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

Abstract

The present invention discloses a BH catalyst and a preparation method thereof and a carbonitriding heat treatment method for gear steel. The BH catalyst includes four components, component A includes lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide, component B includes trinitrotoluene and argon microspheres, component C includes sucrose and sodium carbonate, and component D includes a surfactant and a dispersant. The present invention adopts the BH catalyst to carry out the carbonitriding heat treatment process of gear steel, which can realize a fast and efficient carbonitriding process at a relatively low temperature, significantly reducing energy consumption and workpiece deformation, while optimizing the organizational structure and improving the wear resistance of parts. The wear resistance of the carbonitriding gear steel prepared by the present invention is greatly improved, with an average friction coefficient of 0.28-0.30 and a wear volume of 0.55-0.58 mm <supgt;3< / supgt;。

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 carbonitriding heat treatment method for gear steel. Background Art

[0002] As an important surface modification process, carbonitriding has long played a key role in enhancing the wear resistance, fatigue resistance and corrosion resistance of metal materials. The traditional carbonitriding process often needs to be carried out under relatively high temperature conditions. This high-temperature treatment not only brings high energy consumption, but also easily causes thermal deformation problems of the workpiece, which in turn has an adverse effect on the dimensional accuracy and overall performance of the final product. In addition, the decomposition efficiency of traditional penetrants is low and the penetration rate is slow, which makes it difficult to meet the current urgent needs of industrial production for high efficiency, energy saving and environmental protection. These limitations have largely restricted the widespread application and further development of traditional carbonitriding processes.

[0003] In recent years, researchers have been committed to exploring and developing new carbonitriding technologies in order to overcome the shortcomings of traditional processes. Among them, BH catalytic infiltration technology, as a chemical heat treatment method, has received widespread attention due to its unique technical advantages. The core of BH catalytic infiltration technology is to add trace catalysts to the infiltrant, which can effectively promote the full decomposition of the infiltrant at a relatively low temperature, thereby releasing a large number of highly active carbon atoms and nitrogen atoms. These highly active atoms can quickly diffuse on the surface of the workpiece to form a uniform and dense infiltration layer, which significantly improves the infiltration rate and optimizes the quality of the infiltration layer.

[0004] However, although BH catalytic infiltration technology has shown excellent performance in increasing the infiltration rate and improving the quality of the infiltration layer, it still faces some challenges in its actual application, such as the selection and ratio of the catalyst, which requires extremely precise control to ensure the efficient decomposition of the infiltrant and the uniform distribution of the infiltration layer. In addition, the full play of BH catalytic infiltration technology needs to be combined with a specific carbonitriding process to achieve the best treatment effect.

[0005] Therefore, the development of a new and efficient BH catalyst and its matching gear steel carbonitriding heat treatment method is of great significance for improving the infiltration rate, optimizing the quality of the infiltration layer, reducing workpiece deformation and energy consumption, and reducing environmental pollution. Summary of the invention

[0006] In order to solve the problems of slow infiltration rate, uneven infiltration layer, insufficient surface wear resistance, etc. in the prior art, the purpose of the present invention is to provide a BH catalyst and a preparation method thereof and a carbonitriding heat treatment method for gear steel. The BH catalyst can achieve efficient, energy-saving and low-deformation carbonitriding heat treatment of gear steel.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A BH penetration catalyst, comprising the following components in percentage by mass: component A 62.0-65.0%, component B 27.0-30.0%, component C 6.0-7.0%, component D 1.0-2.0%; wherein,

[0009] Component A includes the following components in mass percentage: lanthanum oxide (La2O3) 30.0-35.0%, ferric chloride (FeCl3) 20.0-25.0%, nickel trioxide (Ni2O3) 10.0-12.0%, sodium oxide (Na2O) 10.0-17.0%, potassium oxide (K2O) 18.0-23.0%;

[0010] Component B includes the following components in percentage by mass: trinitrotoluene (TNT) 25.0-29.0%, argon microspheres (Ar) 71.0-75.0%;

[0011] Component C includes the following components in percentage by weight: sucrose (C 12 H 22 O 11 ) 46.0-51.0%, sodium carbonate (Na2CO3) 49.0-54.0%;

[0012] Component D includes the following components in percentage by mass: 52.0-59.0% of surfactant and 41.0-48.0% of dispersant.

[0013] 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.

[0014] Furthermore, the argon microspheres are prepared by encapsulating argon in a silicon dioxide (SiO2) shell.

[0015] Furthermore, the thickness of the silicon dioxide shell is 0.13-0.16 mm.

[0016] Furthermore, the particle size of the argon microspheres is 0.8-1.2 mm.

[0017] Furthermore, the surfactant is sodium dodecylbenzene sulfonate (SDBS), and the dispersant is polymethylpyrrolidone (PVP).

[0018] A method for preparing the above-mentioned BH penetration catalyst comprises the following steps:

[0019] (1) mixing lanthanum oxide, ferric chloride, nickel oxide, sodium oxide and potassium oxide in proportion to obtain component A;

[0020] (2) mixing trinitrotoluene and argon microspheres according to a certain proportion to obtain component B;

[0021] (3) mixing sucrose and sodium carbonate according to a certain proportion to obtain component C;

[0022] (4) mixing the surfactant and the dispersant according to a certain proportion to obtain component D;

[0023] (5) Component A, component B, component C and component D are mixed according to a certain proportion to obtain the BH permeation catalyst.

[0024] In a specific embodiment, the preparation method comprises the following steps:

[0025] (1) mixing lanthanum oxide, ferric chloride, sodium oxide and potassium oxide in weight percentages of 30.0-35.0%, 20.0-25.0%, 10.0-12.0%, 10.0-17.0% and 18.0-23.0%, and grinding into uniform fine powder to obtain component A;

[0026] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0-29.0% and 71.0-75.0% to obtain component B;

[0027] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0-51.0% and 49.0-54.0% to obtain component C, and dissolving component C in a solvent to obtain a component C solution;

[0028] (4) mixing a surfactant and a dispersant in an amount of 52.0-59.0% by weight and 41.0-48.0% by weight to obtain a component D, and dissolving the component D in a solvent to obtain a component D solution;

[0029] (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 (62-65):(27-30):(6-7):(1-2), to obtain the BH permeation catalyst.

[0030] Furthermore, the solvent is methanol, and the BH catalyst reaches a saturated state in the solvent.

[0031] The present invention also protects the use of the above-mentioned BH catalyst in the carbonitriding heat treatment of gear steel.

[0032] A carbonitriding heat treatment method for gear steel, using the above-mentioned BH catalyst for carbonitriding treatment, comprises the following steps:

[0033] S1. Carry out carbonitriding treatment on gear steel at 775-790 ℃, the carburizing atmosphere flow rate is 4.5-5.0L / min, the amount of BH catalyst is 1.4-1.7% of the total mass of the carburizing atmosphere, the carbon potential is 1.5-1.6 wt%, and the ammonia flow rate is 4.0-4.8 L / min;

[0034] S2. The gear steel obtained in S1 was subjected to diffusion carbonitriding treatment at 775-790 ℃, the carburizing atmosphere flow rate was 2.6-3.0 L / min, the amount of BH catalyst was 1.4-1.7% of the total mass of the carburizing atmosphere, the carbon potential was 1.2-1.3 wt%, the ammonia flow rate was 3.5-3.9 L / min, and the diffusion carbonitriding treatment was followed by air cooling to 20-30 ℃;

[0035] S3. The gear steel obtained in S2 is subjected to high temperature tempering treatment at 610-615 °C;

[0036] S4. The gear steel obtained in S3 is quenched at 790-800°C;

[0037] S5. The gear steel obtained in S4 is subjected to deep cryogenic treatment at -60°C to -70°C, and then subjected to low temperature tempering treatment at 165-175°C to obtain carbonitriding gear steel.

[0038] Furthermore, in S1 and S2, the carburizing atmosphere consists of methanol, acetone and kerosene, and the volume ratio of methanol, acetone and kerosene is 1:(1.5-2.5):(2.5-3.5).

[0039] Furthermore, in S1, the time of the carbonitriding treatment during the strong permeation period is 1.1-1.4 h.

[0040] Furthermore, in S2, the time of the carbonitriding treatment during the diffusion period is 0.7-0.9 h.

[0041] Furthermore, in S3, the high temperature tempering treatment time is 1.5-2.5 h.

[0042] Furthermore, in S4, the quenching treatment time is 60-65 min.

[0043] Furthermore, in S4, the quenching treatment is performed by oil quenching.

[0044] Furthermore, in S5, the time of the deep cryogenic treatment is 0.7-0.9 h, and the time of the low temperature tempering treatment is 1.7-2.0 h.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The BH catalyst provided by the present invention achieves a significant improvement in catalytic efficiency. By precisely controlling the high-efficiency composite decomposition catalyst, the substance that intermittently generates shock waves, the chemical substance that changes the decomposition process of the penetrant, and the ratio of the surfactant and the dispersant, a large number of highly active carbon atoms and nitrogen atoms are generated. These active atoms diffuse rapidly on the surface of the workpiece to form a uniform penetration layer, thereby significantly improving the penetration rate and penetration layer quality.

[0047] (2) The BH catalyst provided by the present invention introduces a controllable release shock wave material, which is combined with inert gas microspheres encapsulated in a silica shell. This combination can produce a more uniform and strong shock wave effect during the carbonitriding process, effectively destroy the gas film barrier on the surface of the workpiece, and promote the deep contact between the carbonitriding medium and the workpiece surface. In addition, surfactants and dispersants with hydrophilic and lipophilic properties, which can adjust the surface tension between different phases and promote compatibility and dispersibility, are added. These additives can construct steric hindrance or produce electrostatic repulsion effects in the medium, effectively preventing the agglomeration of particles.

[0048] (3) The present invention uses BH catalyst to carry out carbonitriding heat treatment process of gear steel, which can realize fast and efficient carbonitriding process at low temperature, significantly reduce energy consumption and workpiece deformation, optimize the organizational structure and improve the wear resistance of parts. The wear resistance of carbonitriding gear steel prepared by the present invention is greatly improved, with an average friction coefficient of 0.28-0.30 and a wear volume of 0.55-0.58 mm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is an optical microscope image of the carbonitrided gear steel prepared in Example 1. DETAILED DESCRIPTION

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 0.182%, Si 0.34%, Mn 0.58%, P 0.004%, S 0.003%, Cr 1.55%, Ni 4.49%, W1.12%, and the balance is other inevitable impurities and iron. Example 1

[0054] A carbonitriding heat treatment method for gear steel, using a BH catalyst for carbonitriding treatment, comprises the following steps:

[0055] S1. The gear steel was subjected to a carbonitriding treatment at 775 ℃, using a carburizing atmosphere of methanol, acetone and kerosene mixed in a volume ratio of 1:2:3, a carburizing atmosphere flow rate of 4.5 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.4% of the total mass of the carburizing atmosphere, a carbon potential of 1.5 wt%, an ammonia flow rate of 4.0 L / min, and a time of 1.1 h;

[0056] S2. The gear steel obtained in S1 was subjected to diffusion-period carbonitriding treatment at 775 ℃, 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 1.4% of the total mass of the carburizing atmosphere, a carbon potential of 1.2 wt%, an ammonia flow rate of 3.5 L / min, a time of 0.7 h, and air-cooled to 20 ℃ after the diffusion-period carbonitriding treatment;

[0057] S3. The gear steel obtained in S2 was subjected to high temperature tempering treatment at 610 °C for 1.5 h;

[0058] S4. The gear steel obtained in S3 is quenched at 790 °C for 60 min by oil quenching;

[0059] S5. The gear steel obtained in S4 was cryogenically treated at -60 °C for 0.7 h, and then low-temperature tempered at 165 °C for 1.7 h to obtain carbonitrided gear steel.

[0060] Wherein, BH permeation catalyst is prepared by the following method:

[0061] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 25.0%, 10.0%, 17.0% and 18.0% by weight, and ground into uniform fine powder to obtain component A;

[0062] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0% and 75.0% to obtain component B;

[0063] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0064] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 52.0% and 48.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0065] (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 62:30:6:2, to obtain the BH permeation catalyst. Example 2

[0066] A carbonitriding heat treatment method for gear steel, using a BH catalyst for carbonitriding treatment, comprises the following steps:

[0067] S1. The gear steel was subjected to a carbonitriding treatment at 790 °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 5.0 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.7% of the total mass of the carburizing atmosphere, a carbon potential of 1.6 wt%, an ammonia flow rate of 4.8 L / min, and a time of 1.4 h;

[0068] S2. The gear steel obtained in S1 was subjected to diffusion-period carbonitriding at 790 °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 1.7% of the total mass of the carburizing atmosphere, a carbon potential of 1.3 wt%, an ammonia flow rate of 3.9 L / min, a time of 0.9 h, and air-cooled to 25 °C after the diffusion-period carbonitriding treatment;

[0069] S3. The gear steel obtained in S2 was subjected to high temperature tempering treatment at 610 °C for 2.5 h;

[0070] S4. The gear steel obtained in S3 is quenched at 800 °C for 65 min by oil quenching;

[0071] S5. The gear steel obtained in S4 was cryogenically treated at -70 °C for 0.9 h, and then low-temperature tempered at 175 °C for 2.0 h to obtain carbonitrided gear steel.

[0072] Wherein, BH permeation catalyst is prepared by the following method:

[0073] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 20.0%, 12.0%, 10.0% and 23.0% by weight, and ground into uniform fine powder to obtain component A;

[0074] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 29.0% and 71.0% to obtain component B;

[0075] (3) mixing sucrose and sodium carbonate in weight percentages of 51.0% and 49.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0076] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 59.0% and 41.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0077] (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 65:27:7:1, to obtain the BH permeation catalyst. Example 3

[0078] A carbonitriding heat treatment method for gear steel, using a BH catalyst for carbonitriding treatment, comprises the following steps:

[0079] S1. The gear steel was subjected to a carbonitriding treatment at 780 °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 4.8 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.5% of the total mass of the carburizing atmosphere, a carbon potential of 1.5 wt%, an ammonia flow rate of 4.4 L / min, and a time of 1.3 h;

[0080] S2. The gear steel obtained in S1 was subjected to diffusion-period carbonitriding at 780 °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 2.8 L / min, a BH catalyst (excluding the methanol used in the preparation of the BH catalyst) of 1.5% of the total mass of the carburizing atmosphere, a carbon potential of 1.2 wt%, an ammonia flow rate of 3.7 L / min, and a time of 0.8 h. After the diffusion-period carbonitriding treatment, the steel was air-cooled to 30 °C.

[0081] S3. The gear steel obtained in S2 was subjected to high temperature tempering treatment at 610 °C for 2 h;

[0082] S4. The gear steel obtained in S3 is quenched at 795 °C for 60 min by oil quenching.

[0083] S5. The gear steel obtained in S4 was cryogenically treated at -65 °C for 0.8 h, and then low-temperature tempered at 170 °C for 1.8 h to obtain carbonitrided gear steel.

[0084] Wherein, BH permeation catalyst is prepared by the following method:

[0085] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 32.0%, 23.0%, 11.0%, 14.0% and 20.0% by weight, and ground into uniform fine powder to obtain component A;

[0086] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 27.0% and 73.0% to obtain component B;

[0087] (3) mixing sucrose and sodium carbonate in weight percentages of 48.0% and 52.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0088] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in a weight percentage of 55.0% and 45.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0089] (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 64:28:6.5:1.5, to obtain the BH permeation catalyst. Comparative Example 1

[0090] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0091] (1) lanthanum oxide, ferric chloride, sodium oxide and potassium oxide are mixed in a weight percentage of 30.0%, 25.0%, 17.0% and 28.0%, and ground into uniform fine powder to obtain component A;

[0092] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0% and 75.0% to obtain component B;

[0093] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0094] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 52.0% and 48.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0095] (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 62:30:6:2, to obtain the BH permeation catalyst. Comparative Example 2

[0096] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0097] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 25.0%, 10.0%, 17.0% and 18.0% by weight, and ground into uniform fine powder to obtain component A;

[0098] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 20.0% and 80.0% to obtain component B;

[0099] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0100] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 52.0% and 48.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0101] (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 62:30:6:2, to obtain the BH permeation catalyst. Comparative Example 3

[0102] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0103] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 25.0%, 10.0%, 17.0% and 18.0% by weight, and ground into uniform fine powder to obtain component A;

[0104] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0% and 75.0% to obtain component B;

[0105] (3) mixing maltose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0106] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 52.0% and 48.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0107] (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 62:30:6:2, to obtain the BH permeation catalyst. Comparative Example 4

[0108] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0109] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 25.0%, 10.0%, 17.0% and 18.0% by weight, and ground into uniform fine powder to obtain component A;

[0110] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0% and 75.0% to obtain component B;

[0111] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0112] (4) mixing sodium dodecylbenzene sulfonate and polymethylpyrrolidone in weight percentages of 52.0% and 48.0% to obtain component D, and dissolving component D in methanol to obtain a component D solution;

[0113] (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 58:24:16:2, to obtain the BH permeation catalyst. Comparative Example 5

[0114] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0115] (1) lanthanum oxide, ferric chloride, nickel trioxide, sodium oxide and potassium oxide are mixed in the amounts of 30.0%, 25.0%, 10.0%, 17.0% and 18.0% by weight, and ground into uniform fine powder to obtain component A;

[0116] (2) uniformly mixing trinitrotoluene and argon microspheres in weight percentages of 25.0% and 75.0% to obtain component B;

[0117] (3) mixing sucrose and sodium carbonate in weight percentages of 46.0% and 54.0% to obtain component C, and dissolving component C in methanol to obtain a component C solution;

[0118] (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 64:30:6, to obtain the BH permeation catalyst. Comparative Example 6

[0119] A carbonitriding heat treatment method for gear steel is basically the same as that of Example 1, except that a different BH catalyst is used, and the BH catalyst is prepared by the following method:

[0120] (1) Ferric chloride and sodium oxide are mixed in a weight percentage of 25.0% and 75.0%, 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;

[0121] (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 62:30:8, to obtain the BH permeation catalyst. Comparative Example 7

[0122] A carbonitriding heat treatment method for gear steel, using a BH catalyst for carbonitriding treatment, is basically the same as Example 1, except that: in S1 and S2, the temperature of the carbonitriding treatment in the intensive period and the carbonitriding treatment in the diffusion period are both replaced with 765°C. Comparative Example 8

[0123] A method for carbonitriding heat treatment of gear steel, using a BH catalyst for carbonitriding treatment, is basically the same as Example 1, except that in S1 and S2, the amount of BH catalyst (excluding methanol used in preparing the BH catalyst) used in the strong carburizing period carbonitriding treatment and the diffusion period carbonitriding treatment is 1.2% of the total mass of the carburizing atmosphere.

[0124] Test Example 1

[0125] The carbonitriding 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 nitrogen-containing martensite, retained austenite and carbide, which can effectively improve the wear resistance of the surface.

[0126] Test Example 2

[0127] The wear resistance (average friction coefficient and wear volume) of the carbonitrided 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:

[0128] Table 1

[0129]

[0130] It can be seen from Table 1 that the carbonitriding gear steel obtained in the embodiment has good wear resistance, an average friction coefficient of 0.28-0.30, and a wear volume of 0.55-0.58 mm 3 .

[0131] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel in Comparative Example 1 are higher than those in Example 1. This is because in Comparative Example 1, all nickel trioxide is replaced by potassium oxide, resulting in the failure of the infiltrant to fully decompose at a lower temperature, the activity of carbon and nitrogen atoms is reduced, and the diffusion is insufficient, and the wear resistance is significantly reduced.

[0132] Comparing the data of Example 1 and Comparative Example 2, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel in Comparative Example 2 are higher than those in Example 1. This is because the mass percentages of trinitrotoluene and argon microspheres in Comparative Example 2 are replaced with 20.0% and 80.0%, respectively, and the shock waves intermittently generated during the carbonitriding process are insufficient 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.

[0133] Comparing the data of Example 1 and Comparative Example 3, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel in Comparative Example 3 are higher than those in Example 1. This is because in Comparative Example 3, all sucrose is replaced by maltose, which changes the decomposition process of the penetrant, reduces the activity of carbon atoms and nitrogen atoms, and diffuses insufficiently, and significantly reduces the wear resistance.

[0134] Comparing the data of Example 1 and Comparative Example 4, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel 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 carburizing, and the intermittent shock wave is insufficient to destroy the air film layer, and the wear resistance is significantly reduced.

[0135] Comparing the data of Example 1 and Comparative Example 5, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel in Comparative Example 5 are higher than those in Example 1. This is because no surfactant and dispersant are added in Comparative Example 5, which leads to the easy agglomeration of particles during the carbonitriding process, weakening the catalytic effect, and significantly reducing the wear resistance.

[0136] Comparing the data of Examples 1-3 and Comparative Example 6, it can be seen that the average friction coefficient of the gear steel prepared in the examples is reduced by 46.4-50.0%, the wear volume is reduced by 49.6-52.2%, 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, two 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 carbonitriding process, significantly improve the carbonitriding efficiency and the quality of the infiltration layer, reduce workpiece deformation, optimize the organization, and greatly improve the wear resistance.

[0137] Comparing the data of Example 1 and Comparative Example 7, it can be seen that the average friction coefficient and wear volume of the carbonitriding gear steel in Comparative Example 7 are higher than those in Example 1. This is because the temperature of the carbonitriding treatment in the intensive permeation period and the diffusion period is replaced with 765°C in Comparative Example 7. The lower carbonitriding temperature causes insufficient diffusion of carbon and nitrogen atoms, and the wear resistance is significantly reduced.

[0138] Comparing the data of Example 1 and Comparative Example 8, it can be seen that the average friction coefficient and wear volume of the carbonitrided gear steel 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 carbonitriding treatment during the strong carburizing period and the diffusion period was replaced with 1.2% of the total mass of the carburizing atmosphere, resulting in insufficient catalytic effect of the catalyst and a significant reduction in wear resistance.

[0139] In summary, the present invention adopts BH catalyst to carry out carbonitriding heat treatment process of gear steel, which can realize fast and efficient carbonitriding process at lower temperature, significantly reduce energy consumption and workpiece deformation, optimize the organizational structure and improve the wear resistance of parts.

[0140] 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 penetration catalyst comprises the following components in mass percentage: component A 62.0-65.0%, component B 27.0-30.0%, component C 6.0-7.0%, component D 1.0-2.0%; in, Component A includes the following components in percentage by mass: 30.0-35.0% lanthanum oxide, 20.0-25.0% ferric chloride, 10.0-12.0% nickel oxide, 10.0-17.0% sodium oxide, and 18.0-23.0% potassium oxide; Component B includes the following components in percentage by mass: 25.0-29.0% trinitrotoluene, 71.0-75.0% argon microspheres; Component C includes the following components in percentage by mass: sucrose 46.0-51.0%, sodium carbonate 49.0-54.0%; Component D includes the following components in percentage by mass: 52.0-59.0% of surfactant and 41.0-48.0% of dispersant.

2. The BH penetration catalyst according to claim 1, characterized in that The argon microspheres are prepared by encapsulating argon gas in a silicon dioxide shell.

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

4. A method for preparing the BH penetration catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) mixing lanthanum oxide, ferric chloride, nickel oxide, 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 in 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.

5. Use of the BH catalyst according to any one of claims 1 to 3 in carbonitriding heat treatment of gear steel.

6. A carbonitriding heat treatment method for gear steel, characterized in that: The carbonitriding treatment is carried out using the BH catalyst according to any one of claims 1 to 3, comprising the following steps: S1. Carry out carbonitriding treatment of gear steel at 775-790 ℃, the carburizing atmosphere flow rate is 4.5-5.0 L / min, the amount of BH catalyst is 1.4-1.7% of the total mass of the carburizing atmosphere, the carbon potential is 1.5-1.6 wt%, and the ammonia flow rate is 4.0-4.8 L / min; S2. The gear steel obtained in S1 was subjected to diffusion carbonitriding treatment at 775-790 ℃, the carburizing atmosphere flow rate was 2.6-3.0 L / min, the amount of BH catalyst was 1.4-1.7% of the total mass of the carburizing atmosphere, the carbon potential was 1.2-1.3 wt%, the ammonia flow rate was 3.5-3.9 L / min, and the diffusion carbonitriding treatment was followed by air cooling to 20-30 ℃; S3. The gear steel obtained in S2 is subjected to high temperature tempering treatment at 610-615 °C; S4. The gear steel obtained in S3 is quenched at 790-800°C; S5. The gear steel obtained in S4 is subjected to deep cryogenic treatment at -60°C to -70°C, and then subjected to low temperature tempering treatment at 165-175°C to obtain carbonitriding gear steel.

7. The carbonitriding heat treatment method for gear steel according to claim 6, 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).

8. The carbonitriding heat treatment method for gear steel according to claim 6, characterized in that: In S1, the carbonitriding treatment time during the intensive stage is 1.1-1.4 h; and in S2, the carbonitriding treatment time during the diffusion stage is 0.7-0.9 h.

9. The carbonitriding heat treatment method for gear steel according to claim 6, characterized in that: In S3, the high temperature tempering treatment time is 1.5-2.5 h.

10. The carbonitriding heat treatment method for gear steel according to claim 6, characterized in that: In S5, the time of the deep cryogenic treatment is 0.7-0.9 h, and the time of the low temperature tempering treatment is 1.7-2.0 h.

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