30results about How to "Reduce thermal mismatch stress" patented technology

A refractory metal core system for use in casting a product is provided. The refractory metal core system comprises a refractory metal core and a layer of aluminum nitride deposited on the refractory metal core, which layer of aluminum nitride acts as a bond coat. The system may further comprise a layer of alumina deposited on top of the aluminum nitride layer.

The invention provides an YSZ-rare earth zirconate thermal barrier coating of a gradient structure and a preparation method thereof. The coating material comprises an adhesive layer, an 8YSZ-rare earth zirconate gradient layer and a surface layer. The 8YSZ-rare earth zirconate material has relatively low conductivity, high-temperature sintering resistance and excellent resistance to heat shocks, and also can prevent oxygen from entering the adhesive layer on active service to alleviate oxidization of the adhesive layer to form TGO. The heat mismatching stress of the material can be reduced bymeans of an optimized design of the gradient structure, so that the heat stability of the whole material member is improved; the surface layer is a CMAS corrosion layer, so that the problem that an existing YSZ coating is corroded by CMAS can be alleviated. As Pd or a oxide ceramic layer is adopted, CMAS molten at a high temperature is not wet in the surface layer, and the rolling angle is small,and CMAS is hardly attached to the surface of the coating, so that CMAS corrosion is avoided.

The invention discloses a metal workpiece double layer coating suitable for high temperature environment and a manufacturing method thereof. The manufacturing method of the metal workpiece double layer coating suitable for the high temperature environment includes the following steps of 1) pretreatment: degreasing the surface of a metal workpiece, sandblasting roughening and cleaning; 2) spraying:preheating the pretreated metal workpiece, adopting an atmospheric plasma spraying device for spraying, first spraying a ceramic inner layer on the surface of the metal workpiece, then heating and spraying a metal outer layer and then spraying a metal layer on the side of an obtained coating; 3) heat treatment: conducting vacuum heat treatment on the sprayed metal workpiece and conducting gas quenching. According to the manufacturing method, the metal layer is sprayed on the ceramic layer. On one hand, the high cost of ceramic precision machining is reduced; on the other hand, various corrosion-resistant or wear-resistant alloy materials can be applied. In addition, the melting point of metal is lower than that of the ceramic, and the mechanical properties of the coating can be changed bythe heat treatment process.

The invention discloses a full-silicon MEMS wafer-level vacuum packaging method based on anode bonding; two-time anode bonding is adopted in the MEMS wafer-level vacuum packaging process to realize mechanical and electric signal connection among a cover plate, an MEMS device structure and a substrate and form a pressure controllable MEMS sealing cavity; compared with the existing full-silicon bonding process based on silicon-silicon solder bonding and silicon-silicon fusion bonding, the method in the invention is low in process difficulty and high in rate of finished products; the cover plateglass sheet is thinned to 10-50 microns and the substrate glass sheet is thinned to 10 -50 microns; the thickness of the dielectric layer of the existing full-silicon bonding process is not more than3 microns to the maximum; the thinner dielectric layer is, the larger the introduced parasitic capacitance is; hence, the parasitic capacitance introduced by the method in the invention is small, so that the signal-to-noise ratio output by the MEMS device is improved.

This invention discloses a method for producing a non-polar compound GaN base substrate, in which, the structure of the substrate is reflection/ohm/stress buffer layer laminated between a support substrate and non-polar GaN base epitaxial layer, the method includes: growing an intermediate layer( or a germ layer) and a non-polar first GaN base epitaxial layer orderly on the substrate, laminating a mask layer, etching the mask layer to form a GaN window and mask layer strips, growing a non-polar second GaN base epitaxial layer, laminating the reflection/ohm/stress buffer layer, bonding the support substrate, peeling off the growing substrate, the intermediate layer, the non-polar first GaN base epitaxial layer, the mask layer strips and the cavity part in the non-polar second GaN base epitaxial layer and exposing the part without cavities to be heat-processed.

This invention discloses a conductive non-polar compound GaN substrate and a production method, in which, the conductive reflection/ohm/stress buffer layer is laminated between the conductive support substrate and the non-polar GaN epitaxial layer, the production method includes: growing an intermediate layer(or germ layer) and a non-polar first GaN epitaxial layer orderly on the growing substrate, laminating a mask layer, etching the mask layer to form a GaN window and mask layer strips, growing a conductive second GaN epitaial layer, laminating the conductive reflection/ohm/stress buffer layer, bonding the support substrate, peeling off the growing substrate, the intermediate layer, the first epitaxial layer, the mask layer and the second epitaxial layer with cavities to be heat-processed.

The invention relates to the technical field of thermal barrier coatings, in particular to a porous tantalite ceramic. The ceramic is prepared by sintering RE2O3 powder, Ta2O5 powder and HfO2 powder,the molar ratio of RE: Ta: Hf in the ceramic is 1:1: x, wherein the x is larger than 0 and smaller than 0.1; the ceramic is of a porous structure, and the porosity is larger than 0.2. The preparationmethod of the ceramic comprises the following steps of: weighing the RE2O3 powder, the Ta2O5 powder and the HfO2 powder, wherein the molar ratio of RE: Ta: Hf is 1:1:x, adding a solvent, mixing, and grinding by using a grinding machine to obtain powder A; drying the powder A, and sieving for the first time to obtain powder B; placing the powder B in a mold, compacting, and pre-sintering to obtaina block C; cooling the block C to room temperature, grinding by using the grinding machine, and sieving for the second time to obtain powder D; and sintering the powder D to obtain the porous tantalite ceramic. The porous tantalite ceramic prepared by adopting the technical scheme has the advantages of high porosity, low thermal conductivity at high temperature and good heat insulation performance.

The disclosed processing steps for a conductive non-polar composite GaN substrate comprise: on the growth substrate, growing middle medium layer (or crystal kernel) and the non-polar first GaN-based extension layer in turn; overlaying the mask layer to etch and form the GaN window and mask layer strip; growing the non-polar second GaN extension layer; overlaying the conductive reflection/ohm/stress buffer layer; bonding substrate; then, peeling the substrate, medium layer, the first extension layer, mask strip, and the part with hole on the second extension layer for thermal treatment.

An anisotropic coefficient of thermal expansion (CTE) cathode of a solid oxide fuel cell (SOFC) is formed by placing a layer of perovskite powder between two platens, and sintering the layer while applying pressure to the platens, thereby forming the anisotropic CTE cathode. The perovskite can be lanthanum strontium manganite (LSM).

A semiconductor package structure for a ball grid array type package using a plurality of pieces of adhesive elastomer film to attach a semiconductor die to a substrate having conductive traces in order to alleviate thermal mismatch stress between the semiconductor die and the printed circuit board to which the packaged device is soldered, while maintaining the reliability of the packaged device itself.

The invention discloses an aluminum-based composite material and a semi-solid preparation method thereof. The composite material comprises the following components in percentage by volume: 6-14% of ceramic particles and 86-94% of aluminum alloy. The preparation method comprises the steps of powder surface modification treatment, molten alloy liquid preparation, semi-solid slurry preparation, composite material blank preparation and composite material blank heat treatment. According to the method, the high-quality and low-cost composite material and the semi-solid near-net forming preparation thereof can be realized, the preparation of the high-quality aluminum-based composite material is realized through powder surface modification treatment, molten alloy liquid component design and a composite material heat treatment process, and the technological process is simple in flow, low in cost and high in yield.

The disclosed non-polar composite GaN-based substrate comprises overlays between the substrate and the GaN extension layer reflection/ohm/stress buffer layer. Wherein, the preparation method for the substrate comprises: on the growth substrate, growing middle medium layer (or crystal kernel) and the non-polar first GaN-based extension layer in turn; overlaying the mask layer; etching the mask to form the GaN window and mask layer strip; growing the non-polar second GaN extension layer; overlaying the reflection/ohm/stress buffer layer; bonding substrate; peeling the substrate, medium layer, the first extension layer, mask strip, and the part with hole on the second extension layer; exposing other part of the second extension layer for thermal treatment.