Dynamic pressing as a way of intensification of structural-phase transformations during sintering of ceramic materials

Abstract

The article presents the studies results of magnetic-pulse pressing in relation to ceramic masses based on non-sintering loam with the addition of coal flotation waste and the possibility of its use as a method for intensifying structural and phase transformations during sintering of masses was shown. A comparative characteristic of the properties of ceramic materials obtained by the usual mode of heat treatment at a temperature of 950 °C by the method of magnetic-pulse pressing with different amplitude of impact force was presented. To determine the operating parameters influence of the magnetic-pulse press on the samples properties, their pressing was carried out with a controlled voltage at a constant capacitance of the capacitor. It was found that an increase in the amplitude of the impact force from 6 kN to 15 kN leads to a decrease in the water absorption of ceramic samples from 21.6 % to 12.1—15.0 %, open porosity from 34.6 % to 21.6—27.0 %, and a threefold increase in mechanical strength. In comparison with samples of static pressing, the cold crushing strength of dynamic pressing samples increases by 34 % (from 8.7 MPa to 13.1 MPa) even with the minimum amplitude of the impact force (6 kN). The macrostructure, phase composition and properties of dynamic pressing ceramic samples obtained at firing temperatures of 920 °C and 950 °C have been studied. It was found that the samples had practically the same level of technical characteristics (water absorption, density, and strength) and they were similar in structure and phase composition (quartz, microcline, ɑ-hematite, X-ray amorphous phase). The possibility of obtaining ceramic materials with a completed process of the structural-phase composition formation and properties at a lower firing temperature has been established.
 On the basis of carried out studies, the possibility of using dynamic pressing as a method for intensifying structural-phase transformations during sintering of ceramic materials has been shown, which can serve as a reserve for energy saving when obtaining ordinary structural building ceramics of increased grade.