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2407 results about "Alumina ceramic" patented technology

Alumina ceramic is the most mature of the engineering ceramics, offering excellent electrical insulation properties together with high hardness and good wear resistance but relatively low strength and fracture toughness. Alumina Ceramics are generally white but may also be pink (88% alumina), or brown (96% Alumina).

High temperature, oxidation-resistant abradable coatings containing microballoons and method for applying same

An abradable coating composition for use on shrouds in gas turbine engines or other hot gas path metal components exposed to high temperatures containing an initial porous coating phase created by adding an amount of inorganic microspheres, preferably alumina-ceramic microballoons, to a base metal alloy containing high Al, Cr or Ti such as β-NiAl or, alternatively, MCrAlY that serves to increase the brittle nature of the metal matrix, thereby increasing the abradability and oxidation resistance of the coating at elevated temperatures. Coatings having a total open and closed porosity of between 20% and 55% by volume due to the presence of ceramic microballoons ranging in size from about 10 microns to about 200 microns have been found to exhibit excellent abradability for applications involving turbine shroud coatings. An abradable coating thickness in the range of between 40 and 60 ml provides improved performance for turbine shrouds exposed to gas temperatures between 1380° F. and 1800° F. Abradable coatings in accordance with the invention can be used for new metal components or to repair existing equipment. The coatings can be applied to the metal shroud using thermal spray, processes that integrate sintering and brazing, or direct write techniques.
Owner:GENERAL ELECTRIC CO

Armor of ceramic-metal composite and preparation method thereof

The invention discloses a metallic/ceramic composite armor and preparation method with ordered supporting structure of metallic materials as a framework and alumina ceramic materials as a core, and comprises the following steps: (1) a ceramic core plate with well-ordered pore canals is prepared and comprises working procedures such as forming, first sintering, hole machining and final sintering; (2) the ceramic core plate is sintered and metallized, all the surfaces of the finally sintered ceramic core plate is coated with Mo-Mn metal pastes, after being dried, the finally sintered ceramic core plate is metallized and sintered by being put under a protective atmosphere; (3) the metal is poured or vacuum heating treatment is made, the metal material is heated into a molten state, then poured into a die in which the ceramic core plate is arranged to have a thermostatic treatment, and finally cooled slowly to knock out. The invention can overcome weak binding of articulated connection and plane connection between the metal and the ceramic, etc., and realize high-strength binding between metallic/ceramic interfaces, moreover, the prepared metallic/ceramic composite armor with the sandwiches which can pass mutually is provided with the performance of light weight, high strength and impact resistance, thereby being suitable for a bulletproof composite armor plate and an armored panel on tanks and armored vehicles, etc.
Owner:XI AN JIAOTONG UNIV

Solar selective absorbing coating and preparation method thereof

The invention discloses a solar selective absorbing coating and a preparation method thereof. The coating comprises three layers of films from bottom to top on the surface of a heat absorber substrate; the first layer is an infrared reflective layer and consists of a metal molybdenum film; the second layer is an absorption layer, consists of a composite metal ceramic layer made from Ni-Al alloy particles and an insulating medium and is formed by two sublayers with different thicknesses and different Ni-Al alloy volume percentages in structure, wherein the thickness of the first sublayer is 35-70nm, the Ni-Al alloy volume percentage of the first sublayer is 40-60 percent, the thickness of the second sublayer is 30-60nm, and the Ni-Al alloy volume percentage of the second sublayer is 20-40 percent; the third layer is an anti-reflection layer formed by an aluminum oxide ceramic film. The preparation method thereof comprises three steps. Under the condition that an air quality factor AM is 1.5, the absorptivity of the coating is no less than 0.93, and the emissivity of the coating is no more than 0.09. The coating has good heat stability and can be used in the vacuum environment at the temperature of 600 DEG C for a long term. The invention has the practical value and wide application prospect in the technical field of solar heat utilization and thermal generation.
Owner:安徽科鑫光热技术有限公司

Fine-crystal transparent alumina ceramic of high straight-line luminous transmittance and method for preparing same

The invention discloses high-linear light transmittance fine crystalline transparent alumina ceramics and a method for making the same under the condition of a pulse electric field. The transparent alumina ceramics is sintered within a temperature range of between 1,050 and 1,400 DEG C with the time of the entire sintering process less than 30 minutes; moreover, the material has a relative density higher than 99.5 percent, average grain size of between 0.3 and 1 micron, Vickers hardness more than 20GPa, bending strength of between 700 and 900 MPa, fracture toughness of between 3 and 4 MPam<1/2> and linear light transmittance more than 50 percent; and the linear light transmittance of a better material can reach to more than 62 percent. The transparent alumina ceramics can be pure alumina with the purity more than 99.99 percent, or can be alumina ceramics in which one sort, or any two sorts, or any three sorts of addition agents including 0.01 to 0.5 percent of MgO, 0.01 to 0.5 percent of Y2O3, 0.01 to 0.5 percent of La2O3 and 0.01 to 0.5 percent of ZrO2 are added. The method for making the transparent alumina ceramics has the characteristics of low temperature and quickness; moreover, the technology has high reliability, and the deviation between the mechanical property and the optical performance of transparent alumina made in different batches is not more than 2 percent.
Owner:王昕

Preparation method for self-complement sub-micron crystal alumina ceramic

ActiveCN101343176APrecisely control the sintering regimeHigh hardnessSilicon oxideSlurry
The invention relates to a preparation method of a low-cost self-reinforced submicron grain alumina ceramic, which belongs to the fine ceramic field. The method comprises the steps of: adopting industrial aluminum hydroxide or boehmite as a raw material, adding fine grain Alpha-alumina and water for ball milling so as to obtain an even slurry; adding water for mixing at a temperature between 70 and 90 DEG C, and adding acid to control the pH value at 2 to 5, so as to form an emulsion; and adding an additive which is a mixture selected from one or more than two of zinc oxide, magnesium oxide, calcium oxide, yttrium oxide, lanthanum oxide, zirconium oxide, boric oxide, ferric oxide, vanadium oxide, silicon oxide or titanium oxide for forming a gel after water is evaporated, and drying the gel and then sintering the gel under high temperature for preparing the self-reinforced submicron grain alumina ceramic containing alumina elongated grains. The ceramic is characterized in that crystal grains have diameters of less than 0.5mu m, and a microstructure contains elongated alumina grains have length-diameter ratios of larger than 5, and has the advantages of high hardness, high toughness and good wear resistance, and can be widely used in ceramic grinding media and the abrasives industry.
Owner:SUZHOU CHUANGYUAN INVESTMENT DEV

Preparation method of continuous alumina fiber-reinforced aluminum oxide ceramic matrix composite material

The invention belongs to a continuous alumina fiber-reinforced aluminum oxide ceramic matrix composite material preparation technology and relates to a preparation method of a continuous alumina fiber-reinforced aluminum oxide ceramic matrix composite material. Firstly, an oxide organic polymer precursor is adopted as a raw material, a porous oxide ceramic coating is prepared through PIP process to serve as a fiber and matrix interface in the composite material, then a freeze drying process of aluminum oxide ceramic slurry is utilized to obtain a porous aluminum oxide matrix green body framework provided with three-dimensional network through holes, the oxide organic polymer precursor is utilized to repeatedly dip the porous aluminum oxide matrix green body framework to obtain a dense matrix green body, and finally the composite material green body is sintered to obtain the high-performance composite material. The freeze drying process is adopted in the matrix compactness process so that the high compactness matrix can be obtained, it can be also ensured that the interlayer layer does not crack before high-temperature heat treatment, obtaining of the porous oxide coating is ensured, so that a weak interface is formed between the fiber and the matrix of the composite material, and a toughness improving effect of the composite material is achieved.
Owner:AVIC COMPOSITES

Machinable aluminium oxide ceramics and preparation method of machinable aluminium oxide ceramics

The invention discloses machinable aluminium oxide ceramics which is characterized in that the machinable aluminium oxide ceramics comprises the following components in percentage by mass: 60 percent to 68 percent of nano alumina, 30 percent to 36 percent of tabular alumina, 0.5 percent to 1.5 percent of magnesium oxide and 1 percent to 3 percent of titanium dioxide. A preparation method of the ceramics comprises the following steps of: preparing the nano alumina; after carrying out mixing and ball milling on the nano alumina, alumina, the magnesium oxide, titanium dioxide and absolute ethyl alcohol, drying the mixture, removing zirconium oxide grinding balls, and carrying out roasting, washing, filtering and drying on the obtained product to obtain composite powder; and after uniformly mixing the composite powder and a polyvinyl alcohol 1799 binder and pelleting the obtained mixture, carrying out dry-pressing forming to obtain a green body and placing the formed green body into a high temperature furnace to carry out sintering so as to obtain the ceramics. The bending strength of the ceramics reaches 526MPa. The fracture toughness of the ceramics reaches 6.4MPa.m1 / 2. The ceramicshave excellent machinable performance. The problems of complex structure and high cost and difficultly-controlled preparation process of the existing machinable ceramics are effectively solved.
Owner:SOUTHWEAT UNIV OF SCI & TECH

Integrated chip type oxygen sensor and manufacturing method thereof

The invention relates to the technical field of integrated chips used for zirconium oxide sensors, in particular to an integrated chip type oxygen sensor and a manufacturing method thereof. The integrated chip type oxygen sensor comprises a zirconium oxide substrate, wherein the zirconium oxide substrate consists of an upper layer of zirconium oxide substrate and a lower layer of zirconium oxide substrate; an external surface of the upper layer of zirconium oxide substrate is provided with a measuring electrode, and an internal surface of the upper layer of zirconium oxide substrate is provided with a reference electrode and a long and narrow gap; an internal surface of the lower layer of zirconium oxide substrate directly contacts the long and narrow gap, and an alumina ceramic insulating layer is coated on an external surface of the lower layer of zirconium oxide substrate; the alumina ceramic insulating layer is directly integrated with a platinum heating element; a heating electrode plate and the platinum heating element are directly connected together on the external surface of the zirconium oxide substrate; and the outermost layer of the zirconium oxide substrate is provided with a porous ceramic protective layer. The integrated chip type oxygen sensor provided by the invention is only provided with two layers of zirconium oxide substrates and integrated with the heating elements, and has the advantages of thin thickness, and simple preparation method, high production efficiency and high stability.
Owner:CHANGZHOU LAMBDA ELECTRONICS

Alumina ceramic and preparation method thereof

ActiveCN101117284AAvoid the debinding processSimple processTunnel kilnCelsius Degree
The invention provides alumina ceramics and a manufacturing method of the alumina ceramics. The main materials of the alumina ceramics are as follows: alumina micro mist or a superfine alumina micro mist which is formed by Gamma alumina and an Alpha alumina with an particle diameter of between zero point one to three point five micron and a purity of ninety-nine point nine percent or more than ninety-nine point nine percent according to certain proportion. One or a mixture of a small quantity of magnesia, yttria, lanthana, thulia and yttria stabilized zirconia is added into the micro mist as sinter accessory ingredient and is subject to dry pressing, grouting and isostatic cool pressing after being even mixed evenly, thus ceram green pressing is obtained. Only a little organic addition agent is needed to be added. After drying, the green pressing body does not need to be roasted and can be directly introduced to an ordinary high temperature si-mo rod resistance furnace or a continuous type si-mo rod electrothermal tunnel kiln to be sintered for one to three hours at a temperature below one thousand six hundred and seventy Celsius system. Therefore, the alumina ceramics can be obtained with high tightness, mechanical property and good dielectric property and with a nonconventional structure and a placode the size of which is zero point two to two hundred millimeter and a purity of ninety nine to ninety-nine point nine percent.
Owner:BEIJING SINOMA SYNTHETIC CRYSTALS CO LTD +1
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