Pyroceramics

Components, wt % Macor (Coming 9658) Dicor (Dentsply) Pyroceram (Corning) Code 9634 (Corning)... 

Some cuUet contaminants continue to be melting concerns. Pyrocerams, especially certain clear glass-like cookingware articles, are difficult to identify... 

The ramp of pressure to about 3 GPa observed in shock-loaded fused quartz has been used very effectively in acceleration-pulse loading studies of viscoelastic responses of polymers by Schuler and co-workers. The loading rates obtained at various thicknesses of fused quartz have been accurately characterized and data are summarized in Fig. 3.6. At higher peak pressures there are no precise standard materials to produce ramp loadings, but materials such as the ceramic pyroceram have been effectively employed. (See the description of the piezoelectric polymer in Chap. 5.)... 

To examine the response of PVDF to a higher pressure, ramp-type loading, an experimental arrangement with a ceramic Pyroceram similar to that of the fused quartz loading was employed. In this case, the loading wave transmitted through the Pyroceram is only approximately known and a simultaneous measurement must be carried out of the wave transmitted through the pyroceram and the response of the PVDF. 

D Pyroceram 9608 (Trade name of Corning Glass Works)... 

Key A Heatron T B Ncoceram-lS C Corning code 9650 D Pyroceram 9608 E Hercuvit... 

Pyrocerams, 21 381 Pyro-Chek 68PB, 11 470-174 Pyrochemical processes, in plutonium metal preparation, 19 676 Pyrochlore, 17 133-134, 140, 141 colorants for ceramics, 7 347t Pyroelectricity, 11 95, 100, 106, 107 Pyroelectric materials, smart, 22 708t, 709 Pyroform process, 25 171 Pyrogallol... 

Phase separation is not always a surface phenomenon. The glass that is eventually changed into a pyroceramic material has a nucleating agent mixed throughout... 

The phase separation producing opalescence and photosensitivity are production-created. That is, during the production of the glass, the phase separation occurs. The phase separation that occurs with pyroceramic material and Vycor requires baking the glass at high temperatures for an extended time. This elevated temperature provides the time for the molecules to align and/or separate themselves in a crystalline pattern. 

A third technique to produce tempered ware uses two glasses (or ceramics) formed together (laminated), each with different thermal coefficient of expansion. This is used to make Correll dishes by Coming. For this tableware, a pyrocer-amic material with one type of thermal coefficient of expansion is covered with another pyroceramic with a greater thermal coefficient of expansion and is then baked until the outer layer melts uniformly. Materials with greater thermal coefficients of expansion will expand more when heated and will contract more when cooled. The greater contraction (once cooled) of the outside material causes compression. 

A pyroceramic material is a special type of glass that has been devitrified by controlled nucleation of crystals. It has certain properties that are like glass and other properties that are like ceramics. Standard round tubing, not square, flat, or distorted walls. 

Hot Plates. These devices have a metal (cast aluminum, stainless steel, or some alloy), ceramic, or pyroceramic top. Underneath the top is an electric resistance heater. Hot plates are used for heating flat-bottom containers such as beakers and Erlenmeyer flasks. Because hot plate tops are non-porous, there are fewer concerns for spills affecting the heating elements as there are with heating mantles. Magnetic stirring devices are commonly included with hot plates. 

Pyroceramic and ceramic tops are impervious to most chemical spills. The exceptions are typically any of the chemicals that can attack glass, such as hydrofluoric acid, alkali solutions, and hot phosphoric acid. Metal-topped hot plates can take more physical abuse than ceramic or pyroceramic tops. In addition, with metal, there are no concerns about scratches or cracks that, on a pyroceramic top, could lead to further deterioration. Metal-topped hot plates are, however, subject to corrosion from chemical spills. 

Pyroceramic is a translucent material made by Coming that has both glass and ceramic properties. 

Fig. 3.12 Compressive strength versus strain rate for SiC fiber-reinforced pyroceram.39...

The low-expansion spodumene-eucryptite glass-ceramics are manufactured under the trade mark Pyroceram (with a numerical code), Cer-Vit, Hercuvit (USA), Sitall with a numerical code (USSR), Heatron, Neoceram, Miraclon (Japan), Jena 2000 Zerodur (FRG). 

The interfacial resistance between the coating and the lower thermocouple plate is different from the interfacial resistance between the substrate-measurement plate due to light oxidation of the steel substrate, which is not observed for the coating. We have observed that the interfacial resistance of ceramics depends primarily on the surface finish of the ceramic material, since ceramics are chemically stable. Therefore, we use an interfacial resistance that was previously measured between Pyroceram 9606, of the same surface finish as the FGM coating, and the upper thermocouple plate as our interfacial resistance function for the coating-measurement plate interface [6]. Thermal conductivity of the FGM coating can then be extracted from the total conductance data by using these interfacial resistances and the thermal conductivity data for 410 stainless steel. The estimated uncertainty of the measurement system is 5%. 

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