Papers by Author: Jin Long Yang

Abstract: The attapulgite microspheres were produced by spray drying method and calcination process subsequently. The effects of calcination temperature on the microstructure and adsorption properties of methylene blue(MB) were investigated systematically. Results show that the median diameter of the microspheres increases after calcination. The adsorption capacity and removal efficiency of MB reaches the maximum values(96.62mg/g and 96.6%) after calcined at 600°C and decreases with the temperature increasing. The adsorption process can be described better by the pseudo-second-order kinetic model and fit the the Langmuir equation. The attapulgite microsphere shows good adsorption properties, which may be used as potential applications in various dyeing wastewater fields.

Abstract: Dense iron-containing hydroxyapatite (HA)/titanium composites were synthesized via pressureless sintering at a relatively low temperature using nanosized HA powders and Ti-Fe mixed powders. XRD analysis showed that desirable Ti phase still remained in the HA matrix. The addition of iron improved the densification by enhancing the sinterability of titanium, and reduced the decomposition rate of HA and the interaction between HA and titanium. The mechanical tests showed that both the flexural strength and fracture toughness of the composites were significantly improved. The Ti-Fe reinforcing particles exhibited plastic stretching and bridged an advancing crack, making a significant contribution to the improvement of mechanical properties of the composites.

Abstract: AlCl₃ was used as catalyst in the reaction. The reaction kinetics of aluminum and isopropanol was investigated in this paper. Metallograph showed that the surface of the aluminum bar had corrosive pitting. The reaction was zero order reaction when aluminum was overdosed. Reaction order was 0.75 when isopropanol was overdosed. Finally, catalytic mechanism of AlCl₃ was investigated and the reaction of corrosive pitting was the same as that in microbattery.

Abstract: The solid-reaction was applied to synthesize perovskite-phase Lanthanum Aluminate powders by using AlOOH and La2(C2O4)3 as raw materials, mineralizer AlCl3 and AlF3 as the additives, graund and mixed, then calcined at 800°C and 1200°C for 3 h. The XRD pattern shows that mono-phase LaAlO3 powders can be obtained at 1200°C, and the SEM analysis indicates that the AlCl3 and AlF3 can promote the grain growth and have a good control of morphology.

Abstract: Ceramic microbeads are increasingly being used for wear applications, especially for milling ultrafine powder. Research on friction and wear behavior of ceramics has become a more and more important subject in the area. In this paper, three kinds of ceramic microbeads ––mullite-zirconia, zirconium silicate and 95 alumina microbeads which were produced by Colloidal injection moulding technique were tested by SRV high temperature friction and wear test system, which the working condition of the ceramic microbeads as grinding media can be simulated to a certainty. The tests were done under dry friction and water lubrication respectively. Then their worn surfaces were observed using scanning electron microscopy. Through these experiments, the tribological properties and wear mechanisms of the self-wearing ceramic microbeads were investigated.

Abstract: The compressive strengths of three kinds of ceramic microbeads, ZrO2 toughened mullite, zirconium silicate and industrial zirconia, were studied in this paper. The densities of these ceramic microbeads were 2.9, 3.5 and 5.3g/cm3. The weighted average of compressive strength of these ceramic microbeads was 446.9, 500.8 and 917.3 N/mm2. It was concluded that the compressive strength of ceramic microbeads was proportional to the toughness and Young's modulus of the materials, and a larger diameter of the ceramic microbeads led to a higher compressive strength.

Abstract: The colloidal forming is an important process to prepare complex-shaped parts of ceramics, especially for industrialization of structure ceramics. It has been paid widely attention to by ceramic scientists, industries and governments in the past three decades. In 90’s, because the homogeneous green bodies were prepared using colloidal ways, many new colloidal forming processes were developed continuously such as gelcasting, DCC, TIF, colloidal vibration casting, colloidal injection moulding, HAS, and so on.. However, crackings of sintered bodies from colloidal ways have also often been occurred, especially for large size and solid parts of ceramics. In this paper, some important views about shrinkages from colloidal forming were discussed. The internal stresses in green bodies to prepare using colloidal forming resulted from the shrinkage of suspension during from liquid to solid. The shrinkage led to different cracks during sintering and/or debindering. Finally, it is put forward that the shrinkage from liquid to solid in colloidal froming have to be regarded in the future.

Abstract: The composite zirconium silicate microbeads with different pretreating process were developed in this paper. The wear loss of these microbeads was compared by testing of agitation mill. These microstructures with different micro-pores were compared by scanning electron microscopy. The pore size was found have obvious influences on the mechanism of the wear. Some solutions were proposed to overcome the micro-pores in the zirconium silicate composite microbeads.

Abstract: A heated sprue device for ceramic injection moulding was used to research the defects in injection-moulded technical ceramics. By use of the heated sprue device, the problem of sprue solidification was resolved and the density of the injection moulding specimens was increased while the defects eliminated. The influence of the processing parameters on the defects of the injection molding specimens was investigated in detail by X-ray radiography camera and photograph. It turns that the sprue solidification time has much influence on the defects in injection-moulded technical ceramics. Reasons causing the results above were also analyzed. Based on the research, bars of 20mm in diameter without macroscopic defects and turbine blade of fine property with Si3N4/SiC(w) materials were prepared by injection moulding.

Abstract: According to the heat transmission theory, in the aid of computer, the temperature distribution in the cylinder cavity was calculated. The temperature of the mould has much influence on the time for the injection material’s temperature of the cavity center to drop to the injection material softening temperature. The influence of the processing parameters on the density of the injection molding specimens was also investigated. It turns that the injection molding specimens’ density changes little with the increase of injection temperature and pressure, but changes a lot with the increase of holding pressure time.