222 results about "Relative density" patented technology

The invention discloses a preparation method of low-temperature rapid densification silicon nitride ceramic based on an aluminum oxide-yttrium oxide composite sintering aid, and aims to solve the problems of high temperature, high energy consumption, difficult densification and the like in the existing Si3N4 ceramic preparation. The preparation method comprises the following steps: 1, mixing alpha-Si3N4 powder, Y2O3 powder and Al2O3 powder, and carrying out ball milling dispersion to obtain mixed powder; 2, carrying out rotary evaporation drying on the mixed powder under a vacuum condition; 3, carrying out heat preservation treatment under the conditions of 1600-1700 DEG C and 40-60 MPa through a spark plasma sintering process; and 4, demolding after cooling. Under the action of the Al2O3-Y2O3 composite sintering aid, phase transformation from alpha-Si3N4 to beta-Si3N4 is remarkably promoted, the relative density of the ceramic reaches 97%-99%, the fracture toughness of the ceramic is 5.21 MPa.m < 1 / 2 >, and the bending strength of the ceramic is 924.99 MPa.

The invention provides a method for preparing a high-performance silicon nitride ceramic ball based on a pressure modulation sintering technology, and relates to the field of functional ceramic material preparation, and the method comprises the following steps: 1, preparing a green body; 2, PMS sintering is carried out; step 3, cooling; traditional high-performance silicon nitride ceramic balls (the relative density is required to be larger than 99%, the Vickers hardness is required to be larger than or equal to 1500 kgf / mm, the bending strength is required to be larger than or equal to 920 MPa, and the fracture toughness is required to be larger than or equal to 6.0 MPa.m / ) are mainly prepared through a two-step process of normal pressure / air pressure sintering (GPS) and hot isostatic pressing (HIP). Although high densification of the material can be realized, the method has the problems of complicated process flow, high energy consumption, long production period, high equipment occupancy rate and the like.

The invention provides an iron yoke structure design method based on a variable density method, and is applied to the field of superconducting electrical iron yoke design. The method comprises the following steps: establishing a target equipment two-dimensional model comprising a superconducting coil, a workpiece and an iron yoke, and setting coil excitation, material attributes and electromagnetic boundary conditions; defining an iron yoke design space and dividing finite elements, and taking the relative density of the finite elements as a design variable; establishing a topological optimization model by taking the magnetic pole gap magnetic flux density as a target function and the yoke volume as a constraint; carrying out magnetic field finite element analysis by utilizing a material attribute interpolation model to obtain magnetic field distribution, and then calculating a magnetic pole gap magnetic flux density module value integral to obtain a target function value; solving the sensitivity of the target and the constraint function to the design variable, modifying the sensitivity, inputting a gradient optimization algorithm, and updating the design variable under the condition that the constraint is satisfied; and if the target function change is smaller than the convergence tolerance, outputting the yoke structure. The invention further provides an iron yoke structure, a device, equipment, a medium and a program product.

The present invention relates to a preparation process of a high-density tungsten-copper alloy. The preparation process comprises: mixing oxide powder of copper having a certain proportion with oxide powder of tungsten in a dual-power mixer, performing crushing and activation treatment on the mixed powder in a high-speed crusher, and then reducing in a hydrogen atmosphere to obtain the nano tungsten-copper composite powder; and carrying out sheathing, degassing, and hot isostatic pressing treatment on the nano tungsten-copper composite powder, carrying out thermoplastic processing, and then carrying out annealing treatment to obtain the high-density tungsten-copper alloy. The process of the present invention is simple and controllable, has high operability, and is easy to industrialize; the phenomena of component segregation caused by preparation of the tungsten-copper alloy by an infiltration method, and uneven crystal grain size caused by particle aggregation and growth are avoided; and the proportion of the two-phase components can be accurately regulated, so that the tungsten-copper alloy with a tungsten content of 5%-95% can be prepared. The density (relative density) of the prepared tungsten-copper alloy reaches 99.6% or above; the oxygen content is lower than 40 ppm; the alloy has a uniform structure; the crystal grains are fine; and the present invention has wide application prospects and popularization value.

The invention discloses a sintering model construction method and system for ceramic material densification parameter prediction, and relates to the technical field of material science. The method comprises the following steps: quantitatively describing a deformation mechanism of a ceramic material in a sintering process based on continuum mechanics; constructing a sintering model according to the quantitatively described deformation mechanism and densification mechanism of the ceramic material; densification parameters in the sintering process are determined, and the optimal densification parameters are predicted through the sintering model; and calculating the relationship between the instantaneous relative density and the height change of the pressed blank, and verifying the prediction result of the sintering model according to the relationship between the instantaneous relative density and the height change of the pressed blank. According to the method, the macroscopic densification rate and the relative density in the sintering process can be accurately simulated and predicted by constructing the sintering model.

The present disclosure addresses the problem of providing: a high-density V2O3 sintered compact; a method for producing a high-density V2O3 sintered compact; and a high-density V2O3 sputtering target. The V2O3 sintered compact has a relative density of 95% or more. The method for producing a V2O3 sintered compact comprises subjecting a V2O3 powder to hot press sintering at 1350-1450°C under vacuum or in an inert atmosphere gas.

Provided is a sputtering member composed of an alloy of Co and a group 5 element in the periodic table, such as a Co-Nb alloy, capable of suppressing particles generated during sputtering. This sputtering member contains not less than 1 at% but less than 25 at% of Nb, the remaining portion being Co and unavoidable impurities. The sputtering member has a relative density of 99.7% or more. This sputtering member contains not less than 1 at% but less than 25 at% of the total of one or more of V, Nb, and Ta, the remaining portion being Co and unavoidable impurities. The sputtering member has a relative density of 99.7% or more.

The invention belongs to the technical field of refractory materials. The invention provides a graphene ceramic composite material and a preparation method and application thereof, the preparation method comprises the following steps: adding zirconium boride particles, silicon carbide particles, yttrium oxide and lanthanum-doped cerium oxide into a graphene oxide dispersion liquid, and carrying out ball milling and drying to obtain raw material powder; the raw material powder is put into a graphite mold to be sintered, and the graphene ceramic composite material is obtained. The raw material powder is prepared from the following components in parts by volume: 5.6 to 6 parts of graphene oxide, 70 to 72 parts of zirconium boride particles, 20 to 21 parts of silicon carbide particles, 1.5 to 2 parts of yttrium oxide and 1 to 1.3 parts of lanthanum-doped cerium oxide. By increasing the content of graphene oxide, the bending strength of the composite material is further improved while the relative density of the prepared composite material is increased.

The invention relates to the technical field of powder metallurgy, in particular to an AlNbB alloy target material and a preparation method thereof. The preparation method comprises the steps of pre-sintering, degassing and hot isostatic pressing. In the pre-sintering step, mixed powder composed of Al powder, Nb powder and B powder is placed in a mold, and spark plasma pre-sintering is conducted; the sintering temperature ranges from 350 DEG C to 450 DEG C, the applied pressure ranges from 15 MPa to 25 MPa, and the temperature and pressure maintaining time ranges from 10 min to 20 min; and in the hot isostatic pressing step, the degassed ingot blank is subjected to hot isostatic pressing, the hot isostatic pressing temperature ranges from 450 DEG C to 550 DEG C, the pressure ranges from 120 MPa to 170 MPa, and the heat preservation and pressure maintaining time ranges from 3 h to 6 h. The relative density of the AlNbB alloy target material prepared through the preparation method is 98% or above, and the AlNbB alloy target material is compact in structure, uniform in element distribution, free of segregation and high in product percent of pass.

The invention discloses a preparation method of a high-strength and high-toughness 17-4ph material. The preparation method comprises the steps of powder treatment, mixing, injection molding, degreasing, sintering and heat treatment. The preparation method comprises the following steps: pretreating fine powder in nitrogen to obtain nitrogen-containing fine powder, mixing the nitrogen-containing fine powder with coarse powder, then carrying out mixing, injection molding and degreasing, and finally carrying out high-temperature sintering and solid solution aging treatment in a nitrogen atmosphere. The prepared 17-4ph material has the excellent comprehensive performance that the relative density is larger than or equal to 97%, the hardness is larger than or equal to 40 Hrc, the tensile strength is larger than or equal to 1200 MPa, the yield strength is larger than or equal to 1000 MPa, and the ductility is larger than or equal to 20%, and the 17-4ph material is suitable for being applied to high-end medical instruments such as surgical robots.

Disclosed is a Cr-Si-C sintered body having a high density, and at least one of a Cr-Si-C sintered body having a high density, a sputtering target including the same, and a method for manufacturing a film using the sintered body. According to the present application, a Cr-Si-C sintered body having a relative density of 90% or more and a porosity of 13% or less can be provided.

The application provides a method for preparing dense aluminum phosphate ceramics at low temperature and fast speed, and the steps are as follows: aluminum phosphate powder and 3-6wt.% of sintering aid yttrium oxide powder are weighed respectively, dry mixing is carried out by using an acoustic resonance mixing instrument, and uniform mixing is carried out to obtain primary mixed powder; the obtained primary mixed powder is sieved through a 200-mesh screen to obtain mixed powder; the mixed powder is loaded into a graphite mold and then placed in a discharge plasma sintering furnace for sintering to obtain dense aluminum phosphate ceramics. The application solves the problem of difficult sintering of aluminum phosphate ceramics by adding a small amount of sintering aid, and realizes low-temperature and fast densification of aluminum phosphate ceramics in combination with the discharge plasma sintering technology. The relative density of the prepared dense aluminum phosphate ceramics can reach 97%.

The application relates to the technical field of tungsten-rhenium alloy, and discloses a tungsten-rhenium alloy stir head material for friction stir welding, which is characterized in that the tungsten-rhenium alloy stir head material is prepared by reducing and sintering tungsten-rhenium precursors, the tungsten-rhenium precursors are prepared by using ammonium metatungstate, ammonium rhenate and oxalic acid as raw materials, and the application further discloses a preparation method of the tungsten-rhenium alloy stir head material, which comprises the following steps: S1, tungsten-rhenium precursor preparation: after ammonium metatungstate, ammonium rhenate and oxalic acid are dissolved, stirred and heated to react, spray drying is carried out to obtain tungsten-rhenium precursor powder; and S2, tungsten-rhenium precursor powder reduction: tungsten-rhenium precursor powder is heated and reduced in a hydrogen environment to obtain tungsten-rhenium alloy powder. The preparation process is simple, fast, low in cost and convenient for batch industrial production; the prepared single-phase tungsten-rhenium alloy is high in hardness and density and uniform in composition; the relative density of the tungsten-rhenium alloy after sintering reaches 99.6%, the microhardness value is 585+ / -5 Hv, and the grain size is 1-2 mu m.

The application discloses a carburized nanoscale yttrium oxide shell and a preparation method thereof. The preparation method comprises the following steps: preparing a nanoscale yttrium oxide shell embryo by using a grouting method; and placing the shell embryo after high-temperature sintering in a vacuum induction melting furnace filled with high-concentration active carbon to perform carburization treatment. The nanoscale yttrium oxide shell treated by using the carburization technology has excellent high-temperature resistance and chemical inertness, can reduce the pollution of yttrium oxide particles to a TiAl alloy melt, hinder the occurrence of a TiAl alloy melt-shell interface reaction, and make the surface of the TiAl alloy after melting more smooth, so that columnar grains on the surface of an alloy ingot can be clearly observed. Moreover, the shell has high bending strength and Vickers hardness, and the relative density is increased, so that the problem of the cracking of the yttrium oxide shell after the melting of the TiAl alloy is solved. The bending strength of the yttrium oxide shell prepared by the application can reach 24.3 MPa, and the Vickers hardness can reach 152 HV.

The application discloses a method for preparing large-size rare earth barium copper oxygen superconducting target material and relates to the technical field of superconducting target material preparation. The method realizes the compatibility of a single set of molds with various specifications of target materials by optimizing the design of cold isostatic pressing molds, adopting a composite mold structure comprising upper and lower cover plates, a cylinder, isolation pads, a replaceable elastic lining and a clamp, and can press multiple target materials at a time by setting multiple isolation pads, and is suitable for the preparation of target materials with a diameter of 8-12 inches and a thickness of 10-20 mm. The preparation process comprises the following steps of mold assembly, superconducting powder filling and vibration treatment, segmented pressure cold isostatic pressing treatment, blank shaping, oxygen atmosphere sintering and grinding machine processing. The mold generality design and batch pressing technology of the application significantly improve the production efficiency, reduce the mold cost and powder loss, and at the same time, ensure the density (relative density 80%-85%) and surface flatness (less than or equal to 0.5 mm) of the target material, and meet the strict requirements of large-size target materials for high-end superconducting thin film preparation such as pulsed laser deposition.

This invention belongs to the field of silicon nitride ceramic technology, specifically relating to a TEOS-coated silicon nitride ceramic powder, its preparation method, and its application. The TEOS-coated silicon nitride ceramic powder comprises a core layer and a coating layer; the core layer comprises silicon nitride; the coating layer is mainly prepared from tetraethoxysilane; based on the mass of SiO2, the mass of the coating layer is 0.5–15 wt% of the mass of the core layer. The TEOS-coated silicon nitride ceramic powder prepared by this invention can achieve a better refractive index match with photosensitive resin and a more uniform interface in photocurable ceramic forming processes, reducing light scattering and absorption unevenness problems, and significantly increasing the curing depth under the same exposure conditions. When used as a sintering aid, the TEOS-coated silicon nitride ceramic powder prepared by this invention can lower the densification temperature of silicon nitride ceramics while improving relative density and mechanical properties.

This application provides a filler for an encapsulation material and its preparation method, a magnetic molding compound, and an encapsulation device. The filler for the encapsulation material includes ferrite particles, wherein the ferrite particles include nickel-copper-zinc ferrite (Ni... a Zn b Cu c Fe d The O4 material has the following properties: a ranges from 0.3 to 0.55, b ranges from 0.45 to 0.55, c ranges from 0 to 0.2, and d ranges from 1.8 to 2. The ferrite particles have a particle size of 2-11 μm, accounting for 50-70% of the total. This filler has advantages such as low relative density, wide absorption bandwidth, and good high and low temperature performance, thereby reducing the overall weight of the packaged device and improving its electromagnetic interference resistance and applicable temperature range.

The invention discloses a preparation method of a nitrogen-reinforced high-hardness corrosion-resistant 17-4ph material. The preparation method comprises the steps of mixing, injection molding, degreasing, nitrogen sintering and heat treatment. Through in-situ nitrogen solid solution strengthening, a strengthened martensite matrix structure is obtained. The relative density of the obtained material is larger than or equal to 97%, the Hrc hardness is larger than or equal to 46, the tensile strength is larger than or equal to 1500 MPa, the yield strength is larger than or equal to 1200 MPa, the ductility is larger than or equal to 5%, the neutral salt spray test corrosion resistance time is larger than or equal to 48 h, and the material is suitable for surgical robots and other high-end medical instruments.

The invention relates to a lattice structure performance characterization and optimization design method based on laser powder bed melting, and belongs to the technical field of additive manufacturing and structural design. The method aims at improving the mechanical property of a traditional BCC lattice structure under complex loads. The equivalent Young modulus of the lattice structure can be effectively represented by providing a lattice performance characterization method based on large unit cell hypothesis and establishing an analytic relationship between the equivalent Young modulus and the relative density of the lattice. In addition, topological optimization design of the BCC dot matrix is carried out by adopting an SIMP method, and redundant struts are removed and the structural shape is optimized by taking maximization of the equivalent Young modulus of the dot matrix as an optimization target. Finally, compared with a traditional BCC dot matrix, the T-BCC dot matrix structure manufactured through the LPBF process shows higher rigidity and strength. According to the optimization design method, the compression resistance of the lattice structure can be improved on the premise that the light weight of the lattice structure is kept, and the method has wide application prospects in the field of high-end equipment such as aerospace and automobiles.

The invention discloses a rare earth AB2 type hydrogen storage alloy and a preparation method thereof, and relates to the field of hydrogen storage alloys, and the rare earth AB2 type hydrogen storage alloy comprises the following components in percentage by mass: 50% of titanium, 45% of manganese, 2.5-3.5% of lanthanum and 1.5-2.5% of cerium. By adjusting the adding proportion of rare earth elements, the lattice stress of the alloy is optimized, the hydrogen storage performance is improved, and the raw material cost is reduced; a proper amount of additive is added to improve the performance of the alloy; in the preparation process, the processes of crushing and ball-milling after raw material sintering are added, the alloy particle granularity is refined, the hardness and relative density of the alloy are improved, and the service life is prolonged.

A preparation method of high-density low-indium-content ITO target material, comprising the following steps: (1) mixing indium oxide and tin oxide micro-nano powder according to the indium content, then adding sintering aid antimony trioxide, uniformly mixing and grinding, and forming a green body; (2) after the green body is degreased, sintering is performed to obtain the ITO target material with high density (relative density >= 99.5%), low resistivity (<= 1*10 ‑3 Ω*cm) and low indium content (40.5-42%). The indium content is further reduced and the resistivity is reduced by tin doping on the In4Sn3O2 material. The relative density of the target material is improved by adding a suitable proportion of sintering aid and sintering at high temperature for a short time.

This invention discloses a method for simulating and testing ceramic sintering stress and a method for reducing ceramic sintering stress. The simulation and testing method includes: 1. Measuring the grain size, relative density, and geometric dimensions before and after sintering; 2. Using Abaqus to establish the ceramic geometry and construct a transient heat conduction model; 3. Establishing the viscoelastic constitutive equation for the sintering shrinkage deformation of zirconia ceramics and constructing a sintering shrinkage model; 4. Sequentially coupling the transient heat conduction model and the sintering shrinkage model to perform joint simulation of solid-state sintering, obtaining the simulation results of ceramic sintering stress. The method for reducing ceramic sintering stress includes: 5. Establishing a finite element model of ceramic sintering shrinkage with proportionally distributed grain sizes and calculating the average sintering stress distribution of the grain size proportional distribution model; 6. Comparing the average sintering stress of sintering shrinkage models with different grain size proportions to determine the method for reducing sintering stress. This invention improves ceramic sintering quality and production efficiency.

This invention discloses a two-step oscillating hot-pressing sintering method for WC-Co cemented carbide. Specifically, the method involves: loading WC-Co cemented carbide mixed powder into a mold and pre-pressing it; firstly, holding the powder at 800°C in a vacuum environment to degas and pre-sinter the billet; then applying unidirectional oscillating pressure to the billet through the mold and raising the temperature to 1100°C for solid-state sintering. Dynamic pressure causes WC particles to rearrange, and Co particles undergo severe plastic deformation under the pressure of the WC particles, further increasing the relative density of the billet; finally, the temperature is raised to 1300-1350°C to form a WC-Co eutectic liquid phase. Dynamic pressure drives further particle rearrangement, and the eutectic liquid phase uniformly fills the gaps between WC particles, completing the sintering process. This invention improves the three-dimensional spatial distribution uniformity of the Co phase, eliminates residual porosity, effectively inhibits abnormal growth of WC grains, and produces cemented carbide with excellent strength and toughness.

The application relates to a preparation method of a low-oxygen heterogeneous structure tungsten-based composite material, and relates to the technical field of tungsten-based composite material preparation. W powder, Ti powder, TiB2 powder and WC hard alloy balls are loaded into a ball mill tank for ball milling; then a two-step sintering method is adopted to prepare W-Ti-TiB2 tungsten-based composite material with high hardness and low oxygen content. The relative density of the prepared W-Ti-TiB2 tungsten-based composite material reaches 92.0% or more, and the microhardness value is 425-530 HV, which is superior to that of pure tungsten material (microhardness 360-420 HV). The oxygen content (20-80 ppm) of the prepared new heterogeneous structure W-Ti-TiB2 tungsten-based composite material is lower than that of pure tungsten (70-180 ppm) prepared by the same process and W-Ti-TiB2 tungsten-based composite material (150-380 ppm) prepared by the same process but with different powder loading sequences.

The invention belongs to the technical field of ceramic material preparation, and discloses a ceramic material sintering process optimization method and system based on a grain growth dynamic model, and the method comprises the following steps: quantitatively describing a deformation mechanism of a ceramic material in a sintering process based on continuum mechanics; constructing a grain growth kinetic model according to the quantitatively described deformation mechanism of the ceramic material and the grain size estimation model at the final stage of sintering; determining grain growth parameters in the final stage of sintering, and predicting the grain size by using a grain growth kinetic model; calculating the relationship between the grain size and the relative density and the sintering temperature, and verifying the calculation result of the grain growth kinetic model according to the experimental result of the grain size and the relative density; the change from low temperature to high temperature behavior is simulated through a Sigmodal function, the slope (derivative) of the function is calculated, and the temperature transition point of grain growth is obtained. And the temperature transition point of the grain boundary mobility from high to low can be accurately determined.

The invention discloses a preparation method of a high-tensile-strength and high-extensibility yttrium oxide particle reinforced tantalum-based composite material, and belongs to the field of refractory metal-based composite materials. The yttrium oxide particles are added, so that abnormal growth of tantalum grains in the powder metallurgy process can be effectively inhibited, and the grain size of the tantalum-based composite material is regulated and controlled. The engineering stress and deformation capacity of the tantalum-based composite material are remarkably improved in the high-temperature service process of the yttrium oxide particle reinforced tantalum-based composite material. According to the method, the content of yttrium oxide with different volume fractions can be accurately regulated and controlled in a large range. The yttrium oxide particle reinforced tantalum-based composite material prepared by the method has the advantages of fine crystal grains, inhibition of abnormal growth of the crystal grains, high engineering stress and high deformation elongation. The relative density gt of the yttrium oxide particle reinforced tantalum-based composite material; the tensile strength of the alloy is 100-650 MPa, the elongation is 98%, the room-temperature hardness is 1.6-2.1 GPa, the tensile strength is 100-650 MPa, and the ductility is 2%-27%.

The invention discloses a method for preparing silver-tungsten-nickel graphite through an infiltration method. The preparation method specifically comprises the steps that S1, raw materials are prepared and mixed, and mixed raw material powder and nickel graphite powder are mixed; s2, the mixed powder is subjected to pressing, dewaxing sintering and sintering infiltration, and a product is formed; s3, cleaning and drying the product; the nickel is added into the silver-tungsten graphite, the silver-tungsten-nickel graphite powder raw material is mixed and granulated, and dewaxing, sintering and infiltration are performed in the protective atmosphere, so that the wettability problem of liquid silver and solid substances at the infiltration temperature, particularly the wettability problem of silver and graphite, is solved, and the sintering and infiltration can be smoothly completed; the relative density of the prepared AgWNi / C reaches 97% or above, the electric conductivity IACS% can be improved by about 5%-40%, the tensile strength is improved by 80 Mpa-300 Mpa, and the use amount of AgW / C electric contact silver is reduced by 5%-50%.

This invention discloses a beryllium-titanium alloy microsphere for neutron multiplication materials and its preparation method, belonging to the field of beryllium-titanium alloy technology. The preparation method includes: Step S1, ball milling and mixing beryllium powder and titanium powder at a predetermined mass ratio, followed by a first dry particle composite process to obtain beryllium-titanium spherical powder. Step S2, adding a polyvinyl alcohol binder to the beryllium-titanium spherical powder, followed by a second dry particle composite process to obtain beryllium-titanium granulated powder. Step S3, filling the beryllium-titanium granulated powder into multiple flexible spherical molds, then placing the multiple flexible spherical molds into a sleeve and performing cold isostatic pressing to obtain beryllium-titanium powder blank microspheres. Step S4, degreasing the beryllium-titanium powder blank microspheres under inert gas protection. Step S5, sintering the degreased beryllium-titanium powder blank microspheres to obtain beryllium-titanium alloy microspheres with a diameter of not less than 5 mm and a relative density ≥ 98%.

The invention relates to the technical field of powder metallurgy, and discloses metal powder vacuum hot pressing sintering forming equipment which comprises a relative density processing module, a feedforward prediction evaluation module, a state feedback evaluation module, a signal credibility evaluation module and a dwell pressure regulation and control module. The relative density, the sintering temperature, the upper pressure head displacement, the mold-powder system temperature difference, the vacuum degree and the hydraulic system oil temperature are monitored in real time, the densification driving force index, the relative density index, the pressure trend factor, the system rigidity factor and the signal credibility are calculated respectively, and the target dwell pressure is dynamically adjusted based on the densification driving force index, the relative density index, the pressure trend factor, the system rigidity factor and the signal credibility. According to the equipment, self-adaptive adjustment of pressure maintaining pressure in the sintering process is achieved, the problems of traditional control lag and pressure fluctuation are effectively solved, and the product density and quality consistency are improved.