Papers by Author: Jing Long Bu

Abstract: Mullite-corundum multiphase ceramic materials were prepared at 1400°C for 2h with bauxite chamotte and clay clinker as raw material (size<74 μm), molded at pressure of 50 MPa. Effect of raw materials composition on sintering and themal shock resistance of composite were researched by measurements of apparent porosity, bending strength，thermal shock resistance and thermal expansion rates, and analysed by XRD and SEM. The results showed that the best weigh percentage of raw materials with better sintering and themal shock resistance are bauxite chamotte 50 wt%, clay clinker 50wt% for mullite-corundum multiphase ceramic materials. The test results for high temperature gas cleaning dust removal technology development and the application of the composite ceramic material has important application value.

Abstract: Zirconyl chloride was used as zirconium source and fused silica particles were used as main raw material. First of all, the composite powders were prepared by wet chemical synthesis using ammonia as the precipitator and polyethylene glycol as the dispersant. Then, fused silica nanozirconia composite ceramic containing nanometer particle zirconia with different contents (5%, 15%, 25% and 35%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The bulk density and bending strength were measured, microstructure was observed by SEM. The result indicated bulk density and bending strength of composite ceramic increase and microstructure becomes denser with content of zirconia increasing. Bulk density of composite ceramic increases and bending strength which reaches maximum at 1350°C firstly increases then decreases with the increase of sintering temperature. Both high sintering temperature and nanozirconia possessing high energy interface can improve the composite ceramic sintering.

Abstract: Fused quartz powder (d₅₀=19μm) was used as raw material, nano-Yb₂O₃, nano-Nd₂O₃ and nano-Dy₂O₃ were dividedly used as additive with dosages of 3% each. Fused quartz ceramic materials were sintered in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1h. The influence of rare earth nanooxides on sintering and crystallization of the fused quartz ceramic were researched by measurements of apparent porosity, bending strength and thermal expansion ratios, and analyses of XRD and SEM. The results showed that samples added nano-Yb₂O₃ and nano-Nd₂O₃ have lower apparent porosity, higher bending strength and lower thermal expansion rate. It can be deduced that additives nano-Yb₂O₃ and nano-Nd₂O₃ have obvious effect on facilitating sintering and inhibiting crystallization of fused quartz materials at experimental temperatures.

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron runner, and partial bauxites of size 8-5 mm, 5-3 mm, 3-1 mm and 2O₃-MgO-C materials from spent ladle bricks, respectively. Effects of particle size and content of the recycled materials on sintering performance of the castable were investigated. The sintering performance was analyzed by measuring apparent porosity, room temperature flexural strength, room temperature pressure strength and high temperature flexural strength. The results showed that the apparent porosity of the samples overall tended to increase with content of the recycling materials increasing, while room temperature flexural strength, room temperature pressure strength and high temperature flexural strength of the samples reduced gradually. 8-5mm and 5-3 mm particle of 5%-15% the recycling Al₂O₃-MgO-C materials was more suitable for the preservation of high temperature flexural strength and room temperature strength of the samples than 3-1 mm and < 0.074 mm particle.

Abstract: In this experiment, preparation of samples were based on original ratio of bauxite matrix Al₂O₃-SiC-C castable for iron tap channel, and partial bauxites of size 8-5 mm, 5-3 mm, 3-1 mm and 2O₃-MgO-C ladle bricks, respectively. Effects of recycling ladle lining materials on phase composition and microstructure of Al₂O₃-SiC-C castable for iron runner were investigated by XRD, SEM and EDS. The results showed that new phases SiO₂ and (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ were formed in the castable at 1450 oC in air atmosphere, and the spherical (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ was formed on external surface of recycling Al₂O₃-MgO-C particle. thereinto, SiC oxidation to formed SiO₂ with flow pattern character was key element of the phase (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ formation. The more fine and uniform of recycling Al₂O₃-MgO-C particles, the more spherical (Mg_0.804Ca_0.196)₃Al₂(SiO₄)₃ was formed in recycling Al₂O₃-SiC-C castable. Internal structure of theirs samples exhibited looser state with content increasing of recycling ladle lining materials.

Abstract: AlN-ZrO₂ system composites were prepared with Ca-stabilized zirconia (Ca-PSZ, particle size d₅₀=29.3 μm) and AlN power (d₅₀=0.5 μm) as raw material, MoSi₂ (d₅₀=2 μm) and Si₃N₄ (d₅₀=44 μm) as additives respectively, in N₂ atmosphere by pressureless sintering at 1600 °C. The phase compositions were investigated by XRD. The sintering performance of the composites was measured by the checking of the bending strength and the apparent porosity of samples. The anti-oxidation performance of the composites was analyzed by the checking of oxidation weight increased of samples. The results showed that phase compositions of the composites consisted of ZrO₂, ZrN, CaAl₁₂O₁₉ and CaA_l2Si₂O₈when the content of AlN was 8 wt %. The additives promoted the sintering of AlN-ZrO₂ system composites. As a result, introduction of the additives increased the oxidation of the composites due to oxidation expansion of phases ZrN.

Abstract: Fused quartz powder (d₅₀=19μm) was used as raw material, and nano-Nd₂O₃ was used as additive with dosages of 1% (in mass, similarly hereinafter), 2% and 3%. The effects of nano-Nd₂O₃ on crystallization and sintering behavior of the materials at various temperatures (1300 °C/1h, 1350 °C /1h and 1400°C /1h) were studied by measurements of apparent porosity, bending strength and thermal expansion ratios (RT~1200°C), and analyses of XRD and SEM. The results of XRD and thermal expansion ratios analysis showed that 3% nano-Nd₂O₃ additive had excellent effect on inhibiting crystallization of the samples sintered at 1350 °C and 1400°C. The results showed that the samples sintered at various temperatures with 3% nano-Nd2O3 had the lowest apparent porosity and more compact microstructure. This indicated that 3% nano-Nd₂O₃ had better effect on facilitating sintering of fused quartz materials.

Abstract: Silicon carbide with diffierent granularity and three grain composition was used as raw material. Silicon carbide refractory material was prepared in oxidizing atmosphere at 1400 °C, 1450 °C and 1500 °C for 3 h. Performence of samples were researched by measurements of apparent porosity, bulk density, bending strength at room temperature, thermal shock resistance and thermal expansion rate, and analyzed by SEM. The results showed that samples sintered at 1400 °C have low thermal expansion rate and apparent porosity, high bending strength and bulk density, good thermal shock resistance, compact texture as well. It can be deduced that (1.0-0.5mm) / (0.5-0.1mm) / (45μm) / (5μm) = 50 / 17/ 20/ 13 is the best grain composition to improve integrated performance of silicon carbide refractory material.

Abstract: Different dosages of BN-B₄C compound additive have been introduced for preparing specimen with fused quartz granule (d₅₀=10μm). Fused quartz ceramic materials were fabricated in reduction atmosphere at various temperatures for 1h. The characterizations were carried out by thermal expansion ratio, apparent porosity, cold modulus of rupture (CMOR) and SEM as well as by X-ray diffraction (XRD). The effect of BN-B₄C on the sintering, crystallization and properties of fused quartz was investigated. The result reveals that with increase of the temperature, the apparent porosity and CMOR of specimens decrease. The specimen C sintered at 1300°C possessed a maximum CMOR (22.31 MPa). The specimen C sintered at 1350°C has more compact microstructure. The lowest thermal expansion ratio of the specimens sintered at various temperatures was obtained when the dosages of compound additive is 3%. With increasing BN-B₄C content, the role on inhibiting crystallization was improved. The specimens containing 3 wt% BN-B₄C had obvious effect on inhibiting crystallization of the specimens sintered at various temperatures.

Abstract: Silicon carbide with diffierent granularity was used as raw material, quartz, silica fume, aluminum powder or alumina was used as additive with dosages of 1% (in mass, similarly hereinafter), 3% and 5%. Silicon carbide refractory material was prepared in oxidizing atmosphere at 1400 °C for 3 h. Performence of samples were researched by measurements of apparent porosity, bulk density, bending strength at room temperature, thermal shock resistance and thermal expansion rate, and analyzed by SEM. The results showed that samples added silica fume have low thermal expansion rate and apparent porosity, high bending strength and bulk density, good thermal shock resistance, compact texture as well. It can be deduced that 5% silica fume plays the excellent role to improve integrated performance of silicon carbide refractory material.