206results about How to "High degree of densification" patented technology

Annular substrates (20) are stacked in an enclosure where they define an inside volume (24) and an outer volume (26) outside the stack. A gas containing at least one precursor of a matrix material to be deposited within the pores of the substrates is channeled inside the enclosure to a first one (24) of the two volumes, and a residual gas is extracted from the enclosure from the other one (26) of the volumes. One or more leakage passages (22) allow the volumes to communicate with each other, other than through the substrates. The total section of the leakage passages has a value lying between a minimum value for ensuring that a maximum gas pressure in the first volume is not exceeded until the end of densification, and a maximum value such that a pressure difference is indeed established between the two volumes from the beginning of densification.

A copper base alloy, which possesses high-strength, high conductivity, oxidation resistance and contains silver of low content, is characterized in that said high-strength high-conductivity oxidation-resistance low-silver copper base alloy is composed of low-silver copper base alloy powder, diamond powder of 0.2-1.0% and graphitized nanometer carbon fibre and is prepared through a powder metallurgy technological process, wherein said low-silver copper base alloy powder contains Ag of 0.08 -0.12%, Y, La and Ce of 0.05 -0.5% or one of misch metal or mixture of several misch metal. Said alloy in accordance with the present invention possesses higher intensity and hardness, stronger anti-crackle forming and stomatic expandability, and exhibits definite puddle welding resistance and better electroconductive performances at the same time.

The invention discloses a composite shielding material and a preparation method thereof and aims at solving the problems that when a B4C/Al composite material is used as a shielding material and the content of B4C exceeds a certain percentage, bad mechanical performance, plastically and workability of the material bring great difficulty for preparation of the material to greatly affect the application of the material although the higher the content of the B4C is, the greater and better the shielding effect on thermal neutrons are. The composite shielding material comprises materials prepared from the following raw materials in percentage by weight: 0.01%-5% of B, 0.1%-30% of W-containing substance, 3%-50% of B4C, 40%-90% of aluminum or aluminum alloy and 0-8% of other substances. The composite shielding material has excellent neutron/gamma radiation shielding performance, good mechanical performance and processing performance and high degree of densification and is especially suitable for the field of neutron/gamma ray shielding.

The invention relates to a preparation method for a fiber-reinforced superhigh temperature ceramic matrix composite. The preparation method comprises the following steps: 1) adopting a slurry infiltration fibrous preform containing nano zirconium carbide and phenolic resin, and obtaining a fibrous tackified preform containing ZrC through curing-splitting or direct splitting; 2) using organic polymer as an organic carbon source precursor to infiltrate the fibrous tackified preform containing the ZrC, and splitting so as to obtain a ZrC-C composite porous intermediate; 3) using zirconium disilicide as a silicon source and a zirconium source to perform infiltration on the porous intermediate at the temperature of 1800-1950 DEG C so as to obtain the fiber-reinforced superhigh temperature ceramic matrix composite.

The invention relates to a method for enhancing density of a SiC/SiC ceramic matrix composite. The method comprises the following steps: (1) a SiC/SiC ceramic matrix composite with a certain densification degree is immersed in slurry, in which an organic precursor and SiC powder are uniformly dispersed, and impregnation is carried out in an environment of 5-10 KPa vacuum degree for 20-50 min; (2) a material which has undergone vacuum impregnation is dried and the dried material undergoes cross-linking and curing; (3) the cross-linked and cured material undergoes pyrolysis treatment; and (4) the material which has undergone pyrolysis treatment further undergoes densification process in the atmosphere of a gaseous precursor containing Si and C elements by a chemical vapor infiltration technology while infiltration temperature is 850-1100 DEG C, pressure intensity is 10-20 KPa and infiltration time is 4-30 h. The method provided by the invention has advantages of simple operation, short densification time, good repeatability and high densification efficiency and has obvious advantages in the aspect of filling material voids. The method is a method with operability and development prospect.

The invention discloses a high-oriented high-strength array drawn carbon nanotube film and a preparation method thereof. The preparation method comprises the following steps: firstly, preparing a spinnable carbon nanotube array; then, winding the spinnable carbon nanotube array by using an array film-drawing method so as to obtain a dry-spun oriented carbon nanotube film, and improving the densification and orientation of the dry-spun oriented carbon nanotube film by using a method of solvent impregnating-drying by distillation; and finally, carrying out compaction treatment on the carbon nanotube film so as to obtain a high-oriented high-strength array drawn carbon nanotube film. The preparation method provided by the invention is simple in operation and strong in controllability; and the prepared high-oriented high-strength array drawn carbon nanotube film has a unique internal aggregation structure and excellent mechanical properties, and has great development potential and application value in the fields of structural materials, electronic devices, solar cells, and the like.

The invention discloses a tungsten/copper gradient material and a preparation method thereof. The tungsten content and copper content in the tungsten/copper gradient material are in continuous gradient distribution, the tungsten content is gradually increased from one side to the other side, and the copper content is gradually reduced; and the gradient material has high densifying degree, uniformmicrostructure, continuous ingredient gradient distribution and good overall performance. The preparation method comprises the following steps of: loosely loading W powder to the bottom of a quartz crucible; mixing Al powder and Cu2O powder, compacting, then placing the mixed powder of the Al powder and the Cu2O powder on the W powder in the quartz crucible, placing the quartz crucible in a supergravity infiltration device, vacuumizing, and electrifying a tungsten wire to initiate a reaction under the supergravity condition so as to obtain the tungsten/copper gradient material; and the preparation method disclosed by the invention has a simple process, low cost and high efficiency.

The invention discloses a synthesis method of an SiC-containing ceramics precursor, which comprises the steps that: 1. low molecular weight polymer with main chain containing silicon is sent into a three-mouth flask, and is added with 0.5wt% - 20wt% of tantalum organic compounds or chloride; 2. under the protection of Ar or N2 or compound of the Ar or N2, the temperature of the three-mouth flask is raised to 350 to 500 DEG C, and the temperature of a cracking column is controlled within 450 DEG C to 550 DEG C; then thermal decomposition rearrangement reaction is carried out for 0.5 to 25 hours, and then cooling is done; 3. the obtained rough product is dissolved by xylene and filtered; the filtrate solution is distilled by reducing temperature to between 250 to 390 DEG C, then the obtained material is cooled. The invention has the advantages of wide raw material source, reaction process being easy to be controlled, simple equipment, high purity of product, good formability, and good performance of super-high temperature and absorbing property; in addition, the ceramics fiber produced in the method has good oxidation resistance performance and is easy to realize large-scale industrial production.

The invention provides a mold-releasing type complexing agent with effects of resisting a high temperature of more than 1450 DEG C, insulating heat and demolding and a preparation method thereof. The mold-releasing type complexing agent comprises the following raw materials in percentage by weight: 20-60% of nano colloidal silicon dioxide solution; 5-30% of composite oxide ultramicro (0.1-1.0 microns) powder including Na, Mg, Ca, Fe, Li, Al, Si, B, Zr and other elements; 0.2-2% of water-based dispersing agent;0.02-0.5% of water-based thickening agent and the balance of water; and the sum of the weight of the components is 100%. According to the mold-releasing type complexing agent with effects of resisting high temperature, insulating heat and demolding, the nano colloidal silicon dioxide solution is cooperated with the ultramicro (0.1-1.0 microns) multielement composite oxide powder, so that the excellent performances of high temperature resistance, heat insulation, demolding, environment protection and the like are achieved, the thermal fatigue resistance of the mold surface is effectively improved, and the service life of the mold is prolonged. The mold-releasing type complexing agent with effects of resisting high temperature, insulating heat and demolding is particularly applicable to using at the part of a mold directly contacting molten steel in fired mold casting and other high temperature forming technologies of metal.

The invention provides a high-density Ti2AlNb powder alloy near-net forming technology.The technology comprises the following steps that 1, a Ti2AlNb alloy bar is smelted by taking components of Ti2AlNb-based alloy as ingredients; 2, the alloy bar processed through finish turning is put into plasma rotation electrode powder preparing equipment, and the Ti2AlNb alloy bar is prepared into Ti2AlNb spherical powder under the inert gas shielding condition; 3, the prepared Ti2AlNb spherical powder is located into a stainless steel or low-carbon steel sheath; 4, the sheath which contains the Ti2AlNb spherical powder and is compacted through vibration is degassed; 5, hot isostatic pressing forming is performed on the degassed sheath.The Ti2AlNb powder alloy prepared through the method has the isotropic character and is high in density degree, uniform in tissue and component, excellent in mechanical property and capable of achieving Ti2AlNb alloy parts with the large size and complex shapes.

A low-temp sintered AIN-base composition is prepared from AIN (50-80 wt%), lead borosilicate glass (15-50), and LiF (rest) through hot pressing and sinter, including heating and pressurizing by threestages, and holding temp at 950 or 1000 deg.C under 18-25 MPa for 2-8 hr. Its advantages include low sinter temp and density, high heat conductivity (11 W/m.k) and low cost.

The invention discloses a preparation method of a low-cost boron carbide/aluminum composite board and the preparation method can be used for simplifying a preparation process of a B4C/Al neutron absorption board and lowering the cost. The preparation method comprises the following steps: preparing a mixture, molding a powder compact and rolling. Compared with a traditional B4C/Al composite preparation technology, the preparation method has the advantages that long-time sintering is not needed, a pressed green compact is directly subjected to hot rolling after being subjected to vacuum heating, and the pressed green compact forms a compact green compact body by virtue of control of a hot rolling process, so that a composite board is obtained. the process flow is effectively shortened and the production cost and the energy consumption are reduced on the premise of ensuring the board quality, and the preparation method has the advantages of short production period and low energy consumption. The composite board prepared by the preparation method is high in quality, low in impurity content, good in B4C distribution uniformity and excellent in strength and tenacity matching, can meet the demand of the neutron shielding field, and is suitable for serving as a neutron absorption material in a reactor spent fuel water pond and a transport container and used for controlling the critical safety of a spent fuel storage environment.

The invention relates to a carbon fiber reinforced carbon-silicon carbide-zirconium carbide composite material and a preparation method thereof. The method comprises the following steps: (1) depositing a pyrolytic carbon matrix on the surface of carbon fibers contained in a carbon fiber preform to obtain a modified carbon fiber preform; (2) preparing a mixed resin solution of silicon powder, zirconium powder, graphite powder and phenolic resin in a mass ratio of (1-3): (4-6): 5: 100; (3) impregnating the modified carbon fiber preform with the mixed resin solution, and then sequentially carrying out curing and carbonization reactions on the impregnated modified carbon fiber preform, wherein the carbonization reaction is carried out in an inert atmosphere, the temperature of the carbonization reaction is 1650-1750 DEG C, and the time is 0.5-2 hours; and (4) repeating the step (3) at least once to obtain the composite material. According to the invention, silicon carbide and zirconium carbide can be uniformly distributed in the composite material, the content of free metals is reduced, and the oxidation resistance and ablation resistance of the material are improved.

The invention discloses a hot isostatic pressing forming method used for improving the part surface quality. The hot isostatic pressing forming method comprises the following steps that three-dimensional models of a wrapping sleeve and a shape control die core are designed according to the shape and size of a formed part; the stainless steel wrapping sleeve and the carbon steel shape control die core are manufactured according to the manufactured three-dimensional models; a ceramic coating is sprayed on the surface of the shape control die core through a physical vapor deposition (PVD) method; the shape control die core is fixed in the wrapping sleeve, and the wrapping sleeve is filled with powder and shaken to be compacted; the wrapping sleeve is subjected to air exhausting and heating treatment, sealing welding is conducted when the vacuum degree in the wrapping sleeve reaches a certain degree; the wrapping sleeve is subjected to hot isostatic pressing treatment through a technique that the temperature is increased at first and then the pressure is increased so as to make the powder be tightened and compacted under the action of the high temperature and the high pressure; and the wrapping sleeve and the shape control die core are removed to obtain the final part. According to the hot isostatic pressing forming method, the carbon steel die core with the coating serves as the shape control die core, and element diffusion between carbon steel cores and the powder can be effectively prevented; element segregation of the alloy surface due to diffusion is avoided, and the alloy surface quality is improved.

The invention discloses a piezoelectric material for lead-free piezoelectric ceramic with potassium-sodium niobate and a preparing method, which strengthens the ferroelectric performance of potassium-sodium niobate ceramic and further improves the piezoelectric performance. The material of the invention comprises anhydrous potassium carbonate, natrium carbonicum calcinatum, niobium pentaoxide and dibismuth trioxide, the stoichiometric proportion of the lead-free piezoelectric ceramic is (K0.5 Na0.5) Nb3 + x weight percent Bi 2O3, wherein the x is more than or equal to 0 and less than or equal to 1, the piezoelectric material for lead-free piezoelectric ceramic with potassium-sodium niobate is obtained through mixture making, drying and burnishing, granulation, molding, sintering and after polarization by a silver electrode; therefore, the densification of the ceramic is improved, polarized drain current of the ceramic is reduced, and the polarization process is carried out more easily; moreover, the piezoelectric material adopts the material from a conventional process and industry, has the characteristics of good process stability and no pollution.

The invention belongs to the field of refractory matters for ferrous metallurgy and in particular relates to an Al2O3-SiC-C refractory brick for a torpedo ladle produced by utilizing a waste Al2O3-C material and a preparation method of the Al2O3-SiC-C refractory brick. The Al2O3-SiC-C refractory brick comprises the following raw materials in percentage by weight: 10-40% of special grade bauxite clinker particles with the particle size of 3-5mm, 10-30% of special grade bauxite clinker particles with the particle size of 1-3mm, 5-20% of alundum particles with the particle size of 0.088-1mm, 5-20% of corundum fine powder with the particle size of less than 0.088mm, 2-8% of silicon carbon particulates with the particle size of 0.088-1mm, 2-8% of silicon carbon fine powder with the particle size of less than 0.088mm, 10-25% of waste Al2O3-C material fine powder with the particle size of less than 0.088mm, 5-15% of alumina micro powder with the particle size of less than 0.088mm, 3-10% of binding clay fine powder with the particle size of less than 0.088mm, 1-10% of crystalline flake graphite powder with the particle size of less than 0.088mm, 0.5-5% of asphalt powder with the particle size of less than 0.088mm, and 4-8% of additional phenolic resin.

The invention discloses a method for preparing C-mixed multi-core MgB2 super-conduction wires through a solution coating method and belongs to the technical field of super-conduction wire manufacturing. A MgB2 super-conduction core wire, a metal Nb-Ti composite blocking layer, a center copper-niobium reinforcing core and an outer-coating Cu-Ni alloy layer are included. First, a solution coating technology is used for preparing a C-mixed tubing precursor powder body, then the tubing precursor powder body is placed into a Nb-Ti composite tube cleaned by acid pickling in a filling mode manually, rolling is carried out, single-core wires are formed by machining, then secondary assembling is carried out according to a seven-core conductor structure, outer-coating materials are a Cu-Ni alloy tube, a center is reinforced through a copper-niobium composite rod, a secondary composite body is subjected to a machining process with rotary swaging drawing and hole pattern rolling combined, multi-core wires are prepared, and finally after heat treatment, the high-mechanical-strength high-critical-current-density C-mixed multi-core MgB2 super-conduction wires are obtained. The wires can be used in fields such as power transmission and distribution, super-strong magnets, energy storage, power generators, transformers and medical treatment.

The invention provides a preparation method of an aluminum-scandium alloy sputtering target material, and relates to the technical field of target material preparation. The preparation method of the aluminum-scandium alloy sputtering target material comprises the following steps that an aluminum source and a scandium source are mixed, and vacuum melting is conducted on an obtained aluminum-scandium alloy ingredient to obtain a molten aluminum-scandium alloy liquid; vacuum gas atomization is conducted on the molten aluminum-scandium alloy liquid by using an inert gas flow to obtain aluminum-scandium alloy powder; outer sheathing and hot isostatic pressing molding are sequentially conducted on the aluminum-scandium alloy powder to obtain an aluminum-scandium alloy sputtering target blank; and the aluminum-scandium alloy sputtering target blank is bound and machined to obtain an aluminum-scandium alloy sputtering target material. According to the method, the vacuum gas atomization is conducted by using the inert gas flow, contact between the molten aluminum-scandium alloy liquid and oxygen is isolated, the prepared aluminum-scandium alloy powder is high in sphericity degree, low in oxygen content, and uniform in grain structure, particle size and microstructure, and the aluminum-scandium alloy sputtering target material obtained by utilizing hot isostatic pressing molding is highin density, uniform in chemical component, and free of the defects such as segregation.

The invention belongs to the field of surface treatment of carbon fiber reinforced ceramic-based composites and particularly discloses a surface treatment method of a C/TiB2 composite. The C/TiB2 composite is embedded in B4C powder and treated at the temperature of 950-1,100 DEG C under the vacuum condition; Ti powder, NH4Cl and Al2O3 powder are mixed uniformly, and mixed powder is obtained; the obtained mixed powder is used for embedding the treated C/TiB2 composite, and the C/TiB2 composite is subjected to a reaction at the temperature of 1,200-1,300 DEG C under the vacuum condition for 3-5 h and then naturally cooled. According to the method, a B4C layer is firstly deposited on the surface of the composite, Ti powder and residual silicon react to produce TiSi2, besides, the Ti powder can react with B4C on the surface to produce TiB2, and the performance of the composite is further stabilized.

Disclosed is a preparation method of a zero-expansion LAS/SiC composite material. The method comprises: firstly, preparing LAS powder via a powder sintering method; then adopting SiC powder with a matching diameter as a conditioning agent of the zero-expansion LAS/SiC composite material; calculating the ratio of LAS powder and SiC powder for macro-control of the thermal expansion coefficient of the composite material; and finally adopting a hot pressed sintering method and post-process treatment to prepare the zero-expansion LAS/SiC composite material. The composite material obtained in the invention is high in densification degree. A matrix is softened at a high temperature, so that densification is beneficial to perform. Further, the externally-applied pressure quickens the densification process, so that pores, which cannot be discharged in the absence of pressure, can be forced to be eliminated under the action of stress. Organization is homogenized; the pore ratio is reduced; and the strength of the composite material is improved.

The invention discloses an ablation-resistant fiber toughened Si-B-C-N-Zr ceramic matrix composite as well as a preparation method and an application thereof. The preparation method of the ablation-resistant fiber toughened Si-B-C-N-Zr ceramic matrix composite comprises the following steps: S1, preparing Si-B-C-N-Zr powder; S2, performing surface modification treatment on fiber to obtain modifiedfiber; S3, mixing the modified fiber with the Si-B-C-N-Zr powder to obtain composite powder; S4, performing hot pressing and sintering on the composite powder to prepare the ablation-resistant fiber toughened Si-B-C-N-Zr ceramic matrix composite. The prepared ablative-resistant fiber toughened Si-B-C-N-Zr ceramic matrix composite has good microstructure and higher fracture toughness, mechanical property and ablative resistance, used raw materials are widely sourced and low in price, the preparation process is simple and mature, the preparation period is short, all the steps can be realized with existing technologies and equipment, and the composite is suitable for industrial production.

The invention discloses a construction method for densifying the surface layer of middle/low-strength concrete, which relates to the technical field of concrete construction. The middle/low-strength concrete is poured by a concrete temperature and humidity preservation maintenance template which is disclosed in a patent with the patent number of 2009200384330. The mixing proportion of the middle/low-strength concrete is optimized, the using amount of a gelatinization material and the using amount of water are controlled, the ratio of the water to the gelatinization material is also controlled, and the early-stage maintenance of the concrete is enhanced, so the ratio of the water to the gelatinization material of the concrete of the surface layer can be maximally reduced, the compactness and durability of the concrete can be improved, the surface layer densifying degree of the middle/low-strength concrete can be improved, the generation of temperature shrinkage cracks of the concrete can be prevented and the full development of the strength of the concrete is ensured.

The invention relates to a multi-component borosilicate glass and aluminum nitride low-temperature co-fired ceramic material and a preparation method thereof. The material comprises a low-melting point multi-component glass phase and an aluminum nitride ceramic phase, wherein the mass fraction of the low-melting point glass phase in the composite material is 50-70 wt%. The sintering temperature of the low-temperature co-fired composite material prepared by the preparation method is low, the sintering can be realized at the temperature of 750-850 DEG C, and the sintering temperature is far lower than an upper limit (950 DEG C) of the sintering temperature of the existing LTCC (low-temperature co-fired ceramic) material; the thermal conductivity of the composite material is relatively high, and the obtained material has the advantages of high density and low porosity. In addition, the process flow for preparing the material is simple, and the cost is low.