93 results about "Alumina matrix" patented technology

Method for producing zirconia-reinforced Al₂O₃ grains, including at least the following steps: inductively melting a starting mixture to form a eutectic melt made of alumina and zirconia; applying the eutectic melt as a thin layer material, the thin layer material being quenched; and removing the thin layer material. In this manner abrasive grains can be formed directly or the thin layer material can be classified when it is broken into abrasive grains, the grains are polycrystalline without amorphous glass phases as an alumina matrix having zirconia precipitations, and at least some of the zirconia precipitations can be formed in the nanoscale range.

An alkylating process for the production of at least one of 2-, 3-, 4-, 5-, and 6-phenylalkanes by alkylation of an aromatic compound with a feedstock containing at least one olefin comprising at least 9 carbon atoms per molecule, in the presence of a catalyst comprising at least one substrate based on at least a zeolite and a non-zeolitic silica-alumina matrix with a low content of macropores, whereby said matrix contains an amount of more than 5% by weight and less than or equal to 95% by weight of silica (SiO₂), whereby said process is carried out at a temperature of between 30 and 400° C., a pressure of between 0.1 and 10 MPa, an hourly volumetric flow rate of 0.50 to 200 h⁻¹, and an aromatic compound/olefin molar ratio of between 1:1 and 50:1.

A material (100) formed of a sintered aggregation of ceria particles (106), mullite particles (108) and an alumina matrix material (110). Differential thermal expansion of the ceria and mullite particles generates thermal stress sufficient to create micro-cracking of the ceria particles. The ratio of ceria to mullite may be selected to achieve a desired coefficient of thermal expansion for matching the thermal growth of a mating CMC material (102). The micro cracks provide the material with a desired degree of strain tolerance useful in high temperature applications such as a solid core gas turbine vane (20).

The invention relates to a method for preparing a closed-pore porous heat-insulating alumina ceramic. According to the method, a powder which is prepared by adopting a hydrothermal synthesis method and is in a core-shell structure is added into alumina slurry as a pore forming agent to prepare an alumina ceramic, in the process of sintering an alumina ceramic blank, the carbon sphere as a core is removed under oxidization, the alumina layer as a shell and the alumina substrate are sintered compactly to form a magnesium-aluminium spinel together with a sintering additive, and the magnesium-aluminium spinel is pined into the grain boundary. Closed pores are introduced into the prepared alumina ceramic successfully, the rate of closed pores of the alumina ceramic is up to10-60%, and the rate of open pores is less than 5%. The thermal conductivity of the alumina ceramic is 0.1W/(m.K), and the usage temperature is over 1,400 DEG C. The method provided by the invention can be used for overcoming the defects that the existing process for preparing the porous ceramic by foaming is complex, too many additives are added, and the product is easy to powderize.

The invention provides a self-reaction alumina-based composite ceramic core for precision casting, and a preparation method thereof. The composite ceramic core consists of alundum powder, in-situ synthesized aluminum titanate, MgTi2O5 and mullite. The composite ceramic core is prepared from the following raw materials in weight percentage: 70 to 85 percent of alundum powder with different particle sizes, 0 to 2 percent of magnesium oxide powder, 8 to 20 percent of titanium dioxide powder and 6 to 10 percent of kyanite powder, and carbon powder accounting for 1 to 3 percent of the gross mass of the four raw materials is added as an easy-breakdown agent. The method prepares the composite ceramic core through the following steps of mixing, dry-pressing, shaping and firing the raw materials at high temperature. As other raw materials are added to an alumina matrix of the invention, the prepared composite ceramic core has the advantages of good high-temperature chemical stability and thermal stability, low thermal expansion coefficient and small shrinkage factor after sintering, and meets the requirements of a ceramic core for precision casting on room temperature and high temperature strength.

Disclosed are alumina particles with a dispersed noble metal. The alumina particles are hollow-structured alumina particles which comprise alumina as a major component of the matrix, and in which at least one noble metal is dispersed in the alumina matrix and/or on the surface of the alumina particles with a dispersion degree of 10% or more when being measured by the CO adsorption method. The noble metal dispersion degree is so high that the alumina particles are suitable for making a catalyst. The resulting catalyst exhibits the purifying performance, which hardly differs before and after a high temperature durability test, and is extremely good in terms of the durability.

A ceramic cutting tool including a ceramic base member 4 of a tool main body 1 which is formed of a composite ceramic which contains a hard phase dispersed within an alumina matrix phase. The hard phase contains, as a predominant component, one or more elements selected from hard-phase-forming metal elements M in the form of at least one of a carbide, nitride, or boride, or in the form of a solid solution of at least two selected from the carbide, nitride and boride. The hard-phase-forming metal elements M include Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si. The surface of the ceramic base member 4 is covered with a coating layer 1f, which contains titanium carbonitride or titanium nitride as a predominant component. The coating layer 1f has an average crystal-grain size of 0.1 to 0.5 μm as observed on the surface, and an average thickness of 0.5 to 2 μm. The coating layer 4f is formed by a CVD at a low to medium temperature range of 750 to 900° C. The ceramic cutting tool can be fabricated at low cost and can secure stable cutting performance over a long period even when the tool is used under severe cutting conditions under which large thermal and mechanical loads act on the tool.

The invention discloses a method for manufacturing transparent alumina ceramic, which belongs to the technical field of high-performance transparent alumina ceramic preparation. In the method, an additive is introduced by adopting a chemical heterogeneous nucleation sedimentation method, so that the additive ions are uniformly coated on the surface of alumina powder by using the alumina powder asa heterogeneous nucleation center to form nano powder with 'shell-nuclear' composite structure; and the obtained nano powder is molded and sintered to prepare the transparent alumina ceramic. The additive is coated on the surface of the alumina powder to form a nano coating, and the additive is finally uniformly dispersed in the alumina matrix on nano scale after sintering so as to achieve the effect of well inhibiting the growth of crystal grains. The method successfully overcomes the defect caused by a wet mixing ball milling method, and finally prepares the transparent alumina ceramic withfiner and more uniform additive microstructure and better light transmission. The linear transmittance of the prepared transparent alumina ceramic is about 35 to 43 percent when the wavelength is 300to 800 nanometers.

The invention discloses a carbon nano tube-aluminium oxide composite material. The composite material consists of carbon nano tubes and aluminium oxide, wherein the content of the carbon nano tubes in weight percent is 0.1%-6%. The composite material is prepared by virtue of a hot-pressing sintering technology and the carbon nano tubes are uniformly dispersed in an aluminium oxide matrix material. By hot-pressing sintering, the problem about the compacting sintering of the composite material can be solved; besides, the sintering temperature is lowered remarkably and the sintering time is prolonged. The compactness of the composite material reaches 98.8%, and the fracture toughness of the composite material reaches 6.32MPam1/2 which is improved by about 99.2% compared with that of the aluminium oxide material. XRD (X Ray Diffraction) and SEM (Scanning Electron Microscope) results show that under the hot-pressing sintering condition, the composite material forms an intact sintered phase and is high in compactness, transgranular fractures are interlaced with intergranular fractures on the matrix, the carbon nano tubes are uniformly dispersed in the aluminium oxide matrix and no agglomeration phenomenon happen.

The invention relates to a lanthanum oxide and aluminum oxide composite coating layer which are prepared by adopting a plasma spraying method and the preparation method thereof, which belongs to the abrasion proof ceramic coating layer field. Aluminum oxide power and lanthanum oxide power are weighed as per the 3/97 to 10/90 proportion of lanthanum oxide and aluminum oxide and then are mixed by ball milling; composite power is deposited on the cleaned and blasted metal basis material by adopting the plasma spraying process. The microstructure analysis of the lanthanum oxide and aluminum oxide composite coating layer prepared by the invention shows that the lanthanum element is uniformly dispersed on the basal body of the aluminum oxide, compared with the spraying pure Al2O3 coating layer, a plasma spraying Al2O3-La2O3 coating layer has higher deposition efficiency, and the wear resistant of the plasma spraying coating layer is effectively improved.

The invention relates to a self-toughening substance containing type continuous fiber reinforced thermo-structure composite and a preparation method thereof. The self-toughening substance containing type continuous fiber reinforced thermo-structure composite comprises a substrate which consists of a porous mullite framework and an aluminum oxide substrate, and a reinforcement which is a three-dimensional continuous aluminum oxide fiber fabric, wherein the porous mullite framework is prepared from mullite powder which is converted through mullite sol; the aluminum oxide substrate is prepared according to an infiltration pyrolysis method using Al2Cl(OH)5 as a precursor. The self-toughening substance containing type continuous fiber reinforced thermo-structure composite is outstanding in mechanical property, high in bending intensity, high in high-temperature stability, and of great significance on the development of the technical field.

The catalyst for reducing olefin content in mixed material of liquefied gas and gasoline includes cocrystallized RE-ZSM5/ZSM11 molecular sieve as the active component in 25-75 wt% and alumina matrix for the rest. Its preparation process includes the following steps: 1. adding the aluminum source, inorganic acid, RE salt, water glass and deionized water successively into the reactor under stirring to synthesize the active component cocrystallized RE-ZSM5/ZSM11 molecular sieve; and 2. mixing the cocrystallized RE-ZSM5/ZSM11 molecular sieve with alumina and water, extruding the mixture into strip, drying at 60-120 deg.c for 2-4 hr, roasting in air atmosphere at 500-600 deg.c for 4-6 hr, and curing in 100 % water vapor at 400-600 deg.c for 2-10 hr to obtain the catalyst. The catalyst of the present invention has the capacity of obviously lowering olefin content in mixed material of liquefied gas and gasoline and raising the arene content.

An aluminium-wettable protective coating on a substrate, for use at elevated temperature in an oxidising and/or corrosive gaseous and/or molten environment is disclosed. The coating (20A, 20B, 20C, 20D) is applied to protect the substrate (5, 15, 16) from liquid and/or gaseous attack. The coating comprises particles of at least one metal oxide and/or at least one partly oxidised metal in a dried and/or cured colloidal carrier and/or organic binder. The metal oxide and/or partly oxide metal is reactable with molten aluminium when exposed thereto to form an alumina matrix containing metal of said particles and aluminium. The coated substrate (5, 15, 16) may be used in an aluminium electrowinning cell an arc furnace for the recycling of steel or an apparatus for the purification of a molten metal such as aluminium, magnesium, iron or steel.

The invention discloses a chip type oxygen sensor, which has high heating efficiency, fast response speed and higher strength. The chip type oxygen sensor comprises three parts, namely, a ceramic heater (1), an alumina substrate (2) and a zirconium oxide substrate (3), which are sequentially arrange from bottom to top; a reference air channel (21) is arrange on the alumina substrate; an inner working electrode (31) and an inner working electrode (32) are pasted on the upper surface and lower surface of the zirconium oxide substrate (3) respectively; the outer working electrode (32) is printed with a porous protective layer (33); an alumina printing layer (4) and a zirconium oxide printing layer (5) are printed between the alumina substrate (2) and the zirconium oxide substrate (3); the alumina printing layer (4) is printed on the upper side surface of the alumina substrate (2); and the zirconium oxide printing layer (5) is printed on the lower side surface of the zirconium oxide substrate (3). The chip type oxygen sensor can be applied in the technical field of automobile engine exhaust testing.

A method of forming a structurally integrated component. The method comprises providing a first ceramic material comprising an oxidation sensitive ceramic material and providing a second ceramic material comprising an uncured, oxide ceramic matrix composite. The first ceramic material may be a carbon-based ceramic material selected from the group consisting of carbon fibers, carbon whiskers, carbon powder, graphite, silicon carbide, silicon oxycarbide, and mixtures thereof. The second ceramic material may comprise an inorganic oxide fiber reinforcement impregnated with an alumina matrix or an aluminosilicate matrix. The second ceramic material and the first ceramic material are contacted to form an uncured, structurally integrated precursor component, which is co-cured. The co-cured, structurally integrated precursor component is then co-fired in an inert atmosphere to bond the first ceramic material and the second ceramic material. A co-cured, structurally integrated precursor component and a structurally integrated component are also disclosed.

The invention relates to the field of composite materials for bulletproof armor, in particular to a silicon carbide whisker-toughened aluminum oxide composite ceramic material for bulletproof armor and a preparation method thereof. The composite ceramic material is composed of silicon carbide whiskers with a volume fraction of 5%-80% and aluminum oxide. Microscopically, the silicon carbide whiskers are preferentially arranged in an aluminum oxide matrix along a group of parallel planes. The preparation method of the composite ceramic material comprises the following steps: carrying out freezecasting and vacuum freeze drying treatment on water-based slurry containing the silicon carbide whiskers and the aluminum oxide powder to obtain a porous green body with an oriented lamellar structure, and sequentially carrying out pressure forming, organic matter removal and sintering densification treatment on the green body to obtain the aluminum oxide composite ceramic material toughened by the silicon carbide whiskers. The fracture toughness, impact toughness and repeated impact resistance of the composite ceramic material are remarkably improved compared with single silicon carbide ceramic and single aluminum oxide ceramic; and the composite ceramic material is expected to be applied to the field of bulletproof armor to effectively improve the protection capacity and durability of the bulletproof armor.

The present invention is a kind of catalyst containing MCM-22 zeolite 30-90 wt%, halogen counting in simple substance 0.1-2 wt% and alumina matrix in the balanced amount. The catalyst is used in liquid phase benzene alkylating reaction, and compared with available technology, the catalyst has raised ethyl benzene selectivity, lowered diethyl benzene and triethyl benzene selectivity, and 7.3-10.0 % raised ethyl benzene STY.

The invention discloses a single crystal alumina low-temperature brazing method, and belongs to the technical field of ceramic material connection. According to the method, low-temperature brazing connection of single crystal alumina is achieved through the characteristics that the melting point of tin is low and activity of titanium is high, and thermal damage during the brazing process is reduced; and thermal stress generated during the brazing process is effectively released through the characteristic that tin is soft, and residual stress of interface connection parts of single crystal alumina and brazing filler metal is reduced. The method is achieved through the following steps of: firstly preparing Sn-Ag-Cu-Ti alloy powder; carrying out ultrasonic cleaning on a single crystal aluminamatrix through acetone, and drying the single crystal alumina matrix; then, spraying the Sn-Ag-Cu-Ti alloy powder on the surface of the polished single crystal alumina matrix; then, placing another polished single crystal alumina matrix on the alloy powder; and finally, putting the entire single crystal alumina/brazing filler metal/single crystal alumina sandwich structure into a quartz tube, carrying out vacuumizing till the vacuum degree is 5* 10 (<->4) Pa or below, moving the quartz tube into a tube furnace, heating for 30 min at the temperature of 450 DEG C to 650 DEG C, taking out the quartz tube in a vacuumized state, and cooling the quartz tube to the room temperature.

This invention discloses a new type of large area electronic field emission nano-structured array and its preparation method, in which, the structure includes: Alumina nano-conical cones of pinpoint structure are distributed uniformly on a matrix vertically and are coated with a layer of electronic field emission material and holes of the matrix are filled with conductive electrode materials. The preparation method includes: carrying out electrochemical anode oxidation process to an Al foil or Al adhered on the matrix to get a matrix with Almina film and nm holes at the surface, corroding the film with a corroding solution reacting with Almina to get the large area serial Almina nm conical array, filling the holes of the matrix with conductive electrode material and then coaring a layer of field emission material on the array to get a new type of large area electronic field emission nm-structured array.

The invention discloses a preparation method of an oriented graphene/alumina composite ceramic. The method comprises the following steps: 1, preparing alumina monohydrate/graphene composite sponge; and 2, preparing an oriented graphene/alumina composite material. According to the method disclosed by the invention, water-soluble alumina monohydrate is introduced into an alumina ceramic phase, and orientation of graphene in an alumina matrix is realized by oriented freezing and oriented pressurizing in hot pressed sintering, so that a shell-like structure is obtained. The structure is capable ofendowing alumina ceramics with excellent breaking tenacity, bending strength and other mechanical properties, and enabling the alumina ceramics to achieve excellent electrical and thermal conductivity and obvious electrical and thermal anisotropic properties in an oriented direction. The process is simple, the cost is low, and an excellent alumina ceramic-based composite material with integrationof structure and function can be obtained.