A stainless steel material and a method for manufacturing the same

Abstract

The present application provides a kind of stainless steel material and its preparation method, stainless steel material includes: carbon film layer and first stainless steel base material;Wherein, the surface of the first stainless steel base material includes carburizing layer;The carbon film layer is covered on the first stainless steel base material, and adjacent with the carburizing layer.The presence of carburizing layer of the stainless steel material of the present application not only can improve the hardness, wear resistance and fatigue resistance of stainless steel, but also can improve its corrosion resistance.In addition, the carbon content of carburizing layer changes from the saturation state of the surface of stainless steel base material to the different depth of underlying carburizing layer, and there is no obvious boundary between carburizing layer and stainless steel base material, and there is no peeling phenomenon of general coating when thermal expansion or mechanical deformation occurs.Meanwhile, the phenomenon that the coating is caused by the different thermal expansion coefficients between stainless steel and corrosion-resistant coating and the potential difference between them to accelerate corrosion can be eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of corrosion protection, in particular to a stainless steel material and a preparation method thereof. BACKGROUND

[0002] Stainless steel is a most common corrosion-resistant metal material, which has a very wide range of applications, covering all aspects of life. Although stainless steel has self-passivation ability, it will still produce, for example, pitting corrosion, crevice corrosion, stress corrosion, intergranular corrosion and other situations due to environmental conditions, causing significant safety hazards.

[0003] Researchers have used various types of modified coatings to strengthen the surface properties of stainless steel, thereby preparing stainless steel materials with high corrosion and wear resistance. The modified coatings used in the prior art include noble metals, metal oxides, carbides, nitrides, carbon-based, polymers, multi-element composite coatings, etc.

[0004] The modified coatings used in the prior art each have certain defects.

[0005] Although the metal oxide coating can improve the corrosion resistance of the bipolar plate and reduce the cost, it also has certain problems, such as the existence of micropores in the metal nitride coating, which will cause the passivation of the base material, and long-term service may cause the coating to fall off, performance degradation and other problems.

[0006] Noble metals can play a good role in corrosion protection and prolong the service life, but the disadvantages of noble metal coatings are also very obvious. For example, the film layer formed by the noble metal coating is relatively thin, and in harsh environments, it is extremely likely to leak out of the metal substrate, causing the film layer to fail. At the same time, the high price and low reserves of noble metal materials greatly limit their application occasions.

[0007] Polymer coatings can limit the invasion of corrosive ions, oxygen and water, and improve the corrosion resistance of the coating, but a large number of researchers suggest that the performance of such coatings after long-term service still needs to be considered.

[0008] The carbon-based coating mainly refers to an amorphous carbon (a-C) coating, including a graphite-like structure and a diamond-like structure. The graphite-like carbon coating has a large sp2 / sp3 ratio, sp3 carbon hybridization can effectively resist corrosion of corrosive ions, and sp2 carbon bonding is conducive to improving electrical conductivity, and the a-C coating exhibits excellent corrosion resistance and good electrical conductivity, and the use and development of the a-C coating are one of the current research focuses of stainless steel corrosion prevention. At present, carbon-based thin films are coated on stainless steel substrates by arc ion plating, thermal chemical vapor deposition (CVD) or plasma-assisted chemical vapor deposition to obtain a protective layer. The carbon layer obtained by the above method is only limited to the surface of the stainless steel, and the adhesion between the carbon layer and the steel is weak, and the carbon layer will fall off after long-term service. In addition, the carbon coating has a low hardness and poor wear resistance, which will limit its use range. SUMMARY

[0009] In view of the above problems, the purpose of the present application is to overcome the defects of the existing stainless steel material coating that is easy to fall off and has poor wear resistance, so as to provide a stainless steel material with wear resistance, corrosion resistance and a coating that is not easy to fall off.

[0010] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0011] A stainless steel material, comprising: a carbon film layer 101 and a first stainless steel substrate 103; wherein,

[0012] The surface of the first stainless steel substrate 103 comprises a carburized layer 102; the carbon film layer 101 is covered on the first stainless steel substrate 103 and adjacent to the carburized layer 102.

[0013] In the above technical solution, the carbon film layer 101 is a graphite-like structure, or a diamond-like structure, or both a graphite-like structure and a diamond-like structure.

[0014] In the above technical solution, the thickness of the carbon film layer 101 is greater than 0 microns and less than or equal to 50 microns.

[0015] In the above technical solution, the thickness of the carburized layer 102 is greater than 0 nanometers and less than or equal to 500 nanometers.

[0016] The present application also provides a preparation method of a stainless steel material, for preparing the stainless steel material, the method comprising:

[0017] Step 1), placing a second stainless steel substrate 205 to be treated in a high-temperature tube furnace 201, and connecting the second stainless steel substrate 205 to the negative electrode of an electrode 203; placing a metal plate 204 with catalytic activity in the high-temperature tube furnace 201, and connecting the metal plate 204 to the positive electrode of the electrode 203;

[0018] Step 2), a protective gas is introduced into the vacuumized high-temperature tube furnace 201 through a gas passage 202 connected with the high-temperature tube furnace 201, and the electrode 203 is turned on;

[0019] Step 3), after the temperature in the high-temperature tube furnace 201 reaches a first predetermined temperature value, a reducing gas and a gas flow with carbon source molecules are introduced through the gas passage 202, the carbon source molecules are catalytically cracked to obtain positively charged active carbon groups 206, and the active carbon groups 206 act on the second stainless steel substrate 205 under the action of an electric field;

[0020] Step 4), when the reaction time reaches a first termination condition, the introduction of the gas flow with carbon source molecules into the high-temperature tube furnace 201 is stopped, and the electrode 203 is turned off;

[0021] Step 5), the working process of the high-temperature tube furnace 201 is stopped, and after cooling, a first stainless steel substrate 103 including a carburized layer 102 and a carbon film layer 101 covering the surface of the first stainless steel substrate 103 are obtained.

[0022] In the above technical solution, between the step 4) and the step 5), the method further comprises:

[0023] The temperature in the high-temperature tube furnace 201 is reduced to a second predetermined temperature value, and the temperature in the furnace is maintained at the second predetermined temperature value until the second predetermined temperature value reaches a second termination condition; wherein the second predetermined temperature value is lower than the first predetermined temperature value.

[0024] In the above technical solution, the first predetermined temperature value is greater than or equal to 600 DEG C and less than or equal to 1000 DEG C.

[0025] In the above technical solution, the first termination condition is greater than or equal to 1 minute and less than or equal to 120 minutes.

[0026] In the above technical solution, the voltage value of the electric field is greater than or equal to 5V and less than or equal to 380V.

[0027] In the above technical solution, the second termination condition is greater than or equal to 10 minutes and less than or equal to 90 minutes.

[0028] The present application has the following advantages due to the above technical solutions:

[0029] The stainless steel material of the present application penetrates carbon element in the stainless steel base material, and forms a carburized layer on the surface of the stainless steel base material. The existence of the carburized layer can not only improve the hardness, wear resistance and fatigue resistance of the stainless steel, but also improve the corrosion resistance. In addition, the carbon content of the carburized layer changes in gradient from the saturation state on the surface of the stainless steel base material to different depths of the carburized layer below, and the carburized layer has no obvious boundary with the stainless steel base material, and will not fall off as the general coating does when thermal expansion or mechanical deformation occurs. At the same time, the phenomenon of coating falling off due to the difference in thermal expansion coefficient between the stainless steel and the corrosion-resistant coating can be eliminated, and the potential difference between them can accelerate the corrosion phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 is a structural schematic diagram of the stainless steel material provided by the present application;

[0032] Figure 2 is a schematic diagram of the preparation device of the stainless steel material of the present application;

[0033] Figure 3 is a flow chart of the preparation method of the stainless steel material of the present application;

[0034] Figure 4 is a scanning electron microscope image of the surface of the stainless steel material obtained in Example 1;

[0035] Figure 5 is a Raman spectrum diagram of the stainless steel material obtained in Example 1;

[0036] Figure 6 is a Raman spectrum diagram of the stainless steel material obtained in Example 2;

[0037] Figure 7 is a Raman spectrum diagram of the stainless steel material obtained in Example 3. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions in the present application will be described clearly and completely in the following combined with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] In view of the defects of the existing stainless steel surface coating materials, the present application provides a stainless steel material with better corrosion resistance.

[0040] Figure 1 A schematic diagram of the stainless steel material provided by the present application is shown in Figure 1 The stainless steel material of the present application comprises: a carbon film layer 101 and a first stainless steel substrate 103; wherein the surface of the first stainless steel substrate 103 comprises a carburized layer 102; the carbon film layer 101 is covered on the first stainless steel substrate 103 and adjacent to the carburized layer 102.

[0041] The carbon film layer 101 is of a graphite-like structure (sp2), or of a diamond-like structure (sp3), or both the graphite-like structure and the diamond-like structure exist. When both the graphite-like structure and the diamond-like structure exist in the carbon film layer 101, the ratio between them can be controlled by process conditions. In particular, when the carbon film layer 101 only has the graphite-like structure (sp2), the carbon film layer 101 is a graphene layer.

[0042] The thickness of the carbon film layer 101 can be determined according to actual needs, and the general thickness range is greater than 0 microns and less than or equal to 50 microns.

[0043] The thickness of the carburized layer 102 can be determined according to actual needs, and the general thickness range is greater than 0 nanometers and less than or equal to 500 nanometers. The carburized layer 102 has the highest carbon content near the surface of the carbon film layer 101, and the carbon content gradually decreases as the distance from the carbon film layer 101 gradually increases.

[0044] The stainless steel material of the present application penetrates carbon elements in the stainless steel substrate, and forms a carburized layer on the surface of the stainless steel substrate. The existence of the carburized layer not only improves the hardness, wear resistance and fatigue resistance of the stainless steel, but also improves its corrosion resistance. In addition, the carbon content of the carburized layer changes in a gradient from the saturation state on the surface of the stainless steel substrate to different depths of the carburized layer below, and the carburized layer and the stainless steel substrate have no obvious boundary, and the peeling phenomenon of general coatings does not occur when thermal expansion or mechanical deformation occurs. At the same time, the phenomenon of peeling of the stainless steel and the corrosion-resistant coating due to the difference in thermal expansion coefficient, the potential difference between them and the accelerated corrosion phenomenon can be eliminated.

[0045] The carbon film layer in the stainless steel material of the present application can be graphite-like structure (sp2), diamond-like structure (sp3), or both graphite-like structure and diamond-like structure. This makes the stainless steel material of the present application applicable in both conductive and non-conductive environments, with a very wide range of applications. When the carbon film layer is a graphene layer (i.e. the carbon film layer is entirely graphite-like structure), the stainless steel material can also be applied in the fields of bipolar plates, alkali-resistant, and strong acid and strong alkali metal.

[0046] The stainless steel material of the present application can be prepared by various methods, such as chemical vapor deposition, ion sputtering, or controlled sputtering. The specific preparation process of the stainless steel material of the present application is described below.

[0047] Before describing the preparation method of the stainless steel material of the present application, the preparation device involved in the method is first described.

[0048] Figure 2 A schematic diagram of the preparation device of the stainless steel material of the present application is shown in Figure 2 The preparation device includes a high-temperature tube furnace 201, a gas passage 202, an electrode 203, and a metal plate with catalytic activity 204. The high-temperature tube furnace 201 is of a closed structure, with the gas passage 202 arranged on one side. The electrode 203 includes a positive electrode and a negative electrode, wherein the positive electrode can be connected to the metal plate with catalytic activity 204 installed in the high-temperature tube furnace 201, and the negative electrode can be connected to the second stainless steel substrate 205 to be treated.

[0049] The metal plate with catalytic activity can be made of copper, nickel, or other metal materials, preferably a copper plate.

[0050] The second stainless steel substrate 205 to be treated is a common stainless steel material in the prior art, such as type 304, type 317, type 316, type 347, type 410, etc.

[0051] Based on the above preparation device, Figure 3 A flow chart of the preparation method of the stainless steel material of the present application is shown in Figure 3 The method includes:

[0052] Step 301, place the second stainless steel substrate 205 to be treated in the high-temperature tube furnace 201, and connect it to the negative electrode of the electrode 203; place the metal plate with catalytic activity 204 in the high-temperature tube furnace 201, and connect it to the positive electrode of the electrode 203.

[0053] In this step, the second stainless steel substrate 205 to be treated is placed opposite to the metal plate with catalytic activity 204, so that an electric field can be formed between the two after connecting them with the electrode in the subsequent step.

[0054] Step 302, a protective gas is introduced into the vacuumized high-temperature tube furnace 201 through the gas passage 202 connected with the high-temperature tube furnace 201, and the electrode 203 is turned on.

[0055] In this step, the protective gas is an inert gas such as argon or nitrogen.

[0056] Turning on the electrode 203 can form an electric field between the metal plate 204 and the second stainless steel substrate 205, and the voltage of the electric field can be determined according to actual needs. Generally speaking, under the same conditions, the stronger the electric field voltage, the greater the thickness of the subsequent prepared carburized layer 102, the higher the carbon concentration in the carburized layer 102, and the greater the thickness of the carbon film layer 101. In the present application, the electric field voltage can be greater than or equal to 5V and less than or equal to 380V.

[0057] Step 303, after the temperature in the high-temperature tube furnace 201 reaches a first predetermined temperature value, a reducing gas and a gas flow with carbon source molecules are introduced through the gas passage 202, the carbon source molecules are catalytically cracked to obtain positively charged active carbon groups 206, and the active carbon groups 206 act on the second stainless steel substrate 205 under the action of the electric field.

[0058] In this step, the first predetermined temperature value is the reaction temperature value in the high-temperature tube furnace 201, which is generally greater than or equal to 600℃ and less than or equal to 1000℃. Within this reaction temperature range, the higher the predetermined temperature value, the easier it is to form a carburized layer and a carbon film layer, that is, under the same conditions, the higher the predetermined temperature value, the greater the thickness of the carburized layer 102, the higher the carbon concentration in the carburized layer 102, and the greater the thickness of the carbon film layer 101.

[0059] The carbon source is selected from at least one of gaseous carbon sources (such as methane, ethylene, acetylene), solid carbon sources (such as polyaniline, polystyrene), and liquid carbon sources (such as toluene, benzoic acid, chlorobenzene, ethanol, acetonitrile).

[0060] The reducing gas includes hydrogen, ammonia, etc.

[0061] The positively charged active carbon groups 206 obtained by catalytic cracking of the carbon source molecules at high temperature first penetrate into the surface of the cathode second stainless steel substrate 205 under the action of the electric field to form a carburized layer 102 with a thickness of several nanometers to several hundred nanometers; as the carburizing process proceeds, the carbon atoms in the carburized layer 102 reach saturation, and the active carbon groups that continue to bombard the surface of the second stainless steel substrate 205 under the action of the electric field form a dense carbon protective layer with a vertical structure on the surface, which is the carbon film layer 101. The negatively charged non-carbon groups obtained by catalytic cracking of the carbon source molecules at high temperature are discharged as waste products.

[0062] The concentration of carbon source molecules in the gas flow is related to the ease of forming the carburized layer and the carbon film layer. The higher the concentration of carbon source molecules, the easier it is to form the carburized layer and the carbon film layer. That is, under the same conditions, the higher the concentration of carbon source molecules, the greater the thickness of the carburized layer 102, the higher the carbon concentration in the carburized layer 102, and the greater the thickness of the carbon film layer 101.

[0063] Step 304: When the reaction time reaches the first termination condition, stop the gas flow with carbon source molecules from being introduced into the high-temperature tube furnace 201, and disconnect the electrode 203.

[0064] The positively charged active carbon groups continuously bombard the second stainless steel substrate 205 under the action of the electric field. Within a certain reaction time, the second stainless steel substrate 205 continuously changes, including the penetration of carbon elements on its surface and the covering of a carbon film. This certain reaction time is the first termination condition (the value range of the first termination condition is 1 min to 120 min). At this time, the gas flow with carbon source molecules can be stopped from being introduced into the high-temperature tube furnace 201, and the electrode 203 can be disconnected, thereby stopping the process of generating positively charged active carbon groups and bombarding the stainless steel substrate.

[0065] Step 305: Stop the working process of the high-temperature tube furnace 201, and after cooling, obtain the first stainless steel substrate 103 including the carburized layer 102 on the surface and the carbon film layer 101 covering the surface of the first stainless steel substrate 103.

[0066] In this step, the heating process of the high-temperature tube furnace 201 is stopped, so that the temperature in the furnace gradually decreases, while the protective gas and the reducing gas are still transmitted to the high-temperature tube furnace 201 through the gas passage 202; the product continuously bombarded by the active carbon groups is naturally cooled, and finally the required stainless steel material is obtained, which includes the first stainless steel substrate 103 including the carburized layer 102 on the surface and the carbon film layer 101 covering the surface of the first stainless steel substrate 103.

[0067] The carbon film layer 101 in the stainless steel material generally contains both graphite-like structure (sp2) and diamond-like structure (sp3).

[0068] The preparation method of the stainless steel material of the present application can form a carburized layer inside the surface of the stainless steel substrate by continuously bombarding the surface of the stainless steel substrate with active carbon groups, and cover the outer surface of the stainless steel substrate with a carbon film layer. The presence of the carburized layer can not only improve the hardness, wear resistance and fatigue resistance of the stainless steel, but also improve its corrosion resistance. The carbon content of the carburized layer changes in a gradient from the saturation state of the substrate surface to different depths of the carburized layer below, and there is no obvious boundary between the carburized layer and the substrate. Therefore, the carburized layer will not fall off when thermal expansion or mechanical deformation occurs. At the same time, the phenomenon of coating falling off due to the difference in thermal expansion coefficient between the stainless steel and the corrosion-resistant coating can be eliminated, and the potential difference between them can also slow down the corrosion.

[0069] Based on any of the above embodiments, in the present embodiment, between the steps 4) and 5), the method further comprises:

[0070] The temperature in the furnace of the high-temperature tubular furnace 201 is reduced to a second predetermined temperature value, and the temperature in the furnace is maintained at the second predetermined temperature value until the reaction time reaches a second termination condition; wherein the second predetermined temperature value is lower than the first predetermined temperature value.

[0071] In this step, the protective gas and the reducing gas continue to be input into the high-temperature tubular furnace 201 through the gas channel 202. At the same time, the temperature in the furnace of the high-temperature tubular furnace 201 is reduced from the previously higher first predetermined temperature value to a lower second predetermined temperature value, such as 1000℃ for the first predetermined temperature value and 600℃ for the second predetermined temperature value, and the second temperature value in the furnace is maintained for a period of time to make the reaction time reach the second termination condition, such as 30 minutes, and then the working process of the high-temperature tubular furnace 201 is stopped, so that the temperature in the furnace gradually decreases, and at the same time the protective gas and the reducing gas continue to be transmitted into the high-temperature tubular furnace 201 through the gas channel 202, and after cooling, the required stainless steel material with high corrosion resistance can be obtained.

[0072] The above-mentioned second termination condition is greater than or equal to 10 minutes and less than or equal to 90 minutes.

[0073] In the present embodiment, on the basis of the stainless steel material prepared in the previous embodiment, the obtained stainless steel material is subjected to heat preservation treatment at a second predetermined temperature value lower than the first predetermined temperature value. This can increase the proportion of graphite-like structure (sp2) in the carbon film layer 101 (i.e. reduce the proportion of diamond-like structure (sp3) in the carbon film layer 101), thereby adjusting the resistivity of the surface of the stainless steel and realizing the application of the stainless steel in conductive and non-conductive environments. Generally, the longer the time for heat preservation treatment of the stainless steel material at the second predetermined temperature value, the higher the proportion of graphite-like structure (sp2) in the carbon film layer 101.

[0074] Further optimization of temperature, gas pressure, atmosphere composition and catalytic conditions can achieve carbon atom docking, local diffusion and crystallization, and complete the growth of graphene. The application of stainless steel in the fields of bipolar plate, alkali resistance, and strong acid and strong alkali metal resistance is broadened.

[0075] The application will be further described below in conjunction with specific examples.

[0076] Example 1

[0077] The high-temperature tube furnace was vacuumed to 0.5 Pa, 50 sccm of argon gas was introduced as a protective gas, and a copper plate and the second stainless steel substrate to be treated were connected to the positive and negative electrodes of an electric field with a voltage of 12 V; then the high-temperature tube furnace was heated to 1000℃, 200 sccm of ethanol vapor was introduced as a carbon source, and 20 sccm of hydrogen gas was introduced as a reducing gas, and the reaction time was 30 min.

[0078] Under the action of the electric field, part of the active carbon groups with positive charges generated by the pyrolysis penetrated into the interior of the second stainless steel substrate, and part of them deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction, the carbon source was turned off. Under the condition of argon and hydrogen, the reaction product was taken out after natural cooling to room temperature, and the required stainless steel material was obtained. The stainless steel material includes a first stainless steel substrate including a carburized layer on the surface and a carbon film layer covering the surface of the first stainless steel substrate.

[0079] The obtained stainless steel material was characterized. Figure 4 It is a scanning electron microscope image of the surface of the stainless steel material obtained in Example 1. Figure 5 It is an EDS spectrum of the stainless steel material obtained in Example 1. Figure 5 It is a Raman spectrum of the stainless steel material obtained in Example 1. The following Table 1 lists the weight percentage and average mass fraction (Wt% Sigma) of the relevant elements obtained from the EDS spectrum of the stainless steel material obtained in Example 1.

[0080] Element wt. % Wt % Sigma C 7.38 0.34 O 19.07 0.16 Si 1.19 0.04 Cr 39.50 0.24 Mn 8.11 0.16 Fe 21.44 0.20 Ni 2.25 0.14 Mo 0.76 0.10 Al 0.19 0.03 Cl 0.10 0.03

[0081] Table 1

[0082] As can be seen from Figure 4 , the carbon layer in the stainless steel material obtained in Example 1 exists, and the EDS characterization shows that the carbon content increases to 34 Wt% (see Table 1), and the Raman spectrum (such as Figure 5 ) characterization shows that the carbon layer obtained under this condition is mainly amorphous carbon (SP3). The prepared stainless steel sample with coating was subjected to corrosion resistance detection. The corrosion current density reached 5.93×10 -7 μA / cm 2 , which has good corrosion resistance.

[0083] Example 2

[0084] The high-temperature tube furnace was vacuumed to 0.5 Pa, 50 sccm of argon was introduced as a protective gas, and a metal copper plate and a second stainless steel substrate to be treated were connected to the positive and negative electrodes of an electric field with a voltage of 12 V, respectively. Then, the high-temperature tube furnace was heated to 1000℃, 200 sccm of ethanol vapor was introduced as a carbon source, and 20 sccm of hydrogen was introduced as a reducing gas. The reaction time was 30 min.

[0085] Under the action of the electric field, part of the cracked active carbon groups with positive charges penetrated into the interior of the second stainless steel substrate, and part of the cracked active carbon groups with positive charges deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction was completed, the carbon source was turned off. The temperature of the tube furnace was reduced to 600℃ under the condition of argon and hydrogen, the reaction product was kept at this temperature for 30 min, and then naturally cooled to room temperature. The desired stainless steel material was obtained.

[0086] The obtained stainless steel material was characterized. Figure 6 The Raman spectrum of the stainless steel material obtained in Example 2 is shown in FIG. 2. It can be seen that the sp2 / sp3 ratio of the carbon layer obtained under this condition is larger than that of the stainless steel material obtained in Example 1. Figure 6 The prepared stainless steel sample with a coating layer was subjected to corrosion resistance detection. The stable corrosion current density reached 3.93×10 -7 μA / cm2, which has good corrosion resistance.

[0087] Example 3

[0088] The high-temperature tube furnace was vacuumed to 0.5 Pa, 50 sccm of argon was introduced as a protective gas, and a metal copper plate and a second stainless steel substrate to be treated were connected to the positive and negative electrodes of an electric field with a voltage of 12 V, respectively. Then, the high-temperature tube furnace was heated to 1000℃, 200 sccm of ethanol vapor was introduced as a carbon source, and 20 sccm of hydrogen was introduced as a reducing gas. The reaction time was 30 min.

[0089] Under the action of the electric field, part of the cracked active carbon groups with positive charges penetrated into the interior of the second stainless steel substrate, and part of the cracked active carbon groups with positive charges deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction was completed, the carbon source was turned off. The temperature of the tube furnace was reduced to 600℃ under the condition of argon and hydrogen, the reaction product was kept at this temperature for 30 min, and then naturally cooled to room temperature. The desired stainless steel material was obtained.

[0090] The obtained stainless steel material was characterized. Figure 7 The Raman spectrum of the stainless steel material obtained in Example Three is shown in Figure 3. From the spectrum, it can be seen that the carbon layer obtained under the condition is a graphene film of crystalline carbon sp2 structure. Figure 7 The prepared stainless steel sample with coating was subjected to corrosion resistance detection. The stable corrosion current density reached 1.84 x 10 -7 μA / cm2, which has good corrosion resistance.

[0091] Example Four

[0092] The high-temperature tube furnace was vacuumed to 1 Pa, 50 sccm of nitrogen gas was introduced as a protective gas, and the metal copper plate and the second stainless steel substrate to be treated were connected to the positive and negative electrodes of an electric field with a voltage of 220 V, respectively. Then the high-temperature tube furnace was heated to 600°C, 200 sccm of methane steam was introduced as a carbon source, and 20 sccm of hydrogen gas was introduced as a reducing gas, and the reaction time was 120 min.

[0093] Under the action of the electric field, part of the active carbon groups with positive charges penetrated into the interior of the second stainless steel substrate, and part of them deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction was completed, the carbon source was turned off. The reaction product was taken out after natural cooling to room temperature in the presence of nitrogen and hydrogen, and the required stainless steel material was obtained. The stainless steel material includes a first stainless steel substrate with a carburized layer on the surface and a carbon film layer covering the surface of the first stainless steel substrate.

[0094] Example Five

[0095] The high-temperature tube furnace was vacuumed to 1 Pa, 50 sccm of nitrogen gas was introduced as a protective gas, and the metal copper plate and the second stainless steel substrate to be treated were connected to the positive and negative electrodes of an electric field with a voltage of 380 V, respectively. Then the high-temperature tube furnace was heated to 800°C, 200 sccm of gas containing polystyrene was introduced as a carbon source, and 20 sccm of hydrogen gas was introduced as a reducing gas, and the reaction time was 1 min.

[0096] Under the action of the electric field, part of the active carbon groups with positive charges penetrated into the interior of the second stainless steel substrate, and part of them deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction was completed, the carbon source was turned off. The reaction product was taken out after natural cooling to room temperature in the presence of nitrogen and hydrogen, and the required stainless steel material was obtained. The stainless steel material includes a first stainless steel substrate with a carburized layer on the surface and a carbon film layer covering the surface of the first stainless steel substrate.

[0097] Example Six

[0098] The high-temperature tube furnace is vacuumed to 1 Pa, 50 sccm nitrogen is introduced as a protective gas, and the metal copper plate and the second stainless steel substrate to be treated are connected to the positive and negative electrodes of an electric field with a voltage of 380 V; the high-temperature tube furnace is heated to 800 ℃, 200 sccm of a gas containing polystyrene is introduced as a carbon source, and 30 sccm of hydrogen is introduced as a reducing gas, and the reaction time is 60 min.

[0099] Under the action of the electric field, part of the active carbon groups with positive charges generated by the pyrolysis penetrates into the interior of the second stainless steel substrate, and part of the active carbon groups with positive charges generated by the pyrolysis is deposited on the surface of the second stainless steel substrate to form a carbon film with corrosion resistance. After the reaction is completed, the carbon source is turned off. The temperature of the tube furnace is reduced to 500 ℃ under the condition of argon and hydrogen, the reaction product is kept at the temperature for 90 min, and then is taken out after being naturally cooled to room temperature, to obtain the required stainless steel material. The stainless steel material includes the first stainless steel substrate including a carburized layer on the surface and the carbon film layer covering the surface of the first stainless steel substrate.

[0100] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing a stainless steel material, characterized by, The method comprises: Step 1), placing the second stainless steel substrate (205) to be treated in a high-temperature tube furnace (201) and connecting it to the negative electrode of an electrode (203); placing a metal plate (204) with catalytic activity in the high-temperature tube furnace (201) and connecting it to the positive electrode of the electrode (203); Step 2), introducing a protective gas into the vacuumized high-temperature tube furnace (201) through a gas channel (202) connected to the high-temperature tube furnace (201) and turning on the electrode (203); Step 3), after the temperature in the high-temperature tube furnace (201) reaches a first predetermined temperature value, a reducing gas and a gas stream containing carbon source molecules are introduced through the gas channel (202), the carbon source molecules are catalytically cracked to obtain positively charged active carbon groups (206); the active carbon groups (206) act on the second stainless steel substrate (205) under the action of an electric field; wherein the first predetermined temperature value is greater than or equal to 600°C and less than or equal to 1000°C; the voltage value of the electric field is greater than or equal to 5V and less than or equal to 380V; Step 4), when the reaction time reaches a first termination condition, stop introducing the gas stream containing carbon source molecules into the high-temperature tube furnace (201) and disconnect the electrode (203); wherein the first termination condition is greater than or equal to 1 minute and less than or equal to 120 minutes; Step 5), stop the working process of the high-temperature tube furnace (201), and after cooling, obtain a first stainless steel substrate (103) including a carburized layer (102) and a carbon film layer (101) covering the surface of the first stainless steel substrate (103).

2. The method of producing a stainless steel material according to claim 1, characterized by, Between the step 4) and step 5), the method further comprises: Lowering the temperature in the high-temperature tube furnace (201) to a second predetermined temperature value and keeping the temperature in the furnace at the second predetermined temperature value until the second predetermined temperature value maintains for a second termination condition; wherein the second predetermined temperature value is lower than the first predetermined temperature value.

3. The method of producing a stainless steel material according to claim 2, characterized by, The second termination condition is greater than or equal to 10 minutes and less than or equal to 90 minutes.

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