646results about How to "High sintering activity" patented technology

A process for producing a composite, containing at least one shrinkage-matched ceramic layer, wherein a starting material for the ceramic layer(s) has shrinkage behavior on sintering which is matched to remaining layer(s), and which is selected such that the ceramic-forming constituent of the same contains at least one ceramic powder of a specific size, and which process entails joining the layers of the composite by sintering.

The invention relates to yttria-stabilized zirconia powder and a preparation method thereof. The yttria-stabilized zirconia powder has the composition characteristics that yttria is taken as a stabilizer of a zirconia material; the powder comprises a doping system formed by one or more following third components: alumina, ceria, lanthana, copper oxide, magnesium oxide and calcium oxide, wherein the weight of the yttria is 2-8mol%, and the total doping weight of the alumina, the ceria, the lanthana, the copper oxide, the magnesium oxide and the calcium oxide is 0-5wt%. According to the yttria-stabilized zirconia powder and the preparation method, the deficiencies of an existing liquid phase preparation process of nanometer zirconia powder are overcome, and the prepared nanometer ZrO2 composite powder has the performance of uniformity in dispersion of components, uniform grain size, super-fineness, high sintering activity, good liquidity and the like. Furthermore, the preparation method is simple in process and low in cost and is easy to industrialize.

The invention provides a method for preparing sulfur and nitrogen co-doped titanium dioxide with visible light catalytic activity, which adopts a sol-gel method and comprises the following steps: hydrolyzing titanium ester and introducing sulfur and nitrogen sources to obtain a titanium dioxide sol, wherein the sulfur and nitrogen sources are from thiourea solution; in a sol system, dropwise adding 1 to 5 percent saturated aqueous solution of thiourea to perform the hydrolysis reaction to obtain the sol; then performing aging and volatilizing a diluent to obtain a titanium dioxide gel; drying the titanium dioxide gel and grinding into powders; performing heat treatment on the solid powder; and calcinating to obtain sulfur and nitrogen co-doped titanium dioxide nano powder. In the method, the thiourea is used as the raw materials of the nitrogen and sulfur sources, the sulfur and the nitrogen are simultaneously introduced in the process of the hydrolysis reaction of the sol to achieve synergistic effect and improve the reaction efficiency, raw material consumption is less, the process is simplified, the absorption range of visible light is effectively improved, the wavelength of the visible light is expanded to about 650nm, and the sulfur and nitrogen co-doped titanium dioxide has obvious visible light activity in the photocatalytic degradation reaction of organic pollutant molecules.

The invention discloses a preparation method of copper-coated tungsten composite powder, belonging to the technical field of powder metallurgy. Corresponding tungsten powder and blue vitriod are employed according to the weight ratio of composite powder to be prepared and the tungsten powder is pre-treated; copper sulphate and seignette sol are dissolved into solution; bipyridine is added and NaOH is used to adjust pH value to 12-14; an appropriate amount of formaldehyde solution and the tungsten powder are added; the mixture is heated and then stirred continuously in constant-temperature bathing at 30-60 DEG C until the tungsten powder is red; the tungsten powder is washed, dried, reduced and annealed, thereby obtaining copper-coated tungsten composite powder. The preparation method of copper-coated tungsten composite powder has wide application range and is applicable to tungsten-powder coating coppers with different finenesses and shapes. The preparation method of copper-coated tungsten composite powder prepares copper-coated tungsten composite powder in different content ratios according to different requirements. The copper-coated tungsten composite powder obtained by the method of the invention has excellent sintering activity, thereby improving the combination property of tungsten copper alloy.

This invention relates to PEN multilayer film of warm solid oxide full cell and its processing method characterized by multiple doctor-blading layer by layer or stratified doctor-blading and multi-layer co-rolling, then lour-temp. co-senlering to obtain anode/electrolyte double-layer film, after that, preparation of cathode layer and PEN multilayer, film, in which the thickness of NiO+DCO porous anode layer is 0.5-1 mm, NiO content or crysal size expressing graded distribution along the thickness direction. Weight content varies from 70-80% to 50-60%, crystal size varies from 5-8 um to 1-3 um, DCO electrolyte thickness is 20-150 um, with relative density higher than 96%, and thickness of LaCoO3 porous cathode layer of 30-50 um.

The invention relates to a high-temperature-resistant high-strength aluminum oxide fiber enhanced composite material and a preparation method thereof. The preparation method comprises the following steps of: by taking a two-dimensional cloth paving layer and 2.5D woven or orthogonally three-dimensional woven continuous aluminum oxide fiber preform as an enhancer, preparing a matrix through a double nano composite impregnation liquid where silicon dioxide and aluminum oxide are uniformly mixed; and finally obtaining the aluminum oxide fiber enhanced composite material through the process of vacuum pressure impregnation, micro-positive pressure medium and low temperature pre-curing, micro-positive pressure curing and atmosphere temperature programming sub-sectional thermal treatment, wherein the mass ratio of silicon dioxide to aluminum oxide in the composite material is (19:1)-(12:8), and the volume content of the aluminum oxide fibers is 30-60%. The prepared composite material has a high-temperature-resistant property and a high-temperature mechanical property, and is high in compactness; the room temperature tensile strength of the material reaches 310+/-30MPa, the tensile strength at 1100 DEG C reaches 135+/-20MPa, and the tensile strength at 1200 DEG C reaches 90+/-10MPa; and compared with a similar quartz fiber enhanced silicon dioxide oxide/oxide composite material, the performance is improved by 4-5 times.

The invention discloses a sintering preparation method of boron carbide ceramic, which comprises the following steps: 1. sintering: carrying out mixing and ball milling on boron carbide powder, carbon powder, metal powder, a dispersant, an adhesive and deionized water to make a slurry, carrying out spray granulation, pressing into a biscuit, presintering for debonding, and carrying out thermal-insulation sintering at lower sintering temperature (slightly higher than the melting point of metal), thereby implementing primary shrinkage sintering of the product by utilizing the surface tension of the molten metal in the system; and 2. sintering: continuing enhancing the sintering temperature, carrying out in-situ reaction to generate metal carbide, metal boride or metal boro-carbide and nano B4C which have higher sintering activity, and forming a solid solution with boron carbide granules by using the metal carbide, metal boride or metal boro-carbide and nano B4C as sintering assistants to promote the further shrinkage sintering of the system, thereby obtaining the high-performance boron carbide ceramic. The method has the advantages of both the normal-pressure sintering technique and the reactive sintering technique.

The invention discloses a preparation method for a super coarse crystal WC-Co hard alloy. According to the preparation method, a proper amount of fine tungsten carbide powder is added into a raw material, and the super coarse crystal WC-Co hard alloy is prepared by proper ball milling and sintering processes, so that the super coarse crystal hard alloy with the grain size of 6.0 to 14.0 microns can be prepared successfully. The preparation method has the characteristics that the process is simple, the process is easy to control, the production cost is low, and the WC grain size distribution in the alloy product is uniform.

The invention relates to a preparation method of uranium nitride fuel powder and a pellet, which comprises the following steps: (1) carrying out surface cleaning treatment on a pure metal uranium lump; (2) hydrogenating the pure metal uranium lump in hydrogen at 150-300 DEG C for 2-16 hours, dehydrogenating in a vacuum, and repeating the hydrogenation-dehydrogenation several times to obtain metal uranium powder; (3) nitridizing the metal uranium powder in nitrogen at 200-600 DEG C for 6-24 hours to obtain U2N3 powder; (4) denitrifying the U2N3 powder in a mold, keeping the system vacuum, pressurizing the mold to 30-60 MPa, sintering at 1450-1620 DEG C for 1-2 hours, and cooling to obtain the UN ceramic pellet. The method provided by the invention is simple in technique and easy to control; and the obtained intermediate product U2N3 powder has higher purity and higher sintering activity, and can be finally subjected to hot pressed sintering to obtain the UN fuel pellet of which the TD is up to 98.9%.

The invention relates to a method of preparing a Mo-Cu composite material. A mixture ball consisting of 85 to 95 weight percent Mo powder, 4.65 to 14.5weight percent Cu powder and 0.35 to 0.5weight percent Ni powder is milled into mechanical alloying composite powder; after pressing and shaping, the Mo-Cu composite material is made after the power is sintered in a hydrogen sinter furnace. The Mo-Cu composite material of the invention has relative density of up to 98percent, which not only meets the use requirements of materials of parts of high-performance engines and other heat sink materials, but also is characterized by oxidation resistance, corrosion resistance, creep resistance, fatigue resistance and tiny deformation at high temperature.

The invention discloses a preparation method of yttrium aluminium garnet doped transparent laser ceramics. The method includes using an alcohol-aqueous system stepping chemical co-precipitation method to firstly prepare high-dispersity and high-activity nanometer Y2O3 oxide powders, Al2O3 oxide powders and rare earth (Re) oxide powders, weighing raw materials of the powders according to a stoichiometric ratio of Y<3-x>RexAl5O12 when the powders are prepared, placing the powders, sintering aids, dispersing agents and absolute ethyl alcohol into a ball-milling tank for ball milling, drying ball-milling mixing slurries into powders, forming the powders into green bodies with certain shapes by dry pressing, and then subjecting the green bodies to isostatic cool pressing to obtain ceramic biscuits. The ceramic biscuits are subjected to binder removing, vacuum sintering, powder-burying hot-pressing post-processing, annealing and optical polishing to obtain Re:YAG transparent ceramics. The preparation method has the advantages of being controllable, high in repeatability, low in cost and high in transmittance.

The invention discloses a NiZnCu ferrite material, which is a ferrite material made by adding organic additives and inorganic oxide additives in the base raw material prescription of Fe[2] O [3], NiO, or Ni [2] O [3], CuO, ZnO. The reparing method includes: adding the raw material and the organic additives into the inorganic oxide additives, mixing with water, drying, sifting; presintering; joining the organic additives again, adding water for ball milling, mixing; drying and then sifting, to obtain the inventive NiZnCu ferrite material. Granulation, molding and sintering is required during manufacturing magnet ring. Compared with the existing technology, this invention adds organic additives twice to make the prescription and process simpler, reduce the cost and presintering temperature, improve the sintering activity of the presintering material so that the sintering temperature scope becomes wider, and obtain a NiZnCu ferrite material with a good consistency of production batches, suitability for industrial production, high magnetic permeability and Q value stability.

The invention discloses a method for preparing tungsten carbide nano-powder. The method comprises the following steps of: dissolving ammonium paratungstate and citric acid in deionized water, and performing complexation in water bath; filtering and drying to obtain a precursor of tungsten oxide, and calcining under air atmosphere to obtain tungsten oxide powder; putting the obtained tungsten oxide powder in a tube furnace, introducing ammonia and nitriding to obtain tungsten nitride powder; mixing the obtained tungsten nitride powder and carbon black, performing ball milling, performing rotary evaporation drying and performing heat treatment under the air pressure of less than 200 Pa or inert atmosphere; or putting the obtained tungsten nitride powder in the tube furnace, and introducing the mixed gas of methane and hydrogen and carbonizing to obtain the tungsten carbide nano-powder. The preparation process of the method is simple, practical, and high in controllability and can easily realize large-scale production; the particle size of the prepared powder is small, the particle size distribution is uniform and the aggregation degree is low; and the method has high sintering activity, and densification can be realized by performing hot pressing sintering at the temperature of 1,700 DEG C.

The invention discloses a preparation method of transparent yttria ceramic, in particular relates to an ammonium bicarbonate co-precipitation method of Nd:Y2O3 nano powder. The method comprises the following steps: slowly dropwise adding a precipitator ammonium bicarbonate solution in a mixed solution prepared from yttrium, doped rare earth ion, (NH4)2SO4, polyacrylic acid (PAA) and MgSO4.7H2O at room temperature by using a positive-titration method so as to prepare a precursor, washing and drying; then calcining; carrying out preliminary press molding, cold isostatic pressing, vacuum sintering, annealing and polishing to obtain the transparent yttria ceramic. In the method, self-made high-activity nano powder is used for preparing the transparent yttria ceramic at low temperature; and the process is simple and practicable, and the prepared transparent yttria ceramic has a good optical property.

The invention discloses a preparation method of rare-earth tantalate high-temperature ceramic. Adding RE2O3 into concentrated nitric acid, reacting to obtain a mixture, then adding TaOCl3 for mixing and stirring for 0.5 hour, adding mass of strong ammonia water to control the pH value of the reaction system to be 9 to 11, stirring to obtain a precipitated colloid, and performing filtration ,washing, drying, roasting, tabletting and sintering on the precipitated colloid to obtain the rare-earth tantalate high-temperature ceramic. According to the preparation method provided by the invention, the process purity is high, the impurity content is low, the sample is compact, the product preparation cost is low, the preparation method is suitable for production in batch, and the target product is likely to be used as a novel ceramic material with high temperature-resistance, oxidation resistance and wear-resistance.

The invention relates to a pressureless sintering preparation method for boron carbide ceramic, and coarse particle powder with the particle size larger than 2 micrometers is taken as raw materials. The method comprises the following steps that 70-80 wt % of boron carbide powder (D50>=2 micrometers), 4-8 wt% of carbon powder and 0.7-2 wt% of yttrium oxide powder are put into a ball mill mixing container, ball mill slurrying is performed after binding agents, dispersing agents and deionized water are added, and the solid phase content of obtained slurry is 25-45 wt%; the obtained slurry is prepared into granulating powder with a spray drying granulating machine; the granulating powder is pressed into green bodies by adopting a dry-pressing molding technology or isostatic cool pressing molding technology at 100-200 MPa; the green bodies are placed in a vacuum furnace, a vacuum or normal pressure sintering mode is adopted, heat preservation is performed for 0.5-5 h at the temperature of 2000 DEG C-2300 DEG C, sintering is completed, and then the boron carbide ceramic is obtained. According to the pressureless sintering preparation method for the boron carbide ceramic, due to the fact that the coarse particle boron carbide powder which is low in cost is adopted as the raw materials and the pressureless sintering technology capable of achieving scale production is adopted, the preparation cost of the boron carbide ceramic can be greatly lowered, and therefore the method is suitable for the fields of nuclear power, semiconductor equipment, armor protection and the like.

The invention relates to a preparation method of a polycrystalline cubic boron nitride (PcBN) composite material, which comprises the following steps: by using nonstoichiometric titanium nitride (TiNX, 0.3<=x<=0.6) as the basic component of a binder in the PcBN composite material, constituting a binder with one or both of aluminum nitride (AlN) and titanium carbide (TiC), and sintering with monocrystalline cubic boron nitride (cBN) under the conditions of high temperature and high pressure to prepare the PcBN composite material, wherein the pressure is 4-6.5GPa, the temperature is 1400-1650 DEG C, and such pressure and temperature are kept for 1-25 minutes. Since the PcBN composite material is prepared from the cBN and the binder mainly composed of the nonstoichiometric titanium nitride (TiNX, 0.3<=x<=0.6), the polycrystal does not contain any simple substance element or alloy phase, thereby avoiding the existence of soft spot. The hardness of the obtained PcBN composite material is up to 38-55GPa, and the fracture toughness is up to 3.31-4.12MPa.m1/2.

The invention provides a preparation method for promoting to sinter zirconium boride or zirconium carbide ceramics by using reaction aids. Two-phase sintering aids capable of being reacted, namely Zr powder and C powder, or Zr powder and B4C powder, are added, and a material is promoted to be compact and crystals of a matrix are inhibited from growing by zirconium carbide/zirconium boride second phase particles with higher sintering activity, which are generated through in-situ reaction between the sintering aids. The ZrB2 or ZrC-based bulk material prepared by the method has the relative density of over 97 percent, the room temperature bending strength of 500-800MPa, the fracture toughness of 3.5-6.5MPa.ml/2, and the hardness of 14-20GPa. The second phase generated through the in-situ reaction has the same melting point as the matrix, and the sintering acids cannot bring adverse effect to the high temperature mechanical properties of the material.