31results about How to "Small sintering shrinkage" patented technology

The invention belongs to the field of porcelain materials and preparation thereof, and in particular relates to a multilayer semitransparent zirconia full-porcelain dental repair material and a preparation method thereof. The material comprises the chemical ingredients such as magnesium oxide and part stable square-phase zirconia, wherein the molecular contents of the magnesium oxide and the zirconia are respectively 2-10% and 90-98%; the part stable square-phase zirconia is added with a modifying agent to be modified, wherein the molar ratio of the modifying agent and the part stable square-phase zirconia is 1: (0.01-0.1); and a coloring agent is added into the modified zirconia repair material, and the coloring agent and the modified zirconia repair material respectively account for 0.1-1% and 99-99.9%. The method comprises the following steps of power preparing, mixing and granulating, two-step forming, plastic discharging and sintering. Compared with the prior art, the material has the advantages of good producing technology repeatability, stable quality, reliable performance and convenience in production.

The invention provides a low-temperature preparation method of high-strength mullite ceramic. Kaolin, aluminum sol and aluminum oxide are taken as raw materials, under the action of a mineralizing agent and sintering aids, mullite porous ceramic with needle-shaped crystal whiskers is firstly synthesized under low temperature, space is provided for the growth of the crystal whiskers by using internal pores of the materials to allow the crystal whiskers grow fully, mullite precursors with higher reaction activities are soaked, and finally the high-strength mullite ceramic is obtained through secondary low-temperature sintering. The method has the advantages that the prices of the raw materials are cheap, sources of the raw materials are extensive and easy to obtain, the costs are lower, andthe preparation temperature is lower, so that production consumption is greatly reduced, the process is simple, equipment demands are low, the improvement of material strength and toughness are achieved simultaneously by the in-situ growing crystal whiskers, during the sintering process, the shrinkage of products is less, and net size shaping can be achieved.

The invention provides a preparation method of a large-size zirconia-based heat insulation material, and the heat insulation prepared by adopting the method. The preparation method comprises the following steps: 1, mixing deionized water, organic monomers and a cross-linking agent, adding alpha-Al2O3 powder, ZrO2 powder and a dispersant, and carrying out ball milling by adopting a zirconium dioxide ball to obtain a slurry; 2, adding an initiator and a catalyst to the slurry obtained in step 1, stirring, injecting the obtained mixture to a die, solidifying, and cooling to obtain a wet green body; and 3, drying the wet green body obtained in step 2, and sintering. The preparation method comprises special blank molding treatment according to the formula of specific powder, so the problem of adverseness of too large shrinkage in the zirconia sintering process to pore maintenance is effectively solved, the deformation and cracking problems appearing in the drying process of gel injection molded large-size green body are avoided, and the obtained green body has the advantages of high uniformity and small drying shrinkage.

The invention relates to a preparation method for high-crystallinity silver powder. The preparation method is characterized by comprising the following steps of: firstly, synthesizing a silver carbonate precursor; uniformly coating the silver carbonate precursor by using a coating agent; and performing low-temperature crystal water removing, high-temperature thermal decomposition, densification sintering and washing on the coated silver carbonate precursor to obtain high-crystallinity silver powder. Due to the adoption of the method disclosed by the invention, high-crystallinity silver powder of which the particle diameter is 0.1-5 mu m and the tap density is 3.0-7.0 g/cm<3> can be finally obtained; the silver powder can be used for preparing silver slurry or silver paste for fine threads and high-accuracy printed galvanic circles; the silver powder has the advantages of high dispersity, high crystallinity, superior degree of sphericity, uniform particle size distribution, easiness for dispersing in silver slurry or silver paste and high filling characteristic, so that high-accuracy fine thread printing can be realized; and meanwhile, an obtained silver thick film has low sintering concentration rate and low bulk resistivity.

The invention discloses a preparation method and application of a silicon-based ceramic core. Mixed slurry obtained according to the mixing ratio is formed by using a photocuring method to obtain a mold core biscuit, the mold core biscuit is degreased and then impregnated with a ceramic slurry, the impregnated mold core biscuit is dried, and the dried mold core biscuit is sintered in an air atmosphere by using a buried powder sintering method to obtain the silicon-based ceramic core. By means of the method, forming of a high-surface-precision silicon-based ceramic core blank can be achieved, the forming precision of the silicon-based ceramic core is improved, the production process of the ceramic core is accelerated, and the forming difficulty of the silicon-based ceramic core of a complexstructure is lowered. Degreasing and sintering treatment are carried out on the mold core biscuit obtained through the photocuring method, dipping lifting treatment is carried out on the mold core biscuit through the silicon oxide inorganic slurry, and the surface precision of the silicon-based ceramic mold core blank can be effectively improved. The method is simple, and the forming difficulty of the silicon-based ceramic mold core with a complex structure is reduced.

The invention provides a preparation method of a high-performance sintered insulation brick. The method comprises the following steps: step one, concentrating, pressing-filtering and drying sludge ofurban sewage treatment plant or sludge of the paper mill; step two, naturally airing, crushing, grinding and sieving the clay and sludge; step three, uniformly mixing various raw materials to obtain amixture drier, adding water to stir uniformly; step four, performing ageing treatment on the wet mixture, wherein the ageing time needs to exceed 24 hours; step five, performing compression molding on the brickmaking blank to obtain the green brick; step six, naturally drying the green brick under room temperature, and then feeding into a tunnel drying kiln to dry; step seven; directly feeding the green brick into a tunnel sintering kiln after the drying, wherein the sintering temperature is 950-1100 DEG C, wherein the heat preservation time of the brick body at the highest sintering temperature is 1-3 hours. The defects that the traditional insulation brick is poor in mechanical performance and high in heat conductivity are overcome; the production of the high-performance insulation brick with large sludge dosage is realized; the raw material sources are wide; the cost is low; various production and domestic sludge are greatly consumed.

The invention relates to a polycrystalline zirconia ceramic tooth post material and a preparation method thereof, belonging to the technical field of preparation of ceramic materials. It is characterized in that: the material contains zirconia ceramic powder as the initial raw material, a polymer binder, and a low-molecular additive, and the proportion thereof is: 80-90wt% of zirconia ceramic powder, 5-10wt% of polymer binder, 5-10wt% of low-molecular additives. The preparation method includes four steps of mixing and granulation, injection molding, thermal degreasing and sintering. The thermal degreasing temperature is 500-800°C, and the sintering temperature is 1350-1550°C. The organic binder system for injection molding of the present invention has good fluidity and high density of the molded green body, and the density of the ceramic product after sintering is greater than 6.0 g/cm ³ ;The sintering shrinkage and deformation of the formed green body are small, which ensures the dimensional accuracy of the product; the bending strength of the prepared ceramic tooth post is greater than 600MPa, and the fracture toughness is as high as 13MPa.m ^1/2 , elastic modulus 140MPa, Vickers hardness 1050 ~ 1200MPa. The preparation process has good repeatability and is convenient for industrialized production.

The invention relates to a silicon oxide-based ceramic core for a large-size directional hollow blade of a heavy gas turbine and a preparation method of the silicon oxide-based ceramic core. The silicon oxide-based ceramic core adopts quartz glass powder as a base material, and adopts zircon powder, alumina powder and calcium oxide powder as mineralizing agents. The powder comprises the following components in percentage by weight: 60-95% of quartz glass powder, 1-30% of zircon powder, 0.5-5% of alumina powder and 0.1-5% of calcium carbonate powder. Paraffin, beeswax, polyethylene and polyethylene glycol are used as plasticizers for hot-press injection molding. The preparation method comprises the following steps: ball-milling and uniformly mixing the powder materials, putting the powder materials into a molten plasticizer for mixing, and carrying out hot-press injection molding on a ceramic core molding machine. A quartz glass rod/tube is pre-arranged in the position, corresponding to the thick and large section of the mold core, in the mold core mold before pressure injection, and the ceramic mold core formed through hot pressure injection molding is put into a box-type resistance furnace to be roasted after being trimmed and corrected. The silicon oxide-based ceramic core prepared by the invention has the characteristics of high high-temperature strength, good creep resistance, small firing shrinkage, stable size and high core removal efficiency.

The invention discloses an aluminum-silicon castable prepared by adjusting the aggregate ratio and a preparation method thereof, and the aluminum-silicon castable comprises the following raw materials in percentage by mass: 35-40% of calcium aluminate cement, 1-4% of floating beads, 10-15% of sinking beads, 3-6% of silicon micro powder, 20%-32% of perlite aggregate, and 15%-25% of ceramsite aggregate. According to the aluminum-silicon castable by adjusting the aggregate proportion and the preparation method of the aluminum-silicon castable, the perlite is used as the aggregate, so that the aluminum-silicon castable is light, porous, environment-friendly, pollution-free, capable of absorbing sound and noise, heat-insulating, non-combustible, good in free-running property, excellent in compressive strength and the like, the fluidity of the castable can be remarkably improved by adding the electric smelting ceramsite sand, the strength is improved, and the sintering shrinkage is reduced; and the composite aggregate perlite and the capacitor ceramsite sand are added, so that performance advantages are complementary, and the performance of the aluminum-silicon castable is improved.

The invention discloses a production method of high-strength and high-compactness fused quartz. The production method comprises the following steps: (1) producing a fused quartz raw material; (2) preparing slurry, namely performing ball milling on the fused quartz raw material and cordierite by adopting a ball mill at the rotating speed of 250-300r/min in a forward and reverse ball milling mannerfor 6-10h, sieving the powder by using a 500-mesh sieve, adding the powder subjected to ball milling into a precursor solution, adding a dispersing agent, adjusting the pH value to 3-4 through lacticacid and ammonia water, and preparing slurry with the solid phase content of 60-65% through mechanical stirring; (3) conducting gel curing; (4) conducting drying; and (5) conducting microwave sintering. According to the production method of the high-strength and high-compactness fused quartz, the production method is simple and efficient, the influence of impurity elements on the chemical stability, strength and compactness of the high-strength and high-compactness fused quartz is avoided, and the prepared fused quartz has good breaking strength, high compactness, good chemical stability and wide application prospects.

The invention provides a refractory brick. The refractory brick is prepared from alumina, mullite, silica powder, silicon metal, silicon iron, Al2O3 and sodium phosphate. Compared with the prior art, alumina, mullite, Al2O3 and other main raw materials in the refractory brick have good refractory properties, weakly react with sodium salt at the use temperature and are not prone to excessive sintering or over-sintering; the refractory brick contains silicon metal and silicon iron, so that oxidation appears at the use temperature, and certain volume expansion can be generated, and contraction caused by sintering can be partly counteracted. Under the combined action of the various raw materials, the refractory brick has little sintering contraction when slag of vanadium and chromium is calcined for sodium modification. The invention further provides a preparation method of the refractory brick.

The invention relates to a zirconia ceramic preparation method, which comprises: sequentially carrying out forward drip co-precipitation and reverse drip co-precipitation by controlling the concentrations of a ZrOCl2.8H2O solution and ammonia water, washing the precipitate, drying, calcining to obtain primary zirconia powder with wide particle size distribution, carrying out ball milling, granulating, molding, sintering, and annealing to obtain the zirconia ceramic. With the preparation method of the present invention, the sintering shrinkage rate of the zirconia ceramic can be effectively reduced while the high fracture toughness can be maintained. The present invention further relates to the zirconia ceramic prepared according to the preparation method.

A high-density super-hard material manufacturing method includes the steps: weighing formula raw materials; uniformly stirring the formula raw materials in a mixer; pre-forming the formula raw materials by a hydraulic former; performing vacuum pumping seal in a flexible film bag; performing isostatic pressing secondary pressure shaping in a high-pressure container; demolding; performing normal pressure sintering in an electric furnace; forming products. The manufacturing method has the advantages that product blanks are more compact and higher in strength and damage to semi-finished products is low in the production process as the product blanks in the high-pressure container are secondarily pressurized and shaped in different directions by the aid of pressurizing media, the product blanks are uniform in density, low in sintering shrinkage and high in dimensional precision, so that high compactness and high strength of the products are ensured, the yield of the products is improved, hot pressed sintering of the product blanks in the intermittent electric furnace is omitted, so that the product blanks can be sintered in a continuous electric kiln, the labor intensity of workers is greatly relieved, production efficiency is improved, and production cost is reduced.