Synthesis of Mg₄SiO₂ glass ceramics in thermal plasma medium

The results of studies of the synthesis of Mg₄SiO₂ glass ceramics in thermal plasma medium are presented. For synthesis, an electric arc plasma torch with power of 12 kW was used. A series of experiments showed that the time of intense heating of refractory mixture during the synthesis of glass-ceramic sample does not exceed 30 s, the parameters of the sample are: density 3.56 g/cm³ and microhardness 15 GPa. It has been established that the phase composition synthesized sample is represented by the crystalline phase of forsterite Mg₂SiO₄ with the presence of low-intensity phase of silicon dioxide SiO₂ of the cristobalite modification and the presence of a high-temperature modification of clinoenstatite MgSiO₃. The content of the amorphous phase in the synthesized sample does not exceed 14 wt.%. The surface morphology of the synthesized sample is represented by dense packing of rhombo-dodecahedral crystals of the Mg₂SiO₄ phase, and the inner frame of the matrix is dense structure with clear linear arrangement of spherical inclusions of the MgSiO₃ phase with a diameter of up to 5 µm, in the center of which is the SiO₂ phase with a cristobalite modification having the form of scar with a length of 0.5 to 3 µm and width of 0.3 to 1 µm.

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