Jing Long Bu

A Potentiometric SO2 Gas Sensor with Solid Reference Electrode

A SO2 sensor based on Na-b-Al2O3 interfaced with an auxiliary electrode of Na2SO4 formed in situ and a solid mixture of Fe3O4, Fe2O3, 3Na2O.5Fe2O3 as the reference electrode was developed. The sensor displayed a Nernstian response to changes in the partial pressure of SO2.

Improvement in the Thermal Shock Resistance of Zirconia Ceramic by the Addition of Aluminium Titanate

ZrO2-Al2TiO5 composite materials with high bending strength and good thermal shock resistance expansion were prepared using partially stabilized zirconia (Y-PSZ) powders coated with Al2TiO5 by co-precipitation method. The effects of Al2TiO5 content on the sintering properties, phase composition, microstructure and thermal shock resistance of the zirconia ceramic were investigated．The results show that the apparent porosity of the samples decreased and their bending strength increased with the content of aluminum titanate increasing from 0 to 8 wt%. The samples with 5 and 8 wt% aluminum titanate addtion have excellent thermal shock resistance. The results showed that the addtion of aluminum titanate could enhance the mechanical strength and improve the thermal shock resistance of zirconia ceramic. The XRD and SEM analysis results indicated that the propriety improvement is relative with the change of the microstructure and the increase of tetragonal ZrO2 phase in the composites.

Study on Sintering Properties and Crystallization of Fused Quartz Ceramic Materials Containing BN-B4C

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.

Influence of Oxygen Donor Alcohols on Non-Hydrolytic Sol-Gel Synthesis of MgAl2O4 Spinel Nanoparticles

Magnesium aluminate (MgAl2O4) spinel nanoparticles were prepared by non-hydrolytic sol-gel method using anhydrous alcohols as oxygen donor. XRD and FTIR were used to characterise the effect of anhydrous alcohols on synthesis of MgAl2O4 spinel nanoparticles.The results showed that when the oxygen donor used in stoichiometric ratio for synthesizing MgAl2O4, anhydrous ethanol was the more effective oxygen donor than anhydrous isopropanol. But there was no remarkable effect on synthesis of MgAl2O4 spinel when the amount of anhydrous ethanol exceeded the stoichiometric ratio. The mean particle size MgAl2O4 spinel nanoparticles was in the range of 40 to 50 nm.

Effect of Rare Earth Nano-Oxides on Sintering and Crystallization of Fused Quartz Ceramic Materials

Fused quartz powder (size<0.04mm) was used as raw material, nano-Y2O3, nano-CeO2 and nano-La2O3 (size<0.08μm) were dividedly used as additives with dosage of 2% each. Fused quartz ceramic materials were sintered in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1h. The effect of rare earth nano-oxides on sintering and crystallization of the fused quartz ceramic were researched by measurements of apparent porosity, bending strength and thermal expansion rate, and analyses of XRD and SEM. The results showed that additives nano-Y2O3, nano-CeO2and nano-La2O3 had obvious effect of inhibiting crystallization of fused quartz, and the samples added nano-Y2O3 and nano-La2O3 were better. Sample added nano-Y2O3 had least thermal expansion rate. Sample added nano-La2O3 had higher bending strength, and it showed that nano-La2O3 had better effect on sintering of fused quartz ceramic. It can be deduced that nano-La2O3 plays the excellent role as the crystallization inhibitor of fused quartz materials.

Sintering Properties of Fused Silica/Nano-Zirconia Composite Ceramic

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.

Phase Composition Analysis of Recycled MgO-C Ladle Lining Materials

With the iron and steel metallurgy, cement, ceramic and other industries making a rapid development, the refractory consumption in our country is quite large. So how to recycle the used refractory materials effectively is more and more important. In this experiment, the phase composition of ladle lining bricks at slag line, rampart and bottom were researched systematically, to determine the phase composition change between the unused and recycled materials. It turned out that the low melting point minerals CaMgSiO4 and Ca3Mg (SiO4)2 formed due to the reaction between MgO and the impurity compositions like SiO2 and CaO from the melted slag and liquid steel. On the one hand, the formation of these low melting point minerals was one of the main reason for the damage of the recycled MgO-C ladle lining bricks. On the other hand, the alkaline magnesium carbon bricks had purification effect for the liquid steel as a result of the content reduction of SiO2 and CaO.

Improvement of Thermal Shock Resistance Performance of High Alumina Ceramic Filter Support

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.

Research on Mullite-Corundum-Aluminium Titanate Composite

Mullite-aluminium titanate-corundum composite was prepared at 1300°C with refractory clay, aluminium titanate and high alumina grog as raw material, molded at pressure of 50MPa. Effect of raw material ratio on sintering and themal shock resistance of the mullite-aluminium titanate-corundum composite was researched by measurements of apparent porosity, bending strength and residual strength after water-cool, and analyses of XRD and SEM. The results showed that as refractory clay content, apparent porosity of samples decrease, bulk density and bending strength increase. When the weight ratio of refractory clay, aluminium titanate and high alumina grog is 60/10/30, themal shock resistance of sample is excellent, The XRD and SEM analysis results indicated that the mechanical and thermal proprieties are relative to the microstructure and crystal phases of the composite materials.

Effects of Recycling Ladle Lining Materials on Phase Composition and Microstructure of Al2O3-SiC-C Castable for Iron Runner

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 (Mg0.804Ca0.196)3Al2(SiO4)3 were formed in the castable at 1450 oC in air atmosphere, and the spherical (Mg0.804Ca0.196)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 (Mg0.804Ca0.196)3Al2(SiO4)3 formation. The more fine and uniform of recycling Al2O3-MgO-C particles, the more spherical (Mg0.804Ca0.196)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.