carbide strength / Fe strength]. ], The peak intensity ratio of the carbide layer is 0.5 to 4.0.
[2] In the metal carbide film covering member according to [1],
The peak intensity ratio of the carbide layer is 2.0 or less.
[3] In the metal carbide film covering member according to [1],
The peak intensity ratio of the carbide layer is 1.0 or less.
[4] In the metal carbide film covering member according to [1],
The metal carbide film is a silica carbide vanadium film containing vanadium, silicon, and carbon.
In the silica carbide vanadium film, the total of the vanadium element concentration, the silicon element concentration, and the carbon element concentration in the film is 90 at% or more.
[5] In the metal carbide film covering member according to [4],
The vanadium element concentration in the silica carbide vanadium film is 8 to 30 at%, the silicon element concentration is 8 to 30 at%, and the carbon element concentration is 40 to 80 at%.
[6] A method for manufacturing a metal carbide film covering member.
A plasma carbide treatment process that forms a carbide layer on the surface of the steel material,
It has a metal carbide film forming step of forming a metal carbide film containing carbon and one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si on the carbide layer.
The ratio of the maximum peak intensity [carbide strength] of X-ray diffraction derived from metal carbides of steel materials to the maximum peak intensity [Fe intensity] of X-ray diffraction derived from α-Fe is the peak intensity ratio [carbide strength / Fe strength]. ], In the plasma carbide treatment step, the carbide layer is formed so that the peak intensity ratio of the carbide layer after the plasma carbide treatment step is 0.5 to 4.0.
[7] In the method for manufacturing a metal carbide film covering member according to [6],
In the plasma carbonization treatment step, the carbide layer is provided so that [the peak intensity ratio of the steel material after the plasma carbonization treatment step / the peak intensity ratio of the steel material before the plasma carbonization treatment step] satisfies 2.4 to 19. Form.
[8] A method for manufacturing a metal carbide film covering member.
A plasma carbide treatment process that forms a carbide layer on the surface of the steel material,
It has a metal carbide film forming step of forming a metal carbide film containing carbon and one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si on the carbide layer.
The plasma carbonization treatment step is performed in an atmosphere in which a carbon source gas supplied as a treatment gas and a hydrogen gas are converted into plasma.
[9] In the method for manufacturing a metal carbide film covering member according to [8],
The carbon source gas flow rate / hydrogen gas flow rate, which is the flow rate ratio of the carbon source gas to the hydrogen gas, is 0.01 to 0.40.
[10] In the method for manufacturing a metal carbide film covering member according to [9],
When hydrogen gas, carbon source gas and argon gas are supplied as the processing gas in the plasma carbonization treatment step and the volumetric flow rate of the hydrogen gas is 1, the ratio of the volumetric flow rate of hydrogen gas: carbon source gas: argon gas is It is 1: 0.01 to 0.40: 0.01 to 0.10.
[11] In the method for manufacturing a metal carbide film covering member according to [8],
The carbon source gas is methane gas.
[12] In the method for manufacturing a metal carbide film covering member according to [6],
The metal carbide film is a silica carbide vanadium film containing vanadium, silicon, and carbon.
In the silica carbide vanadium film, the total of the vanadium element concentration, the silicon element concentration, and the carbon element concentration in the film is 90 at% or more.
[13] In the method for manufacturing a metal carbide film covering member according to [12],
The vanadium element concentration in the silica carbide vanadium film is 8 to 30 at%, the silicon element concentration is 8 to 30 at%, and the carbon element concentration is 40 to 80 at%.

The symbol "-" used in the expression of the numerical range in the present specification indicates a range of a predetermined numerical value or more and a predetermined numerical value or less.

According to the present invention, it is possible to improve the adhesion between the steel material and the metal carbide film in the rockwell indentation test of the metal carbide film covering member.

It is a figure which shows the schematic structure of the metal carbide film covering member which concerns on one Embodiment of this invention. It is a figure which shows an example of a plasma processing apparatus. It is a figure which shows the shape of a test piece. It is a figure which shows the X-ray diffraction analysis result of the test piece surface before the plasma carbonization treatment process, and the test piece surface after the plasma carbonization treatment process. It is a figure which shows the rockwell indentation test result of Example 1. FIG. It is a figure which shows the rockwell indentation test result of Example 2. It is a figure which shows the rockwell indentation test result of Example 3. FIG. It is a figure which shows the rockwell indentation test result of the comparative example 1. FIG. It is an electron microscope image which shows the cross section of the sample of Example 1. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present specification and the drawings, the elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

As shown in FIG. 1, the metal carbide film covering member 1 of the present embodiment is composed of a steel material 2 having a carbide layer 2a formed on its surface and a metal carbide film 3 directly formed on the carbide layer 2a of the steel material 2. ing.

<Steel material>
The steel grade of the steel material is not particularly limited, and a steel grade suitable for the application of the metal carbide film covering member 1 may be used. Examples of the steel type include high-speed tool steel (high-speed steel) such as SKH51, so-called cold tool steel such as SKD11 and DC53 trade name manufactured by Daido Special Steel Co., Ltd., or cold die steel (cold die steel). Etc. can be adopted.

<Carbide layer 2a>
The carbide layer 2a is a layer in which carbon is permeated and diffused from the surface of the steel material to precipitate metal carbides in the steel material. More specifically, the carbide layer 2a is derived from a peak derived from α-Fe by measurement by a tilt angle incident method using an X-ray diffraction analyzer and a metal carbide such as M6C type carbide, M23C6 type carbide, and M7C3 type carbide. It is a layer where a peak can be obtained. The amount of metal carbide on the surface of the steel material can be evaluated by looking at the ratio between the peak intensity derived from α-Fe and the peak intensity derived from metal carbides such as M6C type carbides, M23C6 type carbides, and M7C3 type carbides. can. The peak intensity in the present specification is calculated based on the analysis result performed under the conditions of the X-ray diffraction analysis described in the examples described later.

The maximum peak intensity of X-ray diffraction derived from α-Fe of a steel material in the present specification is the intensity of the maximum peak appearing in the vicinity of 2θ = 44.6 ° (for example, between 44.4 ° and 44.8 °). be. The maximum peak intensity of X-ray diffraction derived from metal carbides of steel materials in the present specification is the maximum peak appearing near 2θ = 42.5 (for example, between 42.3 ° and 42.7 °) for M6C type carbides. It is the intensity of the maximum peak appearing in the vicinity of 2θ = 44 ° for M23C6 type carbide and M7C3 type carbide. In the X-ray diffraction pattern, X-ray diffraction peaks appearing near 2θ = 42.5 ° and 2θ = 44 ° (for example, 43.8 ° to 44 °) as peaks of X-ray diffraction derived from metal carbides of steel materials. When both X-ray diffraction peaks appearing near (between 2 °) appear together, the peak intensity with the stronger peak intensity is taken as the maximum peak intensity of X-ray diffraction derived from metal carbide. Further, the measurement of the peak intensity in the present specification is performed by fitting a curve representing the intensity distribution obtained by the X-ray diffractometer and using the curve after the fitting. For example, the maximum peak intensity of the X-ray diffraction derived from α-Fe means the intensity of the maximum peak appearing in the vicinity of 2θ = 44.6 ° of the intensity curve after fitting.

The steel grade is high-speed tool steel (high-speed steel) such as SKH51, so-called cold tool steel such as SKD11 and DC53 trade name manufactured by Daido Special Steel Co., Ltd., or cold die steel (cold die steel). In the case of), it _{is presumed that Fe 6} C, W ₆ C, Cr ₆ C, V ₆ C and the like are deposited as M6C type carbides.

Here, the ratio of the maximum peak intensity [carbide intensity] of X-ray diffraction derived from the metal carbide of the steel material obtained by the tilt angle incident method to the maximum peak intensity [Fe intensity] of the X-ray diffraction derived from α-Fe. Is defined as the peak intensity ratio [carbide intensity / Fe intensity]. The carbide layer 2a is a layer having a peak intensity ratio of 0.5 to 4.0. When the peak intensity ratio is less than 0.5, the amount of metal carbides deposited in the steel material 2 is small, and the effect of improving the adhesion between the steel material 2 and the metal carbide film 3 cannot be obtained. Further, when the peak strength ratio exceeds 4.0, a large amount of cementite is deposited in the steel material 2, the steel material becomes brittle, and the effect of improving the adhesion cannot be obtained.

When the metal carbide film 3 described later is formed on the carbide layer 2a having a peak intensity ratio of 0.5 to 4.0, the adhesion between the steel material 2 and the metal carbide film 3 in the Rockwell indentation test is improved. The reason why the adhesion is improved is not clear, but it is considered that the adhesion is improved by improving the chemical compatibility between the steel material 2 and the metal carbide film 3 and eliminating the inconsistency of the lattice. When the metal carbide film 3 is, for example, a silica carbide vanadium film, the peak intensity ratio is preferably 0.6 or more, and more preferably 0.7 or more. Further, when the metal carbide film 3 is, for example, a silica carbide vanadium film, the peak intensity ratio is preferably 2.0 or less, more preferably 1.0 or less.

<Metal carbide film>
The metal carbide film 3 formed on the steel material 2 is a film containing one or more metals and carbon selected from the group consisting of V, Ti, Al, Cr, Nb and Si. For example, the metal carbide film 3 includes VC (vanadium carbide), TiC (titanium carbide), AlC (aluminum carbide), CrC (chromium carbide), NbC (niobium carbide), SiC (silicon carbide), VCS (vanadium carbide). , TiSiC (Titanium Carbide) and other metal carbides are contained in the whole or part of the film. When the metal carbide film covering member 1 is applied to a press forming mold or various tools (cutting tool, gear cutting tool, forging tool, etc.), the metal carbide film 3 is VC (vanadium carbide) or VCSC (silica). It is preferably a vanadium-based film such as vanadium carbide). The vanadium-based film can be used for high-speed tool steel such as SKH51, cold tool steel such as SKD11 and DC53, or steel for cold dies, which are generally used as materials to be molded in press-formed products and steel materials for various tools. On the other hand, it is a film with excellent lubricity and can effectively suppress damage due to contact friction with the mating material.

The metal carbide film 3 preferably has a total of 90 at% or more of the element concentration of one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si and the carbon element concentration. It is more preferably 93 at% or more, and further preferably 95 at% or more. Further, the metal carbide film 3 may contain a non-metal element of 10 at% or less, excluding the carbon element. Examples of non-metal elements include fluorine, argon, chlorine and hydrogen contained in the raw material gas supplied in the process of forming the metal carbide film 3, and oxygen and nitrogen contained in the residual gas in the chamber of the film forming apparatus. Can be mentioned. The non-metal element contained in the metal carbide film 3 is preferably 7 at% or less. More preferably, it is 5 at% or less. The metal element concentration and the carbon element concentration in the metal carbide film 3 can be measured by composition analysis by EPMA.

When the metal carbide film 3 is a silica carbide vanadium film, it is preferable that the vanadium element concentration is 8 to 30 at%, the silicon element concentration is 8 to 30 at%, and the carbon element concentration is 40 to 80 at%. When the vanadium element concentration is 8 to 30 at%, the effect of improving the lubricity derived from vanadium is likely to be obtained, and the coefficient of friction between the silica carbide vanadium film and other members is likely to be low. When the silicon element concentration is 8 to 30 at%, amorphous silicon carbide (SiC) is likely to be formed in the silica carbide vanadium carbide film, and an oxide film is formed on the film surface when the silica carbide vanadium carbide film slides with other members. Therefore, the friction coefficient between the silica carbide vanadium film and other members tends to be low. When the carbon element concentration is 40 to 80 at%, amorphous silicon carbide (SiC) or amorphous carbon is likely to be formed in the silica carbide vanadium carbide film, and the coefficient of friction between the silica carbide vanadium film and other members is likely to be low. The vanadium element concentration is more preferably 9 at% or more. Further, the vanadium element concentration is more preferably 25 at% or less. The silicon element concentration is more preferably 9 at% or more. Further, the silicon element concentration is more preferably 25 at% or less. The carbon element concentration is more preferably 50 at% or more. Further, the carbon element concentration is more preferably 80 at% or less.

The film thickness of the metal carbide film 3 is appropriately changed according to the characteristics required for the metal carbide film covering member 1, but is preferably 0.5 to 4 μm, for example.

When the metal carbide film 3 is used as a hard film for automobile parts such as molds, tools, and gears, the hardness of the metal carbide film 3 is preferably 2000 HV or more, and preferably 4000 HV or less. preferable.

Next, a method for manufacturing the metal carbide film covering member 1 will be described. The manufacturing method described below comprises a plasma carbonization treatment step of forming a carbide layer 2a on the surface of the steel material and a metal carbide film forming step of coating the metal carbide film 3 on the steel material 2 subjected to the plasma carbonization treatment step. ..

<Plasma carbonization process>
In the plasma carbonization treatment step of the steel material, carbon is permeated and diffused from the surface of the steel material before the metal carbide film 3 is formed on the steel material 2, and the metal carbide is precipitated in the steel material, and the peak intensity ratio is 0.5 to 4 This is a step of forming the carbide layer 2a to be 0.0. Even if the steel material has a low peak intensity ratio, the peak intensity ratio can be increased by performing this step. In the case of SKH51, which is a kind of high-speed tool steel, it is possible to increase the peak strength ratio by 3 times or more by performing this step.

In the plasma carbonization treatment step, a method for forming the carbide layer 2a of the steel material 2 includes plasma carbonization treatment. The plasma carbonization treatment is a treatment in which hydrogen gas and carbon source gas supplied as a treatment gas are turned into plasma, and the steel material is placed in a plasma-like atmosphere to deposit metal carbides on the surface of the steel material. According to the plasma carbonization treatment, the atmospheric temperature during the plasma carbonization treatment step can be set to 350 to 650 ° C., so that the strain due to heat of the steel material 2 can be suppressed. Further, the plasma carbonization treatment can suppress the generation of soot, which simplifies the maintenance work.

In the plasma carbonization treatment step, for example, the film forming apparatus 10 as shown in FIG. 2 can be used. The film forming apparatus 10 includes a chamber 11 into which the steel material 2 is carried, an electrode member 12 on the anode side, an electrode member 13 on the cathode side, and a pulse power supply 14. A gas supply pipe 15 to which a processing gas or a raw material gas is supplied is connected to the upper part of the chamber 11, and a gas exhaust pipe 16 for exhausting the gas in the chamber 11 is connected to the lower part of the chamber 11. The gas exhaust pipe 16 is provided with a vacuum pump (not shown). The electrode member 13 on the cathode side also serves as a support base for supporting the steel material 2, and the steel material 2 carried into the chamber 11 is placed on the cathode. Further, a heater (not shown) is provided inside the chamber 11, and the temperature of the steel material is adjusted by adjusting the atmospheric temperature in the chamber 11 with the heater. When the metal carbide film 3 is formed by the plasma CVD method as described later, if the film forming apparatus 10 as shown in FIG. 2 is used, the plasma carbide treatment step of the steel material 2 and the metal carbide film forming step are performed by the same apparatus. This makes it possible to efficiently manufacture the metal carbide film covering member 1 as compared with the case where separate devices are used. Further, by performing the plasma carbide treatment step of the steel material 2 and the metal carbide film forming step in the same apparatus, it is possible to suppress the formation of an oxide layer at the interface between the carbide layer 2a and the metal carbide film 3.

In the plasma carbonization treatment step, as the carbon source gas as the treatment gas, for example, a hydrocarbon gas such as methane gas, ethane gas, ethylene gas, and acetylene gas is used. The gas exemplified here may be supplied alone or may be supplied as a mixture of two or more kinds of gases. It is preferable to use the same gas as the carbon source gas used in the step of forming the metal carbide film 3 described later. From the viewpoint of obtaining the metal carbide film covering member 1 having better adhesion, it is preferable to use methane gas as the carbon source gas. Further, as the processing gas, argon gas may be supplied in addition to hydrogen gas and carbon source gas. Argon gas is preferably supplied as needed because it contributes to the stabilization of plasma and the improvement of ion density by ionizing other molecules by argon ions. The flow rate of each gas is a "volume flow rate" and is controlled by the mass flow controller. The "volumetric flow rate" in the present specification is a "flow rate converted to a standard state" that does not depend on the actual operating temperature and pressure of the gas, and the "standard state" is 101.3 kPa (1 atm), 0 ° C.

In the plasma carbonization treatment, the flow ratio [carbon source gas flow rate / hydrogen gas flow rate] between the carbon source gas supplied as the treatment gas and the hydrogen gas is preferably 0.01 to 0.40. When the carbon source gas flow rate / hydrogen gas flow rate is 0.01 or more, it becomes easier to form the carbide layer 2a in the steel material 2, and the adhesion between the steel material 2 and the metal carbide film 3 in the metal carbide film covering member 1 is further improved. Can be improved. When the carbon source gas flow rate / hydrogen gas flow rate is 0.40 or less, the formation of amorphous carbon that reduces the adhesion is suppressed, and the adhesion between the steel material 2 and the metal carbide film 3 in the metal carbide film covering member 1 is further improved. Can be improved. The carbon source gas flow rate / hydrogen gas flow rate may be varied during the plasma carbonization treatment step as long as it is in the range of 0.01 to 0.40, but it is preferably constant. The carbon source gas flow rate / hydrogen gas flow rate is preferably 0.02 or more. Further, the carbon source gas flow rate / hydrogen gas flow rate is preferably 0.20 or less.

In plasma carbonization treatment using hydrogen gas, carbon source gas and argon gas as the treatment gas, the ratio of hydrogen gas: carbon source gas: argon gas volume flow rate is 1: when the volume flow rate of hydrogen gas is 1. 0.01 to 0.40: Preferably 0.01 to 0.10. More preferably, the ratio of the volumetric flow rate of hydrogen gas: carbon source gas: argon gas is 1: 0.02 to 0.20: 0.01 to 0.10.

When the plasma carbonization treatment is performed by the film forming apparatus 10 of FIG. 2, a pulse is formed between the electrode member 12 on the anode side and the electrode member 13 on the cathode side while hydrogen gas and carbon source gas are supplied into the chamber 11. Apply voltage. Here, by adjusting the ambient temperature, duty ratio, voltage, and pressure inside the chamber 11, hydrogen gas and carbon source gas can be turned into plasma.

In order to suppress the softening of the steel material 2 due to heat during the carbonization treatment, the atmospheric temperature in the chamber 11 is preferably 350 to 650 ° C. The atmospheric temperature in the chamber 11 is preferably 400 ° C. or higher, preferably 550 ° C. or lower. The atmospheric temperature in the chamber 11 can be adjusted by changing the heater set temperature according to the plasma conditions.

The duty ratio is defined by the voltage application time per pulse cycle, and the duty ratio (%) = 100 × voltage application time (ON time) / {voltage application time (ON time) + voltage application stop time (OFF time)} It is calculated by. When the DC pulse power supply 14 is used, the duty ratio in the plasma carbonization treatment is preferably 5% to 90%. The duty ratio is preferably 15% or more, and preferably 60% or less. The voltage of the pulse power supply 14 in the plasma carbonization treatment is preferably 1000 to 2000 V. The voltage of the pulse power supply 14 is preferably 1100 V or more, and preferably 1800 V or less.

In the plasma carbonization treatment, the power density when a pulse voltage is applied between the electrode member 12 on the anode side and the electrode member 13 on the cathode side is preferably ^{1200 to 2000 W / m 2, for example.} The power density is preferably 1400 W / m ² or more. The power density is preferably 1800 W / m ² or less. The power density [W / m ² ] is a value calculated by power [W] / cathode surface area [m ^2]. “Cathode surface area [m ² ]” is the total value of the surface area of the steel material 2 and the surface area of the electrode member 13 on the cathode side. For example, in the film forming apparatus 10 of FIG. 2, since the steel material is placed on the electrode member 13 on the cathode side, a voltage is also applied to the steel material via the electrode member 13 on the cathode side when energized. That is, the steel material 2 becomes a cathode by being electrically connected to the electrode member 13 on the cathode side. Therefore, the surface area of the cathode in the film forming apparatus 10 is the total value of the surface area of the electrode member 13 on the cathode side and the surface area of the steel material. The area of the contact surface between the electrically connected members is not included in the surface area of the cathode. Further, when the steel material is set on a jig (not shown) and the jig is placed on the electrode member 13 on the cathode side to perform plasma carbonization treatment, the electrode member 13 on the cathode side, the jig, and the jig are used. It is electrically connected to the steel material. In this case, the total surface area of the electrode member 13 on the cathode side, the surface area of the jig, and the surface area of the steel material excluding the area of the contact surface between the electrode member 13 on the cathode side and the jig and the area of the contact surface between the jig and the steel material. The value is the surface area of the cathode. "Power [W]" is a value calculated by voltage [V] x current [A]. "Voltage" is the set voltage of the pulse power supply 14, and "current" is a value calculated by (maximum current + minimum current) / 2 in the plasma carbonization processing process using the current value displayed on the pulse power supply 14. Is.

The pressure in the chamber 11 is preferably set to 30 to 200 Pa. In order to make the plasma more stable and facilitate the carbonization treatment, the pressure in the chamber 11 is preferably 40 Pa or more, preferably 100 Pa or less. The processing time of the plasma carbonization treatment process differs depending on the type and shape of the steel material. Therefore, the carbonization treatment time is appropriately changed, but is preferably 60 to 360 minutes, for example. The carbonization treatment time is preferably 120 minutes or more, and preferably 300 minutes or less.

In the plasma carbonization treatment step, as long as hydrogen gas and carbon source gas, which are treatment gases, can be converted into plasma, the means for converting the treatment gas into plasma is not particularly limited.

By the plasma carbonization treatment step as described above, a steel material 2 having a carbide layer 2a having a peak intensity ratio [carbide strength / Fe strength] of 0.5 to 4.0 can be obtained.

The peak strength ratio of the steel material 2 after the plasma carbonization treatment step / the peak strength ratio of the steel material before the plasma carbonization treatment step is preferably 2.4 to 19. By performing the plasma carbonization treatment step so that the peak intensity ratio of the steel material 2 after the plasma carbonization treatment step and the peak intensity ratio of the steel material before the plasma carbonization treatment step satisfy the above relationship, the steel material 2 and the metal carbide film 3 adhere to each other. It becomes easier to improve the sex.

<Metal carbide film forming process>
Next, a metal for coating the surface of the steel material after the plasma carbide treatment step with a metal carbide film 3 containing one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si and carbon. Carbide film forming step is performed.

In the metal carbide film forming step, the metal carbide film 3 may be formed by any method as long as the metal carbide film 3 can be formed. Examples of the method for forming the metal carbide film 3 include a plasma CVD method, an arc ion plating method, a sputtering method, and an unbalanced magnetron sputtering method. The plasma CVD method is preferable. When the metal carbide film 3 is formed by the plasma CVD method, the plasma carbide treatment of the steel material 2 and the film formation of the metal carbide film 3 can be performed by the same plasma processing device, as compared with the case where different devices are used. Therefore, the metal carbide film covering member 1 can be efficiently manufactured. Further, by performing the plasma carbide treatment of the steel material 2 and the film formation of the metal carbide film 3 with the same apparatus, it is possible to suppress the formation of an oxide layer at the interface between the carbide layer 2a and the metal carbide film 3.

When the metal carbide film 3 is formed by the plasma CVD method, the raw material gas includes a gas containing one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si, a carbon source gas, and the like. Hydrogen gas is supplied into the chamber 11, and a pulse voltage is applied between the electrode member 12 on the anode side and the electrode member 13 on the cathode side using the pulse power supply 14. As a result, the raw material gas is turned into plasma between the electrode member 12 on the anode side and the electrode member 13 on the cathode side, and the metal carbide film 3 is formed on the surface of the steel material 2. As a gas containing one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si, as an example of V, vanadium chloride gas, as an example of Ti, titanium chloride gas, as an example of Al. Is an aluminum chloride gas, an example of Cr is chromium chloride gas, an example of Nb is niobium chloride gas, and an example of Si is silicon chloride gas.

When the silica carbide vanadium film is formed as the metal carbide film 3, for example, vanadium tetrachloride (VCl ₄ ) gas and vanadium trichloride (VOCl ₃ ) gas are used as the vanadium chloride gas. It is preferable to use vanadium tetrachloride gas as the vanadium chloride gas from the viewpoint that the number of elements constituting the gas is small and impurities in the silica carbide vanadium film can be easily removed. Further, vanadium tetrachloride gas is preferable because it is easily available, is a liquid at room temperature, and is easily supplied as a gas.

As the silicon source gas, for example, a silane gas such as monosilane gas, disilane gas, dichlorosilane gas, trichlorosilane gas, silicon tetrachloride gas, or silicon tetrachloride gas is used. The gas exemplified here may be supplied alone or may be supplied as a mixture of two or more kinds of gases. Further, among these gases, it is preferable to use _{silicon tetrachloride (SiCl 4} ) gas, which can easily remove chlorine atoms by hydrogen plasma, is thermally stable, and decomposes only in plasma.

As the carbon source gas, for example, a hydrocarbon gas such as methane gas, ethane gas, ethylene gas, and acetylene gas is used. The gas exemplified here may be supplied alone or may be supplied as a mixture of two or more kinds of gases. It is preferable to use methane gas. By using methane gas, it becomes easy to control the amount of carbon, and by containing a large amount of hydrogen in the membrane, the amount of chlorine in the membrane can be reduced.

Further, when the silica carbide vanadium film is formed as the metal carbide film 3, an organic silane gas having a molecular structure in which a hydrocarbon functional group is bonded to silicon may be used as a gas that serves as both a silicon source gas and a carbon source gas. The organic silane gas is not particularly limited as long as it has a molecular structure in which a hydrocarbon functional group is bonded to silicon, and for example, monomethylsilane gas, dimethylsilane gas, trimethylsilane gas, tetramethylsilane gas and the like may be used. When forming a silica carbide vanadium film as the metal carbide film 3, a mixed gas of an organic silane gas and a carbon source gas may be used.

When the silica carbide vanadium film is formed as the metal carbide film 3, if the raw material gas contains vanadium chloride gas, the silica carbide vanadium film inevitably contains the residue excluding vanadium, silicon and carbon as impurities. Contains chlorine. Since hydrogen gas is easily combined with chlorine, when the raw material gas contains hydrogen gas, chlorine generated from vanadium chloride gas is easily combined with hydrogen and discharged to the outside of the system. As a result, it is possible to suppress the mixing of chlorine into the silica carbide vanadium carbide film. The rest of the silica carbide vanadium film may contain unavoidable impurities other than chlorine.

When vanadium chloride gas and silicon tetrachloride gas are supplied as raw material gas in the metal carbide film forming step, the volumetric flow rate of the hydrogen gas supplied into the chamber 11 is the volumetric flow rate of vanadium chloride gas and the volume of silicon tetrachloride gas. It is preferably 5 to 25 times the total flow rate.

When vanadium chloride gas, silicon source gas, carbon source gas, hydrogen gas, and argon gas are supplied as raw material gas in the metal carbide film forming step, when the volumetric flow rate of vanadium chloride gas is 1, vanadium chloride gas and The ratio of the volumetric flow rates of the silicon source gas, the carbon source gas, the hydrogen gas, and the argon gas is preferably 1: 0.25 to 2: 3 to 20:20 to 35: 0.5 to 2. This makes it easy to obtain a silica carbide vanadium film having a total of 90 at% or more of the vanadium element concentration, the silicon element concentration, and the carbon element concentration in the film.

Since the argon gas contributes to the stabilization of the plasma and the improvement of the ion density by ionizing other molecules by the argon ion, it is supplied into the chamber 11 as needed in the metal carbide film forming step.

The pressure in the chamber 11 in the metal carbide film forming step is preferably set to, for example, 30 to 200 Pa. The pressure in the chamber 11 is more preferably 50 to 150 Pa. Further, the electric power supplied in the metal carbide film forming step is preferably 200 to 2500 W. "Power [W]" is a value calculated by voltage [V] x current [A]. The “voltage” is the set voltage of the pulse power supply 14. The "current" is a value calculated by (maximum current + minimum current) / 2 in the metal carbide film forming step using the current value displayed on the pulse power supply 14. The electric power can be adjusted by changing the setting value of the duty ratio. When the DC pulse power supply 14 is used, the voltage in the metal carbide film forming step is preferably 1000 to 2000 V. When the DC pulse power supply 14 is used, the duty ratio in the metal carbide film forming step is preferably 5% to 60%.

By the metal carbide film forming step as described above, a metal carbide film containing one or more metals and carbon selected from the group consisting of V, Ti, Al, Cr, Nb and Si on the carbide layer 2a of the steel material 2. 3 is formed. This makes it possible to manufacture the metal carbide film covering member 1 having excellent adhesion in the Rockwell indentation test.

Although an example of the embodiment of the present invention has been described above, the present invention is not limited to such an example. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs to.

A test piece of a metal carbide coating member having a silica carbide vanadium film formed as a metal carbide film on a steel material having a carbide layer formed on the surface of the steel material was prepared by plasma carbonization treatment, and the following measurements were performed.

<X-ray diffraction analysis>
In the X-ray diffraction analysis, an X-ray diffraction analyzer (SmartLab manufactured by Rigaku Co., Ltd.) was used, and in order to obtain only information near the surface of the test piece, the analysis was carried out under the following conditions by the tilt angle incident method.
-------------------------------------------------- -------------------------------------------------- -------------------
Incident angle: 1.0 °
X-ray source: CuKα ray
X-ray output: 40kV, 20mA
Scan axis: 2θ / θ
Goniometer: RINT2000 Wide-angle goniometer Scan range: 20 ° -80 °
Detector: Scintillation counter Incident slit: 1 °
Scan mode: STEP
Longitudinal limiting slit: 10 mm
Scan speed: 1.0sec
Light receiving slit 1: 1.25 mm
Step width: 0.05 °
Light receiving slit 2: 0.3 mm
-------------------------------------------------- -------------------------------------------------- -------------------
Then, from the X-ray diffraction pattern obtained by the X-ray diffraction analysis under the above conditions, the maximum peak intensity [carbide intensity] of the X-ray diffraction derived from the metal carbide and the maximum peak intensity of the X-ray diffraction derived from α-Fe are obtained. [Fe strength] was specified. The maximum peak intensity is specified as follows using the solver function of Excel (registered trademark) 2010. First, from the X-ray diffraction pattern obtained by X-ray diffraction analysis, the peaks having peak tops at the diffraction angles around 2θ = 42.5 ° and 2θ = 44.6 ° are the Gaussian basic waveform and the linear background. Approximate by superimposing. Next, peak separation is performed by optimizing the peak intensity, full width at half maximum and peak position, and curve-fitting each of the two overlapping peaks included in the peak. Then, the maximum value of the Gaussian function at this time obtained by the fitting was taken as the maximum peak intensity. Curve fitting is performed by the least squares method.

<Membrane hardness measurement>
It is carried out by the nanoindentation method using FISCHER SCOPE® H100C manufactured by Fischer Instruments. Specifically, a Berkovich-type diamond indenter is pushed into the test piece with a maximum pushing load of 3 mN, and the pushing depth is continuously measured. Vickers hardness converted from Martens hardness and Martens hardness using "Product name: WIN-HCU (registered trademark)", which is software manufactured by Fisher Instruments, from the obtained measurement data of the indentation depth. Calculate the hardness. The calculated Vickers hardness is displayed on the screen of the measuring device, and this value is treated as the hardness of the film at the measurement point. In this example, the Vickers hardness of any 20 points on the outermost surface of each test piece was obtained, and the average value of the obtained hardness was taken as the Vickers hardness of the silica carbide vanadium film.

<Film thickness measurement>
The thickness of the silica carbide vanadium film is calculated by cutting the test piece vertically, polishing the cut surface with a mirror surface, observing the cut surface at a magnification of 1000 times with a metallurgical microscope, and calculating based on the observed image information. It was measured.

<Composition analysis of silica carbide vanadium carbide>
The composition of the silica carbide vanadium carbide film formed on the test piece was analyzed. The analysis conditions are as follows.
EPMA: JXA-8530F manufactured by JEOL Ltd.
Measurement mode: Semi-quantitative analysis Acceleration voltage: 15kV
Irradiation current: 1.0 × 10 ^-7 A
Beam shape: Spot Beam diameter set value: 0
Spectral crystals: LDE6H, TAP, LDE5H, PETH, LIFH, LDE1H

<Rockwell indentation test>
The Rockwell hardness tester is set on the C scale to give indentations to the surface of the silica carbide vanadium film of the test piece. Then, the circumference of the indentation was observed using a metallurgical microscope. Then, the degree of film peeling of the test piece was determined based on the well-known indentation peeling criteria in the Rockwell indentation test, and the adhesion of the silica carbide vanadium film coating member was evaluated.

The test piece is prepared by the following procedure. First, a φ22 round bar made of SKH51, which is a kind of high-speed tool steel, is cut at intervals of 6 to 7 mm, and a mirror-polished surface of the cut round bar as shown in FIG. 3 is tested. Used as a steel material for one piece. As the film forming apparatus, an apparatus having a structure as shown in FIG. 2 was used, and a pulse power source was used as a power source.

<Confirmation of oxide layer formation>
10 ml of Schumer plating solution (Blue Schumer 2L) manufactured by Japan Kanigen Co., Ltd. was prepared, and 40 ml of purified water was added to adjust the total to 50 ml to prepare a plating solution. The above-mentioned test piece for microstructure photograph measurement was put in this plating solution and kept at 120 ° C. for 2 hours. After holding for 2 hours, the test piece was taken out from the plating solution, and the test piece was cut in the direction perpendicular to the film forming surface using a cutting machine. This cut test piece was embedded in a resin to prepare a sample. Then, the cross section of the sample was polished with emery paper, and the polished surface was mirror-finished with a buff. Then, based on the nitric acid alcohol method (Nital method) specified in JIS G 0553, nitric acid (JIS K)
Ethanol was mixed with (equivalent to 62% of 1308) and the sample was immersed in the resulting 3% nitric acid corrosive solution for 5 minutes. Then, the cross section of the sample was observed at a magnification of 10000 times using a field emission scanning electron microscope (JSM-7001F manufactured by JEOL Ltd.), and a cross section image was obtained. Then, from the obtained cross-sectional image, it was observed whether an oxide layer was formed at the interface between the carbide layer and the metal carbide film. Since the grain boundaries of the oxide layer are usually preferentially oxidized and observed in a darker color than the normal structure when observed with an electron microscope, it is possible to determine the presence or absence of the oxide layer based on its color and shape. be.

<< Example 1 >>
First, a steel material for a test piece is set in the chamber of the film forming apparatus, and the inside of the chamber is evacuated for 30 minutes to reduce the pressure in the chamber to 10 Pa or less. At this time, the heater is not operated. The heater is provided inside the chamber, and the atmospheric temperature inside the chamber is measured by a sheath thermocouple. Subsequently, the set temperature of the heater is set to 200 ° C., and the baking process of the steel material is performed for 10 minutes. After that, the power of the heater is turned off, and the film forming apparatus is left for 30 minutes to cool the inside of the chamber.

Next, hydrogen gas is supplied into the chamber at a flow rate of 100 ml / min, and the displacement is adjusted so that the pressure in the chamber is 100 Pa. Then, the atmosphere in the chamber is heated for 30 minutes so that the temperature of the atmosphere in the chamber becomes 525 ° C.

Next, set the voltage to 800V and the duty ratio to 40%, and operate the DC pulse power supply in the unipolar output format. As a result, hydrogen gas is turned into plasma between the electrodes in the chamber. After that, the flow rate of hydrogen gas is set to 98 ml / min, and argon gas having a flow rate of 3 ml / min is supplied into the chamber. Further, the displacement is adjusted so that the total pressure in the chamber becomes 58 Pa. Then, the voltage of the pulse power supply is set to 1400 V, the duty ratio is set to 40%, and the atmospheric temperature in the chamber is set to 525 ° C. As a result, hydrogen gas and argon gas are turned into plasma between the electrodes.

<Plasma carbonization process>
Next, the flow rate of hydrogen gas as the processing gas is set to 98 ml / min, the flow rate of methane gas as the carbon source gas is set to 5 ml / min, and the flow rate of argon gas is set to 3 ml / min, and the gas is supplied into the chamber. The total pressure in the chamber is maintained at 58 Pa, the atmosphere temperature in the chamber is set to 525 ° C, the voltage of the pulse power supply is set to 1400 V, the Duty ratio is set to 40%, and the atmosphere is plasmated with hydrogen gas, methane gas and argon gas. , The steel material is subjected to plasma carbonization treatment for 120 minutes. The flow rate ratio [carbon source gas flow rate / hydrogen gas flow rate] between methane gas, which is a carbon source gas supplied as a treatment gas, and hydrogen gas is 0.05.

FIG. 4 shows the results of X-ray diffraction analysis of the test piece subjected to the carbonization treatment under the above conditions. As shown in FIG. 4, both the test piece before the plasma carbonization treatment step and the test piece after the plasma carbonization treatment step have a diffraction peak derived from α-Fe near 2θ = 44.6 °, and 2θ = 42. A diffraction peak derived from M6C type carbide was present near 5 °. The test piece after the plasma carbonization treatment step has a weaker diffraction peak intensity derived from α-Fe and a stronger diffraction peak intensity derived from the metal carbide which is an M6C type carbide than the test piece before the plasma carbonization treatment step. There is. From the results shown in FIG. 4, it was confirmed that carbon permeated and diffused from the surface of the steel material, metal carbides were deposited in the steel material, and a carbide layer was formed in the steel material.

The conditions of the plasma carbonization treatment step of Example 1 above are shown in Table 1 below. In addition, Table 1 also shows the carbonization conditions of Examples 2 to 3 and Comparative Example 1 described later.

<Vanadium carbide film forming process>
After the plasma carbonization treatment step, the flow rate of vanadium tetrachloride gas as vanadium chloride gas is 3 ml / min, the flow rate of silicon tetrachloride gas as an example of silicon source gas is 4.5 ml / min, as an example of carbon source gas. The flow rate of methane gas is set to 15 ml / min, the flow rate of hydrogen gas is set to 98 ml / min, and the flow rate of argon gas is set to 3 ml / min, and each gas is supplied into the chamber. In other words, the flow rate ratio of vanadium tetrachloride gas, silicon tetrachloride gas, carbon source gas, hydrogen gas and argon gas is 1: 1.5: 5: 33: 1 when the flow rate of vanadium tetrachloride gas is 1. Each gas is supplied so as to be. At this time, the displacement is adjusted so that the pressure in the chamber is 58 Pa. Then, the voltage of the pulse power supply is set to 1400 V, and the duty ratio is set to 40%. The power of the pulse power supply at this time is 420 W. As a result, each gas is turned into plasma, vanadium, silicon, and carbon are adsorbed on the steel material, and a silica carbide vanadium film containing vanadium, silicon, and carbon is formed on the steel material having a carbide layer on the surface. The silica carbide vanadium film forming treatment under the above conditions was carried out for 4 hours, and the silica carbide vanadium film having a film thickness of 1.2 μm was coated on the steel material to obtain the test piece of Example 1.

The Rockwell indentation test was performed on the test piece of Example 1 by the above-mentioned method. As the test result, an image of the indented portion of the test piece of Example 1 after the Rockwell indentation test is shown in FIG. The Rockwell indentation test result was determined to be HF1 based on the indentation peeling criterion.

<< Example 2 >>
In the plasma carbonization treatment step, a test piece was prepared under the same conditions as in Example 1 except that the plasma carbonization treatment step was performed for 4 hours. An image of the indented portion of the test piece of Example 2 after the Rockwell indentation test is shown in FIG. The Rockwell indentation test result was determined to be HF1 based on the indentation peeling criterion.

<< Example 3 >>
In the plasma carbonization treatment step, the flow rate of methane gas supplied as the treatment gas is set to 3 ml / min, and the flow rate ratio of the carbon source gas methane gas to hydrogen gas [carbon source gas flow rate / hydrogen gas flow rate] is set to 0.03. , A test piece was prepared under the same conditions as in Example 1 except that the plasma carbonization treatment step was carried out for 4 hours. An image of the indentation portion of the test piece of Example 3 after the Rockwell indentation test is shown in FIG. The Rockwell indentation test result was determined to be HF1 based on the indentation peeling criterion.

<< Comparative Example 1 >>
A test piece was prepared under the same conditions as in Example 1 except that the plasma carbonization treatment step was not carried out. An image of the indentation portion of the test piece of Comparative Example 1 after the Rockwell indentation test is shown in FIG. The Rockwell indentation test result was determined to be HF4 based on the indentation peeling criterion.

From the results of the above Rockwell indentation test, in the test pieces of Examples 1 to 3 in which the silica carbide vanadium film was formed on the carbide layer of the steel material, the silica carbide vanadium film was directly formed on the steel material having no carbide layer. It can be seen that the member has better adhesion in the Rockwell indentation test than the test piece of Comparative Example 1.

Table 2 below shows the results of X-ray diffraction analysis performed on the test piece before the formation of the silica carbide vanadium film. Table 2 compares the peak intensity ratios of the test pieces before the formation of the vanadium carbide film. The peak intensity ratio of the test piece before the formation of the silica carbide vanadium film in Examples 1 and 3 is the peak intensity ratio of the carbide layer formed by the plasma carbonization treatment. On the other hand, since the plasma carbonization treatment is not performed in Comparative Example 1, the peak intensity ratio of the test piece before the formation of the silica carbide vanadium film is the peak intensity ratio of the steel material which has not been subjected to the plasma carbonization treatment. Table 2 also shows the ratio of the peak strength ratio of the steel material after the plasma carbonization treatment step of Example 1 to the peak strength ratio of the steel material before the plasma carbonization treatment step.

As shown in Table 2, the peak intensity ratio of the test piece of Example 1 in which the indentation peeling determination in the Rockwell indentation test is HF1 is 0.82, and the peak intensity ratio of the test piece of Example 3 is It is 0.63. On the other hand, the peak intensity ratio of the test piece of Comparative Example 1 in which the indentation peeling determination is HF4 is 0.16. That is, according to the results of this example, it can be seen that the adhesion between the steel material and the metal carbide film can be improved when the peak intensity ratio is within a specific range.

The ratio of the peak intensity ratio of the test piece of Example 1 to the peak intensity ratio of the test piece of Comparative Example 1, that is, the peak intensity ratio of the carbonized material layer after the plasma carbonization treatment / the peak of the steel material before the plasma carbonization treatment. The intensity ratio was 5.1. Further, in Example 3, the peak intensity ratio of the carbide layer after the plasma carbonization treatment / the peak intensity ratio of the steel material before the plasma carbonization treatment was 3.9.

Next, the film thickness of the test pieces of Examples 1 to 3 was measured and the composition of the silica carbide vanadium film was analyzed by the above-mentioned method. In addition, the film hardness of the test piece of Example 1 was also measured by the above-mentioned method. The results of the above film hardness measurement, film thickness measurement, and composition analysis of the silica carbide vanadium carbide film are shown in Table 3 below.

Next, an electron microscope image of a cross section of the sample prepared according to the above-mentioned procedure of <confirmation of oxide layer formation> was acquired. FIG. 9 is an electron microscope image showing a cross section of the sample of Example 1. In the sample of Example 1, it was confirmed that no oxide layer was formed at the interface between the carbide layer and the metal carbide film. In addition, electron microscope images were obtained in the same manner for the samples of Example 2 and Example 3, but no oxide layer was formed in any of the samples.

The present invention can be used for coating a hard film on a mold or a tool, for example, an automobile part such as a gear. That is, the metal carbide film covering member according to the present invention is used, for example, as a mold, a tool, or an automobile part.

1 Metal carbide film covering member 2 Steel material 2a Carbide layer 3 Metal carbide film 10 Formation device 11 Chamber 12 Electrode member on the anode side 13 Electrode member on the anode side 14 Pulse power supply 15 Gas supply pipe 16 Gas exhaust pipe

Claims

It is a metal carbide film covering member and
Steel materials with a carbide layer on the surface and
The carbide layer comprises one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si and a metal carbide film containing carbon.
The ratio of the maximum peak intensity [carbide strength] of X-ray diffraction derived from metal carbides of steel materials to the maximum peak intensity [Fe intensity] of X-ray diffraction derived from α-Fe is the peak intensity ratio [carbide strength / Fe strength]. ], The peak intensity ratio of the carbide layer is 0.5 to 4.0.
In the metal carbide film covering member according to claim 1,
The peak intensity ratio of the carbide layer is 2.0 or less.
In the metal carbide film covering member according to claim 1,
The peak intensity ratio of the carbide layer is 1.0 or less.
In the metal carbide film covering member according to claim 1,
The metal carbide film is a silica carbide vanadium film containing vanadium, silicon, and carbon.
In the silica carbide vanadium film, the total of the vanadium element concentration, the silicon element concentration, and the carbon element concentration in the film is 90 at% or more.
In the metal carbide film covering member according to claim 4,
The vanadium element concentration in the silica carbide vanadium film is 8 to 30 at%, the silicon element concentration is 8 to 30 at%, and the carbon element concentration is 40 to 80 at%.
A method for manufacturing a metal carbide film covering member.
A plasma carbide treatment process that forms a carbide layer on the surface of the steel material,
It has a metal carbide film forming step of forming a metal carbide film containing carbon and one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si on the carbide layer.
The ratio of the maximum peak intensity [carbide strength] of X-ray diffraction derived from metal carbides of steel materials to the maximum peak intensity [Fe intensity] of X-ray diffraction derived from α-Fe is the peak intensity ratio [carbide strength / Fe strength]. ], In the plasma carbide treatment step, the carbide layer is formed so that the peak intensity ratio of the carbide layer after the plasma carbide treatment step is 0.5 to 4.0.
In the method for manufacturing a metal carbide film covering member according to claim 6.
In the plasma carbonization treatment step, the carbide layer is provided so that [the peak intensity ratio of the steel material after the plasma carbonization treatment step / the peak intensity ratio of the steel material before the plasma carbonization treatment step] satisfies 2.4 to 19. Form.
A method for manufacturing a metal carbide film covering member.
A plasma carbide treatment process that forms a carbide layer on the surface of the steel material,
It has a metal carbide film forming step of forming a metal carbide film containing carbon and one or more metals selected from the group consisting of V, Ti, Al, Cr, Nb and Si on the carbide layer.
The plasma carbonization treatment step is performed in an atmosphere in which a carbon source gas supplied as a treatment gas and a hydrogen gas are converted into plasma.
In the method for manufacturing a metal carbide film covering member according to claim 8,
The carbon source gas flow rate / hydrogen gas flow rate, which is the flow rate ratio of the carbon source gas to the hydrogen gas, is 0.01 to 0.40.
In the method for manufacturing a metal carbide film covering member according to claim 9.
When hydrogen gas, carbon source gas and argon gas are supplied as the processing gas in the plasma carbonization treatment step and the volumetric flow rate of the hydrogen gas is 1, the ratio of the volumetric flow rate of hydrogen gas: carbon source gas: argon gas is It is 1: 0.01 to 0.40: 0.01 to 0.10.
In the method for manufacturing a metal carbide film covering member according to claim 8,
The carbon source gas is methane gas.
In the method for manufacturing a metal carbide film covering member according to claim 6.
The metal carbide film is a silica carbide vanadium film containing vanadium, silicon, and carbon.
In the silica carbide vanadium film, the total of the vanadium element concentration, the silicon element concentration, and the carbon element concentration in the film is 90 at% or more.
In the method for manufacturing a metal carbide film covering member according to claim 12,
The vanadium element concentration in the silica carbide vanadium film is 8 to 30 at%, the silicon element concentration is 8 to 30 at%, and the carbon element concentration is 40 to 80 at%.