99results about How to "High ceramic yield" patented technology

The invention discloses a product and a preparation method thereof. The product is prepared by a light-curing rapid prototyping process, and a raw material used in the light-curing rapid prototyping process is a liquid photosensitive resin material. The product has an excellent mechanical property, and is high in tensile strength and tensile modulus, smooth and clean on surface, small in cure shrinkage, stable in size and good in mechanical property. The liquid photosensitive resin material contains liquid polycarbosilane having a line-ring structure and containing unsaturated double bond andis good in stability and easy to store, and the synthetic route of the material is green and environmentally friendly without corrosion; and a liquid line-ring polycarbosilane active group is large indensity, fast in curing speed, high in cured product strength, low in molecular weight and viscosity, good in fluidity and printable performance, and especially suitable for a 3D printing technologyof light-curing rapid prototyping.

The invention relates to a method for preparing polycarbosilane through cracking rearrangement of a cyclic silane compound or chain polysilane under the catalytic effect of trace (lower than 1wt%) boron-containing catalyst. According to the invention, polydimethylsilane (PDMS) or a pyrolysis product thereof which is a liquid-state silane-carbosilane compound (LPS) is adopted as a raw material; lower than 1wt% (relative to the amount of the raw material) of the boron-containing catalyst is added; the temperature is gradually increased to a reaction temperature under a normal pressure or a high pressure, such that a pyrolysis / rearrangement reaction is carried out, and solid-state polycarbosilane (PCS) with relatively high ceramic yield is obtained. The method provided by the invention has the advantages of short reaction time, high synthesis yield, good product quality, simple equipment and safe operation. The prepared polycarbosilane is a SiC precursor polymer, and can be used in the preparations of SiC fiber and SiC-based composite materials.

The invention discloses poly(methylsilane-carbosilane) and a preparation method thereof. The structural formula of the poly(methylsilane-carbosilane) copolymer is shown in formula I which is shown in the specification, wherein x=0-0.2, y=0.03-0.2, z=0-0.25, n=10-30, R1 represents Me, Ph or C2-C8 aromatic hydrocarbon or alkane, R2 represents Me or H, and Y represents a group containing C-C unsaturated bond. The preparation method of the poly(methylsilane-carbosilane) comprises the following steps of: in an organic solvent, carrying out a Wurtz type condensation polymerization reaction on a chlorosilane monomer mixture and insufficient alkali metal to synthesize Si-Cl bond-containing intermediate polymer; and then obtaining liquid methylsilane-carbosilane copolymer containing a C-C unsaturated bond through a grignard coupling reaction. The poly(methylsilane-carbosilane) disclosed by the invention can be served as a silicon carbide ceramic precursor, has the advantages of high ceramic yield, good storage stability and adjustability in structure composition, and can be applied to precursors of ceramic coatings and block body materials, and impregnants of composite materials.

The invention relates to in-situ ceramization type anti-oxidant resin, resin matrix and ceramic material, as well as a preparation method of the resin. Carborane and silazane serve as raw materials, a solvent is not used in the preparation process, Diels-Alder addition reaction and cross-linking solidification are conducted through vinyl under the action of an initiator, the raw materials and the vinyl perform hydrosilylation reaction when the raw materials contain a Si-H group, and the two kinds of reaction form a compact three-dimensional space network structure, so that the resin has excellent heat resistance; micromolecular byproducts in the condensation polymerization process are avoided by utilizing vinyl addition and hydrosilylation reaction; in addition, the resin system has high oxidation resistance, can be subjected to in-situ ceramization under the action of high temperature, is high in ceramic yield, and can serve as a resin matrix or a ceramic precursor of a heat-resistant composite material to be applied to the fields of national defense, aviation, spaceflight and the like.

The invention relates to the technical field of continuous fiber reinforced ceramic matrix composite materials, and particularly discloses a three-dimensional aluminum oxide fiber woven part reinforced aluminum oxide composite material based on an aqueous slurry impregnation process, and the porosity of the composite material is 20-30%. A reinforced phase of the composite material is a continuous aluminum oxide fiber woven part, the woven part is in a fiber cloth sewing, two-dimensional and half or three-dimensional weaving mode, the mass content of alumina in alumina fibers is not lower than 70%, and the volume fraction of the fibers in the composite material is 40-45%. The aluminum oxide matrix of the composite material is prepared through the processes of multiple times of dipping, drying and sintering of water-based aluminum oxide powder slurry with high solid content and low viscosity, the solid content of the water-based aluminum oxide powder slurry is 30-40 vol%, the viscosity of the slurry is 5-30 mPas, the pH is 3-4.5, and the Zeta potential is 60-70 mV. The invention also provides a preparation method of the composite material. The reinforced fibers are arranged between the layers of the composite material, so that the integrity is good. The preparation method disclosed by the invention is simple in process, low in cost, good in environmental protection property and easy to realize large-scale industrialization.

The invention provides a preparation method for liquid hyperbranched polycarbosilane containing an acryloyloxy group. The liquid hyperbranched polycarbosilane containing the acryloyloxy group is prepared from liquid hyperbranched polycarbosilane containing a Si-H bond and an acryloyloxy compound containing a hydroxyl or mercapto group through a reaction without a catalyst or under the catalysis of halide of metallic Zn, Al, B, Sn, Cr, Co or Pd, oxide of alkali metal, hydroxide of alkali metal or organic base. The preparation method is simple and the content of the acryloyloxy group in the product can be controlled, so the ceramic yield of the product is improved.

The invention discloses molybdenum disilicide / silicon carbide three-dimensional polymer precursor ceramic and a preparation method thereof, belonging to preparation of ceramic materials. The preparation method comprises the following steps: putting precursor PVG powder into a graphite paper boat and carrying out high-temperature cracking under the protection of an inert atmosphere; mixing MoSi2, cracked SiC(rGO)p ceramic particles and the precursor PVG powder to form a MoSi2 / SiC(rGO)p / PVG mixture, carrying out ball milling and uniform mixing in an alcohol medium, and then drying the MoSi2 / SiC(rGO)p / PVG mixture in an oven; and loading the mixture into a mold for compression molding, conducing demolding to obtain a biscuit, putting the biscuit into an inert atmosphere tube furnace for high-temperature sintering, and conducting cooling along with the furnace to obtain black molybdenum disilicide / silicon carbide three-dimensional polymer precursor ceramic, namely 3D-SiC(rGO, MoSi2x) nanometer composite block ceramic for short, wherein x is the mass fraction of silicon carbide in the whole biscuit. The obtained ceramic is high in heat conductivity and electric conductivity and good in formability and component uniformity; and the preparation method is simple and economical in process.

This invention provides a method for preparing a polycarbosilane by decomposition and rearrangement a cyclic silane compound or chain polysilane under the catalysis of a boron-containing catalyst in a trace amount (less than 1 wt %). In the method, poly(dimethylsilane) (denoted as PDMS) or a thermal decomposition product thereof, i.e., a liquid silane-carbosilane compound (denoted as LPS), is used as the raw material, less than 1 wt % of the boron-containing catalyst (with respect to the amount of the raw material) is added, and then the temperature is gradually increased to the reaction temperature under atmospheric pressure or high pressure to perform the thermal decomposition / rearrangement reaction so as to obtain solid polycarbosilane (PCS) with a higher ceramic yield. This method has advantages, such as short reaction time, high synthetic yield, good product quality, simple equipment and safe operation; and the polycarbosilane prepared is a polymeric precursor for SiC, and can be used for the preparation of SiC fibers and SiC-based composite materials.

The invention provides an environmental barrier coating. The environmental barrier coating is composed of a SiC bonding layer, a mullite middle layer and an ytterbium silicate outer coating, which coat a C / SiC composite material and are sequentially arranged from inside to outside. The C / SiC composite material coated by a SiC coating is prepared by a secondary chemical vapor deposition (CVD) method; the mullite middle layer is prepared by combining a sol-gel method with an air spraying technology, and the ytterbium silicate outer coating is prepared by combining a solid phase sintering technology with an air spraying technology. Through a smart EBC coating system and a preparation process, the ytterbium silicate outer coating is prepared by combining a solid phase sintering technology withan air spraying technology for the first time, the mullite middle layer and the ytterbium silicate outer coating are tightly combined, and the coating is compact and free of cracks. The traditional sol-gel process is improved to a great extent, the defects of cracking, peeling and poor binding force in the sintering process of a coating prepared through a traditional sol-gel method are maximallyovercome, and the use requirements of large components and special-shaped parts can be met.

The invention belongs to the technical field of coating materials, and provides a preparation method of a high-temperature-resistant coating for a ceramic-based composite material. According to the invention, tetraethoxysilane and N,N-dimethylformamide are respectively used as an anti-gelling agent and a dispersing agent, and the coating is obtained on the surface of the ceramic-based composite material by adopting a process consisting of dipping, mould pressing low-temperature gelatinization and high-temperature cracking. The preparation method is short in preparation period and low in cost;the temperature of mold pressing low-temperature gelatinization and high-temperature cracking is lower than 1000 DEG C, so influence on the ceramic-based composite material is small; the strength retention rate of the material obtained after the obtained coating is oxidized at 1500 DEG C for 1 h is larger than or equal to 60%, so good high-temperature resistance is achieved; the coating is good inconsistency, has high binding force (larger than or equal to 10 MPa) with a matrix, presents good compactness and integrity and can be applied to the field of aerospace.

The invention discloses a preparation method for a high-temperature-resistant ceramic precursor adhesive. The preparation method comprises the following steps of (1) adding metal sodium and methylbenzene into a three-opening flask with a condensation backflow device and a mechanical stirring device, heating to 80-120 DEG C under the protection of inert atmosphere, dropping methyl dichloresilane, preserving the heat of 80-140 DEG C for 2-4 hours after dropping is finished, and filtering and distilling to remove an organic solvent to obtain liquid polymethylsilane; (2) mixing liquid polymethylsilane and tetramethyldivinyldisilazane according to a mass ratio of 1:(1 to 10), preserving the heat of 100-250 DEG C for 1-10 hours under the protection of inert atmosphere, and obtaining a liquid polymethylsilane precursor; (3) respectively adding a micron-level inorganic filler and a nano-level inorganic filler into the liquid polymethylsilane precursor, and uniformly mixing to obtain the high-temperature-resistant ceramic precursor adhesive. The ceramic precursor adhesive is high in bonding strength and excellent in heat resistance, and has a wide application prospect in adhering of ceramic materials and carbon materials.