Self-repairing metal ceramic cutting tool material for cast iron processing and preparation method of self-repairing metal ceramic cutting tool material

Abstract

The invention discloses a self-repairing metal ceramic cutter material for cast iron processing and a preparation method thereof, and belongs to the technical field of metal ceramic cutters. The cutter material has multiple functions of autonomously inducing Al, S and Si in cast iron of a machined part to expand towards the surface of a blade, forming a coating layer with self-lubricating and wear-resisting functions on the surface of the blade in situ, realizing dynamic balance of cutter wear and self-repairing, and reducing elements Al, S and Si with damaged comprehensive performance in the cast iron machined part and the like. The cutter material does not contain Ta and Nb, and the production cost can be remarkably reduced. Through adaptive design of raw materials, components and a preparation process and magnetic performance regulation and control, the problems that an existing tool is high in cost, harmful elements of a machined material are difficult to purify, and a metal ceramic tool is short in service life when used for rough machining are solved, and the metal ceramic tool has the advantages of being low in cost, long in service life and optimized in machining performance.

Description

Technical Field

[0001] This invention belongs to the field of metal-ceramic cutting tool technology, specifically relating to the cutting process of a self-healing metal-ceramic cutting tool material for cast iron machining. Background Technology

[0002] Ti(C,N)-based cermets require less of the strategically critical metal titanium dioxide (W), combining the toughness of metallic materials with the high hardness and wear resistance of ceramic materials. They have been successfully applied as cutting tools in the machining field. Their core advantage lies in their excellent high-speed finishing performance, especially in the semi-finishing and finishing processes of steel and cast iron, achieving excellent surface finish and long tool life. However, their relatively high brittleness makes them unsuitable for roughing operations. Gray cast iron is a commonly used structural material in mechanical manufacturing, and its roughing requires high impact resistance and strong abrasion resistance from the cutting tools. Therefore, CVD-coated carbide tools are typically used for roughing cast iron.

[0003] In existing technologies, to improve the wear resistance and service life of Ti(C,N)-based cermet cutting tools, rare metal carbides such as Ta and Nb are typically added to the tool material. While the addition of these rare metal carbides can improve tool performance, it significantly increases tool production costs. Meanwhile, when traditional uncoated carbide tools cut cast iron, the alloy components in the workpiece diffuse to the tool surface, often leading to the formation of built-up edge. Built-up edge causes accelerated tool wear, reduced machining accuracy, and further shortens tool life. Furthermore, existing tool materials cannot effectively reduce the overall performance-impairing elements in the workpiece through their own action, making it difficult to simultaneously improve the performance of the workpiece.

[0004] Therefore, developing a cermet tool material that requires no addition of Ta or Nb, is low in cost, effectively prevents built-up edge formation, achieves self-repair, extends tool life, and improves the properties of the workpiece has become a pressing technical problem in this field. Simultaneously, improving the overall performance of Ti(C,N)-based cermets to better enable rough machining of workpieces is also a pressing technical problem in this field. Summary of the Invention

[0005] The purpose of this invention is to develop a tool material that can replace CVD-coated cemented carbide, reduce the production cost of cutting tools in existing cast iron machining technologies, solve a series of problems that Ti(C,N)-based cermets cannot meet the comprehensive performance requirements of rough machining tools, extend tool life, and improve the overall performance of the machined workpiece.

[0006] To achieve the above objectives, the present invention provides a self-healing cermet tool material for cast iron machining, wherein the tool material is adapted to be machined from cast iron; the tool material is free of Ta and Nb; and has the following compositional characteristics by mass fraction: Ti(C x N 1-x )-15~25%WC-3~5%Mo2C-0.8~1.5%Cr3C2-13~18%(Co-Ni), of which Ti(C) x N 1-x The margin is 0.5 or 0.6, and the Co / Ni mass fraction ratio is 1~2; the coercivity of the tool material is 8.00~12.00kA / m, and the cobalt magnetism is 4.00~6.00%; the cobalt magnetism, i.e., magnetic saturation, is the measurement result obtained according to the existing national standard with the specific saturation magnetization of pure cobalt as the reference value; during the machining of cast iron, the tool material autonomously induces Al, S and Si in the cast iron workpiece to extend to the surface of the cutting tool, forming a coating layer with self-lubricating and wear-resistant functions in situ on the surface of the cutting tool, realizing the dynamic balance between tool wear and self-repair, and at the same time reducing the elements Al, S and Si that impair the comprehensive performance of the cast iron workpiece;

[0007] The control of the magnetic properties of the tool material, namely the coercivity of 8.00~12.00 kA / m and the cobalt magnetism of 4.00~6.00%, is achieved through the following preparation method:

[0008] A: Raw material selection: Ti(C) x N 1-x The Fisher particle size of Mo2C, Cr3C2, and Co raw material powders is no greater than 1.5 μm; the Fisher particle size of carbonyl Ni raw material powder is no greater than 2.5 μm; and the average particle size of WC raw material powder is no greater than 0.3 μm. x N 1-x The selection criteria for total carbon content is that the total carbon content reaches 95% to 98% of its theoretical carbon content. The selection criteria for other various carbides are that they all need to meet the saturated carbon control requirements, that is, the total carbon content of each carbide must reach its theoretical carbon content.

[0009] B: Preparation of wet milling mixture: Alcohol is used as the wet milling medium, and PEG6000 and PEI70000 are used as forming agent and dispersant; PEG refers to polyethylene glycol, and PEI refers to polyethyleneimine, with average molecular weights of 6000 and 70000, respectively.

[0010] C: Removal of forming agents and dispersants and alloy sintering: The removal of forming agents and dispersants and alloy sintering are carried out in a pressure sintering furnace with rapid cooling function; after the forming agents are removed, vacuum sintering is performed; when the temperature rises to 1350~1400℃, high-purity argon gas is introduced to make the pressure in the sintering furnace reach 5~8kPa, and this pressure is maintained until the temperature in the sintering furnace reaches the sintering temperature of 1490~1510℃; after holding at 1490~1510℃ for 15~20 minutes, high-purity argon gas is continued to be introduced to increase the pressure in the sintering furnace to 2.0~5.5MPa; the holding time for pressure sintering at 1490~1510℃ and 2.0~5.5MPa is 50~70 minutes; after the sintering holding is completed, the rapid cooling function of the sintering furnace is activated to cool the furnace temperature to 1200℃ within 1 hour, and then the furnace is cooled to a furnace exit temperature of less than 70℃.

[0011] In step B of the preparation method of the self-healing cermet tool material for cast iron machining of the present invention, the proportions of PEG6000 and PEI70000 in the total mass fraction of the powder are 2.0~2.3% and 0.05~0.1%, respectively.

[0012] The present invention discloses a self-healing cermet tool material for cast iron machining. In step B of its preparation method, a rolling ball mill is used, the mass ratio of cemented carbide grinding balls to the mixture is (4:1) to (5:1), and the wet grinding time is 60 to 72 hours.

[0013] In the preparation method of a self-healing cermet tool material for cast iron machining of the present invention, step B involves a ball mill rotating at 60-65% of the critical speed, where the critical speed is 42.4 × D. 0.5 The unit is revolutions per minute (rpm); here, D is the diameter of the ball mill barrel, in meters.

[0014] In step B of the preparation method of the self-healing cermet tool material for cast iron machining of the present invention, 350-400 ml of alcohol is added per kilogram of mixture.

[0015] Exploratory research has revealed a close correlation between the physical and mechanical properties of Ti(C,N)-based cermets and their magnetic properties. Magnetic properties can serve as an effective non-destructive testing method for quality control of this material.

[0016] The requirements for raw material particle size and total carbon content in this invention are determined based on a database linking the microstructure and physical-mechanical properties of Ti(C,N)-based cermets.

[0017] This invention utilizes PEG6000 and PEI70000 as forming agents and dispersants to achieve efficient dispersion of nano-WC and easily agglomerated carbonyl nickel powder, thereby obtaining a highly homogeneous mixture and laying the foundation for homogenization of the microstructure of Ti(C,N)-based metal ceramics.

[0018] Cast iron is a type of iron-carbon alloy with a carbon content typically between 2.0% and 4.0%. Besides iron and carbon, cast iron contains silicon (usually 1.0% to 3.0%), and usually also manganese (Mn) and sulfur (S) to control the solidification microstructure. Mn is mainly used for desulfurization and neutralization of sulfur (S), while al is usually considered an impurity element. Reducing the content of al, sulfur, silicon, and manganese (Mn) in cast iron after smelting and casting is beneficial for improving its overall performance. WS2 and MoS2 have self-lubricating properties, while AlTiSiN is a typical component of PVD coatings for cemented carbide tools made from hardened steel, nickel-based alloys, and other difficult-to-machine materials. This invention achieves compositional optimization of the hard phase in Ti(C,N)-based cermets without the addition of alloying additives such as Ta and Nb; achieves homogeneous distribution of W in the W-containing solid solution hard phase of Ti(C,N)-based cermets through ultrafine and nano-scale WC addition and adaptive control of the sintering process; effectively suppresses N spillage loss from the Ti(C,N)-based cermet components and stabilizes the homogeneity of the hard phase through partial pressure control of the atmosphere in the sintering furnace; promotes rapid densification of Ti(C,N)-based cermets through pressure sintering; and effectively suppresses surface precipitation of the binder phase and enhances the red hardness of the cutting tool surface through rapid cooling to 1200℃, laying the foundation for the orderly diffusion of alloying components such as Al, S, Si, and Mn from cast iron to the cutting tool surface induced by the Ti and N components. The self-lubricating and wear-resistant functional coating layer forms the basis for tool self-repair; by cooling in the furnace between 1200℃ and 70℃, the internal stress of Ti(C,N)-based cermets can be effectively reduced; through the reduction of internal stress, the homogenization and full densification of the alloy microstructure, and the control of the C / N ratio and Co / Ni ratio, the comprehensive performance of Ti(C,N)-based cermets can meet the requirements of the comprehensive performance of tools for rough machining of cast iron; through the elementalization and homogenization of the hard phase in Ti(C,N)-based cermets, elements such as Al, S, Si, and Mn in cast iron can be effectively induced to diffuse to the surface of the cutting tool during the machining process, forming in situ on the cutting tool surface with self-lubricating functions such as WS2, MoS2 and Mn-containing sulfur oxides, and highly wear-resistant AlTiSiN and Si and Al-containing oxides. By conducting a high-temperature denitrification reaction of the hard phase in Ti(C,N)-based cermets with sufficient nitrogen, the carbon content on the blade surface is effectively maintained, ensuring the stable existence of the high-hardness, high-wear-resistant carbide [(Ti,W)C] hard phase on the blade surface in the later stages of wear.

[0019] During the rough machining of cast iron, the life cycle of the tool material of this invention exhibits a clear four-stage evolution characteristic, namely (1) the stage of rapid tool wear and selective, orderly, and rapid diffusion of cast iron alloy components to the insert surface; (2) the stage of in-situ formation of self-lubricating and wear-resistant coating and self-repair of the insert surface; (3) the stage of coating wear and local self-repair; and (4) the failure stage. In the failure stage, WS2 and MoS2 with self-lubricating function and AlTiSiN with high wear resistance are transformed into composite sulfur oxides and composite oxides. The wear and crack propagation of the coating exceed its self-repairing ability. The continuous accumulation of fatigue leads to the failure of the insert matrix protective layer, which in turn causes chipping and the end of tool life. Attached Figure Description

[0020] Figure 1 These are drawings of cutting blades used in the cutting experiments of the metal ceramic embodiments, comparative examples, and reference objects of the present invention.

[0021] Figure 2 The images are secondary electron micrographs of the back face of the cutting tool after machining 10 workpieces using the cutting tool in Example 1, along with the energy dispersive spectroscopy (EDS) analysis results of the marked micro-regions.

[0022] Figure 3 The image shows the backscattered electron composition of the back face of the cutting edge near the cutting edge after machining 35 workpieces with the cutting tool in Example 1, along with the energy dispersive spectroscopy analysis results of the marked micro-regions. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments, comparative examples and accompanying drawings.

[0024] The experimental materials are as follows: Ti(C) 0.5 N 0.5 ), Ti(C 0.6 N 0.4 The Fisher particle sizes of Mo2C and Cr3C2 raw material powders are 1.4, 1.2, 1.4 and 1.2 μm, respectively, and the total carbon contents are 9.49%, 11.29%, 5.90% and 13.36%, respectively; the Fisher particle sizes of Co and carbonyl Ni raw material powders are 1.2 and 2.3 μm, respectively; the average particle size of WC raw material powder is 0.2 μm, and the total carbon content is 6.13%.

[0025] The material being processed is gray cast iron with the following composition: 2.090% Si, 0.690% Mn, 0.002% Al, 0.084% Cr, 0.023% Cu, 0.017% P, 0.004% Ca, 0.003% Co, 0.049% Ni, 0.016% Ti, 0.015% Mo, 2.96% C, 0.061% S, with the balance being Fe.

[0026] The machine tool used for rough turning of gray cast iron is a KIWA Triple 21. The machining method is dry rough turning of a single workpiece. The cutting parameters are as follows: linear velocity V c = 280 m / min, feed f n = 0.25 mm / rev, depth of cut A p = 1.5~2.5 mm. For each batch of test inserts, 6 inserts were randomly selected for testing. The average life of the inserts was compared by the number of workpieces machined before the insert chipped.

[0027] The reference material is a commercially available α-Al2O3-based CVD-coated cemented carbide cutting tool produced by a well-known domestic enterprise.

[0028] Example 1

[0029] The alloy composition, by mass fraction, is Ti(C) 0.6 N 0.4 )-25%WC-3.3%Mo2C-0.85%Cr3C2-9%Co-5%Ni, Ti(C 0.6 N 0.4 (The remainder is not specified). The preparation process of the wet-milled mixture is as follows: A tilting rolling ball mill is used, with alcohol as the wet grinding medium. PEG6000 and PEI70000 account for 2.0% and 0.1% of the total powder mass fraction, respectively, and are added during mixture batching. The mass ratio of cemented carbide grinding balls to the mixture is 4:1. The wet milling time is 68 hours, and the ball mill speed is 60% of the critical speed. 400 ml of alcohol is added per kilogram of mixture. The shaped mixture is prepared by spray drying granulation process, and the granulated mixture passes through a 120-mesh sieve. Cutting blades are prepared by compression molding process, with a compression molding pressure of 200 MPa. The drawing of the cutting blade for turning experiments is shown below. Figure 1 The removal of forming agents and dispersants, as well as alloy sintering, were carried out in a pressure sintering furnace with rapid cooling capability. The process parameters for removing forming agents and dispersants were: holding at 200℃, 280℃, 380℃, and 450℃ for 1 hour respectively, and removing them in hydrogen. After the forming agents were removed, vacuum sintering was performed; when the temperature reached 1380℃, high-purity argon was introduced to increase the pressure inside the sintering furnace to 7 kPa, and this pressure was maintained until the temperature inside the sintering furnace reached the sintering temperature of 1500℃; after holding at 1500℃ for 20 minutes, high-purity argon was continued to be introduced to increase the pressure inside the sintering furnace to 4.5 MPa; the holding time for sintering at 1500℃ and 4.5 MPa pressure was 60 minutes; after the sintering holding was completed, the rapid cooling function of the sintering furnace was activated, cooling the furnace temperature to 1200℃ within 1 hour, and then cooling with the furnace to an outlet temperature below 70℃. Test results show that the alloy has a coercivity of 10.79 kA / m and a cobalt magnetism of 4.75%.

[0030] Comparative Example 1

[0031] The alloy composition is Ti(C) 0.6 N 0.4 )-25%WC-3%TaC-2%NbC-3.3%Mo2C-0.85%Cr3C2-9%Co-5%Ni, Ti(C 0.6 N 0.4 (The remainder is not specified). The alloy preparation process parameters are the same as in Example 1. Test results show that the coercivity of the alloy is 10.68 kA / m, and the cobalt magnetism is 4.65%.

[0032] Comparative Example 2

[0033] The alloy composition is Ti(C) 0.6 N 0.4 )-25%WC-3.3%Mo2C-0.85%Cr3C2-5%Co-9%Ni, Ti(C 0.6 N 0.4 (The remainder is used, and the alloy preparation process parameters are the same as in Example 1.) Test results show that the coercivity of the alloy is 2.75 kA / m, and the cobalt magnetism is 1.79%.

[0034] Comparative Example 3

[0035] The alloy composition is Ti(C) 0.7 N 0.3 )-25%WC-3.3%Mo2C-0.85%Cr3C2-9%Co-5%Ni, Ti(C 0.7 N 0.3 The remainder is Ti(C), and the alloy preparation process parameters are the same as in Example 1. 0.7 N 0.3 The raw material powder had a Fisher particle size of 1.4 and a total carbon content of 13.90%. Test results showed that the alloy had a coercivity of 13.07 kA / m and a cobalt magnetism of 6.84%.

[0036] Comparative Example 4

[0037] The alloy composition is Ti(C) 0.4 N 0.6 )-25%WC-3.3%Mo2C-0.85%Cr3C2-5%Co-9%Ni, Ti(C 0.4 N 0.6 The remainder is Ti(C), and the alloy preparation process parameters are the same as in Example 1. 0.4 N 0.6 The raw material powders had a Fisher particle size of 1.0 and a total carbon content of 7.87%. Test results showed that the alloy had a coercivity of 1.12 kA / m and a cobalt magnetism of 0.81%.

[0038] Comparative Example 5

[0039] Except for using WC powder with a Fisher particle size of 1.5 μm and PEG6000 accounting for 2.1% of the total powder mass fraction as a forming agent, and without adding PEI70000, the alloy composition and other preparation process parameters are the same as in Example 1. Test results show that the coercivity of the alloy is 7.91 kA / m, and the cobalt magnetism is 6.50%.

[0040] Comparative Example 6

[0041] Except for using PEG4000 as a forming agent at 2.1% of the total powder mass fraction, the alloy composition and other preparation process parameters were the same as in Example 1. Test results showed that the alloy had a coercivity of 11.24 kA / m and a cobalt magnetism of 4.88%.

[0042] Comparative Example 7

[0043] Except that high-purity argon was not introduced when the temperature reached 1380℃ (high-purity argon was only introduced during the sintering holding stage), the alloy composition and other preparation process parameters were the same as in Example 1. Test results showed that the alloy's coercivity was 9.79 kA / m, and its cobalt magnetism was 5.62%.

[0044] Comparative Example 8

[0045] Except for furnace cooling after holding at the sintering temperature, the alloy composition and other preparation process parameters were the same as in Example 1. Test results showed that the alloy had a coercivity of 10.98 kA / m and a cobalt magnetism of 4.21%.

[0046] Example 2

[0047] The alloy composition, by mass fraction, is Ti(C) 0.5 N 0.5 )-15%WC-5%Mo2C-1.5%Cr3C2-12%Co-6%Ni, Ti(C 0.5 N 0.5 (The remainder is not specified). The preparation process of the wet-milled mixture is as follows: A tilting rolling ball mill is used, with alcohol as the wet milling medium. PEG6000 and PEI70000 account for 2.3% and 0.05% of the total powder mass fraction, respectively, and are added during mixture batching. The mass ratio of cemented carbide grinding balls to the mixture is 5:1. The wet milling time is 72 hours, and the ball mill speed is 65% of the critical speed. 350 ml of alcohol is added per kilogram of mixture. The shaped mixture is prepared by spray drying granulation process, and the granulated mixture passes through a 120-mesh sieve. Cutting blades are prepared by compression molding process, with a compression molding pressure of 200 MPa. The drawing of the cutting blades for turning experiments is shown below. Figure 1The removal of forming agents and dispersants, as well as alloy sintering, were carried out in a pressure sintering furnace with rapid cooling capability. The process parameters for removing forming agents and dispersants were as follows: holding at 200℃, 280℃, 380℃, and 450℃ for 1 hour respectively, and removing them in hydrogen. After the forming agents were removed, vacuum sintering was performed; when the temperature reached 1350℃, high-purity argon was introduced to increase the pressure inside the sintering furnace to 8 kPa, and this pressure was maintained until the temperature inside the sintering furnace reached the sintering temperature of 1490℃; after holding at 1490℃ for 15 minutes, high-purity argon was continued to be introduced to increase the pressure inside the sintering furnace to 2.0 MPa; the holding time for sintering at 1490℃ and 2.0 MPa pressure was 70 minutes; after the sintering holding was completed, the rapid cooling function of the sintering furnace was activated, cooling the furnace temperature to 1200℃ within 1 hour, and then cooling with the furnace to an outlet temperature below 70℃. Test results show that the alloy has a coercivity of 11.81 kA / m and a cobalt magnetism of 5.95%.

[0048] Example 3

[0049] The alloy composition, by mass fraction, is Ti(C) 0.6 N 0.4 )-20%WC-3%Mo2C-0.8%Cr3C2-6.5%Co-6.5%Ni, Ti(C 0.6 N 0.4 (The remainder is not specified). The preparation process of the wet-milled mixture is as follows: A tilting rolling ball mill is used, with alcohol as the wet grinding medium. PEG6000 and PEI70000 account for 2.1% and 0.08% of the total powder mass fraction, respectively, and are added during mixture batching. The mass ratio of cemented carbide grinding balls to the mixture is 5:1. The wet milling time is 60 hours, and the ball mill speed is 62% of the critical speed. 380 ml of alcohol is added per kilogram of mixture. The shaped mixture is prepared by spray drying granulation process, and the granulated mixture passes through a 120-mesh sieve. Cutting blades are prepared by compression molding process, with a compression molding pressure of 200 MPa. The drawing of the cutting blade for turning experiments is shown below. Figure 1The removal of forming agents and dispersants, as well as alloy sintering, were carried out in a pressure sintering furnace with rapid cooling. The process parameters for removing forming agents and dispersants were as follows: holding at 200℃, 280℃, 380℃, and 450℃ for 1 hour, respectively, in hydrogen gas. After the forming agents were removed, vacuum sintering was performed; when the temperature reached 1400℃, high-purity argon gas was introduced to increase the pressure inside the sintering furnace to 5 kPa, and this pressure was maintained until the temperature inside the sintering furnace reached the sintering temperature of 1510℃; after holding at 1510℃ for 20 minutes, high-purity argon gas was continued to be introduced to increase the pressure inside the sintering furnace to 5.5 MPa; the holding time for sintering at 1510℃ and 5.5 MPa pressure was 50 minutes; after the sintering holding was completed, the rapid cooling function of the sintering furnace was activated to cool the furnace temperature to 1200℃ within 1 hour, and then the furnace was cooled with the furnace to an outlet temperature of less than 70℃. Test results show that the alloy has a coercivity of 8.27 kA / m and a cobalt magnetism of 4.18%.

[0050] Table 1 shows the comparison results of cutting experiments on the blade samples prepared in the examples and comparative examples, as well as the reference sample, under the same cutting experimental conditions. The production cost of the patented product of this invention is less than half that of the commercially available α-Al2O3-based CVD-coated cemented carbide of the reference object, and the average lifespan has exceeded 90% of that of the commercially available α-Al2O3-based CVD-coated cemented carbide of the reference object, with stable product quality.

[0051] Figure 2 This is a secondary electron microscopy image of the flank face of the cutting tool after machining 10 workpieces using the cutting tool in Example 1, along with the energy dispersive spectroscopy (EDS) analysis results of the identified micro-regions. Figure 2 Mid-energy spectroscopy (MS / MS) analysis revealed that S and Mn, along with trace impurities Al and Ca, rapidly diffused from the gray cast iron workpiece to the cutting edge surface. Si and Fe from the workpiece also diffused to the cutting edge surface, but this diffusion occurred only on the working surface and did not accumulate at the cutting edge, thus preventing the formation of a cutting edge bulge. The peripheral influence region detected by MS / MS was typically around 10 μm. No N, Co, or Ni were detected in this micro-region, but the C content remained as high as 7.69 wt%. It can be inferred that the alloy components in the outer surface of the cutting edge's coating exist in the form of oxides, carbides, sulfides, and sulfur oxides.

[0052] Figure 3 This is a scanning electron microscope (SEM) backscattered electron composition image of the flank face near the cutting edge, taken after machining 35 workpieces with the cutting tool in Example 1, along with the energy dispersive spectroscopy (EDS) analysis results of the identified micro-regions. Figure 3It can be seen that the coating layer on the blade surface is severely worn near the cutting edge, but some residue remains. The microstructure of the blade matrix is ​​clearly discernible after the coating layer wears away, as shown in the marked micro-area. Energy dispersive spectroscopy (EDS) analysis of the marked micro-area reveals the presence of alloy blade matrix components C, N, Ti, W, Mo, Cr, Co, and Ni, as well as Si, S, Mn, Fe, and Al diffused to the blade surface. The O content is lower than [value missing]. Figure 2 The O content is shown in the figure. Based on the thermodynamic parameter of Gibbs free energy of each phase, the results of energy spectrum analysis, and the surface smoothness of the cutting tool, it can be seen that WS2, MoS2 and sulfur oxides with self-lubricating function, as well as wear-resistant AlTiSiN, carbides and composite oxides are formed in situ during the service of the cutting tool.

[0053]

Claims

1. A self-healing cermet material for cast iron machining, characterized in that: The tool material is compatible with cast iron as the workpiece; the tool material does not contain Ta and Nb; and has the following compositional characteristics by mass fraction: Ti (C x N 1-x )-15~25%WC-3~5%Mo2C-0.8~1.5%Cr3C2-13~18%(Co-Ni), of which Ti(C) x N 1-x The allowance is 0.5 or 0.6, and the Co / Ni mass fraction ratio is 1~2; the coercivity of the tool material is 8.00~12.00kA / m, and the cobalt magnetism is 4.00~6.00%; the cobalt magnetism is magnetic saturation; during the machining of cast iron, the tool material autonomously induces Al, S and Si in the cast iron workpiece to extend to the tool surface, forming a coating layer with self-lubricating and wear-resistant functions in situ on the tool surface, realizing the dynamic balance between tool wear and self-repair, and at the same time realizing the reduction of Al, S and Si elements that impair the comprehensive performance of the cast iron workpiece; The control of the magnetic properties of the tool material, namely the coercivity of 8.00~12.00 kA / m and the cobalt magnetism of 4.00~6.00%, is achieved through the following preparation method: A: Raw material selection: Ti(C) x N 1-x The Fisher particle size of Mo2C, Cr3C2, and Co raw material powders is no greater than 1.5 μm; the Fisher particle size of carbonyl Ni raw material powder is no greater than 2.5 μm; and the average particle size of WC raw material powder is no greater than 0.3 μm. x N 1-x The selection criteria for total carbon content is that the total carbon content reaches 95% to 98% of its theoretical carbon content. The selection criteria for other various carbides are that they all need to meet the saturated carbon control requirements, that is, the total carbon content of each carbide must reach its theoretical carbon content. B: Preparation of wet milling mixture: Alcohol is used as the wet milling medium, and PEG6000 and PEI70000 are used as forming agent and dispersant; PEG refers to polyethylene glycol, and PEI refers to polyethyleneimine, with average molecular weights of 6000 and 70000, respectively. C: Removal of forming agents and dispersants and alloy sintering: The removal of forming agents and dispersants and alloy sintering are carried out in a pressure sintering furnace with rapid cooling function; after the forming agents are removed, vacuum sintering is performed; when the temperature rises to 1350~1400℃, high-purity argon gas is introduced to make the pressure inside the sintering furnace reach 5~8kPa, and this pressure is maintained until the temperature inside the sintering furnace reaches the sintering temperature of 1490~1510℃; after holding at 1490~1510℃ for 15~20 minutes, high-purity argon gas is continued to be introduced to increase the pressure inside the sintering furnace to 2.0~5.5MPa; the holding time for sintering at 1490~1510℃ and 2.0~5.5MPa pressure is 50~70 minutes; after the sintering holding is completed, the rapid cooling function of the sintering furnace is activated to cool the temperature inside the furnace to 1200℃ within 1 hour, and then the furnace is cooled to a discharge temperature of less than 70℃.

2. The self-healing cermet tool material for cast iron machining according to claim 1, characterized in that: In step B of the preparation method, the proportions of PEG6000 and PEI70000 in the total mass fraction of the powder are 2.0~2.3% and 0.05~0.1%, respectively.

3. The self-healing cermet cutting tool material for cast iron machining according to claim 1, characterized in that: In step B of the preparation method, a rolling ball mill is used, the mass ratio of cemented carbide grinding balls to the mixture is (4:1)~(5:1), and the wet grinding time is 60~72 hours.

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