Theeformation of nonfired ceramic composites based on aluminophosphate cement is studied depending on treatment temperature and loading. It is established that the deformation of samples tested under heatingcooling cycles varies insignificantly (even under an external load of 0.3 MPa). The resistance of cement to deformation grows if it is subjected to heat treatment at higher temperatures or to repeated testing in heatingcooling conditions.The study of the deformation of nonfired ceramic composites under heating is a topical applied problem, since it makes it possible to develop new shrinkage-free materials, improve the technology of traditional materials, and estimate their stability in service under varying temperatures and mechanical loads. Various physicochemical processes occur in composites under heating and facilitate the formation of structures with different resistance to deformation. The technology of such products involves their pretreatment under normal conditions or in heating up to 800°C; however, their behavior under mechanical loads is not sufficiently investigated. The techniques for studying the deformation of products in such conditions have not been studied either. It is not clear which criteria should be used in developing instruments for measuring deformation in heating under a mechanic load and in choosing procedures for experiments and data processing, since available published data concern mainly fired refractories and ceramics. Therefore, the purpose of our study is to investigate the deformation of nonfired ceramic composites using the example of phosphate materials during their hardening, strengthening, and sintering depending on pretreatment temperatures. We have investigated the effect of mechanical loads in heating -cooling cycles.For our study we selected an aluminophosphate cement composite of the composition a-Al 2 O 3 -H 3 PO 4 (S : L = 2 : 1) commonly used for producing fire-resistant concrete and various special-purpose materials and products [1]. It was used to produce three groups of samples molded as cy-linders of height 76 ± 0.5 and diameter 36 ± 0.5 mm by semidry molding at 20 MPa and then exposed in air for 3 days at 20°C (the first group), preliminarily heat-treated at 300°C (the second group) or at 600°C (the third group). The deformation of samples was measured without loading or under an external mechanic load of 0.1, 0.2, and 0.In the beginning the deformation of the first group of samples was investigated. It was taken into account that cement curing occurs under heating to 300°C; moreover, its brittle failure is manifested within the temperature interval of 250 -300°C. The choice of treatment conditions for the samples of the second and third groups was made so that the curing and dehydration processes that have a significant influence on the structure and strength parameters of cement and, accordingly, on the deformation of samples would be totally completed during preheating. These processes are related to the formation of anhydrous aluminum phosphates (the tri...
Instrumentation and methodology for the experimental study of high-temperature strain and creep under load in phosphate-bonded nonfired refractories are described. Results for nonfired aluminosilicate, corundum, silicon nitride, and other refractory composites are reported.
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