A hard alloy anti-skid nail with high wear resistance and excellent anti-skid performance and a preparation method thereof

Abstract

The present application relates to the technical field of hard alloy, in particular to a high wear-resistant and excellent anti-skid hard alloy stud and a preparation method thereof. In view of the early failure problem of the existing WC-Co stud caused by cobalt phase pool, uneven interface wetting and nail tip rounding under the alternating impact of ice-water-sand, the tungsten carbide powder is surface modified in dopamine-acrylic acid weak acid aerobic buffer solution, then five ethoxy tantalum and oxalic acid tantalum aqueous solution are introduced in sequence, the double tantalum precursor space preset structure is formed through coordination anchoring, aging and carboxyl adsorption, and then the structure is compounded with cobalt precursor and carbon black, and then the structure is pressed and sintered in sections, so that cobalt is preferentially limited in the interface area of tungsten carbide particles and a tantalum-rich carbide hardening layer is generated; the obtained stud can maintain high wear resistance while significantly inhibiting early rounding and micro-chipping, and has excellent grip stability on ice and wet road surface.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, specifically to a cemented carbide anti-slip nail with high wear resistance and excellent anti-slip performance, and its preparation method. Background Technology

[0002] Hard alloy studs are key components of winter tires and snow-covered vehicles, typically composed of a tungsten carbide (WC) hard phase and a cobalt (Co) binder phase. In complex service environments involving alternating periods of icy and snowy roads, meltwater-covered roads, and exposed gravel, studs must withstand the low-friction impact of ice, the lubrication of meltwater, and the high-stress cutting of gravel. In existing WC-Co studs, during the sintering process, the cobalt binder phase tends to flow and aggregate during the liquid-phase sintering stage, forming coarse, pool-like structures with dimensions reaching hundreds of nanometers or even micrometers. While these locally cobalt-rich regions can mitigate crack propagation to some extent, they lead to uneven wetting at the interface between tungsten carbide particles, weakening the direct bonding strength between particles. When the stud tip repeatedly contacts the ice layer, the tungsten carbide particles surrounding the pool-like cobalt phase are prone to detachment or micro-chipping, causing the stud tip edges to quickly round off, thus reducing its grip on ice.

[0003] To improve the impact resistance of anti-slip studs, a common approach is to increase the cobalt content. Increasing the proportion of the cobalt phase can enhance the toughness of the material and reduce the risk of chipping. However, increasing the cobalt content significantly reduces the wear resistance of cemented carbide because the soft cobalt phase is more easily worn away by gravel, causing tungsten carbide particles to lose support and peel off prematurely. This contradiction between cobalt content and wear resistance is particularly prominent under dynamic conditions where ice, snowmelt, and exposed gravel alternate: simply increasing the cobalt content alleviates brittleness but significantly shortens the effective grip time of the stud tip on the ice surface; conversely, reducing the cobalt content improves wear resistance, but micro-chipping occurs frequently, failing to meet the long service life requirement. In existing technologies, adding grain growth inhibitors (such as vanadium carbide and chromium carbide) can control the tungsten carbide grain size to some extent, but these inhibitors mainly act on grain boundary migration during sintering and have limited control over the distribution morphology of the cobalt binder phase, failing to fundamentally solve the problem of cobalt phase pooling and the resulting uneven interface wetting.

[0004] Furthermore, during service, the stress types experienced by the spike tip edges and the particle contact neck area differ significantly. The spike tip edges are primarily subjected to cutting and abrasion from ice and gravel, requiring high local hardness and wear resistance; while the particle contact neck area bears the burden of impact load transmission, requiring a fine and continuously distributed binder phase to buffer stress and prevent crack initiation. Existing technologies often treat cemented carbide as a homogeneous material in overall composition design, neglecting the different failure modes in these two critical areas. This results in anti-slip studs failing to simultaneously achieve wear resistance and chipping resistance under complex working conditions. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, and its preparation method, so as to solve the problem of suppressing early rounding and micro-chipping of WC-Co anti-slip studs under alternating impacts of ice-water-gravel without reducing wear resistance.

[0006] To achieve the above objectives, the present invention provides a method for preparing a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, comprising the following steps:

[0007] S1: Tungsten carbide powder is subjected to an oxidative copolymerization reaction in a weakly acidic aerobic buffer solution containing dopamine hydrochloride and acrylic acid to form an oligomeric guiding layer containing catechol and carboxyl groups on the surface of tungsten carbide, thereby obtaining modified tungsten carbide powder.

[0008] S2: Surface-modified tungsten carbide powder is dispersed in anhydrous ethanol, and tantalum pentaethoxy is added under dry nitrogen protection. After stirring, aging liquid is sprayed into the reaction system for sealed aging. After drying, it is ready for use.

[0009] S3: Disperse the powder obtained in S2 in deionized water, add tantalum oxalate aqueous solution and continue stirring, then dry for later use;

[0010] S4: Cobalt acetate tetrahydrate and carbon black are dispersed in a mixed solvent, mixed and then sprayed onto the powder obtained in S3. After mixing and drying, the mixture is ready for use.

[0011] S5: Add paraffin wax to the powder obtained in S4, mix and granulate, and press into nail core blanks;

[0012] S6: Sinter the blank obtained in S5 to obtain cemented carbide anti-slip nails.

[0013] Preferably, the weight ratio of tungsten carbide powder, dopamine hydrochloride and acrylic acid in step S1 is 100g:0.20-0.28g:0.60-0.84g.

[0014] Preferably, the tungsten carbide powder in step S1 has a Fisher particle size of 0.50-0.60 μm, a maximum oxygen content of 0.40%, and a maximum free carbon content of 0.08%.

[0015] Preferably, the tungsten carbide powder in step S1 needs to be dried before use.

[0016] Preferably, the acrylic acid described in step S1 needs to be treated by passing it through a short glass column filled with alkaline alumina before use.

[0017] Preferably, the weakly acidic pH in step S1 is 5.0-5.4.

[0018] Preferably, the copolymerization reaction in step S1 is carried out by stirring at 25-30°C for 1.8-2.2 hours, and then heating to 33-37°C to continue the reaction for 0.8-1.2 hours.

[0019] Preferably, the spraying in step S2 is performed in an atomized manner.

[0020] Preferably, the aging solution in step S2 is a mixture of anhydrous ethanol and deionized water, wherein the weight ratio of anhydrous ethanol to deionized water is 0.77-1.05g:0.03-0.05g.

[0021] Preferably, the sealing aging temperature in step S2 is 35-45℃ and the time is 25-35min.

[0022] Preferably, in step S2, the weight of the surface-modified tungsten carbide powder is 100g, and the amount of aging solution injected is 0.80-1.10g.

[0023] Preferably, the tantalum oxalate aqueous solution in step S3 is a water-based clear solution with a tantalum content of 12%.

[0024] Preferably, the mixed solvent in step S4 is a mixed solution of anhydrous ethanol and deionized water.

[0025] Preferably, the mixing speed in step S4 is 50-70 rpm and the mixing time is 35-45 min.

[0026] Preferably, in step S5, the amount of paraffin added is 0.9-1.1g, based on the weight of 100g of the powder obtained in S4.

[0027] Preferably, the mixing temperature in step S5 is 68-72℃ and the mixing time is 25-35 min.

[0028] Preferably, the pressing pressure in step S5 is 210-230 MPa.

[0029] Preferably, the sintering process in step S6 involves first heating to 115-125°C at a vacuum of 400-600 Pa at a rate of 1.5-2.5°C / min and holding for 0.8-1.2 h to remove residual solvent; then heating to 270-290°C at a rate of 0.8-1.2°C / min and holding for 0.8-1.2 h to remove paraffin; then heating to 410-430°C at a rate of 0.8-1.2°C / min and holding for 0.8-1.2 h, followed by switching to high-purity hydrogen at a flow rate of 140-160 mL / min at a rate of 2.5-3... Increase the temperature to 640-660℃ at a rate of 5℃ / min and hold for 40-50min. After reduction, purge with high-purity argon gas at a flow rate of 140-160mL / min for 8-12min. Then switch to a vacuum condition of 3-7Pa and increase the temperature to 990-1010℃ at a rate of 4.5-5.5℃ / min and hold for 15-25min. Finally, continue to increase the temperature to 1400-1410℃ at a rate of 4.5-5.5℃ / min and hold for 40-50min for sintering. Afterward, cool to 1200℃ at a rate of 5-7℃ / min and cool to room temperature with the furnace.

[0030] Preferably, the ratio of the surface-modified tungsten carbide powder, tantalum pentaethoxylate, tantalum oxalate aqueous solution, cobalt acetate tetrahydrate, and carbon black is 100g:0.42-0.56g:0.70-1.00g:42.0-46.0g:0.08-0.16g.

[0031] The present invention also provides a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance.

[0032] The beneficial effects of this invention are:

[0033] The high wear-resistant and anti-slip nail core preparation method provided by this invention effectively avoids the formation of coarse pool-like cobalt phase after sintering by constructing a modified interface in carbide powder through dopamine-acrylic acid copolymerization. This ensures that the binder phase layer is evenly distributed in the particle neck. This structure not only ensures the continuous transmission of impact energy but also reduces local brittle areas. Thus, it significantly enhances the resistance to micro-chipping without increasing the cobalt content, while maintaining excellent wear resistance.

[0034] This invention establishes a distinct spatial pre-designed structure on the surface of tungsten carbide by sequentially introducing pentaethoxytantalum and tantalum oxalate aqueous solutions. The synergistic effect produced by the introduction of the two tantalum sources in a strict order enables the anti-skid studs to improve both braking performance on ice and stability on wet roads.

[0035] Furthermore, this invention incorporates carbon black to regulate carbon balance during the cobalt precursor introduction step, avoiding localized decarburization caused by tantalum-oxygen precursor conversion and preventing the formation of the η-brittle phase. After sintering, the microstructure is dense, the tungsten carbide grains maintain their fine original size, and porosity and decarburization defects are controlled at a low level.

[0036] The anti-skid studs obtained by this invention have comprehensively improved the stud tip edge retention ability, the anti-micro-chipping performance of the particle contact neck area, and the grip stability of the entire tire on ice and wet roads under harsh working conditions of alternating impacts from ice, snow melt water, and exposed gravel. They are especially suitable for high-frequency start-stop scenarios such as passenger car snow tires and AGVs in cold chain parks. Detailed Implementation

[0037] 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.

[0038] Raw material source and model parameters:

[0039] Tungsten carbide powder: DS50, Fisher particle size 0.50-0.60 μm, maximum oxygen content 0.40%, maximum free carbon content 0.08%; tantalum pentaethoxylate: Merck Sigma-Aldrich, grade 339113, trace metal standard purity 99.98%; Tantalum oxalate aqueous solution: tantalum content 12%, clear water-based solution; Basic alumina: Sigma-Aldrich, grade 199443, Brockmann I activated basic alumina; Carbon black: Sigma-Aldrich, grade 940313, particle size 30-60 nm, specific surface area 250 m² / g. 2 / g; Paraffin: Sigma-Aldrich, grade 76244, is a white granular paraffin.

[0040] Example 1: A method for preparing a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, the specific steps of which are as follows:

[0041] S1: 100g of tungsten carbide powder was vacuum dried at 80℃ for 2h for later use; 0.72g of acrylic acid was passed through a glass short column packed with 20g of basic alumina in one pass, and the acrylic acid after removing the polymerization inhibitor was collected for later use within 15min; 100g of dried tungsten carbide powder was added to a mixed solvent of 105mL deionized water and 45mL anhydrous ethanol, stirred at 400rpm for 10min and sonicated for 10min, then 0.20g of glacial acetic acid and 0.70g of sodium acetate trihydrate were added, the pH of the system was adjusted to 5.0-5.4, air was bubbled in for 5min, then 0.24g of dopamine hydrochloride and 0.72g of acrylic acid treated with the polymerization inhibitor were added, stirred at 27℃ for 2h, then heated to 35℃ and continued to react for 1.0h, after the reaction was completed, filtered, and washed twice with anhydrous ethanol / deionized water mixture with a volume ratio of 80:20, and vacuum dried at 50℃ for 6h to obtain surface-modified tungsten carbide powder;

[0042] S2: Add 100g of surface-modified tungsten carbide powder to 180mL of anhydrous ethanol, and stir at 300rpm for 20min under dry nitrogen protection at a dew point of -40℃ to form a suspension. Dissolve 0.50g of pentaethoxytantalum in 20mL of anhydrous ethanol and add it dropwise to the above suspension within 15min, and continue stirring for 40min. Then, remove most of the solvent from the slurry under reduced pressure until it is in a uniform wet powder state. Then, spray 1.00g of aging solution prepared by 0.96g of anhydrous ethanol and 0.04g of deionized water by atomization. Aging is carried out in a sealed environment at 40℃ for 30min, and then vacuum dried at 50℃ for 2h.

[0043] S3: Add all the powder obtained in S2 to 30 mL of deionized water, stir at 250 rpm for 10 min, then add 0.85 g of tantalum oxalate aqueous solution and continue stirring for 20 min to keep the pH of the system at 2.5-4.0; filter, rinse once with deionized water, and vacuum dry at 60 °C for 4 h.

[0044] S4: Place all the powder obtained in S3 into a mixing container, add 44.0g of cobalt acetate tetrahydrate and 0.12g of carbon black into a mixed solvent consisting of 90mL of deionized water and 10mL of anhydrous ethanol, stir at 50℃ to completely dissolve the cobalt acetate tetrahydrate and uniformly disperse the carbon black, then add it to the powder in small amounts multiple times within 20min, then mix with a low-speed drum at 60rpm for 40min, and vacuum dry at 60℃ for 7-9h;

[0045] S5: Add 1.0g of paraffin to the dry powder obtained in S4, mix at 70℃ for 30min, cool and pass through a 90-110 mesh sieve to obtain shaped granules; press the obtained shaped granules into cylindrical anti-slip nail core blanks at 220MPa, wherein the diameter of the nail core blank is 2.2mm and the height is 4.5mm.

[0046] S6: Place all the nail core blanks obtained in S5 into a vacuum sintering furnace. First, under a vacuum of 500 Pa, heat the furnace to 120 °C at 2 °C / min and hold for 1 h to remove residual solvent. Then, heat the furnace to 280 °C at 1 °C / min and hold for 1 h to remove paraffin. Next, heat the furnace to 420 °C at 1 °C / min and hold for 1 h. Then, switch to high-purity hydrogen at a flow rate of 150 mL / min and heat the furnace to 650 °C at 3 °C / min and hold for 45 min. After reduction, purge the furnace with high-purity argon at a flow rate of 150 mL / min for 10 min. Then, switch to a vacuum of 5 Pa and heat the furnace to 1000 °C at 5 °C / min and hold for 20 min. Finally, continue to heat the furnace to 1405 °C at 5 °C / min and hold for 45 min for sintering. Afterward, cool the furnace to 1200 °C at 6 °C / min and cool it to room temperature to obtain high-density cemented carbide anti-slip nails.

[0047] Example 2: A method for preparing a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, the specific steps of which are as follows:

[0048] S1: First, vacuum dry 100g of tungsten carbide powder at 78℃ for 1.8h for later use; pass 0.60g of acrylic acid through a short glass column packed with 18g of basic alumina in one pass, collect the acrylic acid after removing the polymerization inhibitor for later use within 12min; add 100g of dried tungsten carbide powder to a mixed solvent of 100mL deionized water and 40mL anhydrous ethanol, stir at 350rpm for 8min and sonicate for 8min, then add 0.18g of ethylene glycol. The system was adjusted to pH 5.0-5.4 by adding acid and 0.60g sodium acetate trihydrate, and then air was bubbled in for 4 min. 0.20g dopamine hydrochloride and 0.60g acrylic acid treated with the polymerization inhibitor were added. The mixture was stirred at 25℃ for 1.8 h, and then heated to 33℃ to continue the reaction for 0.8 h. After the reaction was completed, the mixture was filtered and washed twice with anhydrous ethanol / deionized water mixture with a volume ratio of 80:20. The mixture was then vacuum dried at 48℃ for 5 h to obtain surface-modified tungsten carbide powder.

[0049] S2: Add 100g of surface-modified tungsten carbide powder to 170mL of anhydrous ethanol, and stir at 280rpm for 15min under dry nitrogen protection at a dew point of -45℃ to form a suspension. Dissolve 0.42g of pentaethoxytantalum in 18mL of anhydrous ethanol and add it dropwise to the above suspension within 12min, and continue stirring for 35min. Then, remove most of the solvent from the slurry under reduced pressure until it is in a uniform wet powder state. Then, spray 0.80g of aging solution prepared by 0.77g of anhydrous ethanol and 0.03g of deionized water in the slurry by atomization. Aging is carried out in a sealed environment at 35℃ for 25min, and then vacuum dried at 48℃ for 1.5h.

[0050] S3: Add all the powder obtained in S2 to 28 mL of deionized water, stir at 230 rpm for 8 min, then add 0.70 g of tantalum oxalate aqueous solution and continue stirring for 15 min to keep the pH of the system at 2.5-4.0; filter, rinse once with deionized water, and vacuum dry at 58 °C for 3.5 h.

[0051] S4: Place all the powder obtained in S3 into a mixing container, add 42.0g of cobalt acetate tetrahydrate and 0.08g of carbon black to a mixed solvent consisting of 85mL of deionized water and 8mL of anhydrous ethanol, stir at 48°C to completely dissolve the cobalt acetate tetrahydrate and uniformly disperse the carbon black, then add it to the powder in small amounts multiple times within 15min, then mix with a low-speed drum at 50rpm for 35min, and vacuum dry at 58°C for 7h;

[0052] S5: Add 0.9g of paraffin to the dry powder obtained in S4, mix at 68℃ for 25min, cool and pass through a 90-110 mesh sieve to obtain shaped granules; press the obtained shaped granules into cylindrical anti-slip nail core blanks at 210MPa, wherein the diameter of the nail core blank is 2.2mm and the height is 4.5mm.

[0053] S6: Place all the nail core blanks obtained in S5 into a vacuum sintering furnace. First, heat to 115℃ at a vacuum of 400Pa and hold for 0.8h at a rate of 1.5℃ / min to remove residual solvent; then heat to 270℃ at a rate of 0.8℃ / min and hold for 0.8h to remove paraffin; then heat to 410℃ at a rate of 0.8℃ / min and hold for 0.8h. Subsequently, switch to high-purity hydrogen gas at a flow rate of 140mL / min and heat at a rate of 2.5℃ / min. The temperature was raised to 640℃ and held for 40 min. After reduction, high-purity argon gas at a flow rate of 140 mL / min was introduced for 8 min to purge the metal. Then, the temperature was switched to a vacuum condition of 3 Pa and raised to 990℃ at a rate of 4.5℃ / min and held for 15 min. Finally, the temperature was raised to 1400℃ at a rate of 4.5℃ / min and held for 40 min for sintering. Afterward, the temperature was cooled to 1200℃ at a rate of 5℃ / min and then cooled to room temperature with the furnace to obtain a high-density cemented carbide anti-slip nail.

[0054] Example 3: A method for preparing a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, the specific steps of which are as follows:

[0055] S1: 100g of tungsten carbide powder was vacuum dried at 82℃ for 2.2h for later use; 0.84g of acrylic acid was passed through a short glass column packed with 22g of basic alumina in one pass, and the acrylic acid after removing the polymerization inhibitor was collected and used within 18min; 100g of dried tungsten carbide powder was added to a mixed solvent of 110mL deionized water and 50mL anhydrous ethanol, stirred at 450rpm for 12min and sonicated for 12min, and then 0.22g of ice was added. Acetic acid and 0.80 g sodium acetate trihydrate were mixed, and the pH of the system was adjusted to 5.0-5.4. After bubbling air for 6 min, 0.28 g dopamine hydrochloride and 0.84 g acrylic acid treated with the polymerization inhibitor were added. The mixture was stirred at 30 °C for 2.2 h, and then heated to 37 °C to continue the reaction for 1.2 h. After the reaction was completed, the mixture was filtered and washed twice with anhydrous ethanol / deionized water mixture with a volume ratio of 80:20. The mixture was then vacuum dried at 52 °C for 7 h to obtain surface-modified tungsten carbide powder.

[0056] S2: Add 100g of surface-modified tungsten carbide powder to 190mL of anhydrous ethanol, and stir at 320rpm for 25min under dry nitrogen protection at a dew point of -35℃ to form a suspension. Dissolve 0.56g of pentaethoxytantalum in 22mL of anhydrous ethanol and add it dropwise to the above suspension within 18min, and continue stirring for 45min. Then, remove most of the solvent from the slurry under reduced pressure until it is in a uniform wet powder state. Then, spray 1.10g of aging solution prepared by 1.05g of anhydrous ethanol and 0.05g of deionized water by atomization. Aging is carried out in a sealed environment at 45℃ for 35min, and then vacuum dried at 52℃ for 2.5h.

[0057] S3: Add all the powder obtained in S2 to 32 mL of deionized water, stir at 270 rpm for 12 min, then add 1.00 g of tantalum oxalate aqueous solution and continue stirring for 25 min to keep the pH of the system at 2.5-4.0; filter, rinse once with deionized water, and vacuum dry at 62 °C for 4.5 h.

[0058] S4: Place all the powder obtained in S3 into a mixing container, add 46.0 g of cobalt acetate tetrahydrate and 0.16 g of carbon black into a mixed solvent consisting of 95 mL of deionized water and 12 mL of anhydrous ethanol, stir at 52 °C to completely dissolve the cobalt acetate tetrahydrate and uniformly disperse the carbon black, then add it to the powder in small amounts multiple times within 25 min, then mix with a low-speed drum at 70 rpm for 45 min, and vacuum dry at 62 °C for 9 h;

[0059] S5: Add 1.1g of paraffin to the dry powder obtained in S4, mix at 72℃ for 35min, cool and pass through a 90-110 mesh sieve to obtain shaped granules; press the obtained shaped granules into cylindrical anti-slip nail core blanks at 230MPa, wherein the diameter of the nail core blank is 2.2mm and the height is 4.5mm.

[0060] S6: Place all the nail core blanks obtained in S5 into a vacuum sintering furnace. First, heat to 125℃ at a vacuum of 600Pa at a rate of 2.5℃ / min and hold for 1.2h to remove residual solvent; then heat to 290℃ at a rate of 1.2℃ / min and hold for 1.2h to remove paraffin; then heat to 430℃ at a rate of 1.2℃ / min and hold for 1.2h, then switch to high-purity hydrogen at a flow rate of 160mL / min and heat to 3.5℃ / min. The temperature was 660℃ and held for 50 min. After reduction, high-purity argon gas at a flow rate of 160 mL / min was introduced for 12 min to purge the metal. Then, the temperature was switched to a vacuum condition of 7 Pa, and the temperature was increased to 1010℃ at a rate of 5.5℃ / min and held for 25 min. Finally, the temperature was increased to 1410℃ at a rate of 5.5℃ / min and held for 50 min for sintering. Afterward, the temperature was cooled to 1200℃ at a rate of 7℃ / min and then cooled to room temperature in the furnace to obtain a high-density cemented carbide anti-slip nail.

[0061] Comparative Example 1: The difference from Example 1 is that in step S1, dopamine hydrochloride and acrylic acid are not added to modify the tungsten carbide powder. Instead, the tungsten carbide powder is added to a mixed solvent of deionized water and anhydrous ethanol. The other conditions are the same as in Example 1.

[0062] Comparative Example 2: The difference from Example 1 is that only pentaethoxytantalum is retained as a tantalum source. In step S2, 0.72g of pentaethoxytantalum (calculated according to the amount of tantalum element added) is dissolved in 20mL of anhydrous ethanol and added. In step S3, tantalum oxalate aqueous solution is no longer added. The powder obtained in step S2 is added to 30mL of deionized water, stirred for 20min, filtered and dried. The remaining conditions are the same as in Example 1.

[0063] Comparative Example 3: The difference from Example 1 is that only tantalum source, tantalum oxalate aqueous solution, is retained. In step S2, tantalum pentaethoxy is not added, and aging solution is not sprayed in for closed aging. In step S3, 2.69g of tantalum oxalate aqueous solution is added instead (calculated according to the amount of tantalum element added). The other conditions are the same as in Example 1.

[0064] Comparative Example 4: The difference from Example 1 is that the order of adding the two tantalum sources is reversed. That is, the powder obtained in step S1 is first added to 30 mL of deionized water and 0.83 g of tantalum oxalate aqueous solution is added according to the method in step S3. After filtration and drying, 0.50 g of pentaethoxytantalum is added to 180 mL of anhydrous ethanol according to the method in step S2 and aged. The other conditions are the same as in Example 1.

[0065] Comparative Example 5: The difference from Example 1 is that in step S2, after adding 0.50g of tantalum pentaethoxy and continuing to stir for 40min, the aging solution was not sprayed in for sealed aging, but instead the product was directly vacuum dried at 50°C for 2h; the other conditions were the same as in Example 1.

[0066] Comparative Example 6: The difference from Example 1 is that step S4 is performed before step S3; the other conditions are the same as in Example 1.

[0067] Comparative Example 7: The difference from Example 1 is that carbon black is not added in step S4, but an equal amount of tungsten carbide powder is added to make up the total amount of solids; the other conditions are the same as in Example 1.

[0068] Performance testing

[0069] The test samples were prepared according to the methods of the examples and comparative examples respectively. The mixed powders of the same batch were pressed and sintered simultaneously to form standard specimens: block specimens (10mm×10mm×5mm); the second type is rectangular transverse fracture strength specimens that meet the size requirements of GB / T 3851-2015; the wear test uses cylindrical pin specimens (Φ6mm×12mm) with the same composition as the anti-slip nail core and sintered in the same furnace.

[0070] The nail cores obtained from each embodiment and comparative example were pressed into the same batch of commercially available aluminum alloy nail sleeves using the same pressing equipment to produce finished anti-skid nails with consistent external dimensions. Then, 98 nails were pressed into the same batch of 205 / 55R16 winter passenger car tires at a height of 1.20mm±0.05mm per tire. The tires used should meet the requirements of GB 9743-2024 and should be indoor ground and pre-run-in in accordance with GB / T42359-2023 before the test.

[0071] Density test: The test was conducted in accordance with GB / T 3850-2015. Five samples from the examples and comparative examples were taken. The samples were dried at 105℃ for 1 hour and then cooled to room temperature. The density was determined in deionized water at 25℃ using the Archimedes water displacement method. The average value of the five parallel samples was taken as the result.

[0072] Rockwell A hardness test: Refer to GB / T 3849.1-2015. Take the samples obtained from the examples and comparative examples, polish the test surface to a mirror finish to ensure no obvious scratches and edge defects. Select at least 10 test points for each sample, with a spacing of not less than 1 mm between each test point and a distance of not less than 1 mm from the edge. Record the Rockwell A hardness and take the average value.

[0073] Transverse fracture strength test: Refer to GB / T 3851-2015. Take 5 specimens (rectangular transverse fracture strength specimens) from the example and comparative examples. Use a standard three-point bending fixture for testing. Set the loading speed according to GB / T 3851-2015. Record the fracture load and convert it into transverse fracture strength. The result is the average value of 5 specimens.

[0074] Coercivity test: The test was conducted in accordance with GB / T 3848-2017. Three samples were taken from each of the examples and comparative examples. The surface of the samples was cleaned with anhydrous ethanol and dried before the coercivity was measured.

[0075] Metallographic structure test: The samples obtained from the examples and comparative examples were cut, inlaid, ground and polished in sequence. The polishing endpoint was achieved by using a 1μm diamond suspension. The structure was observed using a metallographic microscope and a scanning electron microscope. Ten fields of view were randomly selected for each sample to determine the average tungsten carbide grain size.

[0076] Pin-disc friction and wear test: The test was conducted in accordance with YB / T 6178-2024. The test specimens (Φ6mm×12mm cylindrical pin specimens) obtained from the examples and comparative examples were used. The grinding disc was made of GCr15 bearing steel, with a hardness of 60HRC and a surface roughness Ra of 0.20μm±0.02μm. Before the test, the test specimens and the grinding disc were ultrasonically cleaned with anhydrous ethanol for 5min and then dried. The test load was set to 30N, the linear velocity was set to 0.20m / s, the total sliding distance was set to 1000m, the ambient temperature was controlled at 23℃, and the relative humidity was controlled at 50%. The test was conducted continuously under dry friction conditions.

[0077] Whole-tire ice grip performance test: Following GB / T 41327-2022, 98 pre-made anti-skid studs were installed on each tire, with an exposed height of 1.20mm ± 0.05mm, on the same batch of 205 / 55R16 winter passenger car tires. Indoor grinding and pre-break-in were performed according to GB / T 42359-2023. Test vehicles equipped with anti-lock braking systems (ABS) were used, with tire inflation pressure set at 220kPa, ambient temperature controlled at -15℃, and ice surface temperature controlled at -12℃. The test vehicle entered the test area in a straight line at a speed of at least 25km / h. After entering the area, the vehicle was put into neutral, and a stable braking force was quickly applied to activate the vehicle's ABS. The average deceleration between 20km / h and 5km / h was automatically collected. Each sample group underwent at least 9 valid tests, and the maximum and minimum values ​​were discarded before averaging.

[0078] Whole tire wet road relative grip performance test: The test was conducted in accordance with GB / T 21910-2017, using the same batch, specifications, and pressing scheme as the tires used in the ice grip performance test. The tires were ground indoors according to GB / T 42359-2023. Test vehicles equipped with anti-lock braking systems were used, and the tire inflation pressure was set to 220 kPa. The single-wheel test load was set at 75% of the tire load capacity. After the test tires were left to stand at the test site for 2 hours, they underwent two pre-break-in cycles. The test vehicle entered the wet road test area at 85 km / h, and after entering the area, it was put into neutral and braked at full force until data acquisition was completed. The water spraying, water film control, standard test tire insertion sequence, and data processing of the test road surface were all performed in accordance with GB / T 21910-2017. Each sample group underwent at least 9 valid tests. After discarding the maximum and minimum values, the average deceleration was calculated.

[0079] The test results are shown in Table 1.

[0080] Table 1 Performance Test Results

[0081] <![CDATA[Density (g / cm 3 )]]> Rockwell A hardness (HRA) Transverse fracture strength (MPa) Coercive force (kA / m) Average tungsten carbide grain size (μm) <![CDATA[Wear volume (mm 3 )]]> <![CDATA[Average deceleration on ice (m / s 2 )]]> <![CDATA[Average deceleration on wet road surface (m / s 2 )]]> Example 1 14.55 91.9 3920 32.6 0.50 0.026 3.64 6.93 Example 2 14.57 91.9 3980 33.4 0.48 0.027 3.61 6.98 Example 3 14.54 91.8 3870 31.9 0.53 0.028 3.56 6.90 Comparative Example 1 14.53 91.7 3830 31.4 0.54 0.029 3.52 6.86 Comparative Example 2 14.48 90.8 3460 25.8 0.73 0.044 3.08 6.54 Comparative Example 3 14.52 91.4 3580 29.7 0.60 0.034 3.34 6.62 Comparative Example 4 14.51 91.1 3650 28.9 0.64 0.039 3.20 6.68 Comparative Example 5 14.50 91.0 3520 27.8 0.67 0.041 3.16 6.58 Comparative Example 6 14.52 91.3 3620 29.1 0.62 0.037 3.27 6.65 Comparative Example 7 14.51 91.0 3410 27.4 0.66 0.040 3.18 6.56

[0082] Data Analysis: As can be seen from the data in Table 1, the cemented carbide anti-skid studs prepared according to this invention maintain a good balance between density, Rockwell A hardness, transverse fracture strength, coercive force, average tungsten carbide grain size, pin-disc friction wear, and overall tire grip performance. On the one hand, it inhibits abnormal tungsten carbide growth, delaying the rounding of the stud tip under alternating impacts from ice and exposed gravel; on the other hand, it avoids the formation of coarse, pool-like binder phases after sintering, reducing micro-chipping and localized brittleness, which helps extend the effective grip time of the anti-skid studs, while also considering braking on ice, stability on snowmelt roads, and impact durability against exposed gravel.

[0083] As can be seen from the data in Example 1 and Comparative Example 1 in Table 1, without the construction of a surface modification layer, density, Rockwell A hardness, transverse fracture strength, coercivity, wear resistance, and overall tire grip performance on ice and wet surfaces all decreased simultaneously, and the average tungsten carbide grain size increased. The main reason for this is that the lack of differentiated adsorption sites formed by dopamine hydrochloride and acrylic acid on the tungsten carbide surface means that subsequent deposition of tantalum pentaethoxylate, tantalum oxalate aqueous solution, and cobalt acetate tetrahydrate can only occur in a more random manner, making it difficult to form a well-defined microstructure at the nail tip edges and particle contact necks. Ultimately, this makes the nail tips easier to round and the binder phase in the particle contact necks easier to coarsen.

[0084] As can be seen from the data in Example 1 and Comparative Examples 2 and 3 in Table 1, after introducing two tantalum sources at the same time, the present invention not only did not show the result of one increasing while the other decreases when used alone, but also improved wear resistance, resistance to micro-chipping, and comprehensive grip on icy and wet roads at the same time. A significant synergistic effect was established through the sequence of introduction, presenting a comprehensive effect that is difficult to expect directly from a single tantalum source.

[0085] As can be seen from the data in Example 1 and Comparative Example 4 in Table 1, under the premise that the total amount of the two tantalum sources remains unchanged, simply reversing the order of introduction of tantalum oxalate aqueous solution and pentaethoxytantalum results in a significant drop in overall performance. The main reason is that after the tantalum oxalate aqueous solution enters the system first, it preferentially occupies some sites that should have been directionally recognized by pentaethoxytantalum. When pentaethoxytantalum is added subsequently, it is difficult to fully utilize the catechol-enriched sites to achieve edge-priority occupancy, thus disrupting the hierarchical relationship of first occupancy, then curing, and then filling.

[0086] As can be seen from the data in Table 1 for Example 1 and Comparative Example 5, even when the two tantalum source types and their order of addition remain unchanged, the overall performance still shows a significant decline after removing the aging step following the removal of pentaethoxytantalum. This indicates that after pentaethoxytantalum is first directionally anchored in anhydrous ethanol, it must still be fixed through restricted hydrolysis.

[0087] As can be seen from the data of Example 1 and Comparative Example 6 in Table 1, when cobalt acetate tetrahydrate is added before the tantalum oxalate aqueous solution, the Rockwell A hardness does not change drastically, but the transverse fracture strength, wear resistance and overall tire grip performance are significantly deteriorated. This indicates that the problem is not mainly due to the total amount of hard phase, but rather to the timing of the binder phase entering the system.

[0088] As can be seen from the data of Example 1 and Comparative Example 7 in Table 1, carbon black is not a common filler in this invention, but is used to compensate for the carbon loss during the conversion of oxygen and tantalum oxide precursor on the surface of tungsten carbide, so that the microstructure after sintering is maintained in a state more suitable for anti-slip nail applications.

[0089] 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, S 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 the details for the sake of brevity.

Claims

1. A method for preparing a cemented carbide anti-slip stud with high wear resistance and excellent anti-slip performance, characterized in that, Includes the following steps: S1: Tungsten carbide powder is subjected to an oxidative copolymerization reaction in a weakly acidic aerobic buffer solution containing dopamine hydrochloride and acrylic acid to obtain modified tungsten carbide powder. S2: Surface-modified tungsten carbide powder is dispersed in anhydrous ethanol, and tantalum pentaethoxy is added under dry nitrogen protection. After stirring, aging liquid is sprayed into the reaction system for sealed aging. After drying, it is ready for use. S3: Disperse the powder obtained in S2 in deionized water, add tantalum oxalate aqueous solution and continue stirring, then dry for later use; S4: Cobalt acetate tetrahydrate and carbon black are dispersed in a mixed solvent, mixed and then sprayed onto the powder obtained in S3. After mixing and drying, the mixture is ready for use. S5: Add paraffin wax to the powder obtained in S4, mix and granulate, and press into nail core blanks; S6: Sinter the blank obtained in S5 to obtain cemented carbide anti-slip nails; The ratio of the surface-modified tungsten carbide powder, tantalum pentaethoxylate, tantalum oxalate aqueous solution, cobalt acetate tetrahydrate, and carbon black is 100g:0.42-0.56g:0.70-1.00g:42.0-46.0g:0.08-0.16g.

2. The preparation method according to claim 1, characterized in that, The weight ratio of tungsten carbide powder, dopamine hydrochloride, and acrylic acid in step S1 is 100g:0.20-0.28g:0.60-0.84g.

3. The preparation method according to claim 1, characterized in that, The copolymerization reaction described in step S1 is to first stir at 25-30℃ for 1.8-2.2h, and then raise the temperature to 33-37℃ to continue the reaction for 0.8-1.2h.

4. The preparation method according to claim 1, characterized in that, In step S2, the surface-modified tungsten carbide powder weighs 100g, and the amount of aging solution injected is 0.80-1.10g.

5. The preparation method according to claim 1, characterized in that, The sealing aging temperature in step S2 is 35-45℃, and the time is 25-35 min.

6. The preparation method according to claim 1, characterized in that, The mixing speed in step S4 is 50-70 rpm, and the mixing time is 35-45 min.

7. The preparation method according to claim 1, characterized in that, In step S5, the amount of paraffin added is 0.9-1.1g, based on the weight of 100g of powder obtained in S4.

8. The preparation method according to claim 1, characterized in that, The specific sintering process described in step S6 is as follows: First, under a vacuum of 400-600 Pa, the temperature is increased to 115-125℃ at a rate of 1.5-2.5℃ / min and held for 0.8-1.2 h to remove residual solvent; then, the temperature is increased to 270-290℃ at a rate of 0.8-1.2℃ / min and held for 0.8-1.2 h to remove paraffin; then, the temperature is increased to 410-430℃ at a rate of 0.8-1.2℃ / min and held for 0.8-1.2 h, followed by switching to high-purity hydrogen gas at a flow rate of 140-160 mL / min and sintering at 2.5-3.5℃. Increase the temperature at 4.5-5.5℃ / min to 640-660℃ and hold for 40-50 min. After reduction, purge with high-purity argon gas at a flow rate of 140-160 mL / min for 8-12 min. Then switch to a vacuum condition of 3-7 Pa and increase the temperature at 4.5-5.5℃ / min to 990-1010℃ and hold for 15-25 min. Finally, continue to increase the temperature at 4.5-5.5℃ / min to 1400-1410℃ and hold for 40-50 min for sintering. Afterward, cool to 1200℃ at 5-7℃ / min and cool to room temperature with the furnace.

9. A type of hard alloy anti-slip stud with high wear resistance and excellent anti-slip performance, characterized in that, It is prepared according to any one of claims 1-8.