606results about How to "Enhanced interface binding" patented technology

The invention provides a glass fiber reinforced nylon composite material and a preparation method thereof, and belongs to the technical field of high polymer materials, the glass fiber reinforced nylon composite material comprises the following components by weight: 75-82 parts of nylon 6, 14-16 parts of modified glass fiber, 2-3 parts of polyethylene glycol, 0.4-0.7 part of an antioxidant, 0.6-1 part of a lubricant and 0.6-1 part of an antistatic agent; the modified glass fibers are prepared by treating glass fibers with a silane coupling agent and then treating the glass fibers with a dopamine-boron nitride surface modifier. The excellent tensile strength of the prepared composite material is guaranteed, and meanwhile, the reduction of the elongation at break is effectively avoided, so that the fatigue resistance of the composite material is guaranteed, and the service life is further prolonged.

The invention relates to a copper-steel composite plate and a preparation method thereof, the copper-steel composite plate comprises an outer layer carbon steel plate and a core layer oxygen-free pure copper plate, and at least one surface of the oxygen-free pure copper plate integrally and continuously covers the carbon steel plate; the carbon steel plate comprises the following chemical components: 0.05%-0.20% of C, 0.1%-0.55% of Si, 0.5%-2.0% of Mn, less than or equal to 1.0% of Cr, less than or equal to 1.5% of Ni, less than or equal to 1.0% of Cu and the balance of Fe. The thickness of the copper-steel composite plate is 30-120 mm, and the ratio of the thickness of the oxygen-free pure copper plate to the thickness of the copper-steel composite plate is 0.4-0.8. According to the copper-steel composite plate, the yield strength is larger than or equal to 209 MPa, the tensile strength is larger than or equal to 359 MPa, the shear strength is larger than or equal to 213 MPa, and the copper-steel composite plate has good structural strength and interface bonding strength.

The invention belongs to the technical field of titanium alloy materials and additive manufacturing, and relates to a high-performance titanium-based composite material based on additive manufacturing and a preparation method of the high-performance titanium-based composite material. The preparation method comprises the following steps that titanium alloy powder subjected to vacuum drying treatment and titanium-coated reinforced phase nanoparticles are added into a ball mill to be subjected to ball milling treatment in the inert gas atmosphere, and evenly-mixed composite powder is obtained; and after the composite powder in the first step is subjected to vacuum drying, the composite powder is evenly laid on a forming base plate through additive manufacturing equipment, the composite powder is molten layer by layer through a heat source, and the high-performance titanium-based composite material is obtained after solidification. According to the titanium-based composite material and the preparation method thereof, TiB generated by the in-situ reaction of the B element in the titanium-coated reinforced phase nanoparticles and the Ti element in selective laser melting forming is adopted, the TiB is uniformly dispersed and distributed in a titanium alloy matrix, the prepared titanium-based composite material has good density, the strength, hardness and other properties of the material are obviously improved, and the comprehensive mechanical property is excellent.

The invention discloses a composite rubber material with wear resistance and high tear strength and a preparation method of the composite rubber material, and belongs to the technical field of rubber material processing. The technical problem that the enhancement effect of the filler on the wear resistance, tear resistance and mechanical strength of a rubber matrix needs to be further improved exists in the prior art. The composite material comprises the following components in parts by weight: 100-110 parts of internal mixed rubber, 1-2 parts of a vulcanization accelerator and 2-3 parts of a vulcanizing agent, modified polybutadiene is reinforced by aramid pulp, modified carbon black and modified graphene to prepare composite polybutadiene, and then styrene butadiene rubber is reinforced and modified by the prepared composite polybutadiene and silicone rubber to prepare the composite material. By improving the degree of crosslinking between material molecules and optimizing material composition, the wear resistance and tear resistance of the composite rubber material are effectively improved, and the mechanical property of the composite rubber material is also improved.

The invention discloses a high-strength silk fibroin / hydroxyapatite bone repair material and a preparation method thereof, and belongs to the field of biomedical materials. Methacrylic acid esterified silk fibroin and methacrylic acid esterified nano-hydroxyapatite are used as organic matter and inorganic filler, and the interface bonding capacity and dispersion stability between the organic component silk fibroin and the inorganic component hydroxyapatite are improved through photo-crosslinking; and performing high-temperature hot-pressing molding to obtain the silk fibroin / hydroxyapatite bone repair material. The bone repair material has relatively strong mechanical properties, osteogenesis induction capability, good biocompatibility and degradability, and has a wide application prospect in the field of bone defect repair.

The invention discloses a high-performance special ceramic material and a preparation process thereof, and the preparation process comprises the following steps: proportioning tungsten carbide, ternary boride, titanium nitride, molybdenum, nickel, silicon, cobalt and other raw materials with nano silicon carbide whiskers according to a ratio, carrying out ball milling treatment, adding a forming agent, and continuing ball milling and granulation; and then, carrying out compression molding on the ceramic powder, carrying out liquid phase sintering in a CO atmosphere, and cooling to room temperature to obtain the high-performance special ceramic material. The Mo3NiB3 ternary boride is introduced, so that the hardness and impact resistance of the ceramic material can be improved, the interface bonding force between a ceramic matrix and a reinforcing phase is enhanced, and the bending strength is improved; the nano silicon carbide whiskers are subjected to nickel plating treatment, so that the interface bonding force can be improved, microcracks are reduced, and the strength and toughness of the ceramic material are enhanced; by optimizing the sintering process and adopting a staged heating mode, grain growth can be controlled, and the density and mechanical properties of the ceramic material are effectively improved.

The invention belongs to the technical field of fiber metal laminates, and particularly discloses an anti-shearing fiber metal laminate and a preparation method thereof. A stainless steel ultra-thin belt, carbon fiber woven cloth and one-way carbon fiber prepreg are laid according to a laying scheme of [W / [G / 0 / G / 90] 2 / Gc] s, modified epoxy resin is coated between every two layers in the laying process, and the anti-shearing fiber metal laminate is obtained after curing; wherein W represents the carbon fiber woven cloth, G represents the stainless steel ultra-thin strip, 0 represents the unidirectional carbon fiber prepreg laid at 0 degree, 90 represents the unidirectional carbon fiber prepreg laid at 90 degrees, Gc represents the central layer, s represents the symmetrical laying layers along the central layer, and 2 represents the repetition frequency of [G / 0 / G / 90]. According to the prepared anti-shearing fiber metal laminate, the anti-shearing performance of the fiber metal laminate is greatly improved, and the possibility of damage such as layering damage, matrix fracture, fiber fracture and metal plastic deformation is reduced.

The invention relates to the field of cables, and discloses a high-strength corrosion-resistant ship cable and a preparation method thereof.The high-strength corrosion-resistant ship cable comprises a guide core, an insulating layer wrapping the outer portion of the guide core, a shielding layer wrapping the outer portion of the insulating layer and a sheath layer wrapping the outer portion of the shielding layer; the sheath layer comprises the following components in parts by weight: 40-55 parts of polyvinyl chloride, 20-30 parts of nitrile rubber, 5-15 parts of modified basalt fiber, 3-8 parts of a flame retardant, 1-2 parts of a lubricant and 0.1-1 part of a light stabilizer; the modified basalt fiber is a basalt fiber grafted macromolecular antioxidant modified basalt fiber, and the flame retardant is prepared from the following raw materials: phosphonitrilic chloride trimer, DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and a hydroxyl-terminated phosphorus-containing intermediate. The cable is endowed with excellent mechanical property, salt spray corrosion resistance, thermo-oxidative aging resistance and flame retardant property.

The invention relates to a self-repairing waterborne polyurethane composite elastomer based on dynamic interface reinforcing and toughening as well as a preparation method and application thereof, and belongs to the technical field of self-repairing high polymer materials. The method comprises the following steps: preparing a waterborne polyurethane emulsion; the preparation method comprises the following steps: uniformly dispersing polyvinylpyrrolidone in an ethanol solution, adding polyfunctional mercaptan and polyfunctional isocyanate, and adding an amino-containing imidazole monomer to obtain microsphere powder; and uniformly dispersing the microsphere powder in a waterborne polyurethane emulsion, adding a metal salt solution, and then volatilizing water to form a film material, thereby obtaining the self-repairing waterborne polyurethane composite elastomer based on dynamic interface reinforcement and toughening. The self-repairing waterborne polyurethane elastomer with excellent comprehensive performance is obtained by designing the structure of waterborne polyurethane, modifying the surface of the microsphere and introducing a dynamic interface for compounding, and the strength, the toughness and the self-repairing capability of the elastomer are simultaneously improved.

The invention relates to the technical field of aluminum alloy material pressure processing, in particular to an aluminum alloy material for preparing a steel-aluminum composite strip and a preparation method thereof.The aluminum alloy material comprises a steel layer and an aluminum alloy layer, and the aluminum alloy layer comprises, by mass, 100 parts of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn) and the balance aluminum and inevitable impurity elements. According to the method, through the laser interface activation and ultrasonic-assisted rolling technology, the interface bonding degree and the microstructure of the steel-aluminum composite material are remarkably improved, and the stability of the steel-aluminum composite material at the high temperature is optimized. And microalloying elements such as scandium (Sc) are introduced, so that the mechanical property and the corrosion resistance of the material are enhanced. The service life is prolonged through a special high-temperature-resistant coating and an accurate heat treatment process, and the surface hardness and corrosion resistance are improved. The advanced processes ensure high performance and high quality of the composite material, and meet the requirements of high temperature and special environments.

The invention relates to the technical field of all-vanadium redox flow batteries, and discloses a carbon grid derived multi-layer composite bipolar plate for a vanadium battery and a preparation method of the carbon grid derived multi-layer composite bipolar plate for the vanadium battery. The preparation method comprises the following steps: brushing a mixed slurry 1 prepared from a conductive filler, a binder and the like onto the surface to obtain preliminarily modified carbon fibers, then brushing a mixed slurry 2 prepared from oxide nanoparticles, conductive macromolecules and the like onto two surfaces of the preliminarily modified carbon fibers, drying, and repeating the two brushing and drying steps to obtain multi-layer conductive support layer modified carbon fibers; graphite paper is attached to the obtained carbon fibers, and then hot pressing treatment is performed to obtain the carbon conductive grid derived multi-layer composite bipolar plate. According to the prepared multi-layer composite bipolar plate, the etched carbon fiber is used as a substrate, beneficial mechanical strength and conductive grids are provided through stacking of the multiple layers of conductive coatings, the stability and conductivity of the bipolar plate are effectively improved, and therefore the efficiency of a vanadium battery is improved.

The invention provides a carbon nanotube modified polypropylene composite material and a preparation method thereof, and belongs to the technical field of antibacterial materials. According to the method, plant fibers are used as precursors, carbon nanotubes are prepared through high-temperature calcination, and the carbon nanotubes are subjected to surface activation treatment by using aids such as L-cysteine hydrochloride, sodium ascorbate and ethylenediamine, so that the dispersity and interface bonding force of the carbon nanotubes in a polypropylene matrix are remarkably improved. And then, mixing the modified carbon nano tube with polypropylene, polyhydric alcohol and a catalyst, reacting, and granulating through a double-screw extruder to prepare the composite material with excellent performance. The composite material disclosed by the invention has excellent mechanical properties, thermal stability, antibacterial property and conductivity, and is suitable for the fields of automobile parts, electronic device shells, building materials, medical apparatuses and instruments and the like. The method is simple in process, environment-friendly and efficient, renewable resources are fully utilized, and the method has a wide industrial application prospect.

The invention relates to the field of textile processing, and discloses a polyester knitted fabric flame-retardant finishing method, which is characterized in that modified waterborne polyurethane emulsion is finished on a washed and dried polyester knitted fabric by using a dipping and drying method; the modified waterborne polyurethane emulsion is prepared from isophorone diisocyanate, an amine chain extender, a flame-retardant cross-linking agent, modified nano titanium dioxide and the like, and the amine chain extender is prepared from 2-(2, 4-dihydroxyphenyl)-2H-benzotriazole and 2-chloro-4, 6-diamino-1, 3, 5-triazine through a reaction; the flame-retardant cross-linking agent is prepared from 1, 3, 5-tri (2-hydroxyethyl) cyanuric acid and dimethyl methylphosphonate through a reaction; the modified nano titanium dioxide is prepared from modified silane coupling agent modified nano titanium dioxide hybrid silica sol obtained by reaction of tetramethyldisiloxane and vinyltrimethoxysilane, so that the material is endowed with good flame retardant property, the ultraviolet protection property of the material is improved, and the mechanical property of the material is ensured.

The invention provides a zirconium boride / graphene complex-phase wear-resistant and high-temperature-resistant ceramic material and a preparation method thereof, and belongs to the technical field of ceramics. The preparation method comprises the following steps: pretreating graphene, preparing titanium dioxide / graphene microspheres, modifying the titanium dioxide / graphene microspheres, functionalizing the titanium dioxide / graphene microspheres, preparing a ceramic mixture, molding and sintering. The step of functionalizing the titanium dioxide / graphene microspheres comprises the following steps: putting the modified titanium dioxide / graphene microspheres into xylene, adding bisphenol A epoxy resin and triphenylphosphine, raising the temperature, carrying out stirring reaction, filtering out, washing, putting into N, N-dimethylformamide, uniformly stirring, adding gallic acid and p-toluenesulfonic acid, and carrying out ultrasonic treatment to obtain the titanium dioxide / graphene microspheres. Raising the temperature for reaction, filtering, washing and drying after the reaction is finished, so as to prepare functionalized titanium dioxide / graphene microspheres; the prepared ceramic material is high in strength, good in wear resistance and excellent in high temperature resistance.

The invention discloses an anti-static polyether-ether-ketone composite film as well as a preparation method and application thereof, relates to the technical field of electrostatic protection materials, and solves the problem of poor dispersity of single-form conductive fibers in a polyether-ether-ketone material in the prior art. The In2O3SnO2 (at) CF composite material with the multilayer porous structure and the superfine hollow structure is prepared through a spinning method and a solvothermal method, the specific surface area of the material is increased, and the conductivity is remarkably improved. The anti-static polyether-ether-ketone composite film is prepared by utilizing a method that indium and tin metal ions in the In2O3SnO2 (at) CF composite material can form stable coordinate bonds with amino groups and carboxyl groups in polyether-ether-ketone containing amino groups and carboxyl side groups, so that the interface bonding capacity between the In2O3SnO2 (at) CF composite material and the anti-static polyether-ether-ketone composite film is remarkably enhanced; the stability and the durability of the anti-static polyether-ether-ketone composite film are further improved. The anti-static film can be applied to preparation of anti-static films of integrated circuit chips and sensors in mobile phones or small electronic equipment.

The invention relates to the technical field of nano composite materials, and particularly discloses a super wear-resistant self-lubricating carbon nano polymer and a preparation process thereof. The invention discloses a super wear-resistant self-lubricating carbon nano polymer which is prepared from the following raw materials in parts by weight: 35-50 parts of phenolic resin, 5-10 parts of bisphenol F resin, 0.2-1 part of a defoaming agent, 5-10 parts of modified phenolic resin fiber, 1-1.5 parts of pretreated graphene, 5-10 parts of polytetrafluoroethylene, 12-18 parts of nano aluminum oxide, 6-10 parts of talcum powder, 0.5-3 parts of zirconium oxide, 0.2-1 part of a flatting agent and 1-5 parts of silicon carbide. 0.2-1 part of an antioxidant, 0.2-1 part of an ultraviolet absorbent and 25-35 parts of cardanol. The super-wear-resistant self-lubricating carbon nano polymer prepared by the invention has the advantages of good toughness and good wear resistance.

The invention discloses an in-situ synthesis Al2O3 reinforced low-density steel-based composite material and a preparation method of the in-situ synthesis Al2O3 reinforced low-density steel-based composite material. The in-situ synthesis Al2O3 reinforced low-density steel-based composite material comprises a steel matrix and an Al2O3 reinforced phase distributed in the steel matrix, the steel substrate is made of high-aluminum steel; the Al2O3 reinforced phase is generated by an in-situ reaction of an oxygen element in the metal oxide molten salt and an aluminum element in the high-aluminum steel melt in the smelting process, and the volume percent of the Al2O3 reinforced phase in the steel matrix is 10-20%. In the casting process, Al2O3 reinforced phase particles are generated in a steel matrix through in-situ reaction, good combination of the Al2O3 reinforced phase particles and the steel matrix is achieved, and the overall performance of the material is improved under the condition that the low density of the steel-based composite material is guaranteed.

The invention relates to bamboo fiber-based food fresh-keeping packaging paper and a preparation method thereof. The preparation method of the bamboo fiber-based food fresh-keeping packaging paper comprises the following steps: respectively grinding bleached sulfate tender moso bamboo fibers and moso bamboo root fibers, and dispersing and mixing to obtain NBF / BRF mixed pulp; then adding the modified moso bamboo cellulose nanocrystals to obtain NBF / BRF / BNC composite slurry; making paper with pulp, forming, dehydrating and drying to obtain a bamboo paper sample A, uniformly spraying bamboo vinegar on the outer surface of the bamboo paper sample A, and finally performing hot pressing and drying to obtain the bamboo fiber-based food fresh-keeping packaging paper. Bamboo fiber raw materials with different characteristics are used for preparing the packaging paper for food preservation, the bamboo fiber-based food packaging paper is endowed with excellent mechanical strength, barrier property, hydrophobic property and antibacterial and mildew-proof capabilities, and the bamboo fiber-based food packaging paper can be used in the field of packaging materials for fruit and vegetable preservation.

The invention provides an aluminum-based composite material reinforced by nickel-coated silicon carbide through a magnetron sputtering dry method and a preparation process of the aluminum-based composite material, and relates to the technical field of metal-based composite materials and advanced electronic packaging thermal management materials. Comprising the following steps that S1, silicon carbide particles coated with nickel through a magnetron sputtering dry method and aluminum powder are put into a mold to be subjected to compression molding, and an initial blank is obtained; and S2, the initial blank prepared in the step S1 is placed in a re-pressing sintering furnace under the inert gas protection condition, continuous re-pressing is conducted under the temperature condition ranging from the temperature lower than the aluminum melting point by 50 DEG C to the temperature higher than the aluminum melting point by 200 DEG C, and the nickel-coated silicon carbide reinforced aluminum-based composite material obtained through the magnetron sputtering dry method is obtained. The aluminum-based composite material reinforced by magnetron sputtering dry nickel-coated silicon carbide disclosed by the invention is excellent in heat-conducting property and mechanical property and long in service life.

The invention discloses a multilayer circuit board preparation method and system based on via hole filling optimization and a multilayer circuit board, and relates to the technical field of circuit board preparation, and the method comprises the steps: obtaining the size of a via hole, calculating the depth-to-width ratio, constructing a viscosity gradient function, taking a via hole filling quality evaluation index as a first optimization target, and solving an optimal ratio; designing a vacuum degree control strategy; the current capillary pressure is obtained, differential pressure driving force is calculated according to the current through hole gas pressure intensity, the time needed for filling and the preset ultrasonic vibration duration are calculated in combination with the through hole diameter, the hole depth and the viscosity gradient function, and ultrasonic auxiliary filling is carried out while through hole filling is carried out; filling the via hole, and controlling the vacuum degree according to the vacuum degree adjusting curve; and the real-time filling rate and the cavity volume are obtained, a second target function is constructed with the difference between the minimum target filling rate and the actual filling rate and the filling cost as a second optimization target, and the optimal filling step number and the optimal single injection material volume are solved.

The invention belongs to the technical field of cutter materials, and particularly relates to a nano-composite coating hard alloy cutter for intermetallic compound / high-temperature alloy machining and a preparation method of the nano-composite coating hard alloy cutter. An intermetallic compound / high-temperature alloy is a novel key material for aero-engines, is a difficult-to-process material, has high red hardness and good wear resistance, is easy to generate brittle fracture at high temperature, and is easy to generate thermal expansion and deformation in the processing process. Lanthanum-doped tungsten carbide and modified nickel powder are matched with other raw materials to prepare a novel hard alloy matrix, a boron nitride composite material and magnetic chitosan in the coating are matched, the hard alloy cutter is prepared, through the combined action of multiple components, the bending strength and hardness of the cutter material are effectively improved, and the service life of the cutter material is prolonged. Therefore, the good binding force between the coating and the matrix is enhanced.

The invention belongs to the technical field of ablation-resistant polymer-based composite materials, and particularly relates to an ablation-resistant modified sugar-based carbon fiber composite material and a preparation method thereof.The preparation method comprises the following steps that S1, carbon black filler particles are subjected to surface modification treatment; s2, preparing a glycosyl dipping solution; s3, impregnating the carbon fiber preform in a glycosyl impregnation solution in a vacuum environment, and performing pressure maintaining treatment to obtain a pre-impregnated carbon fiber preform; s4, performing gelatinization treatment on sweet water of the pre-impregnated carbon fiber preform in a vacuum drying oven to obtain a gelatinized carbon fiber preform; s5, performing two-stage low-temperature stabilization treatment on the gelatinized carbon fiber preform in a vacuum drying oven to obtain a stabilized carbon fiber preform; and step S6, performing high-temperature normal-pressure carbonization treatment on the stabilized carbon fiber preform in a protective atmosphere to obtain the ablation-resistant modified glycosyl carbon fiber composite material.

The invention belongs to the technical field of backfill materials, and particularly discloses a road shallow wet and soft foundation backfill material and a preparation method thereof. The road shallow wet and soft foundation backfill material is prepared from the following raw materials in parts by weight: 40 to 50 parts of building residue soil, 10 to 15 parts of modified diatomite, 15 to 20 parts of cement, 7 to 10 parts of modified chitosan, 60 to 70 parts of water and 5 to 9 parts of sodium carbonate. The road shallow wet and soft foundation backfill material prepared in the invention has relatively good strength, crack resistance and tensile strength, so that the bonding force between the building residue soil and other components is relatively good, and the structural strength and stability of the backfill material are improved.

The invention discloses a method for manufacturing a high-wear-resistant composite swing hammer head, which comprises the following steps: washing and drying ceramic particles with an oxalic acid solution, uniformly mixing boron carbide ceramic powder and an alcohol adhesive in proportion into a slurry, and drying to remove the alcohol adhesive; then mixing the ceramic particles with NiCrBSi powder and a sodium silicate solution and filling the mixture into a honeycomb mold, taking the mixture out after microwave curing, thereby obtaining a honeycomb ceramic preform with high strength at room temperature, wherein a conical preformed hole is formed on the honeycomb ceramic preform, placing the honeycomb ceramic preform into a casting cavity of a swing hammer head metal mold, and then pouring molten high-chromium cast iron into a runner of the casting mold, wherein the high-chromium cast iron water infiltrates into gaps between ceramic preform particles under high pressure to form a reactive interface, thereby obtaining a high-wear-resistant composite swing hammer head. The method can manufacture a composite swing hammer head with a reactive interface and high wear resistance.

The invention relates to the technical field of epoxy resin, in particular to an epoxy resin composition for high-strength carbon fiber winding and a preparation method thereof.The preparation method of the epoxy resin composition comprises the steps that S1, modified epoxy resin, a compatilizer, a retarder, a defoaming agent and nano filler are added into a reaction kettle and mixed and stirred, and a mixture A is obtained; s2, a composite curing agent is added into the mixture A, stirring and mixing are conducted, and the epoxy resin composition is obtained and has the advantages of being appropriate in viscosity, good in heat resistance, excellent in impact resistance, large in bending strength, small in volume shrinkage rate in the curing process, moderate in gelation time and capable of being wound with carbon fibers conveniently to prepare the composite material.

The invention provides a method for preparing austenite aging steel based on injection molding, and belongs to the technical field of steel materials. The modified raw materials such as the sulfur-carbon-molybdenum composite powder, the nitrogen-nickel composite powder and the boron-phosphorus-chromium composite powder are matched with the components such as the silicon powder, the manganese powder and the iron powder, the austenite aging steel is obtained through injection molding, the density of the austenite aging steel material is improved, and meanwhile the mechanical property and hardness of the austenite aging steel material are improved.

The invention discloses a tundish cover castable, and relates to the technical field of tundish refractory materials. The tundish cover castable is prepared from the following raw material components in percentage by mass: 7.8 to 9.6 percent of alumina of 8 to 5mm, 2.6 to 4.3 percent of alumina of 5 to 3mm, 2.6 to 4.3 percent of alumina of 1 to 0mm, 17.4 to 20.8 percent of alumina of 200 meshes, 9.6 to 13 percent of mullite of 5 to 3mm, 22.6 to 26 percent of mullite of 3 to 1mm, 9.6 to 13 percent of mullite of 1 to 0mm, 7 to 8.7 percent of mullite of 200 meshes, 2.6 to 3.5 percent of composite binding agent, 0.8 to 1.7 percent of aluminum silicate, 0.05 to 0.07 percent of SiC nanowire, 0.2 to 0.3 percent of aluminum titanate and the balance of water. The invention discloses a tundish cover castable which comprises the following components in percentage by weight: 0.4-0.7% of alumina micro powder, 0.08-0.11% of sodium tripolyphosphate, 2.6-3.5% of silica fume, 0.87% of steel fiber and 1.3-1.7% of high-alumina cement. Compared with a traditional process, the tundish cover castable has the advantages that the overall performance of the tundish cover castable is remarkably improved, the breaking strength and compression strength of the castable are effectively enhanced, the service life is remarkably prolonged, and the production cost is reduced. And the production cost is greatly saved, and the economical efficiency and the operation rate of continuous casting operation are improved.

The invention relates to the technical field of high polymer materials, and particularly discloses a nano-silica synergistic flame-retardant polypropylene composite material and a preparation method thereof, and the nano-silica synergistic flame-retardant polypropylene composite material comprises the following components in parts by mass: 50-70 parts of PP resin, 10-20 parts of a flame retardant, 2-8 parts of a flame-retardant synergist, 1-5 parts of a flow modifier, 0.2-0.8 part of an anti-dripping agent and 0.5-2 parts of an antioxidant. Compared with the prior art, the flame-retardant polypropylene composite material has the beneficial effects that the prepared flame-retardant polypropylene composite material has excellent performance in tensile strength, elongation at break, bending strength, impact strength, melt index and limit oxygen index.

The invention relates to the technical field of batteries, in particular to a surface-modified positive electrode material and a surface modification method thereof. The positive electrode material surface modification method provided by the invention comprises the following steps: S1, mixing a cobalt source with an organic solvent to obtain an intermediate, and depositing the intermediate on a graphite sheet by adopting a chemical deposition method to obtain a coating material; and S2, mixing the positive electrode material with the coating material obtained in the step S1, and calcining to obtain the surface-modified positive electrode material. According to the invention, the cobalt source is deposited on the graphite flake through a chemical deposition method to form the graphite flake of which the surface is uniformly coated with cobalt hydroxide, so that not only can the stability of the coating material structure be improved, but also the electrochemical activity of cobalt hydroxide in the coating material can be further improved; the graphite flake with cobalt hydroxide deposited on the surface is used as a coating material to be sintered with the positive electrode material, so that the obtained surface-modified positive electrode material is good in structural stability and high in specific capacity, and the cycle retention rate of the battery can be improved.

The invention discloses a method for preparing a metal casting mold based on steel grit 3D printing, and belongs to the technical field of metal casting mold machining. In order to solve the technical problem that in the prior art, the mechanical strength and collapsibility of a metal casting mold need to be further improved, the method for preparing the metal casting mold based on steel grit 3D printing comprises the following steps that a sand mold three-dimensional model is established according to a metal casting, then casting mold steel grit is filled in an operation box of sand mold 3D printing equipment, and the casting mold steel grit is obtained; the binder storage tank is filled with a binder; and according to the section formation of the sand mold three-dimensional model, a sand paving system of the sand mold 3D printing equipment paves cast steel sand on a printing platform. The casting steel sand and the binder are matched with each other, the metal casting mold blank is prepared through 3D printing and then dried, the normal-temperature mechanical property and high-temperature property of the metal casting mold are effectively improved, the application range of the metal casting mold is widened, and meanwhile the collapsibility of the metal casting mold is improved.