Effect of a calcined alumina additive amount on the properties of zirconia ramming mix on а phosphate bond

An effect of alumina additive amount on the main properties of ramming mix samples based on zirconia stabilized with calcium oxide on a phosphate bond was studied, as well as the processes of phase formation in these samples. It was found that, the alumina additive introduction activates the ZrO2 cubic phase destabilization, but does not cause softening of the samples structure. This is due to the fact that, as a result of the interaction of alumina with CaO released from the solid solution with ZrO2, elongated prismatic crystals of calcium hexaaluminate are formed, which reinforce and strengthen the samples structure. It was shown that, the samples composition containing 10 % alumina additive is optimal in terms of porosity, strength, and thermal shock resistance: ZrO2 + НfO2 — 83.52 wt. %; CaO — 3.86 wt. %; open porosity-— 15.9 %, cold crushing strength —62 N/mm2, thermal shock resistance (1300 ºС — water) — 6 thermal cycles, change in linear dimensions — 1 %. The obtained scientific results were used in the technology development of a new type of product — a mixture of powders for zirconia-alumina ramming mix, the manufacture of which was mastered at JSC "URIR named after A. S. Berezhnoy". The developed ramming mix is recommended for use, in particular, for making lining at the border of combustion and mixing zones of carbon black production reactors.

REFINEMENT OF REPAIR PROCEDURES OF THERMAL GENERATING SET COFFERING

Different repair procedures for coffering of thermal generating set from fireclay refractory are viewed. To improve repair technologies the authors propose formulations of soluble-glass heat resistant plactic compositions with spread effect raised from metallic aluminum in the form of fine-dispersed particles. Coffering is treated by method of liquid phosphate bond deep impregnation to enhance thermal and chemical resistance of coffering repair surface. Phosphate bonds permit to enhance density and resistance of compositions based on any binding substance.