Wear-resistant and light-weight hard alloy material, preparation method and application of wear-resistant and light-weight hard alloy material in anti-skid nails

Abstract

The invention relates to the technical field of alloys, in particular to a wear-resistant and light-weight hard alloy material, a preparation method and application of the wear-resistant and light-weight hard alloy material in anti-skid nails. According to the material, interface bonding is enhanced through double-grafted reduced graphene oxide, high-entropy alloy pre-alloyed powder is adopted as a binding phase, hard phases such as tungsten carbide, titanium diboride and titanium carbide are combined, and the composite material is prepared through multiple processes such as composite slurry preparation, spray drying, multi-stage sintering, vacuum impregnation secondary coating and hot-pressing densification. And constructing a gradient structure from inside to outside. The obtained material is low in density, high in hardness, high in transverse breaking strength, excellent in toughness and wear resistance and high in thermal diffusivity, the problems that a traditional anti-skid nail is high in density, weak in interface bonding and poor in thermal conductivity are effectively solved, and light weight and long-acting durability are achieved.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and in particular to a wear-resistant, lightweight cemented carbide material, its preparation method, and its application in anti-slip nails. Background Technology

[0002] Traditional anti-skid studs generally use tungsten-cobalt-based hard alloys. The high density of these studs significantly increases tire rolling resistance, leading to decreased fuel economy and exacerbating potential damage to the tire's frame structure. Simply reducing size to achieve weight reduction inevitably sacrifices the material's wear life, making it difficult to meet the long-term service requirements under complex road conditions.

[0003] Existing technologies attempt to improve performance by introducing other hard phases or adjusting the composition of the binder phase, but the results are often limited. For example, adding titanium carbide alone or adjusting the cobalt content can adjust hardness or toughness to some extent, but the problem of insufficient interfacial bonding between phases is not fundamentally solved. When the material is subjected to a combination of intermittent impact and continuous wear, it is prone to interfacial debonding and early crack propagation, resulting in a decrease in overall reliability.

[0004] Furthermore, some studies have attempted to enhance toughness and wear resistance by introducing nanomaterials such as graphene. However, unmodified graphene exhibits poor dispersion in metal matrices and is prone to agglomeration. This not only hinders the realization of its excellent mechanical properties but may also become stress concentration points, accelerating material failure. Simultaneously, conventional sintering processes struggle to achieve high densification while precisely controlling the gradient structure from the material's interior to its surface. This results in a mismatch between the core and surface properties, making the material susceptible to surface peeling or internal cracking under harsh operating conditions.

[0005] Furthermore, the thermal conductivity of existing cemented carbides is generally unsatisfactory. Under continuous frictional heating conditions, the local temperature rise at the working end softens the binder phase, accelerates the wear process, and may induce thermal stress cracks, seriously affecting the safety and lifespan of anti-slip studs. Therefore, developing a cemented carbide material that can achieve lightweight, high wear resistance, high toughness, and good thermal management performance through multi-level synergistic effects from component design and interface control to structural construction has become a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a wear-resistant, lightweight cemented carbide material, its preparation method, and its application in anti-skid studs, so as to solve the problems of existing cemented carbide anti-skid studs, which have high density, weak interfacial bonding, and poor thermal conductivity, resulting in large additional loads on vehicles, insufficient impact fatigue resistance, and easy thermal softening and accelerated wear under continuous friction.

[0007] To achieve the above objectives, the present invention provides a method for preparing a wear-resistant and lightweight cemented carbide material, comprising the following steps:

[0008] (1) Preparation of double-grafted reduced graphene oxide powder: The graphene oxide dispersion was stirred at 0-5℃, and the first diazotization grafting was carried out with p-aminophenylphosphonic acid and diazotizing agent, and the second diazotization grafting was carried out with p-methylaniline and diazotizing agent. Then, a reducing agent was added for reduction treatment, and the powder was obtained by washing and drying.

[0009] (2) Preparation of high-entropy alloy pre-alloyed powder: aluminum powder, cobalt powder, chromium powder, iron powder, nickel powder and boron powder and silicon powder are subjected to planetary ball milling pre-alloying treatment in an organic solvent, and then dried to obtain high-entropy alloy pre-alloyed powder;

[0010] (3) Preparation of composite slurry: Tungsten carbide powder, titanium diboride powder, titanium carbide powder, high entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder are added to an aqueous dispersion medium, a dispersant and an organic binder are added, and the mixture is wet-milled and sieved to obtain a composite slurry.

[0011] (4) Preparation of primary dense blank: The composite slurry is spray-dried to obtain spherical particles, which are then loaded into a mold and sintered under a protective atmosphere according to a multi-stage heating-holding regime to obtain the primary dense blank;

[0012] (5) Secondary coating: Tungsten carbide powder, titanium diboride powder, titanium carbide powder, high entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder are prepared into a feed slurry. The initial dense blank is placed in the feed slurry for vacuum impregnation. The impregnated blank is then dip-coated, scraped and dried to obtain a secondary coated blank.

[0013] (6) Hot pressing densification: The secondary coated blank is placed in a vacuum hot press furnace for hot pressing sintering, cooled and demolded to obtain wear-resistant and lightweight cemented carbide material.

[0014] Preferably, the graphene oxide in step (1) consists of 1-5 layers with an average sheet diameter of about 1.5 μm.

[0015] Preferably, step (1) involves two diazotizations at 0-5°C using a hydrochloric acid / sodium nitrite system, followed by reduction with 25wt% hydrazine monohydrate in a 95°C water bath for 45 min, and vacuum drying at 60°C for 12 h.

[0016] Preferably, in step (1), the mass ratio of graphene oxide, p-aminophenylphosphonic acid and p-methylaniline is 1.8:3-5:2.5-3.5.

[0017] Preferably, in step (2), the mass ratio of aluminum powder, cobalt powder, chromium powder, iron powder, nickel powder, boron powder and silicon powder is 107:233:206:221:232:3-5:4-8.

[0018] Preferably, in step (2), the average particle size of aluminum powder is 2.4 μm, the average particle size of cobalt powder is 1.6 μm, the average particle size of chromium powder is 1.4 μm, the average particle size of iron powder is 5.7 μm, the average particle size of nickel powder is 2.6 μm, the average particle size of boron powder is 0.8 μm, and the average particle size of silicon powder is 0.5 μm.

[0019] Preferably, in step (2), the ball milling uses ethanol as the medium, a ball-to-material ratio of 10:1, a rotation speed of 300 rpm, and a time of 14-18 h.

[0020] Preferably, in step (3), the mass ratio of tungsten carbide powder, titanium diboride powder, titanium carbide powder, high-entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder is 580-620:100-150:60-100:40-80:3-5:3-5:1-2.

[0021] Preferably, in step (3), the average particle size of tungsten carbide powder is 0.8 μm, the average particle size of titanium diboride powder is 3 μm, the average particle size of titanium carbide powder is 2 μm, the average particle size of vanadium carbide powder is 2 μm, and the average particle size of chromium tricarbide powder is 1.5 μm.

[0022] Preferably, in step (3), the ball-to-material ratio of wet ball milling is 10:1, the rotation speed is 300 rpm, and the time is 3-5 h; the aqueous dispersion medium is deionized water, the dispersant is Dispex AA4040, and the binder is polyvinyl alcohol.

[0023] Preferably, the inlet temperature of the spray drying in step (4) is 175-185℃ and the outlet temperature is 90-100℃, and spherical particles with a particle size of 35-85μm are collected.

[0024] Preferably, the multi-stage heating-holding system in step (4) is as follows: heating to 190-210°C and holding for 30 minutes, then heating to 330-370°C and holding for 30 minutes, then heating to 580-620°C and holding for 60 minutes, then heating to 1100-1140°C and holding for 30 minutes, and then cooling with the furnace.

[0025] Preferably, in step (5), the mass ratio of tungsten carbide powder, titanium diboride powder, titanium carbide powder, high-entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder is 380-430:180-220:70-90:200-240:3-5:3-5:2-3.

[0026] Preferably, the vacuum impregnation in step (5) is carried out in a cyclic manner: the absolute pressure of the impregnation tank is reduced to 1-25 kPa and held for 3 minutes, then restored to 100 kPa and held for 1 minute as one cycle, and repeated 2-4 times.

[0027] Preferably, the dipping speed in step (5) is 90-110 mm·min. -1 The gap between the coating and the brush is 110-130μm, and the drying temperature is 75-85℃ for 3-5 hours.

[0028] Preferably, the hot pressing sintering temperature in step (6) is 1380-1420℃, the pressure is 33-37MPa, and the holding time is 20-30min.

[0029] Furthermore, the present invention also provides a wear-resistant and lightweight cemented carbide material, which is obtained by the above-mentioned method for preparing wear-resistant and lightweight cemented carbide material.

[0030] Furthermore, the present invention also provides an application of a wear-resistant, lightweight cemented carbide material for the manufacture of anti-slip nails.

[0031] The beneficial effects of this invention are:

[0032] This invention achieves a significant improvement in the performance of cemented carbide materials through unique material composition design and a multi-step preparation process. Based on the introduction of double-grafted modified reduced graphene oxide, an effective reinforcing network is formed in the matrix. Specific functional groups on the graphene sheets generate strong interfacial interactions with the hard and binder phases, greatly improving interfacial bonding. This not only effectively hinders crack propagation and promotes crack deflection and bridging, thereby significantly improving the fracture toughness and impact resistance of the material, but also allows stress to be transmitted more uniformly within the material, avoiding early failure caused by localized stress concentration.

[0033] This invention utilizes a high-entropy alloy as the binder phase, leveraging its unique cocktail effect and slow diffusion effect. This multi-principal alloy system forms a well-wetting and firmly bonded interface with the hard phase during sintering, while its inherent high strength and hardness further strengthen the matrix. Compared to traditional cobalt-based binders, this high-entropy alloy binder phase maintains good toughness while imparting higher stiffness and resistance to plastic deformation, enabling the material to maintain shape stability under high-load wear and significantly reducing wear rate.

[0034] This invention innovatively employs a two-stage coating and vacuum impregnation cycle process to successfully construct a gradient structure with a continuous transition from the inside to the outside. After impregnation and coating with a supplementary slurry, the internal interconnected pores of the initially dense preform are effectively filled, and a dense layer with optimized composition and properties is formed on the surface. This structure ensures a highly efficient increase in the material's bulk density, eliminates internal defects, and increases the difficulty of crack initiation. Simultaneously, the gradient structure optimizes the distribution of thermal stress, improves the material's thermal shock resistance, and exhibits greater stability under frictional heating conditions.

[0035] The present invention combines titanium carbide and titanium diboride in a specific ratio in the hard phase, resulting in a synergistic reinforcing effect. The excellent thermal conductivity and chemical stability of titanium diboride, combined with the high hardness of titanium carbide, jointly construct a robust and efficient reinforcing skeleton. This composite hard phase skeleton not only provides extremely high wear resistance, but its excellent thermal conductivity network also facilitates rapid dissipation of frictional heat, avoiding softening of the binder phase and performance degradation caused by localized overheating, thus ensuring the long-term durability of the material under harsh operating conditions. In summary, the material prepared by the present invention achieves high strength, high toughness, high wear resistance, and excellent thermal management capabilities while maintaining lightweight properties. Furthermore, it enables anti-slip studs to achieve lightweight while possessing excellent long-term wear resistance, high impact reliability, and outstanding thermal stability, meeting the increasingly stringent requirements for safety and durability in modern transportation. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0037] Example 1:

[0038] Step 1: Preparation of grafted reduced graphene oxide powder

[0039] Weigh 120 mL of graphene oxide dispersion (1-5 layers of graphene oxide, concentration 15 mg / mL, average sheet diameter 1.5 μm) and place it in an ice-water bath at 0-5°C and stir for 10 min. Add 3 g of p-aminophenylphosphonic acid and dropwise add 35 mL of hydrochloric acid solution (concentration 37 wt%). Continue stirring for 10 min, add 1.4 g of sodium nitrite, maintain the temperature at 0-5°C and react for 30 min. Then add 2.5 g of p-methylaniline and continue stirring for 10 min. Add 1.4 g of sodium nitrite and maintain the temperature at 0-5°C and react for 30 min. Finally, add 50 mL of hydrazine monohydrate solution (concentration 25 wt%), reduce in a 95°C water bath for 45 min, cool naturally, centrifuge and wash until neutral, and vacuum dry at 60°C for 12 h to obtain double-grafted reduced graphene oxide powder.

[0040] Step 2: Preparation of high-entropy alloy pre-alloyed powder

[0041] Weigh out 107g of aluminum powder (average particle size 2.4μm), 233g of cobalt powder (average particle size 1.6μm), 206g of chromium powder (average particle size 1.4μm), 221g of iron powder (average particle size 5.7μm), 232g of nickel powder (average particle size 2.6μm), 3g of boron powder (average particle size 0.8μm), and 4g of silicon powder (average particle size 0.5μm). Use 200mL of ethanol as an additive. Fill a planetary ball mill with stainless steel balls at a ball-to-material ratio of 10:1 and ball mill at 300rpm for 14h. Stop the mill every 2h to cool down. Dry the powder at 60°C under argon protection to obtain high-entropy alloy pre-alloyed powder.

[0042] Step 3: Preparation of composite slurry

[0043] Weigh 620g of tungsten carbide powder (average particle size 0.8μm), 100g of titanium diboride powder (average particle size 3μm), 60g of titanium carbide powder (average particle size 2μm), 40g of high-entropy alloy pre-alloyed powder, 3g of vanadium carbide powder (average particle size 2μm), weigh 3g of chromium tricarbide powder (average particle size 1.5μm), and 1.0g of double-grafted reduced graphene oxide powder. Add 820mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray Poval, PVA-205). The ball-to-particle ratio is 10:1. Wet mill at 300rpm for 3h. Filter the slurry through a 200-mesh sieve to obtain the composite slurry.

[0044] Step 4: Preparation of the initial dense billet

[0045] The composite slurry is fed into a spray drying tower with an inlet temperature of 175°C and an outlet temperature of 90°C. Spherical particles with a particle size of 35-75µm are collected and placed into a mold (internal cavity size 60mm×10mm×5mm). The mold is heated to 190°C and held for 30min in an argon atmosphere, then heated to 330°C and held for 30min, then heated to 580°C and held for 60min, then heated to 1100°C and held for 30min, and then cooled in the furnace to obtain a preliminary dense billet.

[0046] Step 5: Preparation of the secondary coated preform

[0047] Weigh out 430g of tungsten carbide powder (average particle size 0.8μm), 180g of titanium diboride powder (average particle size 3μm), 70g of titanium carbide powder (average particle size 2μm), 200g of high-entropy alloy pre-alloyed powder, 3g of vanadium carbide powder (average particle size 2μm), 3g of chromium tricarbide powder (average particle size 1.5μm), and 2.0g of double-grafted reduced graphene oxide powder. Add 620mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray). Poval (PVA-205), ball-to-material ratio 10:1, wet milled at 170 rpm for 2 hours to obtain a filler slurry. The filler slurry was poured into a vacuum impregnation tank, and the initially dense preform was suspended and completely immersed without touching the bottom of the tank. The vacuum system was started to reduce the absolute pressure in the tank to 25 kPa and hold for 3 minutes, then restored to 100 kPa and held for 1 minute as one cycle. Two cycles were completed to remove air from the connecting holes and allow the filler slurry to enter the channels. The preform was removed and dip-coated above the filler slurry at a lifting speed of 90 mm / min. Immediately afterward, the excess slurry on the surface was scraped off in the same direction with a gap of 110 μm on an adjustable scraper to form a wet film. The preform was allowed to stand for 8 minutes to degas and then dried at 75°C for 3 hours to obtain a secondary coated preform.

[0048] Step Six: Hot Press Densification

[0049] The secondary coated blank is placed in a vacuum hot press furnace, heated to 1380°C and held at 33MPa pressure for 20 minutes, then cooled to room temperature and demolded to obtain a wear-resistant and lightweight cemented carbide material. The wear-resistant and lightweight cemented carbide material is wire-cut into anti-slip nail blanks, machined to form working ends with micro-rounded corners, vacuum tempered at 640°C for 50 minutes, cooled to room temperature, and sandblasted with 240-mesh brown corundum to obtain anti-slip nails.

[0050] Example 2:

[0051] Step 1: Preparation of grafted reduced graphene oxide powder

[0052] Weigh 120 mL of graphene oxide dispersion (1-5 layers of graphene oxide, concentration 15 mg / mL, average sheet diameter 1.5 μm) and place it in an ice-water bath at 0-5°C and stir for 10 min. Add 4 g of p-aminophenylphosphonic acid and dropwise add 40 mL of hydrochloric acid solution (concentration 37 wt%). Continue stirring for 10 min, add 1.6 g of sodium nitrite, maintain the temperature at 0-5°C and react for 30 min. Then add 3 g of p-methylaniline and continue stirring for 10 min. Add 1.6 g of sodium nitrite and maintain the temperature at 0-5°C and react for 30 min. Finally, add 60 mL of hydrazine monohydrate solution (concentration 25 wt%), reduce in a 95°C water bath for 45 min, cool naturally, centrifuge and wash until neutral, and vacuum dry at 60°C for 12 h to obtain double-grafted reduced graphene oxide powder.

[0053] Step 2: Preparation of high-entropy alloy pre-alloyed powder

[0054] Weigh out 107g of aluminum powder (average particle size 2.4μm), 233g of cobalt powder (average particle size 1.6μm), 206g of chromium powder (average particle size 1.4μm), 221g of iron powder (average particle size 5.7μm), 232g of nickel powder (average particle size 2.6μm), 4g of boron powder (average particle size 0.8μm), and 6g of silicon powder (average particle size 0.5μm). Use 200mL of ethanol as an additive. Fill a planetary ball mill with stainless steel balls at a ball-to-material ratio of 10:1 and ball mill at 300rpm for 16h. Stop the mill every 2h to cool down. Dry the powder at 60°C under argon protection to obtain high-entropy alloy pre-alloyed powder.

[0055] Step 3: Preparation of composite slurry

[0056] Weigh 600g of tungsten carbide powder (average particle size 0.8μm), 120g of titanium diboride powder (average particle size 3μm), 80g of titanium carbide powder (average particle size 2μm), 60g of high-entropy alloy pre-alloyed powder, 4g of vanadium carbide powder (average particle size 2μm), 4g of chromium tricarbide powder (average particle size 1.5μm), and 1.5g of double-grafted reduced graphene oxide powder. Add 850mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray Poval, PVA-205). The ball-to-particle ratio is 10:1. Wet mill at 300rpm for 4 hours. Filter the slurry through a 200-mesh sieve to obtain the composite slurry.

[0057] Step 4: Preparation of the initial dense billet

[0058] The composite slurry is fed into a spray drying tower with an inlet temperature of 180°C and an outlet temperature of 95°C. Spherical particles with a particle size of 40-80µm are collected and placed into a mold (internal cavity size 60mm×10mm×5mm). The mold is heated to 200°C and held for 30min in an argon atmosphere, then heated to 350°C and held for 30min, then heated to 600°C and held for 60min, then heated to 1120°C and held for 30min, and then cooled in the furnace to obtain a preliminary dense billet.

[0059] Step 5: Preparation of the secondary coated preform

[0060] Weigh out 400g of tungsten carbide powder (average particle size 0.8μm), 200g of titanium diboride powder (average particle size 3μm), 80g of titanium carbide powder (average particle size 2μm), 220g of high-entropy alloy pre-alloyed powder, 4g of vanadium carbide powder (average particle size 2μm), 4g of chromium tricarbide powder (average particle size 1.5μm), and 2.5g of double-grafted reduced graphene oxide powder. Add 650mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray). Poval (PVA-205), ball-to-particle ratio 10:1, wet milled at 180 rpm for 3 hours to obtain a filler slurry. The filler slurry was poured into a vacuum impregnation tank, and the initially dense preform was suspended and completely immersed without touching the bottom of the tank. The vacuum system was started to reduce the absolute pressure in the tank to 20 kPa and hold for 3 minutes, then restored to 100 kPa and hold for 1 minute as one cycle. Three cycles were completed to remove air from the connecting holes and allow the filler slurry to enter the channels. The preform was removed and impregnated above the filler slurry at a lifting speed of 100 mm / min. Immediately afterward, the excess slurry on the surface was scraped off in the same direction with a gap of 120 μm on an adjustable scraper to form a wet film. The preform was allowed to stand for 10 minutes to degas and then dried at 80°C for 4 hours to obtain a secondary coated preform.

[0061] Step Six: Hot Press Densification

[0062] The secondary coated blank is placed in a vacuum hot press furnace, heated to 1400°C and held at 35MPa pressure for 25 minutes, then cooled to room temperature and demolded to obtain a wear-resistant and lightweight cemented carbide material. The wear-resistant and lightweight cemented carbide material is wire-cut into anti-slip nail blanks, machined to form working ends with micro-rounded corners, vacuum tempered at 650°C for 60 minutes, cooled to room temperature, and sandblasted with 240-mesh brown corundum to obtain anti-slip nails.

[0063] Example 3:

[0064] Step 1: Preparation of grafted reduced graphene oxide powder

[0065] Weigh 120 mL of graphene oxide dispersion (1-5 layers of graphene oxide, concentration 15 mg / mL, average sheet diameter 1.5 μm) and place it in an ice-water bath at 0-5°C and stir for 10 min. Add 5 g of p-aminophenylphosphonic acid and dropwise add 45 mL of hydrochloric acid solution (concentration 37 wt%). Continue stirring for 10 min, add 1.8 g of sodium nitrite, maintain the temperature at 0-5°C and react for 30 min. Then add 3.5 g of p-methylaniline and continue stirring for 10 min. Add 1.8 g of sodium nitrite and maintain the temperature at 0-5°C and react for 30 min. Finally, add 70 mL of hydrazine monohydrate solution (concentration 25 wt%), reduce in a 95°C water bath for 45 min, cool naturally, centrifuge and wash until neutral, and vacuum dry at 60°C for 12 h to obtain double-grafted reduced graphene oxide powder.

[0066] Step 2: Preparation of high-entropy alloy pre-alloyed powder

[0067] Weigh out 107g of aluminum powder (average particle size 2.4μm), 233g of cobalt powder (average particle size 1.6μm), 206g of chromium powder (average particle size 1.4μm), 221g of iron powder (average particle size 5.7μm), 232g of nickel powder (average particle size 2.6μm), 5g of boron powder (average particle size 0.8μm), and 8g of silicon powder (average particle size 0.5μm). Use 200mL of ethanol as an additive. Fill a planetary ball mill with stainless steel balls at a ball-to-material ratio of 10:1 and ball mill at 300rpm for 18h. Stop the mill every 2h to cool down. Dry the powder at 60°C under argon protection to obtain high-entropy alloy pre-alloyed powder.

[0068] Step 3: Preparation of composite slurry

[0069] Weigh out 580g of tungsten carbide powder (average particle size 0.8μm), 140g of titanium diboride powder (average particle size 3μm), 100g of titanium carbide powder (average particle size 2μm), 80g of high-entropy alloy pre-alloyed powder, 5g of vanadium carbide powder (average particle size 2μm), 5g of chromium tricarbide powder (average particle size 1.5μm), and 2.0g of double-grafted reduced graphene oxide powder. Add 880mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray Poval, PVA-205). The ball-to-particle ratio is 10:1. Wet mill at 300rpm for 5h. Filter the slurry through a 200-mesh sieve to obtain the composite slurry.

[0070] Step 4: Preparation of the initial dense billet

[0071] The composite slurry is fed into a spray drying tower with an inlet temperature of 185°C and an outlet temperature of 100°C. Spherical particles with a particle size of 45-85µm are collected and placed into a mold (internal cavity size 60mm×10mm×5mm). The mold is heated to 210°C and held for 30min in an argon atmosphere, then heated to 370°C and held for 30min, then heated to 620°C and held for 60min, then heated to 1140°C and held for 30min, and then cooled in the furnace to obtain a preliminary dense billet.

[0072] Step 5: Preparation of the secondary coated preform

[0073] Weigh out 380g of tungsten carbide powder (average particle size 0.8μm), 220g of titanium diboride powder (average particle size 3μm), 90g of titanium carbide powder (average particle size 2μm), 240g of high-entropy alloy pre-alloyed powder, 5g of vanadium carbide powder (average particle size 2μm), 5g of chromium tricarbide powder (average particle size 1.5μm), and 3.0g of double-grafted reduced graphene oxide powder. Add 680mL of deionized water, 2g of dispersant Dispex AA4040, and 2g of polyvinyl alcohol powder (Kuraray). Poval (PVA-205), ball-to-particle ratio 10:1, wet milled at 190 rpm for 4 hours to obtain a filler slurry. The filler slurry was poured into a vacuum impregnation tank, and the initially dense preform was suspended and completely immersed without touching the bottom of the tank. The vacuum system was started to reduce the absolute pressure in the tank to 15 kPa and hold for 3 minutes, then restored to 100 kPa and hold for 1 minute as one cycle. Four cycles were completed to remove air from the connecting holes and allow the filler slurry to enter the channels. The preform was removed and impregnated above the filler slurry at a lifting speed of 110 mm / min. Immediately afterward, the excess slurry on the surface was scraped off in the same direction with a gap of 130 μm on an adjustable scraper to form a wet film. The preform was allowed to stand for 12 minutes to degas and then dried at 85°C for 5 hours to obtain a secondary coated preform.

[0074] Step Six: Hot Press Densification

[0075] The secondary coated blank is placed in a vacuum hot press furnace, heated to 1420°C and held at 37MPa pressure for 30 minutes, then cooled to room temperature and demolded to obtain a wear-resistant and lightweight cemented carbide material. The wear-resistant and lightweight cemented carbide material is wire-cut into anti-slip nail blanks, machined to form working ends with micro-rounded corners, vacuum tempered at 660°C for 70 minutes, cooled to room temperature, and sandblasted with 240-mesh brown corundum to obtain anti-slip nails.

[0076] Comparative Example 1:

[0077] The difference between Comparative Example 1 and Example 2 is that p-aminophenylphosphonic acid is not added in step one, while the other conditions are the same as in Example 2.

[0078] Comparative Example 2:

[0079] The difference between Comparative Example 2 and Example 2 is that p-methylaniline is not added in step one, while the other conditions are the same as in Example 2.

[0080] Comparative Example 3:

[0081] The difference between Comparative Example 3 and Example 2 is that hydrazine monohydrate solution is not added in step one, while the other conditions are the same as in Example 2.

[0082] Comparative Example 4:

[0083] The difference between Comparative Example 4 and Example 2 is that in step three, titanium carbide powder of equal mass is used instead of titanium diboride powder, that is, the amount of titanium diboride powder is adjusted from 120g to 0g, the total amount of titanium carbide powder is adjusted from 80g to 200g, the total solid phase mass remains unchanged, and the other conditions are the same as in Example 2.

[0084] Comparative Example 5:

[0085] The difference between Comparative Example 5 and Example 2 is that: in step five, no vacuum impregnation cycle is performed, only one dip coating and scraping coating are performed, and the other conditions are the same as in Example 2.

[0086] Comparative Example 6:

[0087] The difference between Comparative Example 6 and Example 2 is that 2.5g of double-grafted reduced graphene oxide powder was added only in step five (secondary coating slurry), and not in step three. The other conditions were the same as in Example 2.

[0088] Comparative Example 7:

[0089] The difference between Comparative Example 7 and Example 2 is that step five is omitted, that is, the initial dense billet from step four is directly hot-pressed to densify, while the other conditions are the same as in Example 2.

[0090] Performance testing:

[0091] The following material performance tests are all for cemented carbide materials after hot pressing densification in step six and before vacuum tempering and sandblasting.

[0092] Density: The density of cemented carbide materials was determined by the Archimedes method according to GB / T 3850-2015. The mass of the sample was taken in deionized water and the dry mass was taken in air. Before the test, the apparatus was calibrated and the medium was degassed according to the standard. Each sample was repeated 3 times and the average value was taken. The results are shown in Table 1.

[0093] Vickers hardness: The Vickers hardness of cemented carbide materials was determined according to GB / T 7997-2014. The load was F=294.2N (HV30) and held for 15s. The average value of 5 indentations at a distance of ≥2.5×diagonal from the edge was taken. The results are shown in Table 1.

[0094] Transverse fracture strength: The transverse fracture strength of cemented carbide materials was determined according to GB / T 3851-2015. Rectangular A-type three-point bending specimens were prepared (samples were prepared according to standard dimensions and chamfer requirements). The span was set according to the standard. The loading rate was 2 mm·min. -1 The maximum fracture load was recorded and the calculated strength was taken. The average value of 5 pieces in each group was taken. The results are shown in Table 1.

[0095] Barcol toughness: The Barcol toughness of cemented carbide materials was determined according to GB / T 33819-2017. Four corner indentations were made on the polished surface with an HV30 load. The total length of the four cracks was measured and the Barcol toughness was calculated according to the standard formula. The average of three locations was taken for each piece. The results are shown in Table 1.

[0096] Room temperature impact toughness: The room temperature impact toughness of cemented carbide materials was determined according to GB / T 1817-2017. Notched impact specimens were prepared according to the standard, and the test was carried out at 23±2°C. The absorbed energy was recorded and the impact toughness value was calculated. The average value of 5 specimens in each group was taken. The results are shown in Table 1.

[0097] Wear resistance: The wear resistance of cemented carbide materials was determined according to GB / T 34501-2017. The dry sand-rubber wheel procedure (method A) was selected, with a load of 130N, the standard sand flow rate was set according to the specification, and the wear distance was 6000m. The mass loss was recorded, and the average value of 5 pieces in each group was taken. The results are shown in Table 1.

[0098] Thermal diffusivity: The thermal diffusivity of cemented carbide materials was tested using the flash method according to GB / T 11108-2017. A Φ10mm×2mm thin circular disc with graphite backing was used. The thermal diffusivity was measured at room temperature. The average value of 5 pieces in each group was taken. The results are shown in Table 1.

[0099] Table 1 Performance Test Results

[0100]

[0101] Data Analysis:

[0102] As can be seen from the data in Examples 1-3 in Table 1, the wear-resistant and lightweight cemented carbide prepared by this invention exhibits excellent performance in terms of strength, toughness, and wear resistance. When the ratio of difunctional group-grafted reduced graphene oxide to titanium diboride / titanium carbide is at a moderate level, and when combined with vacuum impregnation cycle and high-entropy alloy pre-alloying, the material's interfacial wettability, core-edge layer continuity, and densification rate are improved simultaneously. Cracks tend to deflect and bridge under wear and impact loads, and the internal heat diffusion is more uniform, which helps to suppress the propagation of microcracks. When the proportion of hard phase continues to increase, although the surface indentation resistance increases, the excessive hardening of the interface and the dilution of the thermal conductivity network prevent the strength and wear resistance from increasing accordingly. Therefore, it can be seen that the present invention achieves a balanced comprehensive performance under the premise of lightweight by controlling the timing of the addition of double-grafted reduced graphene oxide through first template and then reinforcement, and by using the rewetting effect of aluminum-cobalt-chromium-iron-nickel high-entropy alloy in conjunction with the refining effect of titanium diboride / titanium carbide, which is suitable for long-term service of anti-slip studs under combined working conditions of dry sand, low temperature and intermittent impact.

[0103] As can be seen from the data in Example 2 and Comparative Example 1 in Table 1, the lack of p-aminophenylphosphonic acid results in insufficient inorganic affinity anchors in the slurry stage, leading to a decrease in the fixation ability of reduced graphene oxide at the interface, discontinuous densification channels, and a simultaneous decline in strength and wear resistance. The main reason is the lack of synergistic coordination between phosphate groups and the hard / binder phases, which increases the liquid phase wetting angle, reduces pore closure efficiency, and makes cracks more prone to propagate along weak interfaces. Therefore, the role of p-aminophenylphosphonic acid in interface templating is irreplaceable.

[0104] As can be seen from the data in Table 1 for Example 2 and Comparative Example 2, even without p-methylaniline, the coating surface remains dense, but toughness and wear resistance are difficult to achieve simultaneously. The main reason is the lack of hydrophobic regulation at the methyl end, leading to easy re-agglomeration of the lamellar layers, resulting in uneven thickness distribution and making microcracks more prone to penetration under wear. Therefore, the double grafting of phosphate and methyl groups is not a simple superposition, but rather a synergistic effect in wetting and dispersion.

[0105] As can be seen from the data in Example 2 and Comparative Example 3 in Table 1, the hardness and strength of the material decreased simultaneously without hydrazine monohydrate reduction. The main reason is that the graphene oxide was not sufficiently deoxygenated, resulting in insufficient electromagnetic and chemical inertness, making it difficult to form an efficient stress transfer path, and inducing gas evolution and micropores in the early stages of sintering. Therefore, chemical reduction is a key step in achieving the double grafting effect.

[0106] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, replacing titanium diboride with titanium carbide of equal mass slightly increases the hardness but decreases the wear resistance and strength. The main reason is that the interface energy between titanium carbide and the binder phase is higher, the thermal diffusion channels are blocked, local heating and boundary debonding are exacerbated during wear, and cracks are more likely to penetrate in a straight line. Therefore, the combination of titanium diboride and titanium carbide has an unexpectedly synergistic effect compared to titanium carbide alone.

[0107] As can be seen from the data in Example 2 and Comparative Example 5 in Table 1, after canceling the vacuum impregnation cycle, the strength, toughness, and thermal diffusivity all decreased significantly, and the mass loss increased significantly. The main reason is that the feed slurry under vacuum drive did not fully enter the interconnected channels, making it difficult for the pores to close, resulting in stress concentration and increased abrasive wedging. Therefore, cyclic impregnation is not an optional process, but a key step that determines bulk density and interface integrity.

[0108] As can be seen from the data in Example 2 and Comparative Example 6 in Table 1, when reduced graphene oxide is added only in the secondary coating stage, the hardness can be maintained, but the overall strength, toughness, and wear resistance are inferior. The main reason is the lack of pre-spray templating; interface regulation only occurs on the surface layer, making it difficult to form a synergistic network that penetrates the thickness. Therefore, the dual-time addition of templating first and then reinforcement produces a 1+1>2 effect.

[0109] As can be seen from the data in Example 2 and Comparative Example 7 in Table 1, although the apparent density is lower after deleting step five, the strength and wear resistance deteriorate sharply. The main reason is that the pores were not effectively filled by the impregnated filler, resulting in pseudo-lightweighting accompanied by structural defects, and cracks propagated rapidly under impact and abrasion.

[0110] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a wear-resistant, lightweight cemented carbide material, characterized in that, Includes the following steps: (1) Preparation of double-grafted reduced graphene oxide powder: The graphene oxide dispersion was stirred at 0-5℃, and the first diazotization grafting was carried out with p-aminophenylphosphonic acid and diazotizing agent, and the second diazotization grafting was carried out with p-methylaniline and diazotizing agent. Then, a reducing agent was added for reduction treatment, and the powder was obtained by washing and drying. (2) Preparation of high-entropy alloy pre-alloyed powder: aluminum powder, cobalt powder, chromium powder, iron powder, nickel powder and boron powder and silicon powder are subjected to planetary ball milling pre-alloying treatment in an organic solvent, and then dried to obtain high-entropy alloy pre-alloyed powder; (3) Preparation of composite slurry: Tungsten carbide powder, titanium diboride powder, titanium carbide powder, high entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder are added to an aqueous dispersion medium, a dispersant and an organic binder are added, and the mixture is wet-milled and sieved to obtain a composite slurry. (4) Preparation of primary dense blank: The composite slurry is spray-dried to obtain spherical particles, which are then loaded into a mold and sintered under a protective atmosphere according to a multi-stage heating-holding regime to obtain the primary dense blank; (5) Secondary coating: Tungsten carbide powder, titanium diboride powder, titanium carbide powder, high entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder and double-grafted reduced graphene oxide powder are prepared into a feed slurry. The initial dense blank is placed in the feed slurry for vacuum impregnation. The impregnated blank is then dip-coated, scraped and dried to obtain a secondary coated blank. (6) Hot pressing densification: The secondary coated blank is placed in a vacuum hot press furnace for hot pressing sintering, cooled and demolded to obtain wear-resistant and lightweight cemented carbide material; In step (1), the mass ratio of graphene oxide, p-aminophenylphosphonic acid, and p-methylaniline is 1.8:3-5:2.5-3.5; in step (3), the mass ratio of tungsten carbide powder, titanium diboride powder, titanium carbide powder, high-entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder, and double-grafted reduced graphene oxide powder is 580-620:100-150:60-100:40-80:3-5:3-5:1-2; in step (5), the mass ratio of tungsten carbide powder, titanium diboride powder, titanium carbide powder, high-entropy alloy pre-alloyed powder, vanadium carbide powder, chromium tricarbide powder, and double-grafted reduced graphene oxide powder is 380-430:180-220:70-90:200-240:3-5:3-5:2-3.

2. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (1), two diazotizations were performed at 0-5℃ using a hydrochloric acid / sodium nitrite system, followed by reduction with 25wt% hydrazine monohydrate in a 95℃ water bath for 45 min, and then vacuum drying at 60℃ for 12 h.

3. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (2), the mass ratio of aluminum powder, cobalt powder, chromium powder, iron powder, nickel powder, boron powder and silicon powder is 107:233:206:221:232:3-5:4-8.

4. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (3), the average particle size of tungsten carbide powder is 0.8 μm, the average particle size of titanium diboride powder is 3 μm, the average particle size of titanium carbide powder is 2 μm, the average particle size of vanadium carbide powder is 2 μm, and the average particle size of chromium tricarbide powder is 1.5 μm.

5. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (4), the spray drying process involves an inlet temperature of 175-185℃ and an outlet temperature of 90-100℃, collecting spherical particles with a particle size of 35-85μm.

6. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (4), the multi-stage heating-holding system is as follows: heat up to 190-210°C and hold for 30 minutes, then heat up to 330-370°C and hold for 30 minutes, then heat up to 580-620°C and hold for 60 minutes, then heat up to 1100-1140°C and hold for 30 minutes before cooling with the furnace.

7. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, In step (5), the vacuum impregnation is carried out in a cyclic manner: the absolute pressure of the impregnation tank is reduced to 1-25 kPa and maintained for 3 minutes, then restored to 100 kPa and maintained for 1 minute as one cycle, and repeated 2-4 times; the lifting speed of the impregnation coating is 90-110 mm·min. -1 The gap between the coating and the brush is 110-130μm, and the drying temperature is 75-85℃ for 3-5 hours.

8. The method for preparing the wear-resistant, lightweight cemented carbide material according to claim 1, characterized in that, The hot pressing sintering temperature in step (6) is 1380-1420℃, the pressure is 33-37MPa, and the holding time is 20-30min.

9. A wear-resistant, lightweight cemented carbide material, characterized in that, It is obtained by the preparation method of the wear-resistant and lightweight cemented carbide material according to any one of claims 1-8.

10. An application of the wear-resistant, lightweight cemented carbide material according to claim 9 for the manufacture of anti-slip nails.

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