A gas QPQ post-oxidation blackening agent, its preparation method and application

Abstract

This invention relates to the field of workpiece surface treatment technology, and discloses a gas QPQ post-oxidation blackening agent, its preparation method, and its application. By weight, the gas QPQ post-oxidation blackening agent comprises the following components: 15-30 parts rare earth compounds, 10-15 parts citric acid and / or citrate, 5-15 parts ammonium molybdate, 3-8 parts ammonium chloride, 15-25 parts vitamin C, 10-30 parts formamide, 5-10 parts manganese dioxide, 5-10 parts phosphoric acid, 15-30 parts calcium nitrate, 30-40 parts ethanol, and 5000 parts water. In this invention, the components work together synergistically to ensure that the treated metal products fully meet their requirements for corrosion resistance and color.

Description

Technical Field

[0001] This invention relates to the field of workpiece surface processing technology, and in particular to a gas QPQ post-oxidation blackening agent, its preparation method, and its application. Background Technology

[0002] Gas-based nitrogen-carbon-oxygen co-diffusion treatment, also known as gas-based QPQ, involves placing metal products in a dedicated gas-based QPQ furnace to perform a combined nitrogen, carbon, and oxygen co-diffusion process on the metal surface. Currently, the gas-based QPQ process results in workpieces with a corrosion resistance time of approximately 60 hours in a neutral salt spray test, which is insufficient for the corrosion resistance of metal products in harsh environments. Furthermore, the treated workpiece surface is gray, dark gray, light blackish-gray, or light blackish-blue, but cannot be black. In other words, the current QPQ process does not meet the requirements for both corrosion resistance and color in metal products.

[0003] To meet the above requirements, the metal products after being taken out of the furnace need to undergo a secondary treatment of coupling and oil immersion. However, on the one hand, the metal products need to be immersed in the coupling box for at least 30 minutes during this process, which takes a long time. In addition, a large amount of grease will adhere to the surface of the metal products after immersion, making it very difficult to clean later. On the other hand, the color adhesion of the surface of the metal products after the secondary treatment is poor. When subjected to high-pressure rinsing, the color is washed away, exposing the gray and gray-blue base. Furthermore, the corrosion resistance is also poor.

[0004] Therefore, improving the corrosion resistance and color adhesion performance of metal products is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a gas QPQ post-oxidation blackening agent, its preparation method and application, to solve the defects in the existing gas QPQ process. The existing gas QPQ process often requires a long secondary treatment to meet the requirements of metal products for corrosion resistance and color adhesion. However, after the secondary treatment, a complicated post-cleaning process is required, and the color of the workpiece after the secondary treatment still cannot meet the requirements.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a gaseous QPQ post-oxidation blackening agent, which, by weight, comprises the following components: 15-30 parts of rare earth compound, 10-15 parts of citric acid and / or citrate, 5-15 parts of ammonium molybdate, 3-8 parts of ammonium chloride, 15-25 parts of vitamin C, 10-30 parts of formamide, 5-10 parts of manganese dioxide, 5-10 parts of phosphoric acid, 15-30 parts of calcium nitrate, 30-40 parts of ethanol, and 5000 parts of water.

[0008] Preferably, the rare earth compound is a rare earth chloride and / or a rare earth oxide.

[0009] Preferably, the citrate includes one or more of sodium citrate and potassium citrate.

[0010] On the other hand, the present invention provides a method for preparing the gaseous QPQ post-oxidation blackening agent according to any one of the above claims, comprising the following steps: mixing rare earth compounds, citric acid and / or citrate, ammonium molybdate, ammonium chloride, vitamin C, formamide, manganese dioxide, phosphoric acid, calcium nitrate, ethanol and water to obtain the gaseous QPQ post-oxidation blackening agent.

[0011] Furthermore, the present invention also provides the application of the gaseous QPQ post-oxidation blackening agent described in any of the above claims or the gaseous QPQ post-oxidation blackening agent prepared by the above method in gaseous nitrogen, carbon, and oxygen composite treatment.

[0012] Preferably, the application of the gaseous QPQ post-oxidation blackening agent in the gaseous nitrogen, carbon, and oxygen composite treatment includes the following steps:

[0013] (1) Place the workpiece to be treated in a co-diffusion furnace and perform nitriding and carbonization treatment to obtain a nitrided workpiece;

[0014] (2) The gas QPQ post-oxidation blackening agent is added into the co-diffusion furnace for drip diffusion treatment to obtain the treated workpiece.

[0015] Preferably, step (2) specifically includes the following steps:

[0016] A. After lowering the temperature in the co-infiltration furnace to 560℃, maintain the temperature for 60-90 minutes. During the constant temperature maintenance, add gaseous QPQ followed by oxidation blackening agent into the co-infiltration furnace at a rate of 150-180 drops / minute.

[0017] B. Continue to cool the temperature inside the co-diffusion furnace from 560℃ to 380℃. During the cooling process, add gaseous QPQ post-oxidation blackening agent into the co-diffusion furnace at a rate of 40-80 drops / minute.

[0018] Preferably, in step B, during the cooling process, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a decreasing rate, specifically as follows: when the temperature in the co-diffusion furnace drops from 560°C to 450°C, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a rate of 50-80 drops / minute; when the temperature in the co-diffusion furnace drops from 450°C to 380°C, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a rate of 40-50 drops / minute.

[0019] Preferably, the nitrogen-carbon co-infiltration treatment in step (1) includes adding a dripping agent into the co-infiltration furnace.

[0020] Preferably, the dripping agent comprises the following components by weight: 80-100 parts ethanol, 30-40 parts triethanolamine, 10-20 parts citrate, 6-10 parts rare earth oxide powder, and 1-5 parts additives; the additives are selected from one or more of dispersants, sodium gluconate, and silicates.

[0021] Preferably, before adding the seepage agent into the co-seeping furnace, the process further includes applying a seepage aid to the surface of the workpiece to be treated.

[0022] Preferably, the penetration enhancer comprises the following components by weight: 80-100 parts ethanol, 6-10 parts activated carbon powder, 10-20 parts triethanolamine, 2-5 parts rare earth oxide powder, 1-3 parts nickel powder, and 1-2 parts dispersant.

[0023] This invention provides a gaseous QPQ post-oxidation blackening agent, its preparation method, and its application. Compared with the prior art, its advantages are as follows:

[0024] The gaseous QPQ post-oxidation blackening agent of this invention uses rare earth compounds, citric acid and / or citrate, ammonium molybdate, ammonium chloride, vitamin C, formamide, manganese dioxide, phosphoric acid, calcium nitrate, ethanol, and water as raw materials. Among them, rare earth compounds can effectively increase the corrosion resistance of the workpiece, ammonium molybdate, as a colorant, can make the surface of the workpiece black, ammonium chloride can increase the depth of the penetration layer and improve the adhesion, and vitamin C can convert the rust on the surface of the workpiece into black to form a multi-element protective film. The various components work together to enable the QPQ process to fully meet the requirements of metal products for corrosion resistance and color.

[0025] Furthermore, the workpiece treated with the gas QPQ oxidation blackening agent of this invention can effectively shorten the coupling time in the coupling box, thereby greatly shortening the subsequent cleaning time and improving production efficiency. Moreover, after high-pressure cleaning at the end of coupling, the workpiece surface remains uniformly black and will not expose the substrate surface, effectively improving the adhesion of the color. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a comparison image of the workpieces after cleaning in Example 1 (left) and Comparative Example 1 (right) of the present invention. Detailed Implementation

[0028] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0029] In one aspect of the present invention, a gaseous QPQ post-oxidation blackening agent is provided, comprising, by weight, the following components: 15-30 parts of rare earth compound, 10-15 parts of citric acid and / or citrate, 5-15 parts of ammonium molybdate, 3-8 parts of ammonium chloride, 15-25 parts of vitamin C, 10-30 parts of formamide, 5-10 parts of manganese dioxide, 5-10 parts of phosphoric acid, 15-30 parts of calcium nitrate, 30-40 parts of ethanol, and 5000 parts of water.

[0030] Rare earth elements have larger molecular diameters than cast iron workpieces. In particular, rare earth molecules, after high-temperature decomposition, can compensate for the low density of cast iron workpieces. Specifically, adding appropriate amounts of rare earth compounds can strengthen the oxide layer and increase the workpiece's corrosion resistance. Ammonium molybdate can act as a coloring agent, giving the workpiece a black surface; ammonium chloride can increase the depth of the diffusion layer, but excessive ammonium chloride can damage the oxide layer; vitamin C can transform the red and yellow rust on the workpiece surface into black, forming a multi-element protective film.

[0031] In some embodiments of the present invention, the rare earth compound is a rare earth chloride and / or a rare earth oxide, such as lanthanum chloride, cerium chloride, lanthanum oxide, cerium oxide, etc.

[0032] In some embodiments of the present invention, the citrate includes one or more of sodium citrate and potassium citrate, and citric acid and / or citrate can catalyze the decomposition of rare earth elements.

[0033] In another aspect of the present invention, the present invention provides a method for preparing the gaseous QPQ post-oxidation blackening agent according to any one of the above claims, comprising the following steps: mixing rare earth compounds, citric acid and / or citrate, ammonium molybdate, ammonium chloride, vitamin C, formamide, manganese dioxide, phosphoric acid, calcium nitrate, ethanol and water to obtain the gaseous QPQ post-oxidation blackening agent.

[0034] In some embodiments of the present invention, after mixing the above raw materials, the process further includes: thoroughly stirring and allowing the mixture to stand for a period of time, for example, 24 hours, followed by filtration to obtain gaseous QPQ post-oxidation blackening agent. The filtration can be performed through a sieve of 200 mesh or higher to remove impurities. The mesh size of the sieve is not specifically limited and can be adjusted according to actual conditions.

[0035] In another aspect, the present invention also provides the application of the gaseous QPQ post-oxidation blackening agent described in any one of the above claims or the gaseous QPQ post-oxidation blackening agent prepared by the above method in gaseous nitrogen, carbon and oxygen composite treatment.

[0036] In some embodiments of the present invention, the application of the gas QPQ post-oxidation blackening agent in the gas nitrogen-carbon-oxygen composite treatment includes the following steps:

[0037] (1) Place the workpiece to be treated in a co-diffusion furnace and perform nitriding and carbonization treatment to obtain a nitrided workpiece;

[0038] (2) The gas QPQ post-oxidation blackening agent is added into the co-diffusion furnace for drip diffusion treatment to obtain the treated workpiece.

[0039] In this invention, the workpiece to be treated is first placed in a co-diffusion furnace for nitriding and carbonization treatment to obtain a nitrided workpiece.

[0040] In some embodiments of the present invention, the co-infiltration furnace is the gas nitrogen-carbon-oxygen QPQ co-infiltration furnace for cast iron products disclosed in the patent application number 202020931189.7, and its structure will not be described in detail here.

[0041] In some embodiments of the present invention, the nitrocarbon co-diffusion treatment includes adding a dripping agent into the co-diffusion furnace.

[0042] The dripping agent comprises, by weight, the following components: 80-100 parts ethanol, 30-40 parts triethanolamine, 10-20 parts citrate, 6-10 parts rare earth oxide powder, and 1-5 parts additives, wherein the additives are selected from one or more of dispersants, sodium gluconate, and silicates. Specifically, the dripping agent used in this invention is the gas QPQ multi-component composite dripping agent for cast iron products disclosed in patent application number 202010466263.7.

[0043] In some embodiments of the present invention, the nitrocarburizing treatment further includes: applying a penetration aid to the surface of the workpiece to be treated. Specifically, after applying the penetration aid to the surface of the workpiece to be treated, the workpiece coated with the penetration aid is placed in a nitrocarburizing furnace, and a dripping agent is added to the nitrocarburizing furnace for nitrocarburizing treatment.

[0044] The penetration aid comprises, by weight, the following components: 80-100 parts ethanol, 6-10 parts activated carbon powder, 10-20 parts triethanolamine, 2-5 parts rare earth oxide powder, 1-3 parts nickel powder, and 1-2 parts dispersant. Specifically, the penetration aid used in this invention is the gaseous nitrogen-carbon-oxygen QPQ multi-component composite penetration aid for cast iron products disclosed in patent application number 202010466704.3.

[0045] In some embodiments of the present invention, the process of nitrogen-carbonodizing treatment using a penetration enhancer and a dripping agent is the same as the dripping process of a multi-component composite dripping agent for cast iron products disclosed in patent application number 202010466704.3, and will not be repeated here. Specifically, in a specific embodiment of the present invention, the process of nitrogen-carbonodizing treatment using a penetration enhancer and a dripping agent is the same as in Example 1 of application number 202010466704.3.

[0046] In this invention, the gaseous QPQ post-oxidation blackening agent is added to a co-diffusion furnace for drip-diffusion treatment to obtain the treated workpiece. Specifically, the gaseous QPQ post-oxidation blackening agent is added to a co-diffusion furnace for high-temperature decomposition, and then allowed to stand to allow the decomposed gaseous QPQ post-oxidation blackening agent to penetrate into the surface layer of the nitrided workpiece, thus obtaining the treated workpiece.

[0047] In some embodiments of the present invention, the dripping treatment specifically includes the following steps:

[0048] A. After lowering the temperature inside the co-infiltration furnace to 560℃, maintain the temperature for 60-90 minutes. During the constant temperature maintenance, add gaseous QPQ followed by oxidation blackening agent into the co-infiltration furnace at a rate of 150-180 drops / minute. The maintenance time can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, etc., and the dripping rate can be 150 drops / minute, 160 drops / minute, 170 drops / minute, 180 drops / minute, etc.

[0049] B. Continue to cool the temperature inside the co-diffusion furnace from 560℃ to 380℃. During the cooling process, add gaseous QPQ post-oxidation blackening agent into the co-diffusion furnace at a rate of 40-80 drops / minute.

[0050] Specifically, in step A, the temperature inside the co-infiltration furnace can be 560℃ with air cooling. After the constant temperature holding time reaches 60-90 minutes, the heating is turned off, and the furnace temperature is lowered to 380℃ before the addition of gaseous QPQ and subsequent oxidation blackening agent is stopped.

[0051] In some embodiments of the present invention, during the cooling process in step B, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a decreasing rate, specifically as follows: when the temperature in the co-diffusion furnace drops from 560°C to 450°C, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a rate of 50-80 drops / minute; when the temperature in the co-diffusion furnace drops from 450°C to 380°C, the gaseous QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a rate of 40-50 drops / minute.

[0052] During the process of reducing the temperature in the co-infiltration furnace from 560℃ to 450℃, gaseous QPQ oxidizing and blackening agent can be added to the co-infiltration furnace at a rate of 50 drops / minute, 60 drops / minute, 65 drops / minute, 70 drops / minute, 75 drops / minute, and 80 drops / minute. As the temperature continues to decrease to 380℃, the amount added is reduced. For example, gaseous QPQ oxidizing and blackening agent can be added to the co-infiltration furnace at a rate of 40 drops / minute, 45 drops / minute, and 50 drops / minute.

[0053] In some embodiments of the present invention, the settling time is 10-20 minutes, for example, 10 minutes, 12 minutes, 14 minutes, 15 minutes, 18 minutes, 20 minutes, etc. During this settling time, the nitrided workpiece can fully absorb the QPQ gas that has already decomposed at high temperature and then oxidize and blacken.

[0054] The gaseous QPQ post-oxidation blackening agent of this invention has the same components as the dripping agent and the penetration aid. When the workpiece is treated in the co-diffusion furnace, there will be no mutual repulsion, thereby enhancing the adhesion of the gaseous QPQ post-oxidation blackening agent to the workpiece surface and giving the workpiece good rust prevention and corrosion resistance. In addition, the process of attaching the gaseous QPQ post-oxidation blackening agent to the workpiece surface of this invention is carried out after the normal nitriding treatment in the early stage, mainly using the residual heat of the co-diffusion furnace, without generating excessive energy consumption.

[0055] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0056] Example 1

[0057] This embodiment provides a gaseous QPQ post-oxidation blackening agent, which has the following specific components by weight: 15 parts rare earth lanthanum chloride, 10 parts sodium citrate, 5 parts ammonium molybdate, 3 parts ammonium chloride, 12 parts formamide, 15 parts vitamin C, 5 parts manganese dioxide, 5 parts phosphoric acid, 15 parts calcium nitrate, 30 parts ethanol, and 5000 parts deionized water.

[0058] The preparation method of the gas QPQ post-oxidation blackening agent is as follows: Mix the above raw materials and stir thoroughly, let stand for 24 hours, and filter with a 200-mesh sieve to obtain the product.

[0059] The application of this gas QPQ post-oxidation blackening agent in gas nitrogen, carbon, and oxygen composite treatment follows these steps:

[0060] (1) After cleaning the surface of the workpiece to be treated, the suspension of the infiltration aid is evenly applied to the surface of the workpiece, and then placed in the co-infiltration furnace and heated at a temperature of 600±20℃.

[0061] (2) The dripping agent is added to the co-diffusion furnace at a rate of 7 mL / s to form steam. The workpiece is nitrided by the steam for 2.5 h to obtain the nitrided workpiece.

[0062] (3) Cool the co-diffusion furnace to 560℃ by air cooling and keep it at a constant temperature for 90 minutes. During the constant temperature holding process, add gaseous QPQ post-oxidation blackening agent into the co-diffusion furnace at a rate of 150 drops / minute. Then turn off the heating and cool it down by air cooling. During the cooling process, add gaseous QPQ post-oxidation blackening agent into the co-diffusion furnace at a rate of 70 drops / minute. Stop adding gaseous QPQ post-oxidation blackening agent when the temperature drops to 380℃. Let it stand for 10 minutes to allow the nitrided workpiece to fully absorb the gaseous QPQ post-oxidation blackening agent that has been decomposed at high temperature. Open the lid and take it out of the furnace to obtain the treated workpiece. The surface of the treated workpiece is uniformly light black.

[0063] (4) Place the treated workpiece into a coupling box containing grease for coupling treatment (the coupling box is used to remove the residues produced by solvent decomposition during multi-component co-diffusion and to rapidly cool the workpiece), and then clean it. The surface of the workpiece is still uniformly light black.

[0064] Example 2

[0065] This embodiment is basically the same as Embodiment 1, except that the composition of the blackening agent after gas QPQ oxidation is different.

[0066] The specific components of the gas QPQ post-oxidation blackening agent are as follows, by weight: 20 parts rare earth lanthanum chloride, 15 parts sodium citrate, 5 parts ammonium molybdate, 3 parts ammonium chloride, 20 parts formamide, 15 parts vitamin C, 5 parts manganese dioxide, 5 parts phosphoric acid, 25 parts calcium nitrate, 30 parts ethanol, and 5000 parts deionized water.

[0067] Example 3

[0068] This embodiment is basically the same as Embodiment 1, except that the composition of the blackening agent after gas QPQ oxidation is different.

[0069] The specific components of the gas QPQ post-oxidation blackening agent are as follows, by weight: 25 parts rare earth lanthanum chloride, 15 parts sodium citrate, 5 parts ammonium molybdate, 3 parts ammonium chloride, 30 parts formamide, 15 parts vitamin C, 5 parts manganese dioxide, 10 parts phosphoric acid, 30 parts calcium nitrate, 40 parts ethanol, and 5000 parts deionized water.

[0070] Example 4

[0071] This embodiment is basically the same as embodiment 3, except that step (3) is different.

[0072] (3) Cool the co-diffusion furnace to 560℃ using air cooling and maintain the temperature for 90 minutes. During the constant temperature maintenance, add gaseous QPQ post-oxidation blackening agent to the co-diffusion furnace at a rate of 150 drops / minute. Then turn off the heating and cool the furnace using air cooling. During the temperature drop from 560℃ to 450℃, add gaseous QPQ post-oxidation blackening agent to the co-diffusion furnace at a rate of 70 drops / minute. As the furnace temperature continues to decrease from 450℃ to 380℃, reduce the amount of gaseous QPQ post-oxidation blackening agent added to 45 drops / minute. Stop adding gaseous QPQ post-oxidation blackening agent when the temperature drops to 380℃. Let the furnace stand for 10 minutes to allow the nitrided workpiece to fully absorb the gaseous QPQ post-oxidation blackening agent that has been decomposed at high temperature. Open the furnace lid and remove the workpiece to obtain the treated workpiece. The surface of the treated workpiece is uniformly dark black.

[0073] Comparative Example 1

[0074] (1) After cleaning the surface of the workpiece to be treated, the suspension of the infiltration aid is evenly applied to the surface of the workpiece, and then placed in the co-infiltration furnace and heated at a temperature of 600±20℃.

[0075] (2) The dripping agent is added to the co-diffusion furnace at a rate of 7 mL / s to form steam. The workpiece is nitrided by the steam for 2.5 h to obtain the nitrided workpiece.

[0076] (3) Place the nitrided workpiece into a coupling box containing grease for coupling treatment, and then clean it to expose the gray and gray-blue matrix on the surface of the workpiece.

[0077] The coupling time, color of the workpieces after cleaning, and corrosion resistance of the workpieces in Examples 1-4 and Comparative Example 1 were tested, and the results are shown in Table 1. The corrosion resistance tests included copper sulfate titration and neutral salt spray tests.

[0078] Table 1

[0079]

[0080]

[0081] As can be seen from Table 1, by using gaseous QPQ post-oxidation blackening agent, the color of the treated workpiece can still maintain a uniform black after cleaning, effectively improving the color adhesion. Furthermore, the workpiece can withstand higher concentrations of copper sulfate titration tests, and the salt spray resistance time is significantly increased. The treated workpiece has good corrosion resistance and can meet the requirements of the workpiece for corrosion resistance and color.

[0082] By treating the workpieces with the gas QPQ post-oxidation blackening agent, the coupling time after the workpieces exit the furnace is effectively shortened from 30 minutes to 5-8 minutes, significantly improving workpiece processing efficiency. Furthermore, due to the reduced coupling time, the amount of grease adhering to the workpiece surface is greatly reduced, significantly shortening the subsequent cleaning time and further improving production efficiency. It should also be noted that when using Comparative Example 1 to treat the workpieces, 50-70 kg of cooling grease needs to be added to the coupling box daily. However, after using the gas QPQ post-oxidation blackening agent of this invention, only 25-50 kg of cooling grease needs to be added to the coupling box weekly to meet the coupling requirements, effectively reducing costs.

[0083] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. The application of a gaseous QPQ post-oxidation blackening agent in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, Includes the following steps: (1) Place the workpiece to be treated in a co-diffusion furnace and perform nitriding and carbonization treatment to obtain a nitrided workpiece; (2) Add the gas QPQ after oxidation blackening agent into the co-diffusion furnace for drip diffusion treatment to obtain the treated workpiece; The gaseous QPQ post-oxidation blackening agent, by weight, comprises the following components: 15-30 parts of rare earth compounds, 10-15 parts of citric acid and / or citrate, 5-15 parts of ammonium molybdate, 3-8 parts of ammonium chloride, 15-25 parts of vitamin C, 10-30 parts of formamide, 5-10 parts of manganese dioxide, 5-10 parts of phosphoric acid, 15-30 parts of calcium nitrate, 30-40 parts of ethanol, and 5000 parts of water.

2. The application of the gaseous QPQ post-oxidation blackening agent according to claim 1 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, The rare earth compounds are rare earth chlorides and / or rare earth oxides.

3. The application of the gaseous QPQ post-oxidation blackening agent according to claim 1 or 2 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, The citrate includes one or more of sodium citrate and potassium citrate.

4. The application of the gaseous QPQ post-oxidation blackening agent according to claim 1 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, The preparation method of the gas QPQ post-oxidation blackening agent includes the following steps: Rare earth compounds, citric acid and / or citrate, ammonium molybdate, ammonium chloride, vitamin C, formamide, manganese dioxide, phosphoric acid, calcium nitrate, ethanol, and water are mixed to obtain gaseous QPQ post-oxidation blackening agent.

5. The application of the gaseous QPQ post-oxidation blackening agent according to claim 1 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, Step (2) specifically includes the following steps: A. After lowering the temperature in the co-infiltration furnace to 560℃, maintain the temperature for 60-90 minutes. During the constant temperature maintenance, add gaseous QPQ followed by oxidation blackening agent into the co-infiltration furnace at a rate of 150-180 drops / minute. B. Continue to cool the temperature inside the co-diffusion furnace from 560℃ to 380℃. During the cooling process, add gaseous QPQ post-oxidation blackening agent into the co-diffusion furnace at a rate of 40-80 drops / minute.

6. The application of the gaseous QPQ post-oxidation blackening agent according to claim 5 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, In step B, during the cooling process, the gas QPQ post-oxidation blackening agent is added to the co-diffusion furnace at a decreasing rate, as follows: During the process of the temperature inside the co-infiltration furnace decreasing from 560℃ to 450℃, gaseous QPQ followed by oxidation and blackening agent is added into the co-infiltration furnace at a rate of 50-80 drops / minute; during the process of the temperature inside the co-infiltration furnace decreasing from 450℃ to 380℃, gaseous QPQ followed by oxidation and blackening agent is added into the co-infiltration furnace at a rate of 40-50 drops / minute.

7. The application of the gaseous QPQ post-oxidation blackening agent according to claim 1, 5, or 6 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, The nitrocarbon co-diffusion treatment in step (1) includes: adding a dripping agent into the co-diffusion furnace; The dripping agent comprises the following components by weight: 80-100 parts of ethanol, 30-40 parts of triethanolamine, 10-20 parts of citrate, 6-10 parts of rare earth oxide powder, and 1-5 parts of additives. The additive is selected from one or more of dispersants, sodium gluconate, and silicates.

8. The application of the gaseous QPQ post-oxidation blackening agent according to claim 7 in gaseous nitrogen, carbon, and oxygen composite treatment, characterized in that, Before adding the dripping agent into the co-diffusion furnace, the process further includes: applying a seepage aid to the surface of the workpiece to be treated; The penetration enhancer comprises the following components by weight: 80-100 parts ethanol, 6-10 parts activated carbon powder, 10-20 parts triethanolamine, 2-5 parts rare earth oxide powder, 1-3 parts nickel powder, and 1-2 parts dispersant.

Images