695 results about "Oxidation resistance" patented technology

The invention discloses a graphite piece silicon carbide coating and a preparation method thereof, and belongs to the technical field of inorganic non-metallic materials. The method comprises the following steps: firstly, carrying out surface polishing, cleaning and drying pretreatment on a graphite piece; then a solution containing phosphinazine functionalized silazane and a boron-silicon carlamide compound is adopted for spraying the pretreated graphite piece, drying and curing are conducted, and a surface modification layer is formed; and finally, placing the surface-modified graphite piece in chemical vapor deposition equipment, and depositing at specific temperature, pressure and atmosphere to form the silicon carbide coating. According to the method, uniform nucleation and crystallization of the silicon carbide coating are effectively promoted through unique surface modification treatment, and the compactness and uniformity of the coating and the binding force of the coating and a matrix are remarkably improved. The obtained coating graphite piece has excellent thermal corrosion resistance, oxidation resistance and mechanical property, the service life and the use frequency of the coating graphite piece in semiconductor epitaxial equipment are remarkably prolonged, the whole preparation process is environmentally friendly, and the coating graphite piece is suitable for coating treatment of a large graphite base material.

The invention discloses a rare earth metal ceramic and a preparation method thereof, and belongs to the technical field of metal ceramic preparation, the rare earth metal ceramic comprises, by mass, 45-65% of a ceramic phase, 30-50% of a metal binding phase and 3-8% of a rare earth additive, the ceramic phase is composed of one of TiC and WC and one of Al2O3 and ZrO2, the metal binding phase is composed of a Ni-Co alloy and Mo or Cr, and the rare earth additive is composed of one of Al2O3 and ZrO2. The rare earth additive is composed of mixed rare earth oxide and nano rare earth fluoride. The invention further provides a preparation method of the rare earth additive. Through the synergistic effect of oxide grain boundary purification and fluoride liquid phase sintering in a two-phase rare earth system, the problem that traditional single rare earth is difficult to add and disperse is solved, through staged hot pressing sintering, dual optimization of grain refinement and density improvement is achieved, and the high-temperature oxidation resistance and interface bonding strength of metal ceramic are enhanced.

The invention relates to the technical field of coated cutting tools, and provides a nano multilayer structure coated cutting tool and a preparation method thereof.The nano multilayer structure coated cutting tool comprises a base body and a nano multilayer structure coating deposited on the surface of the base body through a physical vapor deposition method, and the coating sequentially comprises a WC coating deposited on the base body, a WC coating deposited on the surface of the base body, a WC coating deposited on the surface of the base body and a WC coating deposited on the surface of the base The first CrCN / WC functional layer is composed of a first CrCN nano layer and a first WC nano layer which are alternately deposited; the second CrCN / WC functional layer is composed of a second CrCN nano layer and a second WC nano layer which are alternately deposited; the CrTaHfCN / CrCN / WC functional layer is formed by periodically and repeatedly depositing a first CrTaHfCN nano layer, a third CrCN nano layer and a third WC layer according to an ABC sequence; and a CrTaHfCN surface layer. According to the invention, the bonding strength between the layers is improved, and the oxidation resistance, high temperature resistance, wear resistance and crack propagation resistance of the coating are obviously improved.

The invention relates to the technical field of surface protective coatings, in particular to a preparation method of a diffusion coating based on rare earth oxide modification, which comprises the steps of matrix pretreatment, permeation agent preparation and coating preparation. The permeation agent is composed of an aluminum supply agent, a filling agent, an activating agent and a permeation accelerating agent, wherein nano cerium oxide serves as the permeation accelerating agent and can remarkably improve the coating performance. By optimizing process parameters, the aluminizing temperature is reduced to 630 DEG C, and the time is shortened to be within 5 hours. The oxidation resistance, the hot corrosion resistance and the matrix bonding strength of the coating can be remarkably improved, and the coating is suitable for TiAl intermetallic compounds and other high-temperature alloy materials and has wide application prospects in the fields of aerospace and the like.

The invention relates to the technical field of deposition of wear-resistant and corrosion-resistant coating materials on metal surfaces, in particular to a high-toughness CrNbZrNiSiBN high-entropy nitride coating and a preparation method thereof. A bonding layer formed by a Cr layer, a transition layer formed by a CrN layer and a functional layer coated with CrNbZrNiSiBN high-entropy nitride are sequentially arranged on the surface of a base material. And the total thickness of the coated functional layer is 2-10 microns. The method is completed by adopting an ion beam assisted arc ion plating technology, and the prepared composite coating has the advantages of relatively high hardness, relatively good toughness, wear resistance, corrosion resistance, high-temperature oxidation resistance and the like. The coating can be used for strengthening and protecting the surfaces of cutters, molds, aerospace, marine ship parts and the like.

The invention provides a method for preparing a zirconium boride ceramic material through pressureless sintering, and belongs to the technical field of zirconium boride ceramics. The method comprises the steps of preparing zirconium boride composite powder, modifying silicon carbide nanowires and mixing and sintering. The method for modifying the silicon carbide nanowire comprises the steps of acid treatment and modification, the modification step comprises the following steps: adding aluminum isopropoxide into absolute ethyl alcohol, adding a nitric acid solution, stirring for 1.5-2.0 hours at the temperature of 60-63 DEG C, adding the acid-treated silicon carbide nanowire, carrying out ultrasonic dispersion and water bath evaporation, then drying, putting into a muffle furnace, and carrying out heat preservation for 2.0-2.2 hours at the temperature of 490-500 DEG C to obtain a modified silicon carbide nanowire; the ceramic material prepared by adopting the method disclosed by the invention is high in density, good in mechanical property and excellent in high-temperature oxidation resistance and stability in a complex environment.

An austenitic Fe—Ni—Cr alloy has superior oxidation resistance even under extreme high temperatures and includes, in mass %: C: 0.004 to 0.13%, Si: 0.15 to 1.0%, Mn: 0.03 to 2.0%, P:≤0.040%, S:≤0.003%, Ni: 20.0 to 38.0%, Cr: 18.0 to 28.0%, Mo:≤1.0%, Cu:≤1.0%, N:≤0.03%, B:≤0.01%, Al: 0.10 to 1.0%, at least one of Ti: 0.10 to 1.0% and Zr: 0.01 to 0.6%, O: 0.0002 to 0.0030%, Ca:<0.002%, total weight of one or more from La, Ce, and Y: 0.001 to 0.010%, Fe as a remainder and inevitable impurities, and wherein the chemical composition satisfies formulae (1) and (2): 85≥0.3×Si+1.5×Ni+1.3×Cr+5.8×Al+7.7×Zr +2.7×Ti+2173×REM −3582×S ×32.9×Mo -2448×B≥47 . . . (1) 40≥0.6×Si+1.3×Cr +23.53×Al+5.88×Ti+3074×REM −5067×S −0.8×Mn −816×N≥. . . (2), and each element symbols indicates content of each element.

The invention discloses high-conductivity low-temperature sintering composite copper paste and a preparation method and application thereof, and belongs to the technical field of conductive paste. The composite copper paste consists of the following components in percentage by mass: 70-90% of a conductive phase, 2-10% of a binding phase and the balance of an organic carrier. Wherein the conductive phase comprises cuprous hydride modified copper powder and a copper complex; the copper complex is formed by a copper compound and an organic ligand through a coordination reaction. The copper paste can be sintered to form an electrode or a circuit in a nitrogen atmosphere at a temperature of less than or equal to 300 DEG C, and has the advantages of low resistivity, good oxidation resistance, strong adhesion and the like, and the cost of the copper paste is obviously lower than that of silver paste. The invention also provides a preparation method of the composite copper paste and an application of the composite copper paste in preparation of an electronic component electrode or a conductive circuit.

The invention discloses hollow silver-coated copper particles and a preparation method and application thereof, and belongs to the technical field of conductive material preparation. Through the unique hollow silver-coated copper particle structure design and the optimized preparation method, the use amount of silver is effectively reduced, and the cost is reduced; meanwhile, the compact silver layer and the surface modification layer can achieve a synergistic effect, so that the oxidation resistance, the conductivity and the dispersity of the hollow silver-coated copper particles are remarkably improved, the hollow silver-coated copper particles have more excellent application performance, the prepared conductive paste is endowed with excellent performance, and the conductive paste is suitable for various curing modes and has good application prospects. The method has a wide application prospect in the fields of photovoltaics, flexible electronics and the like, and is suitable for large-scale production.

The application belongs to the technical field of welding materials, and discloses a preformed soldering sheet and a preparation method thereof, the preparation method comprising: a flux preparation method, wherein benocyclobutene resin, a thixotropic agent, an active agent, a surfactant, an antioxidant, a corrosion inhibitor and a solvent are weighed, mixed and heated and stirred to mix, and then cooled to obtain the required flux; a processing method of a preformed soldering sheet body soldering strip, wherein lead-free filler metal is melted at high temperature to form a soldering strip; and a preformed soldering sheet preparation method, wherein the soldering strip is uniformly coated with the flux by a coating machine, and the flux is cured and attached to the soldering strip after baking; the preformed soldering sheet is obtained by the above preparation method. The application realizes improved welding quality of the soldering sheet coated with the flux film and solder metal oxidation resistance, and the preformed soldering sheet has high stability, good wettability and good weldability, and can meet the requirements of the market for the use of the preformed soldering sheet with low cavities.

The invention discloses a hard coating with thermal stability and high-temperature oxidation resistance as well as a preparation method and application of the hard coating, and belongs to the technical field of nitride hard coatings. The hard coating is composed of a bottom columnar crystal TiAlN base coat, a middle columnar crystal AlTiCrN middle layer and an AlCrSiBN surface layer of a surface nanometer composite structure. Low-aluminum TiAl target deposition is adopted for the TiAlN base layer, high-aluminum AlTi target and AlCr target co-deposition is adopted for the middle of the TiAlN base layer, and high-aluminum AlCrSiB target deposition is adopted for the AlCrSiBN surface layer; the thickness of the TiAlN base coat is 0.1 to 0.5 [mu] m; the thickness of the AlTiCrN intermediate layer is 1.0 to 2.0 [mu] m; and the thickness of the AlCrSiBN surface layer is 0.05 to 0.2 [mu] m. The coating has high film-substrate binding force, thermal stability and high-temperature oxidation resistance. The inner layer of the coating has excellent thermal stability, and the outer layer of the coating has excellent high-temperature oxidation resistance, so that the coating has wide application prospects on the surfaces of products such as cutting tools and molds.

The invention discloses a preparation method of low-temperature solderable conductive copper paste, and belongs to the technical field of electronic materials. The conductive copper paste is prepared from the following raw materials: silver-coated copper powder, an organic carrier, an antioxidant, a curing agent, an auxiliary agent, a thixotropic agent, a solvent and an adhesion enhancer. The design of the composite copper powder coated with the silver layer on the surface is matched with the graded particle size, and an organic carrier is combined, so that high conductivity and strong oxidation resistance under low-temperature curing are realized. The preparation method comprises the following steps: treating the copper powder by adopting a dipping-drying process, and coating the surface of the copper powder with the adhesion enhancer and the antioxidant by adopting a chemical method; uniformly mixing the organic carrier, the curing agent, the solvent and the auxiliary agent; and finally, copper powder and a thixotropic agent are added into the mixed organic carrier, and the low-temperature solderable conductive copper paste is prepared through high-speed dispersion and grinding of a three-roller machine. The product can be rapidly cured at 100-180 DEG C, the sheet resistance is smaller than or equal to 20 m omega / square, the welding strength reaches 15 MPa or above, cost is low, production is easy, and wide industrial application value is achieved.

The invention discloses a nano reinforcing agent for a modified epoxy powder coating and a preparation method of the nano reinforcing agent, and relates to the technical field of coating materials. According to the invention, through a core-shell-dendritic hybrid structure, different core materials are matched with a shell layer material, and chemical bond directional connection is adopted, so that the nano filler is uniformly dispersed, the problem of agglomeration of a traditional nano material is solved, and meanwhile, high thermal conductivity and antistatic synergism and efficient self-repairing capability are achieved, and a better electrostatic spraying effect is achieved; by adding the nano reinforcing agent with high strength and rigidity, the hardness, impact resistance and wear resistance of the coating can be remarkably improved, so that the service life of the coating is prolonged, and the stability of the coating is improved; due to the design of the nano reinforcing agent and surface functionalization treatment, the hydrophobicity and chemical stability of the coating can be improved, permeation of water and chemical substances is effectively prevented, the corrosion resistance of the coating is enhanced, and the service life of the coating is prolonged.

This invention discloses a method for preparing ultrafine spherical silver-coated copper powder. A dense film is formed on the surface of copper powder using a specific activator, and this film can quickly form a complex with silver ions in the solution. At the same time, under the action of a specific reducing agent, silver ions are reduced to fine silver nanoparticles and adsorbed on the surface of copper powder. Silver ions in the solution form a dense silver layer on the surface of copper powder through two-dimensional nucleation, resulting in silver-coated copper powder with high density, high conductivity, and high oxidation resistance.

The utility model belongs to the field of door and window sealing strips, and particularly relates to a high-sealing dustproof sealing strip which comprises a sealing strip body, the sealing strip body comprises a limiting shell, an adhesive layer is arranged at the bottom of the limiting shell, and an arc-shaped sealing gasket is arranged in an inner cavity of the limiting shell. The anti-cracking performance and the anti-freezing performance of the sealing strip body can be improved through the protective layer, the high-temperature resistance and the corrosion resistance of the sealing strip body are improved through the reinforcing layer, the oxidation resistance and the abrasion resistance of the sealing strip body are improved through the protective layer, and the sealing strip body is prevented from being abraded due to opening and closing of doors and windows; therefore, the sealing and dustproof performance of the sealing strip body is improved, and the problems that an existing sealing strip is usually installed in a door and window frame, due to the fact that a door and a window are opened and closed frequently, the sealing strip is prone to being abraded, and the sealing and dustproof performance of the sealing strip becomes poor are solved. And the durability and the service life of the sealing strip are improved and prolonged by utilizing good flexibility and weather resistance of the material.

The invention discloses a low-corrosion halogen-free soldering flux for aluminum-based part brazing and a preparation method of the low-corrosion halogen-free soldering flux, and belongs to the technical field of halogen-free welding materials.The low-corrosion halogen-free soldering flux comprises, by mass, 4-6 parts of oxalic acid, 1-2 parts of triethanolamine, 0.8-1.5 parts of Tween-80, 4-6 parts of polyvinylpyrrolidone, 0.3-1 part of compound nano cerium oxide, 0.5-1.5 parts of chitosan oligomer and the balance deionized water. And the welding spot oxidation resistance and the interface self-repairing capability are further improved. Through the synergistic effect of four mechanisms of complexing, oxidation prevention, wetting and film forming, the flux achieves efficient film removal, excellent wetting, no corrosion residue and stable film forming protection, is high in shear strength, low in welding spot porosity and clean in surface after welding, and is suitable for electronic packaging, heat exchanger manufacturing and high-reliability aluminum welding occasions.

The invention discloses an acoustic resonance assisted nano-SiO2 coated flaky carbonyl iron powder as well as a preparation method and application thereof, the flaky carbonyl iron powder is taken as a main raw material, an acoustic resonance assisted modification technology is adopted, a compact and uniform SiO2 coating layer is constructed on the surface of the flaky carbonyl iron powder, and an FCIP coated SiO2 composite material with a core-shell structure is prepared. According to the coating treatment, the oxidation resistance and corrosion resistance of the carbonyl iron powder are remarkably improved, electromagnetic parameters of the carbonyl iron powder are regulated and controlled, and particularly the wave absorbing performance of the material in a low-frequency wave band is enhanced. An electromagnetic parameter test and reflection loss calculation show that the obtained composite material has better impedance matching characteristics and lower reflection loss value. In practical application, a coated sample shows higher thermal stability and lower surface corrosion rate, and the service life of the material in a complex service environment is effectively prolonged. The method is simple and convenient in process, low in cost and suitable for being applied to functional material systems such as electric conduction, wave absorption and electromagnetic interference prevention on a large scale.

The invention belongs to the technical field of high polymer materials, and particularly relates to a high-strength plastic film and a preparation method thereof. The high-strength plastic film is prepared from the following raw materials in parts by weight: 80 to 90 parts of polylactic acid, 5 to 10 parts of polyurethane resin, 2 to 6 parts of flame-retardant modified halloysite, 2 to 6 parts of antioxidant modified halloysite, 0.5 to 2 parts of silane coupling agent and 1 to 3 parts of plasticizer. According to the invention, the halloysite is subjected to flame-retardant modification and antioxidant modification and is added into a PLA matrix, so that the halloysite can be used as an inorganic filler to reinforce the rigidity and strength of the PLA matrix, and also has flame-retardant and antioxidant dual functions; meanwhile, the tubular structure of the halloysite nanotube can form a zigzag path in a PLA matrix, so that diffusion of water vapor and oxygen is delayed, the water vapor permeation amount and the oxygen permeation coefficient are reduced, and the halloysite nanotube can be applied to food packaging to prolong the fresh-keeping period of food.

The invention belongs to the technical field of data center cooling, and discloses a narrow fraction mineral base oil single-phase immersed cooling liquid and a preparation method thereof in order to solve the problem of poor stability of the cooling liquid, and the preparation method comprises the following steps: preparing a dispersant; the preparation method comprises the following steps: adding an antioxidant and nano heat-conducting particles into narrow fraction mineral base oil, and stirring to obtain a product a; heating narrow fraction mineral base oil, adding a dispersing agent and an anti-rust agent, and stirring to obtain a product b; and finally mixing and stirring the product a and the product b. The cooling liquid provided by the invention takes the narrow fraction mineral base oil as a matrix, solves the problems of poor heat dissipation, weak oxidation resistance and low flash point of the traditional mineral oil through the synergistic effect of all the components, has low viscosity, high flash point, excellent electrical insulation and thermal conductivity, good compatibility and low volatilization rate, is suitable for immersed cooling systems such as a large computing power data center, and has wide application prospects. The high-efficiency heat dissipation and safe operation requirements of high-heat-density equipment can be met, the preparation process is simple, the cost is low, and the industrial application value is good.

The invention relates to a high-temperature-resistant reusable self-aligning roller bearing, and belongs to the technical field of bearings. A roller is arranged between an inner ring and an outer ring, and the inner ring is made of Al0. 5CrCoFeW0. 5Ni high-entropy alloy; the oxidation resistance, the strength, the stability and the wear resistance during working are met; the outer side surface of the inner ring is subjected to ion implantation modification to form a modified layer of the inner ring; the TiAlN coating reduces energy loss, and the first Ag coating is used for conducting heat and reducing oxidation loss; the outer ring is made of an Al < 0.5 > CoCrFeV < 0.5 > Ni high-entropy alloy; the high bearing capacity, the wear resistance, the fatigue resistance, the dimensional stability and the corrosion resistance in the working process are met; the modified layer on the inner side surface of the outer ring is used for improving the surface hardness and enhancing the wear resistance; the CrAlN coating is used for improving oxidation resistance, and the second Ag coating is used for conducting heat and reducing oxidation loss; the roller is made of an AlCoCrFeNi2. 1Nb0. 6 high-entropy alloy; a lubricating structure on the surface of the roller comprises an annular groove and graphite fluoride; a lubricating film is formed when the raceway and the roller rub each other, and the integrity of the lubricating film is maintained.

The invention belongs to the technical field of coating materials, and particularly relates to a self-repairing environmental barrier coating as well as a preparation method and application thereof. The self-repairing environmental barrier coating comprises a first coating, a second coating and a third coating, the first coating is a coating containing Ta2O5, the second coating is an R2Si2O7-MeSi2 composite coating, R is selected from at least one of Yb, Y, Gd, Lu, Nd and Ta, Me is selected from at least one of Mo, Ta and Yb, and the third coating is a PrMgAl11O19 coating. The first coating, the second coating and the third coating are sequentially laminated on the base body; the thermal expansion coefficient of the first coating, the thermal expansion coefficient of the second coating and the thermal expansion coefficient of the third coating are distributed in a gradient increasing mode. The self-repairing environmental barrier coating disclosed by the invention still has high bending strength retention rate, relatively long high and low temperature cycle service life and oxidation resistance in a high-temperature service process.

The present invention relates to a method for manufacturing a part (1) with improved resistance to oxidation and high-temperature corrosion, comprising at least the deposition of a non-cracked crystalline β-Yb2Si2O7 environmental barrier layer (7) on an at least partially ceramic matrix composite material (3), wherein the environmental barrier layer is deposited by chemical vapour deposition from a gas phase comprising a precursor mixture of (a) a compound A of formula SiClxHy, in which x is an integer from 1 to 4 and y is an integer from 0 to 3, with x + y = 4, and (b) elementary ytterbium or ytterbium(III) chloride, and wherein, during deposition, a temperature between 1100°C and 1300°C and a pressure of 150 mbar or less are imposed.

The invention belongs to the technical field of cable sheath materials, and provides a ceramic silicone rubber sheath material and a preparation method and application thereof. Polycarbosilane is subjected to staged heat treatment, so that the polycarbosilane is crosslinked, pyrolyzed and ceramized to obtain SiOC powder, and the SiOC powder has excellent crack resistance and heat stability; boric acid and phosphate are mixed and then are subjected to high-temperature melting and rapid cooling, borophosphate glass powder is prepared, the low-temperature softening characteristic of the borophosphate glass powder can fill pores in the ceramization process, and the compactness and mechanical performance of a ceramic layer are improved; molybdenum powder and silicon powder are mixed, and molybdenum disilicide powder is prepared through high-temperature reaction, so that the oxidation resistance of the material is improved; methyl vinyl silicone rubber is uniformly mixed with SiOC powder, borophosphate glass powder and molybdenum disilicide powder in sequence, a vulcanizing agent, an antioxidant and an auxiliary agent are added, the ceramic silicone rubber sheath material is prepared through a vulcanization process, and the material has excellent fire resistance at high temperature.

The invention discloses a high-strength polyethylene film and a preparation method thereof, and relates to the technical field of high polymer materials. The invention discloses a high-strength polyethylene film. The high-density polyethylene composite material comprises the following raw materials in parts by weight: 40-60 parts of high-density polyethylene, 13-25 parts of low-density polyethylene, 5-10 parts of an ethylene-vinyl alcohol copolymer, 10-15 parts of modified nano calcium carbonate, 3-5 parts of modified lignin fibers, 0.5-1 part of an antioxidant 1010, 0.3-0.7 part of a light stabilizer 770, 1-2 parts of zinc stearate and 2-3 parts of maleic anhydride grafted polyethylene. The coating comprises, by weight, 20-30 parts of polyethylene glycol terephthalate, 3-5 parts of poly (butylene adipate-co-butylene terephthalate), 2-4 parts of talcum powder, 1-3 parts of polymethyl methacrylate and 30-45 parts of deionized water. The high-strength polyethylene film is scientific in raw material ratio, and contains various modified components to enhance the performance; the modified nano calcium carbonate and lignin fiber technology is advanced, and compatibility and stability are improved; the preparation method is reasonable, and the film has the characteristics of high strength, good toughness, oxidation resistance, light resistance and the like and is wide in application through two-way stretching and other procedures.

The invention discloses an SLM (selective laser melting) forming method of an In718 high-temperature alloy material, which comprises the following steps: selecting 15-35 mu m spherical powder, and carrying out ultrasonic screening, plasma activation and 50-100nm aluminum oxide coating modification to improve wettability and oxidation resistance; in an inert gas cabin, a platform is preheated at the temperature of 100-150 DEG C, and a pre-tightening layer with the density larger than or equal to 98% is formed through vibration auxiliary powder laying; a pulse fiber laser is adopted to dynamically modulate parameters, a thin-wall area and a solid area are matched with a spiral scanning path, and the cooling rate of a molten pool is reduced by 30%-50%; a molten pool is monitored through dual-wavelength infrared temperature measurement and a high-speed CCD, and laser frequency compensation and argon blowing stable convection are triggered; constructing a three-layer temperature gradient; by means of the method, the density and the high-temperature performance of the formed part are improved, and the method is suitable for manufacturing of aerospace complex structural parts.

The invention relates to the technical field of composite metal materials, in particular to a silver-coated graphene copper composite material and a preparation method thereof, and aims at solving the problems that traditional silver-coated copper powder is high in silver consumption, copper is oxidized due to the fact that a silver layer is prone to being damaged, and conductivity is insufficient. The method comprises the steps that a graphene coating layer is formed on a copper powder substrate in situ through chemical vapor deposition, and graphene copper powder is obtained; performing etching treatment on the graphene copper powder to controllably expose part of the copper substrate so as to form anchoring points for silver ion deposition; carrying out reduction treatment on the etched graphene copper powder so as to ensure that an anchoring site has chemical activity; in a reductive liquid phase environment, enabling a chemical silver plating solution to react with the graphene copper powder subjected to reduction treatment, and guiding silver ion deposition by utilizing an anchoring point, so as to form a silver coating layer on the surface of the graphene coating layer; and separating and drying the reacted system to obtain the silver-coated graphene copper composite material. The material is better in oxidation resistance and conductivity, and the process is free of waste liquid.

According to the silicon carbide / diamond multi-layer composite film and the preparation method thereof, a polycrystalline silicon carbide matrix in the multi-layer composite film is a bottom layer, and the multi-layer composite film has high strength, high rigidity, high heat conductivity and oxidation resistance; the components of the gradient SiC-C transition layer gradually change from pure SiC to rich C-SiC and then to diamond-like carbon, and the gradient SiC-C transition layer is used for slowly releasing thermal stress and enhancing binding force; the nanocrystalline diamond is used as the top layer and has high hardness, low friction coefficient, particle scouring resistance and high infrared transmittance; the silicon carbide / diamond multi-layer composite film is obtained through a chemical vapor deposition method, the process is mature, and the silicon carbide / diamond multi-layer composite film has good heat conduction performance and infrared transmittance and is suitable for infrared guidance systems with extremely severe working environments, such as optical materials of fairings, optical windows and the like.

The invention discloses a tungsten-containing ultrahigh-temperature high-entropy rare earth boride ceramic material as well as a preparation method and application thereof. The preparation method of the tungsten-containing ultrahigh-temperature high-entropy rare earth boride ceramic material comprises the following steps: 1) preparing a green body from metal oxide powder and boron carbide powder; 2) performing electric field sintering, crushing and screening on the green body to prepare tungsten-containing ultrahigh-temperature high-entropy rare earth boride ceramic powder; and 3) pressing the tungsten-containing ultrahigh-temperature high-entropy rare earth boride ceramic powder into a green body, and then carrying out spark plasma sintering. The tungsten-containing ultra-high-temperature high-entropy rare earth boride ceramic material has excellent ultra-high-temperature oxidation resistance, is wide in component space range and low in cost, has a very wide application prospect in ultra-high-temperature thermal protection components such as the leading edge, the nose cone and the control surface of a hypersonic aircraft, and has a wide application prospect. And the preparation method has the advantages of simple operation and process flow, short reaction time, low synthesis cost and the like, and is suitable for large-scale industrial production.

The invention relates to shot-blasting-free treatment liquid for zinc-based coating hot forming steel, a preparation method and application of the shot-blasting-free treatment liquid, and relates to the technical field of steelmaking. Wherein the shot-blasting-free treatment liquid comprises 95 to 98 parts of a solvent; the composition comprises the following components in parts by weight: 0.2 to 0.3 part of an organic modifier, 1 to 4 parts of an inorganic film-forming agent, 0.1 to 0.4 part of an organic chelating agent, 0.2 to 0.4 part of a stabilizer, and 0.1 to 0.3 part of a surface improving agent. The shot-blasting-free treatment liquid forms a compact and uniform composite protective film on the surface of zinc-based coating steel. The protective film is converted into an inert layer with high-temperature oxidation resistance in the heat treatment process, and contact between oxygen and a zinc coating is effectively blocked, so that oxidation and volatilization of zinc at high temperature are remarkably reduced, the generation amount of ZnO and the loss of zinc element are reduced, the protective effect of the coating in the heat forming process is ensured, and the service life of the coating is prolonged. The product treated by the shot-blasting-free treatment liquid and processed by the hot forming process is clean in surface, controllable in surface oxidation product and free of an additional shot-blasting process.

The invention discloses a preparation method of high-oxidation-resistance silver-coated copper composite powder, which comprises the following steps: (1) pretreatment of copper powder: sequentially putting the copper powder into alkali liquor and acid liquor for pretreatment to obtain the pretreated copper powder; (2) preparation of copper powder suspension: dispersing the pretreated copper powder in a mixed solvent of water and alcohol, then adding a dispersing agent, a reducing agent and a surface tension additive, and adjusting the pH value to 9-11 to obtain the copper powder suspension; and (3) a coating reaction is conducted, specifically, the silver complex solution is dropwise added into the copper powder suspension obtained in the step (2) for the coating reaction, the reaction continues to be sufficient after dropwise adding is completed, the high-oxidation-resistance silver-coated copper composite powder is obtained, and the thickness of a silver coating layer is 150-200 nm. The prepared silver-coated copper composite powder has the advantages of being good in dispersity, uniform and compact in silver coating layer and high in oxidation resistance.