Super-hard alloy with high toughness and impact resistance for ground mining

Abstract

The present application relates to the technical field of hard alloy, in particular to a high-strength and high-toughness impact-resistant super coarse hard alloy for mining, which is based on an iron-nickel base, cooperates with a carbon nanotube-regulated carbon fiber agent and a boron agent to improve the bending strength, impact toughness, fatigue resistance and corrosion resistance stability of the super coarse hard alloy in acid, alkali and salt mist environments, and solves the problems of brittle fracture, poor corrosion resistance and short service life of traditional hard alloys in mining working conditions. The alloy prepared by the present application has high hardness, high strength and toughness and excellent corrosion resistance, and is suitable for strong impact and heavy load components such as mining drill bits, cutting teeth and drill bits.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, specifically to a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining applications. Background Technology

[0002] Mining equipment is subjected to harsh conditions such as high impact, high wear, and acid and alkali corrosion over long periods, requiring cemented carbide to possess high hardness, high strength and toughness, and good corrosion resistance. Ultra-coarse-grained cemented carbide, due to its large grain size and excellent impact resistance, has become the preferred material for core components such as drill bits, cutting teeth, and chisel bits. Traditional ultra-coarse-grained cemented carbides mostly use cobalt-based binders, which are costly, resource-scarce, and prone to corrosion in acid / alkali / salt spray environments, leading to grain boundary weakening, decreased toughness, and early brittle fracture failure. Furthermore, simply optimizing the binder phase is insufficient to simultaneously improve strength, toughness, and corrosion resistance.

[0003] Iron-nickel based materials, as binder phases, offer adjustable toughness and corrosion resistance, but suffer from weak interfacial bonding and insufficient grain control, making them unsuitable for meeting the high-impact requirements of mining operations. Carbon nanotubes and carbon fibers possess ultra-high strength and modulus, making them suitable for toughening and reinforcement, but they are prone to agglomeration and have poor wettability with the matrix. Boron can strengthen grain boundaries and improve corrosion resistance, but uneven dispersion can easily lead to the formation of a brittle phase. Therefore, this invention provides an ultra-coarse hard alloy with an iron-nickel based matrix, synergistically modified with carbon nanotube-modified carbon fiber agents and boron agents, addressing the problems of insufficient toughness, poor corrosion resistance, weak interfacial bonding, and short lifespan found in existing technologies. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining, so as to solve the problems mentioned in the background art.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] This invention provides a high-strength, high-toughness, and impact-resistant ultra-coarse cemented carbide for mining, comprising the following raw materials in parts by weight: 65-75 parts of ultra-coarse tungsten carbide powder, 15-25 parts of iron-nickel-based binder, 5-9 parts of carbon nanotube-modified carbon fiber agent, 3-6 parts of boron agent, and 1-3 parts of molding agent.

[0007] Preferably, the weight ratio of iron to nickel in the iron-nickel base is (2-3):1; the average particle size of the ultra-coarse tungsten carbide powder is 5-8 μm; and the molding agent is one or more combinations of paraffin wax, polyvinyl alcohol, and stearic acid.

[0008] Preferably, the method for preparing the carbon nanotube-modified carbon fiber agent is as follows:

[0009] S1, place carbon nanotubes in a first additive 3 to 5 times their total volume and sonicate them with an ultrasonic power of 350 to 400 W for 1 hour to obtain the first additive carbon nanotube liquid.

[0010] The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of (11-15):5 to obtain the carbon nanotube liquid.

[0011] S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol, and silane coupling agent KH550 are stirred evenly in a weight ratio of (1-3):5:(1-2) to obtain tannic acid solution; tannic acid solution, nano titanium dioxide, and carbon fiber are mixed in a weight ratio of (5-8):(3-5):2, filtered and dried to obtain carbon fiber functional agent.

[0012] S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of (8-11):3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

[0013] Preferably, the preparation method of the first admixture is as follows:

[0014] Mix 1-2 parts of Ce powder, 2-3 parts of 3-5% cobalt nitrate solution, and 1-2 parts of chromium powder evenly, then add 1-2 parts of hexamethylenetetramine and 2-4 parts of lanthanum chloride solution and mix thoroughly to obtain the first additive.

[0015] Preferably, the second additive is prepared by mixing molybdenum powder, nano-alumina, and tantalum carbide in a weight ratio of (1-2):(3-5):1 and sintering at 300-350°C for 1 hour to obtain the second additive.

[0016] Preferably, the lanthanum chloride solution has a mass fraction of 2-4%.

[0017] The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10–20 nm and a length of 10–30 μm.

[0018] The carbon fiber is short-cut carbon fiber with a length of 50–200 μm and a diameter of 6–8 μm; the nano-titanium dioxide has a particle size of 20–50 nm and a crystal form of anatase.

[0019] Ce powder has a particle size of 100–200 nm; the chromium powder has a particle size of 1–3 μm.

[0020] The molybdenum powder has a particle size of 1–3 μm; the nano-alumina has a particle size of 20–40 nm; and the tantalum carbide has a particle size of 1–5 μm.

[0021] Preferably, the method for preparing the boronizing agent is as follows:

[0022] S11, mix 2-4 parts of nano silica sol, 5-8 parts of sodium alginate solution with a mass fraction of 4-7% and 1-2 parts of silane coupling agent KH550 evenly to obtain a gel liquid;

[0023] S12: Place boron oxide in a sodium citrate solution with a mass fraction of 8-12% and a total volume of 3-5 times the boron oxide and stir until homogeneous. Then add nano diamond powder with a total boron oxide content of 5-7% and a gel liquid with a total boron oxide content of 4-6%. Stir at 55-60℃ and 450-500 r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

[0024] Preferably, the boron oxide has a particle size of 1–3 μm; the nanodiamond powder has a particle size of 30–80 nm.

[0025] Preferably, the preparation steps of the ultra-coarse cemented carbide are as follows:

[0026] Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is (4-6):1, and the ball milling time is 24-36 hours to obtain a mixture.

[0027] Step 2: Vacuum dry the mixture and pass it through a 100-200 mesh sieve to obtain spray-granulated powder;

[0028] Step 3: The granulated powder is cold-pressed under a pressure of 150-200 MPa to obtain a pressed compact;

[0029] Step 4: Vacuum sintering of the compact, heating to 400-500℃ to remove the forming agent, then heating at 10℃ / min to 1380-1450℃, holding for 1-2 hours, and cooling with the furnace to obtain a high-strength, tough, impact-resistant ultra-coarse cemented carbide for mining.

[0030] Preferably, in step one, the wet grinding medium is anhydrous ethanol with a solid-liquid ratio of 1:(2-3), in step two, the vacuum drying temperature is 70-90℃ and the drying time is 6-10h, and in step four, the vacuum degree is ≤5Pa.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention uses ultra-coarse tungsten carbide powder as the matrix and iron-nickel-based material as the binder phase. A stable austenitic solid solution is formed through Fe / Ni ratio optimization, improving plasticity and toughness, widening the carbon window, and inhibiting η-phase formation. Carbon nanotube-modified carbon fiber agents and boron agents work synergistically to toughen and reinforce, optimize interfaces, strengthen grain boundaries, and stabilize corrosion resistance, achieving a synergistic improvement in hardness, strength, toughness, and corrosion resistance. In the preparation of the carbon nanotube-modified carbon fiber agent, the first modifier uses Ce, Co, and La rare earth elements and metal elements to activate carbon nanotubes, improving dispersibility and interfacial wetting. The second modifier contains molybdenum, tantalum carbide, and nano-alumina to enhance high-temperature stability and hardness. The carbon fibers are modified with tannic acid, KH550, and nano-titanium dioxide, resulting in a strong bond with the matrix, forming a trans-grain boundary toughening network that inhibits crack propagation. The colloid liquid in the boron agent improves dispersion uniformity, boron oxide strengthens grain boundaries and enhances corrosion resistance, nano-diamonds improve hardness and wear resistance, and sodium citrate improves wettability and prevents agglomeration and brittle phase formation. Detailed Implementation

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

[0034] This embodiment of a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining comprises the following raw materials in parts by weight: 65-75 parts of ultra-coarse tungsten carbide powder, 15-25 parts of iron-nickel-based binder, 5-9 parts of carbon nanotube-modified carbon fiber agent, 3-6 parts of boron agent, and 1-3 parts of molding agent.

[0035] In this embodiment, the weight ratio of iron to nickel in the iron-nickel base is (2-3):1; the average particle size of the ultra-coarse tungsten carbide powder is 5-8 μm; and the molding agent is one or more combinations of paraffin wax, polyvinyl alcohol, and stearic acid.

[0036] The method for preparing carbon nanotube-modified carbon fiber agent in this embodiment is as follows:

[0037] S1, place carbon nanotubes in a first additive 3 to 5 times their total volume and sonicate them with an ultrasonic power of 350 to 400 W for 1 hour to obtain the first additive carbon nanotube liquid.

[0038] The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of (11-15):5 to obtain the carbon nanotube liquid.

[0039] S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol, and silane coupling agent KH550 are stirred evenly in a weight ratio of (1-3):5:(1-2) to obtain tannic acid solution; tannic acid solution, nano titanium dioxide, and carbon fiber are mixed in a weight ratio of (5-8):(3-5):2, filtered and dried to obtain carbon fiber functional agent.

[0040] S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of (8-11):3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

[0041] The preparation method of the first admixture in this embodiment is as follows:

[0042] Mix 1-2 parts of Ce powder, 2-3 parts of 3-5% cobalt nitrate solution, and 1-2 parts of chromium powder evenly, then add 1-2 parts of hexamethylenetetramine and 2-4 parts of lanthanum chloride solution and mix thoroughly to obtain the first additive.

[0043] The preparation method of the second additive in this embodiment is as follows: molybdenum powder, nano alumina and tantalum carbide are mixed in a weight ratio of (1-2):(3-5):1 and sintered at 300-350°C for 1 hour to obtain the second additive.

[0044] The mass fraction of the lanthanum chloride solution in this embodiment is 2-4%;

[0045] The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10–20 nm and a length of 10–30 μm.

[0046] The carbon fiber is short-cut carbon fiber with a length of 50–200 μm and a diameter of 6–8 μm; the nano-titanium dioxide has a particle size of 20–50 nm and a crystal form of anatase.

[0047] Ce powder has a particle size of 100–200 nm; the chromium powder has a particle size of 1–3 μm.

[0048] The molybdenum powder has a particle size of 1–3 μm; the nano-alumina has a particle size of 20–40 nm; and the tantalum carbide has a particle size of 1–5 μm.

[0049] The method for preparing the boron-containing agent in this embodiment is as follows:

[0050] S11, mix 2-4 parts of nano silica sol, 5-8 parts of sodium alginate solution with a mass fraction of 4-7% and 1-2 parts of silane coupling agent KH550 evenly to obtain a gel liquid;

[0051] S12: Place boron oxide in a sodium citrate solution with a mass fraction of 8-12% and a total volume of 3-5 times the boron oxide and stir until homogeneous. Then add nano diamond powder with a total boron oxide content of 5-7% and a gel liquid with a total boron oxide content of 4-6%. Stir at 55-60℃ and 450-500 r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

[0052] In this embodiment, the boron oxide particle size is 1-3 μm; the nanodiamond powder particle size is 30-80 nm.

[0053] The preparation steps of the ultra-coarse cemented carbide in this embodiment are as follows:

[0054] Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is (4-6):1, and the ball milling time is 24-36 hours to obtain a mixture.

[0055] Step 2: Vacuum dry the mixture and pass it through a 100-200 mesh sieve to obtain spray-granulated powder;

[0056] Step 3: The granulated powder is cold-pressed under a pressure of 150-200 MPa to obtain a pressed compact;

[0057] Step 4: Vacuum sintering of the compact, heating to 400-500℃ to remove the forming agent, then heating at 10℃ / min to 1380-1450℃, holding for 1-2 hours, and cooling with the furnace to obtain a high-strength, tough, impact-resistant ultra-coarse cemented carbide for mining.

[0058] In this embodiment, the wet grinding medium in step one is anhydrous ethanol with a solid-liquid ratio of 1:(2-3), the vacuum drying temperature in step two is 70-90℃, the drying time is 6-10h, and the vacuum degree in step four is ≤5Pa.

[0059] Example 1.

[0060] This embodiment of a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining includes the following raw materials in parts by weight: 65 parts ultra-coarse tungsten carbide powder, 15 parts iron-nickel-based binder, 5 parts carbon nanotube-modified carbon fiber agent, 3 parts boron agent, and 1 part forming agent.

[0061] In this embodiment, the weight ratio of iron to nickel in the iron-nickel base is 2:1; the average particle size of the ultra-coarse tungsten carbide powder is 5 μm; and the forming agent is paraffin wax.

[0062] The method for preparing carbon nanotube-modified carbon fiber agent in this embodiment is as follows:

[0063] S1, the carbon nanotubes are placed in a first additive in a volume of 3 times their total volume and ultrasonically treated with an ultrasonic power of 350W for 1 hour to obtain the first carbon nanotube liquid.

[0064] The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of 11:5 to obtain the carbon nanotube liquid.

[0065] S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol and silane coupling agent KH550 are stirred evenly in a weight ratio of 1:5:1 to obtain tannic acid solution; tannic acid solution, nano titanium dioxide and carbon fiber are mixed in a weight ratio of 5:3:2, filtered and dried to obtain carbon fiber functional agent.

[0066] S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of 8:3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

[0067] The preparation method of the first admixture in this embodiment is as follows:

[0068] Mix 1 part Ce powder, 2 parts 3% cobalt nitrate solution and 1 part chromium powder evenly, then add 1 part hexamethylenetetramine and 2 parts lanthanum chloride solution and mix thoroughly to obtain the first additive.

[0069] The preparation method of the second additive in this embodiment is as follows: molybdenum powder, nano-alumina and tantalum carbide are mixed in a weight ratio of 1:3:1 and sintered at 300°C for 1 hour to obtain the second additive.

[0070] The mass fraction of the lanthanum chloride solution in this embodiment is 2%.

[0071] The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10 nm and a length of 10 μm.

[0072] The carbon fiber is a short-cut carbon fiber with a length of 50 μm and a diameter of 6 μm; the nano-titanium dioxide has a particle size of 20 nm and a crystal form of anatase.

[0073] Ce powder has a particle size of 100 nm; the chromium powder has a particle size of 1 μm.

[0074] The molybdenum powder has a particle size of 1 μm; the nano-alumina has a particle size of 20 nm; and the tantalum carbide has a particle size of 1 μm.

[0075] The method for preparing the boron-containing agent in this embodiment is as follows:

[0076] S11, mix 2 parts of nano silica sol, 5 parts of 4% sodium alginate solution by mass fraction and 1 part of silane coupling agent KH550 evenly to obtain a gel liquid;

[0077] S12: Place boron oxide in a sodium citrate solution with a mass fraction of 8% (3 times its total volume) and stir until homogeneous. Then add nano diamond powder (5% of total boron oxide) and gel liquid (4% of total boron oxide). Stir at 55℃ and 450r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

[0078] In this embodiment, the boron oxide particle size is 1 μm; the nanodiamond powder particle size is 30 nm.

[0079] The preparation steps of the ultra-coarse cemented carbide in this embodiment are as follows:

[0080] Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is 4:1, and the ball milling time is 24 hours to obtain a mixture.

[0081] Step 2: Vacuum dry the mixture and pass it through a 100-mesh sieve to obtain spray-granulated powder;

[0082] Step 3: The granulated powder is cold-pressed under a pressure of 150 MPa to obtain a pressed compact;

[0083] Step 4: Vacuum sintering of the compact, heating to 400℃ to remove the forming agent, then heating to 1380℃ at 10℃ / min, holding for 1 hour, and cooling with the furnace to obtain a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining.

[0084] In this embodiment, the wet grinding medium in step one is anhydrous ethanol with a solid-liquid ratio of 1:2; the vacuum drying temperature in step two is 70°C and the drying time is 6 hours; and the vacuum degree in step four is ≤5Pa.

[0085] Example 2.

[0086] This embodiment of a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining includes the following raw materials in parts by weight: 75 parts ultra-coarse tungsten carbide powder, 25 parts iron-nickel-based binder, 9 parts carbon nanotube-modified carbon fiber agent, 6 parts boron agent, and 3 parts forming agent.

[0087] In this embodiment, the weight ratio of iron to nickel in the iron-nickel base is 3:1; the average particle size of the ultra-coarse tungsten carbide powder is 8 μm; and the molding agent is polyvinyl alcohol.

[0088] The method for preparing carbon nanotube-modified carbon fiber agent in this embodiment is as follows:

[0089] S1, the carbon nanotubes are placed in a first additive 5 times their total volume and ultrasonically treated with an ultrasonic power of 400W for 1 hour to obtain the first carbon nanotube liquid.

[0090] The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of 15:5 to obtain the carbon nanotube liquid.

[0091] S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol and silane coupling agent KH550 are stirred evenly in a weight ratio of 3:5:2 to obtain tannic acid solution; tannic acid solution, nano titanium dioxide and carbon fiber are mixed in a weight ratio of 8:5:2, filtered and dried to obtain carbon fiber functional agent.

[0092] S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of 11:3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

[0093] The preparation method of the first admixture in this embodiment is as follows:

[0094] Two parts of Ce powder, three parts of 5% cobalt nitrate solution, and two parts of chromium powder were mixed evenly. Then, two parts of hexamethylenetetramine and four parts of lanthanum chloride solution were added and mixed thoroughly to obtain the first additive.

[0095] The preparation method of the second additive in this embodiment is as follows: molybdenum powder, nano-alumina and tantalum carbide are mixed in a weight ratio of 2:5:1 and sintered at 350°C for 1 hour to obtain the second additive.

[0096] The mass fraction of the lanthanum chloride solution in this embodiment is 4%.

[0097] The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 20 nm and a length of 30 μm.

[0098] The carbon fiber is a short-cut carbon fiber with a length of 200 μm and a diameter of 8 μm; the nano-titanium dioxide has a particle size of 50 nm and a crystal form of anatase.

[0099] Ce powder has a particle size of 200 nm; the chromium powder has a particle size of 3 μm.

[0100] The molybdenum powder has a particle size of 3 μm; the nano-alumina has a particle size of 40 nm; and the tantalum carbide has a particle size of 5 μm.

[0101] The method for preparing the boron-containing agent in this embodiment is as follows:

[0102] S11, mix 4 parts of nano silica sol, 8 parts of 7% sodium alginate solution and 2 parts of silane coupling agent KH550 evenly to obtain a gel liquid;

[0103] S12: Place boron oxide in a 5-fold (5 times its total weight) sodium citrate solution and stir until homogeneous. Then add 7% (7% total boron oxide) nano-diamond powder and 6% (6% total boron oxide) gel liquid. Stir at 60°C and 500 r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

[0104] In this embodiment, the boron oxide particle size is 3μm; the nanodiamond powder particle size is 80nm.

[0105] The preparation steps of the ultra-coarse cemented carbide in this embodiment are as follows:

[0106] Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is 6:1, and the ball milling time is 36 hours to obtain a mixture.

[0107] Step 2: Vacuum dry the mixture and pass it through a 200-mesh sieve to obtain spray-granulated powder;

[0108] Step 3: The granulated powder is cold-pressed under a pressure of 200 MPa to obtain a pressed compact;

[0109] Step 4: Vacuum sintering of the compact, heating to 500℃ to remove the forming agent, then heating to 1450℃ at 10℃ / min, holding for 2 hours, and cooling with the furnace to obtain a high-strength, tough, impact-resistant ultra-coarse cemented carbide for mining.

[0110] In this embodiment, the wet grinding medium in step one is anhydrous ethanol with a solid-liquid ratio of 1:3; the vacuum drying temperature in step two is 90°C and the drying time is 10 hours; and the vacuum degree in step four is ≤5Pa.

[0111] Example 3.

[0112] This embodiment of a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining comprises the following raw materials in parts by weight: 70 parts ultra-coarse tungsten carbide powder, 20 parts iron-nickel-based binder, 7 parts carbon nanotube-modified carbon fiber agent, 4.5 parts boron agent, and 2 parts forming agent.

[0113] In this embodiment, the iron-nickel base has an iron to nickel weight ratio of 2.5:1; the ultra-coarse tungsten carbide powder has an average particle size of 6.5 μm; and the forming agent is stearic acid.

[0114] The method for preparing carbon nanotube-modified carbon fiber agent in this embodiment is as follows:

[0115] S1, the carbon nanotubes are placed in a first additive in four times their total volume and ultrasonically treated with an ultrasonic power of 375W for 1 hour to obtain the first carbon nanotube liquid.

[0116] The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of 13:5 to obtain the carbon nanotube liquid.

[0117] S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol, and silane coupling agent KH550 are stirred evenly in a weight ratio of 2:5:1.5 to obtain tannic acid solution; tannic acid solution, nano titanium dioxide, and carbon fiber are mixed in a weight ratio of 6.5:4:2, filtered, and dried to obtain carbon fiber functional agent.

[0118] S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of 9:3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

[0119] The preparation method of the first admixture in this embodiment is as follows:

[0120] Mix 1.5 parts Ce powder, 2.5 parts 4% cobalt nitrate solution, and 1.5 parts chromium powder evenly, then add 1.5 parts hexamethylenetetramine and 3 parts lanthanum chloride solution and mix thoroughly to obtain the first additive.

[0121] The preparation method of the second additive in this embodiment is as follows: molybdenum powder, nano-alumina and tantalum carbide are mixed in a weight ratio of 1.5:4:1 and sintered at 325°C for 1 hour to obtain the second additive.

[0122] The mass fraction of the lanthanum chloride solution in this embodiment is 3%.

[0123] The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 15 nm and a length of 20 μm.

[0124] The carbon fiber is a short-cut carbon fiber with a length of 100 μm and a diameter of 7 μm; the nano-titanium dioxide has a particle size of 35 nm and a crystal form of anatase.

[0125] Ce powder has a particle size of 150 nm; the chromium powder has a particle size of 2 μm.

[0126] The molybdenum powder has a particle size of 2 μm; the nano-alumina has a particle size of 30 nm; and the tantalum carbide has a particle size of 3 μm.

[0127] The method for preparing the boron-containing agent in this embodiment is as follows:

[0128] S11, mix 3 parts of nano silica sol, 6.5 parts of 5.5% sodium alginate solution and 1.5 parts of silane coupling agent KH550 evenly to obtain a gel liquid;

[0129] S12: Place boron oxide in a 10% sodium citrate solution (4 times its total volume) and stir until homogeneous. Then add 6% nano-diamond powder and 5% gel liquid (6% boron oxide total volume). Stir at 58℃ and 470r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

[0130] In this embodiment, the boron oxide particle size is 2 μm; the nanodiamond powder particle size is 55 nm.

[0131] The preparation steps of the ultra-coarse cemented carbide in this embodiment are as follows:

[0132] Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is 5:1, and the ball milling time is 28 hours to obtain a mixture.

[0133] Step 2: Vacuum dry the mixture and pass it through a 100-mesh sieve to obtain spray-granulated powder;

[0134] Step 3: The granulated powder is cold-pressed under a pressure of 175 MPa to obtain a compact;

[0135] Step 4: Vacuum sintering of the compact, heating to 450℃ to remove the forming agent, then heating to 1410℃ at 10℃ / min, holding for 1.5h, and cooling with the furnace to obtain a high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining.

[0136] In this embodiment, the wet grinding medium in step one is anhydrous ethanol with a solid-liquid ratio of 1:2.5, the vacuum drying temperature in step two is 80°C and the drying time is 8 hours, and the vacuum degree in step four is ≤5Pa.

[0137] Comparative setup (changing only a single variable compared to Example 3)

[0138] Comparative Example 1: Carbon fiber agent without carbon nanotube modulation;

[0139] Comparative Example 2: No carbon fiber functional agents were added during the preparation of carbon nanotube-modified carbon fiber agents;

[0140] Comparative Example 3: Tannic acid solution was not used in the preparation of carbon fiber functional agents;

[0141] Comparative Example 4: No second additive was added during the preparation of the carbon nanotube liquid;

[0142] Comparative Example 5: No Ce powder or chromium powder was added during the preparation of the first additive;

[0143] Comparative Example 6: No cobalt nitrate solution was added during the preparation of the first additive;

[0144] Comparative Example 7: No boron agent added;

[0145] Comparative Example 8: No adhesive liquid was added during the preparation of the boronizing agent.

[0146] Test methods: Rockwell hardness (HRA) was tested according to GB / T7997–2014; flexural strength (MPa) was tested according to ISO3327 using the three-point bending method with a specimen size of 3×4×35mm; impact toughness (J / cm²) was tested according to GB / T229; corrosion resistance was tested by immersion in 5% sulfuric acid and 10% sodium hydroxide solution for 24 hours, and the corrosion weight loss (mg / cm²) was calculated. ); Neutral salt spray test (ISO 9227 test standard, salt solution: 5% NaCl, pH=7.0), record the time when corrosion spots appear.

[0147] The products of Examples 1-3 and Comparative Examples 1-8 were subjected to performance tests, and the test results are as follows;

[0148] Sample HRA Flexural strength / MPa Impact toughness / J·cm 5% sulfuric acid weight loss / mg.cm 10% alkali solution weight loss / mg.cm First rust time / h Example 1 88.2 2810 12.1 0.118 0.097 168h Example 2 91.8 3150 13.5 0.105 0.086 192h Example 3 90.1 3020 12.8 0.110 0.091 180h Comparative Example 1 87.5 2260 8.4 0.163 0.142 72h Comparative Example 2 88.1 2430 9.6 0.151 0.133 96h Comparative Example 3 88.5 2510 9.9 0.147 0.128 108h Comparative Example 4 88.3 2480 9.7 0.149 0.130 102h Comparative Example 5 88.0 2390 9.2 0.155 0.136 84h Comparative Example 6 88.2 2420 9.5 0.152 0.134 90h Comparative Example 7 87.8 2350 8.9 0.216 0.185 48h Comparative Example 8 88.4 2460 9.8 0.182 0.157 60h

[0149] Examples 1-3 exhibit the best overall performance: hardness HRA 88-92, flexural strength ≥ 2800 MPa, and impact toughness ≥ 12 J / cm². It exhibits low weight loss due to acid and alkali corrosion, and the product's initial rusting time in a neutral salt spray environment is ≥168h. It demonstrates excellent corrosion resistance, meeting the requirements of strong impact and corrosion conditions in mining and geological environments. The product's performance can be comprehensively and coordinated for improvement.

[0150] In Comparative Example 1, the toughness and strength of the product decreased significantly without carbon nanotube-modified carbon fiber agent, indicating that carbon nanotube-modified carbon fiber agent is the core of toughening and reinforcement. At the same time, the salt spray corrosion resistance of Comparative Example 1 decreased significantly, with the first corrosion occurring in only 72 hours, indicating that carbon fiber agent can optimize interface density and block corrosion channels.

[0151] Comparative Examples 2-6 lacked carbon fiber functional agents, tannic acid treatment, and the second additive. Ce powder and chromium powder were not added during the preparation of the first additive, and cobalt nitrate solution was not added during the preparation of the first additive. The performance of the products all showed a deterioration trend to varying degrees. Therefore, only the carbon nanotube-modified carbon fiber agent prepared by the specific method of this invention has the most significant performance effect. Other methods are not as good as the effect of this invention. At the same time, the preparation of the first additive is unique. The product prepared by the formula of this invention has the best performance effect.

[0152] Comparative Examples 7-8 showed significantly deteriorated corrosion resistance and insufficient grain boundary strengthening, demonstrating that boron-containing agents are crucial for corrosion resistance and grain boundary stability.

[0153] In Comparative Example 7, which did not contain boron agent, the salt spray resistance was the worst, with rust appearing in just 48 hours. This demonstrates that the boron agent is a key component for improving grain boundary corrosion resistance and inhibiting corrosion propagation. In Comparative Example 8, the boron agent was not added to the binder liquid, and uneven dispersion led to an increase in grain boundary defects and a significant decrease in corrosion resistance. This indicates that the binder liquid is crucial for the uniform distribution of the boron agent and for improving corrosion resistance stability. The carbon nanotube-regulated carbon fiber agent works synergistically with the boron agent to form a dense corrosion-resistant protective layer, extending the salt spray corrosion time by more than three times and significantly improving corrosion resistance stability.

[0154] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0155] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining, characterized in that, The raw materials include the following parts by weight: 65-75 parts of ultra-coarse tungsten carbide powder, 15-25 parts of iron-nickel-based binder, 5-9 parts of carbon nanotube-modified carbon fiber agent, 3-6 parts of boron agent, and 1-3 parts of molding agent.

2. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 1, characterized in that, The iron-nickel base has an iron to nickel weight ratio of (2-3):1; the ultra-coarse tungsten carbide powder has an average particle size of 5-8 μm; and the molding agent is one or more of paraffin wax, polyvinyl alcohol, and stearic acid.

3. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 1, characterized in that, The method for preparing the carbon nanotube-modified carbon fiber agent is as follows: S1, place carbon nanotubes in a first additive 3 to 5 times their total volume and sonicate them with an ultrasonic power of 350 to 400 W for 1 hour to obtain the first additive carbon nanotube liquid. The first carbon nanotube liquid and the second additive are mixed and ball-milled at a weight ratio of (11-15):5 to obtain the carbon nanotube liquid. S2, Preparation of carbon fiber functional agent: Tannic acid, ethanol, and silane coupling agent KH550 are stirred evenly in a weight ratio of (1-3):5:(1-2) to obtain tannic acid solution; tannic acid solution, nano titanium dioxide, and carbon fiber are mixed in a weight ratio of (5-8):(3-5):2, filtered and dried to obtain carbon fiber functional agent. S3, mix carbon nanotube liquid and carbon fiber functional agent at a weight ratio of (8-11):3, ball mill, filter, and dry to obtain carbon nanotube-modified carbon fiber agent.

4. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 3, characterized in that, The preparation method of the first admixture is as follows: Mix 1-2 parts of Ce powder, 2-3 parts of 3-5% cobalt nitrate solution, and 1-2 parts of chromium powder evenly, then add 1-2 parts of hexamethylenetetramine and 2-4 parts of lanthanum chloride solution and mix thoroughly to obtain the first additive.

5. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 4, characterized in that, The second additive is prepared by mixing molybdenum powder, nano-alumina, and tantalum carbide in a weight ratio of (1-2):(3-5):1 and sintering at 300-350°C for 1 hour to obtain the second additive.

6. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 5, characterized in that, The mass fraction of the lanthanum chloride solution is 2-4%; The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10–20 nm and a length of 10–30 μm. The carbon fiber is short-cut carbon fiber with a length of 50–200 μm and a diameter of 6–8 μm; the nano-titanium dioxide has a particle size of 20–50 nm and a crystal form of anatase. Ce powder has a particle size of 100–200 nm; the chromium powder has a particle size of 1–3 μm. The molybdenum powder has a particle size of 1–3 μm; the nano-alumina has a particle size of 20–40 nm; and the tantalum carbide has a particle size of 1–5 μm.

7. The high-strength, high-toughness, impact-resistant, ultra-coarse cemented carbide for mining as described in claim 1, characterized in that, The method for preparing the boron agent is as follows: S11, mix 2-4 parts of nano silica sol, 5-8 parts of sodium alginate solution with a mass fraction of 4-7% and 1-2 parts of silane coupling agent KH550 evenly to obtain a gel liquid; S12: Place boron oxide in a sodium citrate solution with a mass fraction of 8-12% and a total volume of 3-5 times the boron oxide and stir until homogeneous. Then add nano diamond powder with a total boron oxide content of 5-7% and a gel liquid with a total boron oxide content of 4-6%. Stir at 55-60℃ and 450-500 r / min for 1 hour. Filter and dry to obtain the boron-containing agent.

8. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining according to claim 7, characterized in that, The boron oxide particles have a diameter of 1–3 μm; the nanodiamond powder has a diameter of 30–80 nm.

9. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining as described in claim 1, characterized in that, The preparation steps of ultra-coarse cemented carbide are as follows: Step 1: Weigh out the ultra-coarse tungsten carbide powder, iron-nickel-based binder, carbon nanotube-modified carbon fiber agent, boron agent, and molding agent according to the formula, and place them in a ball mill for wet grinding. The ball-to-material ratio is (4-6):1, and the ball milling time is 24-36 hours to obtain a mixture. Step 2: Vacuum dry the mixture and pass it through a 100-200 mesh sieve to obtain spray-granulated powder; Step 3: The granulated powder is cold-pressed under a pressure of 150-200 MPa to obtain a pressed compact; Step 4: Vacuum sintering of the compact, heating to 400-500℃ to remove the forming agent, then heating at 10℃ / min to 1380-1450℃, holding for 1-2 hours, and cooling with the furnace to obtain a high-strength, tough, impact-resistant ultra-coarse cemented carbide for mining.

10. The high-strength, high-toughness, impact-resistant ultra-coarse cemented carbide for mining according to claim 9, characterized in that, Step 1: The wet grinding medium is anhydrous ethanol, with a solid-liquid ratio of 1:(2-3). Step 2: Vacuum drying temperature is 70-90℃, and drying time is 6-10h. Step 4: Vacuum degree is ≤5Pa.