Improvement of sinterability and mechanical properties of magnesia-silicate ceramics with enstatite phase from mixtures of serpentinite with silica additives

Abstract

The processes of obtaining a new type of ceramic proppants with high physical and mechanical properties based on serpentinite rocks, which were not previously used for this purpose are investigated. To increase the strength of ceramic materials, methods of improving the sintering of magnesia-silicate ceramics with a forsterite crystalline phase are considered. It was found that the activation of the sintering process is provided by the transformation of hard-to-sinter forsterite into enstatite. This is possible by adding of siliceous raw materials with different reactivity (quartz sand, marshalite, gaize and diatomite) to the pre-calcined serpentinite. The use of diatomite and gaize additives in an amount of 20–30% instead of quartz sand allows to reduce the firing temperature by 50–70 °C (from 1300–1350 °C to 1280 °C–1250 °C) and ensure the mechanical strength of pressed specimens up to 440 MPa. This made it possible to develop compositions and technological parameters for obtaining magnesia-silicate proppants with a bulk density of 1.58–1.62 g/cm3 at a firing temperature of 1250–1300 °C, capable of withstanding breaking pressure up to 52 MPa.