Parameters of corundum spheres for packing high-temperature air heaters

Conclusions Parameters have been defined that need to be considered in choosing compositions and manufacturing techniques for spheres for packing high-temperature heaters. Tests have been made on the failure load, temperature for the start of deformation under load, creep strain under load, and strength reduction on thermal shock for these corundum spheres.The parameters have been determined for spheres with various compositions and made in various ways; they can be related to the porosity and crystal size.The creep varies from 0.6 to 5.2% at loads of 30 and 50 N in 10 h between 1300 and 1600°C. Shrinkage occurs on heating above the firing temperature, which attains 2.8% at 1950°C. The strength reduction after thermal shock is about 0.1%/°C.Defects also affect the deformability and strength.Translated from Ogneupory, No. 3, pp. 11–15, March, 1989.