METHOD OF MANUFACTURING CERAMIC SPHEROIDS Russian patent published in 1997 - IPC

FIELD: ceramics. SUBSTANCE: ceramic spheroids with size 0.2-2.5 mm suitable to be used in power engineering, fire extinguishing, chemical and food industries are manufactured as follows. Ceramic slurry containing ceramic material powder and thermoplastic organic binder in forming liquid with vertical temperature gradient 0.16-0.44 C/mm is dispersed. Depending on slurry density determined by amount of binder and density of powder, forming liquid is a glycerol-based mixture containing (in wt %): either 1-50 water, or 1-50 ethyl alcohol, or 1- 50 polyvinyl alcohol, or 1-20 of low-molecular carbohydrates such as glucose or sucrose. Organic binder is removed from prepared grains by heating in air the mix containing up to 50% of grains and powder-like sorbent: first to 110 C with rate 40-50 C/h maintaining this temperature for further 2-3 h, then to 300 C with rate 18-25 C/h maintaining this temperature for 3-6 h, to 400 C with rate 40-50 C/h maintaining this temperature for 2-3 h, to 500 C with rate 45-52 C/h, and finally to maximum temperature 1000-1200 C with rate 180-200 C/h maintaining this temperature for 1.5-2 h. Then material is cooled with rate 95-110 C/h. Pore-free spheroids as well as those with open porosity 1-50% or spheroids with internal cavity communicating through channels with environment may be thus manufactured. EFFECT: widened choice of ceramic produce. 6 cl