A method for enhancing the wear resistance of clutch tooth surfaces

Abstract

This invention belongs to the field of powder metallurgy component surface strengthening technology, aiming to solve the problem that existing clutch tooth surface strengthening processes struggle to simultaneously achieve geometric accuracy, wear resistance, and process efficiency. This invention provides a method for strengthening the wear resistance of clutch tooth surfaces, comprising: mixing iron-nickel-molybdenum alloy powder, nano-tungsten carbide powder, nano-alumina powder, and lubricant; adding a binder and melting and mixing; then adding the mixture into a mold for injection molding; subsequently performing solvent degreasing and thermal degreasing treatments; followed by pre-sintering treatment; then transferring the pre-sintered part into a chemical vapor deposition reaction chamber, where an intermetallic compound transition layer, a titanium carbide main layer, and a nanocrystalline surface layer are sequentially deposited on the tooth surface; then performing vacuum sintering, liquid phase sintering, and pressurized cooling; finally, subjecting the sintered part to hot isostatic pressing (HIP) strengthening treatment; and finally, grinding the tooth surface. This invention can simultaneously address the three aspects of clutch tooth surface strengthening processes: geometric accuracy, wear resistance, and process efficiency.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy component surface strengthening technology, specifically to a method for strengthening the wear resistance of clutch tooth surfaces. Background Technology

[0002] As a core component of mechanical power transmission, the clutch's tooth surface directly bears torque transmission and impact loads. For example, in high-precision systems such as automatic transmissions, the tooth surface must simultaneously meet the following requirements: micron-level meshing accuracy to ensure smooth shifting, and ultra-high wear resistance to withstand 10... 7 More than one cycle of shear stress. However, a long-standing problem in this field is that 80% of clutch failures are due to loss of precision caused by tooth surface wear, which is particularly prominent in heavy vehicles and high-speed machine tools.

[0003] While traditional powder injection molding can efficiently manufacture complex tooth shapes, its strengthening methods have inherent flaws in protecting the tooth surface: the thermal spray coating has a coverage rate of less than 50% at the root transition fillet, and the melt-infiltrated reinforcement layer suffers from a gradient imbalance of "tooth tip enrichment - tooth root depletion" due to the migration of hard particles. Moreover, both subsequent coatings and pre-formulated reinforcing phases can create potential thermal stress hazards between the ceramic layer and the metal matrix, leading to microcracks under sudden temperature changes. These cracks initially cause abnormal meshing noises and eventually evolve into the fracture of the entire tooth.

[0004] In existing technologies, laser cladding technology can be used to improve coating coverage to a certain extent, but the high-temperature heat-affected zone causes a significant decrease in tooth surface hardness, and the repeated thermal cycling scheme is limited by the solid-phase diffusion rate, requiring a large amount of time to form the reinforcement layer.

[0005] Therefore, there is a need in the art for a method to enhance the wear resistance of clutch tooth surfaces to solve the above problems. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, namely the difficulty in balancing geometric accuracy, wear resistance and process efficiency in the existing clutch tooth surface strengthening process.

[0007] This invention provides a method for enhancing the wear resistance of clutch tooth surfaces, the method comprising:

[0008] S1: Mix iron-nickel-molybdenum alloy powder, nano tungsten carbide powder, nano alumina powder and lubricant, add binder and melt-mix;

[0009] S2: Add the melt-mixed feedstock into the mold for injection molding;

[0010] S3: The injection-molded preform is subjected to solvent degreasing and thermal degreasing treatment in sequence;

[0011] S4: The degreased parts are pre-sintered under an argon atmosphere;

[0012] S5: The pre-sintered part after pre-sintering treatment is moved into the chemical vapor deposition reaction chamber, and an intermetallic compound transition layer, a titanium carbide main layer and a nanocrystalline surface layer are sequentially deposited on the tooth surface of the pre-sintered part.

[0013] S6: The deposited part after chemical vapor deposition is sequentially subjected to vacuum sintering, liquid phase sintering and pressurized cooling;

[0014] S7: The sintered part is then subjected to hot isostatic pressing (HIP) strengthening treatment.

[0015] S8: The hot isostatic pressing parts after hot isostatic pressing strengthening treatment are subjected to tooth surface grinding.

[0016] In some preferred embodiments, in step S1, the content of iron-nickel-molybdenum alloy powder is 87-89 wt%, the content of nano-tungsten carbide powder is 5.5-6.5 wt%, the content of nano-alumina powder is 2.8-3.2 wt%, and the lubricant is zinc stearate, with a content of 2.8-3.2 wt%.

[0017] In some preferred embodiments, in step S1, the composition ratio of the iron-nickel-molybdenum alloy powder is: Ni 1.8-2.2wt%, Mo 0.4-0.6wt%, C≤0.03%, and the balance is Fe.

[0018] In some preferred embodiments, in step S1, the composition ratio of the adhesive is: paraffin 63-67 wt%, polypropylene 29-31 wt%, and stearic acid 4.5-5.5 wt%.

[0019] In some preferred embodiments, in step S1, the melt mixing is carried out in a twin-screw mixer under the following conditions: temperature 152-158°C, rotation speed 55-65 rpm, and vacuum degree (0.5-5)×10⁻⁶. 2 Pa.

[0020] In some preferred embodiments, in step S3, the solvent degreasing treatment is performed by treating with n-heptane at 38-42°C for 5.5-6.5 hours, and the thermal degreasing treatment is performed by raising the temperature to 445-455°C at a rate of 1.8-2.2°C / min in a mixed atmosphere of nitrogen and hydrogen, and then holding the temperature for 1.8-2.2 hours, wherein the ratio of nitrogen to hydrogen is 94 / 6-96 / 4.

[0021] In some preferred embodiments, in step S4, the pre-sintering conditions are: a high-purity argon atmosphere, a heating rate of 4.5-5.5℃ / min to 795-805℃ and then holding at that temperature for 28-32 minutes, to obtain a matrix with an open porosity of 19-21% and a connectivity >90%.

[0022] In some preferred embodiments, in step S5, the deposition process of the intermetallic compound transition layer is as follows: at 845-855°C, the volume ratio of TiCl4 introduced is increased from 0.9-1.1 vol% to 2.4-2.6 vol%, the volume ratio of H2 is decreased from 68-72 vol% to 58-62 vol%, and the balance is N2, for 28-32 minutes;

[0023] The deposition process of the titanium carbide main layer is as follows: at 895-905℃, the volume ratio of TiCl4 is kept constant at 2.4-2.6 vol%, the volume ratio of CH4 increases from 1.4-1.6 vol% to 2.9-3.1 vol%, the volume ratio of H2 decreases from 58-62 vol% to 48-52 vol%, and the balance is N2, for 85-95 minutes;

[0024] The deposition process of the nanocrystalline surface layer is as follows: at 875-885℃, the volume ratio of TiCl4 is kept constant at 0.9-1.1 vol%, the volume ratio of CH4 is kept constant at 2.9-3.1 vol%, the volume ratio of H2 is kept constant at 48-52 vol%, and the balance is N2, for 28-32 minutes.

[0025] In some preferred embodiments, in step S6, the vacuum sintering conditions are: a vacuum degree of (0.5-5)×10 2 The temperature is increased to 1275-1285℃ at 9-11℃ / min under Pa;

[0026] The conditions for liquid phase sintering are: holding at 1275-1285℃ in an atmosphere of argon and hydrogen for 55-65 minutes;

[0027] The conditions for pressurized cooling are: cooling to 890-910℃ at a nitrogen pressure of 1.9-2.1MPa and a rate of 38-42℃ / min.

[0028] In some preferred embodiments, in step S7, the hot isostatic pressing conditions are: under an argon atmosphere, a pressure of 14.5-15.5 MPa, a temperature of 1145-1155 °C, and a holding time of 85-95 minutes.

[0029] The method for enhancing the wear resistance of clutch tooth surfaces according to the present invention has the following beneficial effects:

[0030] This invention successfully constructs a TiFe2, TiC, and nano-TiC gradient composite reinforcement layer on the clutch tooth surface. Through the three-dimensional gas channels formed by the open pores in the pre-sintering stage, TiCl4 and CH4 reactive gases permeate into the traditional process blind spots such as the tooth root R angle, achieving a tooth surface reinforcement layer coverage of ≥98.5%. The thickness difference between the tooth tip and tooth root coating is significantly reduced. The TiFe2 intermetallic compound transition layer coordinates the contradiction of thermal expansion mismatch, reduces interfacial thermal stress, and improves bonding strength, achieving no peeling after thousands of thermal shock cycles. CVD deposition and matrix densification are completed simultaneously in a single thermal cycle, significantly reducing energy consumption and shortening the production cycle compared to existing step-by-step processes. At the same time, it ensures that the matrix performance does not degrade, improves bending strength and tooth hardness, and completely avoids the defect of matrix density reduction caused by melt infiltration process. Thus, it simultaneously addresses the geometric accuracy, wear resistance, and process efficiency of clutch tooth surface reinforcement process. Attached Figure Description

[0031] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0032] Figure 1 This is a flowchart of the method for enhancing the wear resistance of clutch tooth surfaces according to the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Based on the background art, it is difficult for existing clutch tooth surface strengthening processes to simultaneously address the issues of geometric accuracy, wear resistance, and process efficiency. This invention provides a method for strengthening the wear resistance of clutch tooth surfaces, aiming to simultaneously address the three aspects of geometric accuracy, wear resistance, and process efficiency in clutch tooth surface strengthening processes.

[0035] The method for enhancing the wear resistance of clutch tooth surfaces according to the present invention includes:

[0036] S1: Mix iron-nickel-molybdenum alloy powder, nano tungsten carbide powder, nano alumina powder and lubricant, add binder and melt-mix;

[0037] In the above, the iron-nickel-molybdenum alloy powder is preferably a water-atomized powder, which serves as the matrix framework. Nickel and molybdenum improve hardenability. The average particle size of the nano-tungsten carbide powder is preferably 75-85 nm, and the average particle size of the nano-alumina powder is preferably 95-105 nm. The nano-tungsten carbide powder not only strengthens the matrix, but its carbide properties also form a lattice match with the TiC coating. The nano-alumina powder acts as a sintering inhibitor, maintaining the porous structure. Preferably, the binder composition ratio is: paraffin wax 63-67 wt%, polypropylene 29-31 wt%, and stearic acid 4.5-5.5 wt%. More preferably, it is paraffin wax 65 wt%, polypropylene 30 wt%, and stearic acid 5 wt%.

[0038] In some preferred embodiments, in step S1 above, the content of iron-nickel-molybdenum alloy powder is 87-89 wt%, the content of nano-tungsten carbide powder is 5.5-6.5 wt%, the content of nano-alumina powder is 2.8-3.2 wt%, the lubricant is zinc stearate, and the content of zinc stearate is 2.8-3.2 wt%. Melt mixing is carried out in a twin-screw mixer under the following conditions: temperature 152-158℃, rotation speed 55-65 rpm, and vacuum degree (0.5-5)×10⁻⁶. 2 Pa.

[0039] S2: Add the melt-mixed feedstock into the mold for injection molding;

[0040] Preferably, in step S2 above, the mold temperature is 68-72℃, the injection pressure is 87-93MPa, the holding pressure is 58-62MPa, and the cooling rate is 28-32℃ / s.

[0041] S3: The injection-molded preform is subjected to solvent degreasing and thermal degreasing treatment in sequence;

[0042] Preferably, in step S3 above, the solvent degreasing treatment is performed by treating with n-heptane at 38-42°C for 5.5-6.5 hours, and the thermal degreasing treatment is performed by raising the temperature to 445-455°C at 1.8-2.2°C / min in a mixed atmosphere of nitrogen and hydrogen and then holding it at that temperature for 1.8-2.2 hours, wherein the ratio of nitrogen to hydrogen is 94 / 6-96 / 4.

[0043] S4: The degreased parts are pre-sintered under an argon atmosphere;

[0044] Preferably, in step S4 above, the pre-sintering conditions are: a high-purity argon atmosphere, a heating rate of 4.5-5.5℃ / min to 795-805℃ and then holding at that temperature for 28-32 minutes, to obtain a matrix with an open porosity of 19-21% and a connectivity >90%.

[0045] S5: The pre-sintered part after pre-sintering treatment is moved into the chemical vapor deposition reaction chamber, and an intermetallic compound transition layer, a titanium carbide main layer and a nanocrystalline surface layer are sequentially deposited on the tooth surface of the pre-sintered part.

[0046] Preferably, in step S5 above, the deposition process of the intermetallic compound transition layer is as follows: at 845-855°C, the volume ratio of TiCl4 increases from 0.9-1.1 vol% to 2.4-2.6 vol%, the volume ratio of H2 decreases from 68-72 vol% to 58-62 vol%, and the remainder is N2, for 28-32 minutes; the deposition process of the titanium carbide main layer is as follows: at 895-905°C, the volume ratio of TiCl4 is kept constant at 2.4-2.6 vol%, and the volume ratio of CH4 decreases from 1... The volume percentage of TiCl4 was increased from 0.4-1.6 vol% to 2.9-3.1 vol%, the volume percentage of H2 decreased from 58-62 vol% to 48-52 vol%, and the balance was N2, for 85-95 minutes; the deposition process of the nanocrystalline surface layer was as follows: at 875-885℃, the volume percentage of TiCl4 was kept constant at 0.9-1.1 vol%, the volume percentage of CH4 was kept constant at 2.9-3.1 vol%, the volume percentage of H2 was kept constant at 48-52 vol%, and the balance was N2, for 28-32 minutes.

[0047] S6: The deposited part after chemical vapor deposition is sequentially subjected to vacuum sintering, liquid phase sintering and pressurized cooling;

[0048] Preferably, in step S6 above, the vacuum sintering conditions are: a vacuum degree of (0.5-5)×10 2 The temperature is increased to 1275-1285℃ at 9-11℃ / min under Pa; the liquid phase sintering conditions are: holding at 1275-1285℃ in an atmosphere of argon and hydrogen for 55-65 minutes; the pressurized cooling conditions are: cooling to 890-910℃ at a nitrogen pressure of 1.9-2.1MPa and a rate of 38-42℃ / min.

[0049] S7: The sintered part is then subjected to hot isostatic pressing (HIP) strengthening treatment.

[0050] Preferably, in step S7 above, the hot isostatic pressing conditions are: under an argon atmosphere, a pressure of 14.5-15.5 MPa, a temperature of 1145-1155 °C, and a holding time of 85-95 minutes.

[0051] S8: Perform tooth surface grinding on the hot isostatic pressing (HIP) strengthened parts.

[0052] Preferably, in step S8 above, the diamond grinding wheel grit size is #790-#810, the feed rate is 0.0045-0.0055 mm / pass, and the surface roughness is Ra0.18-0.22 μm.

[0053] The technical solution of the present invention will be further illustrated below with reference to several embodiments and comparative examples.

[0054] Example 1

[0055] Take 89 wt% of an iron-based alloy powder containing 2.20 wt% nickel, 0.60 wt% molybdenum, and 0.03 wt% carbon, mix it with 6.5 wt% 90 nm tungsten carbide powder, 3.2 wt% 110 nm alumina powder, and 2.8 wt% zinc stearate, add 67 wt% paraffin wax, 29 wt% polypropylene, and 4.5 wt% stearic acid binder, and vacuum knead at 158°C and 65 rpm for 125 minutes (vacuum degree 5 × 10⁻⁶). 2 Pa); In the injection molding stage, the mold temperature was 72℃, the injection pressure was 93MPa, the holding pressure was 62MPa, and the cooling rate was 32℃ / s; Solvent degreasing was performed by soaking in n-heptane at 42℃ for 6.5 hours; Hot degreasing was carried out in an atmosphere of N2:H2 = 94:6, with the temperature increased to 455℃ at 2.2℃ / min and held for 2.2 hours; Pre-sintering was carried out in a high-purity argon atmosphere at 805℃ at 5.5℃ / min and held for 32 minutes, achieving a porosity of 21%; CVD deposition was performed in three steps: T at 855℃... A transition layer was formed by balancing iCl4 (1.1 to 2.6 vol%), H2 (72 to 62 vol%), and N2 for 32 minutes; a main layer was deposited by introducing TiCl4 (2.6 vol%), CH4 (1.6 to 3.1 vol%), and H2 (62 to 52 vol%) at 905°C for 95 minutes; surface nano-sizing was completed by introducing TiCl4 (1.1 vol%) and CH4 (3.1 vol%) at 885°C for 32 minutes; and finally, sintering was carried out at 5 × 10⁻⁶ ℃. 2 The temperature was increased to 1285℃ under vacuum at 11℃ / min and held at 1285℃ with Ar-3.2%H2 for 65 minutes. During the pressurization and cooling stage, 2.1MPa nitrogen gas was introduced and the temperature was rapidly cooled to 910℃ at 42℃ / min. The hot isostatic pressing parameters were 15.5MPa argon gas and 1155℃ for 95 minutes. The tooth surface finishing was performed using an #810 diamond grinding wheel with a feed rate of 0.0045mm / pass.

[0056] Example 2

[0057] Take 89 wt% of an iron-based alloy powder containing 2.20 wt% nickel, 0.60 wt% molybdenum, and 0.03 wt% carbon, mix it with 6.5 wt% 90 nm tungsten carbide powder, 3.2 wt% 110 nm alumina powder, and 2.8 wt% zinc stearate, add 67 wt% paraffin wax, 29 wt% polypropylene, and 4.5 wt% stearic acid binder, and vacuum knead at 158°C and 65 rpm for 125 minutes (vacuum degree 5 × 10⁻⁶). 2Pa); In the injection molding stage, the mold temperature was 72℃, the injection pressure was 93MPa, the holding pressure was 62MPa, and the cooling rate was 32℃ / s; Solvent degreasing was performed by soaking in n-heptane at 42℃ for 6.5 hours; Hot degreasing was carried out in an atmosphere of N2:H2 = 94:6, with the temperature increased to 455℃ at 2.2℃ / min and held for 2.2 hours; Pre-sintering was carried out in a high-purity argon atmosphere at 805℃ at 5.5℃ / min and held for 32 minutes, achieving a porosity of 21%; CVD deposition was performed in three steps: T at 855℃... A transition layer was formed by balancing iCl4 (1.1 to 2.6 vol%), H2 (72 to 62 vol%), and N2 for 32 minutes; a main layer was deposited by introducing TiCl4 (2.6 vol%), CH4 (1.6 to 3.1 vol%), and H2 (62 to 52 vol%) at 905°C for 95 minutes; surface nano-sizing was completed by introducing TiCl4 (1.1 vol%) and CH4 (3.1 vol%) at 885°C for 32 minutes; and finally, sintering was carried out at 5 × 10⁻⁶ ℃. 2 The temperature was increased to 1285℃ under vacuum at 11℃ / min and held at 1285℃ with Ar-3.2%H2 for 65 minutes. During the pressurization and cooling stage, 2.1MPa nitrogen gas was introduced and the temperature was rapidly cooled to 910℃ at 42℃ / min. The hot isostatic pressing parameters were 15.5MPa argon gas and 1155℃ for 95 minutes. The tooth surface finishing was performed using an #810 diamond grinding wheel with a feed rate of 0.0045mm / pass.

[0058] Example 3

[0059] The matrix was based on a nickel 1.85wt% / molybdenum 0.45wt% alloy powder, with 5.5wt% 80nm tungsten carbide and 3.2wt% 100nm alumina added. The mixing and forming parameters were the same as in Example 1. Pre-sintering was carried out at 798℃ in argon atmosphere for 30 minutes to control the porosity to 19.5%. CVD gradient deposition was performed: TiCl3 concentration of 1.1 to 2.4 vol% and H2 concentration of 70 to 60 vol% were deposited at 850℃ for 30 minutes; TiCl4 concentration of 2.5 vol% and CH4 concentration of 1.4 to 2.9 vol% were fixed at 900℃ for 90 minutes; and TiCl4 concentration of 1.0 vol% and CH4 concentration of 3.0 vol% were treated at 880℃ for 30 minutes. Finally, sintering was carried out at 5×10⁻⁶ ℃. 2 The temperature was raised to 1280℃ in a vacuum environment and held in Ar-3.0%H2 for 60 minutes; pressurized cooling was carried out in a nitrogen environment at 2MPa; hot isostatic pressing was performed at 14.5MPa / 1155℃ for 90 minutes; and tooth surface grinding was completed with an #800 grit grinding wheel and a feed rate of 0.0050mm / cycle.

[0060] Example 4

[0061] The substrate was made of nickel 2.15wt% / molybdenum 0.55wt% alloy powder, with 6.5wt% 85nm tungsten carbide and 2.8wt% 95nm alumina added. During the pre-sintering stage, the temperature was raised to 802℃ and held for 30 minutes to control the porosity to 20.5%. In the CVD deposition, the transition layer was deposited at 848℃ with a TiCl4 concentration of 0.9 to 2.6 vol% and an H2 concentration of 69 to 61 vol% for 30 minutes. The main layer was deposited at 898℃ with a TiCl4 concentration of 2.4 vol% and a CH4 concentration of 1.6 to 3.1 vol% for 90 minutes. The subsequent final sintering, pressurized cooling, hot isostatic pressing and grinding processes were the same as in Example 3.

[0062] Example 5

[0063] The feed composition was the same as in Example 2; pre-sintering was carried out at 800°C in argon for 30 minutes, and the porosity stabilized at 20%; CVD gradient deposition used the exact same parameters as in Example 2; the vacuum degree was adjusted to 2×10⁻⁶ during the final sintering stage. 2 Pa, 1280℃, Ar-3.0% H2, held for 60 minutes; pressurized cooling in 2MPa nitrogen at a rate of 42℃ / min to 900℃; hot isostatic pressing at 15MPa / 1150℃ for 90 minutes; tooth surface grinding was performed using a #790 mesh grinding wheel with a feed rate of 0.0055mm / cycle.

[0064] Comparative Example 1

[0065] The substrate feeding and pre-sintering parameters were the same as in Example 2. After obtaining a substrate with a porosity of 21%, the gradient CVD design was cancelled in violation of regulations: a single layer was directly deposited at 900°C for 120 minutes, with the reaction gas being TiCl4 2.5 vol% + CH4 4.0 vol% + H2 50 vol%. The subsequent final sintering, pressurized cooling, hot isostatic pressing and grinding processes were consistent with those in Example 2.

[0066] Comparative Example 2

[0067] The feeding process was the same as in Example 2, but the pre-sintering stage was improperly heated to 1100℃ and held for 60 minutes, resulting in a porosity drop below 0.5%. Then, final sintering was performed: the substrate was completely densified by holding at 1285℃ with Ar-3.2% H2 for 65 minutes. CVD deposition was then performed on the dense substrate: the transition layer was TiCl4 (1.1 to 2.6 vol%) / H2 (72 to 62 vol%) at 855℃ for 32 minutes, the main layer was TiCl4 (2.6 vol%) / CH4 (1.6 to 3.1 vol%) at 905℃ for 95 minutes, and the surface layer was TiCl4 (1.1 vol%) / CH4 (3.1 vol%) at 885℃ for 32 minutes. Finally, hot isostatic pressing was performed at 15.5 MPa / 1155℃ for 95 minutes, followed by grinding with an #810 mesh wheel at 0.0045 mm / cycle.

[0068] The tooth surface properties of the clutches prepared in Examples 1-5 and Comparative Examples 1 and 2 were measured, and the data are shown in the table below.

[0069]

[0070] The table above shows that the coating root coverage of Examples 1-5 is >98.5%, the interface strength is >420MPa, and the wear rate is <0.9mg / km. In contrast, Comparative Example 1 exceeded the upper limit of CH4 concentration, resulting in an increase in carbon deposition rate, while the change in process sequence in Comparative Example 2 resulted in a decrease in root coverage.

[0071] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] The various embodiments in this invention are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0073] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present invention as described above, which are not provided in detail for the sake of brevity.

[0074] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0075] One or more embodiments of the present invention are intended to cover all such substitutions, modifications, and variations that fall within the scope of protection of the present invention. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the scope of protection of this disclosure.

Claims

1. A method for enhancing the wear resistance of clutch tooth surfaces, characterized in that, The method includes: S1: Mix iron-nickel-molybdenum alloy powder, nano tungsten carbide powder, nano alumina powder and lubricant, add binder and melt-mix; S2: Add the melt-mixed feedstock into the mold for injection molding; S3: The injection-molded preform is subjected to solvent degreasing and thermal degreasing treatment in sequence; S4: The degreased parts are pre-sintered under an argon atmosphere; In step S4, the pre-sintering conditions are: high-purity argon atmosphere, heating rate of 4.5-5.5℃ / min to 795-805℃ and then holding for 28-32 minutes to obtain a matrix with an open porosity of 19-21% and a connectivity of >90%; S5: The pre-sintered part after pre-sintering treatment is moved into the chemical vapor deposition reaction chamber, and an intermetallic compound transition layer, a titanium carbide main layer and a nanocrystalline surface layer are sequentially deposited on the tooth surface of the pre-sintered part. In step S5, the deposition process of the intermetallic compound transition layer is as follows: at 845-855℃, the volume ratio of TiCl4 introduced is increased from 0.9-1.1 vol% to 2.4-2.6 vol%, the volume ratio of H2 is decreased from 68-72 vol% to 58-62 vol%, and the balance is N2, for 28-32 minutes; The deposition process of the titanium carbide main layer is as follows: at 895-905℃, the volume ratio of TiCl4 is kept constant at 2.4-2.6 vol%, the volume ratio of CH4 increases from 1.4-1.6 vol% to 2.9-3.1 vol%, the volume ratio of H2 decreases from 58-62 vol% to 48-52 vol%, and the balance is N2, for 85-95 minutes; The deposition process of the nanocrystalline surface layer is as follows: at 875-885℃, the volume ratio of TiCl4 is kept constant at 0.9-1.1 vol%, the volume ratio of CH4 is kept constant at 2.9-3.1 vol%, the volume ratio of H2 is kept constant at 48-52 vol%, and the balance is N2, for 28-32 minutes; S6: The deposited part after chemical vapor deposition is sequentially subjected to vacuum sintering, liquid phase sintering and pressurized cooling; S7: The sintered part is then subjected to hot isostatic pressing (HIP) strengthening treatment. S8: The hot isostatic pressing parts after hot isostatic pressing strengthening treatment are subjected to tooth surface grinding.

2. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S1, the content of iron-nickel-molybdenum alloy powder is 87-89 wt%, the content of nano tungsten carbide powder is 5.5-6.5 wt%, the content of nano alumina powder is 2.8-3.2 wt%, and the lubricant is zinc stearate, with a content of 2.8-3.2 wt%.

3. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S1, the composition ratio of the iron-nickel-molybdenum alloy powder is: Ni 1.8-2.2wt%, Mo 0.4-0.6wt%, C≤0.03%, and the balance is Fe.

4. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S1, the composition ratio of the adhesive is: paraffin 63-67 wt%, polypropylene 29-31 wt%, stearic acid 4.5-5.5 wt%.

5. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S1, melt mixing is carried out in a twin-screw mixer under the following conditions: temperature 152-158℃, rotation speed 55-65 rpm, and vacuum degree (0.5-5)×10⁻⁶. 2 Pa.

6. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S3, the solvent degreasing treatment is carried out with n-heptane at 38-42℃ for 5.5-6.5 hours, and the thermal degreasing treatment is carried out by heating to 445-455℃ at 1.8-2.2℃ / min in a mixed atmosphere of nitrogen and hydrogen and then holding at that temperature for 1.8-2.2 hours, wherein the ratio of nitrogen to hydrogen is 94 / 6-96 / 4.

7. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S6, the vacuum sintering conditions are: a vacuum degree of (0.5-5)×10 2 The temperature is increased to 1275-1285℃ at 9-11℃ / min under Pa; The conditions for liquid phase sintering are: holding at 1275-1285℃ in an atmosphere of argon and hydrogen for 55-65 minutes; The conditions for pressurized cooling are: cooling to 890-910℃ at a nitrogen pressure of 1.9-2.1MPa and a rate of 38-42℃ / min.

8. The method for enhancing the wear resistance of clutch tooth surfaces according to claim 1, characterized in that, In step S7, the hot isostatic pressure conditions are: under an argon atmosphere, pressure 14.5-15.5 MPa, temperature 1145-1155℃, and holding time 85-95 minutes.

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