Abstract:
The present invention concerns a method of producing an ultrahard abrasive composite material having a desirable overall thermal expansion coefficient mismatch, between the ultrahard particles and their matrix materials. The method includes the steps of providing a volume fraction of ultrahard particles having a pre-determined thermal expansion coefficient; determining the volume fraction and thermal expansion coefficient of a matrix material that would be required to produce an ultrahard composite material having a desired overall thermal expansion coefficient mismatch; contacting the ultrahard particles and the matrix material to form a reaction volume; and consolidating and sintering the reaction volume at a pressure and a temperature at which the ultrahard particles are crystallographically or thermodynamically stable. Ultrahard composites where the ultrahard particles are cubic boron nitride and/or diamond are provided, with matrix materials chosen to produce thermal expansion mismatches within specific value ranges, and associated, controlled residual stresses. Ultrahard composite matrices involving combinations of nitride matrices such as titanium nitride/tantalum nitride, and titanium nitride/ chromium nitride are exemplified.
Abstract:
Calcium-phosphate nanofiber matrices comprising randomly dispersed crystalline calcium-phosphate nanofibers are provided. The nanofibers are synthesized using sol-gel methods combined with electrospinning. The nanofibers may be hollow, solid or may comprise a calcium-phosphate shell surrounding a polymer containing inner core to which biologically functional additives may be added. The nanofiber matrices may be used to culture bone and dental cells, and as implants to treat bone, dental or periodontal diseases and defects.
Abstract:
A method of manufacturing polycrystalline abrasive elements consisting of micron, sub-micron or nano-sized ultrahard abrasives dispersed in micron, sub-micron or nano-sized matrix materials. A plurality of ultrahard abrasive particles having vitreophilic surfaces are coated with a matrix precursor material in a refined colloidal process and then treated to render them suitable for sintering. The matrix precursor material can be converted to an oxide, nitride, carbide, oxynitride, oxycarbide, or carbonitride, or an elemental form thereof. The coated ultrahard abrasive particles are consolidated and sintered at a pressure and temperature at which they are crystallographically or thermodynamically stable.
Abstract:
A dielectric ceramic composition in a multilayer ceramic capacitor having a composition of formula: {[(CaO) t (SrO) 1-t ] w [(Zr0 2 ) v (Ti0 2 ) 1-v ]} 1-s-x.y-z A s E x G y H z wherein: {[(CaO) t (SrO) 1-t ] w [(ZrO 2 ) v (TiO 2 ) 1-v ]}as a first component; and A s E x G y H z as a second component; wherein A is a transition metal oxide; E is an oxide of an element selected from group III, group IV, and mixtures thereof; G is an oxide of a group II element; H is an oxide of an element selected from Y, a lanthanide, and mixtures thereof; w is 0.95 to 1.05; t is 0.50 to 1.0; v is 0.8 to 1.0; s is 0.0001 to 0.08; x is 0 to 0.08; y is 0 to 0.20; z is 0 to 0.20; and wherein said second component is homogeneously coated in solution form on said first component without multidentate chelates.In the method of example 1, the particles are coated with a V. blender.
Abstract:
Graphitic structures have been prepared by exposing templates (metal, metal-coated ceramic, graphite, for example) to a gaseous mixture that includes hydrocarbons and oxygen. When the template is metal, subsequent acid treatment removes the metal to yield monoliths, hollow graphitic structures, and other products. The shapes of the coated and hollow graphitic structures mimic the shapes of the templates.
Abstract:
A method of manufacturing polycrystalline abrasive elements consisting of micron, sub-micron or nano-sized ultrahard abrasives dispersed in micron, sub-micron or nano-sized matrix materials. A plurality of ultrahard abrasive particles having vitreophilic surfaces are coated with a matrix precursor material and then treated to render them suitable for sintering. The matrix precursor material can be converted to an oxide, nitride, carbide, oxynitride, oxycarbide, or carbonitride, or an elemental form thereof. The coated ultrahard abrasive particles are consolidated and sintered at a pressure and temperature at which they are crystallographically or thermodynamically stable.
Abstract:
Composites and methods relating to the use of inventive aluminophosphate compounds and films thereof with glass, ceramic and non-oxide ceramic substrates.
Abstract:
Methods of coating ceramic (e.g., barium titanate-based) particles, as well as articles and compositions formed from the coated particles are provided. The methods involve forming a mixture of barium titanate-based particles and at least two dopant metal solutions. According to some methods, a second solution (e.g., a base) is added to the mixture to cause the dopant metals to sequentially precipitate onto surfaces of the particles. The resulting particles are coated with respective layers having different dopant metal compositions. According to other methods, the mixture of barium titanate-based particles and at least two dopant metal solutions are added to a second solution (e.g., a base) to precipitate the dopant metal or metals to form a coating on surfaces of the barium titanate-based particles. The resulting particles are coated with a homogeneous coating. The coated barium titanate-based particles produced according to the methods of the invention may be further processed to form, for example, green layers and/or dielectric layers in electronic devices such as MLCCs. The methods provide a uniform distribution of the dopant metals throughout the barium titanate-based particulate composition and limit dopant segregation which can improve properties of the dielectric layers amongst other advantages.
Abstract:
A composite nanoparticle material comprising a plurality of cores and a plurality of shells. At least one of the cores is encapsulated by one the shells. An oxygen storage material comprising a plurality of oxygen storage catalyst cores. A plurality of oxygen transport shells. At least one of the oxygen storage catalyst cotres is encapsulated by one of the oxygen transport shells.