Papers by Author: Bo Quan Zhu

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Authors: Xiang Cheng Li, Bo Quan Zhu, Fei Zhao
Abstract: SiC whiskers are the common reinforced phases in alumina carbon refractories. In this paper, the effect of transition metal catalyst on the evolution of matrix phase and the formation of β-Si3Al3O3N5 whiskers were studied. It was found that the whiskers of both SiC and β-Si3Al3O3N5 in alumina carbon materials with the catalyst in reducing atmosphere were generated. The existence of catalyst can promote the nitriding process of Si metal and facilitate the formation of β-Si3Al3O3N5 whiskers. The growth mechanism of both SiC and β-Si3Al3O3N5 whiskers agrees with the vapor-liquid-solid model.
Authors: Bo Quan Zhu, Xue Dong Li, Hou Zhi Wang
Abstract: ZrO2-mullite compound powders were synthesized with zircon and aluminum sulfate in molten sodium sulfate. Na2ZrSiO5 was prepared as intermediate with zircon and sodium carbonate at 900°C for 3h. Then the mixture of resultant Na2ZrSiO5 and aluminum sulfate was heated at different temperatures in molten sodium sulfate salt. The ZrO2-Al2O3-SiO2 compound powders were obtained after washing away the solvable salts. The results showed that the compound powders synthesized at 800°C were tetragonal ZrO2, SiO2 and Al2O3; the powders synthesized at 1000°C were monoclinal ZrO2 and mullite. The mullite in compound powders became to decompose when the reaction temperature increased over 1100°C.
Authors: Bin Xiang Fang, Bo Quan Zhu, Wen Jie Zhang, Xue Dong Li, Zheng Yun Fan
Abstract: The Al/AlN bonded corundum based multiphase material was prepared by raw materials of fused alumina and metallic aluminum powder by in situ reaction at 1100°C for 3h in N2 . The XRD analysis showed that the mineral phases of prepared material are corundum, metallic aluminum and AlN respectively. The SEM investigation revealed that both tetragonal whiskers and hexagon powders of AlN were formed. The results of hydration tests indicated that the rate of weight gain and pulverization of the material were negligible and the ratio of residual crushing strength was kept at a high level. The XRD patterns of samples after hydration tests identified that the AlN phase still remained although a small amount of AlOOH and Al(OH)3 was formed due to the hydration of AlN. It is believed that the limited hydration of AlN should be contributed to the dissolution of O element to AlN. The hydration mechanism of AlN was discussed.
Authors: Bo Quan Zhu, Xue Dong Li, Rui Hao, Hou Zhi Wang
Abstract: Mullite powder was prepared through reaction of aluminum sulfate and silica in molten sodium sulfate media. The phase composition and microstructure of mullite powder were investigated. The results showed that high purity mullite is prepared by this method. The mullite powder exhibits needle-like whisker crystal with 50~100 nm in diameter and 3~8 #m in length. It is found that by this method mullite starts to form at 900oC, the quartz phase is disappeared about 1000oC, and mullite begin to decompose when the temperature is over 1100oC. Thus, the reasonable synthesizing temperature is about 1000oC. This synthetic method is characterized by process simplicity, the temperature of mullite formation is lower than 200-400oC compared with other conventional methods.
Authors: Bo Quan Zhu, Xiang Cheng Li, Cong Jin Jin, Zeya Li, Shou Xin Tian
Abstract: β-sialon bonded corundum-based sliding gate plate was developed from raw materials of Al, metallic silicon and alumina through nitriding-reaction process. It was found that the effects of β-sialon content on the physical properties are significant and the mechanical properties of developed sliding gate plate are strongly related to the Z-value. The materials with Z value of 2 and 20wt% β-sialon, exhibit the highest hot modulus of rupture and cold crushing strength. It was also found that sialon bonded corundum-based material has good oxidation resistance because a protective layer is formed during oxidation process.
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