The paper presents the results of the analysis of the state diagram of compounds in the system А12O3-SiO2. It has been found that the presence and the concentration of oxygen have a very important effect on formation of compounds with a crystalline structure in different syngony based on SIALON. Oxygen contributes to transition of the metastable AlXSi3-XN4compound into stable one. The parameter of structural “friability” of compounds has been used in the analysis of thethermodynamic stability of compounds in the Al-Si-N-O system. It has been foundthat the SiAl4O2N4 compound with the 12H-SIALON structure (Pearson symbol hP32) has the greatest thermodynamic stability among the compounds under study in this system.
Heat-resistant materials are commonly used in industry where technological processes require high temperatures. The research represents possibility to obtain Al2O3–SiO2–ZrO2 based composition from local raw like zirconium silicate of Tugansk deposit of Tomsk region and white clay of Kailinsk deposit of Kemerovo region in Russia. There is possible application in gunning-mass form for restoration industrial thermal units. X-ray Diffraction Analysis demonstrates that mullite and zirconium compounds are formed in samples content after firing. The infra-red spectrums of heat-resistant gunning masses samples have been described by Fourier Transform Infrared Spectroscopy method. The thermal analysis has been performed using Differential Scanning Calorimetry and Derivative Thermogravimetry.
The paper presents research results of the β-SiAlON production from aluminum, silicon and urea nitrides using high-enthalpy thermal plasma flow. Physicochemical properties of β-SiAlON are studied by using the X-ray phase analysis, scanning electron microscopy, and differential thermal analysis. It is shown that at the spicified plasma jet parameters, a thermochemical reaction occurs with the formation of β-Si5AlON7. Three zones of the structure formation caused by the temperature gradient in the bulk material as a result of the plasma exposure, are identified and studied. The first zone is directly irradiated by the plasma. The second is the transition zone, which locates between the first and third zones. The third is the thermal heating zone provided by the heat transfer from the irradiated zone.
This article presents the results of studies of the effect of low-temperature plasma on a sample prepared from powders Si 3 N, AlN, urea solution and liquid glass. X-ray phase analysis established, that the use of plasma chemical synthesis produced the phase β-SiAlON compositions Si 5 AlON 7 with hexagonal system (Pearson symbol hP14, space group P6 3 /m. The diffractograms also show an X-ray amorphous phase and traces of initial compounds. A diagram showing the physical and chemical processes occurring during the interaction of the plasma flux with components in plasma chemical synthesis is presented.
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