265 results about "Pressureless sintering" patented technology

The invention discloses pressureless sintered aluminum nitride ceramic as well as a preparation method and application thereof. The preparation method comprises the following steps: ball-milling and mixing micron-sized aluminum nitride, a sintering aid, nano-sized molybdenum powder, a dispersing agent, a binder and an organic solvent to prepare slurry; and drying the slurry, granulating, forming, dumping and sintering to obtain the pressureless sintered aluminum nitride ceramic. Wherein the sintering aid is a combination of samarium fluoride and yttrium fluoride. According to the preparation method, oxygen is removed at a low temperature by virtue of strong affinity of the nanoscale molybdenum powder and oxygen, the nanoscale molybdenum powder and the sintering aid jointly play a role in liquid-phase sintering assistance at a high temperature, densified sintering is realized and grain growth is inhibited by adopting pressureless sintering at a relatively low sintering temperature, the aluminum nitride ceramic with both heat conduction and strength is obtained, and meanwhile, a low-resistance second phase is generated; the resistivity of the aluminum nitride ceramic is adjusted while the heat conduction characteristic of the aluminum nitride ceramic is improved, the electrical conductivity of the aluminum nitride material is improved, and finally the aluminum nitride ceramic with high heat conduction and bending strength and moderate resistivity is obtained to meet the use requirements of electrostatic chucks.

The invention relates to a preparation method of a high-precision gel injection pressureless sintering silicon carbide ceramic water jet cutter sand pipe, which comprises the following steps: pouring premixed liquid into a mold, and curing to obtain a green body; the inner mold is taken out of the cured blank, then the outer mold and the blank are put into a polyethylene glycol solution to be dried, the blank shrinks when being dried in the polyethylene glycol solution, and demolding is completed; drying the demolded green body on drying equipment, and carrying out vacuum heating to obtain a dried green body; and carrying out pressureless sintering on the dried blank to obtain the silicon carbide ceramic water jet cutter sand pipe. The premixed liquid comprises a monomer, a cross-linking agent, a dispersing agent, a defoaming agent, modified silicon carbide powder, a sintering aid and tetramethylammonium hydroxide, and the modified silicon carbide powder comprises graphene composite silicon carbide and modified carbon nanotubes. The water jet cutter sand pipe has the effect of improving the product quality of the prepared water jet cutter sand pipe.

The preparation process comprises the following steps: dissolving ammonium dimolybdate, ammonium rhenate and water at a high temperature, then adding zirconium hydroxide, uniformly mixing, carrying out vacuum drying, carrying out two-stage hydrogen reduction on the obtained precursor composite powder, and carrying out vacuum drying to obtain the zirconium dioxide reinforced phase-containing molybdenum-rhenium alloy capable of inhibiting abnormal growth of crystal grains, thereby obtaining the zirconium dioxide reinforced phase-containing molybdenum-rhenium alloy capable of inhibiting abnormal growth of crystal grains. Zirconium oxide reinforced molybdenum-rhenium composite powder obtained after reduction is subjected to cold isostatic pressing, pressureless sintering and hot isostatic pressing to obtain zirconium oxide reinforced molybdenum-rhenium alloy, and then the zirconium oxide reinforced molybdenum-rhenium alloy is obtained through high-temperature rolling and recrystallization annealing treatment. According to the method, atomic-level mixing of molybdenum and rhenium is achieved through liquid-phase doping, the microstructure of the molybdenum-rhenium alloy is more uniform and fine due to addition of ZrO2, the recrystallization temperature is increased, and the phenomenon that sintered grains of the molybdenum-rhenium alloy grow abnormally is relieved. And by optimizing the annealing process and regulating and controlling the annealing mode, grains are rearranged to form a more uniform microstructure, abnormal growth of the grains is further inhibited, and the high-temperature tensile strength and the ductility of the molybdenum-rhenium alloy are improved.

The invention provides a molybdenum-based oxide sintered body, a sputtering target material containing the sintered body, and an oxide thin film formed by the sputtering target material. In the present invention, a specific dopant is added to a molybdenum oxide and a niobium oxide that are difficult to sinter in a prescribed content range, and it is possible to simultaneously ensure improved sinterability, high density characteristics, and uniformity, low reflection, and low resistance characteristics of a thin film obtained by controlling particle growth even if pressureless sintering is performed.

The invention relates to a hard alloy micro-texture tool based on discharge plasma pressureless sintering and a preparation method. Comprising the following steps: preparing a micro-texture male die pressing head; wC-Co mixed powder is obtained; the pressure head in the step (1) is adopted to apply 150-180 MPa pressure to the WC-Co mixed powder, the pressure is maintained for 60 min, and a biscuit is obtained after demolding; putting the biscuit into a graphite mold, assembling the mold, carrying out vacuum pressureless sintering on the biscuit, heating to 1300-1400 DEG C at the heating rate of 90-110 DEG C / min, carrying out heat preservation for 10 + / -2 minutes, and then cooling to room temperature along with a furnace to obtain a hard alloy block with a micro-texture on the surface; and the micro-texture surface of the hard alloy block is only polished to be bright. According to the method, thermal damage and fusion edge collapse are thoroughly avoided, and high-precision, namely high geometric fidelity, high efficiency, namely short sintering period and low-cost preparation of the microstructure is realized.

The invention relates to the technical field of silicon carbide ceramics, in particular to a preparation method and a sintering device of a large-sized pressureless sintered silicon carbide ceramic tubing, and the preparation method comprises the following steps: uniformly mixing beta-type silicon carbide whiskers, graphite powder, boron carbide, a sintering aid, a dispersing agent, a binder and silicon carbide micro powder, then adding water, and stirring to prepare pug with the water content of 32-38%; pugging is conducted till pug with the water content being 8%-11% is obtained, and then the pug obtained after pugging is sealed and aged at the room temperature; carrying out extrusion molding on the aged pug through a vacuum extruder to obtain a ceramic tube blank; the ceramic blank pipe is fed into drying equipment to be dried; and sintering the ceramic blank tube in a nitrogen atmosphere at 1900-2150 DEG C to obtain the silicon carbide ceramic tube. By adding the beta-type silicon carbide whiskers, the silicon carbide micro powder, the sintering aid and other substances, the toughness and strength of the silicon carbide ceramic pipe can be enhanced, the wall thickness of the pipe can be reduced on the premise of keeping the same strength level, thermal resistance can be reduced, and the heat exchange efficiency of a heat exchanger can be improved.

The invention discloses a ceramic material for a high-temperature water-oxygen environment and a preparation method of the ceramic material, and belongs to the technical field of environmental barrier coatings. According to the preparation method disclosed by the invention, the Al2O3 modified Yb2Si2O7 powder is prepared into the tablet with a certain size and shape by a dry pressing method, and finally the tablet is sintered into the ceramic material by a pressureless sintering method in the atmosphere, so that the obtained ceramic material for the high-temperature water-oxygen environment can meet the application in the high-temperature water-oxygen environment of 1500 DEG C, has excellent high-temperature environment use performance, and is suitable for being used in the high-temperature water-oxygen environment. And the requirement of a thermal protection component on a C / C composite material high-temperature environment barrier coating is met.

The invention provides a method for preparing a zirconium boride ceramic material through pressureless sintering, and belongs to the technical field of zirconium boride ceramics. The method comprises the steps of preparing zirconium boride composite powder, modifying silicon carbide nanowires and mixing and sintering. The method for modifying the silicon carbide nanowire comprises the steps of acid treatment and modification, the modification step comprises the following steps: adding aluminum isopropoxide into absolute ethyl alcohol, adding a nitric acid solution, stirring for 1.5-2.0 hours at the temperature of 60-63 DEG C, adding the acid-treated silicon carbide nanowire, carrying out ultrasonic dispersion and water bath evaporation, then drying, putting into a muffle furnace, and carrying out heat preservation for 2.0-2.2 hours at the temperature of 490-500 DEG C to obtain a modified silicon carbide nanowire; the ceramic material prepared by adopting the method disclosed by the invention is high in density, good in mechanical property and excellent in high-temperature oxidation resistance and stability in a complex environment.

The invention relates to a method for preparing MgAlON ceramic with high infrared transmittance by utilizing coarse powder pressureless sintering, and belongs to the field of ceramic preparation. A method for preparing MgAlON ceramic with high infrared transmittance by utilizing pressureless sintering of coarse powder comprises the steps that pure-phase MgAlON powder and a sintering aid are subjected to ball-milling mixing, drying and granulation to obtain mixed powder of MgAlON and the sintering aid, the mixed powder is formed and subjected to pressureless sintering in the nitrogen atmosphere to obtain the MgAlON ceramic, the atomic ratio of Mg to Al to O to N in the pure-phase MgAlON powder is 1: (10-20): (15-25): (2-4), and the atomic ratio of Mg to Al to O to N in the sintering aid is 1: (10-20): (15-25): (2-4). The D50 of the mixed powder of the MgAlON and the sintering aid is 1.1-2.0 [mu] m, and the particle size distribution range is 0.2-10 [mu] m. According to the method, the difficulty of a ball-milling process is small, the risk that impurities are introduced due to particle refinement can be effectively reduced, sintering equipment is easy to obtain, the heat preservation time in the pressureless sintering process is short, the obtained ceramic is high in infrared transmittance, good in energy-saving effect, high in efficiency, low in cost and suitable for preparation of large-size and complex-shape sample pieces, and industrialization is easy to achieve.

The invention discloses a carbon-doped non-noble metal high-entropy alloy hydrogen evolution catalytic electrode and a preparation method thereof, and belongs to the technical field of water electrolysis hydrogen production. The preparation method comprises the following steps: (1) blending four metal powder of Fe, Co, Ni and Mo with carbon powder, ball-milling, standing and passivating to obtain mixed powder; and (2) carrying out compression molding on the mixed powder obtained in the step (1), and sintering. The preparation method is simple in process, the hydrogen evolution catalytic electrode can be obtained only through two steps of mechanical alloying and pressureless sintering, operation is easy and convenient, large-scale preparation can be achieved, and industrialization is easy; through a carbon doping mode, a transition metal carbide-molybdenum carbide and quaternary high-entropy alloy synergistic effect is formed in the electrode material, the free energy of a hydrogen intermediate is obviously reduced, the mass transfer process in electrochemical reaction is facilitated, and the electrode material has excellent hydrogen evolution catalytic performance and is suitable for water electrolysis hydrogen evolution catalytic reaction in an alkaline environment; the hydrogen production efficiency can be improved, and the energy consumption is reduced.

The invention provides a black aluminum oxide ceramic material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing aluminum oxide, magnesium oxide, silicon dioxide, iron oxide, manganese oxide, chromium oxide and a solvent to obtain an aluminum oxide ceramic mixed solution; (2) mixing the alumina ceramic mixed solution with a binder, and grinding to obtain alumina ceramic powder; and (3) carrying out cold pressing treatment on the aluminum oxide ceramic powder, and carrying out vacuum pressureless sintering treatment to obtain the black aluminum oxide ceramic material. The black aluminum oxide ceramic material prepared by the method disclosed by the invention is relatively small in crystal grain, relatively small in pore and relatively high in density, and has relatively high compactness and thermal conductivity.

The invention relates to the technical field of preparation of silicon carbide ceramic special-shaped beams, in particular to a pressureless sintered silicon carbide ceramic special-shaped beam and a preparation method thereof.The pressureless sintered silicon carbide ceramic special-shaped beam comprises the following components and structures: material composition: a base material is silicon carbide powder, the particle size is in bimodal distribution, a main phase is 3-5 microns, and a nanophase is 0.5-1 micron; a composite sintering aid; through innovative design of material composition and structure, multi-scale synergistic reinforcement and surface gradient protection are realized, bimodal distributed silicon carbide powder is adopted as a matrix, and through the synergistic effect of a micron-sized particle skeleton and nano-particle filling pores, internal cracks caused by uneven shrinkage of a special-shaped section are remarkably reduced, so that the surface gradient protection performance is improved. And meanwhile, the composite sintering aid can inhibit abnormal growth of crystal grains, synergistically reduce the sintering temperature and reduce the deformation risk of the multi-cavity structure, the crack propagation resistance of the corner angle is greatly improved through the gradient reinforcement phase, and the problem that a hardened layer at the special-shaped corner angle is not uniform is solved through deep siliconizing reinforcement.

The invention discloses Si-based MAX phase powder and a preparation method thereof, and belongs to the technical field of ceramic material preparation. The preparation method of the Si-based MAX phase powder comprises the following steps: mixing a transition metal source, polysiloxane, a solvent, a curing agent and a platinum catalyst to obtain a mixed solution; the curing agent is vinyl modified siloxane; heating and curing the mixed solution to obtain a solid precursor; and crushing the solid precursor into powder, and then carrying out pressureless sintering in a protective atmosphere, thereby obtaining the product. According to the method, subsequent ball milling and other procedures are omitted, and impurity introduction to the product is avoided. According to the invention, the operation difficulty is greatly reduced, the production efficiency is improved, the energy consumption is reduced, and large-scale and low-cost production is realized.

The invention relates to the technical field of silicon carbide ceramics, in particular to a preparation method of pressureless sintering extrusion type silicon carbide ceramics, which comprises the following steps: putting deionized water, silicon carbide micro powder, hexagonal boron nitride, aggregate, graphite, a dispersing agent, a sintering aid and a binder into a stirring kettle; vacuumizing with a vacuum pump, and mixing and stirring to obtain slurry; filtering the slurry, and preparing granulated micro powder through a spray drying method; preparing the granulated micro powder into a green body through a powder extrusion printing technology; feeding the green body into drying equipment for drying; the dried green body is wrapped with a layer of graphite felt, and the green body and the graphite felt are sent into a sintering furnace; and after sintering, cooling to room temperature to obtain the silicon carbide ceramic product. According to the method, the pressureless sintering technology is adopted, external pressure does not need to be applied, and the production cost and the equipment complexity are reduced; the green body is prepared through the powder extrusion printing technology, and the precision and shape complexity of the product are improved.

The invention belongs to the technical field of transparent ceramics, and discloses a high-entropy transparent ceramic and a preparation method and application thereof. The molecular formula of the high-entropy transparent ceramic is (LuxYySczYbmErn) 2O3, x is more than or equal to 0.05 and less than or equal to 0.6, y is more than or equal to 0.05 and less than or equal to 0.6, z is more than or equal to 0.05 and less than or equal to 0.6, m is more than or equal to 0.05 and less than or equal to 0.6, n is more than or equal to 0.05 and less than or equal to 0.6, and x + y + z + m + n is equal to 1, Lu2O3 powder, Y2O3 powder, Sc2O3 powder, Yb2O3 powder, Er2O3 powder and ZrO2 powder are subjected to ball milling and mixing, calcined and molded at 800-1200 DEG C to prepare a biscuit, and the biscuit is subjected to pressureless sintering at 1600-1800 DEG C in vacuum, annealed and polished to prepare the high The relative density of the ceramic is 99.5% or above, the transmittance at 1000 nm is 76% or above, and the ceramic has good optical, mechanical, corrosion-resistant and radiation-resistant performance and can be applied to the field of nuclear energy window material preparation.

The invention discloses a high-wear-resistance FeZr-ZTA micro powder coated ZTA ceramic reinforced high-chromium cast iron-based composite material as well as preparation and application thereof. The preparation method comprises the following steps: firstly, ball-milling Zr-Fe powder and ZTA micro powder into a mixed powder binder, wrapping the mixed powder binder on the surfaces of ZTA particles, pre-sintering at 1000-1200 DEG C, then mixing pre-coated ZTA particles with the binder to coat the surfaces of the pre-coated ZTA particles, and carrying out pressureless sintering to obtain a ZTA ceramic preform; and finally, the ZTA ceramic particle reinforced high-chromium cast iron composite material is obtained through a casting infiltration method. Through the bridge action of the FeZr-ZTA micro powder coating layer, a metallurgical bonding interface can be formed between ZTA and a high-chromium cast iron matrix, so that the prepared ZTA ceramic particle reinforced high-chromium cast iron composite material has excellent three-body wear resistance.

The invention discloses a preparation method of carbide-enhanced Ni / Cr composite binding phase Cr3C2-based metal ceramic, and belongs to the field of composite materials. The preparation method is characterized by comprising the following steps: firstly, respectively weighing 0 to 25 weight percent of binder metal powder, 0 to 16 weight percent of second-phase carbide powder, 0 to 1 weight percent of carbon supplementing agent carbon powder and the balance of chromium carbide (Cr3C2) powder; the carbide-enhanced Ni / Cr composite binding phase Cr3C2-based metal ceramic is prepared through traditional powder metallurgy processes such as chromium carbide-second phase carbide pre-ball-milling, mixed material ball-milling, ball-material separation, drying and sieving, glue mixing and granulation, compression molding, vacuum pressureless sintering and the like. The Ni / Cr composite metal powder is used as a binder, the second-phase carbide is used as a modifier, and the carbon powder is used as a carbon supplement agent, so that the problems that the market price of binder metal nickel is relatively high, domestic mineral resources are scarce, a decarburization phase is easily generated in the sintering process of Cr3C2 in industrial production, grains grow abnormally and the like are solved; on the basis of ensuring the wear resistance and corrosion resistance of the chromium carbide-based metal ceramic, certain hardness is improved, and the chromium carbide-based metal ceramic is suitable for the fields of cutting tools, wear-resistant and corrosion-resistant parts and the like.

The invention relates to a lithium fluoride ceramic target material and a preparation method and application thereof, and the preparation method comprises the following steps: uniformly mixing lithium fluoride and a binder solution to obtain a precursor, carrying out mold pressing or dry pressing molding on the precursor, and then carrying out cold isostatic pressing molding to obtain a biscuit; carrying out pressureless sintering on the biscuit to obtain a sintered body, and carrying out HIP post-treatment on the sintered body to obtain a lithium fluoride ceramic target material; according to the method, under the condition that no sintering aid is introduced, the defects such as pores in the grain boundary area of the sintered body are removed by adding the HIP post-treatment process, and the lithium fluoride ceramic target material with relatively high density is obtained. The high-density lithium fluoride ceramic target material can be obtained by adopting a mode of combining pressureless sintering and HIP post-treatment, and the density of the lithium fluoride ceramic target material prepared by the method is 97%-99%.

The invention provides a preparation method of a carbon fiber reinforced boron carbide composite material, and belongs to the technical field of boron carbide composites.The preparation method comprises the steps that S1, 88-92 parts by weight of boron carbide powder and 5-7 parts by weight of modified graphene nanosheets are mixed, subjected to wet ball milling treatment, filtered and dried, and primary powder is obtained; the modified graphene nanosheet is prepared by modifying a graphene nanosheet with a silane coupling agent; s2, uniformly mixing the primary powder obtained in the step S1 with 8-10 parts of porous carbon fibers to obtain final powder, and granulating and sieving the final powder by using a binder to obtain mixed granules; and S3, pouring the mixed granules obtained in the S2 into a mold, maintaining the pressure for 5-8 minutes under 280-300 MPa, releasing the pressure, stripping from the mold, keeping the temperature at 2100-2300 DEG C for 1.5-2 hours, carrying out vacuum pressureless sintering, and cooling to room temperature along with a furnace to obtain the carbon fiber reinforced boron carbide composite material. The toughness of the prepared composite material can be enhanced, and meanwhile, the thermal conductivity of the composite material is improved.

The invention relates to a method for preparing pressureless sintered silicon carbide ceramics through gel injection molding, and relates to the technical field of ceramics, the method comprises the following steps: adding an organic phase into water, stirring and dissolving to obtain an organic phase solution, adding a cross-linking agent, a dispersing agent, a defoaming agent and a suspending agent into the organic phase solution, and stirring to obtain a premixed solution; adding the powder into the premixed liquid, and stirring to obtain slurry; carrying out ball milling treatment on the slurry, carrying out defoaming treatment after ball milling, and carrying out vibration treatment during defoaming, so as to obtain defoamed slurry; adding a catalyst and an initiator into the defoamed slurry, stirring, pouring into a mold, forming to obtain a green body, drying the green body according to a drying system to obtain a dried green body, and performing pressureless sintering on the dried green body to obtain a silicon carbide ceramic product. The silicon carbide ceramic has the effects of improving the density, hardness and drying performance of the silicon carbide ceramic, the strength of a green body can be effectively improved, and the phenomena of cracking and deformation are reduced.

The invention relates to the technical field of preparation of silicon carbide materials, in particular to a preparation method of high-density recrystallized silicon carbide, which comprises the following steps: 1) putting silicon carbide powder with different particle sizes, an additive and a solvent into a mixer, and fully and uniformly mixing to obtain pug for preparing the high-density recrystallized silicon carbide; the additives comprise a plasticizer, a binder, a pH regulator and a sintering aid; (2) pug is put into a kneading and extruding all-in-one machine to be subjected to pugging and forming; 3) drying the formed pug to obtain a dry blank for preparing high-density recrystallized silicon carbide; and 4) putting the dry blank into a recrystallization sintering furnace, and carrying out high-temperature sintering according to a sintering curve and a sintering atmosphere to obtain a high-density recrystallized silicon carbide product. Through optimized process parameters and an innovative preparation process, a pressureless sintering process is coupled in a recrystallization process, so that the density and the crystallization quality of the silicon carbide material are remarkably improved.

The invention discloses a method for preparing high-transparency yttrium iron garnet ceramic by combining a chemical synthesis way with pressureless sintering. The method comprises the following steps: synthesizing submicron alpha-iron oxide powder; forming the powder; and carrying out pressureless sintering in an oxygen atmosphere. The YIG transparent ceramic prepared in the invention has very high transmittance (the highest transmittance is 40% at 1.5 m) in an infrared band, and the YIG transparent ceramic with high optical quality (the transmittance is as high as 75% at 1.5 m) can be obtained by combining oxygen hot isostatic pressing sintering. And the preparation process is simple, the synthesis conditions are easy to control, the material synthesis period is short, energy and cost are saved, and the requirements of industrial production are met.

The application discloses a ZTA ceramic particle preform, preparation and application of realizing metallurgical interface combination between ZTA and high manganese steel matrix. The application adopts a ball milling process to prepare a slurry from high manganese steel powder, Zr-Fe powder, ZTA micro powder and ethanol, soaks ZTA particles in the slurry, takes out and dries and sinter, obtains ZTA particles with a single layer of coating, soaks the ZTA particles in high manganese steel powder slurry again, obtains ZTA particles with two layers of coating, obtains ZTA ceramic preform through pressureless sintering, realizes solidification of the double coating layers, and the ZTA ceramic porous preform can effectively promote high manganese steel melt infiltration and prevent the preform from collapsing under thermal shock during casting. Through the bridge effect of the FeZr-ZTA-high manganese steel powder double coating layers, a metallurgical combination interface is formed between the ZTA and the high manganese steel matrix, so that the prepared ZTA ceramic particle reinforced high manganese steel composite material has excellent three-body wear resistance.

The invention relates to a method for improving low-temperature aging resistance of zirconia ceramic by utilizing defect engineering, which comprises the following steps: S1, preparation of zirconia slurry: taking zirconia powder with 3 mol% of yttrium oxide as a stabilizer as a raw material, and weighing the zirconia powder and deionized water according to a mass ratio of (1.5-2.5): 1; citric acid or acetic acid or nitric acid is dropwise added into deionized water, and the pH is adjusted to be 2.5-4; adding zirconium oxide powder into the adjusted aqueous solution step by step, and stirring to obtain zirconium oxide slurry; s2, introduction of powder intragranular defects: pouring the zirconium oxide slurry obtained in the step S1 into a sand mill, carrying out sanding treatment for 8-12 hours by adopting zirconium oxide microbeads as a medium, and introducing blade dislocation and lattice distortion crystal defects into zirconium oxide powder crystals; s3, after the powder containing the intragranular defects obtained in the step S2 is formed, pressureless sintering is conducted at the temperature of 1350-1425 DEG C in the air atmosphere, and the compact 3Y-TZP zirconia ceramic containing the intragranular defects is obtained. The phase transformation of the zirconia ceramic from a tetragonal phase to a monoclinic phase can be effectively inhibited, and the low-temperature aging resistance of the zirconia ceramic is improved.

The invention provides a MoAlB-SiC composite material as well as a preparation method and application thereof, and belongs to the technical field of ceramic matrix composite materials. The preparation method of the composite material comprises the following steps: mixing Mo powder, Al powder and B powder according to a molar ratio of 1: (1-2): 1, carrying out wet ball milling, drying, and carrying out vacuum pressureless sintering to obtain MoAlB powder; and S2, adding SiC particles with the mass percentage of 5%-20% into the MoAlB powder obtained in the step S1, carrying out wet ball milling, drying, and carrying out electric field assisted direct current heating rapid hot pressed sintering to obtain the MoAlB-SiC composite material. The MoAlB-SiC composite material obtained through the preparation method is high in density, secondary phases are reduced, the mechanical performance and the high-temperature oxidation resistance of the MoAlB material are enhanced by adding SiC, and the preparation method has great significance for preparing the high-strength MoAlB-based ceramic composite material.

The invention discloses a construction method and application of a gradient metallurgical composite interface between ZTA ceramic particles and an alloy steel matrix. The preparation method comprises the following steps: firstly, preparing Zr-Fe alloy powder and ZTA micro powder into slurry by using ethanol, coating the surfaces of ZTA particles with the slurry, and pre-sintering to obtain ZTA particles with Zr-Fe-ZTA coating layers; the preparation method comprises the following steps: preparing a Zr-Fe-ZTA coating layer, soaking the ZTA particles with the Zr-Fe-ZTA coating layer in slurry prepared from Zr-Fe alloy powder, alloy steel powder and ethanol to realize secondary coating on the surfaces of the ZTA particles, and finally performing pressureless sintering to prepare the ZTA ceramic preform. Due to the bridge action of double-layer coating of the Zr-Fe-ZTA and the Zr-Fe-alloy steel powder, a metallurgical bonding interface is formed between ZTA ceramic and alloy steel, so that the impact abrasive wear resistance of the ZTA ceramic particle reinforced alloy steel composite material is greatly improved, and the ZTA ceramic particle reinforced alloy steel composite material can be applied to preparation and production of the ZTA ceramic particle reinforced alloy steel composite material.

Provided are an oxide sintered body mainly containing a molybdenum oxide, a sputtering target containing the sintered body, and an oxide thin film formed by the sintered body. In the present invention, by adding a specific (pseudo) metal oxide in a prescribed range to a molybdenum oxide and a niobium oxide which are difficult to sinter, the sinterability can be improved and high-density characteristics can be ensured even if pressureless sintering is performed.

The present invention discloses an in-situ pressureless sintering method for preparing a TiB2 / MgAl2O4 composite ceramic material, relating to the technical field of special ceramics. The method comprises the following steps: S1, ball-milling TiO2, B4C, MgO, Al2O3, and LiF, drying, and sieving to obtain a powder; S2, adding a binder to the powder for granulation; S3, press-molding the granulated powder; and S4, calcining the molded material at 1600-1700°C for 50-90 minutes, followed by holding at 500-600°C for 1-2 hours. The TiB2 / MgAl2O4 composite ceramic material is prepared using a one-step in-situ method. The composite ceramic material has a uniform microstructure, a strong reaction driving force, a simplified process, and a compact flow. It also exhibits excellent dielectric properties and can be used to manufacture absorbing materials, reducing electromagnetic wave reflection and improving stealth performance. Furthermore, the one-step in-situ reaction process produces abundant heterogeneous interfaces on a microscale, effectively improving the material's polarization loss performance.

The application relates to a dual-phase mosaic middle-entropy oxide anti-ablation ceramic and a preparation method thereof, and belongs to the technical field of ceramic materials. The method comprises the following steps: firstly, high-temperature heat treatment is adopted to prepare dual-phase middle-entropy oxide ceramic powders ((Hf, Zr, Ti)O2 and (Hf, Zr)TiO4) with different proportions; and then, a composite-phase mosaic structure ceramic is prepared by means of pressureless sintering. The method not only provides a theoretical basis for optimal anti-cyclic ablation performance component design of Hf-Zr-Ti-based multicomponent ultrahigh-temperature ceramic, but also lays a material foundation for the application of the prepared ceramic powder in substrate modification and coating preparation in the future. In addition, the pressureless sintering preparation of the dual-phase mosaic middle-entropy oxide anti-ablation ceramic block can realize low-cost and large-scale production. The process can not only realize low-cost and large-scale production, but also obtain uniformly distributed dual-phase middle-entropy oxides, fully exert the mutual synergistic effect among multicomponent oxides, and simultaneously improve the resistance to cyclic thermal shock and the anti-ablation performance of the ceramic block.

The application provides a low-temperature sintering silicon nitride ceramic powder, a silicon nitride ceramic and a preparation method thereof, and uses beta silicon nitride powder as raw material and low-melting-point glass powder as a sintering aid. The beta silicon nitride powder with a content of 75-90wt% and a particle size range of 0.5-1um is selected, and the low-melting-point glass powder with a content of 10-25wt% is added. The mixed powder is ball milled, dried and pressed into a sheet, and then cold isostatic pressing is carried out, and pressureless sintering is carried out at 1400-1600 DEG C under a nitrogen atmosphere to obtain a silicon nitride ceramic material. The beta silicon nitride powder provided by the application can directly sinter the beta silicon nitride ceramic at low temperature. The preparation method of the silicon nitride ceramic provided by the application reduces the sintering temperature of the silicon nitride, improves the preparation efficiency of the silicon nitride ceramic, and is mainly applied to refractory fire-resistant materials.