Semi-Continuous Pressure Sintering.
Final rept. 15 Jul 68-8 Oct 69,
BOEING AEROSPACE CO SEATTLE WA
Pagination or Media Count:
A unique device was designed and constructed for the purpose of densifying ceramic powders by hot rolling. MgO 2 wo LiF has been fabricated into thin translucent plates up to 7 inches long and 1.2 inches wide. The powder was tamped into metal tubes, vacuum out-gassed, and hot rolled at temperatures and pressures up to 1025C and 8350 psi, respectively. The rolling speed was varied between 4 inmin and 0.5 inmin and the roll diameter was 11 inches. A few rollings were also made with Al2O3, BaTiO3 and ZnS. Problems of the dense ceramic sticking to the tube were overcome by using graphite cloth inerts which behaved as a deformable barrier layer. Besides requiring a deformable barrier layer to prevent sticking, adsorbed gases must be allowed to escape and lateral constraint must be provided. Modulus of rupture values up to 59,000 psi were observed for hot rolled MgO 2 wo LiF. Several rollings were performed using a channel rather than a tube enclosure with encouraging results. Loading the powder and removing the dense ceramic were simpler and out-gassing prior to rolling was not necessary as it was when a tube was employed. Equally high densities and strengths were observed. Author
- Ceramics, Refractories and Glass