Process for nitroxidizing a metal part

Abstract

The application discloses a kind of nitrogen oxide treatment processes of metal parts, it is related to metal processing technical field, comprising the following steps: S1, metal surface is cleaned and pretreated;S2, product is hung;S3, start nitrogen furnace and start heating, ammonia, methanol, three kinds of raw materials of triethanolamine are input;S4, sodium hydroxide-containing distilled water solution is input and oxidized and is treated;S5, after nitrogen oxide treatment, metal is taken out and immersed in rust-proof oil and packaged.The corrosion-resistant gas nitrogen oxide treatment process increases the wear resistance of metal parts, impact resistance, fatigue resistance, mechanical strength, greatly improves the service life of metal parts, and improves work efficiency, convenient to use.

Description

Technical Field

[0001] This invention relates to the field of metal processing technology, and more particularly to a nitrogen oxidation process for metal parts. Background Technology

[0002] For any metal part, fatigue resistance, wear resistance, high strength, and aesthetics are fundamental requirements for its surface. Especially for metal components used in harsh environments, superior resistance to corrosion from acids, alkalis, and salts is essential. Metal products require anti-corrosion processes during production. The anti-corrosion gas nitriding process involves infiltrating nitrogen and carbon into the surface of the metal part, forming a nitrogen-carbon compound layer. This is followed by high-temperature oxidation to create a black oxide film. Both the nitrogen-carbon compound layer and the oxide film possess extremely high hardness and superior corrosion resistance. Current nitriding processes typically involve adding different chemical raw materials to a nitriding furnace at a specific temperature for a certain time, followed by cooling and other post-treatment processes. The furnace temperature, the rate of raw material introduction, and the decomposition rate all affect the nitriding treatment effect. Therefore, selecting the appropriate raw materials and their proportions and rates for introduction into the furnace is crucial for improving the nitriding process and is a worthy area of ​​research. Summary of the Invention

[0003] This invention proposes a nitrogen oxidation treatment process for metal parts, using ammonia, methanol, and triethanolamine as nitriding raw materials and sodium hydroxide solution as oxidizing raw material. By controlling the proportion and rate of the raw materials introduced into the furnace, the treatment effect of the nitrogen oxidation process can be improved. The resulting nitrogen-carbon compound layer and oxide film have extremely high hardness and strong corrosion resistance, increasing the wear resistance, impact resistance, fatigue resistance, and mechanical strength of the metal parts, and significantly extending the service life of the metal parts.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A nitrogen oxidation treatment process for metal parts includes the following steps: S1. Clean and pre-treat the metal surface; S2. Hang the products neatly, hoist them into the nitriding furnace, cover the furnace and seal it; S3. Start the nitriding furnace to begin heating. Once the temperature reaches the range of 520-580℃, simultaneously introduce ammonia, methanol, and triethanolamine. Control the ammonia decomposition rate between 15-35%, the methanol rate at 50-55 ml / min, and the triethanolamine rate at 30-40 ml / min. The nitriding and carbonizing treatment time is 4-5 hours. After the nitriding and carbonizing is completed, stop introducing ammonia, methanol, and triethanolamine, and turn on the vacuum pump to remove any remaining gas from the furnace. S4. Oxidation treatment is carried out by passing a distilled aqueous solution containing 10-15% sodium hydroxide through a flow rate of 30-50 ml / min for 30-60 minutes.

[0005] S5, after the metal is oxidized by nitrogen, it is soaked in rust-preventive oil and packaged.

[0006] Specifically, S1 includes: S11: Ultrasonic degreasing: Immerse the metal product in 5% to 10% degreasing agent, and treat at a temperature of 60-80℃ for 10-20 minutes. S12: Water washing: Immerse the degreased metal products in clean water with a pH of 7-8 for 2-5 minutes; S13: Rust prevention: Immerse the washed metal products in 5% to 10% rust inhibitor at a temperature of 60-80℃ for 1-3 minutes. S14: Drying: The rust-proofed metal products are introduced into a drying device with hot air temperature of 60-80℃ and the drying time is 30-40 minutes.

[0007] Specifically, in step S5, immersion in rust-preventive oil: immersion in rust-preventive oil at room temperature for 1-3 minutes.

[0008] Specifically, the metal obtained through S3 and S4 has a metallographic structure in which the outermost layer is a black Fe3O4 oxide film, the next layer is a nitrogen and carbon compound layer, the next layer is a diffusion layer, and the innermost layer is the original structure of the metal matrix.

[0009] The beneficial effects of this invention are as follows: The nitrogen oxidation process for metal parts involves infiltrating nitrogen and carbon into the surface of the metal parts, generating a nitrogen-carbon compound layer. This is followed by high-temperature oxidation to form a black oxide film. Both the nitrogen-carbon compound layer and the oxide film possess extremely high hardness and superior corrosion resistance, increasing the wear resistance, impact resistance, fatigue resistance, and mechanical strength of the metal parts, significantly extending their service life. This invention's nitrogen oxidation process is an innovative one, using ammonia, methanol, and triethanolamine as nitriding raw materials and sodium hydroxide solution as the oxidizing raw material. By controlling the ammonia decomposition rate and the flow rates of methanol and triethanolamine within an optimal range, the nitriding effect is improved. Further oxidation with sodium hydroxide, with precise concentration and controlled flow rate, significantly enhances the surface treatment effect, greatly extending the service life of the metal parts. Metal parts treated with this nitrogen oxidation process can have a lifespan more than 10 times longer than their original state. Furthermore, this nitrogen oxidation process is environmentally friendly, generating no solid waste. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the processing flow framework of the present invention. Detailed Implementation

[0011] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example

[0012] For the nitrogen oxidation treatment process of metal parts, please refer to [link / reference]. Figure 1 It includes the following steps: Includes the following steps: S1. Clean and pre-treat the metal surface; S11: Ultrasonic degreasing: Immerse the metal product in 5% to 10% degreasing agent, and treat at a temperature of 60-80℃ for 10-20 minutes. S12: Water washing: Immerse the degreased metal products in clean water with a pH of 7-8 for 2-5 minutes; S13: Rust prevention: Immerse the washed metal products in 5% to 10% rust inhibitor at a temperature of 60-80℃ for 1-3 minutes. S14: Drying: The rust-proofed metal products are introduced into a drying device with hot air temperature of 60-80℃ and the drying time is 30-40 minutes.

[0013] S2. Hang the products neatly, hoist them into the nitriding furnace, cover the furnace and seal it; S3. Start the nitriding furnace to begin heating. Once the temperature reaches the range of 520-580℃, simultaneously introduce ammonia, methanol, and triethanolamine. Control the ammonia decomposition rate between 15-35%, the methanol rate at 50-55 ml / min, and the triethanolamine rate at 30-40 ml / min. The nitriding and carbonizing treatment time is 4-5 hours. After the nitriding and carbonizing is completed, stop introducing ammonia, methanol, and triethanolamine, and turn on the vacuum pump to remove any remaining gas from the furnace. S4. Oxidation treatment is performed by passing a distilled aqueous solution containing 10-15% sodium hydroxide through a flow rate of 30-50 ml / min for 30-60 minutes. The resulting metal has a metallographic structure in which the outermost layer is a black iron(III) oxide film (Fe3O4), the next layer is a nitrogen-carbon compound layer, the next layer is a diffusion layer, and the innermost layer is the original metal matrix structure.

[0014] S5, after the metal undergoes nitrogen oxidation treatment, it is immersed in rust-preventive oil and then packaged. Immersion in rust-preventive oil: Immerse in rust-preventive oil at room temperature for 1-3 minutes.

[0015] When metal parts are heated to a set temperature of 520-580℃ in a nitriding furnace, ammonia, methanol, triethanolamine, and other gases are introduced into the furnace to decompose nitrogen and carbon atoms. Under high temperature and pressure, the diffusion rate of carbon atoms in α-iron is slightly higher than that of nitrogen atoms. However, the solid solubility of carbon atoms in α-iron is lower than that of nitrogen atoms. Therefore, carbon quickly reaches saturation on the metal surface and precipitates ultra-microscopic carbides. The carbides further promote the absorption of nitrogen atoms. When nitrogen atoms reach saturation in α-iron and then generate ε and γ' phases, the ε and γ' phases dissolve more carbon. Under the interaction of nitrogen and carbon atoms, nitrogen and carbon atoms begin to slowly penetrate into the metal surface. After a period of time, a compound layer can be generated on the metal surface. The required thickness of the compound layer can be obtained by controlling the time.

[0016] Once the required thickness of the compound layer is formed on the metal surface, a 10% sodium hydroxide solution is introduced into the nitriding furnace. Under high temperature, the metal reacts chemically with the sodium hydroxide solution, forming a black iron(III) oxide film on the metal surface.

[0017] Quality Inspection: The quality tests of two gray cast iron samples after undergoing the nitrogen oxidation treatment process of this invention are shown in Table 1 below: Table 1 is a quality inspection table for gray cast iron samples. Samples 1 and 2 are gray cast iron samples treated with the nitrogen oxidation process of this invention, while sample 3 is a gray cast iron sample that has not undergone the nitrogen oxidation process. Table 1

[0018] As shown in the table above, after the nitrogen oxidation treatment process of the present invention, the two gray cast iron samples were observed to have a surface dense oxide film depth of about 20-25 μm and a compound layer depth of 27-38 μm. No obvious porosity, vein-like nitrides, or obvious diffusion layer were observed. The microstructure is better than that of Grade I.

[0019] Sample 3 was not subjected to nitrogen oxidation treatment, and obvious porosity was observed when the sample hardness was measured at 180 HV.

[0020] II. The corrosion resistance of two samples of gray cast iron parts after the nitrogen oxidation treatment process of this invention is shown in Table 2 below: Table 2

[0021] Test results: No rust was observed on the metal parts after 750 hours of testing.

[0022] Gray cast iron that has not undergone the nitrogen oxidation treatment process of this invention will have all its metal parts rusted after a 30-minute salt spray test as shown in Table 2.

[0023] III. The quality tests of two alloy structural steel samples after the nitrogen oxidation treatment process of this invention are shown in Table 3 below: Table 3

[0024] As shown in the table above, the compound depth is about 24-36 μm, the diffusion layer depth is about 412 μm, no abnormal vein-like nitrides were observed, which is better than grade 2. The average hardness of the nitrided layer of the sample is 1069.5-1072.7 HV, the total depth of the nitrided layer is about 438 μm, and the nitrides are better than grade 2.

[0025] IV. The corrosion resistance of alloy structural steel samples after the nitrogen oxidation treatment process of this invention is shown in Table 4 below, based on neutral salt spray tests of two samples: Table 4

[0026] Test results: No rust was observed after 700 hours of testing.

[0027] Alloy structural steel that has not undergone the nitrogen oxidation treatment process of this invention will show rust on the surface of all gray cast iron metal parts after a 30-minute salt spray test as shown in Table 4.

[0028] Based on the above experimental results, the metal parts treated by the process of this invention have the following characteristics: 1. Its metallographic structure: the outermost layer is a black iron oxide film, the next layer is a nitrogen and carbon compound layer, the next layer is a diffusion layer, and the innermost layer is the original structure of the metal matrix. 2. It has high hardness, high wear resistance, and extremely high corrosion resistance. It can withstand 700 hours of neutral salt spray test and has a rust prevention period of more than 20 years. It is widely used in metal parts for military, nuclear power, automobile, machinery, shipbuilding, aviation, wind power and other industries.

[0029] The innovative process in this invention greatly extends the service life of metal parts. Metal parts treated with gas nitrogen oxidation can have a lifespan that is more than 10 times longer than those in their original state. In terms of environmental protection, no solid waste is generated, making it environmentally friendly.

[0030] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A nitrogen oxidation treatment process for metal parts, characterized in that, Includes the following steps: S1. Clean and pre-treat the metal surface; S2. Hang the products neatly, hoist them into the nitriding furnace, cover the furnace and seal it; S3. Start the nitriding furnace to begin heating. Once the temperature reaches the range of 520-580℃, simultaneously introduce ammonia, methanol, and triethanolamine for nitrocarburizing treatment. The ammonia decomposition rate should be controlled between 15-35%; the methanol rate should be controlled at 50-55 ml / min; and the triethanolamine rate should be controlled at 30-40 ml / min. The nitrocarburizing treatment time is 4-5 hours. After the nitrocarburizing is completed, stop introducing ammonia, methanol, and triethanolamine, and turn on the vacuum pump to remove all residual gas from the furnace. S4. Oxidation treatment is carried out by passing a distilled aqueous solution containing 10-15% sodium hydroxide through a flow rate of 30-50 ml / min for 30-60 minutes. S5, after the metal is oxidized by nitrogen, it is soaked in rust-preventive oil and packaged.

2. The nitrogen oxidation treatment process for metal parts according to claim 1, characterized in that, S1 includes: S11: Ultrasonic degreasing: Immerse the metal product in 5% to 10% degreasing agent, and treat at a temperature of 60-80℃ for 10-20 minutes. S12: Water washing: Immerse the degreased metal products in clean water with a pH of 7-8 for 2-5 minutes; S13: Rust prevention: Immerse the washed metal products in 5% to 10% rust inhibitor at a temperature of 60-80℃ for 1-3 minutes. S14: Drying: The rust-proofed metal products are introduced into a drying device with hot air temperature of 60-80℃ and the drying time is 30-40 minutes.

3. The nitrogen oxidation treatment process for metal parts according to claim 1, characterized in that, In step S5, immersion in rust-preventive oil: immerse in rust-preventive oil at room temperature for 1-3 minutes.

4. The nitrogen oxidation treatment process for metal parts according to claim 1, characterized in that, The metal obtained through processes S3 and S4 has a metallographic structure in which the outermost layer is a black Fe3O4 oxide film, the next layer is a nitrogen and carbon compound layer, the next layer is a diffusion layer, and the innermost layer is the original structure of the metal matrix.

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