Goal: Synthesis of SiAlON by reaction coating method using aluminosilicate natural raw material geopolymer (kaolin), corundum and silicon carbide and on its basis obtaining a composite with high physical and technical...Goal: Synthesis of SiAlON by reaction coating method using aluminosilicate natural raw material geopolymer (kaolin), corundum and silicon carbide and on its basis obtaining a composite with high physical and technical properties by hot pressing for use in armor and rocket technology. For the intensification of SiAlON formation and sintering processes, the influence of various additives was studied, such as: aluminum powder, elemental silicon, yttrium and magnesium oxides. Method: A SiAlON-containing composite with an open porosity of 15% - 16% was obtained by the metallothermic process and the method of reactive annealing in nitrogen. The resulting material was milled to a dispersion of 1 - 3 μm and hot pressed at 1620°C to obtain a product with high density and performance properties. We studied the process of SiAlON formation and the microstructure of the composite by X-ray phase, optical and electronmicroscopy analysis methods. Result: In the selected composition the β-SiAlON was formed at 1400°C instead of 1800°C, which was due to the mutual influence of the initial raw materials: geopolymer kaolin, perlite, corundum, aluminum, silicon, SiC, the development of the process is facilitated by the vitreous dopant perlite (96 glass phase). The use of perlite, which is eutectic with geopolymer at low temperatures, creates a good prerequisite for intensive diffusion processes with other components. Conclusion: A SiAlON-containing composite with high physical and technical properties was obtained in the SiC-SiAlON-Al<sub>2</sub>O<sub>3</sub> system by the method of reactive sintering and hot pressing, with the following properties: the strength limit in compression is 1940 MPa, and in bending it is 490 MPa. The process of making SiAlON has been studied using X-ray phase and electron microscopy analysis methods. The physical and technical properties of the obtained composite are studied by modern research methods.展开更多
Goal: To obtain SIALON containing composites by reactive sintering method in SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system. Using this method of synthesis, it became possible to obtain composites with...Goal: To obtain SIALON containing composites by reactive sintering method in SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system. Using this method of synthesis, it became possible to obtain composites with different percentages of SIALON. Our task was also to study the phase composition in the SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system. Method: The obtained mass was grounded in an attritor and the consolidated composite was obtained by hot pressing at 1800°C, 40 minutes, delaying at final temperature for 8 min. under 30 MPa pressure. To study the phase composition of the composites, we conducted an X-ray structural analysis on the DRON-3 device, and to study the microstructure, we conducted research on an optical microscope and a raster electron microscope “Nanolab 7” of the company “OPTON”. The values of the electrical parameters of the study composites were calculated on the basis of the obtained “lgp-t” dependence. Result: In SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system we obtained composites with a matrix composed of: β-SIALON, silicon carbide, corundum and nanoparticles of boron nitride. Conclusion: The phase composition of the obtained composite provides high physical-technical and performance properties of these composites. Compression strength—2187 MPA, Bending strength—285 MPa, Thermal expansion coefficient a20-700</sub>-3.8 × 10-60</sup> C.展开更多
文摘Goal: Synthesis of SiAlON by reaction coating method using aluminosilicate natural raw material geopolymer (kaolin), corundum and silicon carbide and on its basis obtaining a composite with high physical and technical properties by hot pressing for use in armor and rocket technology. For the intensification of SiAlON formation and sintering processes, the influence of various additives was studied, such as: aluminum powder, elemental silicon, yttrium and magnesium oxides. Method: A SiAlON-containing composite with an open porosity of 15% - 16% was obtained by the metallothermic process and the method of reactive annealing in nitrogen. The resulting material was milled to a dispersion of 1 - 3 μm and hot pressed at 1620°C to obtain a product with high density and performance properties. We studied the process of SiAlON formation and the microstructure of the composite by X-ray phase, optical and electronmicroscopy analysis methods. Result: In the selected composition the β-SiAlON was formed at 1400°C instead of 1800°C, which was due to the mutual influence of the initial raw materials: geopolymer kaolin, perlite, corundum, aluminum, silicon, SiC, the development of the process is facilitated by the vitreous dopant perlite (96 glass phase). The use of perlite, which is eutectic with geopolymer at low temperatures, creates a good prerequisite for intensive diffusion processes with other components. Conclusion: A SiAlON-containing composite with high physical and technical properties was obtained in the SiC-SiAlON-Al<sub>2</sub>O<sub>3</sub> system by the method of reactive sintering and hot pressing, with the following properties: the strength limit in compression is 1940 MPa, and in bending it is 490 MPa. The process of making SiAlON has been studied using X-ray phase and electron microscopy analysis methods. The physical and technical properties of the obtained composite are studied by modern research methods.
文摘Goal: To obtain SIALON containing composites by reactive sintering method in SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system. Using this method of synthesis, it became possible to obtain composites with different percentages of SIALON. Our task was also to study the phase composition in the SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system. Method: The obtained mass was grounded in an attritor and the consolidated composite was obtained by hot pressing at 1800°C, 40 minutes, delaying at final temperature for 8 min. under 30 MPa pressure. To study the phase composition of the composites, we conducted an X-ray structural analysis on the DRON-3 device, and to study the microstructure, we conducted research on an optical microscope and a raster electron microscope “Nanolab 7” of the company “OPTON”. The values of the electrical parameters of the study composites were calculated on the basis of the obtained “lgp-t” dependence. Result: In SiC-B4</sub>C-Si-Al-Al2</sub>O3</sub> system we obtained composites with a matrix composed of: β-SIALON, silicon carbide, corundum and nanoparticles of boron nitride. Conclusion: The phase composition of the obtained composite provides high physical-technical and performance properties of these composites. Compression strength—2187 MPA, Bending strength—285 MPa, Thermal expansion coefficient a20-700</sub>-3.8 × 10-60</sup> C.
