747 results about "Alumina ceramic" patented technology

The invention discloses a preparation process of an aluminum oxide ceramic material, which comprises the following steps: S1, pretreatment of aluminum oxide powder: taking alpha-Al2O3 powder as a raw material, adding a dispersion medium, carrying out ball milling, transferring into an ultrasonic dispersion machine, dispersing, and further carrying out vacuum drying to obtain pretreated aluminum oxide powder; s2, chemical activation treatment: weighing pretreated aluminum oxide, magnesium oxide, nano silicon dioxide, calcium oxide, zirconium dioxide, titanium dioxide and modified nano silicon carbide in parts by weight, mixing, sequentially adding a dispersing agent absolute ethyl alcohol and a KH550 silane coupling agent, stirring at a high speed, adding a polyvinyl alcohol binder, and continuously stirring to obtain ceramic slurry; s3, sieving the ceramic slurry, filling the ceramic slurry into a mold, and performing isostatic pressing to obtain a ceramic green body; and S4, putting the ceramic green body into a box-type sintering furnace, sintering step by step, and cooling to room temperature along with the furnace to obtain the aluminum oxide ceramic material. The prepared aluminum oxide ceramic material has high compactness, excellent dielectric strength and mechanical property, low energy consumption and great application potential.

The invention discloses reflection-heat insulation dual-functional aluminum oxide ceramic and a preparation method and application thereof.The method comprises the steps that after surface silanization treatment is conducted on nanoscale hollow oxide filler, surface-modified nanoscale hollow oxide filler is prepared; and then adding the surface-modified nanoscale hollow oxide filler into a high-molecular polymer and a mixed polar solvent to obtain the thermal insulation coating. The method comprises the following steps: coating the surface of aluminum oxide ceramic with a heat insulation coating to form a primary coating, and carrying out gradient heating curing to obtain aluminum oxide ceramic with a functionalized heat insulation coating; and coating the surface of the thermal insulation coating functionalized aluminum oxide ceramic with an infrared reflection coating, and carrying out annealing treatment in a nitrogen atmosphere to prepare the reflection-thermal insulation dual-functionalized aluminum oxide ceramic. By constructing a double-layer composite structure, enhancing interface thermal resistance through chemical bonding, directionally distributing the nanofiller and designing a low-radiation layer structure, heat conduction and radiation heat transfer of the aluminum oxide ceramic-based material are synergistically reduced, and the high-temperature heat insulation performance of the aluminum oxide ceramic-based material is improved.

The invention relates to the technical field of ceramics, and discloses an aluminum oxide ceramic glaze based on domestic waste ceramics, and a preparation method and application thereof. The aluminum oxide ceramic glaze comprises the following raw materials in parts by weight: 28-42 parts of domestic waste ceramic, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of aluminum oxide, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide and 3-6 parts of self-repairing particles. The self-repairing particles comprise mesoporous alumina doped with Si and Zr, and V2O5-B2O3-TeO2 series glass which is filled in pores of the mesoporous alumina and has a softening point of 200-300 DEG C. After the glaze is applied to the surface of the aluminum oxide ceramic to form a glaze layer, the insulativity of the aluminum oxide ceramic can be effectively improved, meanwhile, the high bonding stability between the glaze layer and the aluminum oxide ceramic can be achieved, and the problems that the insulativity is greatly reduced and the glaze layer cracks during heat circulation are solved.

The invention relates to the technical field of ceramic substrates, and provides a bending-resistant aluminum oxide multilayer ceramic substrate and a preparation method thereof. The bending-resistant aluminum oxide multilayer ceramic substrate comprises the following raw material components in parts by weight: 95-110 parts of aluminum oxide, 3-8 parts of a plasticizer, 6-12 parts of an auxiliary agent, 4-7 parts of a binder, 3-6 parts of a dispersant and 60-70 parts of a solvent, the preparation method of the additive comprises the following steps: A1, adding calcium oxide into ethanol, adding glucose, stirring until the materials are uniformly mixed, and concentrating to obtain a glucose coated material; a2, carrying out annealing treatment on the glucose coated material to obtain a carbon coated material; and A3, uniformly mixing the carbon-coated material with magnesium oxide and titanium dioxide, and carrying out ball milling to obtain the auxiliary agent. According to the technical scheme, the problem of low mechanical property of the aluminum oxide ceramic substrate in the prior art is solved.

The invention relates to the technical field of ceramic substrates, and provides a high-toughness aluminum oxide ceramic substrate and a preparation method thereof, the high-toughness aluminum oxide ceramic substrate comprises the following raw materials by weight: 100 parts of aluminum oxide, 1-3 parts of a plasticizer, 4-6 parts of an auxiliary agent, 4-6 parts of a binder, 1-3 parts of a dispersant, and 55-65 parts of water; the auxiliary agent is composed of an auxiliary agent A and an auxiliary agent B, the auxiliary agent A comprises rare earth oxide, and the auxiliary agent B is composed of molybdenum boride, scandium oxide and zirconium oxide. According to the technical scheme, the problem of low toughness of the aluminum oxide ceramic substrate in the prior art is solved.

The invention belongs to the field of conductive aluminum oxide ceramic preparation, and particularly relates to a treatment method for performing carbon deposition infiltration on the surface of aluminum oxide ceramic to enable the aluminum oxide ceramic to have certain conductivity. According to the invention, wheat starch and corn starch are used as main raw materials and are converted into a volatile carbon source through a high-temperature carbonization process under the protection of inert gas; and placing the carbon source and aluminum oxide ceramic pre-subjected to conductive treatment in a high-temperature furnace protected by inert gas, and performing deposition carburizing treatment on the surface of the aluminum oxide ceramic at 800-900 DEG C to obtain the aluminum oxide conductive ceramic with certain conductivity. The method is low in raw material cost, low in sintering temperature of the related process, low in equipment investment, good in surface carburization uniformity of the aluminum oxide ceramic and stable in property.

The invention provides a preparation method of a high-thermal-conductivity 99 aluminum oxide ceramic substrate, and belongs to the field of electronic ceramic materials. The method comprises the following steps: homogenizing and grinding a high-purity aluminum-containing compound and a modifier to obtain pretreated powder; mixing the pretreated powder with a carrier gas, and carrying out melt spheroidization to obtain a submicron spherical alumina precursor raw material; homogenizing and defoaming the submicron spherical aluminum oxide precursor raw material, an inorganic sintering aid, a dispersing agent, a binder, a plasticizer and a foam inhibitor in a solvent to obtain ceramic slurry; carrying out tape casting on the ceramic slurry to obtain an aluminum oxide green body; the alumina green body is subjected to rubber discharging, pre-sintering and sintering, and the 99 alumina ceramic substrate is obtained. The submicron spherical alumina powder is prepared through a melt spheroidizing process, the surface of the powder is smooth, particle size distribution is concentrated, grain boundary resistance between the powder is remarkably reduced, sintering densification is promoted, and therefore the technical problems that existing tape casting slurry is poor in stability and high in sintering temperature, and consequently microdefects are caused are solved.

The invention discloses a seawater conductivity sensor electrode material based on a copper-nickel-based nanostructure and a preparation method, the electrode material comprises: a substrate, a copper-nickel-based nanostructure layer being formed on the surface of the substrate; the substrate comprises an insulating compound and a coating coated on the surface of the insulating compound, the insulating compound comprises at least one of high-resistance silicon, silicon oxide, aluminum oxide ceramic and plastic, the coating comprises a metal coating and / or a semiconductor coating, and the copper-nickel-based nanostructure layer is in a dendritic crystal or cluster form. The copper-nickel alloy nanostructure is a core material of the electrode, so that the electrode material has high specific surface area and rich active sites, the measurement accuracy and measurement limit of the electrode material can be improved, the service life can be prolonged, the manufacturing cost can be reduced, and the application requirements of the ocean Internet of Things can be met.

The invention provides modified zirconium silicate whisker reinforced aluminum oxide ceramic as well as a preparation method and application thereof, and belongs to the technical field of new materials. The preparation method comprises the following steps: modifying the surface of alumina powder with a silane coupling agent with sulfydryl to generate zirconium silicate in situ, uniformly mixing the zirconium silicate with zirconium silicate whiskers which are treated by hydrogen peroxide and modified by phytic acid and tannic acid and a CeO2-Y2O3-MgO-SiO2 compound, and performing spark plasma sintering to obtain the modified zirconium silicate whisker reinforced alumina ceramic. The modified zirconium silicate whisker reinforced aluminum oxide ceramic prepared by the invention has better interface bonding force, excellent mechanical properties and good wear resistance, realizes ceramic densification, and has wide application prospects.

The invention relates to a mold for forming a large-size three-hole ceramic guide rail and a forming process, and belongs to the technical field of ceramic forming. The die comprises an auxiliary die sleeve, a rubber sleeve, a rubber plug, a positioning disc and a mandrel. The rubber plugs are located at the upper end and the lower end of the rubber sleeve, and the positioning disc and the mandrel are located in the rubber sleeve; integrated forming of the large-size aluminum oxide ceramic guide rail is achieved, the technical barrier of the manufacturing technology of the large-size aluminum oxide ceramic guide rail is overcome, and the domestic blank is filled up; the qualified large-size aluminum oxide ceramic guide rail for the large-size three-coordinate measuring machine is prepared through ingenious mold design and assembly, a tight sealing process, a novel demolding process and transfer tool design; according to the method, the product percent of pass is increased, and theoretical and technical support is provided for industrialization of the large-size three-hole guide rail.

The invention belongs to the technical field of ceramic material preparation, and particularly relates to a high-throughput preparation method and device based on an aluminum oxide ceramic system diffusion couple. An aluminum oxide model green body containing a plurality of blind holes is prepared through the powder extrusion 3D printing technology, a diffusion material is embedded through a rivet type structure, and the layering risk is eliminated in combination with the thermal expansion coefficient gradient design (the inner layer is large, and the outer layer is small); sPS low-temperature rapid sintering is adopted, and multiple binary diffusion couples are prepared at a time. According to the method, the problems that a traditional diffusion couple is not tight in contact, easy to layer and incapable of being produced in batches are solved, the efficiency is improved by 80% or above, diffusion couple samples of different materials can be prepared at the same time, multiple binary diffusion couple systems can be obtained through subsequent sample cutting, and the preparation method is simple, efficient, easy to operate and suitable for aluminum oxide and rare earth oxide systems.

The invention discloses a stannic oxide-based ammonia gas sensor as well as a preparation method and application thereof, relates to the technical field of gas sensors, and solves the problems of high detection lower limit, poor gas selectivity and low sensitivity of a traditional semiconductor ammonia gas sensor. A sensitive material based on oxygen vacancy regulation and control SnO2 / ZIF-67 is prepared on the surface of an interdigital gold electrode by adopting a chemical vapor deposition method, a planar electrode, an aluminum oxide ceramic substrate, a heater and a Pt wire are welded and packaged according to a general indirectly-heated gas sensitive element, and the SnO2 / ZIF-67 semiconductor ammonia gas sensor is prepared. The lower detection limit of the SnO2 / ZIF-67 semiconductor ammonia gas sensor is 1 ppm; meanwhile, the NH3 selectivity and sensitivity of the sensor are improved through the synergistic effect of SnO2 and ZIF-67, and the sensor can be used for detecting ammonia gas leakage and can be applied to judging the safety of ammonia gas in chemical production operation, environmental gas detection and other applications.

The application belongs to the field of ceramic fibers, and particularly relates to a preparation method of fine-crystal dense alumina ceramic fibers. The application first configures an aluminum sol, an iron sol, a PVP solution and an acidified silica sol, then mixes them according to a set proportion to obtain a mixed sol, concentrates the mixed sol to obtain a spinnable gel, heats the spinnable gel to 500-600 DEG C at a heating rate of 2-10 DEG C / min for pre-sintering after spinning, finally performs microwave sintering at 1000-1400 DEG C at a power of 3000-5000 W and a heating rate of 50-100 DEG C / min to obtain the fine-crystal dense alumina ceramic fibers. The application has simple and controllable process, and the obtained product has excellent performance and is convenient for large-scale industrial application.

The invention discloses an aluminum oxide ceramic tube shell production device and a preparation method, and belongs to the technical field of aluminum oxide ceramic tube shell preparation, the technical scheme is that the aluminum oxide ceramic tube shell production device comprises a forming mechanism, a transferring mechanism, a sintering mechanism and a surface treatment mechanism, the transferring mechanism is used for transferring the formed aluminum oxide ceramic tube shell to the sintering mechanism, the sintering mechanism is used for sintering the formed aluminum oxide ceramic tube shell, and the surface treatment is used for carrying out surface treatment on the sintered aluminum oxide ceramic tube shell. According to the scheme, the adjacent aluminum oxide ceramic tube shells can be uniformly heated, the product quality is ensured, the uniform heating time of the single aluminum oxide ceramic tube shell can be prolonged, repeated sintering is not needed, and the preparation efficiency is improved.

The invention belongs to the technical field of ceramic materials, and particularly discloses whisker toughened zirconium oxide-aluminum oxide composite ceramic and an additive manufacturing method thereof, the composite ceramic comprises the following components by mass: 94 parts of zirconium oxide toughened aluminum oxide ceramic and 5 parts of silicon carbide whisker; the zirconium oxide toughened aluminum oxide ceramic is prepared from the following components in parts by mass: 76 parts of aluminum oxide and 24 parts of zirconium oxide, and 3mol% of yttrium oxide is added into the zirconium oxide. According to the whisker toughened zirconium oxide-aluminum oxide composite ceramic and the additive manufacturing method thereof, the preparation method has unique design of components and process, and the preparation of a high-density and high-performance ceramic-based composite material part based on a fused deposition modeling technology is successfully realized. Further, the prepared silicon carbide whisker toughened zirconium oxide-aluminum oxide-based composite ceramic has relatively high density and excellent obdurability.

The present invention discloses a fully automatic production device and method for forming an alumina ceramic vacuum tube shell, including a material conveying mechanism, a forming mechanism, a transmission mechanism, a stamping mechanism, a grasping mechanism, a turning mechanism, and a placement platform. A forming mechanism is arranged on the transmission mechanism. The material conveying mechanism is used to convey powder materials into the forming mechanism. The transmission mechanism is used to convey the forming mechanism into the stamping mechanism. After stamping, the transmission mechanism conveys the forming mechanism to directly below the grasping mechanism. The grasping mechanism is used to grasp the alumina ceramic vacuum tube shell in the forming mechanism and transport it into the turning mechanism. The turning mechanism is used to perform turning processing on the surface of the alumina ceramic vacuum tube shell. This application can realize the automation of processes such as material conveying, forming, stamping, grasping, turning, and placement, greatly improving production efficiency and product quality, reducing labor costs and energy consumption, and having strong market competitiveness and economic benefits.

The invention discloses a composite material with a shielding function, a preparation method thereof and an interphone shell. The composite material comprises a polycarbonate-acrylonitrile-butadiene-styrene copolymer, a modified conductive filler, maleic anhydride grafted polyethylene, polyaryletherketone, a flame retardant, an antioxidant, glass microfibers and a compatilizer, wherein the modified conductive filler is aluminum oxide ceramic particles subjected to chemical copper plating and graft polymerization treatment. The preparation method comprises the steps of modified conductive filler preparation, step-by-step raw material mixing, twin-screw extrusion granulation and drying. The interphone shell is prepared from the composite material through injection molding, and the injection molding process comprises the steps of raw material drying, injection molding machine preheating, charging and injection molding, and demolding and finishing. The composite material is stable in electromagnetic shielding performance and has good mechanical strength and heat resistance; the preparation method can improve the dispersity of the components and is adaptive to conventional equipment; the interphone shell can block electromagnetic wave interference, is suitable for being used in multiple environments, and meets the requirements of an electronic equipment shell for shielding and structural performance.

The invention relates to the technical field of ceramic materials, in particular to a preparation method of a zirconium oxide toughened aluminum oxide ceramic substrate, which comprises the following steps: 1, pretreating a powder material; step 2, preparing slurry; step 3, tape casting; step 4, stamping and forming; and 5, sintering. Before the slurry is prepared, the aluminum oxide powder and the zirconium oxide powder are uniformly mixed and then subjected to plasma treatment, so that the surface activity of the mixed powder of the aluminum oxide and the zirconium oxide is improved, the grain structure of the mixed powder of the aluminum oxide and the zirconium oxide is changed, and the toughening effect of the zirconium oxide on the aluminum oxide ceramic substrate is improved.

The invention relates to the technical field of ceramic manufacturing processes, and particularly discloses a preparation method of a 96 aluminum oxide ceramic substrate, which comprises the following steps: slurry preparation: carrying out ball milling treatment on high-purity aluminum oxide powder, a sintering aid, a binder, a plasticizer, an organic solvent and a dispersing agent, and fully mixing to obtain tape casting slurry; forming a green body, coating a carrier film with the tape casting slurry through a tape casting machine with a wet film which is uniform in thickness and flat in surface, and drying the carrier film through a drying box in a partitioned manner to obtain a cured green body; and sintering densification treatment: carrying out glue removal treatment on the green body, and carrying out stepped heating sintering to obtain the 96 aluminum oxide ceramic substrate. According to the 96 aluminum oxide ceramic substrate prepared by the scheme, a large number of uniform crystal cores can be formed, small crystal grains can be dissolved, large crystal grains grow at a constant speed, and the uniformity of the crystal grain size is ensured, so that scattering of phonons on a crystal boundary can be reduced, and a structural foundation is laid for improvement of heat conductivity.

The invention discloses a manufacturing method of a small-spacing lamp panel. The manufacturing method comprises the following steps: pressing; drilling is conducted, specifically, through holes are mechanically drilled, and the hole diameter is 0.2-0.3 mm; copper deposition: the thickness of a hole wall copper plating layer is 0.3-0.5 [mu] m; electroplating through holes, wherein the copper thickness in the holes is greater than or equal to 18 microns; the through holes are filled with epoxy resin with the shrinkage rate smaller than 0.5%, and curing is conducted; ceramic board grinding is conducted, an aluminum oxide ceramic grinding wheel is adopted for board grinding, the resin surface in the hole is flush with the surface of the outer layer copper foil of the multi-layer circuit board, the surface roughness Ra is smaller than 0.1 micrometer, and board grinding technological parameters are as follows: the pressure is 5-8 N / cm < 2 >, the rotating speed is 200-300 rpm, and the linear speed is 1-2 m / min; secondary copper deposition: copper deposition is carried out on the surface of the hole plugging resin to form a copper plating layer, and the thickness of the copper plating layer is 0.3-0.5 [mu] m; the whole board is electroplated, and the copper thickness on the resin is larger than or equal to 12 micrometers; and manufacturing an outer-layer circuit. The manufacturing method of the small-spacing lamp panel has the advantages of being low in cost, high in yield, simple in process and the like.

The present invention relates to the field of ceramic technology, and specifically to a high thermal shock alumina composite ceramic and a preparation method thereof, comprising the following raw materials in parts by weight: 65-95 parts of an Al2O3-ZrO2 / ceramic fiber or whisker composition, 100-200 parts of deionized water, 8-12 parts of a plasticizer, and 2-15 parts of a low thermal expansion coefficient base material. The present invention reduces the thermal expansion coefficient of the alumina ceramic by adding ZrO2 / ceramic fiber or whisker to alumina, introducing ceramic fiber or whisker binary toughening while introducing ZrO2 phase change toughening, and introducing a unit with a lower thermal expansion coefficient or a negative thermal expansion coefficient. High-energy ball milling improves the uniformity of the powder interface, thereby improving the thermal shock resistance of the alumina composite ceramic. The method for preparing the ceramic is simple to operate, has high production efficiency, and low production cost. The ceramic round tube made of the alumina composite ceramic can meet the high thermal shock resistance requirements and can be widely used in environments with sudden temperature changes.

The application relates to the technical field of ceramic materials, and provides a SiC-whisker-reinforced alumina ceramic material with whisker directional arrangement and a preparation method thereof. SiC whiskers are magnetically modified by being coated with cobalt, then the magnetically modified SiC whisker powder is mixed with Al2O3 ceramic slurry which has been ball milled, and sodium polystyrene sulfonate is added to the mixture for sufficient mixing in a dispersing machine. Then, an electric field and a magnetic field are simultaneously applied to the mixed solution, so that the SiC whiskers are turned under the action of the electric field and the magnetic field, and directional arrangement of the SiC whiskers in a certain direction is realized. The solution is immediately transferred into a freeze-drying machine to freeze and fix the directional arrangement, and then vacuum sublimation drying is carried out at low temperature, so that the Al2O3-Y2O3-SiC ceramic material with SiC whisker directional arrangement is prepared. w The mixed powder is subjected to hot-pressing sintering to prepare the SiC-whisker-reinforced alumina ceramic material with obvious whisker directional arrangement. The ceramic material can be used for preparing a ceramic cutting tool, and is used for high-efficiency cutting of a nickel-based high-temperature alloy.

The invention discloses a preparation method of high-density aluminum oxide ceramic and the high-density aluminum oxide ceramic, and the preparation method comprises the following steps: adding a silane coupling agent ethanol solution into alpha-Al2O3 powder for modification treatment to obtain modified powder; the modified powder is subjected to doping treatment, doped powder is obtained, and the mass percent of the modified powder in the doped powder is larger than 97.5%; the method comprises the following steps: filling doped powder in a preset range of a key area of a graphite mold, filling pure modified powder on the outer layer of the doped powder, and wrapping carbon felt after pre-pressing and compacting to obtain a pre-pressed sample; the pre-pressed sample is put into a rapid hot-pressing sintering furnace, O2 / Ar mixed atmosphere is introduced, the temperature is gradually increased to a first sintering temperature, and meanwhile, the pressure applied to the mold is gradually increased to the sintering pressure according to the temperature increasing progress; keeping the temperature for a period of time at the first sintering temperature and the sintering pressure; after heat preservation is finished, the sintering pressure is kept, the temperature is reduced to a second sintering temperature, natural cooling is conducted to the room temperature, and the target high-density aluminum oxide ceramic is obtained.

The invention discloses a preparation method of a high-strength aluminum oxide ceramic substrate, which comprises the following steps: firstly, modifying aluminum oxide powder by a liquid phase method, and coating a layer of nano magnesium oxide on the surface of the aluminum oxide powder; then carrying out ball milling treatment on the modified powder, rare earth metal oxide, metal oxide, an organic solvent, a binder, a plasticizer and a dispersing agent together, then carrying out defoaming, tape casting, drying and laminated hot pressing to obtain a ceramic green body, and finally carrying out sintering molding in an air atmosphere to obtain the ceramic. The nano magnesium oxide active coating layer constructed in situ and the added exogenous sintering aid act together, so that uniform growth of isometric crystals is promoted, development of a small amount of dominant oriented grains is directionally induced, a composite enhanced microstructure is formed, atomic scale super-uniform distribution and optimal interface combination of the nano magnesium oxide and the exogenous sintering aid are realized, and the nano magnesium oxide / exogenous sintering aid composite material is prepared. The bending strength of the obtained alumina ceramic can reach up to 881 MPa.

The invention relates to the technical field of preparation of alumina ceramic materials, in particular to an alumina-based porcelain insulator porcelain body and a preparation method thereof. The alumina-based porcelain insulator porcelain body is prepared from interface repair type alumina and a sintering aid, the mass ratio of the interface repair type aluminum oxide to the sintering aid is 100: (5-10); the sintering aid is at least one of zirconium oxide, rare earth oxide, calcium oxide, magnesium oxide, silicon dioxide and manganese dioxide; the interface repair type aluminum oxide is interface metal atom repair type aluminum oxide, the interface metal atom repair type aluminum oxide comprises carrier aluminum oxide and metal atoms anchored at defect points of the carrier aluminum oxide in a monatomic form, and the metal atoms at least comprise Al. The alumina-based porcelain insulator porcelain body has the advantages of small dielectric constant and low dielectric loss, and meets the electrical performance requirements of extra-high voltage power transmission on insulators.

The invention discloses a chemical cleaning reagent for aluminum oxide ceramic parts and a cleaning method. The chemical cleaning reagent comprises organic acid, a surfactant, a chelating agent, an oxidizing agent and deionized water. Aiming at the special pollution problem (such as trace metal ions, nano-scale particles and organic matters) of the aluminum oxide ceramic part in the 14-nm manufacturing process, the chemical cleaning reagent formula is optimized, pollutants on the surface of the ceramic part can be efficiently removed, and the cleanliness requirement of the 14-nm manufacturing process is met. The cleaning method comprises the steps of pretreatment, chemical cleaning, rinsing and drying, has the advantages of environmental protection, safety and no damage to the ceramic surface, and is suitable for the field of semiconductor manufacturing.

The invention provides porous alumina ceramic and a preparation method thereof, and relates to the technical field of ceramic materials. The invention relates to a preparation method of porous alumina ceramic. The preparation method comprises the following steps: dispersing alpha-cellulose powder in deionized water to form a cellulose suspension; stirring to fully swell the cellulose and form uniform gel, and freeze-drying to obtain a template; dissolving aluminum nitrate hexahydrate, magnesium nitrate hexahydrate and yttrium nitrate hexahydrate in absolute ethyl alcohol to obtain a precursor solution; putting gamma-Al2O3 micro powder and ammonium fluoride into a ball milling tank, adding the precursor solution and a dispersing agent, adding zirconium oxide balls and absolute ethyl alcohol into the ball milling tank, and performing ball milling to obtain ceramic slurry; dipping a template into the ceramic slurry, and performing dipping treatment under a vacuum condition to form a composite green body; and sintering to obtain the porous alumina ceramic. According to the porous aluminum oxide ceramic, the process stability is improved, and the problem that the strength is sharply reduced when the porosity is too high is solved.

The invention relates to the field of advanced ceramic materials, in particular to a ceramic matrix composite (CMC) and a preparation method thereof. The technical problems that a traditional CMC preparation technology is long in period, poor in structural uniformity and insufficient in toughness are solved. According to the method, surface-modified aluminum oxide ceramic microspheres are used as reinforcements, the surfaces of the microspheres are sequentially modified with hexagonal boron nitride nanosheets and a metal nickel catalyst, the microspheres, silicon carbide nanoparticles and a polycarbosilane precursor are mixed to form slurry, and a complex component is formed through multi-material additive manufacturing. A green body is prepared by using a 3D printing technology combining photocuring and material extrusion; carrying out ultraviolet curing on the green body, and carrying out staged heat treatment in an inert atmosphere, so that the precursor polymer is subjected to cross-linking curing, and meanwhile, carbon nanowires grow through in-situ catalysis; and finally, sintering under a pressurizing condition to realize matrix densification. The preparation period is greatly shortened, and the obtained composite material is uniform in structure, compact in matrix and excellent in mechanical property.

The invention relates to the technical field of material sealing, in particular to a high-performance insulating ceramic sealing method for a neutron tube, which comprises the following steps: sequentially carrying out organic solvent ultrasonic cleaning and argon plasma etching activation treatment on a sealing surface of a cylindrical high-purity aluminum oxide ceramic piece, and depositing a titanium transition layer through magnetron sputtering, the ceramic piece with the titanium transition layer is obtained; the sealing face of the kovar alloy cylindrical flange plate is subjected to acid pickling, an oxide layer is removed, cleaning and drying are conducted, and a metal sealing part is obtained; preparing an active brazing filler metal sheet; the components are assembled in sequence to form a pre-assembled component; the pre-assembled component is placed in a vacuum brazing furnace, axial pre-tightening force is applied to the pre-assembled component, sealing is completed, then cooling is controlled, and a sealing piece with an airtight brazing joint is formed; and carrying out annealing treatment to obtain a finished product sealing assembly. Therefore, the problems of low dielectric strength, large thermal expansion coefficient difference, difficulty in interface quality control and the like in the prior art are solved.

The invention provides a method for manufacturing a high-strength aluminum oxide ceramic substrate, which comprises the following steps of: performing aluminum oxide particle surface heat treatment rounding on low-cost calcined and crushed aluminum oxide, adding at least one of a magnesium-containing compound, an yttrium-containing compound and a barium-containing compound into the rounded aluminum oxide powder, and adding into a solvent; the preparation method comprises the following steps: fully mixing the raw materials with slurry prepared from a dispersing agent, an adhesive and a plasticizer by virtue of a high-effect bead mill, dispersing, degassing, forming a green body, punching, carrying out two-stage sintering treatment and the like, thereby obtaining the high-density and high-strength composite material which is excellent in density and high in strength. The aluminum oxide substrate with thermal, electrical and mechanical properties, such as surface smoothness roughness of less than 0.05 mu m, high thermal conductivity (K) of more than 30W / mK, insulation characteristic of more than 1014 omega.cm, three-point breaking strength of more than 600MPa, and the like, is prepared from the aluminum oxide substrate.