Effect of thermal cycling processes on the structure and properties of heat resistant ceramics

Abstract

This paper deals with a study of the thermal aging process of a low-porosity refractory material based on the aluminum-titanium silicate system that exhibits high levels of thermomechanical properties. Aluminum titanate, mullite, and rutile form the main crystalline phases of the material. The experimental specimens were subjected to moderate thermal cycling in an automatic fast-heating PAS furnace available at the Minsk Porcelain Factory (temperature 1360~ duration of a cycle 6 h) and to abrupt thermal shocks (heating up to 1300~ and water quenching). In order to study the structure and properties, specimens were drawn at intervals of I0 cycles. It was established that after the first 30 cycles during the course of moderate thermal cycling (after a 180-h operation), no deterioration of the properties of the specimens occurred (in fact, some improvement was observed). This owes to the continuation of the sintering processes that could not proceed to completion during the firing operation. During the process of additional crystallization of the material, the defects developed due to thermal cycling can be 'healed' Subsequent increase of the duration of thermal cycling leads to rapid occurrence of the process of preferential recrystallizatio