3918results about How to "Small coefficient of thermal expansion" patented technology

The invention discloses a concentric-ring sprayer structure for material vapor phase epitaxy, which solves the problem that the large-area deposition region provides a uniform flow field of a precursor gas mixture in a large-substrate or multi-substrate crystal growth process. The sprayer structure comprises more than one independent air inlet pipeline, wherein each air inlet pipeline is provided with a controller for monitoring and regulating inlet gas flow speed and flow rate; the bottom of the sprayer is provided with an air outlet baffle; more than one concentric ring is arranged in the sprayer; independent cavities are formed among the concentric rings and are mutually separated; the top end of each concentric ring is connected with one independent air inlet pipeline; and the air outlet baffle at the bottom end of each concentric ring is provided with one or more air outlets. The air sources are mutually separated and independently controlled; and the multi-sprayer integrated use mode obviously improves the quality of the large-area deposited grown crystal, and greatly enhances the production efficiency.

The invention relates to a low thermal expansion coefficient NaMxAlySiz high entropy alloy and a preparation method thereof, the chemical components of the alloy are as follows: 75 <= a <= 100%, 0 <= x <= 10%, 0<= y<= 10%, 0<= z<= 5%, N is arbitrary three or more than three of Ta, Nb, Hf, Zr, Ti, Mo and W, and M is any one or more than one of V, Mn, Fe, Co, Ni and Cr. The alloy phase structure is as follows: a body centered cubic solid solution and an intermetallic compound. The alloy is prepared by arc melting method in three stages. The NaMxAlySiz high entropy alloy has a low thermal expansion coefficient at the temperature in the range of room temperature to 1000 DEG C, the change rate is less than 20%, and the alloy has a broad application prospect in the high temperature industrial field.

The invention relates to a production method of once-fired super-spar ceramic tile and the ceramic tile. The production method of the once-fired super-spar ceramic tile comprises the following steps: preparing green body powder; pressing a tile body; cleaning the green body; pouring ground glaze; printing; pouring overglaze; firing a glaze body at a high temperature; polishing; performing surface treatment; performing edge polishing; and packaging to obtain a finished product, wherein the overglaze comprises the following components in parts by weight: 5 to 13 parts of quartz powder, 3 to 20 parts of potassium feldspar, 20 to 28 parts of soda feldspar, 12 to 18 parts of dolomite, 3 to 6 parts of fired talc, 3 to 8 parts of kaolin, 14 to 22 parts of calcined kaolin, 3 to 8 parts of zinc oxide, 7 to 14 parts of barium carbonate and 3 to 6 parts of grammite. According to the invention, the problems that microlite has low wear resistance and is difficult to process in the prior art are solved, and the defect of water ripples caused by the situations that fully-polished glaze absorbs dirt, bottom is easy to expose and the tile surface is uneven is also solved. The super-spar product produced with the method has the advantages that the microlite is transparent, bright and smooth like a mirror and does not absorb dirt completely; and the fully-polished glaze is light, thin and wear-resistant.

The invention discloses an epoxy resin composition, a continuous glue film made of the same and a preparation method. The epoxy resin composition comprises solid ingredients and organic solvents, wherein the solid ingredients comprise epoxy resin (A), thermoplastic resin or/and synthetic nitrile rubber (B), solidified agents (C), curing accelerators (D) and inorganic heat-conducting fillers (E). In addition, the invention also relates to the continuous glue film made of the epoxy resin composition and the preparation method. Because the continuous glue film is made by automated equipment, thecontinuous glue film has good consistency on thickness and performance, so that the breakdown voltage of a metal based copper-clad laminate and the stability of thermal resistance are ensured. The product made by the invention has good heat-conducting performance and electric insulation performance.

The invention discloses a spherical silicon dioxide/polyimide composite film and a method for making the same as well as an application. The method for making the spherical silicon dioxide/polyimide composite film comprises the following steps that: 1) spherical silicon dioxide particles are scattered into an organic solvent evenly to obtain the spherical silicon dioxide particle suspension liquid; 2) a surface treatment agent, a molecular weight modifying agent, an auxiliary adhesive, a flatting agent and aromatic series diamine are dissolved inside the spherical silicon dioxide particle suspension liquid; organic dicarboxylic anhydride is added to be stirred in order to obtain a spherical silicon dioxide/polyamide acid mixing resin solution; 3) the mixing resin solution is coated on the surface of a flat substrate and is heated up to make the solvent volatilize and complete the imide reaction to obtain the spherical silicon dioxide/polyimide composite film. The spherical silicon dioxide/polyimide composite film has good mechanical property, good corona resistance, low thermal coefficient of expansion and low moisture absorption ratio, and has important application value in an insulating system of a frequency conversion speed motor.

The invention belongs to the technical field of preparation of electronic packaging materials, and particularly designs a copper-based composite material with high thermal conductivity and a preparation method thereof. The copper-based composite material is made of a reinforcement and a binder through a prefabricated injection molding process to make a reinforcement prefabricated part, wherein the size of the reinforcement particle is 7-60 μm, and it is composed of silicon carbide particles, diamond particles or aluminum nitride particles. One or two of them; the copper matrix is ​​directly placed on the reinforcement preform, wherein the copper matrix is ​​electrolytic copper or oxygen-free copper, and the volume ratio of the reinforcement to the copper matrix is ​​50-75%: 25-50 %, made by pressure infiltration process. The preparation method adopts the injection molding process of the prefabricated part and the pressure impregnation process to prepare the high thermal conductivity copper matrix composite material. The thermal conductivity of the copper-based composite material in the present invention is higher than that of the aluminum-based composite material with the same reinforcement system, the material itself has low density and small thermal expansion coefficient, which meets the requirement of light weight of the packaging material.

The invention discloses a high-resistance electrothermal alloy material, which comprises the following components in percentage by weight: 0.02 to 0.08 percent of C, 0.75 to 1.6 percent of Si, 0.1 to 0.5 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.015 percent of S, 20 to 23 percent of Cr, 0.1 to 0.5 percent of Al, 0.2 to 0.8 percent of Y, 0.2 to 1.0 percent of Fe, and the balance of Ni and inevitable impurities. The preparation method for the high-resistance electrothermal alloy material comprises the following steps of: smelting; forging; coiling; annealing; rinsing; mold drawing, and the like. Compared with Cr20Ni80, the high-resistance electrothermal alloy material has higher antioxidation performance, and is an electrothermal alloy material with small thermal expansion coefficient, high high-temperature strength and processability, long service life and high resistivity.

The invention relates to a preparation method of thermosetting polyimide film with high modulus and low coefficient of thermal expansion, which obtains an objective product by copolymerization, sol-gel process and condensation. Rigid diamine and dianhydride are adopted in the polyreaction. A sol-gel in situ method is adopted, the reaction process is easy to be controlled, the uniformity is good; the amount of hybridization of inorganic particles can be increased; and the obtained solution is heated step by step to generate condensation reaction. The preparation technique is simple and is easy to be controlled; and the obtained product has higher elastic modulus and low coefficient of thermal expansion; therefore, the invention has higher application value in industry.

The invention discloses a boron-modified organic silicon resin high-temperature-resistant coating which comprises the following components in percentage by mass: 45%-58% of boron-modified organic silicon resin, 35%-45% of heat-resisting pigment fillers and 2%-4% of auxiliary agents, wherein the boron-modified organic silicon resin is boric-acid-modified organic silicon resin or epoxy-modified silicon-boron resin; and the mass ratio of nanometer silicon dioxide to barrier function fillers to aluminum powder which are contained in the heat-resisting pigment fillers is 1.5:1:1. The invention also discloses a preparation method of the boron-modified organic silicon resin high-temperature-resistant coating. The preparation method disclosed by the invention can be implemented on an existing coating preparation production line without increasing equipment investment; the prepared high temperature-resistant organic silicon coating can be coated by adopting a spray coating process and constructed by adopting a roll coating process, can be subjected to high temperature of 800 DEG C for a long time and has corrosion-resistant property.

To provide an aluminum magnesium titanate crystal structure which can be used stably in variable high temperatures, because of its excellent heat resistance, thermal shock resistance, high thermal decomposition resistance and high mechanical property, and a process for its production.

An aluminum magnesium titanate crystal structure, which is a solid solution wherein at least some of Al atoms in the surface layer of aluminum magnesium titanate crystal represented by the empirical formula Mg_xAl_2(1−x)Ti_(1+x)O₅ (wherein 0.1≦x<1) are substituted with Si atoms, and which has a thermal expansion coefficient of from −6×10⁻⁶ (1/K) to 6×10⁻⁶ (1/K) in a range of from 50 is to 800° C. at a temperature raising rate of 20° C./min, and a remaining ratio of aluminum magnesium titanate of at least 50%, when held in an atmosphere of 1,100° C. for 300 hours.

The invention relates to a resin composition used for forming a dielectric layer of a dielectric substrate for an antenna. The resin composition comprises (A), epoxy resin containing a naphthalene nucleus or diphenyl structure, (B), any one of or a mixture of at least two of tri(4-hydroxyphenyl) methane type epoxy resin, o-cresol type novolac epoxy resin and phenol type novolac epoxy resin, (C), a resin fusion viscosity modifier, and (D), spherical ceramic powder after presintering treatment. With the adoption of the resin composition, the obtained dielectric substrate has a high dielectric constant, high peeling strength, a low thermal expansion coefficient and very good thickness consistency, and can meet a performance requirement of the high dielectric constant antenna substrate.

The invention provides a glaze for fast-fired crystal glaze ceramic tile and a preparation method and applications of ceramic tile. The glaze comprises basic crystal glaze and a color developing agent, wherein the basic crystal glaze comprises the following raw materials: zinc oxide, titanium dioxide, quartz, cryolite, zinc phosphate, kaolin, and lead frit. A proper amount of zinc phosphate is introduced into the glaze to avoid the raw material frit treatment, which is carried out to ensure the residual amount of nucleating agent, the requirements on the glaze granularity are reduced, the manufacture technologies of crystal glaze and ceramic tiles are simplified, and the technical difficulties that the crystal glaze sintering technology is complicated, the crystal patterns are difficult to control, and the production cost is high are solved. Moreover, the addition amount of quartz and lead frit is precisely controlled to obtain crystal glaze art ceramic tiles which have the advantages of good crystallization effect, strong three-dimensional effect, and good artistic effect. The provided preparation method has the advantages of simpleness, lower sintering temperature, shorter period, and suitability for massive industrial production.

A preparing method of a ceramic-filled polytetrafluoroethylene microwave composite-medium substrate is disclosed. The method includes 1) adding silicon dioxide ceramic powder into a liquid mixture of hydrogen peroxide and concentrated hydrochloric acid after the silicon dioxide ceramic powder is dried, and heating the mixture to 50-70 DEG C to obtain a suspension; 2) subjecting the suspension to suction filtration and drying a product in a vacuum environment; 3) adding the silicon dioxide ceramic powder obtained in the step 2) into a solution mixture of deionized water and absolute alcohol, adjusting the pH value to be 3-5, weighing a coupling agent the weight of which is 1.0-2.5% of the weight of the silicon dioxide ceramic powder, performing ball milling, and fully mixing the mixture to obtain a material mixture; 4) filtering and drying the material mixture to obtain modified silicon dioxide ceramic powder; 5) ball-milling and mixing the modified silicon dioxide powder, chopped glass fibers and polytetrafluoroethylene, and then performing demulsification to obtain dough; and 6) subjecting the dough to molding and hot-pressed sintering. The ceramic-filled material prepared by the method has a low dielectric constant (with epsilon being equal to 2.94), ultralow dielectric loss (with tg[delta] being less than 0.0008, 10 GHz), low water absorption (less than 0.02%) and a small thermal expansion coefficient (less than 20 ppm/DEG C).

The present invention relates to a magnesium alloy surface microarc oxidation method. Said method includes the following steps: (1), pretreatment; (2), preparing alkaline silicate electrolyte or alkaline aluminate electrolyte; and (3), placing the pretreated magnesium alloy in the alkaline silicate electrolyte or alkaline aluminate electrolyte and making microarc oxidation; applying DC current, continuously rising voltage, constant current, current density is 1-15 A/sq.dm, galvanization time is 5-90 min and electrolyte temperature is less than 40 deg.C.