Composite structure of carbide ceramic and steel and preparation method thereof

Abstract

The invention belongs to the field of wear-resistant materials, and particularly relates to a carbide ceramic and steel composite structure and a preparation method thereof. The method comprises the following steps: 1) preparing hard alloy powder slurry; (2) the carbide ceramics are subjected to cemented carbide treatment through cemented carbide powder slurry; (3) mixing the cemented carbide ceramic obtained in the step (2) with steel powder or cast iron powder according to a certain proportion, pressing into a green body, and sintering at a preset temperature; or molten steel is cast into the mold containing the cemented carbide ceramic obtained in the step 2), and the carbide / steel composite material with the internal structure having the carbide ceramic-cemented carbide layer-steel characteristics is prepared. According to the method, reaction of carbide ceramic and steel is blocked through the hard alloy layer, the problem that the carbide ceramic and the steel are difficult to compound is solved, and the prepared carbide / steel composite material has better hardness, impact toughness and wear resistance.

Description

Technical Field

[0001] The present invention belongs to the field of wear-resistant materials, and in particular relates to a composite structure of carbide ceramics and steel and a preparation method thereof. Background Art

[0002] Carbide ceramics have good wear resistance but poor toughness, being hard and brittle. For example, silicon carbide (SiC) ceramics not only possess excellent room-temperature mechanical properties, such as high flexural strength, excellent oxidation resistance, good corrosion resistance, high wear resistance, and a low coefficient of friction, but also boast the best high-temperature mechanical properties (strength, creep resistance, etc.) among known ceramic materials. Silicon carbide ceramics also have good oxidation resistance. However, as a whole, carbide ceramic material is too brittle, resulting in poor impact resistance and toughness.

[0003] Steel and cast iron have excellent toughness and impact resistance, but their wear resistance is inferior to that of carbide ceramics. The wear resistance coefficient of ordinary steel is generally between 0.3 and 1, while the wear resistance coefficient of rebar is 0.8 to 1.2 according to national standards. However, silicon carbide, a type of carbide ceramic, has a wear resistance over 200 times that of manganese steel and over 150 times that of high-chromium cast iron.

[0004] The carbide ceramic and steel are combined to form a carbide ceramic-steel composite material, which can give full play to the advantages of both. In order to obtain wear-resistant materials with better properties, the prior art proposes to prepare composite materials by sintering non-metallic and metal mixtures. For example, Patent 2007100299437 "Ceramic Particle Reinforced Iron-Based Composite Material and Preparation Method Thereof" discloses a method for preparing a ceramic particle reinforced iron-based composite material, which comprises (1) placing metal ceramic particles with a particle size of 1mm to 7mm in a casting mold, pouring molten steel or cast iron into the casting mold, and statically solidifying and cooling to prepare a ceramic particle reinforced iron-based composite material. However, the composite material obtained by this mixed sintering is not firmly bonded. In particular, carbide ceramics easily react with steel to form a brittle phase, which affects the bonding between the two and deteriorates the performance. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention proposes a composite structure of carbide ceramics and steel and a method for preparing the same. The present invention proposes introducing a cemented carbide layer between the carbide ceramics and the steel to block contact between the carbide ceramics and the steel. This prevents a reaction between the carbide ceramics and the steel, and because both the carbide ceramics and the cemented carbide layer are carbides, they easily combine to form a chemical bond. The carbides in the cemented carbide layer do not readily react with steel or cast iron, but can dissolve into them to form a solid solution. Furthermore, the Co or Ni in the cemented carbide layer can dissolve well with iron, allowing the two to bond well, thus resolving the previously difficult problem of composite carbide ceramics and steel.

[0006] During the implementation process, the cemented carbide slurry can be coated on the surface of the carbide ceramic by dipping or spraying, and the cemented carbide ceramic is obtained after degreasing and sintering; the cemented carbide ceramic is then compounded with steel by powder metallurgy or casting to finally obtain a wear-resistant material with an internal structure of carbide ceramic-cemented carbide layer-steel: carbide ceramic / steel or carbide ceramic / cast iron.

[0007] Specifically, on one hand, the present invention provides a method for preparing a composite structure of carbide ceramics and steel, the method comprising the following steps:

[0008] 1) preparing a cemented carbide powder slurry, wherein the cemented carbide powder slurry comprises at least: a hard phase powder, a binder phase powder, a solvent, an initiator, and an organic functional monomer matching the initiator;

[0009] 2) Carbide-forming the carbide ceramic using the cemented carbide powder slurry, which includes coating the carbide ceramic surface with the cemented carbide powder slurry, irradiating the coated carbide ceramic with UV light or heating the coated carbide ceramic to induce the initiator therein to initiate a polymerization reaction of the organic functional monomer to form a polymer, thereby coating the carbide ceramic surface with a layer of cemented carbide slurry solidified layer; and then sintering the carbide ceramic coated with the cemented carbide slurry to sinter and solidify the cemented carbide powder therein, thereby achieving cemented carbide-forming the silicon carbide ceramic surface.

[0010] 3) Mixing the cemented carbide ceramic obtained in step 2) with steel powder or cast iron powder in a certain proportion, pressing the mixture into a green body, and sintering the mixture at a predetermined temperature to produce a carbide / steel composite material having an internal structure characterized by carbide ceramic-cemented carbide layer-steel; or, casting molten steel into a mold containing the cemented carbide ceramic obtained in step 2) to produce a carbide / steel composite material having an internal structure characterized by carbide ceramic-cemented carbide layer-steel after solidification.

[0011] In a preferred implementation, the mass ratio of the hard phase powder and the bonding phase powder to the total slurry volume is 20% to 80%, and the remainder is a mixture of solvent, initiator and organic functional monomer. The mass ratio of the organic functional monomer to the solvent in the mixture is 1:99 to 30:70, and the amount of initiator added is 0.01% to 10% of the weight of the organic monomer.

[0012] In another preferred implementation, the mass ratio of the hard phase powder and the bonding phase powder to the total slurry volume is 30% to 50%; the weight ratio of the hard phase powder and the bonding phase powder is 1:10 to 100:0.1, preferably 1:10 to 10:1.

[0013] In another preferred implementation, the hard phase powder includes one or more of WC powder, TiC powder, titanium carbonitride powder, NbC powder or TaC powder, and the bonding phase powder includes one or more of Co powder, Ni powder, FeCo powder and FeNi alloy powder.

[0014] In another preferred implementation, the cemented carbide powder slurry further includes a dispersant and a thickener, wherein the dispersant is a mixture of one or more of ZN-1344, SP-710, and SP-6000, and the dispersant is 0.01% to 10% of the total mass of the hard phase powder and the bonding phase powder, and the thickener includes a mixture of one or more of carboxymethyl cellulose CMC, polyvinyl alcohol PVA, polyvinyl butyral PVB, and polyacrylamide PAM.

[0015] In another preferred implementation, in step 2), the process of coating the cemented carbide powder slurry on the surface of the cemented carbide powder slurry includes: coating the cemented carbide slurry on the surface of the carbide ceramic by dipping or spraying, and obtaining a cemented carbide ceramic after degreasing and sintering. During degreasing and sintering, in a hydrogen atmosphere, the temperature is gradually raised to a first temperature and then maintained, the atmosphere is switched to nitrogen, and the temperature is gradually raised to a second temperature and maintained.

[0016] In another preferred implementation, the organic functional monomer includes: 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, hydroxyethyl acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, acrylic acid, or a mixture of the above;

[0017] The initiator is a photoinitiator or a thermal initiator, and the thermal initiator includes one or more of benzoic acid peroxide, azobisisobutyronitrile, sodium azobiscyanovalerate, azo(2-(2-imidazole)propane) sodium hydrochloride, and azo(2-amidinopropane) hydrochloride; or

[0018] The photoinitiator includes one or more of 1-hydroxycyclohexylphenyl phosphine ketone, trimethylbenzoyl-diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0019] In another preferred implementation, the carbide ceramic includes one or a mixture of silicon carbide, boron carbide, chromium carbide or molybdenum carbide, etc. The size of the carbide ceramic is greater than or equal to 0.5 mm, and the shape is granular, lath-shaped, spherical or flake-shaped.

[0020] In another preferred implementation, when preparing the cemented carbide powder slurry in step (1), the hard phase powder, the binder phase powder, the solvent, and the organic functional monomer are first mixed and stirred, and 0.01h to 1h before the mixing and stirring is completed, the initiator is added and the mixing and stirring is continued.

[0021] On the other hand, the present invention provides a composite structure of carbide ceramics and steel, characterized in that the composite structure includes carbide ceramics, a cemented carbide layer and a steel material matrix. The carbide ceramics are combined with the steel material matrix through the cemented carbide layer to form a metallurgical alloy, so that it has the organizational structure characteristics of carbide ceramics-cemented carbide-steel. Preferably, the composite structure is made using the described method.

[0022] In step 2 of the present invention, the first temperature is lower than 1000 degrees Celsius, and the second temperature is higher than 1000 degrees Celsius.

[0023] If the pressing sintering method is used in step 3 of the present invention, the sintering temperature is higher than 1000 degrees Celsius. If the casting method is used, the casting temperature is 20-100 degrees Celsius higher than the melting point of steel, and the preferred casting temperature is 1400-1700 degrees Celsius.

[0024] The carbide ceramics used in the present invention are 0.5 mm or larger in size and may be in the form of granules, laths, spheres, or flakes, but are not limited thereto. The carbide ceramics used in the present invention are preferably, but are not limited to, a mixture of one or more of silicon carbide, boron carbide, chromium carbide, or molybdenum carbide.

[0025] The steel or cast iron material used in the present invention includes one or a mixture of high chromium steel, high manganese steel, low alloy steel or ductile iron, but is not limited thereto.

[0026] The cemented carbide layer used in the present invention includes WC-Co, WC-Ni, TiC-Fe, and Ti(C,N)-Ni, but is not limited thereto.

[0027] The cemented carbide process of the present invention includes: adding micron-sized cemented carbide powder to a solution containing an organic monomer and ball milling it; then, through thermal initiation or photoinitiation, causing the organic matter immersed or sprayed on the surface of the silicon carbide ceramic to react and wrap it; and then, after degreasing and sintering, forming a dense cemented carbide layer on the surface of the silicon carbide ceramic.

[0028] Beneficial effects

[0029] The present invention uses an organic polymerized method to coat a hard alloy layer between the carbide ceramic and the steel, thereby blocking direct contact between the carbide ceramic and the steel. On the one hand, this prevents the reaction between the carbide ceramic and the steel during the sintering process. On the other hand, since the carbide ceramic and the hard alloy layer are both carbides, the two can be directly and easily combined to form a chemical bond. Moreover, the carbides in the hard alloy layer do not easily react with steel or cast iron, but can be dissolved in the steel or cast iron to form a solid solution. At the same time, Co or Ni in the hard alloy layer can be well dissolved in iron, so the two can also be well combined, thereby solving the composite problem of the carbide ceramic and the steel.

[0030] Compared with composite structures prepared by the conventional direct powder metallurgy sintering method or smelting and pouring method, the composite structure prepared by the method of the present invention has a stronger bond and has higher hardness, impact toughness and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a schematic preparation flow chart of the composite structure preparation method according to the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of the composite structure prepared by the method of the present invention. The upper half of the figure is a schematic diagram of the structure of the composite of granular or small-block carbide ceramics and a steel matrix; the lower half is a schematic diagram of the structure of the composite of plate-like carbide ceramics and a steel matrix.

[0033] Figure 3 This is the crystal phase diagram of the reaction product in Example 2.

[0034] Figure 4 This is a physical picture of the reaction product in Example 4. DETAILED DESCRIPTION

[0035] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0036] The present invention provides a composite structure of carbide ceramic and steel or cast iron, and a method for preparing the same. Generally speaking, the method first coats carbide ceramic particles or blocks by dipping or spraying. After coating, a cemented carbide layer solidifies on the surface of the carbide ceramic through a curing reaction, forming a hard alloyed carbide ceramic. The carbide ceramic is then composited with steel or cast iron using powder metallurgy or casting methods, ultimately producing a wear-resistant material with an internal structure of carbide ceramic, cemented carbide layer, and steel or cast iron: carbide ceramic / steel or carbide ceramic / cast iron.

[0037] The following takes carbide ceramics as an example to explain in detail the method of compounding carbide ceramics with steel. Figure 1 As shown, the method includes the following steps:

[0038] 1. Preparation of cemented carbide powder slurry

[0039] A certain proportion of cemented carbide powder, solvent, organic functional monomer, initiator, dispersant and thickener are added into a ball mill and milled for a certain time to prepare cemented carbide powder slurry.

[0040] Cemented carbide powder comprises hard phase powder and binder phase powder. The hard phase powder includes, but is not limited to, one or more of WC powder, TiC powder, titanium carbonitride Ti(C,N) powder, NbC powder, or TaC powder. The binder phase powder includes, but is not limited to, one or more of Co powder, Ni powder, FeCo powder, and FeNi alloy powder. The weight proportion of the cemented carbide powder in the entire slurry is 40% to 99%, and the weight ratio of the hard phase powder to the binder phase powder is 1:10 to 100:0.1, preferably 1:10 to 10:1. Preferably, the combined mass of the hard phase powder and binder phase powder accounts for 40% to 70% of the total mass of the cemented carbide powder slurry.

[0041] The solvent is alcohol, acetone, toluene or a mixture thereof.

[0042] The organic functional monomers include, but are not limited to, one or more of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, hydroxyethyl acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and acrylic acid. The organic functional monomers referred to in the present invention are organic compounds that can form polymers when combined with an initiator under thermal or photoinitiation conditions.

[0043] The initiator is a thermal initiator or a photoinitiator. The thermal initiator is one or more of, but not limited to, benzoic acid peroxide, azobisisobutyronitrile, sodium azobiscyanovalerate, sodium azo(2-(2-imidazole)propane) hydrochloride, and azo(2-amidinopropane) hydrochloride. The photoinitiator is one or more of, but not limited to, 1-hydroxycyclohexylphenyl phosphine ketone, trimethylbenzoyl-diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. The amount of initiator added is 0.01% to 10% by weight of the organic monomer. The initiator is added last, 0.01 to 1 hour before discharging.

[0044] The dispersant is one or more of ZN-1344, SP-710, and SP-6000, but is not limited thereto. The amount of the dispersant added is 0.01% to 10% of the weight of the cemented carbide powder.

[0045] The thickener is one or more of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyacrylamide (PAM), etc., but is not limited thereto. The amount of the thickener added is 0.01% to 20% of the weight of the solvent.

[0046] The ball mill can be, but is not limited to, a drum ball mill or a planetary ball mill. The grinding balls are carbide balls. The ball-to-material ratio is 1:10 to 10:1. The ball milling time is 0.1 to 50 hours.

[0047] The carbide ceramic is one or a mixture of silicon carbide, boron carbide, chromium carbide or molybdenum carbide, but is not limited thereto.

[0048] The carbide ceramics are of a size larger than millimeter (above 0.5 mm) and are in the form of particles, laths, spheres or flakes, but are not limited thereto.

[0049] The cemented carbide layer is made of, but not limited to, WC-Co, WC-Ni, TiC-Fe, or Ti(C,N)-Ni. The thickness of the cemented carbide layer is 0.01 mm to 100 mm.

[0050] 2. Preparation of Cemented Carbide Ceramics

[0051] The preparation of cemented carbide ceramics includes: coating the surface of the carbide ceramic with a cemented carbide slurry by dipping or spraying, then placing the carbide ceramic coated with the cemented carbide slurry into a sintering furnace, and performing metal degreasing and sintering through thermal or photoinitiation to obtain a carbide ceramic coated with a cemented carbide layer: carbide ceramic @ cemented carbide. This step can be completed by the following methods:

[0052] Method 1

[0053] (1) Immersion method

[0054] (1.1) Thermal Initiation: If the initiator added in step 1 is a thermal initiator, immerse the carbide ceramic in the cemented carbide slurry prepared in step 1 for 0.1 to 60 minutes, then remove it and bake it in an oven at 50 to 100°C for 0.01 to 12 hours. The organic matter in the slurry undergoes a polymerization reaction under the action of the initiator, enveloping the carbide ceramic. The coating thickness is controlled within the range of 0.01 to 100 mm. If the coating thickness does not meet the requirements, repeat the immersion process or perform the following spraying method.

[0055] (1.2) Photoinitiator: If the initiator added in step 1 is a photoinitiator, immerse the carbide ceramic in the cemented carbide slurry prepared in step 1 for 0.1 to 60 minutes. Then remove it and place it in a UV oven for 0.01 to 12 hours. The organic matter in the slurry undergoes polymerization under the action of the initiator, enveloping the carbide ceramic. The coating thickness is controlled within the range of 0.01 to 100 mm. If the coating thickness does not meet the requirements, repeat the immersion process or use the spray coating method described below.

[0056] Preferably, the cemented carbide slurry is subjected to vacuum degassing treatment before dipping.

[0057] Preferably, the immersion method is suitable for carbide ceramics with smaller sizes, such as granules and spheres.

[0058] Method 2

[0059] (2) Spraying method

[0060] (2.1) If the initiator added in step 1 is a thermal initiator, use a spray bottle to evenly spray the cemented carbide slurry onto the surface of the carbide ceramic. Then, bake it in an oven at 50-100°C for 0.01-12 hours. The organic matter in the slurry will react and coat the carbide ceramic. The coating thickness should be within the range of 0.01mm-100mm. If the coating thickness does not meet the requirements, repeat the dipping process or use the following spraying method.

[0061] (2.2) If the initiator added in step 1 is a photoinitiator, use a spray bottle to evenly spray the cemented carbide slurry onto the surface of the carbide ceramic. Then place it in a UV oven and irradiate for 0.01 to 12 hours. The organic matter in the slurry will react and coat the carbide ceramic. The coating thickness should be within the range of 0.01 to 100 mm. If the coating thickness does not meet the requirements, repeat the dipping process or use the following spraying method.

[0062] Preferably, the cemented carbide slurry is subjected to vacuum degassing treatment before spraying.

[0063] Preferably, the spraying method is suitable for carbide ceramics with larger sizes, such as laths and sheets.

[0064] 3. Carbide ceramics @ composites of cemented carbide and steel or cast iron

[0065] Carbide ceramics@hard alloy are compounded with steel or cast iron to produce a wear-resistant material having an internal structure of carbide ceramics-hard alloy layer-steel or cast iron: carbide ceramics / steel or carbide ceramics / cast iron.

[0066] The steel or cast iron is one or a mixture of high chromium steel, high manganese steel, low alloy steel or ductile iron, but is not limited thereto.

[0067] This step can be achieved by the following method:

[0068] (1) The hard alloyed carbide ceramic prepared in step 2 is mixed with steel powder or cast iron powder in a certain weight ratio, placed in a mold and pressed into a green body, and then placed in a sintering furnace and sintered at a certain temperature to form a block material.

[0069] The weight ratio of the carbide ceramic@hard alloy to the steel powder or cast iron powder is 0.1:100 to 10:0.1.

[0070] The sintering temperature is 0.65 to 0.95 of the melting point of steel powder or cast iron powder.

[0071] Preferably, the immersion method is suitable for carbide ceramics and cemented carbides with smaller sizes, such as granules and spheres.

[0072] (2) Casting method

[0073] The carbide ceramic @ hard alloy prepared in step 2 is placed at the bottom of the mold, and steel or cast iron is heated to a certain temperature, melted, and then poured on its surface. At the same time, a vibration pump is used to vibrate the mold to allow the liquid steel or cast iron to completely infiltrate the carbide ceramic @ hard alloy, and finally solidify into shape.

[0074] The melting temperature is higher than the melting point of steel powder or cast iron powder by more than 100°C.

[0075] Preferably, the casting method is suitable for carbide ceramics@cemented carbide with larger sizes, such as laths and sheets.

[0076] like Figure 2 The diagram shows the structure of a composite material formed by pressing, sintering, or casting. It should be noted that if sheet-shaped silicon carbide ceramics are used, their size should not be too large. If large sheets are used, they should be used in applications where impact resistance is not required.

[0077] Example 1:

[0078] D 50 10mm millimeter-sized silicon carbide ceramic particles are composited with high-chromium cast iron Cr28, and the cemented carbide layer is WC-6Co (YG6)

[0079] In this example, the preparation process of the composite structure is as follows:

[0080] Weigh 0.94 kg of WC powder (D 50 10μm), 0.06Kg Co powder (D 502μm), 50g of toluene, 10g of hydroxyethyl methacrylate, 0.5g of methylenebisacrylamide and 0.01g of dispersant SP-6000 were added into a drum ball mill equipped with 1kg of cemented carbide balls and ball-milled for 2h. Then, 5g of carboxymethyl cellulose was added in three portions and ball-milled for 1h. Then, 0.1g of azobisisobutyronitrile was added and ball-milled for 1h to obtain a thermally initiable cemented carbide slurry.

[0081] Weigh 3 kg of millimeter-sized SiC ceramic particles (D 50 10mm) is soaked in the above-mentioned cemented carbide slurry for 2 minutes, then taken out and placed in an oven at 80°C for 1 hour (to induce polymerization of the organic matter therein) until the surface slurry hardens. Repeat this process twice. The particles are then placed in a cemented carbide sintering furnace, heated to 600°C at 1°C / min in a hydrogen atmosphere, and kept warm for 1 hour. The atmosphere is converted to nitrogen, and then heated to 1430°C at 5°C / min for 2 hours. Degreasing and sintering are performed to obtain particles with a cemented carbide layer coated on the surface of silicon carbide, which are referred to here as SiC@YG6.

[0082] 2.5 kg of SiC@YG6 particles were weighed and placed in a steel mold, which was then placed on a vibration table. High-chromium cast iron Cr28 was melted at 1500°C and the vibration table was turned on until the liquid Cr28 completely entered the gaps between the particles and solidified, thereby producing a SiC-Cr28 composite material.

[0083] The hardness, impact toughness, and wear resistance of the SiC-Cr28 composite material prepared in Example 1 were tested. The hardness test standard was GB / T 230.1-2018, the impact toughness test standard was GB / T229-2020, and the wear resistance test standard was GB / T 34501-2017. The hardness of the wear-resistant material was 71.1HRC and the impact toughness was 3.2J / cm 2 The abrasive wear rate was 0.8 g / 10 min. The test results show that the comprehensive performance parameters of the composite material prepared in this example are significantly better than those of carbide ceramics, cemented carbide or steel materials used alone.

[0084] The SiC-Cr28 composite material prepared in Example 1 was analyzed by crystal phase analysis, and it was found that a hard alloy transition layer of about 1 mm was present between SiC and Cr28.

[0085] Example 2, D 50 20mm millimeter-sized silicon carbide ceramic particles are composited with low carbon steel Q235, and the carbide layer is WC-15Ni

[0086] In this example, the preparation process of the composite structure is as follows:

[0087] Weigh 0.85Kg WC powder (D 5010μm), 0.15Kg Ni powder (D 50 2μm), 40g of hydroxyethyl methacrylate, 10g of pentaerythritol triacrylate and 0.1g of dispersant ZN-1344 were added into a drum ball mill equipped with 1.2Kg of cemented carbide balls and ball-milled for 1.5h. Then, 6g of polyvinyl alcohol was added in three portions and ball-milled for another 1h. Then, 0.1g of benzoic acid peroxide was added and ball-milled for another 0.5h to obtain a heat-initiable cemented carbide slurry.

[0088] Weigh 3 kg of millimeter-sized SiC ceramic particles (D 50 20mm) was soaked in the above-mentioned cemented carbide slurry for 2 minutes, then taken out and placed in an oven at 70°C for 2 hours until the surface slurry hardened. This process was repeated three times. The particles were then placed in a cemented carbide sintering furnace, heated to 620°C at 0.5°C / min in a hydrogen atmosphere, and kept warm for 1 hour. The atmosphere was switched to nitrogen, and then heated to 1470°C at 5°C / min and kept warm for 2 hours. Degreasing and sintering were performed to obtain particles with a cemented carbide layer coated on the surface of silicon carbide, which are referred to here as SiC@WC-15Ni.

[0089] 3 kg of SiC@WC-15Ni particles were weighed and placed in a steel mold, which was then placed on a vibration table. Low carbon steel Q235 was melted at 1600 °C and the vibration table was turned on until the liquid low carbon steel Q235 completely entered the gaps between the particles and solidified, thereby obtaining a SiC-low carbon steel Q235 composite material.

[0090] The hardness, impact toughness, and wear resistance of the SiC-Q235 composite material prepared in Example 2 were tested. The hardness test standard was GB / T 230.1-2018, the impact toughness test standard was GB / T229-2020, and the wear resistance test standard was GB / T 34501-2017. The hardness of the wear-resistant material was 72.3HRC and the impact toughness was 4.8J / cm 2 , abrasive wear 0.7g / 10min.

[0091] The crystal phase analysis of the SiC-Q235 composite material prepared in Example 2 revealed that there was a 2mm hard alloy transition layer between SiC and Q235. Figure 3 As shown in the figure, the left side is the base material and the right side is the silicon carbide material. There is a certain transition area in the middle part, which is colored blue.

[0092] Example 3, D 50 15mm millimeter-sized silicon carbide ceramic particles are composited with ductile iron HT, and the carbide layer is TiC-10Co

[0093] In this example, the preparation process of the composite structure is as follows:

[0094] Weigh 0.90Kg TiC(D 50 10μm), 0.1Kg Co powder (D 50 2μm), 20g of alcohol, 30g of hydroxyethyl acrylate, 10g of trimethylolpropane triacrylate and 0.05g of dispersant SP-710 were added into a drum ball mill equipped with 1kg of cemented carbide balls and ball-milled for 2h. Then, 4g of polyacrylamide was added in three portions and ball-milled for 1h. Then, 0.1g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide was added and ball-milled for 1h to obtain a photoinitiable cemented carbide slurry.

[0095] Weigh 4 kg of millimeter-sized silicon carbide ceramic particles (D 50 The particles were then placed in a cemented carbide slurry and heated at a rate of 1°C / min to 600°C in a hydrogen atmosphere for 1 hour. The atmosphere was then switched to nitrogen and the temperature was then raised to 1480°C at a rate of 5°C / min for 2 hours. The particles were then degreased and sintered to obtain particles with a cemented carbide layer coated on the surface of the silicon carbide, referred to herein as silicon carbide SiC@TiC-10Co.

[0096] 2.5 kg of silicon carbide @ TiC-10Co particles were weighed and mixed evenly with 5 kg of ball-milled cast iron powder HT powder. The mixture was then placed into a steel mold and pressed into shape at 20 MPa. The mixture was then sintered at 1100 ° C for 2 hours under vacuum to obtain a silicon carbide-ball-milled cast iron HT composite material.

[0097] The hardness, impact toughness, and wear resistance of the SiC-HT composite material prepared in Example 3 were tested according to the GB / T 230.1-2018 standard for hardness, the GB / T 229-2020 standard for impact toughness, and the GB / T 34501-2017 standard for wear resistance. The results showed that the wear-resistant material had a hardness of 68.3 HRC and an impact toughness of 4.1 J / cm 2 , abrasive wear 0.85g / 10min.

[0098] Crystal phase analysis of the SiC-HT composite material prepared in Example 3 revealed the presence of a cemented carbide transition layer of approximately 1.3 mm between SiC and HT.

[0099] Example 4, D 50 8mm millimeter-sized boron carbide ceramic particles are compounded with manganese steel NM600, and the carbide layer is WC-20Co (Co content accounts for 20% of the total mass)

[0100] In this example, the preparation process of the composite structure is as follows:

[0101] Weigh 0.80Kg WC powder (D 50 10μm), 0.20Kg Co powder (D 50 10μm), 50g of toluene, 10g of hydroxyethyl methacrylate, 0.5g of methylenebisacrylamide and 0.02g of dispersant SP-6000 were added into a drum ball mill equipped with 1Kg of cemented carbide balls and ball-milled for 1h. Then, 6g of methyl cellulose was added in 4 times and ball-milled for another 0.5h. Then, 0.2g of trimethylbenzoyl-diphenylphosphine oxide was added and ball-milled for another 1h to obtain a photoinitiable cemented carbide slurry.

[0102] Weigh 3 kg of millimeter-sized boron carbide ceramic particles (D 50 8mm) was soaked in the above-mentioned cemented carbide slurry for 2 minutes, then taken out and placed in a UV oven for 1.5 hours of irradiation until the surface slurry hardened. This process was repeated three times. The particles were then placed in a cemented carbide sintering furnace, heated to 600°C at 0.5°C / min in a hydrogen atmosphere and kept warm for 2 hours. The atmosphere was switched to nitrogen, and the temperature was then raised to 1450°C at 6°C / min and kept warm for 2 hours. Degreasing and sintering were performed to obtain particles with a boron carbide surface coated with a cemented carbide layer, referred to herein as boron carbide@WC-20Co.

[0103] 2.5 kg of boron carbide@WC-20Co particles were weighed and placed in a steel mold and placed on a vibration table. Manganese steel NM600 melted at 1650°C was injected into the steel mold and the vibration table was turned on until the liquid manganese steel NM600 completely entered the gaps between the particles and solidified, thereby obtaining a boron carbide-manganese steel NM600 composite material.

[0104] The hardness, impact toughness, and wear resistance of the boron carbide-NM600 composite material prepared in Example 4 were tested. The hardness test standard was GB / T 230.1-2018, the impact toughness test standard was GB / T 229-2020, and the wear resistance test standard was GB / T 34501-2017. The hardness of the wear-resistant material was 68.6HRC and the impact toughness was 2.8J / cm 2 , abrasive wear 1.9g / 10min.

[0105] The boron carbide-NM600 composite material prepared in Example 4 was analyzed by crystal phase analysis, and it was found that a cemented carbide transition layer of about 1.6 mm was present between the boron carbide and HT.

[0106] From the test results, the comprehensive performance parameters of the composite materials prepared in Examples 2-4 of the present invention are also significantly better than those of carbide ceramics, cemented carbide or steel materials used alone.

[0107] Example 5

[0108] In this example, silicon carbide particles are directly cast with steel to form a composite. First, the silicon carbide particles are placed in a mold, and high-chromium cast iron Cr28 melted at 1500°C is cast into it. When the molten steel and silicon carbide come into direct contact, they react directly to form complex iron silicide and graphite, significantly deteriorating the interface bonding performance. The results of the obtained product are as follows: Figure 4 As shown, silicon carbide reacts with steel, leaving behind numerous defects. Figure 4 The image shows holes left by the direct reaction of silicon carbide and steel at high temperatures, leaving almost no silicon carbide.

[0109] Example 6

[0110] In this example, silicon carbide particles and steel powder are compounded by powder metallurgy sintering. The silicon carbide particles and Cr28 powder are evenly mixed and pressed into a billet, and the billet is gradually heated. When the temperature rises to above 800°C, the two begin to react to generate complex iron silicide and graphite, and the interface bonding performance is significantly deteriorated. The final material has many defects and poor wear resistance. The sintering temperature of normal powder metallurgy is above 1200°C. Considering the reaction, it is only heated to 800°C without further heating.

[0111] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite structure of carbide ceramics and steel, characterized in that: The method comprises the following steps: 1) preparing a cemented carbide powder slurry, wherein the cemented carbide powder slurry comprises at least: a hard phase powder, a binder phase powder, a solvent, an initiator, and an organic functional monomer matching the initiator; 2) Carbide-forming the carbide ceramic using the cemented carbide powder slurry, which includes coating the carbide ceramic surface with the cemented carbide powder slurry, irradiating the coated carbide ceramic with UV light or heating the coated carbide ceramic to induce the initiator therein to initiate a polymerization reaction of the organic functional monomer to form a polymer, thereby coating the carbide ceramic surface with a layer of cemented carbide slurry solidified layer; and then sintering the carbide ceramic coated with the cemented carbide slurry to sinter and solidify the cemented carbide powder therein, thereby achieving cemented carbide-forming the silicon carbide ceramic surface. 3) Mixing the cemented carbide ceramic obtained in step 2) with steel powder or cast iron powder in a certain proportion, pressing the mixture into a green body, and sintering the mixture at a predetermined temperature to produce a carbide / steel composite material having an internal structure characterized by carbide ceramic-cemented carbide layer-steel; or, casting molten steel into a mold containing the cemented carbide ceramic obtained in step 2) to produce a carbide / steel composite material having an internal structure characterized by carbide ceramic-cemented carbide layer-steel after solidification.

2. The method for preparing a composite structure according to claim 1, wherein: The mass ratio of the hard phase powder and the bonding phase powder to the total volume of the slurry is 20% to 80%, and the rest is a mixture of solvent, initiator and organic functional monomer. The mass ratio of the organic functional monomer to the solvent in the mixture is 1:99 to 30:70, and the amount of the initiator added is 0.01% to 10% of the weight of the organic monomer.

3. The method for preparing a composite structure according to claim 2, wherein: Hard phase The mass ratio of the powder and the bonding phase powder to the total slurry volume is 30% to 50%; the weight ratio of the hard phase powder to the bonding phase powder is 1:10 to 100:0.1, preferably 1:10 to 10:

1.

4. The method for preparing a composite structure according to claim 3, wherein: The hard phase powder includes one or more of WC powder, TiC powder, titanium carbonitride powder, NbC powder or TaC powder, and the bonding phase powder includes one or more of Co powder, Ni powder, FeCo powder and FeNi alloy powder.

5. The method for preparing a composite structure according to claim 1, wherein: The cemented carbide powder slurry also includes a dispersant and a thickener. The dispersant is one or a mixture of ZN-1344, SP-710, and SP-6000. The dispersant is 0.01% to 10% of the total mass of the hard phase powder and the bonding phase powder. The thickener includes one or a mixture of carboxymethyl cellulose CMC, polyvinyl alcohol PVA, polyvinyl butyral PVB, and polyacrylamide PAM.

6. The method for preparing a composite structure according to claim 1, wherein: In the step 2), the process of coating the cemented carbide powder slurry on the surface of the cemented carbide powder slurry includes: coating the cemented carbide slurry on the surface of the carbide ceramic by dipping or spraying, and obtaining a cemented carbide ceramic after degreasing and sintering. During degreasing and sintering, the temperature is gradually raised to a first temperature under a hydrogen atmosphere and then kept warm. The atmosphere is switched to nitrogen, and then the temperature is gradually raised to a second temperature and kept warm. Preferably, the first temperature is lower than 1000 degrees Celsius and the second temperature is higher than 1000 degrees Celsius. If the pressing and sintering method is adopted in the step 3, the sintering temperature is higher than 1000 degrees Celsius; if the casting method is adopted, the casting temperature is 20-100°C higher than the melting point of steel, and the preferred casting temperature is 1400-1700°C.

7. The method for preparing a composite structure according to claim 1, wherein: The organic functional monomer includes: 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, hydroxyethyl acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, acrylic acid, or a mixture thereof; The initiator is a photoinitiator or a thermal initiator, and the thermal initiator includes one or more of benzoic acid peroxide, azobisisobutyronitrile, sodium azobiscyanovalerate, azo(2-(2-imidazole)propane) sodium hydrochloride, and azo(2-amidinopropane) hydrochloride; The photoinitiator includes one or more of 1-hydroxycyclohexylphenyl phosphine ketone, trimethylbenzoyl-diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

8. The method for preparing a composite structure according to claim 1, wherein: The carbide ceramic includes one or a mixture of silicon carbide, boron carbide, chromium carbide or molybdenum carbide. The size of the carbide ceramic is greater than or equal to 0.5 mm and the shape is granular, lath, spherical or sheet.

9. The method for preparing a composite structure according to claim 1, wherein: When preparing the cemented carbide powder slurry in step (1), the hard phase powder, the binder phase powder, the solvent, and the organic functional monomer are first mixed and stirred. 0.01h to 1h before the mixing and stirring is completed, the initiator is added and the mixing and stirring is continued.

10. A composite structure of carbide ceramics and steel, characterized in that: The composite structure includes carbide ceramics, a cemented carbide layer, and a steel material matrix. The carbide ceramics are combined with the steel material matrix through the cemented carbide layer to form a metallurgical alloy, so that it has the organizational structure characteristics of carbide ceramics-cemented carbide-steel. The composite structure is manufactured using the method described in any one of claims 1 to 9.

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