Modified high-performance non-magnetic hard alloy and preparation process thereof

Abstract

The application belongs to the field of hard alloy materials, and provides a modified high-performance non-magnetic hard alloy and a preparation process thereof. An amorphous shell layer of Ni-P-B-Cr-Cu is plated on the surface of WC particles by chemical plating, and the binder phase is converted into Ni3P and Ni3B nano phases by two-stage sintering. The composition is WC 85-95 parts, binder phase 12-25 parts, and grain growth inhibitor 0.5-1.4 parts; the nano phase accounts for 35-50% of the volume of the binder phase and 35-50% of the total volume, the grain size is 80-125 nm; the average grain size of WC is 0.6-1.0 μm; the interface P enrichment layer is 8-15 nm thick (coverage rate 85-95%). Through interface engineering and controlled crystallization from amorphous to nanocrystalline, the relative magnetic permeability is 1.001-1.015, the hardness HRA is 90.5-93.0, the strength TRS is 2.2-3.0 GPa, the toughness KWP is 300-450 N / mm, and the magnetic saturation strength is 0.02-0.15 T, solving the decoupling problem of the magnetic and mechanical properties of traditional non-magnetic hard alloys, and being suitable for magnetic sensitive environments such as semiconductor equipment, precision measurement, MRI tooling and oil service logging.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of cemented carbide materials, and provides a modified high-performance non-magnetic cemented carbide and a preparation process thereof. BACKGROUND

[0002] In high-end technical fields such as semiconductor manufacturing, precision measurement, medical imaging and oil service exploration, hard alloy materials are required to have both weak magnetism and high mechanical properties. The precision clamps and positioning components in semiconductor equipment need to remain stable in a strong electromagnetic field environment to avoid loss of processing precision caused by magnetic interference; the tooling components of MRI medical equipment must meet strict non-magnetic requirements to prevent magnetic field distortion from affecting imaging quality; the while-drilling components in oil service logging need extremely low magnetic response in complex magnetic environments of strata, while bearing high stress and impact load; and precision measurement jigs require no magnetic field interference when working near a magnetic sensitive sensor, and have long-term stable dimensional accuracy and wear resistance. These application scenarios require hard alloy materials to have a relative magnetic permeability close to 1 and a low magnetic saturation strength, and at the same time, to maintain high hardness, high strength and good toughness for comprehensive mechanical properties to ensure reliability and service life under complex working conditions. Meeting these performance requirements not only significantly improves the precision and stability of equipment, but also expands the application range of hard alloy in the magnetic sensitive field, and promotes the technological progress of high-end manufacturing, medical and energy exploration industries, so the development of hard alloy materials with weak magnetism and high strength and toughness has important engineering value and broad market prospects.

[0003] To meet the application requirements of magnetic sensitive environment, the existing non-magnetic hard alloy mainly reduces the magnetism by replacing the traditional Co binder phase with Ni or Ni-Cr alloy or adopting the Ni-P chemical plating coating sintering mode, but these technical routes still have significant deficiencies. First, the contradiction between the magnetic properties and the mechanical properties is difficult to decouple. Although increasing the P content can effectively reduce the magnetic response, it is easy to form a brittle phase to cause the strength and toughness to decrease, and reducing the P content cannot achieve the strict weak magnetic index, so that the material is difficult to balance between the magnetic properties and the mechanical properties. Second, the batch stability problem caused by uncontrolled microstructure. The liquid phase amount and wettability of a single binder phase system fluctuate greatly during sintering, which is easy to cause abnormal grain growth, resulting in the dispersion of hardness and toughness, and the existing Ni-P system lacks effective interface regulation means. The P element is unevenly distributed at the macro scale, and it is difficult to accurately control the interface structure and performance. In addition, the unclear process window is also a common problem. A large number of technical schemes only describe the sintering temperature curve generally, lack of quantitative control parameters of amorphous to nanocrystalline phase transition process and measurable characterization basis of interface enrichment layer, resulting in poor process reproducibility. For example, the Chinese patent with publication number CN107557637A discloses a non-magnetic tungsten steel for ornaments and a preparation method thereof, but there are problems of difficult coordination between P content and mechanical properties and insufficient control of microstructure uniformity, which restricts the stable application of the material. SUMMARY

[0004] (1) Technical problem solved

[0005] The purpose of the present application is to provide a modified high-performance non-magnetic hard alloy and a preparation process thereof, which solves the problems of difficult decoupling of magnetic properties and mechanical properties and uncontrollable microstructure of the current non-magnetic hard alloy.

[0006] (2) Technical solution

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solution:

[0008] A modified high-performance non-magnetic hard alloy, by weight fraction, comprising:

[0009] 85-95 parts of tungsten carbide WC;

[0010] 12-25 parts of binder phase components, the binder phase components contain P 9-13 wt%, B 0.3-1.2 wt%, Cr 0.5-2.0 wt%, Cu 2-6 wt%, and the balance of Ni, and the balance of impurities is ≤0.5 wt% based on the mass of the binder phase;

[0011] 0.5-1.4 parts of grain growth inhibitors, the grain growth inhibitors include 0.2-0.6 parts of VC and 0.3-0.8 parts of Cr3C2;

[0012] The Ni3P and Ni3B nano-phases are contained in the binder phase;

[0013] A P-rich layer exists at the interface between the WC and the binder phase;

[0014] The alloy is a non-magnetic cemented carbide, and the relative magnetic permeability μr is 1.001-1.015.

[0015] Further, the total volume fraction of the Ni3P and Ni3B nano-phases relative to the binder phase is 35-50%, and the average grain size is 80-125 nm;

[0016] The average grain size of the WC is 0.6-1.0 μm.

[0017] Further, the average thickness of the P-rich layer is 8-15 nm, and the coverage length ratio is 85-95%.

[0018] Further, the Rockwell hardness HRA of the non-magnetic cemented carbide is 90.5-93.0;

[0019] The transverse rupture strength TRS is 2.2-3.0 GPa;

[0020] The Palmqvist toughness KWP is 300-450 N / mm;

[0021] The magnetic saturation Ms is 0.02-0.15 T.

[0022] As one of the concepts of the present application, the present application adopts the design of a Ni-P-B-Cr-Cu composite binder phase system mainly for synergistic optimization of the weak magnetism and mechanical properties of cemented carbide. By precisely controlling the P and B contents in the binder phase, Ni3P and Ni3B nano-phases are formed in situ during sintering. These nano-phases significantly reduce the magnetic response of the alloy due to their paramagnetic characteristics, and the dispersion of nano-scale precipitates in the binder phase effectively hinders dislocation movement and strengthens the matrix. The enrichment of P elements at the interface between WC and the binder phase forms a nanoscale enrichment layer, which improves the interface wettability and increases the interface bonding strength, so as to form a stronger metallurgical bond between the WC hard phase and the binder phase, thereby maintaining high hardness while improving the bending strength and fracture toughness of the material. The addition of Cr promotes the formation of carbides at the interface and refines the binder phase structure, and the solid solution of Cu improves the ductility of the binder phase, and the synergistic effect of the two further optimizes the toughness of the binder phase. VC and Cr3C2 as grain growth inhibitors inhibit abnormal grain growth by segregating at the WC grain boundaries, ensuring the fine and uniform distribution of WC grains. This multi-element synergistic control of the binder phase system and the fine interface engineering design enable the material to achieve extremely low magnetic permeability while obtaining excellent hardness, strength and toughness matching, breaking through the technical bottleneck of the mutual restriction of magnetic performance and mechanical performance of traditional non-magnetic cemented carbide.

[0023] The application also discloses a preparation method of the modified high-performance non-magnetic hard alloy.

[0024] S1. Powder pretreatment and activation: after mixing WC powder with a D50 of 0.8-1.0 μm and a grain growth inhibitor, the mixture is cleaned and activated to obtain activated mixed powder;

[0025] S2. Chemical plating of amorphous shell layer: the activated mixed powder is subjected to chemical plating in a plating solution containing Ni source, P source, B source, Cr source and Cu source to obtain composite powder coated with a Ni-P-B-Cr-Cu amorphous shell layer on the surface;

[0026] S3. Shaping and debinding: after adding a shaping agent to the composite powder, the mixture is subjected to debinding to obtain a green compact;

[0027] S4. Two-stage sintering: stage 1 is pre-sintering at a temperature of 1100-1180℃ under vacuum or hydrogen atmosphere; stage 2 is densification sintering at a temperature of 1240-1320℃ under argon atmosphere to obtain a sintered body;

[0028] S5. Hot isostatic pressing and tempering: the sintered body is subjected to hot isostatic pressing at a temperature of 1260-1280℃ under argon atmosphere, and then is tempered at a temperature of 720-780℃ to obtain the hard alloy.

[0029] Further, the cleaning and activation treatment of S1 comprises: sequentially cleaning with anhydrous ethanol and deionized water, and then treating in an activation solution containing stannous chloride dihydrate 10-30 mg / L and palladium chloride 1-3 mg / L at room temperature for 5-15 min, and washing with water until the conductivity of the last washing water is lower than 50 μS / cm at 25℃.

[0030] Further, the plating solution of S2 contains nickel sulfate hexahydrate 0.08-0.12 mol / L, sodium hypophosphite monohydrate 0.20-0.35 mol / L, dimethylamine borane 0.003-0.010 mol / L, trisodium citrate dihydrate 0.10-0.20 mol / L, ammonium chloride 0.10-0.20 mol / L, chromium chloride hexahydrate 0.0005-0.003 mol / L and copper sulfate pentahydrate 0.003-0.015 mol / L.

[0031] The plating solution is used after being degassed to make the dissolved oxygen lower than 1 mg / L.

[0032] Further, the shaping agent of S3 is 0.5-1.0 parts of organic shaping agent by weight, and the organic shaping agent is selected from polyvinyl alcohol, polyethylene glycol or a combination thereof; the debinding is performed at a vacuum degree of 1×10 -3-1×10 -2 Pa, at a temperature of 300-500 DEG C for 1-3 h.

[0033] Further, the vacuum degree of S4 section 1 is 1×10 -4 -1×10 -3 Pa or high-purity hydrogen pressure of 5-20 kPa, and the holding time is 0.5-1.5 h; the argon pressure of S4 section 2 is 0.1-0.3 MPa, the dew point is -60 to -40 DEG C, and the holding time is 10-30 min.

[0034] Further, S4 section 2 further comprises applying a 0.5-2 vol% pulse of methane, and the single pulse duration is 30-120 s, and the pulse number is 1-2.

[0035] Further, S2 is carried out at pH 8.4-9.0 and a temperature of 82-88 DEG C for 6-24 min.

[0036] Further, the argon pressure of S5 hot isostatic pressing is 50-80 MPa, and the holding time is 60-90 min; the tempering time is 1-2 h.

[0037] Further, the use of the hard alloy in semiconductor device components, precision measurement jigs, MRI environmental tooling or oil service logging while drilling components.

[0038] The present application adopts a preparation process of chemical plating amorphous shell layer combined with two-stage sintering and hot isostatic pressing tempering, mainly for enhancing the controllability of microstructure of the hard alloy and the stability of performance. The surface of the WC powder is activated by a stannous chloride dihydrate and palladium chloride activation solution to form catalytic active centers on the surface of the particles, providing uniform nucleation sites for subsequent chemical plating. Chemical plating is carried out in a composite plating solution containing nickel sulfate hexahydrate, sodium hypophosphite monohydrate, dimethylamine borane, chromium chloride hexahydrate and copper sulfate pentahydrate. In the catalytic reduction process, the components are deposited to form a Ni-P-B-Cr-Cu amorphous shell layer. The amorphous structure avoids segregation of elements on a macroscopic scale and provides a uniform structure basis for subsequent phase transformation. The degassing treatment of the plating solution reduces the dissolved oxygen to prevent oxidation reaction from interfering with the quality of the plating layer. The addition of trisodium citrate dihydrate and ammonium chloride regulates the stability of the plating solution and the density of the plating layer. The first stage of the two-stage sintering process promotes the controlled transformation of the amorphous shell layer to nanocrystalline phase and achieves preliminary densification under vacuum or hydrogen atmosphere. The second stage of high-temperature sintering under argon protection completes the densification of the WC skeleton and forms an interface P-rich layer. Methane pulse carburizing further regulates the carbon potential to prevent abnormal grain growth. Hot isostatic pressing eliminates residual pores to improve the density, and tempering releases internal stress and optimizes the distribution of nanophase, realizing precise regulation of uniformity and consistency of performance through the synergistic effect of multiple processes.

[0039] (3)Beneficial technical effects

[0040] 1. Achieving synergistic optimization of magnetic and mechanical properties: Through precise design of the Ni-P-B-Cu composite binder phase system, Ni3P and Ni3B nanophases are formed in situ during sintering, which significantly reduces the magnetic response of the alloy by utilizing their paramagnetic properties, making the relative magnetic permeability reach an extremely low level. At the same time, the nanophases are dispersed in the binder phase, effectively hindering dislocation movement and strengthening the matrix, breaking through the technical bottleneck of the mutual restriction between magnetic properties and mechanical properties of traditional non-magnetic hard alloys, and realizing the unity of weak magnetism and high hardness, high strength, and high toughness.

[0041] 2. Building efficient interface strengthening structure: By precisely regulating the enrichment of P element at the interface between WC and binder phase, a nanoscale P enrichment layer is formed, which significantly improves the interface wettability and increases the interface bonding strength, making the WC hard phase and the binder phase form stronger metallurgical bonding, effectively improving the bending strength and fracture toughness of the material, solving the problem of insufficient mechanical properties caused by weak interface bonding of traditional non-magnetic alloys.

[0042] 3. Achieving precise controllable microstructure: Using chemical plating of amorphous shell layer technology, uniform catalytic active centers are formed on the surface of WC particles through stannous chloride dihydrate and palladium chloride activation treatment, combined with a composite plating solution system containing nickel sulfate hexahydrate, sodium hypophosphite monohydrate, dimethylamine borane, chromium chloride hexahydrate, and copper sulfate pentahydrate, uniform coating of Ni-P-B-Cr-Cu amorphous shell layer is achieved, avoiding element segregation at the macro scale, providing a organizational basis for the subsequent uniform precipitation of nanophases, effectively solving the problem of uncontrollable organization and batch fluctuations in traditional methods.

[0043] 4. Establishing controlled phase transformation and densification path: Through two-stage sintering process design, the first stage is pre-sintering in vacuum or hydrogen atmosphere to promote the controlled transformation of amorphous shell layer to nanocrystalline phase, and the second stage is high-temperature sintering in argon atmosphere to complete densification and form the interface P enrichment layer. Combined with methane pulse carburizing to accurately regulate carbon potential, and hot isostatic pressing to eliminate residual pores and tempering treatment to optimize nanophase distribution, a clear process window for the transformation from amorphous to nanocrystalline is established, realizing the repeatability of organizational evolution and the stability of performance.

[0044] 5. Multi-element synergistic regulation of binder phase properties: Cr promotes the formation of interfacial carbides and refines the binder phase structure, Cu improves the ductility of the binder phase, P and B elements form nanophase strengthening matrix, VC and Cr3C2 as grain growth inhibitors are segregated at WC grain boundaries to inhibit abnormal grain growth. The synergistic effect of multiple elements in composition, structure, and interface level realizes the comprehensive optimization of binder phase toughness, strength, and magnetic properties, providing a material basis for high reliability applications in magnetic sensitive environments. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 Effect of P content in the binder phase of the present application on Rockwell hardness and Palmqvist toughness.

[0046] Figure 2 Effect of B content in the binder phase of the present application on Rockwell hardness and Palmqvist toughness.

[0047] Figure 3 Effect of electroless plating temperature of the present application on Rockwell hardness and transverse rupture strength.

[0048] Figure 4 Macro morphology of the non-magnetic cemented carbide prepared in Example 1 of the present application.

[0049] Figure 5 Micro morphology of the non-magnetic cemented carbide prepared in Example 1 of the present application.

[0050] Figure 6 Morphology of the WC and binder phase interface of the non-magnetic cemented carbide prepared in Example 1 of the present application and its line scan spectrum. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application.

[0052] Example 1

[0053] A modified high-performance non-magnetic cemented carbide, by weight fraction, includes tungsten carbide WC 90 parts, binder phase composition 18 parts and grain growth inhibitor 1.0 part. The binder phase composition of the present embodiment contains P 11.0 wt%, B 0.7 wt%, Cr 1.2 wt%, Cu 4.0 wt%, Ni as the balance 82.8 wt%, and impurities as the balance 0.3 wt%, based on the mass of the binder phase. The grain growth inhibitor of the present embodiment includes VC 0.4 parts and Cr3C2 0.6 parts. The binder phase of the present embodiment contains Ni3P and Ni3B nanophases, which account for 42% of the volume fraction of the binder phase, and the average grain size is 95 nm. The WC and binder phase interface of the present embodiment exists a P-rich layer, the average thickness of the P-rich layer is 12 nm, and the coverage length accounts for 90%. The alloy of the present embodiment is a non-magnetic cemented carbide, the relative magnetic permeability μr is 1.008, the total volume fraction of Ni3P and Ni3B nanophases relative to the binder phase is 42%, and the average grain size of WC is 0.8 μm. The non-magnetic cemented carbide of the present embodiment has a Rockwell hardness HRA of 91.8, a transverse rupture strength TRS of 2.6 GPa, a Palmqvist toughness KWP of 375 N / mm, and a magnetic saturation strength Ms of 0.08 T.

[0054] The preparation method of the embodiment comprises the following steps: S1 powder pretreatment and activation, WC powder with a D50 of 0.9 μm is mixed with a grain growth inhibitor, then sequentially cleaned with anhydrous ethanol and deionized water, treated in an activation solution containing stannous chloride dihydrate 20 mg / L and palladium chloride 2 mg / L at room temperature for 10 min, washed with water until the conductivity of the last washing water is less than 50 μS / cm at 25℃, and then activated mixed powder is obtained; S2 chemical plating of amorphous shell layer, the activated mixed powder is chemically plated in a plating solution containing nickel sulfate hexahydrate 0.10 mol / L, sodium hypophosphite monohydrate 0.28 mol / L, dimethylamine borane 0.006 mol / L, trisodium citrate dihydrate 0.15 mol / L, ammonium chloride 0.15 mol / L, chromium chloride hexahydrate 0.0018 mol / L, and copper sulfate pentahydrate 0.009 mol / L at pH 8.7 and a temperature of 85℃ for 15 min, the plating solution is used after degassing treatment to make the dissolved oxygen less than 1 mg / L, and a composite powder coated with a Ni-P-B-Cr-Cu amorphous shell layer on the surface is obtained; S3 forming and debinding, 0.7 parts of organic forming agent polyvinyl alcohol is added to the composite powder by weight fraction, then formed, and then debinded at a vacuum degree of 5×10 -3 Pa for 2 h at a temperature of 400℃, and a green body is obtained; S4 two-stage sintering, stage 1 is pre-sintered at a temperature of 1140℃ for 1.0 h under a vacuum degree of 5×10 -4 Pa in an atmosphere of argon, stage 2 is densification sintered and subjected to 1.2 vol% methane pulse carburization under an argon atmosphere with an argon pressure of 0.2 MPa and a dew point of-50℃ at a temperature of 1280℃ for 20 min, and a sintered body is obtained; S5 hot isostatic pressing and tempering, the sintered body is subjected to hot isostatic pressing under an argon atmosphere with an argon pressure of 65 MPa at a temperature of 1270℃ for 75 min, and then tempered at a temperature of 750℃ for 1.5 h, and a cemented carbide of the embodiment is obtained.

[0055] Technical features of Example 1: This example adopts moderate formulation parameter design, with binder phase content of 18 parts at a moderate level, combined with 42% nanophase volume fraction and 95 nm grain size, to achieve a balance of hardness, strength and toughness. P content of 11% and an interface enrichment layer of 12 nm thickness provide excellent interface bonding strength, and the relative magnetic permeability of 1.008 is in the low magnetic performance interval. The preparation process adopts a moderate route of 85°C medium temperature electroless plating for 15 min, 1140°C pre-sintering and 1280°C densification sintering, combined with 1.2% methane pulse carburizing and 1270°C hot isostatic pressing, to ensure the uniformity of the microstructure and the stability of the process. The comprehensive performance shows HRA 91.8, TRS 2.6 GPa, KWP 375 N / mm, all of which are at a moderate level, and the process reproducibility is excellent.

[0056] This example is suitable for applications in precision measurement jigs and MRI environment tooling, etc. which require size stability, comprehensive mechanical properties and low magnetic properties, especially precision instrument parts, medical equipment non-magnetic components and detection device positioning fixtures, etc. which require long-term service and strict performance consistency. The balanced performance combination can meet the use requirements under various working conditions.

[0057] Example 2

[0058] A modified high-performance non-magnetic hard alloy, by weight fraction, includes tungsten carbide WC 93 parts, binder phase composition 14 parts and grain growth inhibitor 0.8 parts. The binder phase composition of this example contains P 12.5 wt%, B 0.9 wt%, Cr 1.8 wt%, Cu 3.0 wt%, Ni as the balance 81.4 wt%, and impurities as the balance 0.4 wt%, based on the mass of the binder phase. The grain growth inhibitor of this example includes VC 0.3 parts and Cr3C2 0.5 parts. The binder phase of this example contains Ni3P and Ni3B nanophase, accounting for 50% of the binder phase volume fraction, and the average grain size is 80 nm. The WC and binder phase interface of this example has a P enrichment layer, with an average thickness of 14 nm, and the coverage interface length ratio is 93%. The alloy of this example is a non-magnetic hard alloy, with a relative magnetic permeability μr of 1.004 and an average WC grain size of 0.6 μm. The non-magnetic hard alloy of this example has a Rockwell hardness HRA of 92.8, a transverse rupture strength TRS of 2.3 GPa, a Palmqvist toughness KWP of 320 N / mm, and a magnetic saturation strength Ms of 0.03T.

[0059] The preparation method of the embodiment comprises the following steps: S1, powder pretreatment and activation, WC powder with a D50 of 0.8 μm is mixed with a grain growth inhibitor, then sequentially cleaned with anhydrous ethanol and deionized water, treated in an activation solution containing stannous chloride dihydrate 15 mg / L and palladium chloride 1.5 mg / L at room temperature for 8 min, washed with water until the conductivity of the last washing water is less than 50 μS / cm at 25℃, and the activated mixed powder is obtained; S2, chemical plating of amorphous shell layer, the activated mixed powder is chemically plated in a plating solution containing nickel sulfate hexahydrate 0.11 mol / L, sodium hypophosphite monohydrate 0.32 mol / L, dimethylamine borane 0.008 mol / L, trisodium citrate dihydrate 0.18 mol / L, ammonium chloride 0.18 mol / L, chromium chloride hexahydrate 0.0025 mol / L, and copper sulfate pentahydrate 0.006 mol / L at pH 8.5 and a temperature of 83℃ for 10 min, the plating solution is used after degassing treatment to make the dissolved oxygen less than 1 mg / L, and the composite powder coated with a Ni-P-B-Cr-Cu amorphous shell layer on the surface is obtained; S3, forming and debinding, the composite powder is added with 0.6 parts of organic forming agent polyethylene glycol by weight fraction, then formed, and then debound at a vacuum degree of 3×10 -3 Pa at a temperature of 350℃ for 1.5 h, and a green compact is obtained; S4, two-stage sintering, stage 1, pre-sintering at a temperature of 1160℃ for 0.8 h under a high-purity hydrogen atmosphere with a pressure of 10 kPa, stage 2, densification sintering under an argon atmosphere with a pressure of 0.15 MPa and a dew point of-55℃ at a temperature of 1300℃ for 15 min and applying a methane 0.8 vol% pulse carburizing, a single pulse duration of 60 s and a pulse number of 2, and a sintered body is obtained; S5, hot isostatic pressing and tempering, the sintered body is subjected to hot isostatic pressing under an argon atmosphere with a pressure of 70 MPa at a temperature of 1275℃ for 80 min, and then tempered at a temperature of 730℃ for 1.2 h, and a cemented carbide of the embodiment is obtained.

[0060] Technical features of Example 2: This example is designed for high hardness and extremely low magnetic performance, with a high WC content of 93 parts and a lower binder phase of 14 parts, maximizing the hard phase. High P content of 12.5% and B content of 0.9% promote the formation of 50% high volume fraction of nano-strengthening phase, combined with 80 nm ultra-fine grain and 14 nm thick P-rich layer, 93% interface coverage, to build a dense strengthening network. Using 0.8 μm fine-grained WC powder and lower grain growth inhibitor of 0.8 parts, through 1160°C hydrogen pre-sintering and 1300°C high-temperature densification sintering, supplemented by two methane pulse carburizing and 1275°C hot isostatic pressing, a uniform microstructure is obtained. The performance shows ultra-high hardness HRA 92.8 and ultra-low magnetic saturation strength Ms 0.03 T, relative permeability 1.004, sacrificing part of the toughness (KWP 320 N / mm) for extreme hardness and low magnetic performance.

[0061] Suitable application scenarios: This example is particularly suitable for semiconductor device components and MRI environment tools that require extremely strict hardness and non-magnetic applications, such as semiconductor wafer processing tools, precision grinding components, high-precision positioning pins in nuclear magnetic resonance equipment, and non-magnetic clamps in medical imaging equipment. Key components that need to maintain dimensional accuracy and wear resistance in strong electromagnetic field environments, as well as drilling tool assemblies that need to resist strong wear while not interfering with magnetic measurement signals in oil service logging while drilling components.

[0062] Example 3

[0063] A modified high-performance non-magnetic hard alloy, by weight parts, including tungsten carbide WC 86 parts, binder phase composition 23 parts and grain growth inhibitor 0.6 parts. The binder phase composition of this example contains P 9.5 wt%, B 0.4 wt%, Cr 0.6 wt%, Cu 2.5 wt%, Ni as the balance 86.8 wt%, and impurities as the balance 0.2 wt%, based on the mass of the binder phase. The grain growth inhibitor of this example includes VC 0.2 parts and Cr3C2 0.4 parts. The binder phase of this example contains Ni3P and Ni3B nano phases, accounting for 35% of the volume fraction of the binder phase, with an average grain size of 125 nm. The WC and binder phase interface of this example has a P-rich layer with an average thickness of 9 nm, with an interface length coverage of 87%. The alloy of this example is a non-magnetic hard alloy with a relative magnetic permeability μr of 1.012 and an average WC grain size of 1.0 μm. The non-magnetic hard alloy of this example has a Rockwell hardness HRA of 90.6, a transverse rupture strength TRS of 2.9 GPa, a Palmqvist toughness KWP of 430 N / mm, and a magnetic saturation strength Ms of 0.13 T.

[0064] The preparation method of the embodiment comprises the following steps: S1, powder pretreatment and activation, WC powder with a D50 of 1.0 μm is mixed with a grain growth inhibitor, and then sequentially cleaned with anhydrous ethanol and deionized water, and treated in an activation solution containing stannous chloride dihydrate 25 mg / L and palladium chloride 2.5 mg / L at room temperature for 12 min, and washed with water until the conductivity of the last washing water is less than 50 μS / cm at 25℃, to obtain activated mixed powder; S2, chemical plating of amorphous shell layer, the activated mixed powder is chemically plated in a plating solution containing nickel sulfate hexahydrate 0.09 mol / L, sodium hypophosphite monohydrate 0.22 mol / L, dimethylamine borane 0.004 mol / L, trisodium citrate dihydrate 0.12 mol / L, ammonium chloride 0.12 mol / L, chromium chloride hexahydrate 0.0008 mol / L, and copper sulfate pentahydrate 0.005 mol / L at pH 8.9 and a temperature of 87℃ for 20 min, the plating solution is used after degassing treatment to make the dissolved oxygen less than 1 mg / L, to obtain composite powder coated with a Ni-P-B-Cr-Cu amorphous shell layer on the surface; S3, forming and debinding, after adding 0.9 parts by weight of a mixture of organic forming agents polyvinyl alcohol and polyethylene glycol (mass ratio 1:1) to the composite powder, forming, and then debinding at a temperature of 450℃ for 2.5 h under a vacuum degree of 8×10 -3 Pa, a green compact is obtained; S4, two-stage sintering, stage 1, pre-sintering under a vacuum degree of 2×10 -4 Pa at a temperature of 1120℃ for 1.3 h, stage 2, densification sintering under an argon atmosphere with an argon pressure of 0.25 MPa and a dew point of-45℃ at a temperature of 1260℃ for 25 min, and applying a methane 1.8 vol% pulse carburizing with a single pulse duration of 100 s and a pulse number of 1, to obtain a sintered body; S5, hot isostatic pressing and tempering, hot isostatic pressing of the sintered body under an argon atmosphere with an argon pressure of 55 MPa at a temperature of 1265℃ for 70 min, and then tempering at a temperature of 770℃ for 1.8 h, to obtain the cemented carbide of the embodiment.

[0065] Technical features of Example 3: This example takes high toughness as the design goal, uses a lower WC content of 86 parts and a higher binder phase of 23 parts, cooperates with a 1.0 μm thicker WC grain and a minimum amount of grain growth inhibitor of 0.6 parts, and constructs a structure that prioritizes toughness. Lower P (9.5%) and B (0.4%) contents control the volume fraction of nanophase to 35%, enlarge the grain size to 125 nm, and retain more toughness binder phase. A higher Ni content of 86.8% and a lower Cr and Cu addition amount, through 1.3 h of low-temperature presintering at 1120°C, 25 min of moderate temperature densification sintering at 1260°C, 1.8% of a large dose of methane carburizing, and 770°C high-temperature tempering for 1.8 h, fully diffuse, release internal stress, and optimize the structure. The performance shows excellent toughness KWP 430 N / mm and high strength TRS 2.9 GPa, although the hardness is slightly lower (HRA 90.6), but the comprehensive mechanical properties are outstanding, and the magnetic performance indicators meet the non-magnetic requirements.

[0066] Suitable application scenarios: This example is suitable for application in oil service logging while drilling components and precision measurement tools that need to withstand impact load, vibration stress and complex working conditions, such as impact-resistant joints of drilling tools, drilling measurement instrument shells, wear-resistant sleeves for deep well drilling, and detachable positioning pins of precision measurement equipment, etc. It has unique advantages in application occasions that require frequent assembly and disassembly, may be subjected to accidental impact, but still need to maintain dimensional accuracy and low magnetic interference, and is particularly suitable for long-term reliable service in harsh environments such as geological exploration and oil exploitation.

[0067] Example 4

[0068] A modified high-performance non-magnetic hard alloy, by weight fraction, includes tungsten carbide WC 88 parts, binder phase composition 20 parts, and grain growth inhibitor 1.2 parts. The binder phase composition of this example contains P 10.5 wt%, B 0.6 wt%, Cr 1.0 wt%, Cu 5.0 wt%, and Ni as the balance of 82.4 wt%, and impurities as the balance of 0.5 wt%. The grain growth inhibitor of this example includes VC 0.5 parts and Cr3C2 0.7 parts. The binder phase of this example contains Ni3P and Ni3B nanophase, accounting for 38% of the volume fraction of the binder phase, and the average grain size is 112 nm. The WC and binder phase interface of this example has a P-rich layer, and the average thickness of the P-rich layer is 11 nm, and the coverage interface length accounts for 88%. The alloy of this example is a non-magnetic hard alloy, the relative magnetic permeability μr is 1.010, and the average WC grain size is 0.75 μm. The non-magnetic hard alloy of this example has a Rockwell hardness HRA of 91.5, a transverse rupture strength TRS of 2.7 GPa, a Palmqvist toughness KWP of 390 N / mm, and a magnetic saturation strength Ms of 0.10 T.

[0069] The preparation method of the embodiment comprises the following steps: S1 powder pretreatment and activation, WC powder with a D50 of 0.85 μm is mixed with a grain growth inhibitor, then sequentially cleaned with anhydrous ethanol and deionized water, treated in an activation solution containing stannous chloride dihydrate 18 mg / L and palladium chloride 1.8 mg / L at room temperature for 9 min, washed with water until the conductivity of the last washing water is less than 50 μS / cm at 25℃, to obtain activated mixed powder; S2 chemical plating of amorphous shell layer, chemical plating of the activated mixed powder in a plating solution containing nickel sulfate hexahydrate 0.095 mol / L, sodium hypophosphite monohydrate 0.26 mol / L, dimethylamine borane 0.005 mol / L, trisodium citrate dihydrate 0.14 mol / L, ammonium chloride 0.14 mol / L, chromium chloride hexahydrate 0.0012 mol / L, and copper sulfate pentahydrate 0.012 mol / L at pH 8.6 and a temperature of 86℃ for 18 min, the plating solution is used after degassing treatment to make the dissolved oxygen less than 1 mg / L, to obtain composite powder coated with a Ni-P-B-Cr-Cu amorphous shell layer on the surface; S3 forming and debinding, adding 0.8 parts of organic forming agent polyvinyl alcohol by weight fraction to the composite powder, forming after forming, then debinding at a vacuum degree of 6×10 -3 Pa for 2.2 h at a temperature of 420℃, to obtain a green body; S4 two-stage sintering, stage 1 is pre-sintering at a temperature of 1150℃ for 1.1 h under a high-purity hydrogen atmosphere with a pressure of 15 kPa, stage 2 is densification sintering under an argon atmosphere with a pressure of 0.22 MPa and a dew point of-48℃ at a temperature of 1290℃ for 18 min, and applying a methane pulse carburization with a pulse length of 90 s and a pulse number of 2, to obtain a sintered body; S5 hot isostatic pressing and tempering, hot isostatic pressing of the sintered body under an argon atmosphere with a pressure of 60 MPa at a temperature of 1268℃ for 68 min, followed by tempering at a temperature of 760℃ for 1.6 h, to obtain the cemented carbide of the embodiment.

[0070] Technical features: This embodiment takes the optimization of comprehensive performance as the design concept, adopts a balanced formula of 88 parts of WC, 20 parts of binder phase and 1.2 parts of grain growth inhibitor, forms a dual-phase reinforced structure with 38% nanophase volume fraction and 112 nm grain size through moderate P (10.5%) and B (0.6%) content. High Cu content 5.0% improves wettability and interface bonding, combined with 11 nm thick P-rich layer and 88% interface coverage, realizes the synergistic effect of hard phase and binder phase. Selecting 0.85 μm medium WC powder and 0.75 μm average grain size of finished product, through 1150°C hydrogen pre-sintering, 1290°C moderate temperature densification sintering, combined with 1.5% methane twice pulse carburizing and 760°C medium temperature tempering, a uniform and delicate microstructure is obtained. The performance shows overall excellent indicators of HRA 91.5, TRS 2.7 GPa, KWP 390 N / mm, magnetic properties Ms 0.10 T and μr 1.010 at a good level, which is the best balance point of hardness, strength, toughness and low magnetic properties.

[0071] Application scenarios: This embodiment is suitable for multifunctional general parts of semiconductor equipment components, precision measurement jigs, MRI environment tools, such as precision clamps, chip test probe seats, multifunctional positioning components of medical imaging equipment, standard gauge blocks of precision instruments, and composite function components in oil service logging, etc. It performs excellently in complex application scenarios that require high hardness and wear resistance, high strength and bearing capacity, sufficient toughness and impact resistance, and strict low magnetic requirements, and is particularly suitable for key components of high-end equipment in integrated design, multi-working condition service, long service life and high reliability.

[0072] Comparative Example 1

[0073] Basically the same as Example 1, the difference is that the concentration of sodium hypophosphite monohydrate in the plating solution in the S2 chemical plating amorphous shell layer step is 0.15 mol / L, which reduces the P content in the binder phase composition to 7.2 wt%, and increases the Ni content to 86.6 wt%, while the other binder phase components B 0.7 wt%, Cr 1.2 wt%, Cu 4.0 wt%, and impurities 0.3 wt% remain unchanged.

[0074] Comparative Example 2

[0075] Basically the same as Example 1, the difference is that the concentration of dimethylamine borane in the plating solution in the S2 chemical plating amorphous shell layer step is 0.015 mol / L, which increases the B content in the binder phase composition to 1.5 wt%, and reduces the Ni content to 82.0 wt%, while the other binder phase components P 11.0 wt%, Cr 1.2 wt%, Cu 4.0 wt%, and impurities 0.3 wt% remain unchanged.

[0076] Comparative Example 3

[0077] The same as Example 1, except that the concentration of chromium chloride hexahydrate in the plating solution in the S2 step of electroless plating of the amorphous shell layer was 0.005 mol / L, so that the content of Cr in the binder phase composition was increased to 2.8 wt%, and the content of Ni was correspondingly decreased to 82.2 wt%, while the rest of the binder phase composition, P 11.0 wt%, B 0.7 wt%, Cu 4.0 wt%, and impurities 0.3 wt% remained unchanged.

[0078] Comparative Example 4

[0079] The same as Example 1, except that the amount of tungsten carbide WC in the formulation was 82 parts, and the amount of the binder phase composition was correspondingly increased to 27 parts, while the grain growth inhibitor remained unchanged at 1.0 part, and the composition of the binder phase composition, P 11.0 wt%, B 0.7 wt%, Cr 1.2 wt%, Cu 4.0 wt%, Ni 82.8 wt%, and impurities 0.3 wt% remained unchanged.

[0080] Comparative Example 5

[0081] The same as Example 1, except that the total amount of grain growth inhibitor in the formulation was 0.3 parts, of which VC was 0.15 parts and Cr3C2 was 0.15 parts, while the amount of tungsten carbide WC and the binder phase composition remained unchanged at 90 parts and 18 parts, respectively, and the composition of the binder phase composition, P 11.0 wt%, B 0.7 wt%, Cr 1.2 wt%, Cu 4.0 wt%, Ni 82.8 wt%, and impurities 0.3 wt% remained unchanged.

[0082] Comparative Example 6

[0083] The same as Example 1, except that the electroless plating temperature in the S2 step of electroless plating of the amorphous shell layer was 75°C, and the electroless plating time was 30 min, while the pH remained unchanged at 8.7, and the composition of the plating solution, nickel sulfate hexahydrate 0.10 mol / L, sodium hypophosphite monohydrate 0.28 mol / L, dimethylamine borane 0.006 mol / L, trisodium citrate dihydrate 0.15 mol / L, ammonium chloride 0.15 mol / L, chromium chloride hexahydrate 0.0018 mol / L, and copper sulfate pentahydrate 0.009 mol / L remained unchanged.

[0084] Comparative Example 7

[0085] The same as example 1, except that the pH value of the chemical plating in the S2 step of chemical plating of amorphous shell layer is 7.5, the chemical plating temperature is 85℃, the chemical plating time is 15 min, the plating solution composition of nickel sulfate hexahydrate 0.10 mol / L, sodium hypophosphite monohydrate 0.28 mol / L, dimethylamine borane 0.006 mol / L, trisodium citrate dihydrate 0.15 mol / L, ammonium chloride 0.15 mol / L, chromium chloride hexahydrate 0.0018 mol / L, and copper sulfate pentahydrate 0.009 mol / L remain unchanged.

[0086] Comparative example 8

[0087] The same as example 1, except that the pre-sintering temperature of segment 1 in the S4 two-segment sintering step is 1050℃, the holding time is 2.0 h, and the vacuum degree is 5×10 -4 Pa remain unchanged; the densification sintering temperature of segment 2 is 1280℃, the holding time is 20 min, the argon pressure is 0.2 MPa, the dew point is -50℃, and the methane 1.2 vol% pulse carburization parameters remain unchanged.

[0088] Comparative example 9

[0089] The same as example 1, except that the densification sintering temperature of segment 2 in the S4 two-segment sintering step is 1350℃, the holding time is 35 min, the argon pressure is 0.2 MPa, the dew point is -50℃, and the methane 1.2 vol% pulse carburization, single pulse length 75 s, pulse number 1 remain unchanged; the pre-sintering temperature of segment 1 is 1140℃, the holding time is 1.0 h, the vacuum degree is 5×10 -4 Pa remain unchanged.

[0090] Comparative example 10

[0091] The same as example 1, except that the densification sintering of segment 2 in the S4 two-segment sintering step cancels the methane pulse carburization treatment, and the remaining segment 2 sintering temperature is 1280℃, the holding time is 20 min, the argon pressure is 0.2 MPa, the dew point is -50℃ remain unchanged; the pre-sintering temperature of segment 1 is 1140℃, the holding time is 1.0 h, the vacuum degree is 5×10 -4 Pa remain unchanged.

[0092] Comparative example 12

[0093] The same as example 1, except that a conventional powder metallurgy method is used for preparation, specifically: 90 parts of tungsten carbide WC, 16 parts of metal nickel powder (containing 11.0 wt% of phosphorus nickel powder), 0.22 parts of metal chromium powder, 0.72 parts of metal copper powder, 0.13 parts of metal boron powder, 0.4 parts of VC, 0.6 parts of Cr3C2 are mixed by ball milling for 24 h, then 0.7 parts of polyvinyl alcohol is added for forming, and the vacuum degree is 5×10 -3 Pa at 400℃ for 2 h to debind, then vacuum sintering at 1420℃ for 1.5 h in one stage, finally isostatic pressing at 1270℃ for 75 min under argon pressure of 65 MPa, tempering at 750℃ for 1.5 h, to obtain the cemented carbide. In the alloy prepared by this method, the binder phase does not form an amorphous shell structure by electroless plating, and there is no P enrichment layer at the interface between WC and the binder phase. -4 Pa at 400℃ for 2 h to debind, then vacuum sintering at 1420℃ for 1.5 h in one stage, finally isostatic pressing at 1270℃ for 75 min under argon pressure of 65 MPa, tempering at 750℃ for 1.5 h, to obtain the cemented carbide. In the alloy prepared by this method, the binder phase does not form an amorphous shell structure by electroless plating, and there is no P enrichment layer at the interface between WC and the binder phase.

[0094] Performance test:

[0095] Experiment 1: magnetic property test, test object is modified high-performance non-magnetic cemented carbide sintered body (φ10 mm×3 mm, Ra≤0.4 μm), test purpose is to evaluate the applicability of the material in a magnetic sensitive environment. VSM vibrating sample magnetometer is used to collect the magnetic hysteresis loop at room temperature by applying a magnetic field of 0-30 kOe, the relative magnetic permeability μr is measured in the low field region (0-100 Oe, step 10 Oe), and the magnetic saturation Ms is determined by extrapolation in the high field region (20-30 kOe). According to GB / T 3656-2008 and ASTM A977 / A977M-2016, calculate μr=(1+M / H) and Ms=μ0×Msat, 5 samples per group.

[0096] Experiment 2: Rockwell hardness test, test object is polished cemented carbide sample (≥10 mm×10 mm×5 mm, Ra≤0.05 μm), test purpose is to evaluate the material's resistance to plastic deformation and wear resistance potential. HR-150A Rockwell hardness tester is used, diamond cone indenter (120°), initial test force 98.07 N, total test force 588.4 N, hold for 3 s, A scale measurement of 10 points (spacing ≥3 mm). According to GB / T 230.2-2012 and ISO 6508-1:2016, take the average value after removing the extreme value.

[0097] Experiment 3: Transverse Rupture Strength Test, Test object: Standard Three-Point Bending Specimen (6.5 mm x 5.2 mm x 20 mm, Ra≤0.4 μm), Test purpose: To determine the bending rupture resistance of the material. Using an electronic universal testing machine, support span 12.0 mm, loading rate 1.0 mm / min, load to fracture at 23±2℃, record the maximum load Fmax, according to TRS=3FmaxL / (2bh2) calculation, ≥10 samples per group. Technical index: TRS 2.2-3.0 GPa, coefficient of variation ≤8%, measurement uncertainty ≤±5%.

[0098] Experiment 4: Palmqvist Toughness Test, Test object: Mirror Polished Specimen (≥15 mm x 15 mm x 5 mm, Ra≤0.025 μm), Test purpose: To evaluate the crack propagation resistance of the material. Using HV-1000 Vickers Hardness Tester, diamond four-pyramid indenter (136°), load 294.2 N, hold for 15 s, measure the radial crack length of the four corners of the indentation using a metallographic microscope (400x), ≥6 indentations per sample (spacing ≥5 mm). According to ISO 28079:2009 and GB / T 35104-2017, calculate according to KWP=0.0028xHVx(F / ∑L). Technical index: KWP 300-450 N / mm, relative standard deviation ≤10%, measurement uncertainty ≤±8%.

[0099] Experiment 5: Interface P-rich Layer Characterization Test, Test object: WC and binder phase interface region, Test purpose: To verify the effect of interface engineering control. Using FIB to prepare 50-70 nm thick TEM thin sections, using spherical aberration-corrected transmission electron microscopy (200 kV) equipped with EDS, selecting 10-15 interfaces in STEM-HAADF mode, EDS line scanning along the vertical interface direction (30-50 nm long, 0.5 nm step, 3 s per point), EDS area scanning (50 nm x 50 nm, 256 x 256 pixels) for representative interfaces to obtain P, Ni, W element distribution. According to ISO 22309:2011 and GB / T 17359-2012, a continuous area with P concentration more than 20% of the average value of the matrix is defined as a rich layer, the thickness (3 times per interface) and coverage rate (statistical analysis of ≥30 WC grains) are measured.

[0100] Experiment 6: Wear Resistance Test. The test object was a standard wear specimen (φ6 mm × 15 mm, end face Ra ≤ 0.2 μm). The purpose of the test was to evaluate the service durability of the material. A UMT friction and wear testing machine was used. The wear material was a quenched GCr15 steel disc (HRC 60-62). The load was 10 N, the rotation speed was 200 rpm, the wear radius was 10 mm, the time was 60 min (sliding distance 720 m), and the dry friction conditions were 23±2℃. The friction coefficient was recorded in real time. Each group had ≥5 samples. According to GB / T 12444.1-2016, ISO 20808:2016 and ASTM G99-17, the mass change Δm before and after wear was measured using an electronic balance (0.01 mg accuracy). The wear rate Ws = Δm / (ρ × F × L) (mm) was calculated. 3 The wear track morphology and volume were measured using a white light interferometer (N·m), and the wear mechanism was observed using SEM. Typical performance index: Wear rate ≤ 1 × 10⁻⁶. -6 mm 3 / (N·m), friction coefficient 0.3-0.6, measurement uncertainty ≤±10%.

[0101] Figure 1 The effect of P content in the binder phase of this invention on Rockwell hardness and Palmqvist toughness is shown. The overall performance is optimal when the P content is 11.0 wt% (hardness 91.8 HRA, toughness 392 N / mm). Figure 2 The effect of B content in the binder phase on Rockwell hardness and Palmqvist toughness in this invention was investigated. The overall performance was optimal when the B content was 0.7 wt% (hardness 91.8 HRA, toughness 375 N / mm), revealing the critical balance between nanophase strengthening and embrittlement. Figure 3 This invention demonstrates the effect of electroless plating temperature on Rockwell hardness and transverse fracture strength. The peak performance (hardness 91.8 HRA, strength 2.62 GPa) at 85℃ confirms the crucial control role of temperature on coating quality and interface engineering. Combining the three sets of experiments, the optimal values ​​of all key parameters are located in the middle of the control range, fully verifying the scientific nature of the parameter settings and the effectiveness of the synergistic mechanism between interface engineering and nanophase reinforcement, providing precise process control basis for industrial-scale preparation.

[0102] Figure 4 The alloy surface of Example 1 is smooth and flat, with a density of 99.5% and no cracks or pores, proving that the two-stage sintering process achieved sufficient densification. Figure 5 SEM backscattered images showed that WC grains were uniformly distributed, the binder phase formed a continuous network structure, and the nanophase was dispersed with a volume fraction of 42%, verifying the effectiveness of the grain inhibitor and the electroless plating process. Figure 6STEM-HAADF image and EDS line scan directly prove that P enrichment layer exists in WC / binder phase interface, coverage rate is more than 90%, P enrichment layer effectively relieves the difference of thermal expansion coefficient between WC and binder phase(5.2*10 -6 K⁻¹ vs 13*10 -6 K⁻¹) and improves the interface bonding strength by covalent bond, the synergistic effect of interface P enrichment layer engineering and nanophase strengthening realizes the excellent performance of hardness 91.8 HRA, strength 2.6 GPa, toughness 375 N / mm, Figures 4-6 The multi-scale characterization from macroscopic density, microstructure uniformity to interface fine structure fully proves the scientificity and effectiveness of the reasonable matching of the chemical plating amorphous shell layer process, two-stage sintering process and pulse carburizing process, which provides a solid microstructure basis for the reliability and industrial application of the technical scheme.

[0103] The properties of the alloys of the examples and comparative examples are summarized in Table 1, the low sodium phosphate concentration of Comparative Example 1 reduces the P content to 7.2 wt%, the P enrichment layer is only 7 nm, which leads to insufficient interface strengthening, the toughness is reduced to 360 N / mm, and the wear resistance is degraded to 0.78*10 -6 mm 3 / (N*m), the high dimethylamine borane concentration of Comparative Example 2 increases the B content to 1.5 wt%, which leads to excessive precipitation of nanophase, the toughness is only 310 N / mm, and the strength is only 2.2 GPa, the high chromium chloride concentration of Comparative Example 3 increases Cr to 2.8 wt%, which leads to degradation of toughness to 335 N / mm, the low WC content of 82 parts of Comparative Example 4 destroys the continuity of the skeleton, which reduces the hardness to 89.2 HRA, and degrades the wear resistance to 1.08*10 -6 mm 3 / (N*m), the low inhibitor of 0.3 parts of Comparative Example 5 leads to grain coarsening, which reduces the hardness to 89.8 HRA, and the strength is only 2.2 GPa, the low chemical plating temperature of 75℃ of Comparative Example 6 leads to insufficient amorphization of the plating layer, which results in a strength of only 2.3 GPa and a toughness of only 345 N / mm, the low pH value of 7.5 of Comparative Example 7 leads to a decrease in the uniformity of the plating layer, which results in a toughness of only 355 N / mm, the low pre-sintering temperature of 1050℃ of Comparative Example 8 leads to excessive P removal, which results in a hardness of only 90.2 HRA and a strength of only 2.1 GPa, the high sintering temperature of 1350℃ of Comparative Example 9 leads to grain coarsening and nanophase dissolution, which reduces the P enrichment layer to 8 nm and the hardness to 89.5 HRA, Comparative Example 10 cancels pulse carburizing, which leads to carbon imbalance, resulting in a strength of only 2.2 GPa and a toughness of only 340 N / mm, Comparative Example 12 is not subjected to chemical plating, which has no P enrichment layer, resulting in a serious lack of interface bonding force, a hardness of only 88.5 HRA, a strength of only 1.9 GPa, a toughness of only 285 N / mm, and a wear resistance degradation to 1.25*10 -6 mm3 (N·m), hardness decreased by 3.6%, strength decreased by 27%, toughness decreased by 24%, and wear resistance deteriorated by 108% compared with Example 1, and the system comparison shows that the synergistic control of the key parameters such as P content, B content, Cr content, WC content, inhibitor dosage, electroless plating temperature, pH value, pre-sintering parameters, densification sintering parameters, pulse carburizing, etc. is crucial to realize the interface P enrichment layer engineering and the synergistic effect of Ni3P-Ni3B nanophase strengthening, and any single parameter deviating from the optimization window will lead to significant performance degradation. The hardness average of the example group is 91.7 HRA, which is 1.7% higher than the 90.2 HRA of the comparative example group, the strength average is 2.6 GPa, which is 18% higher than the 2.2 GPa of the comparative example group, the toughness average is 369 N / mm, which is 6.6% higher than the 346 N / mm of the comparative example group, and the wear resistance average is 0.61*10 -6 mm 3 / (N·m) is 27% higher than the 0.84*10 -6 mm 3 / (N·m) of the comparative example group, the average thickness of the P enrichment layer is 11.5 nm, which is 18.6% higher than the 9.7 nm of the comparative example group, which fully verifies the rationality, reliability and effectiveness of the technical solution, and proves that the synergistic mechanism of constructing the interface P enrichment layer engineering and precisely regulating the Ni3P-Ni3B nanophase strengthening can realize the comprehensive improvement of hardness, strength, toughness and wear resistance on the premise of maintaining excellent non-magnetic performance.

[0104] Table 1 Performance summary of the alloy of the example and the comparative example

[0105]

[0106] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that any equivalent structural transformation made under the concept of the present application and using the contents of the present application specification and drawings should be covered within the protection scope of the claims of the present application.

Claims

1. A modified high-performance non-magnetic cemented carbide, characterized in that, By weight, including: Tungsten carbide (WC) 85-95 parts; The binder phase comprises 12-25 parts, wherein the binder phase contains, by mass, 9-13 wt% P, 0.3-1.2 wt% B, 0.5-2.0 wt% Cr, 2-6 wt% Cu, with Ni as the balance, and the balance of impurities ≤0.5 wt%. 0.5-1.4 parts of grain growth inhibitor, wherein the grain growth inhibitor comprises 0.2-0.6 parts of VC and 0.3-0.8 parts of Cr3C2; After sintering, the binder phase contains Ni3P and Ni3B nanophases; A P-rich layer exists at the interface between WC and the binder phase; The alloy is a non-magnetic hard alloy with a relative permeability μr of 1.001-1.

015.

2. The modified high-performance non-magnetic cemented carbide as described in claim 1, characterized in that, The total volume fraction of Ni3P and Ni3B nanophases relative to the binder phase is 35-50%, and their average grain size is 80-125 nm. The average grain size of WC is 0.6-1.0 μm.

3. The modified high-performance non-magnetic cemented carbide as described in claim 1, characterized in that, The average thickness of the P-enriched layer is 8-15 nm, and the coverage area accounts for 85-95% of the interface length.

4. The modified high-performance non-magnetic cemented carbide as described in claim 1, characterized in that, The non-magnetic cemented carbide has a Rockwell hardness (HRA) of 90.5-93.

0. The transverse fracture strength (TRS) is 2.2-3.0 GPa; Palmqvist toughness KWP is 300-450 N / mm; The magnetic saturation intensity Ms is 0.02-0.15 T.

5. A method for preparing a modified high-performance non-magnetic cemented carbide as described in any one of claims 1-4, characterized in that, Includes the following steps; S1. Powder pretreatment and activation: WC powder with a D50 of 0.8-1.0 μm is mixed with a grain growth inhibitor, and then washed and activated to obtain activated mixed powder; S2. Chemical plating of amorphous shell: Activated mixed powder is chemically plated in a plating solution containing Ni source, P source, B source, Cr source and Cu source to obtain composite powder with a Ni-PB-Cr-Cu amorphous shell coating on the surface. S3. Forming and Debinding: After adding a forming agent to the composite powder and forming, debinding is performed to obtain a pressed compact; S4. Two-stage sintering: Stage 1 is pre-sintered at a temperature of 1100-1180℃ under vacuum or hydrogen atmosphere; Stage 2 is densified sintered at a temperature of 1240-1320℃ under argon atmosphere to obtain a sintered body. S5. Hot isostatic pressing and tempering: The sintered body is subjected to hot isostatic pressing at a temperature of 1260-1280℃ in an argon atmosphere, followed by tempering at a temperature of 720-780℃ to obtain the cemented carbide.

6. The method for preparing a modified high-performance non-magnetic cemented carbide as described in claim 5, characterized in that, The cleaning and activation treatment of S1 includes: sequentially cleaning with anhydrous ethanol and deionized water, then treating in an activation solution containing 10-30 mg / L stannous chloride dihydrate and 1-3 mg / L palladium chloride at room temperature for 5-15 min, and washing with water until the conductivity of the final wash water at 25°C is less than 50 μS / cm.

7. The method for preparing a modified high-performance non-magnetic cemented carbide as described in claim 5, characterized in that, The S2 plating solution contains 0.08-0.12 mol / L nickel sulfate hexahydrate, 0.20-0.35 mol / L sodium hypophosphite monohydrate, 0.003-0.010 mol / L dimethylamine borane, 0.10-0.20 mol / L trisodium citrate dihydrate, 0.10-0.20 mol / L ammonium chloride, 0.0005-0.003 mol / L chromium chloride hexahydrate, and 0.003-0.015 mol / L copper sulfate pentahydrate. The plating solution is degassed to reduce dissolved oxygen to below 1 mg / L before use.

8. The method for preparing a modified high-performance non-magnetic cemented carbide as described in claim 5, characterized in that, The molding agent of S3 is 0.5-1.0 parts by weight of an organic molding agent, wherein the organic molding agent is selected from polyvinyl alcohol, polyethylene glycol, or a combination thereof; the debinding is performed at a vacuum degree of 1×10 -3 -1×10 -2 Pa is kept at 300-500℃ for 1-3 hours.

9. The method for preparing a modified high-performance non-magnetic cemented carbide as described in claim 5, characterized in that, The vacuum level of segment S4 is 1×10⁻⁶. -4 -1×10 -3 The pressure of Pa or high-purity hydrogen is 5-20 kPa, and the holding time is 0.5-1.5 h; the argon pressure of S4 section 2 is 0.1-0.3 MPa, the dew point is -60 to -40℃, and the holding time is 10-30 min.

10. The method for preparing a modified high-performance non-magnetic cemented carbide as described in claim 5, characterized in that, S4 section 2 also includes applying 0.5-2 vol% methane pulse carburizing, with a single pulse duration of 30-120 s and 1-2 pulses.

Images