25results about How to "Avoid abnormal growth" patented technology

The invention discloses a silver-coated copper powder preparation method based on nickel layer enhanced palladium catalysis and active hydrogen synergistic deposition, and relates to the technical field of powder surface treatment. The method specifically comprises the following steps that copper powder is soaked in acid liquor, then filtering, washing and drying are conducted, and pretreated copper powder is obtained; immersing the pretreated copper powder into a hydrochloric acid solution of nickel chloride hexahydrate, and then filtering, washing and drying to obtain sensitized copper powder; immersing the sensitized copper powder into a hydrochloric acid solution of palladium chloride, and then filtering, washing and drying to obtain activated copper powder; mixing the activated copper powder with the reduction solution to obtain a solid-liquid mixture, adding a silver-ammonia solution into the solid-liquid mixture, heating for reaction, and filtering after the reaction is finished to obtain a solid product; and washing and drying the solid product to obtain the silver-coated copper powder based on nickel layer enhanced palladium catalysis and active hydrogen synergistic deposition. The silver-coated copper powder with a compact silver layer and high binding force is prepared through the ternary synergistic effect of nickel layer sensitization, palladium nanometer activation and formaldehyde reduction.

This invention discloses a method for preparing silicon carbide fibers with an in-situ boron nitride coating. The method involves melt spinning a metal-doped polycarbosilane precursor to obtain doped polycarbosilane precursor fibers. These precursor fibers are then subjected to a non-melting treatment in an oxidizing atmosphere to obtain non-melting fibers. The non-melting fibers are then subjected to inorganic pyrolysis to obtain inorganic fibers. These inorganic fibers are then densified and sintered to obtain boron-containing SiC fibers. Finally, the boron-containing SiC fibers are subjected to high-temperature treatment in a nitrogen atmosphere to obtain silicon carbide fibers with an in-situ boron nitride coating. This invention provides a simple preparation method, resulting in an in-situ self-grown BN coating with high crystallinity, good stability, and excellent uniformity. The coating is tightly bonded to the SiC fibers, is low-cost, and can be mass-produced. Furthermore, it significantly improves the fiber's temperature resistance and high-temperature creep resistance, allowing the fiber to serve for extended periods at higher temperatures.

This invention discloses a two-step oscillating hot-pressing sintering method for WC-Co cemented carbide. Specifically, the method involves: loading WC-Co cemented carbide mixed powder into a mold and pre-pressing it; firstly, holding the powder at 800°C in a vacuum environment to degas and pre-sinter the billet; then applying unidirectional oscillating pressure to the billet through the mold and raising the temperature to 1100°C for solid-state sintering. Dynamic pressure causes WC particles to rearrange, and Co particles undergo severe plastic deformation under the pressure of the WC particles, further increasing the relative density of the billet; finally, the temperature is raised to 1300-1350°C to form a WC-Co eutectic liquid phase. Dynamic pressure drives further particle rearrangement, and the eutectic liquid phase uniformly fills the gaps between WC particles, completing the sintering process. This invention improves the three-dimensional spatial distribution uniformity of the Co phase, eliminates residual porosity, effectively inhibits abnormal growth of WC grains, and produces cemented carbide with excellent strength and toughness.

This invention relates to the field of high-temperature alloy investment casting technology, and discloses an inert ceramic core for high-temperature alloy hollow castings and its preparation method. The preparation method includes the following steps: using yttrium-stabilized zirconia as the matrix material, yttrium oxide powder as a mineralizer, alumina-toughened zirconia powder as a toughening agent, yttrium aluminum garnet powder as an additive, and thorium oxide as a grain inhibitor, the above powders are mixed evenly, a paraffin-based plasticizer is added, and the mixture is vacuum stirred to form a slurry with fluidity and thermoplasticity; the slurry is added to a hot-pressing core-casting machine, and a core blank is prepared using the hot-pressing method; the core blank is embedded with sand and then sintered at high temperature, and cleaned after sintering to obtain the ceramic core. This invention improves the chemical inertness, high-temperature strength, and dimensional stability of the ceramic core through the synergistic effect of yttrium-stabilized zirconia, yttrium oxide powder, alumina-toughened zirconia powder, yttrium aluminum garnet powder, and thorium oxide, making it suitable for the internal cavity forming of high-temperature alloy hollow castings.

The application discloses a semiconductor-dielectric-conductor type attenuation porcelain and a preparation method thereof, and relates to the technical field of electromagnetic wave absorption and attenuation materials. The attenuation porcelain is composed of a semiconductor phase, a dielectric phase, a conductor phase, a sintering aid and a binder; the conductor phase has a core-shell structure of a nickel-cobalt-cerium alloy solid solution inner core, a nitrogen-doped amorphous carbon intermediate layer and a silicon dioxide shell, and cerium atoms are doped in the nickel-cobalt alloy solid solution lattice in the form of lattice distortion. The preparation method comprises the following steps: preparation of a precursor solution, limited silicon dioxide coating, limited in-situ reduction and defect construction, mixing and forming, and high-temperature sintering. Through the synergistic effect of the semiconductor phase, the dielectric phase and the core-shell conductor phase, the application realizes comprehensive enhancement of impedance matching, interface polarization, conductive loss and multiple scattering attenuation, and can improve the high-temperature stability and electromagnetic wave attenuation performance of the attenuation porcelain.

This invention discloses a preparation process for a high-density tungsten-cobalt cemented carbide, relating to the field of cemented carbide preparation technology. The process includes the following steps: S1: Batching: Tungsten carbide powder, cobalt powder, and a forming agent are precisely weighed according to a preset mass percentage and placed in a high-efficiency mixing device for pre-mixing to ensure that the components are initially and uniformly dispersed, resulting in a stable tungsten-cobalt mixture. This invention employs a multi-stage densification process involving wet ball milling, spray drying, die pressing, and cold isostatic pressing. This not only ensures that the mixture particles are sufficiently refined and uniformly dispersed, producing spherical composite powder with excellent flowability and significantly reducing internal defects in the formed blank, but also further enhances the density and uniformity of the blank through cold isostatic pressing, providing a good foundation for subsequent full densification during sintering, effectively reducing the porosity of the finished alloy and improving the overall structural stability.

The application discloses a method for constructing a multi-enzyme complex engineering strain, and has the characteristics that the method comprises the following steps: S1, constructing a light decarboxylase FAP and an oil-producing yeast fatty acid synthase fusion expression vector; S2, electrically shocking and transforming the constructed target vector into an agrobacterium competent AGL1, and introducing the target vector into a starting strain through an agrobacterium-mediated transformation method to obtain an engineering strain that is back-supplemented with a fatty acid defect; the engineering strain that is back-supplemented with the fatty acid defect is obtained, the FAP-FAS2 fusion expression is realized at the same time as the self-assembly of the intracellular FAS1, and a FAP-FAS synthase complex is obtained. The complex not only back-supplements the fatty acid defect function, so that the strain grows normally, but also can synthesize alkanes in the process of blue light irradiation fermentation culture, and realizes the intracellular assembly of protein macromolecules.

This invention discloses a high specific surface area mesoporous tin oxide powder and its preparation method. The method includes: dissolving a tin source in a mixed solvent of alcohol and deionized water, adding a ketone complexing agent and a nonionic dispersant, and stirring to form a tin-based complex precursor solution; then transferring the solution to a hydrothermal reactor for hydrothermal aging treatment, causing the precursor solution to hydrolyze and condense, forming gel particles in situ; after solid-liquid separation, washing with alternating anhydrous ethanol and dilute ammonia water, and drying to obtain the precursor powder; finally, performing staged heating calcination under an air-nitrogen mixed atmosphere, first removing organic components at low temperature, and then completing the crystal phase transformation at high temperature to obtain rutile phase SnO2 powder. The powder has an average particle size of 8–15 nm and a specific surface area of ​​85–110 m² / g. 2 The powder has a pergola size of 3–6 nm and good dispersibility. This invention effectively suppresses grain agglomeration through complexation regulation, hydrothermal-sol-gel coupling, and gradient atmosphere calcination. The prepared powder is suitable for applications such as gas sensors, lithium-ion battery anodes, or transparent conductive films.

This invention belongs to the field of electrical ceramics technology, and relates to a carbon ceramic composite material, its preparation method, and a resistor sheet. The composite material uses clay and kaolin as the ceramic matrix, introduces submicron graphite as the conductive phase, and incorporates nano-ceramic reinforcing powder. It is prepared through multi-stage wet mixing, spray drying granulation, and pressureless sintering under an inert atmosphere. The preparation method involves first pre-treating the material at medium temperature under vacuum to remove moisture and organic matter, followed by high-temperature sintering under inert gas protection to obtain a uniform and dense carbon ceramic composite matrix, on which electrodes and a high-resistivity layer are formed. Through the dispersion strengthening effect of the nano-ceramic reinforcing powder and the synergistic control of process parameters, the microstructure of the material is effectively improved, significantly increasing the compressive and flexural strength of the resistor sheet, reducing the risk of mechanical failure caused by electro-thermal-mechanical shocks during transportation and service, and making it suitable for use in high-voltage and ultra-high-voltage circuit breaker closing resistors.

This invention relates to the field of magnesium alloy smelting technology, and in particular to a smelting process and apparatus for a semi-solid non-dendritic slurry of rare earth AS-based magnesium alloy. Using AS magnesium alloy as the base material and a Ce-La-Nd ternary rare earth mixture as the rare earth modifier, the process involves vacuum melting, electromagnetic stirring, and stepped cooling to obtain an ingot. A three-dimensional curve is plotted based on the JMAK equation to determine the critical temperature. Using a rheological casting apparatus, through internal cooling gradient, stirring-assisted slurry preparation, and ultrasonic-assisted isothermal treatment, combined with three-level quality judgment and defect closed-loop adjustment, a slurry with controllable liquid phase content, fine and rounded grains, and uniform rare earth distribution is prepared. The process exhibits high repeatability and meets the requirements of high-end semi-solid forming.

The application relates to the technical field of alloy materials, in particular to a 4341E high-speed steel and a preparation method thereof. The high-speed steel is characterized in that Ti, B and N elements are introduced for ternary micro-alloying and synergistic modification on the basis of a W-Mo-V-Co component system, nanoscale particles generated in-situ by Ti-N are used as heterogeneous cores to significantly refine grains, the grain boundary is strengthened by the grain boundary segregation effect of boron elements, and the reticular carbide is effectively broken. The obtained steel material realizes perfect matching of high hardness, excellent red hardness and excellent impact toughness, solves the problem that the strength and toughness of traditional high-speed steel are difficult to be compatible, and is particularly suitable for manufacturing high-performance cutting tools, cold and hot precision dies and high-temperature wear-resistant parts.

The invention discloses a high-crystallinity titanate perovskite nanocrystalline powder prepared by adopting an oxalate method and two-stage calcination. The chemical general formula of the powder is Ba1-xMexTiO3 (x is greater than or equal to 0 and less than or equal to 0.2), Me is one or more of Ca, Sr and other elements, the average grain size of the powder is 30-120 nm, the grain size dispersion coefficient s is less than or equal to 0.4, and the powder has a high tetragonal distortion ratio (c / a). The novel oxalate method comprises the following steps: complexing a titanium source and oxalic acid in ethanol, adding a surfactant, reacting with a barium / Me salt solution, and curing to obtain an oxalate precursor; after cleaning and ball-milling refinement, carrying out two-stage calcination: firstly decomposing at 580-800 DEG C and preliminarily forming a phase, and then finishing crystallization optimization at 900-1200 DEG C; the method provided by the invention solves the problems of coarse grains, non-uniform distribution or many defects in the traditional method, and realizes controllable preparation of superfine, uniform and high-crystallinity powder; the powder disclosed by the invention is particularly suitable for manufacturing a miniaturized, high-capacity and high-reliability multilayer ceramic capacitor (MLCC) dielectric layer.

The invention discloses a preparation process of high-Br and high-Hcj sintered neodymium iron boron without heavy rare earth, and belongs to the technical field of rare earth magnetic material preparation. The process comprises the following steps: raw material preparation and precursor preparation: weighing a main phase raw material and an Al-Ga-Cu ternary precursor according to a specific proportion; smelting, vacuumizing, filling argon, preserving heat at 1440-1460 DEG C, and adding a precursor; hydrogen decrepitation dehydrogenation reforming, wherein the temperature is increased to 845-855 DEG C for hydrogen decrepitation, and a parallel magnetic field is applied for dehydrogenation; key sintering is carried out, oxygen partial pressure is controlled to be 4-6 ppm, and the temperature is increased to 847-853 DEG C at a specific rate for sintering; low-temperature self-assembly is conducted, after the temperature is reduced to 600 DEG C, the oxygen partial pressure is increased to 14.5-15.5 ppm, heat preservation is conducted, and then the temperature is reduced to 400 DEG C; and the structure is locked, and the oxygen partial pressure is reduced to 4.5-5.5 ppm and then is cooled to 20-30 DEG C. Through a ternary precursor low-temperature self-assembly mechanism driven by an oxygen potential gradient, collaborative improvement of Br > = 1.45 T and Hcj > = 20 kOe under the condition of no heavy rare earth is realized, the grain boundary phase volume fraction is > = 85%, the problem of collaborative improvement of magnetic performance is solved, and the requirement of a high-end motor for a high-performance permanent magnet can be met.

This invention belongs to the field of piezoelectric materials and discloses a lead nickel tungstate-lead zirconate titanate piezoelectric ceramic and its preparation method. The general chemical formula of the lead nickel tungstate-lead zirconate titanate piezoelectric ceramic of this invention is: xPb(Ni 1 / 2 W 1 / 2 )O3-yPbZrO3-(1-x-y)PbTiO3+zwt%MnO2; where, 0.05

The invention relates to the technical field of ceramic materials, in particular to SiC-TiB2-TiC composite ceramic, a preparation method and application thereof, and the preparation method comprises the following steps: respectively weighing raw material powder according to a component design ratio; uniformly mixing and fully drying; and sintering in a vacuum atmosphere by using a discharge plasma sintering furnace at the sintering temperature of 1900-2000 DEG C under the pressure of 40-60 MPa for 10-15 minutes to finally obtain the compact SiC-TiB2-TiC composite ceramic. In order to solve the problem that commercial TiB2 powder is large in particle size and is directly introduced to cause insufficient electrical properties and electrical discharge machining properties of the SiC-TiB2 composite ceramic, TiC is introduced into a SiC-TiB2 system, and in-situ formation and grain pinning effects in a reaction sintering process are utilized, so that a microstructure is refined, and the connectivity of a conductive network is enhanced. Compared with the composite ceramic without TiC, the material prepared by the invention has more excellent conductivity and electrical discharge machining performance, the preparation process is simple, and complicated subsequent treatment is not needed.

This invention provides a high dielectric constant pulse energy storage ceramic composition and its preparation method, relating to the field of energy storage ceramic materials technology. The ceramic composition uses Ba(Zr) x Ti 1‑x The main component is a perovskite compound (Bi2O3). In addition, it contains Bi as a first secondary component (a composite of Bi2O3 and Bi2O3·nTiO2), and Ca, Sr, Mg, Mn, and Si as secondary components. The ceramic composition of this invention possesses a high dielectric constant (over 900), low dielectric loss, high breakdown field strength, and fine grain structure, making it suitable for high energy density, miniaturized pulse power capacitors.

This invention discloses a cemented carbide and its preparation method. The cemented carbide comprises a hard phase A, a binder phase B, a cubic phase C, and a metallic element M dissolved in the hard phase and the binder phase, respectively. The content of cubic phase C is 0–3 wt.% of the cemented carbide; the content of binder phase B is 3–15 wt.% of the cemented carbide; the solid solution content of metallic element M in the hard phase is 0.1–5 wt.%; the solid solution content of metallic element M in the binder phase is 0.3–15 wt.%; and the balance is the hard phase. The preparation method includes: element homogenization; pre-alloying of the binder phase; reduction-carbonization; strengthening solid solution; secondary carbonization; secondary carbonization; mixture preparation; forming; and sintering. This invention yields a cemented carbide with high strength and toughness, resistance to high-temperature deformation, resistance to high-temperature oxidation, and good corrosion resistance, which can be applied to cutting tools, mining tools, and wear-resistant parts.

The application discloses a preparation method of an impact-resistant non-uniform hard alloy, and the method takes tungsten carbide powder with a particle size of 0.6-0.8 microns and tungsten carbide powder with a particle size of 2-2.5 microns as main raw materials, and is additionally provided with cobalt powder as a binder phase, and is further combined with grain inhibitors such as tantalum carbide, chromium carbide and yttrium oxide to inhibit abnormal growth of fine crystal regions in a sintering process, so as to ensure the stability and high hardness of the fine crystal structure of the bearing substrate, and to form a Zener pinning effect to mechanically hinder the migration of the grain boundary, further refine and stabilize the structure, purify the interface and strengthen the phase combination, and solve the problems of the existing hard alloy, such as difficult consideration of strength and toughness, easy fragmentation under high-speed impact load, sharp performance degradation caused by interface weakening in a high-temperature environment and the like.

A method for preparing a coarse-grained ring-free 6061 aluminum alloy rod belongs to the technical field of aluminum alloy processing and manufacturing. It solves the problem of coarse-grained ring in the production of existing 6061 aluminum alloy rods, which causes uneven mechanical properties, poor fatigue resistance and anodic oxidation appearance defects. The method comprises the following steps: precise alloy component adjustment, low-temperature casting of round ingots, homogenization annealing, temperature-controlled low-speed hot extrusion forming with a round arc working belt mold, high-temperature online quenching, tensile straightening and low-temperature artificial aging. The present application effectively inhibits the abnormal recrystallization and growth of surface grains during the extrusion process, completely eliminates the coarse-grained ring defects of the rod section, and the obtained product has uniform and fine grain structure, stable and excellent mechanical properties, the tensile strength is not less than 310 MPa, the yield strength is not less than 270 MPa, and the elongation after fracture is not less than 12%. The product is suitable for automobile structural parts, rail transit accessories, high-end mechanical equipment and other material scenes, the process is suitable for industrialized batch production, and the production stability is strong and the application range is wide.

The application relates to the technical field of preparation of rare earth alloy sputtering targets, in particular to a terbium-based alloy target and a preparation method thereof. The terbium-based alloy target is prepared by introducing specific amounts of Cu, Al, Ce and Ga elements on the basis of Tb, and through the mutual synergistic effect among the elements, a Tb-Cu-Al-Ga-Ce alloy target with low oxygen content, fine grains, dense and uniform structure and good processing performance is obtained; further, the alloy target can improve the sputtering film forming quality, can improve the heavy rare earth utilization rate and reduce the production cost when used for grain boundary diffusion of a neodymium-iron-boron magnet, can provide a basis for realizing the synergistic promotion of coercivity and remanence, and is suitable for large-scale industrial production in high-end application fields such as new energy vehicles and energy-saving home appliances.

This invention discloses a method for preparing highly spherical zirconia microspheres based on a controllable emulsion template method. Using a water-in-oil emulsion as a template, a composite emulsifier of Span-80 and Tween-80 is employed at a mass ratio of 2:1-4:1, a total concentration of 2-3%, and an oil-to-water volume ratio of 3:1-5:1. Uniform and stable emulsion droplets are formed under a stirring intensity of 800-1500 rpm. The emulsion is then cured at a constant temperature of 50-65℃ for 1-3 hours to allow the gel network to form slowly, preventing microsphere shrinkage and cracking. Finally, a three-stage stepped sintering process is used: increasing the temperature at 1-3℃ / min to 300-400℃ and holding for 1-2 hours; increasing the temperature at 2-5℃ / min to 700-800℃ and holding for 1-2 hours; and increasing the temperature at 3-8℃ / min to 1350-1400℃ and holding for 15-30 minutes to inhibit abnormal grain growth and achieve sufficient densification. Through the coordinated control of emulsification, curing and sintering, the prepared zirconia microspheres have excellent sphericity, particle size uniformity, density and mechanical properties, and the process parameters can be adjusted over a wide range, showing good prospects for industrial application.

This invention relates to the field of electronic ceramic substrates and provides a method for preparing a black alumina substrate, which solves the defects of existing black alumina substrates, such as low thermal conductivity and low mechanical strength, due to defects in the preparation process. The preparation steps include: (1) preparing raw materials; (2) preparing slurry; (3) casting; (4) debinding; (5) sintering; (6) annealing; and (7) surface treatment.

The present application relates to the technical field of alloy, in particular to a high wear-resistant hard alloy mirror polishing plate and a preparation method thereof.The present application realizes directional and nanoscale uniform coating of grain growth inhibitor on the surface of tungsten carbide particles by surface activation of tungsten carbide powder, treatment with vanadium-containing solution and chromium source solution in sequence, formation of layered precursor with internal vanadium and external chromium, and precise segmented cooling process after pre-heat preservation and pressure sintering in liquid phase, so that the hard alloy mirror polishing plate with high hardness, high strength, low surface roughness / waviness and excellent long-term wear resistance is obtained.

This invention provides a variable-temperature forging process for difficult-to-deform lightweight aluminum / magnesium alloys. The process involves determining the recrystallization temperature to lock in the preheating temperature; heating the difficult-to-deform aluminum or magnesium alloy billet to the preheating temperature; maintaining a die temperature 50-200°C higher than the billet temperature; implementing an initial temperature transfer deformation process on a forging press, with the die at a high temperature and the billet at a low temperature; ensuring the die temperature is 50-200°C higher than the billet temperature; performing plastic deformation at the same temperature for both the die and the billet when the forging deformation reaches 1 / 3-2 / 3 of the stage; maintaining pressure with the die temperature 50-100°C lower than the billet temperature; water quenching the formed forging, followed by aging heat treatment. This variable-temperature forging process for difficult-to-deform lightweight aluminum / magnesium alloys reduces the tendency for deformation damage during deformation, ensures low-temperature deformation of the workpiece without damage or cracking, improves the deformation uniformity of the workpiece, and optimizes its microstructure and mechanical properties.

The invention relates to an aluminum nitride ceramic diffusion welding method and an aluminum nitride ceramic heating plate, in particular to the field of aluminum nitride ceramic, and the diffusion welding method comprises the steps that at least two independent aluminum nitride ceramic bodies are subjected to diffusion welding; the heat preservation temperature of diffusion welding ranges from 1000 DEG C to 1750 DEG C, and the pressure ranges from 4 MPa to 25 MPa. According to the diffusion welding method provided by the invention, efficient welding of the aluminum nitride ceramic is realized by optimizing relevant control parameters of diffusion welding, so that an aluminum nitride ceramic product obtained by welding has excellent welding strength and excellent use performance, and meanwhile, a rare earth connecting auxiliary agent is not adopted in the process, so that the cost is remarkably reduced. The diffusion welding process is further optimized, the diffusion welding process of sectional heat preservation and pressure preservation is adopted, the synergistic effect of all the stages is utilized, in the welding process, complete attachment of interface micro-protrusions is achieved, interface air holes are eliminated, abnormal growth of interface phases is avoided, and therefore efficient combination is achieved.