High alloy steel gas nitriding catalyst precursor solution as well as preparation method and catalytic nitriding method thereof

Abstract

The invention provides a high alloy steel gas nitriding catalyst precursor solution as well as a preparation method and a catalytic nitriding method thereof, and belongs to the technical field of nitriding. The high alloy steel gas nitriding catalyst precursor solution provided by the invention comprises a first precursor solution and a second precursor solution, the first precursor solution comprises the following components: rare earth metal salt, chromium salt, manganese salt, cobalt salt, nickel salt, citric acid and a solvent; the second precursor solution comprises the following components: chlorate, citric acid and a solvent. The first precursor solution and the second precursor solution have a synergistic effect, a compact passivation film on the surface of the high alloy steel is damaged through chloride ion chemical erosion in the nitriding heating process and is prevented from being regenerated in the nitriding process, catalyst components directly act on a material matrix, and the uniformity of a nitriding layer is remarkably improved; the first precursor solution can generate a perovskite type rare earth oxide film in situ, and efficient gas nitriding of high alloy steel can be realized, so that the thickness of a nitriding layer is increased.

Description

Technical Field

[0001] This invention belongs to the field of nitriding technology, specifically relating to a high-alloy steel gas nitriding catalyst precursor solution, its preparation method, and a catalytic nitriding method. Background Technology

[0002] Nitriding is a common surface strengthening technique that involves placing steel parts in an active nitrogen medium and holding them at a certain temperature, allowing nitrogen to permeate their surface. This process gives the steel parts higher hardness, fatigue strength, and wear resistance, and the formation of a dense compound layer provides excellent corrosion resistance. It is widely used for parts requiring minimal deformation, high dimensional stability, and good wear resistance. The nitriding process is primarily gas nitriding, and its ease of operation and low cost make it suitable for industrial application.

[0003] Currently, to obtain thicker nitrided layers, gas nitriding processes typically employ high-temperature or long-duration nitriding, but both of these methods degrade the internal properties of the material and consume significant amounts of energy. Surface activation, by improving gas nitriding kinetics and increasing the nitriding rate, has gradually become the optimal choice for deep nitriding. From the perspective of increasing the nitriding rate, surface activation can be achieved through two methods: physical or chemical. Cathodic sputtering or surface nano-sizing, as physical pretreatments, has proven to be effective methods for increasing the nitriding rate. Chemical pretreatments, such as catalytic nitriding, achieve rapid diffusion of nitrogen atoms. While these methods have increased the nitrided layer depth to some extent, the effect of catalytic nitriding is quite limited. Therefore, how to improve catalytic nitriding to increase the depth of the nitrided layer has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a high-alloy steel gas nitriding catalyst precursor solution, its preparation method, and a catalytic nitriding method. Using the high-alloy steel gas nitriding catalyst precursor solution provided by this invention for catalytic nitriding can increase the depth of the nitrided layer.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a high-alloy steel gas nitriding catalyst precursor solution, comprising a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents; The second precursor solution comprises the following components: chloride salt, citric acid, and solvent.

[0006] Preferably, with the volume of the high-alloy steel gas nitriding catalyst precursor solution as 100%, the volume percentage of the first precursor solution is 70.0~97.0%, and the volume percentage of the second precursor solution is 3.0~30.0%.

[0007] Preferably, the rare earth metal salt is lanthanum nitrate, the chromium salt is chromium nitrate, the manganese salt is manganese nitrate, the cobalt salt is cobalt nitrate, and the nickel salt is nickel nitrate. The molar ratio of the rare earth metal salt, chromium salt, manganese salt, cobalt salt, nickel salt and citric acid is (3~5):(1~2):(1~2):(1~2):(1~2):(9~11).

[0008] Preferably, the chloride salt includes sodium chloride, lanthanum chloride, or ferric chloride.

[0009] Preferably, when the chloride salt is sodium chloride, the molar ratio of sodium chloride to citric acid is (11~13):(4~6).

[0010] Preferably, when the chloride salt is lanthanum chloride, the molar ratio of lanthanum chloride to citric acid is (3~5):(4~6); when the chloride salt is ferric chloride, the molar ratio of ferric chloride to citric acid is (3~5):(4~6).

[0011] The present invention also provides a method for preparing the high-alloy steel gas nitriding catalyst precursor solution described in the above technical solution, comprising the following steps: Rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents are mixed to obtain a first precursor solution; The chloride salt, citric acid, and solvent are mixed to obtain the second precursor solution; The first precursor solution and the second precursor solution are mixed to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0012] The present invention also provides a catalytic nitriding method, comprising: The high-alloy steel gas nitriding catalyst precursor solution described in the above technical solution or the high-alloy steel gas nitriding catalyst precursor solution prepared by the preparation method described in the above technical solution is coated onto the substrate surface for nitriding.

[0013] Preferably, the flow rate of NH3 used in the nitriding is 0.1~0.2 L / min.

[0014] Preferably, the nitriding time is 2 to 8 hours.

[0015] This invention provides a precursor solution for a gas nitriding catalyst on high-alloy steel, comprising a first precursor solution and a second precursor solution. The first precursor solution comprises rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and a solvent. The second precursor solution comprises chloride salts, citric acid, and a solvent. The first and second precursor solutions (passivation film breaker) of this invention work synergistically to destroy the dense passivation film on the surface of high-alloy steel through chloride ion chemical etching during the nitriding heating process, preventing its regeneration during nitriding. This allows the catalyst components to interact directly with the material matrix, significantly improving the uniformity of the nitrided layer. Furthermore, the first precursor solution can generate a perovskite-type rare earth oxide film in situ, enabling efficient gas nitriding of high-alloy steel. This provides important technical support for rapid deep nitriding strengthening of high-alloy steel surfaces, thereby increasing the thickness of the nitrided layer. Experimental results show that using the gas nitriding catalyst precursor solution provided by this invention, the thickness of the nitrided layer is 37.28~234.85 μm. Attached Figure Description

[0016] Figure 1 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 2; Figure 2 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 1 is shown. Figure 3 The microhardness curves of the nitrided layer prepared in Application Example 2 and the nitrided layer prepared in Application Example 1 are shown in cross-sectional view. Figure 4 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 4; Figure 5 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 2 is shown. Figure 6 The microhardness curves of the cross section of the nitrided layer prepared in Example 4 and the nitrided layer prepared in Example 2 are shown. Figure 7 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 10; Figure 8 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 3 is shown. Figure 9 The cross-sectional microhardness curves are shown for the nitrided layer prepared in Application Example 10 and the nitrided layer prepared in Comparative Application Example 3. Detailed Implementation

[0017] This invention provides a high-alloy steel gas nitriding catalyst precursor solution, comprising a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents; The second precursor solution comprises the following components: chloride salt, citric acid, and solvent.

[0018] The present invention does not have any special limitation on the source of the components, and commercially available products known to those skilled in the art can be used.

[0019] In this invention, the high-alloy steel gas nitriding catalyst precursor solution includes a first precursor solution; the first precursor solution includes the following components: rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and a solvent. In this invention, the first precursor solution can generate perovskite-type rare earth oxide films in situ, enabling efficient gas nitriding of high-alloy steel. This provides important technical support for rapid deep nitriding strengthening of high-alloy steel surfaces, thereby increasing the thickness of the nitrided layer.

[0020] In this invention, the rare earth metal salt is preferably lanthanum nitrate; the chromium salt is preferably chromium nitrate; the manganese salt is preferably manganese nitrate; the cobalt salt is preferably cobalt nitrate; and the nickel salt is preferably nickel nitrate. The molar ratio of the rare earth metal salt, chromium salt, manganese salt, cobalt salt, nickel salt, and citric acid is preferably (3~5):(1~2):(1~2):(1~2):(1~2):(9~11), more preferably 4:1:1:1:1:10. This invention utilizes nitrates to form perovskites. By limiting the molar ratio of the rare earth metal salt, chromium salt, manganese salt, cobalt salt, nickel salt, and citric acid to the above range, the formation of tetradiocene-type rare earth oxides can be promoted, thereby further improving the catalytic nitriding effect. Citric acid is a metal ion chelating agent that can promote the formation of perovskites.

[0021] In this invention, the purity of the rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, and citric acid is preferably analytical grade.

[0022] In this invention, the solvent is preferably water. There is no particular limitation on the amount of water used, as long as the required concentration of the first precursor solution is obtained.

[0023] In this invention, the concentration of rare earth metal salt in the first precursor solution is preferably 0.3~0.5 mol / L, more preferably 0.4 mol / L.

[0024] In this invention, the high-alloy steel gas nitriding catalyst precursor solution includes a second precursor solution; the second precursor solution includes the following components: chloride salt, citric acid, and solvent. In this invention, during the nitriding heating process, the dense passivation film on the surface of the high-alloy steel is destroyed by chloride ion chemical etching, and its regeneration during the nitriding process is prevented, allowing the catalyst components to directly interact with the material matrix, significantly improving the uniformity of the nitrided layer.

[0025] In this invention, the chloride salt preferably includes sodium chloride, lanthanum chloride, or ferric chloride; when the chloride salt is sodium chloride, the molar ratio of sodium chloride to citric acid is preferably (11~13):(4~6), more preferably 12:5. Limiting the molar ratio of sodium chloride to citric acid within the above range further improves the nitriding effect.

[0026] In this invention, when the chloride salt is lanthanum chloride, the molar ratio of lanthanum chloride to citric acid is preferably (3~5):(4~6), more preferably 4:5; when the chloride salt is ferric chloride, the molar ratio of ferric chloride to citric acid is preferably (3~5):(4~6), more preferably 4:5. By limiting the molar ratios of lanthanum chloride and citric acid, and ferric chloride and citric acid, to the above ranges, this invention can further improve the nitriding effect.

[0027] In this invention, the purity of the chloride salt and citric acid is preferably analytical grade.

[0028] In this invention, the solvent is preferably water. There is no particular limitation on the amount of water used, as long as the required concentration of the second precursor solution is obtained.

[0029] In this invention, the concentration of the second precursor solution is preferably 0.7~0.9 mol / L, more preferably 0.8 mol / L. In this invention, the concentration of the second precursor solution is the concentration of chloride salt in this solution.

[0030] In this invention, with the volume of the high-alloy steel gas nitriding catalyst precursor solution as 100%, the volume percentage of the first precursor solution is preferably 70.0% to 97.0%; and the volume percentage of the second precursor solution is preferably 3.0% to 30.0%. This invention optimizes the catalytic effect by limiting the volume percentages of the first and second precursor solutions within the above ranges.

[0031] In one embodiment, the volume percentage of the first precursor solution can be 71.0%, 72.0%, 73.0%, 74.0%, 75.0%, 76.0%, 77.0%, 78.0%, 79.0%, 80.0%, 81.0%, 82.0%, 83.0%, 84.0%, 85.0%, 86.0%, 87.0%, 88.0%, 89.0%, 90.0%, 91.0%, 92.0%, 93.0%, 94.0%, 95.0%, or 96.0%.

[0032] In one embodiment, the volume percentage of the second precursor solution can be 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0%, 21.0%, 22.0%, 23.0%, 24.0%, 25.0%, 26.0%, 27.0%, 28.0%, or 29.0%.

[0033] The first precursor solution and the second precursor solution (passivation film breaker) of this invention work synergistically to destroy the dense passivation film on the surface of high alloy steel through chloride ion chemical erosion during the nitriding heating process and prevent its regeneration during nitriding. This allows the catalyst components to interact directly with the material matrix, significantly improving the uniformity of the nitrided layer. Furthermore, the first precursor solution can generate perovskite-type rare earth oxide films in situ, enabling efficient gas nitriding of high alloy steel. This provides important technical support for rapid deep nitriding strengthening of the surface of high alloy steel, thereby increasing the thickness of the nitrided layer.

[0034] This invention achieves a significant improvement in catalytic efficiency. Under normal pressure and low gas flow conditions, with the same nitriding time, the thickness of the nitrided layer with the precursor solution is increased by 30-100% compared to the sample without catalyst. This avoids the decline in the internal properties of the matrix material caused by increasing the temperature and extending the nitriding time, while saving a lot of energy and gas.

[0035] The gas nitriding catalyst precursor solution for high alloy steel provided by this invention will form a perovskite-type rare earth oxide film in situ during the nitriding heating process. Gas nitriding can be carried out under normal pressure and low gas flow rate, which can realize efficient gas nitriding of high alloy steel and provide important technical support for rapid deep nitriding strengthening of high alloy steel surface.

[0036] Compared with conventional gas nitriding, this invention significantly improves nitriding efficiency, and catalytic nitriding is carried out at low gas flow rates, which has the advantages of energy saving, environmental protection and gas conservation.

[0037] The present invention also provides a method for preparing the high-alloy steel gas nitriding catalyst precursor solution described in the above technical solution, comprising the following steps: Rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents are mixed to obtain a first precursor solution; The chloride salt, citric acid, and solvent are mixed to obtain the second precursor solution; The first precursor solution and the second precursor solution are mixed to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0038] The present invention mixes rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid and solvents to obtain a first precursor solution.

[0039] The present invention does not impose any special limitations on the operation of mixing the rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid and solvents; any technical solution for preparing the mixture well known to those skilled in the art can be used.

[0040] The present invention mixes chloride salt, citric acid and solvent to obtain a second precursor solution.

[0041] The present invention does not have any special limitations on the operation of mixing the chloride salt, citric acid and solvent, and any technical solution for preparing the mixture well known to those skilled in the art can be used.

[0042] After obtaining the first precursor solution and the second precursor solution, the present invention mixes the first precursor solution and the second precursor solution to obtain a high alloy steel gas nitriding catalyst precursor solution.

[0043] The present invention does not have any special limitations on the operation of mixing the first precursor solution and the second precursor solution; any technical solution for preparing the mixture well known to those skilled in the art can be used.

[0044] The preparation method provided by this invention simplifies the process complexity and enhances the repeatability of the process.

[0045] The present invention also provides a catalytic nitriding method, comprising: The high-alloy steel gas nitriding catalyst precursor solution described in the above technical solution or the high-alloy steel gas nitriding catalyst precursor solution prepared by the preparation method described in the above technical solution is coated onto the substrate surface for nitriding.

[0046] In this invention, the coating is preferably performed using a spin coating method. This invention does not impose any special limitations on the operation of the spin coating method; any operation well-known to those skilled in the art can be used.

[0047] In this invention, the matrix is ​​preferably high-alloy steel. This invention does not impose any specific limitations on the composition of the high-alloy steel; any high-alloy steel well-known to those skilled in the art can be used.

[0048] After coating is completed, the product obtained by coating is preferably dried; the drying time is preferably 10-15 minutes.

[0049] In this invention, the nitriding temperature is preferably 500~700℃, more preferably 600℃; when the substrate coated with the high alloy steel gas nitriding catalyst precursor solution is heated to 300℃, the nitriding medium NH3 is preferably introduced; the flow rate of NH3 used for nitriding is preferably 0.1~0.2L / min.

[0050] The present invention does not impose any special limitation on the heating rate; the required temperature can be reached by using an operation known to those skilled in the art.

[0051] In this invention, the nitriding time is preferably 2 to 8 hours. As one embodiment, the nitriding time can be 3 hours, 4 hours, 5 hours, 6 hours, or 7 hours.

[0052] After nitriding is completed, the product obtained by nitriding is preferably cooled; the cooling is preferably furnace cooling. The present invention does not have any particular limitations on the furnace cooling operation; any operation well known to those skilled in the art can be used to cool to room temperature.

[0053] The catalytic nitriding method provided by this invention has a simple process.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Unless otherwise specified, the experimental methods used in the examples are conventional methods, and the materials and reagents used are commercially available.

[0056] The high-alloy steel used in the examples is 1Cr11Ni2W2MoV heat-resistant steel, with the following composition by mass percentage: C 0.12%, Si 0.260%, Mn 0.33%, Cr 11.20%, Ni 1.60%, W 1.80%, Mo 0.46%, V 0.22%, with the balance being Fe and other unavoidable impurities.

[0057] Example 1 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: lanthanum chloride, citric acid, and distilled water; The lanthanum chloride and citric acid were of analytical grade. The molar ratio of lanthanum chloride to citric acid is 4:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; 0.02 mol of lanthanum chloride and 0.025 mol of citric acid were dissolved in 25 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 97.0% and 3.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0058] Application Example 1 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 1 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 2 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 37.28 μm using a metallographic microscope.

[0059] Application Example 2 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 1 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3 nitriding medium was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 128 μm using a metallographic microscope.

[0060] Comparative Application Example 1 Based on Application Example 2, the coating of the high-alloy steel gas nitriding catalyst precursor solution was omitted, while other conditions remained unchanged. The thickness of the nitrided layer was measured to be 63 μm using a metallographic microscope.

[0061] Figure 1 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 2; Figure 2 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 1 is shown.

[0062] from Figure 1 and 2 It can be seen that the high-alloy steel gas nitriding catalyst precursor solution prepared in Example 1 can increase the thickness of the nitriding layer.

[0063] Figure 3 The cross-sectional microhardness curves are shown for the nitrided layer prepared in Application Example 2 and the nitrided layer prepared in Application Example 1.

[0064] from Figure 3 It can be seen that the thickness of the nitriding layer after coating with catalyst precursor solution is about 200 μm (the thickness of the nitriding layer measured by hardness method is deeper than that measured by metallographic method), while the thickness of the nitriding layer without catalyst precursor solution is about 100 μm. The nitriding layer depth after coating with catalyst precursor solution is significantly improved by 100% compared with that without catalyst precursor solution.

[0065] Example 2 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: lanthanum chloride, citric acid, and distilled water; The lanthanum chloride and citric acid were of analytical grade. The molar ratio of lanthanum chloride to citric acid is 4:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; 0.02 mol of lanthanum chloride and 0.025 mol of citric acid were dissolved in 25 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 92.0% and 8.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0066] Application Example 3 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 2 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 2 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 69.18 μm using a metallographic microscope.

[0067] Application Example 4 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 2 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3 nitriding medium was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 98 μm using a metallographic microscope.

[0068] Comparative Application Example 2 Based on Application Example 4, the coating of the high-alloy steel gas nitriding catalyst precursor solution was omitted, while other conditions remained unchanged. The thickness of the nitrided layer was measured to be 36 μm using a metallographic microscope.

[0069] Figure 4 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 4; Figure 5 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 2 is shown.

[0070] from Figure 4 and 5 It can be seen that the high-alloy steel gas nitriding catalyst precursor solution prepared in Example 2 can increase the thickness of the nitriding layer.

[0071] Figure 6 The cross-sectional microhardness curves are shown for the nitrided layer prepared in Example 4 and the nitrided layer prepared in Example 2 for comparison.

[0072] from Figure 6 It can be seen that the thickness of the nitriding layer after coating with catalyst precursor solution is about 120 μm, while the thickness of the nitriding layer without catalyst precursor solution is about 50 μm. The nitriding layer depth after coating with catalyst precursor solution is also significantly improved by 140% compared with that without catalyst precursor solution.

[0073] Application Example 5 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 2 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 8 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 233.63 μm using a metallographic microscope.

[0074] Example 3 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: lanthanum chloride, citric acid, and distilled water; The lanthanum chloride and citric acid were of analytical grade. The molar ratio of lanthanum chloride to citric acid is 4:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; 0.02 mol of lanthanum chloride and 0.025 mol of citric acid were dissolved in 25 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 85.0% and 15.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0075] Application Example 6 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 3 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3 nitriding medium was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 2 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 87.52 μm using a metallographic microscope.

[0076] Application Example 7 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 3 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 131.88 μm using a metallographic microscope.

[0077] Application Example 8 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 3 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3 nitriding medium was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 8 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 234.85 μm using a metallographic microscope.

[0078] Example 4 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: sodium chloride, citric acid, and distilled water; The sodium chloride and citric acid were of analytical grade. The molar ratio of sodium chloride to citric acid is 12:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; Dissolve 0.06 mol sodium chloride and 0.025 mol citric acid in 75 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 92.0% and 8.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0079] Application Example 9 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 4 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3 nitriding medium was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 74.88 μm using a metallographic microscope.

[0080] Example 5 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: ferric chloride, citric acid, and distilled water; The ferric chloride and citric acid were of analytical grade. The molar ratio of ferric chloride to citric acid is 4:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; 0.02 mol ferric chloride and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 92.0% and 8.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0081] Application Example 10 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 5 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 148 μm using a metallographic microscope.

[0082] Comparative Application Example 3 Based on Application Example 10, the coating of the high-alloy steel gas nitriding catalyst precursor solution was omitted, while other conditions remained unchanged. The thickness of the nitrided layer was measured to be 117 μm using a metallographic microscope.

[0083] Figure 7 A cross-sectional metallographic micrograph of the nitrided layer prepared in Example 10; Figure 8 For comparison, a cross-sectional metallographic micrograph of the nitrided layer prepared in Example 3 is shown.

[0084] from Figure 7 and 8 It can be seen that the high-alloy steel gas nitriding catalyst precursor solution prepared in Example 5 can increase the thickness of the nitriding layer.

[0085] Figure 9 The cross-sectional microhardness curves are shown for the nitrided layer prepared in Application Example 10 and the nitrided layer prepared in Comparative Application Example 3.

[0086] from Figure 9 It can be seen that the thickness of the nitriding layer after coating with catalyst precursor solution is about 160 μm, while the thickness of the nitriding layer without catalyst precursor solution is about 130 μm. The nitriding layer depth is increased by 23% after coating with catalyst precursor solution compared with that without catalyst precursor solution.

[0087] Example 6 A high-alloy steel gas nitriding catalyst precursor solution comprises a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, citric acid, and distilled water; The purity of the lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is analytical grade. The molar ratio of lanthanum nitrate, chromium nitrate, manganese nitrate, cobalt nitrate, nickel nitrate, and citric acid is 4:1:1:1:1:10. The concentration of lanthanum nitrate in the first precursor solution is 0.4 mol / L; The second precursor solution comprises the following components: lanthanum chloride, citric acid, and distilled water; The lanthanum chloride and citric acid were of analytical grade. The molar ratio of lanthanum chloride to citric acid is 4:5; The concentration of the second precursor solution is 0.8 mol / L; The preparation method of the high-alloy steel gas nitriding catalyst precursor solution is as follows: 0.01 mol lanthanum nitrate, 0.0025 mol chromium nitrate, 0.0025 mol manganese nitrate, 0.0025 mol cobalt nitrate, 0.0025 mol nickel nitrate and 0.025 mol citric acid were dissolved in 25 mL of distilled water to obtain the first precursor solution; 0.02 mol of lanthanum chloride and 0.025 mol of citric acid were dissolved in 25 mL of distilled water to obtain the second precursor solution; The first precursor solution and the second precursor solution were mixed evenly at a volume percentage of 70.0% and 30.0% to obtain a high-alloy steel gas nitriding catalyst precursor solution.

[0088] Application Example 11 The high-alloy steel gas nitriding catalyst precursor solution prepared in Example 6 was uniformly coated onto the clean surface of the workpiece sample using a spin-coating method. After drying for 15 minutes, the sample was placed in a vacuum nitriding furnace and heated to 300°C under atmospheric conditions. Once the temperature reached 300°C, NH3, the nitriding medium, was continuously introduced at a flow rate of 0.1 L / min. The temperature was then raised to 600°C, and nitriding was started and timed for 4 hours. The sample was then cooled to room temperature in the nitriding medium within the furnace. The thickness of the nitrided layer was measured to be 143.00 μm using a metallographic microscope.

[0089] pass Figures 1-9 It can be seen that the catalyst precursor solution for high-alloy steel gas nitriding significantly improves the nitriding rate in low-flow-rate gas nitriding at atmospheric pressure. The catalytic gas nitriding method for high-alloy steel can significantly improve the depth and uniformity of the nitrided layer. Compared with conventional gas nitriding, this catalytic nitriding method significantly improves nitriding efficiency, while also offering advantages such as simple operation, energy saving, environmental protection, and gas conservation. It provides important technical support for rapid deep nitriding strengthening of high-alloy steel surfaces.

[0090] As can be seen from the above embodiments, using the high-alloy steel gas nitriding catalyst precursor solution provided by the present invention for catalytic nitriding can increase the depth of the nitrided layer.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-alloy steel gas nitriding catalyst precursor solution, comprising a first precursor solution and a second precursor solution; The first precursor solution comprises the following components: rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents; The second precursor solution comprises the following components: chloride salt, citric acid, and solvent.

2. The high-alloy steel gas nitriding catalyst precursor solution according to claim 1, characterized in that, With the volume of the high-alloy steel gas nitriding catalyst precursor solution as 100%, the volume percentage of the first precursor solution is 70.0~97.0%, and the volume percentage of the second precursor solution is 3.0~30.0%.

3. The high-alloy steel gas nitriding catalyst precursor solution according to claim 1, characterized in that, The rare earth metal salt is lanthanum nitrate, the chromium salt is chromium nitrate, the manganese salt is manganese nitrate, the cobalt salt is cobalt nitrate, and the nickel salt is nickel nitrate. The molar ratio of the rare earth metal salt, chromium salt, manganese salt, cobalt salt, nickel salt and citric acid is (3~5):(1~2):(1~2):(1~2):(1~2):(9~11).

4. The high-alloy steel gas nitriding catalyst precursor solution according to claim 1, characterized in that, The chloride salt includes sodium chloride, lanthanum chloride, or ferric chloride.

5. The method according to claim 4, characterized in that, When the chloride salt is sodium chloride, the molar ratio of sodium chloride to citric acid is (11~13):(4~6).

6. The method according to claim 4, characterized in that, When the chloride salt is lanthanum chloride, the molar ratio of lanthanum chloride to citric acid is (3~5):(4~6); when the chloride salt is ferric chloride, the molar ratio of ferric chloride to citric acid is (3~5):(4~6).

7. A method for preparing the high-alloy steel gas nitriding catalyst precursor solution according to any one of claims 1 to 6, comprising the following steps: Rare earth metal salts, chromium salts, manganese salts, cobalt salts, nickel salts, citric acid, and solvents are mixed to obtain a first precursor solution; The chloride salt, citric acid, and solvent are mixed to obtain the second precursor solution; The first precursor solution and the second precursor solution are mixed to obtain a high-alloy steel gas nitriding catalyst precursor solution.

8. A catalytic nitriding method, comprising: The high-alloy steel gas nitriding catalyst precursor solution according to any one of claims 1 to 6 or the high-alloy steel gas nitriding catalyst precursor solution prepared by the preparation method according to claim 7 is coated onto the substrate surface for nitriding.

9. The catalytic nitriding method according to claim 8, characterized in that, The flow rate of NH3 used in the nitriding process is 0.1~0.2 L / min.

10. The catalytic nitriding method according to claim 8, characterized in that, The nitriding time is 2-8 hours.

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