54results about How to "Alleviate thermal expansion mismatch" patented technology

The invention discloses an electrochemical method for preparing a HA/ZrO2 (hydroxylapatite/zirconia) gradient coating on the surface of medical titanium. The method comprises the following steps of: carrying out electro-deposition in an electrolytic cell with a three-electrode system, wherein the medical titanium to be coated is a working electrode; carrying out electro-deposition to obtain a Zr (OH) 4 coating in a zirconium oxynitrate solution with certain concentration and pH value, wherein the deposition current is 20mA, and the deposition time is 600s; then, depositing a CaHPO42H2O coating in an electrolyte which has certain concentration and pH value and consists of calcium nitrate and ammonium dihydrogen phosphate, wherein the deposition current is 1.5mA, and the deposition time is 900s; and finally, carrying out vacuum sintering on the obtained coating materials, and raising the sintering temperature to 650 DEG C at a heating rate of 10 DEG C/min, then preserving the heat for two hours, and subsequently cooling the coating materials with a furnace so as to obtain the HA/ZrO2 composite coating. The electrochemical method of the invention has the advantages that: the ingredients of the coating are deposited on a substrate in the form of ions, so that the bonding strength of the HA/ZrO2 gradient coating and the Ti substrate is improved greatly; and the anti-corrosion and simulated body fluid experiment shows that even the HA on the surface is dissolved completely due to the biological effect, the remaining ZrO2 coating still has good anti-corrosion performance and certain biocompatibility.

The invention discloses a method for strengthening a surface of a laser-clad titanium alloy. The method comprises the following steps: 1), pretreatment of the to-be-clad surface of a titanium alloy substrate, namely removing an oxide film on the to-be-clad surface of the titanium alloy substrate; 2), preparation of a cladding material, namely preparing the cladding material from NiCrBSi alloy powder and TiC according to the condition that the volume ratio of NiCrBSi to TiC is (50-100):(0-50), and mixing evenly; 3) pre-application of the cladding material, namely blending the evenly mixed cladding material with a volatile organic solvent into a paste, coating the to-be-clad surface of the titanium alloy substrate with the plaste so that the coating layer is 0.6-1.5mm thick, and then drying the coating layer; 4) laser cladding, namely irradiating the coating layer by use of a laser so that the coating layer is clad on the titanium alloy substrate. The method is capable of reducing thermal expansion mismatching of the coating layer, reducing residual stress and improving the properties of the coating layer.

The invention relates to a ceramic composite material for titanium alloy surface laser cladding. The ceramic composite material is prepared by mixing 20-65wt% of Ti powder, 25-75wt% of TiBCN ceramic powder and 2-10wt% of B4C powder. The ceramic composite material has the advantages that composite ceramic cladding coating metallurgically bonding with a titanium alloy matrix is formed on the surface of titanium alloy through the laser cladding technology, coating hardness can reach 3.5-4.5 times of that of the titanium alloy matrix, coating wear resistance is increased evidently, and a sample wear rate is only 1/3-1/4 of that of the titanium alloy matrix and is lowered evidently as compared with that of the matrix; multiple laser cladding operation can be repeatedly performed on the surface of the titanium alloy so as to regulate cladding coating thicknesses according to needs.

The invention discloses a carbon fiber surface C/Si (carbon/silicon) composite coating and a preparation method thereof. The carbon fiber surface C/Si composite coating is prepared by using SiCl4 and CH4 as raw materials, using Ar as protective gas and carrier gas, using H2 as reduction gas and using a negative pressure chemical vaporous deposition method. The prepared pyrolytic carbon coating has thickness of about 0.3 to 1mum. The prepared Si-system outer coating has thickness of about 0.5 to 1.2mum. The prepared coating is uniform, compact and flat and has excellent combination among layers. According to the invention, on one hand, the oxidation resistance of carbon fibers is improved and the high-strength performance of the carbon fibers is protected, and on the other hand, the wettabilities of the carbon fibers and a metal matrix are improved and the success rate of preparation of the composite material is greatly improved.

The invention relates to an oxidation-resistant material and a method employing the same for preparing a tantalum-tungsten alloy anti-oxidation coating. The oxidation-resistant material is characterized by comprising a first anti-oxidation material and a second anti-oxidation material, wherein the first anti-oxidation material comprises 1-5wt% of Cr, 1-5wt% of Ti, 0.1-2wt% of Y2O3, 0.5-3wt% of W, 0.5-3wt% of Nb, 1-5wt% of HfO2, and the balance Si; the second anti-oxidation material comprises 6-15wt% of Mo, 0.5-3wt% of W, 0.5-3wt% of Nb, 0.3-2.2wt% of Y, 1-5wt% of HfO2, and the balance Si. The tantalum-tungsten alloy anti-oxidation coating prepared by the method has a wide operating temperature range, and is high in continuous static load and antioxidant capacities, and is particularly suitable for high-temperature structural components such as a thrust chamber, a nozzle jet, a front edge and a guide tube of an airspace engine.

The invention provides an eight-beam symmetrical silicon micro-accelerometer. The capacitive micro-accelerometer comprises three portions of an upper silicon electrode plate, a sensitive chip and a lower silicon electrode plate from top to bottom, wherein the sensitive chip is of a micro-structure of 'mass block-cantilever beams'; eight cantilever beams are provided, and symmetrically distributed around a mass block, and the mass block is located at a middle horizontal position; the thickness of the mass block is the same as that of the adopted silicon slice, and the shape is a polygon so as to effectively utilize the space, thus the quality is greatly improved, and a lower device noise and a higher sensitivity can be obtained; the micro-accelerometer adopts an all-silicon process, the silicon electrode plates are bonded with the sensitive chip through silicon-silicon fusion, thus problems of thermal expansion coefficient mismatching and the like can be reduced; the patterns of the mass block and the beams are formed on the surface of the silicon slice through a double-layer SiO2 process, thus deep-groove photoetching is avoided. The eight-beam symmetrical silicon micro-accelerometer provided by the invention is high in stability, low in device noise, and capable of improving the measurement accuracy of the accelerometer.

An improved multilayer coating for use on molten metal holding and transfer apparatus, the coating including a bound layer applied directly to the surface of molten metal holding and transfer apparatus, and a porous layer of ceramic material produced by co-deposition of a powder of said ceramic material and a powder of a suitable organic polymer material and, after the co-deposition, heating of said polymer material to thermally decompose the polymer material and form the porous layer. The bond layer preferably is formed of a metallic, intermetallic or composite particulate materials. The metal component may be in the metallic, intermetallic, oxide, clad or alloyed form consisting of any one or more of the metal components selected from the group of Mo, Ni, Al, Cr, Co, Y and W and may be in combination with yttria, alumina, zirconia, boron, carbon and have a particle size in the range of 5 to 250 m, typically 40 to 125 m. The bond layer preferably has a thickness of 5 to 300 m with a substantially uniform coating layer being provided over the surfaces to have the porous ceramic coat applied.

The invention discloses a heat-insulation-and-bearing-integrated carbon aerogel and ceramic layered composite material and a preparation method and application thereof, and belongs to the technical field of a carbon aerogel and ceramic composite material. The composite material comprises a high-strength carbon aerogel body layer, a function gradient SiC and carbon aerogel transition layer, and a superhigh-temperature ceramic and SiC antioxidant composite coating. The high-strength carbon aerogel body layer is made through five steps of solution preparation, sol-gel, solvent replacement, normal-pressure drying and high-temperature carbonization through normal-pressure drying technology. The function gradient SiC and carbon aerogel transition layer is made by deep deposition of SiC on a carbon aerogel surface through a chemical vapor infiltration process. The superhigh-temperature ceramic and SiC antioxidant composite coating is made through compound technology of spraying and chemical vapor deposition. The composite material is good in ablation and oxidation resistance, low in thermal conductivity and density, and high in strength, can resist high temperature as high as 1800 DEG C, and is suitable for heat-insulation materials of aircrafts.

The invention discloses a W/Si3N4/W symmetrical laminated gradient composite material as well as a rapid preparation method and an application thereof, and belongs to the technical field of preparation for ceramic matrix composite materials. According to the tungsten/silicon nitride/tungsten symmetrical laminated gradient composite material as well as the rapid preparation method and the application thereof, the W/Si3N4/W symmetrical laminated gradient composite material is prepared through an SPS sintering technology; in the method, an electric field is further introduced on the basis of a temperature field and a pressure field, a plasma activation effect on raw materials can be acted, so that a compact composite ceramic material can be rapidly prepared under the conditions of a low sintering temperature and a short heat-insulation time; and meanwhile, the activation effect of plasmas also contributes to the diffusion of atoms, then the interlayer bonding of W and Si3N4 can be promoted, and the high-performance connection between W and Si3N4 is realized. The method has the advantages of being high in heating speed, low in sintering temperature and short in heat-insulation time, and the W/Si3N4/W symmetrical laminated gradient composite material with high compactness, low impurity content and good interface bonding can be rapidly prepared via the method.

Certain example implementations of the disclosed technology include an optical-interferometer sensor assembly for measuring pressure or acceleration. The sensor assembly includes a diaphragm configured to deflect responsive to an applied stimulus, a diaphragm support structure in communication with the diaphragm, a sensing optical interferometer having a first optical cavity in communication with at least a portion of the diaphragm and the diaphragm support structure, and a reference optical interferometer having a second optical cavity in communication with the diaphragm support structure. The sensor assembly can include a sensing optical fiber in communication with the sensing optical interferometer and a reference optical fiber in communication with the reference optical interferometer. The sensor assembly can include a housing in communication with the diaphragm and the diaphragm support structure, and configured to reduce a thermal expansion mismatch in the sensor assembly.

The invention relates to a local fast heating experimental device for a novel ultra-high temperature ceramic test piece. The local fast heating experimental device is characterized in that a positive pole and a negative pole of amplified voltage U0 are connected to the left and right sides of a copper electrode respectively and is connected with a positive pole and a negative pole of an amplifying circuit respectively, the amplifying circuit is connected with a positive pole and a negative pole of input voltage Ui, the copper electrode is connected with a thermocouple which is placed within a measurement range of an infrared thermometer, the infrared thermometer is connected with a computer through a data line, and the amplifying circuit is used for supplying power through a direct-current source. The local fast heating experimental device is used for local fast heating of the ultra-high temperature ceramic test piece.

The invention relates to a multiphase environmental barrier coating formed on a base material and a preparation method thereof. The multiphase environmental barrier coating sequentially comprises a silicon bonding layer, a mullite layer and a Lu2SiO5-Sc2Si2O7 multiphase ceramic layer from the base material to the outside, wherein the Lu2SiO5-Sc2Si2O7 multiphase ceramic layer is formed by mixing lutetium silicate and scandium silicate. The method comprises the following steps: filling silicon powder, mullite powder and mixed powder formed by mixing lutetium silicate powder and scandium silicatepowder into a powder feeder of ultra-low pressure plasma spraying equipment and carrying out drying treatment; fixing the base material to a rotating table in a spraying cabin; and sequentially preparing the silicon bonding layer, the mullite layer and the Lu2SiO5-Sc2Si2O7 multiphase ceramic layer on the surface of the base material to prepare the multiphase environmental barrier coating. The multiphase environmental barrier coating is long in thermal shock resistance life and excellent in high-temperature water-oxygen corrosion resistance; and the method provided by the invention can be usedfor rapidly and integrally preparing the multiphase environmental barrier coating at low cost in an ultra-low pressure environment.

By cutting a surface of a CMC component which has to receive a TBC a rough surface is yielded, which is rough enough to have a good adhesion of a following ceramic coating.

The invention discloses a preparation method of a barrier layer yttrium oxide-doped bismuth oxide of a solid oxide fuel cell, and belongs to the technical field of preparation of a battery material. The preparation method comprises the following steps of 1, taking Bi(NO<3>).5H<2>O and Y(NO<3>).6H<2>O as the raw materials, and preparing Y<x>Bi<2-x>O<3> powder through a coprecipitation method; 2, adding ethyl cellulose into Y<x>Bi<2-x>O<3>; 3, adding terpilenol, and grinding for 10-30min through an agate mortar; 4, performing silk screen printing on the obtained Y<x>Bi<2-x>O<3> paste on an electrolyte; 5, performing drying; 6, performing silk screen printing and drying for 1-3 times repeatedly to obtain Y<x>Bi<2-x>O<3> barrier layers of different thicknesses; and 7, performing heat treatmenton the electrolytes of the Y<x>Bi<2-x>O<3> barrier layers. The preparation method has the advantages as follows: by taking Y<x>Bi<2-x>O<3> with high oxygen ionic conductivity as the barrier layer, the problem of mismatching of coefficients of thermal expansion between a negative electrode and the electrolyte and between the barrier layer and the electrolyte can be effectively relieved, a reactionbetween a cobalt-based and a barium ferrite-based negative electrode material and a zirconium-based electrolyte can be avoided, and the interface resistance can be lowered; and the preparation methodis free of complex equipment, simple in preparation process, low in cost, and amplification and popularization can be realized easily.

The encapsulation structure includes lead frame, first and second chips and leads. The lead frame possesses following parts: first chip seat including opposite first face for sticking chip and first face for not sticking chip; second chip seat including opposite second face for sticking chip and second face for not sticking chip; structure for connecting first and second chip seats, and for connecting chip seats faced to first face for sticking chip and second face for not sticking chip; inner pins with connection faces for leads. First chip possesses first not active surface opposite to first active surface with first pads. The first not active surface is stuck to part of first face for sticking chip. Second chip possesses second not active surface opposite to second active surface with second pads. Part of second active surface is stuck to the second face for sticking chip. The said second face avoids covering second pad. Conducting wire connects first and second pads.

The invention discloses a palladium/ceramic composite film. The composite film is loaded on a porous carrier. The composite film is formed by combining metal palladium or a palladium alloy and ceramics, wherein the volume of the palladium or the palladium alloy accounts for 30%-99%. The composite film is prepared through a physical vapor deposition method. A magnetron sputtering method is preferably adopted for preparing, and the composite film is obtained through sputtering of a palladium or palladium alloy target and a ceramic target at the same time. Through combining of a palladium film and the ceramics, on one hand, ceramic particles are dispersed and distributed in the continuous palladium or palladium alloy, the function of pinning is achieved for the palladium grain boundary, and palladium grain high-temperature grain growth and roughening difficulty is increased; and on the other hand, through introduction of the ceramics, the function of adjusting the palladium film heat expansion coefficient can be achieved, palladium film and ceramics or glass heat expansion mismatching is reduced, and the high-temperature structure stability of the palladium film is improved.

The invention discloses a composite structure friction material and a preparation method thereof. The composite structure friction material of the present invention includes at least one inner layer group and at least one outer layer group, the part near the friction surface is the outer layer group, the part far from the friction surface is the inner layer group, and the inner layer group is straight and continuous carbon fiber Reinforced structure layer group, the outer layer group is carbon fiber corrugated continuous reinforced friction layer group; the inner layer group and the outer layer group are connected by needle-punched carbon fiber. The invention also includes a preparation method of the composite structure friction material. The friction material prepared by the present invention adopts the straight continuous carbon fiber reinforced structure of the inner layer group and the continuous corrugated carbon fiber reinforced structure of the outer layer group with gradient changes. The materials for the main bearing function and the main friction function adopt different structures, which can be Guarantee the excellent comprehensive performance and friction performance of the friction material.

The invention discloses a kind of weight reduced, large-bore, and compound reflector. It includes a compound lens which is composed of folded graphite fiber/ wreath oxygen resin or graphite fiber/ cyanic acid fat panel + beehive interlayer + graphite fiber/ wreath oxygen resin or graphite fiber/ cyanic acid fat panel. It has these characteristics: On the lens, there are a microlite cylinder array and a tiny glass reflection base which are both fixed by wreath oxygen resin; On the microlite reflection base, a metallic reflection layer which is plated in vacuum exists. The advantages of the invention are as follows: It takes the microlite cylinder array as the join linking the carbon fiber compound material lens and the microlites reflection base so that the compound material lens can match the microlites reflection base's coefficient of heat expansion well and the problem of the mirror surface's anamorphic caused by heat can be solved. Moreover, the fact that the microlites reflection base has a good optical surface guarantees the reflector's heat stability and chemical stability.