Papers by Keyword: Al₄SiC₄

Abstract: High temperature solution growth of Al₄SiC₄ single crystals was carried out from the melt of silicon and aluminium pieces in a graphite crucible used as carbon source (typically 1800°C under 1 bar of argon). The obtained crystals, in the mm scale, were then characterized by a variety of techniques including: Raman spectroscopy, transmission electron microscopy techniques, X-ray diffraction and UV-Vis-NIR spectroscopy. A good structural quality was revealed by TEM, ensuring a well resolved Raman spectrum. The UV-Vis transmission spectrum shows an optical gap located around 2-2.5 eV.

Abstract: The effect of phase composition and microstructure of Al₄SiC₄-Al₄O₄C composite refractories after sintered and immersion in the slag on its slag resistance was preliminary investigated. The penetration layer in refractories synthesized at 1700 °C resulted from loose microstructure led to worse slag resistance. While the refractories synthesized at 1800 °C presented better slag resistance because the dense microstructure and higher Al₄SiC₄ content inhibited the slag penetration and corrosion.

Abstract: Aluminum-containing ternary carbide, Al4SiC4-Al4Si2C5 composites, were synthesized using a mixture of bauxite, kaolin and carbon black as starting materials. The effects of raw materials ratio on the phase transformation and micromorphology of ternary carbide were investigated. The results indicated that the optimum condition for synthesizing Al4SiC4-Al4Si2C5 composites was 2 h sintering at 1900 °C in flowing argon atmosphere. Al4Si2C5, Al, Si and SiC formed when carbon black content was lower than stoichiometric amount. With increasing of carbon black content, the Al and Si content decreased and Al4Si2C5 content increased in the products. Al4SiC4 appeared when stoichiometric amount of carbon black was used, and about 20 mol% excess of carbon black promoted the formation of Al4SiC4.

Abstract: In Al-Si-C system, there are many compounds, of which Al₄SiC₄ is useful as high-temperature structure material and the antioxidant in carbon-containing refractory. In this paper, Al₄SiC₄ powders were synthesized by using kaolin grog, aluminum and activated carbon as raw materials. The phase changes of the synthesized samples were examined by X-ray diffraction (XRD), and the microstructure was observed by scanning electron microscope (SEM). The effects of synthesis temperature and the proportion of aluminum on phase compositions of Al-Si-C system were investigated. The results show plate-like Al₄SiC₄ powders can be prepared with optimal ratio of starting materials and synthesis temperature.

Abstract: Tabular structure of Al₄SiC₄-Al₈SiC₇ composites was successfully synthesized using a mixture of calcined bauxite, SiC and carbon black by a carbothermal reduction process. The effects of the amount of SiC addition and the heating temperature on synthesis of Al₄SiC₄-Al₈SiC₇ composites by carbothermic reduction were investigated. The results show that SiC amount played an important role in the content of the final products. With the increasing of heating temperature, the Al₄SiC₄ content increased and Al₈SiC₇ content decreased in the products, which indicated the formation and growth of Al₄SiC₄ were promoted.

Abstract: In this paper, A1₄SiC₄ was synthesized by using flint, aluminum and carbon black as raw materials，and they mass ratio was 28:50:22. The samples were fired at 1500°C、1600°C and 1700°C in an argon atmosphere. The phase compositions were determined by X-ray diffraction (XRD), the microstructures were examined by scanning electron microscope (SEM) and the elemental and quantitative compositions were determined by the energy dispersive X-ray spectroscopy (EDX). The results showed that the flint reacted with the carbon black, and produced Al₂O₃ and SiC firstly; meanwhile Al₄C₃ as intermediate product formed by the reaction between Al and C. Then a certain Al4C3 reacted with SiC, and produced A1₄SiC₄; most Al₄C₃ reacted with the Al₂O₃, and produced Al₄O₄C at higher temperature. Subsequently, the Al₄O₄C and the SiC reacted with carbon black, and produced A1₄SiC₄. The formed quantity of A1₄SiC₄ increased as the heating temperature was raised, and crystal structure was the flake structure of 1-2μm thickness and about 10μm length. The formation mechanism of A1₄SiC₄ was also discussed.

Abstract: Oxidation of carbon is the main problem in magnesia-carbon refractory bricks. Al₄SiC₄ powder is an excellent antioxidant which has obvious practical significance. It was prepared by vacuum sintering at 1700°C in vacuum sintering furnace. The effect of Al₄SiC₄ on the oxidation resistance of magnesia-carbon bricks were investigated at 1500°C. The thickness of decarburized layer of bricks was measured and the oxidized situation of the bricks was examined by XRD, SEM and EDAS. The decarburization layer became thin with adding Al₄SiC₄ powder. Magnesium alumina spinel (MgAl₂O₄) was determined to be present by characterization studies on Al₄SiC₄ added specimens and phase evolution of MgAl₂O4 spinel formation were investigated by XRD. The optical microscope and EDAS indicated that the spinel diminished the open pores owing to its volume expansion and formed a protective layer on the surface. The results suggested that the spinel had an excellent effect on the oxidation resistance of bricks. In addition, compared with adding other aluminum-containing antioxidants, the specimens added Al₄SiC₄ had better stability from high temperature to room temperature.

Abstract: Al4SiC4 is probably used as non-oxide raw material for high-temperature ceramics. Al4SiC4 was synthesized by using starting materials of metal-carbon, metal-oxide- carbon or carbides. In this paper, Al4SiC4 has been synthesized by using oxides (Al2O3 and SiO2) and carbon as starting materials through carbothermal reduction process. The oxidation properties in air and O2 atmosphere by TG method and the stability of the synthesized Al4SiC4 heated in moisture were investigated. Pure Al4SiC4 phase was synthesized when heating the mixture powder of Al2O3, SiO2 and C (C : Al2O3 : SiO2 = 8 : 2 : 0.8, in molar ratio) at 1700°C for 8h in flowing Ar atmosphere. The synthesized Al4SiC4 powder consists of platelet shape grains with size of 68μm length, 35μm width and 1μm thickness. Al4SiC4 obviously oxidized from 800°C when heated in flowing air or O2 atmosphere. When keeping Al4SiC4 powder in moisture, it was not observed to be reacted with water by XRD and SEM analysis.

Abstract: Single-phase and hexagonal plate-like Al4SiC4 powder was successfully synthesized using a mixture of Al(OH)3, SiO2 and carbon via a carbothermal reduction process. Two-step reaction was compartmentally observed during the calcination; the carbothermal reduction of SiO2 between 1300 and 1600oC and that of Al2O3 above 1500oC. The mechanisms which were responsible for the synthesis of the ternary carbide (Al4SiC4) powder were discussed.