Key Engineering Materials Vols. 434-435

Abstract: There are seven ceramic companies listed in Shanghai and Shenzhen Stock Exchanges. Because they belong to traditional industry sector, the profitability of most companies is weak. Listed companies experienced equity reform from 2005. In the paper, we analyze the impact of the reform and the impact of global financial crisis on those companies.

Abstract: This article describes various kinds of environmental pollution of ceramic industry in China, such as dust pollution, smoke pollution, water pollution and waste pollution of ceramics factories. In addition, some effective methods to control the pollution in ceramic factories are also discussed.

Abstract: This study reported the synthesis of Ni -based catalysts on Al2O3 support carried out by two different methods including co-impregnation and sequential impregnation. Different nitrate solutions of nickel, lanthanum, and magnesium were used for support impregnation. The calination process was carried out at 650 °C and 850 °C for 2 h under air. The XRD patterns of the catalyst samples presented main phases of Al2O3 and other diffraction lines corresponding to metal and oxide promoters; Ni, MgO and/or NiO, (Ni,Mg)Al2O4, La2O3 and La(AlO3). Prepared catalysts appeared in irregular shaped agglomerates of small particles of less than 1 micron. Surface area of co-impregnated catalysts increased with increasing calcination temperature while ones from sequential impregnation decreased except for those last impregnated with nickel salts. The La2O3-MgO-Ni/Al2O3 sequential impregnated catalyst had the highest surface area of 8.0-8.5 m2/g.

Abstract: AlN powders by the chemical vapor synthesis (CVS) process in the AlCl3-NH3-N2-H2 system were successfully synthesized. Gasified AlCl3 as a starting material was generated by pre-heating system and transported to the tube furnace in NH3-N2-H2 atmosphere. High crystalline AlN was synthesized at over 900°C. The average particle size of spherical AlN powders decreased from 250 to 40nm with increasing the reaction temperature of the tube furnace. Porous nano-size particles synthesized at high reaction temperature have low oxygen contents.

Abstract: The synthesis of AlN via self-propagating high-temperature synthesis (SHS) was attempted, using various ratio of Al powder mixed with AlN powder as diluents. Al and AlN powder mixtures with various weight ratios were ignited a nitrogen atmosphere with various amounts of carbon as additives. High crystalline AlN by SHS were successfully synthesized. The microstructure development during the reaction and the influence of these additives were determined by SEM and XRD analysis. A mechanism for the formation of high purity AlN with a very low content of residual oxygen (<0.8wt %) was proposed.

Abstract: The mixture of amorphous silica extracted from coal fly ash and fused silica was used to prepare density silica ceramic through slip-casting method. The XRD results showed that a large amount of cristobalite was formed at 1300°C which can weaken mechanical properties. The SEM results showed that glassy phase present from fused silica promoted ceramic densification. According to the experiment results, it was found that the bending strength was highest when mixing 65wt% fused silica and sintering at 1200°C for 4 hours.

Abstract: The output for ZrO2 fiber ferrule can be improved by ceramic injection moulding technology efficiently. In order to increase the ratio of ceramic powder which can improve mechanics quality and dimensional precision of ZrO2 ferrule, the gating system for ferrule mould is redesigned in this paper. After analytic calculation and simulation analysis, U-shape is adopted as the optimal cross-section shape in the cold flow channel injection mould for higher efficiency and filling effects. Moreover, three common cooling systems for ceramic injection mould are analysed and the results show that the cooling system with the pipe layout of double ring can be considered to be optimal to improve cooling efficiency, uniform temperature and heat balance effect of fiber ferrule mould.

Abstract: ZnO mesoscale superstructures (ZMS) with the sizes of 2 to 6 µm were synthesized by a simple solution method without any additives. The novel ZMS were assembled by numerous nanoparticles with the diameter of less than 100 nm, and no pores were found. X-ray diffraction shows that the ZMS mainly evolved in solution. The formation process of the ZMS accords to the classical theory of nucleation and growth. Photoluminescence (PL) analysis shows a sharp UV emission peak at 392 nm and a weak broad green-yellow emission peak at about 600 nm.

Abstract: The Mg-doped TiO2 was prepared by Sol-gel method at low temperature. The crystallization of TiO2 was studied by DTA, it was shown that the phase transition temperature of the Mg (NO3)2-doped TiO2 from amorphous to anatase and then to rutile significantly reduce. The XRD results show that the Mg-doped TiO2 has anatase and rutile annealed at 600 °C. Studies of photo-catalytic degradation show that the photo-catalytic activity of Mg-doped TiO2 thin film is higher than that of non-doped TiO2.

Abstract: In present work, ceria microspheres were synthesized by template hydrothermal method. Crystalline form of the as-synthesized ceria microspheres was defined by X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Dispersibility of ceria microspheres was comprehensively characterized using scanning electron microscope (SEM) observation and laser particle size analyzer. Furthermore, the ultraviolet light absorption performances of ceria microspheres with several different sizes were compared by ultraviolet visible spectrophotometer. The results showed that ceria microspheres presented excellent UV absorbent property and the size influence was remarkable.