Melting ceramic

Cera.micA.bla.tors, Several types of subliming or melting ceramic ablators have been used or considered for use in dielectric appHcations particularly with quartz or boron nitride [10043-11 -5] fiber reinforcements to form a nonconductive char. Fused siHca is available in both nonporous (optically transparent) and porous (sHp cast) forms. Ford Aerospace manufactures a 3D siHca-fiber-reinforced composite densified with coUoidal siHca (37). The material, designated AS-3DX, demonstrates improved mechanical toughness compared to monolithic ceramics. Other dielectric ceramic composites have been used with performance improvements over monolithic ceramics (see COMPOSITE MATERIALS, CERAMIC MATRIX). 

The present embodiment of an automotive catalyst consist of a monolithic support made of a high-melting ceramic material, cordierite, typically having 64 square cells per square centimeter cross-sectional area, with the walls between the cells being 150 pm thick. The walls are coated with a high surface "washcoat" having a BET area of 80-100 m /g. Since the... 

To sum up this examination, it can been seen firom the foregoing that onfy first steps have been taken in the study of silicon and titanium nitrides in the nanocrystalline state. The almost similar situation is in the case of another high-melting ceramic conq)Ounds. Problems, such as the selection of optimal UFPs preparation and conso-Hdation methods in term of NM quality and cost effectiveness, the role of admixture, the origin of hardness and its relationsh with grain size, nanophase equilibria in the systems Ti-N2, Si-N2, etc., and many others, remain unreso ed and need further consideration and clarification. 

Li JS. Wetting of ceramic materials by liquid silicon, aluminum and metallic melts. Ceram InL... 

Non-polymer fibers can be produced by many different methods, depending on the type of materials used. For example, carbon fibers often are made by high temperature treatment of carbon precursors in an inert atmosphere. Glass fibers and some ceramic fibers can be directly spun from their melts. Ceramic fibers also can be obtained by the calcination of ceramic precursor fibers or by the chemical vapor deposition of precursor gas on a carbon fiber substrate. Chapter 11 focuses on the formation of carbon and glass fibers. 

It is used in gyroscopes, computer parts, and instruments where lightness, stiffness, and dimensional stability are required. The oxide has a very high melting point and is also used in nuclear work and ceramic applications. 

It also has potential use in ceramic and glass formulas, as the oxide has a high melting point and imparts shock resistance and low expansion characteristics to glass. 

Melt flow rate Melt-formed ceramics Melt fracture Melting temperature... 

Glass-ceramic articles can be fabricated by means of either bulk or powder processing methods. Both methods begin with melting a glass of the desired composition. 

Heat treatment of related glasses melted under reducing conditions can yield a unique microfoamed material, or "gas-ceramic" (29). These materials consist of a matrix of BPO glass-ceramic filled with uniformly dispersed 1—10 p.m hydrogen-filled bubbles. The hydrogen evolves on ceranarning, most likely due to a redox reaction involving phosphite and hydroxyl ions. These materials can have densities as low as 0.5 g/cm and dielectric constants as low as 2. 

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