The development of a technique for extrusion and sintering of beryllia

Abstract The development of an extrusion and sintering technique for the production of fine grain-size BeO of at least 95 per cent theoretical density is discussed. In this process Brush UOX powder, mixed with 2 wt % gum tragacanth, 10 wt % glycerine, and 17 wt % water is extruded under a pressure of 7000 psi, dried at 80° C, baked at 800° C, and subsequently sintered in an atmosphere of dry nitrogen (less than 100 ppm water vapour). The effects of sintering time in the range 1300–1700° C on density, grain size, microstructure, preferred orientation, and room temperature bend strength are reported and discussed. An average bend strength of 34 000 psi was attained for material with a grain size of 5 microns after sintering for 5 hours at 1350° C to a density of 2.90 g/cm 3 . Variations in type and content of plasticiser, mixing procedure, die entrance angle, and in drying and firing cycles were incorporated into the process and their effects on the quality of the sintered material are reported. Process modifications are proposed which should yield improvements in the structural homogeneity and mechanical properties of the sintered product.