227results about How to "Homogeneous microstructure" patented technology

The invention relates to a process for preparing ZrB2-SiC-ZrC complex phase ceramic materials, which is characterized in that purity of zirconium powder is not less than 98%, silicon powder and boron carbide powder are used as raw materials, batching according to reaction equation (2+x)Zr+(1-x)Si+B4C=2ZrB2+(1-x)SiC+ZrC, 0<=x<=0.5 of generating ZrB2-SiC-ZrC, then, materials containing different components are obtained. The raw materials after being ball ground and dried are sintered with heat pressing between 1500-1700DEG C by adjusting sintering technique parameter and employing self-propagating reaction of the raw materials generated in the process of heating up, thereby obtaining the ZrB2-SiC-ZrC complex phase ceramic materials of different components. Relative density of the materials prepared by the invention is larger than 97%, bending strength is 600-900MPa, fracture toughness property is 4.5-6MPa,m1/2, and hardness is 16-19GPa.

The invention relates to a high potential gradient zinc oxide pressure-sensitive resistor material and a preparation process thereof. The high potential gradient zinc oxide pressure-sensitive resistor material with uniform particle sizes is obtained by weighing a main material ZnO, a doping oxide, and a product rare earth oxide obtained by carrying out thermal decomposition on a rare earth oxalate or/and carbonate or/and hydroxide according to proportions, carrying out high energy wet grinding, drying, presintering at 200-800DEG C, carrying out high energy dry grinding, and sintering at 800-1100DEG C. The preparation process of the invention has the advantages of simplicity, low cost, environmental protection and low energy consumption, and the prepared zinc oxide pressure-sensitive resistor material can be used for preparing high quality lightning arrester products for ultrahigh electric power systems.

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.

The invention relates to a sintering aid for yttrium aluminum garnet-based fluorescent transparent ceramic and a using method thereof. The sintering aid particularly comprises tetraethoxysilane and magnesium oxide, wherein the using amount of the tetraethoxysilane with the silicon oxide content of not less than 28.4 percent is 0.3 to 0.7 weight percent of the garnet-based transparent ceramic fluorescent powder raw material; and the using amount of the magnesium oxide with the purity of not less than 99.9 percent is 0.01 to 0.8 weight percent of the garnet-based transparent ceramic fluorescent powder raw material. The garnet-based transparent ceramic fluorescent material prepared from the sintering aid has a compact microstructure and is uniform in crystallite dimension distribution.

The invention belongs to the field of powder metallurgy, and particularly relates to mixed powder for an electric tool and a preparation method thereof. The mixed powder is characterized by being prepared by mixing and bonding water-atomized diffused alloy powder with water-atomized pure iron powder, graphite powder, copper powder and a lubricating agent in a segregation-free way, wherein the ratio of components by weight percentage as follows: 50-55 percent of water-atomized diffused alloy powder, 0.4-0.5 percent of graphite powder, 0.3-0.35 percent of copper powder, 0.7-0.8 percent of lubricating agent and the rest of water-atomized pure iron powder. The preferable ratio is as follows: 50 percent of water-atomized diffused alloy powder, 0.5 percent of graphite powder, 0.35 percent of copper powder, 0.7 percent of lubricating agent and the rest of water-atomized pure iron powder. Compared with the prior art, the mixed powder has the advantages that 1) the mix powder has over 7.05g/cm3 of compressed density; 2) alloy elements cannot be segregated in the transport and mixing treatment process; and 3) the mechanical performance of sintering parts is effectively improved.

The invention relates to a method for preparing an MgAlON transparent ceramic bisque by gel casting and molding. The method comprises the steps of: 1) preparing a pre-mixed solution; 2) preparing ceramic slurry; 3) casting and molding; 4) drying and degreasing a billet, and finally obtaining the MgAlON ceramic bisque. The MgAlON ceramic bisque prepared by the method is smooth in surface, intact in shape, and uniform in microscopic structure; the bending strength of a dried billet is greater than 10MPa, and the micro-structure and mechanical property of a sample are superior to those of the ceramic bisque prepared by the other traditional ceramic molding methods.

The invention discloses high-strength silicon carbide foam ceramic and a one-time pulp hanging carburizing sintering preparation method thereof, and belongs to the technical field of silicon carbide foam ceramic preparation. The method comprises the steps that foamed plastic serves as a template, a one-time pulp hanging carburizing sintering method is adopted, high-char polymer resin, silicon powder, sintering aids and ethyl alcohol are mixed to be prepared into pulp with certain viscosity, the foamed plastic is immersed in the pulp and then taken out, then surplus pulp is removed through a centrifugal method, drying is conducted in the shade, and then pulp hanging is repeated until the needed volume fraction is reached; a foam precursor obtained after pulp hanging is put into a tubular furnace to be subjected to pyrolysis carbonization in a nitrogen or argon atmosphere, a foam ceramic carbon precursor framework formed by pyrolytic carbon, the silicon powder and the sintering aids is obtained, the foam ceramic carbon precursor framework is put in an atmosphere furnace to be sintered, and the high-strength SiC foam ceramic is obtained. Compared with a traditional template method, the method is simple in technology, mild in reaction condition, low in equipment requirement and capable of achieving large-scale production easily.

The invention discloses a preparation method of high-porosity silicon-carbide porous ceramics. According to the preparation method, 60 to 80% of silicon-carbide powder, 10% of boron carbide, 5 to 25% of iron oxide and 5% of polyvinyl alcohol by weight are adopted as raw materials, and the steps of mixing, spray granulation, extrusion forming, drying and sintering are sequentially carried out, wherein the technical conditions for sintering are as follows: a dried biscuit is sintered for 10 to 15 hours at 2100 to 2200 DEG C through pressureless sintering technology so as to obtain the high-porosity silicon-carbide porous ceramics. The silicon-carbide porous ceramics prepared by the method disclosed by the invention has the characteristics of controllable aperture size, high apparent porosity, and relatively large specific surface area, and strength of the silicon-carbide porous ceramics meets the application requirement.

The invention discloses a density enhancing method of piezoelectric ferroelectric ceramic materials with bismuth layer structure. According to a chemical formula: (Am-1BmO3m+1) <2-> (Bi2O2) <2+>; and molar ratio A: B: Bi = m-1: m : 2, materials are calculated and weighted, wherein, the A is univalent, bivalent, trivalent or quadrivalent metal ion that is suitable for dodecahedral coordination; the B is trivalent, quadrivalent, pentavalent or sexivalent metal ion that is suitable for octahedral coordination; the production processes are that: mixing, pre-synthesizing, grinding, forming and sintering; the sintering process is that: the temperature of the obtained material from the last step is raised to 1100 to 1250 DEG C at a speed of 2 to 5 DEG C per minute, and is lowered to 50 to 150 DEG C within 1 to 5 minutes; under the temperature of 950 to 1150 EDG C, insulation at the low temperature is done for 5 to 20 hours; then the temperature is lowered to 500 DEG C at a speed of 3 to 7 DEG C per minute, and the obtained material is naturally cooled with a furnace. The invention can obtain the piezoelectric ferroelectric ceramic materials with grain-refining and density bismuth structure.

The invention relates to an in-situ (TiB2+SiC)/Ti3SiC2 complex phase ceramic material. The in-situ (TiB2+SiC)/Ti3SiC2 complex phase ceramic material is characterized by consisting of a laminated Ti3SiC2 matrix and two reinforced phases of columnar TiB2 and granular SiC, wherein the TiB2 accounts for 13 to 15 percent of the total volume of the complex phase ceramic material; and the SiC accounts for 5 to 15 percent of the total volume of the complex phase ceramic material. A preparation method of the in-situ (TiB2+SiC)/Ti3SiC2 complex phase ceramic material comprises the following steps of: weighing TiH2 powder, Si powder, TiC powder, B4C powder and Al powder according to the molar ratio of the TiH2 powder to the Si powder to the TiC powder to the B4C powder to the Al powder of (0.9-1.3):(1):(1.4-1.6):(0.15-2.1):(0.13-0.16); mixing the raw materials uniformly; putting the mixture into a graphite mould to perform cold moulding; and performing hot pressed sintering in a graphite resistance furnace under protective atmosphere. The process is simple and the material has excellent properties.

The invention discloses a ceramic material sintering furnace and an isostatic pressing field-controlled spark pulse sintering method, namely isostatic pressing and spark pulse field controlled sintering for short. The isostatic pressing and spark pulse field controlled sintering is characterized by comprising preparation of a ceramic blank, an isostatic pressing and spark pulse field controlled sintering furnace, processing of a ceramic sintering body, and an isostatic pressing and spark pulse field controlled sintering method, wherein the isostatic pressing and spark pulse field controlled sintering furnace comprises a lower furnace body, a thermocouple, an upper furnace body, an electrode plate, an bench insulator, an electrode lead, a graphite packing, a control electric field, a rubber seal cartridge, an insulating ring adaptor, a pressure gauge, a gas cylinder, a gas valve, a compressor, a gas inlet, a gas outlet, an impulse current generator, a sintering controller and fixing support feet, the isostatic pressing and spark pulse field controlled sintering method enables the transfer and direction of the heat energy, pressure and electromagnetic field of macroscopic and microcosmic ceramic materials to tend to be uniform due to the application of the discharge plasma pulse currents and alternating electromagnetic fields on the blank and the comprehensive action of gas isostatic pressing, the ceramic material is uniformly and isotropously sintered in the microcosmic crystal lattice, the grain boundary and the dot matrix, so that the various performances of the sintered structural ceramic material are improved.

The invention relates to a nickel ferrite-copper metal ceramic inert anode material which comprises a ceramic phase and a metal phase, wherein the ceramic phase is nickel ferrite or nickel ferrite base composite ceramic; and the metal phase consists of metal copper and cuprous oxide, and the cuprous oxide accounts for 1-20% of the total mass of the metal phase. In the preparation process, the content of the cuprous oxide in the metal phase is controlled through controlling the oxygen partial pressure of a nitrogen protection atmosphere so as to improve the wettability of the nickel ferrite and the copper and achieve the sintering infiltration preparation of the ceramic phase and the metal phase. The metal phase and the ceramic phase of the nickel ferrite-copper metal ceramic inert anode material are in a three-dimensional reticular through structure, wherein the sintering density is higher than 98%, the electric conductivity of the metal ceramic material is more than 200S/cm at a temperature of 900 DEG C, the heat conductivity is up to 40W/(m.K) at the room temperature, and the metal ceramic material cannot be cracked through temperature difference thermal shock at the temperature of 400 DEG C. The problems of difficult sintering densification of the nickel ferrite and the copper, sintering overflow of the metal phase and material thermal shock and cracks are effectively solved, and compared with a material prepared by a conventional mixed powder sintering process, the electric conductivity and the thermal shock resistance of the nickel ferrite-copper metal ceramic material are greatly improved.

The invention discloses a method for preparing silicon nitride bonding silicon carbide foamed ceramics. The method is characterized by comprising the following steps: uniformly mixing SiC, silica powder, a phenolic resin and hydroxypropyl methyl cellulose solution so as to prepare ceramic slurry; dipping the ceramic slurry on polyurethane foam, drying, and firing in a nitrogen atmosphere, thereby obtaining the silicon nitride bonding silicon carbide foamed ceramics. The silicon nitride bonding silicon carbide foamed ceramics prepared by the method are uniform in microstructure, high in strength and uniform in pore size, and residues of carbon and free silicon are avoided, so that the strength, high temperature resistance and thermal shock resistance of the ceramics can be greatly improved.

The invention provides a curing method used for radioactive nuclear waste simulation matter, which is characterized in that the method comprises the steps as follows: SiO2, ZrO2, and Eu2O3 or CeO2 are taken as raw material and compounded, grinded, dried and calcinated for 20-25h under the temperature of 1400-1600 DEG C so as to prepare a solidified body which takes the zircon as the substrate. The preparation method of the invention has the advantages of simple method, easy operation, short production period, high production efficiency, and uniform solidified body microstructure with higher crystallinity; the method of the invention is a new effective curing method provided for processing the radioactive nuclear waste and can be widely used for the processing of the radioactive nuclear waste exhausted by corresponding fields such as nuclear industry, etc.

The invention relates to a method for preparing foamed ceramic through hydrophobic flocculation. The method comprises the steps that the solid content is controlled to be 15-50 vol.%, the pH value of water-based ceramic slurry is regulated to enable the surface of ceramic powder to be electrically charged so as to be uniformly dispersed in an electrostatic repulsion mode; surfactant of which an electric charge type is opposite to that of the ceramic powder surface is added into the water-based ceramic slurry, stirring or ball-mill mixing is conducted to enable the surfactant to be uniformly dispersed or adsorbed on the ceramic powder surface, and surfactant modified partially-hydrophobic ceramic slurry is obtained; the partially-hydrophobic ceramic slurry is subjected to mechanical stirring foaming, foam slurry is directly injected into a mold, the room-temperature in-situ solidification, then demoulding and drying are conducted, and after sintering is conducted, the foam ceramic is obtained. According to the method, by means of electrostatic repulsion, ceramic particles in the slurry reach a good dispersion effect, and the water based ceramic slurry which is low in viscosity and good in flowability is obtained.

The invention relates to a method for preparing SiC/TiC composite ceramic by a precursor method. The method of the invention is characterized by comprising the following steps: (1) fully dissolving PCS with a solvent so as to prepare a PCS transparent solution; adding Ti powder; heating, stirring and removing the solvent by steaming until the system is hard to stir; and drying to obtain a mixture of PCS (polycarbosilane) and Ti powder; (2) carrying out high-temperature pyrolysis on the mixture of PCS and Ti powder in a high temperature furnace in the inert atmosphere so as to obtain a SiC/TiC composite powder; and (3) carrying out hot pressed sintering densification on the SiC/TiC composite powder to obtain the SiC/TiC composite ceramic. The technology of the method is simple; sintering temperature is low; and the prepared SiC/TiC composite material has uniform microstructure, fine grain size and high hardness.

The invention relates to an O-Sialon porous material prepared by gel-casting and a preparation method thereof. The preparation method mainly comprises the following steps: preparing suspensoid slurry, preparing a green body, drying, exhausting rubber and sintering. Alpha-Si3N4, Al2O3, SiO2, Y2O3, MgO and h-BN are taken as raw materials, and the O-Sialon porous material is prepared by a way of combining gel-casting and adding of hard-to-sinter phase (h-BN) of a second phase through an in-situ synthesis technology; the O-Sialon porous material has the density of 1.1 g.cm<-3>-1.6 g.cm<-3>, the porosity between 46% and 64%, the room temperature three-point bending strength between 30 MPa and 82 MPa, a dielectric constant between 2.1 and 4.5, and a tangential value of dielectric loss between 0.112*10<-3>-0.702*10<-3>.

The invention discloses a preparation method for slip casting of a high-density AZO target material. The preparation method comprises the following steps that zinc oxide powder and aluminum oxide powder are evenly mixed to obtain mixed materials, the mixed materials are added into a nylon tank, a dispersing agent and water are added, and a pH value is regulated to 8.5-10.3 by using ammonia water or acetic acid; the premixed solution is subjected to ball milling to prepare suspension liquid slurry; the slurry obtained through ball milling is subjected to vacuum degassing, the slurry obtained after vacuum degassing is injected into a plaster mold; demolding is performed after slurry sucking and molding, a blank is air-dried for more than 72 hours; degreasing is performed after curing to obtain an AZO blank; the blank is sintered to obtain the AZO target material. A slip casting forming process and a pressure-less AZO target material sintering process are adopted, and the high-density AZO target material can be prepared in a low-cost mode.