Ceramic Bonded

The grinding tools can be classified by their binder phase as resin bonded, ceramic bonded, or metal bonded (sintered or electrodeposited). 

Wear resistance of such tools strongly depends on the tool composition, the machined material, and the machining conditions, which makes this topic very complex [270-272], 

Mixtures of c-BN particles with other hard materials (e.g. Al203, SiC) can be bonded by vitreous material. The binder is sintered at 850-900 °C giving a crystalline phase which increases the mechanical strength and the hardness of the tools. A typical binder consists of Si02 10-20 wt%, ZnO 40-55 wt%, B203 15-30 wt%, Al203 2-10 wt%, MgO 2-10 wt%, alkali metal oxides 0.1-2 wt%, and Ti02 0.1-2 wt% [277, 278]. 

A c-BN - silicon nitride ceramic composite can be produced directly by sintering a mixture of c-BN powder and Si powder in N2 atmosphere. The composites have high resistance against heat, oxidation, and thermal shock [279]. 

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Curing. Some chemically bonded bricks requke some elevated heat treatment that is typically higher than the tempering process mentioned above, but less temperature than that requked to form ceramic bonds. One example is aluminosihcate brick bonded with phosphoric acid. A very strong... 

Special low fusing porcelain veneers are appHed to pure (unalloyed) titanium dental castings. It is important that firing be done either in a vacuum or inert atmosphere to protect the metal surface from excessive oxidation. The strength of the metal-ceramic bond is apparently adequate although the bonding is thought to involve primarily a mechanical rather than a chemical component. 

Ceramic bond formation and grain growth by diffusion are the two prominent reactions for bonding at the high temperature (1100 to 1370°C, or 2000 to 2500°F, for iron ore) employed. The minimum temperature required for sintering may be measured by modern dilatometry techniques, as well as by differential scanning calorimetry. See Compo et al. [Powder Tech., 51(1), 87 (1987) Paiticle Characterization, 1, 171 (1984)] for reviews. 

Barrett A. Johnson, Charles B. Rubenstein, Richard J. Martin and James O. Leckie Ceramic Bonding, Inc. 

Ceramic Bonding, Inc. (CBI) was founded in 1987 to develop technology for reliable, inexpensive, on-site conversion of heavy metal hazardous wastes to safe, useful materials, such as fine aggregate for construction applications. CBI s principal mission is to provide equipment that can be used by industry to eliminate the need for costly and environmentally unwise disposal of toxics at Class I dumpsites. 

Ceramic Bonding has embarked on a program to develop versatile equipment to aid metal fabricators in their efforts to eliminate hazardous waste generation. Because of the applicability of the CBI process to a variety of hazardous, heavy metal wastes, the CBI equipment is also a natural solution for site cleanup and municipal hazardous waste conversion. With this innovative technology, continued release of fugitive heavy metals into the environment can be halted. 

Barrett A. Johnson is president of Ceramic Bonding, Inc., Mountain View, California. 

J. 0. Leckie, Ph.D., is professor of environmental engineering, Stanford University, and technical advisor to Ceramic Bonding, Inc., Mountain View, California. 

Fig. 9.9. Relationship between values of elasticity and ceramic bonding material content from firing temperature. (After Moser, 1980)...

Bricks are fired or burned in kilns to develop a ceramic bond within the refractory and attain certain desired properties. This step does not apply to chemically or organically bonded products. Burned brick may be impregnated with tar or pitch to improve corrosion resistance. 

Ceramic bond formation and grain growth by diffusion are the two prominent reactions for bonding at the high temperatures [2000 to 2500°F (1093 to 1371°C)] employed. 

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