A BH catalyst and its preparation method and a carburizing heat treatment method for gear steel

Abstract

The present invention discloses a BH accelerating agent, a preparation method thereof, and a carburizing heat treatment method for gear steel. The BH accelerating agent comprises four components. Component A includes lanthanum oxide, iron chloride, sodium oxide, and potassium oxide. Component B includes trinitrotoluene and argon microspheres. Component C includes sucrose and sodium carbonate. Component D includes a surfactant and a dispersant. Using the BH accelerating agent provided by the present invention in the carburizing heat treatment of gear steel can achieve a low-temperature, fast, and efficient carburizing process, significantly improve the carburizing efficiency and the quality of the carburized layer, reduce the deformation of the workpiece, optimize the microstructure, and improve the overall performance of the part. The average friction coefficient of the carburized gear steel prepared by the present invention is 0.32 - 0.35, and the wear volume is 0.72 - 0.77 mm<supgt;3< / supgt;. Compared with the existing BH accelerating agent, the wear resistance of the carburized gear steel is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of BH catalysts, and in particular to a BH catalyst and a preparation method thereof, and a carburizing heat treatment method for gear steel. Background Art

[0002] Carburizing is a typical chemical gas-solid phase reaction, which is widely used in the heat treatment process of parts such as gears and bearings. Through carburizing treatment, the hardness, wear resistance and fatigue strength of these parts can be significantly improved, thereby extending their service life. However, the traditional carburizing process faces a series of challenges in practical applications. First, the slow carburizing speed is one of the key factors restricting the efficiency of the traditional process, which not only increases the production cycle, but also may lead to an increase in production costs. Secondly, the traditional carburizing process usually requires a higher process temperature, which not only consumes a lot of energy, but may also cause quality problems such as workpiece deformation and cracking, further affecting the performance and reliability of the product.

[0003] In order to solve these problems, scholars and enterprises at home and abroad have been actively exploring new catalysts and technologies. Among them, BH catalyst technology has gradually become a research hotspot in the field of heat treatment with its significant advantages such as high efficiency, energy saving and environmental protection. BH catalyst accelerates the diffusion rate of carbon atoms by reducing the activation energy of carburizing reaction, thereby significantly improving carburizing efficiency. At the same time, BH catalyst technology can also reduce process temperature to a certain extent, reduce workpiece deformation and improve product quality. Despite this, there are still some shortcomings and areas for improvement in existing BH catalysts and technologies. In some cases, existing BH catalysts still have problems such as insufficient carburizing speed, insufficient uniformity of carburized layer, and limited adaptability to workpiece materials. In addition, in practical applications, existing carburizing heat treatment processes often require complex equipment and operating procedures, which increases production costs and operational difficulties.

[0004] Therefore, the development of new and efficient BH catalysts and their carburizing heat treatment processes to further improve carburizing efficiency and quality and reduce production costs and environmental impact has become an urgent issue to be solved in the field of heat treatment technology. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a BH catalyst and a preparation method thereof and a carburizing heat treatment method for gear steel. The BH catalyst has the characteristics of high efficiency, energy saving, and environmental protection, and can significantly increase the carburizing rate, reduce the process temperature, reduce workpiece deformation, optimize the organization, and improve the wear resistance and service life of the gear steel.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] A BH penetration catalyst, comprising the following components in percentage by mass: component A 52.0-57.0%, component B 21.0-26.0%, component C 20.0-21.0%, component D 1.0-2.0%; wherein,

[0008] Component A includes the following components in percentage by mass: lanthanum oxide (La2O3) 15.0-25.0%, ferric chloride (FeCl3) 25.0-30.0%, sodium oxide (Na2O) 30.0-33.0%, potassium oxide (K2O) 20.0-22.0%;

[0009] Component B includes the following components in percentage by mass: 18.0-23.0% trinitrotoluene (TNT), 77.0-82.0% argon microspheres (Ar);

[0010] Component C includes the following components in percentage by weight: sucrose (C 12 H 22 O 11 ) 56.0-63.0%, sodium carbonate (Na2CO3) 37.0-44.0%;

[0011] Component D includes the following components in percentage by mass: 67.0-74.0% of surfactant and 26.0-33.0% of dispersant.

[0012] Among them, component A is a high-efficiency composite decomposition catalyst, component B is a substance that intermittently generates shock waves, and component C is a chemical substance that changes the decomposition process of the penetrant.

[0013] Furthermore, the argon microspheres are prepared by encapsulating argon in a silicon dioxide (SiO2) shell.

[0014] Furthermore, the thickness of the silicon dioxide shell is 0.12-0.15 mm.

[0015] Furthermore, the particle size of the argon microspheres is 0.8-1.2 mm.

[0016] Furthermore, the surfactant is sodium dodecylbenzene sulfonate (SDBS), and the dispersant is polymethylpyrrolidone (PVP).

[0017] A method for preparing the above-mentioned BH penetration catalyst comprises the following steps:

[0018] (1) mixing lanthanum oxide, ferric chloride, sodium oxide and potassium oxide in proportion to obtain component A;

[0019] (2) mixing trinitrotoluene and argon microspheres according to a certain proportion to obtain component B;

[0020] (3) mixing sucrose and sodium carbonate according to a certain proportion to obtain component C;

[0021] (4) mixing the surfactant and the dispersant in proportion to obtain component D;

[0022] (5) Component A, component B, component C and component D are mixed according to a certain proportion to obtain the BH permeation catalyst.

[0023] In a specific embodiment, the preparation method comprises the following steps:

[0024] (1) mixing lanthanum oxide, ferric chloride, sodium oxide and potassium oxide in weight percentages of 15.0-25.0%, 25.0-30.0%, 30.0-33.0% and 20.0-22.0%, and grinding into uniform fine powder to obtain component A;

[0025] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0-23.0% and 77.0-82.0% to obtain component B;

[0026] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0-63.0% and 37.0-44.0% to obtain component C, and dissolving component C in a solvent to obtain a component C solution;

[0027] (4) mixing a surfactant and a dispersant in an amount of 67.0-74.0% by mass and 26.0-33.0% by mass to obtain a component D, and dissolving the component D in a solvent to obtain a component D solution;

[0028] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in component A, component B, component C solution and component D in component D solution is (52-57):(21-26):(20-21):(1-2), to obtain the BH permeation catalyst.

[0029] Furthermore, the solvent is methanol, and the BH catalyst reaches a saturated state in the solvent.

[0030] The present invention also protects the use of the above-mentioned BH catalyst in the carburizing heat treatment of gear steel.

[0031] A method for carburizing heat treatment of gear steel, using the above-mentioned BH catalyst for carburizing treatment, comprises the following steps:

[0032] S1. Carburize the gear steel at 735-745 °C during the isothermal period, with a carburizing atmosphere flow rate of 1.5-2.0 L / min and a carbon potential of 0.9-1.0 wt%;

[0033] S2. The gear steel obtained in S1 was subjected to a strong carburizing treatment at 805-825 °C, the carburizing atmosphere flow rate was 3.0-4.0 L / min, the amount of BH catalyst was 1.8-3.2% of the total mass of the carburizing atmosphere, and the carbon potential was 1.3-1.4 wt%;

[0034] S3. The gear steel obtained in S2 was subjected to transitional carburizing treatment at 805-825 °C, the carburizing atmosphere flow rate was 2.4-2.8 L / min, the amount of BH catalyst was 1.8-3.2% of the total mass of the carburizing atmosphere, and the carbon potential was 1.2-1.3 wt%;

[0035] S4. The gear steel obtained in S3 is subjected to diffusion period carburizing treatment at 805-825 ℃, the carburizing atmosphere flow rate is 1.7-2.2 L / min, the amount of BH catalyst is 1.8-3.2% of the total mass of the carburizing atmosphere, the carbon potential is 1.0-1.1 wt%, and the diffusion period carburizing treatment is followed by air cooling to 20-30 ℃;

[0036] S5. The gear steel obtained in S4 is subjected to high temperature tempering treatment at 620-625°C;

[0037] S6. The gear steel obtained in S5 is quenched at 805-825°C;

[0038] S7. The gear steel obtained in S6 is subjected to deep cryogenic treatment at -75°C to -90°C, and then subjected to low temperature tempering treatment at 180-195°C to obtain carburized gear steel.

[0039] Furthermore, in S1-S4, the carburizing atmosphere is composed of methanol, acetone and kerosene, and the volume ratio of methanol, acetone and kerosene is 1:(1.5-2.5):(2.5-3.5).

[0040] Furthermore, in S1, the time of the carburizing treatment during the isothermal period is 0.3-0.5 h.

[0041] Furthermore, in S2, the time of the carburizing treatment in the strong carburizing period is 1.0-1.7 h; in S3, the time of the carburizing treatment in the transition period is 0.3-0.5 h; in S4, the time of the carburizing treatment in the diffusion period is 1.0-1.5 h.

[0042] Furthermore, in S5, 1-2 high temperature tempering treatments are performed, and the duration of each high temperature tempering treatment is 2-3 h.

[0043] Furthermore, in S6, the quenching treatment time is 50-55 min.

[0044] Furthermore, in S6, the quenching treatment is performed by oil quenching.

[0045] Furthermore, in S7, the time of the deep cryogenic treatment is 0.6-0.9 h, and the time of the low temperature tempering treatment is 2-2.8 h.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The BH catalyst provided by the present invention adopts a more sophisticated composite catalyst system. By precisely controlling the ratio of rare earth elements, transition metals and two alkaline oxides, the catalyst can be fully decomposed at a lower temperature, thereby increasing the activity and number of carbon atoms, achieving a significant improvement in catalytic activity and significantly shortening the heat treatment cycle.

[0048] (2) The BH catalyst provided by the present invention introduces a controllable release shock wave material, which is combined with the inert gas microspheres encapsulated in the silica shell, and can produce a more uniform and strong shock wave effect during the carburizing process, effectively destroying the gas film layer on the surface of the workpiece, promoting full contact between the carburizing medium and the workpiece surface, and improving the uniformity and depth consistency of carburizing. In addition, surfactants and dispersants with hydrophilic, lipophilic, surface tension adjustment between different phases, compatibility promotion, dispersion and other functions are introduced, which can form steric hindrance or electrostatic repulsion in the medium, thereby preventing particle agglomeration.

[0049] (3) The present invention uses BH catalyst to perform carburizing heat treatment on gear steel, which can achieve low-temperature, rapid and efficient carburizing process, significantly improve carburizing efficiency and carburized layer quality, reduce workpiece deformation, optimize structure, and improve the overall performance of parts. The average friction coefficient of the carburized gear steel prepared by the present invention is 0.32-0.35, and the wear volume is 0.72-0.77 mm 3 Compared with the existing BH catalyst, the wear resistance of carburized gear steel is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is an optical microscope image of the carburized gear steel prepared in Example 1. DETAILED DESCRIPTION

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0052] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0053] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0054] The gear steel used in the following embodiments and comparative examples is 18Cr2Ni4WA gear steel, and the element composition and its mass percentage are C 0.183%, Si 0.33%, Mn 0.59%, P 0.004%, S 0.004%, Cr 1.57%, Ni 4.47%, W1.13%, and the balance is other inevitable impurities and iron. Example 1

[0055] A carburizing heat treatment method for gear steel, using a BH catalyst for carburizing treatment, comprises the following steps:

[0056] S1. The gear steel was carburized at 735 °C in a carburizing atmosphere of methanol, acetone and kerosene in a volume ratio of 1:2:3, with a carburizing atmosphere flow rate of 1.5 L / min, a carbon potential of 0.9 wt%, and a time of 0.3 h.

[0057] S2. The gear steel obtained in S1 was subjected to a carburizing treatment at 805 °C, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 3.0 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.8% of the total mass of the carburizing atmosphere, a carbon potential of 1.3 wt%, and a time of 1.0 h;

[0058] S3. The gear steel obtained in S2 was subjected to transitional carburizing treatment at 805 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 2.4 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.8% of the total mass of the carburizing atmosphere, a carbon potential of 1.2 wt%, and a time of 0.3 h;

[0059] S4. The gear steel obtained in S3 was subjected to diffusion period carburizing treatment at 805 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 1.7 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.8% of the total mass of the carburizing atmosphere, a carbon potential of 1.0 wt%, and a time of 1.0 h. After the diffusion period carburizing treatment, the steel was air-cooled to 20 ℃;

[0060] S5. The gear steel obtained in S4 was subjected to a high temperature tempering treatment at 620 °C for 2 h;

[0061] S6. The gear steel obtained in S5 was quenched at 805 °C for 50 min by oil quenching;

[0062] S7. The gear steel obtained in S6 was subjected to deep cryogenic treatment at -75 ℃ for 0.6 h, and then subjected to low temperature tempering treatment at 180 ℃ for 2 h to obtain carburized gear steel.

[0063] Wherein, BH permeation catalyst is prepared by the following method:

[0064] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 15.0%, 30.0%, 33.0% and 22.0%, and ground into uniform fine powder to obtain component A;

[0065] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0% and 82.0% to obtain component B;

[0066] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0067] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 67.0% and 33.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0068] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 52:26:20:2, to obtain the BH permeation catalyst. Example 2

[0069] A carburizing heat treatment method for gear steel, using a BH catalyst for carburizing treatment, comprises the following steps:

[0070] S1. The gear steel was carburized at 745 °C in a carburizing atmosphere of methanol, acetone and kerosene in a volume ratio of 1:2:3, with a carburizing atmosphere flow rate of 2.0 L / min, a carbon potential of 1.0 wt%, and a time of 0.5 h.

[0071] S2. The gear steel obtained in S1 was subjected to a carburizing treatment at 825 °C, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 4.0 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 3.2% of the total mass of the carburizing atmosphere, a carbon potential of 1.4 wt%, and a time of 1.7 h;

[0072] S3. The gear steel obtained in S2 was subjected to transitional carburizing treatment at 825 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 2.8 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 3.2% of the total mass of the carburizing atmosphere, a carbon potential of 1.3 wt%, and a time of 0.5 h;

[0073] S4. The gear steel obtained in S3 was subjected to diffusion period carburizing treatment at 825 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 2.2 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 3.2% of the total mass of the carburizing atmosphere, a carbon potential of 1.1 wt%, and a time of 1.5 h. After the diffusion period carburizing treatment, the steel was air-cooled to 30 ℃;

[0074] S5. The gear steel obtained in S4 was subjected to two high temperature tempering treatments at 625 °C, each time for 3 h;

[0075] S6. The gear steel obtained in S5 was quenched at 825 °C for 55 min by oil quenching;

[0076] S7. The gear steel obtained in S6 was subjected to deep cryogenic treatment at -90 °C for 0.9 h, and then subjected to low temperature tempering treatment at 195 °C for 2.8 h to obtain carburized gear steel.

[0077] Wherein, BH permeation catalyst is prepared by the following method:

[0078] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 25.0%, 25.0%, 30.0% and 20.0%, and ground into uniform fine powder to obtain component A;

[0079] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 23.0% and 77.0% to obtain component B;

[0080] (3) mixing sucrose and sodium carbonate in weight percentages of 63.0% and 37.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0081] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 74.0% and 26.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0082] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 57:21:21:1, to obtain the BH permeation catalyst. Example 3

[0083] A carburizing heat treatment method for gear steel, using a BH catalyst for carburizing treatment, comprises the following steps:

[0084] S1. The gear steel was carburized at 740 °C in a carburizing atmosphere of methanol, acetone and kerosene in a volume ratio of 1:2:3, with a carburizing atmosphere flow rate of 1.8 L / min, a carbon potential of 1.0 wt%, and a time of 0.4 h.

[0085] S2. The gear steel obtained in S1 was subjected to a carburizing treatment at 815 °C, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 3.5 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 2.5% of the total mass of the carburizing atmosphere, a carbon potential of 1.4 wt%, and a time of 1.3 h;

[0086] S3. The gear steel obtained in S2 was subjected to transitional carburizing treatment at 815 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 2.6 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 2.5% of the total mass of the carburizing atmosphere, a carbon potential of 1.3 wt%, and a time of 0.4 h;

[0087] S4. The gear steel obtained in S3 was subjected to diffusion period carburizing treatment at 815 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 2.0 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 2.5% of the total mass of the carburizing atmosphere, a carbon potential of 1.1 wt%, and a time of 1.2 h. After the diffusion period carburizing treatment, the steel was air-cooled to 25 ℃;

[0088] S5. The gear steel obtained in S4 was subjected to a high temperature tempering treatment at 625 °C for 2 h;

[0089] S6. The gear steel obtained in S5 was quenched at 815 °C for 50 min by oil quenching;

[0090] S7. The gear steel obtained in S6 was subjected to deep cryogenic treatment at -85 ℃ for 0.7 h, and then subjected to low temperature tempering treatment at 185 ℃ for 2.6 h to obtain carburized gear steel.

[0091] Wherein, BH permeation catalyst is prepared by the following method:

[0092] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in a weight percentage of 20.0%, 27.5%, 31.5% and 21.0%, and ground into uniform fine powder to obtain component A;

[0093] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 20.5% and 79.5% to obtain component B;

[0094] (3) mixing sucrose and sodium carbonate in weight percentages of 60.0% and 40.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0095] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in an amount of 70.0% by mass and 30.0% by mass to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0096] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 55:23:20.5:1.5, to obtain the BH permeation catalyst. Comparative Example 1

[0097] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0098] (1) lanthanum oxide, ferric chloride and sodium oxide are mixed in a weight percentage of 15.0%, 30.0% and 55.0%, and ground into uniform fine powder to obtain component A;

[0099] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0% and 82.0% to obtain component B;

[0100] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0101] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 67.0% and 33.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0102] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 52:26:20:2, to obtain the BH permeation catalyst. Comparative Example 2

[0103] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0104] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 15.0%, 30.0%, 33.0% and 22.0%, and ground into uniform fine powder to obtain component A;

[0105] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 15.0% and 85.0% to obtain component B;

[0106] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0107] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 67.0% and 33.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0108] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 52:26:20:2, to obtain the BH permeation catalyst. Comparative Example 3

[0109] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0110] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 15.0%, 30.0%, 33.0% and 22.0%, and ground into uniform fine powder to obtain component A;

[0111] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0% and 82.0% to obtain component B;

[0112] (3) mixing maltose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0113] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 67.0% and 33.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0114] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 52:26:20:2, to obtain the BH permeation catalyst. Comparative Example 4

[0115] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0116] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 15.0%, 30.0%, 33.0% and 22.0%, and ground into uniform fine powder to obtain component A;

[0117] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0% and 82.0% to obtain component B;

[0118] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0119] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 67.0% and 33.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0120] (5) Mixing component A, component B, component C solution and component D solution, wherein the mass ratio of component C in the component A, component B, component C solution and component D in the component D solution is 48:18:32:2, to obtain the BH permeation catalyst. Comparative Example 5

[0121] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0122] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in weight percentages of 15.0%, 30.0%, 33.0% and 22.0%, and ground into uniform fine powder to obtain component A;

[0123] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 18.0% and 82.0% to obtain component B;

[0124] (3) mixing sucrose and sodium carbonate in weight percentages of 56.0% and 44.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0125] (4) Mixing the solutions of component A, component B and component C, wherein the mass ratio of component C in the solutions of component A, component B and component C is 54:26:20, to obtain the BH permeation catalyst. Comparative Example 6

[0126] A carburizing heat treatment method for gear steel is basically the same as Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0127] (1) Ferric chloride and sodium oxide are mixed in a mass percentage of 30.0% and 70.0%, and ground into uniform fine powder to obtain component A; component B is argon microspheres; sodium carbonate is component C, and component C is dissolved in methanol to obtain a component C solution;

[0128] (2) Mixing component A, component B and component C solutions, wherein the mass ratio of component C in the component A, component B and component C solutions is 52:26:22, to obtain the BH permeation catalyst. Comparative Example 7

[0129] A carburizing heat treatment method for gear steel, using a BH catalyst for carburizing treatment, is basically the same as Example 1, except that: in S2-S4, the temperatures of the intensive carburizing treatment, the transitional carburizing treatment, and the diffusion period carburizing treatment are all replaced with 795°C. Comparative Example 8

[0130] A carburizing heat treatment method for gear steel, using a BH catalyst for carburizing treatment, is basically the same as Example 1, except that: in S2-S4, the amount of BH catalyst (excluding methanol used in preparing the BH catalyst) in the strong carburizing period carburizing treatment, transition period carburizing treatment and diffusion period carburizing treatment is 1.5% of the total mass of the carburizing atmosphere.

[0131] Test Example 1

[0132] The carburized gear steel prepared in Example 1 was characterized. The characterization results are as follows: Figure 1 As shown. Figure 1 It can be seen that the surface structure is composed of martensite, retained austenite and carbide, which can effectively improve the wear resistance of the surface.

[0133] Test Example 2

[0134] The wear resistance (average friction coefficient and wear volume) of the carburized gear steels prepared in Examples 1-3 and Comparative Examples 1-8 was tested. The test method was based on the standard "GB / T 12444-2006 Metallic Material Wear Test Method Test Ring-Test Block Sliding Wear Test". The test results are shown in Table 1:

[0135] Table 1

[0136]

[0137] It can be seen from Table 1 that the carburized gear steel obtained in the embodiment has good wear resistance, an average friction coefficient of 0.32-0.35, and a wear volume of 0.72-0.77 mm 3 .

[0138] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 1 are higher than those in Example 1. This is because in Comparative Example 1, potassium oxide K2O is completely replaced by sodium oxide Na2O, resulting in the incomplete decomposition of the carburizing agent at a lower temperature, the reduced activity of carbon atoms and insufficient diffusion, and the significantly reduced wear resistance.

[0139] Comparing the data of Example 1 and Comparative Example 2, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 2 are higher than those in Example 1. This is because the mass percentages of trinitrotoluene TNT and argon microspheres Ar are replaced with 15.0% and 85.0% in Comparative Example 2, and the shock waves intermittently generated during the carburizing process are not enough to destroy the gas film layer, the contact opportunity between the active components and the workpiece surface is reduced, and the wear resistance is significantly reduced.

[0140] Comparing the data of Example 1 and Comparative Example 3, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 3 are higher than those in Example 1. This is because all sucrose is replaced by maltose in Comparative Example 3, which changes the decomposition process of the penetrant, reduces the activity of carbon atoms and diffuses insufficiently, and significantly reduces the wear resistance.

[0141] Comparing the data of Example 1 and Comparative Example 4, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 4 are higher than those in Example 1. This is because the mass ratio of component A to component B is reduced in Comparative Example 4, resulting in a decrease in the catalytic effect of composite decomposition during carburization, and the intermittent shock wave is insufficient to destroy the air film layer, and the wear resistance is significantly reduced.

[0142] Comparing the data of Example 1 and Comparative Example 5, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 5 are higher than those in Example 1. This is because no surfactant and dispersant are added to the catalyst, which leads to the easy agglomeration of particles during carburization, weakening the catalytic effect and significantly reducing the wear resistance.

[0143] Comparing the data of Examples 1-3 and Comparative Example 6, it can be seen that the average friction coefficient of the carburized gear steel prepared in the examples is reduced by 35.2-40.7%, the wear volume is reduced by 35.3-39.5%, and the wear resistance is greatly improved. This is because Examples 1-3 use a more sophisticated composite catalyst system, accurately control the ratio of rare earth elements, transition metals and two alkaline oxides, and also introduce a new type of controlled release shock wave material as well as surfactants and dispersants to achieve a low-temperature, fast and efficient carburizing process, significantly improve the carburizing efficiency and carburized layer quality, reduce workpiece deformation, optimize the organization, and greatly improve wear resistance.

[0144] Comparing the data of Example 1 and Comparative Example 7, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 7 are higher than those in Example 1. This is because the carburizing temperature in the strong carburizing period, transition period and diffusion period is replaced with 795°C in Comparative Example 7. The lower carburizing temperature causes insufficient diffusion of carbon atoms, and the wear resistance is significantly reduced.

[0145] Comparing the data of Example 1 and Comparative Example 8, it can be seen that the average friction coefficient and wear volume of the carburized gear steel prepared in Comparative Example 8 are higher than those in Example 1. This is because in Comparative Example 8, the amount of the catalyst used in the carburizing treatment process during the strong carburizing period, transition period and diffusion period is replaced with 1.5% of the total mass of the carburizing atmosphere, resulting in insufficient catalytic effect of the catalyst and significantly reduced wear resistance.

[0146] In summary, the present invention adopts BH catalyst to carry out carburizing heat treatment of gear steel, which can realize low-temperature, rapid and efficient carburizing process, significantly improve carburizing efficiency and carburized layer quality, reduce workpiece deformation, optimize organization, and improve the overall performance of parts.

[0147] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A BH penetration catalyst, characterized in that The BH permeation catalyst comprises the following components in percentage by mass: component A 52.0-57.0%, component B 21.0-26.0%, component C 20.0-21.0%, component D 1.0-2.0%; in, Component A includes the following components in percentage by mass: 15.0-25.0% lanthanum oxide, 25.0-30.0% ferric chloride, 30.0-33.0% sodium oxide, and 20.0-22.0% potassium oxide; Component B includes the following components in percentage by mass: 18.0-23.0% trinitrotoluene, 77.0-82.0% argon microspheres; Component C includes the following components in percentage by mass: sucrose 56.0-63.0%, sodium carbonate 37.0-44.0%; Component D includes the following components in percentage by mass: 67.0-74.0% of surfactant and 26.0-33.0% of dispersant.

2. The BH penetration catalyst according to claim 1, characterized in that The surfactant is sodium dodecylbenzene sulfonate, and the dispersant is polymethylpyrrolidone.

3. A method for preparing the BH penetration catalyst according to claim 1 or 2, characterized in that: The following steps are involved: (1) mixing lanthanum oxide, ferric chloride, sodium oxide and potassium oxide in proportion to obtain component A; (2) mixing trinitrotoluene and argon microspheres according to a certain proportion to obtain component B; (3) mixing sucrose and sodium carbonate according to a certain proportion to obtain component C; (4) mixing the surfactant and the dispersant according to a certain proportion to obtain component D; (5) Component A, component B, component C and component D are mixed according to a certain proportion to obtain the BH permeation catalyst.

4. Use of the BH catalyst according to claim 1 or 2 in carburizing heat treatment of gear steel.

5. A method for carburizing heat treatment of gear steel, characterized in that: Carburizing treatment using the BH catalyst according to claim 1 or 2 comprises the following steps: S1. Carburize the gear steel at 735-745 °C during the isothermal period, with a carburizing atmosphere flow rate of 1.5-2.0 L / min and a carbon potential of 0.9-1.0 wt%; S2. The gear steel obtained in S1 was subjected to a strong carburizing treatment at 805-825 °C, the carburizing atmosphere flow rate was 3.0-4.0 L / min, the amount of BH catalyst was 1.8-3.2% of the total mass of the carburizing atmosphere, and the carbon potential was 1.3-1.4 wt%; S3. The gear steel obtained in S2 was subjected to transitional carburizing treatment at 805-825 °C, the carburizing atmosphere flow rate was 2.4-2.8 L / min, the amount of BH catalyst was 1.8-3.2% of the total mass of the carburizing atmosphere, and the carbon potential was 1.2-1.3 wt%; S4. The gear steel obtained in S3 is subjected to diffusion period carburizing treatment at 805-825 ℃, the carburizing atmosphere flow rate is 1.7-2.2L / min, the amount of BH catalyst is 1.8-3.2% of the total mass of the carburizing atmosphere, the carbon potential is 1.0-1.1 wt%, and the diffusion period carburizing treatment is followed by air cooling to 20-30 ℃; S5. The gear steel obtained in S4 is subjected to high temperature tempering treatment at 620-625°C; S6. The gear steel obtained in S5 is quenched at 805-825°C; S7. The gear steel obtained in S6 is subjected to deep cryogenic treatment at -75°C to -90°C, and then subjected to low temperature tempering treatment at 180-195°C to obtain carburized gear steel.

6. The method for carburizing heat treatment of gear steel according to claim 5, characterized in that: In S1-S4, the carburizing atmosphere is composed of methanol, acetone and kerosene, and the volume ratio of methanol, acetone and kerosene is 1:(1.5-2.5):(2.5-3.5).

7. The carburizing heat treatment method for gear steel according to claim 5, characterized in that: In S2, the time of the carburizing treatment in the strong carburizing period is 1.0-1.7 h; in S3, the time of the carburizing treatment in the transition period is 0.3-0.5 h; in S4, the time of the carburizing treatment in the diffusion period is 1.0-1.5 h.

8. The carburizing heat treatment method for gear steel according to claim 5, characterized in that: In S5, 1-2 high temperature tempering treatments are performed, and the time for each high temperature tempering treatment is 2-3 h.

9. The method for carburizing heat treatment of gear steel according to claim 5, characterized in that: In S6, the quenching treatment time is 50-55 min.

10. The method for carburizing heat treatment of gear steel according to claim 5, characterized in that: In S7, the time of the deep cryogenic treatment is 0.6-0.9 h, and the time of the low temperature tempering treatment is 2-2.8 h.

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