Method for preparing high-performance die steel through liquid phase plasma electrolysis

Abstract

The invention discloses a method for preparing high-performance die steel by liquid-phase plasma electrolysis in the technical field of electrolytic penetration, which mainly comprises the following steps: taking H13 die steel as a negative electrode and graphite as a positive electrode, respectively connecting the H13 die steel and the graphite with leads, putting the H13 die steel and the graphite into electrolyte, and introducing direct current for electrolysis, so that liquid-phase plasma containing carbon and nitrogen is generated in the electrolyte; and moving towards a negative electrode where the H13 die steel is located, and treating for a specific time to form a wear-resistant composite layer containing carbon and nitrogen on the surface of the H13 die steel. According to the method, the H13 die steel is used as the negative electrode, the graphite is used as the positive electrode, the H13 die steel and the graphite are put into the specific electrolyte, the direct current with the specific voltage is introduced for electrolysis, carbon-nitrogen-containing plasmas generated in the electrolyte can permeate into the surface of the H13 die steel within several minutes, a compact wear-resistant layer is formed, the wear resistance of the H13 die steel material is greatly improved, and the service life of the H13 die steel material is prolonged. And the whole process is high in speed, high-temperature and low-vacuum conditions are not needed, workpiece deformation cannot be caused, and the permeation efficiency and the permeation quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic infiltration, and in particular to a method for preparing high-performance die steel by utilizing liquid phase plasma electrolysis. Background Art

[0002] In the preparation process of metal materials, in order to improve the hardness, wear resistance and corrosion resistance of metal materials, it is usually necessary to perform surface modification treatment on them. The most commonly used method at present is thermal diffusion technology, the basic principle of which is to diffuse the elements to be diffused (such as carbon and nitrogen) into the surface of the metal material or workpiece by heating, thereby forming a surface alloy layer. This technology can be divided into many types, including solid thermal diffusion, liquid thermal diffusion, gas phase thermal diffusion, plasma thermal diffusion and laser assisted thermal diffusion. Among them, gas plasma infiltration technology is more widely used, and its disadvantages are high processing temperature, long processing time, easy deformation of the workpiece, and the reaction needs to be carried out under low vacuum conditions. Summary of the invention

[0003] In order to overcome the above-mentioned deficiencies of the existing gaseous plasma infiltration technology, the technical problem to be solved by the present invention is to provide a method for preparing high-performance mold steel by liquid phase plasma electrolysis with low energy consumption and short time.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A method for preparing high-performance mold steel by using liquid plasma electrolysis, wherein H13 mold steel is used as the negative electrode and graphite is used as the positive electrode. The two are connected with wires and placed in an electrolyte, and direct current is passed for electrolysis, so that liquid plasma containing carbon and nitrogen is generated in the electrolyte and moves toward the negative electrode where the H13 mold steel is located. After a specific treatment time, a wear-resistant composite layer containing carbon and nitrogen is formed on the surface of the H13 mold steel. Then, the H13 mold steel is heated and insulated to form an oxide film on its surface.

[0006] Furthermore, the electrolyte includes water, urea, potassium chloride, formamide and cerium oxide.

[0007] Furthermore, the electrolyte has a ratio of 0.25 g urea, 10 g potassium chloride, 0.25 ml formamide and 0.2% by weight cerium oxide per 100 ml water.

[0008] Furthermore, the voltage of the DC power supplied is 150-200V.

[0009] Furthermore, the voltage of the DC power supplied is 150V, 175V or 200V.

[0010] Furthermore, the processing time is 3-7 minutes.

[0011] Furthermore, the processing time is 3 min, 5 min or 7 min.

[0012] Furthermore, when the H13 die steel is heated and kept warm, the warming temperature is 550° C. and the warming time is 4 hours.

[0013] The beneficial effects of the present invention are as follows: using H13 mold steel as the negative electrode and graphite as the positive electrode, putting them into a specific electrolyte, and passing direct current of a specific voltage for electrolysis, the carbon-nitrogen plasma generated in the electrolyte can penetrate into the surface of the H13 mold steel within a few minutes to form a dense wear-resistant layer, which greatly improves the wear resistance of the H13 mold steel material, and the whole process is fast, does not require high temperature and low vacuum conditions, will not cause deformation of the workpiece, and improves the penetration efficiency and penetration quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is the XRD phase analysis result diagram of H13 die steel under different voltages of the present invention;

[0015] Figure 2 This is a graph showing weight analysis results of samples at different holding times of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings.

[0017] The present invention provides a method for preparing high-performance mold steel by utilizing liquid-phase plasma electrolysis, comprising the following steps: using H13 mold steel as a negative electrode and graphite as a positive electrode, connecting the two with wires respectively and placing them in an electrolyte, then introducing direct current for electrolysis, so that liquid-phase plasma containing carbon and nitrogen is generated in the electrolyte, and after electrolysis for a specific time, a wear-resistant composite layer containing carbon and nitrogen is formed on the surface of the H13 mold steel, and then the H13 mold steel is heated and insulated to form an oxide film on its surface.

[0018] Wherein, the electrolyte includes water, urea, potassium chloride, formamide and cerium oxide. The preferred ratio of the electrolyte is that every 100 ml of water corresponds to 0.25 g of urea, 10 g of potassium chloride, 0.25 ml of formamide and 0.2% by weight of cerium oxide. The voltage of the DC power supplied is 150-200 V, preferably 150 V, 175 V or 200 V. The time of the electrolytic treatment is 3-7 min, preferably 3 min, 5 min or 7 min. Heating and heat-insulating the H13 mold steel after plasma penetration can cause the oxygen in the air to react with the Fe ions in the wear-resistant composite layer to form an oxide film, which is mixed with the Fe carbides and nitrides produced by the previous plasma impact, further improving the wear resistance and oxidation resistance of the wear-resistant composite layer.

[0019] The present invention is further described below by way of examples.

[0020] Example 1

[0021] The same H13 mold steel was used for penetration treatment according to the voltage and treatment time shown in Table 1, wherein the electrolyte was prepared according to the ratio of 0.25g urea, 10g potassium chloride, 0.25ml formamide and 0.2% cerium oxide by weight per 100ml water. The Vickers hardness data of five points on the surface of the treated material were randomly measured for comparison, and the obtained data are shown in Table 1.

[0022] Table 1 Experimental data of Vickers hardness (HV) of high performance die steel prepared by liquid plasma electrolysis

[0023]

[0024]

[0025] It can be seen from the data in Table 1 that the Vickers hardness (HV) value has an upward trend as the voltage increases, whether the plasma electrolysis is 3 minutes, 5 minutes or 7 minutes. Especially under the conditions of 3 minutes and 175V, the upward trend of Vickers hardness (HV) is basically linear, and the highest Vickers hardness (HV) value is 1318, which is the highest value of Vickers hardness (HV) measured, 215 higher than the highest value of 1103 of the raw material. Whether at a voltage of 150 volts, 175 volts or 200 volts, the surface hardness of H13 mold steel 4 has an upward trend as the processing time increases, proving that the hardness increases with the increase in processing time. It can be reflected that different times and voltages have an impact on Vickers hardness (HV), and the higher the Vickers hardness (HV), the better its wear resistance. In addition, an 80% duty cycle was used during this experiment.

[0026] Depend on Figure 1 It can be seen from the XRD phase analysis results of H13 die steel 4 corresponding to different treatment voltages when the treatment time is 5min that after carbonitriding treatment, Fe carbides and nitrides are produced on the surface of H13 die steel, and the carburized layer is mainly composed of Fe, Fe 19 Ni, Co3Fe7, Fe3C, Fe 2-3N, etc. During the carbonitriding process, the interface reaction is accelerated and the diffusion of active atoms in the H13 mold steel is promoted by the collision of active carbon and nitrogen atoms in the plasma zone. After that, the surface temperature of the H13 mold steel will rise, accelerating the interface reaction and promoting the diffusion of active atoms in the H13 mold steel. The carbon atoms and nitrogen atoms that penetrate into the H13 mold steel first form an interstitial solid solution. When they reach a supersaturated solid solubility, iron nitrogen and carbon compounds will be generated on the surface of the H13 mold steel. Compared with the untreated H13 mold steel 4, the treated H13 mold steel has significantly increased the Fe-N and Fe-C phases on the surface of the H13 mold steel 4 in the co-diffusion layer.

[0027] In addition, if Figure 2 As shown in the figure, the specimens were electrolytically infiltrated at 200 volts, and the H13 mold steel treated for different times was electrolytically infiltrated at 550 volts. 0 After 4 hours of heat preservation, the weight increase of the sample after cooling in the furnace. The analysis shows that with the increase of treatment time, the weight increase of the sample shows a downward trend, proving that the thickness of the oxide film increases with time. The formed oxide film protects the H13 mold steel and increases the high temperature oxidation resistance of the H13 mold steel.

Claims

1. A method for preparing high-performance mold steel by liquid plasma electrolysis, characterized in that: Take H13 mold steel as the negative electrode and graphite as the positive electrode. Connect the two with wires and put them into electrolyte. Apply direct current for electrolysis to generate liquid plasma containing carbon and nitrogen in the electrolyte and move to the negative electrode where the H13 mold steel is located. After a specific treatment time, a wear-resistant composite layer containing carbon and nitrogen is formed on the surface of the H13 mold steel. Then, the H13 mold steel is heated and kept warm to form an oxide film on its surface.

2. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 1, characterized in that: The electrolyte includes water, urea, potassium chloride, formamide and cerium oxide.

3. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 2, characterized in that: The electrolyte has a ratio of 0.25 g urea, 10 g potassium chloride, 0.25 ml formamide and 0.2% by weight cerium oxide per 100 ml water.

4. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 1, characterized in that: The voltage of the DC power input is 150~200V.

5. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 4, characterized in that: The voltage of the DC power input is 150V, 175V or 200V.

6. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 1, characterized in that: The processing time is 3-7 minutes.

7. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 6, characterized in that: The processing time is 3min, 5min or 7min.

8. The method for preparing high-performance mold steel by liquid phase plasma electrolysis according to claim 1, characterized in that: When the H13 mold steel is heated and kept warm, the holding temperature is 550°C and the holding time is 4 hours.

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