THE USE OF OVERPRESSURE IN THERMOLYTIC DEBINDING OF MOLDED CERAMIC BODIES

A furnace within a pressure vessel capable of withstanding 0-1 MPa and temperatures up to 600 degrees C is described The furnace allows the pyrolysis of injection moulded ceramics to take place at higher heatin g rates than is possible at atmospheric pressure without defects cause d by bloating or cracking. The effectiveness of the method is describe d for a commercial injection-moulding composition pyrolysed in nitroge n. The various effects of gas pressure on the process are listed and t he main beneficial effect is considered to be the increase in boiling point of the polymer-degradation product solution which forms the cont inuous phase. In the early stages of heat treatment, this allows more rapid mass transport both by diffusion and fluid flow.