Technology of Hot Pressing

The technology of concrete pressed at low w/c ratio has been developed simultaneously with the impregnation. The superplasticizers addition allows to produce the paste at w/c=0.20 [173]. Gypsum can be also replaced by 1 % calcium hgnosulpho-nate addition with 0.5 % KjCOj [174]. The porosity in this technology is minimized to 5 %, while in normal concretes it equals 25 to 30%. The hot pressing is also used and in this case porosity is below 2 % [175]. 

The objectives of this chapter are to determine the parameters of a new technology for high productivity, low cost of hot-pressed silicon nitride (HPSN) ceramic materials and to determine if an available grinding wheel system can be used for these applications. 

I 7 7 Non-Oxide Ceramics Structure, Technology, and Applications Table 11.8 Applications of hot-pressed sintered boron nitride. 

The forerunner of the rocket propellant containing perchlorates as oxidants was the American product, Galcit, developed in the Jet Propulsion Laboratory (JPL) of the Guggenheim Aeronautical Laboratory, at the California Institute of Technology. It consisted of asphalt as a fuel and potassium perchlorate as an oxidant, mixed hot. Originally the material was hot-pressed into rockets. However, at high pressures the flame penetrated between the charge and the walls... 

R. R. Wills, M. C. Brockway, and L. G. McCoy, "Hot Isostatic Pressing of Ceramic Materials," in R. F. Davis, H. Palmour III, and R. L. Porter, eds., Materials Science Research, Vol. 17 (Emeigent Process Methods for High-Technology Ceramics), Plenum Press, New York, 1984. 

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