Jin Long Yang

Controllable Forming Technology in Gelcasting

Controllable forming technology is one of the key problems for the industrial application of gelcasting. In order to solve this problem, various kinds of influence factors in gelcasting were investigated. Trace ions, ionic strength, pH, dispersant agent, premix, amount of initiator and catalyst, temperature, pressure, materials of container and inhibitor all have influence on solidification process of ceramic slurry. The forming process of gelcasting can be controlled effectively by adjusting these factors.

Hydroxyapatite/N-doped carbon dots/Ag3PO4 composite for improved visible-light photocatalytic performance

In this study, a new hydroxyapatite/N-doped carbon dots/Ag3PO4 (HA/N-CDs/Ag3PO4) composite was prepared by a facile hydrothermal approach and in situ ion-exchange reaction method. The photocatalytic performance of the as-prepared samples was investigated by the degradation of methylene blue (MB) under visible light irradiation. It was found that the HA/N-CDs/Ag3PO4 composite exhibited much higher photocatalytic activity and stability compared with HA/N-CDs and HA/Ag3PO4. In addition, the effect of the amount of silver loading on the photocatalytic activity of the composite was evaluated. The experimental results showed that a higher silver loading amount led to a decrease of both the UV-Vis absorption and photocatalytic performance. A suitable content of silver loading produced the highest photocatalytic activity. The substantial improvement in the photocatalytic performance of the composite can be attributed to the synergetic effects of HA support, CDs and the formed Ag3PO4, which led to an increase of active sites, suppression of the electron–hole recombination, and the stability improvement of Ag3PO4. The HA/N-CDs/Ag3PO4 photocatalyst synthesized via a cost-effective route is a promising candidate in organics removal.

Study on Preparation of Spherical Zirconia Powder in Microemulsion System and its Surface Characteristics

In this paper, a W/O microemulsion system composed of cyclohexane / water / TritonX-100 / hexyl alcohol is adopted to prepare ultrafine spherical zirconia powder via the reaction between the precipitant and zirconium salt solved in the nano reactors. Furthermore, the powder’s surface characteristics and aqueous dispersibility that strongly depends on the post-treatment process are investigated thoroughly.

Technology and Equipment on Collide Injection Moulding of Ceramics

Colloidal injection moulding of ceramics (CIMC) is a new ceramic forming technique that combines the advantages of gelcasting and injection moulding. It can inject nonplastic slurry into the mould and solidification course of ceramics slurry can be controlled by both temperature and pressure. Quick mixing technique ensures that ceramic slurry will not be solidified before casting. The equipment of CIMC was designed and developed. High performance ceramic components with complex shape have been manufactured by this equipment.

The Compressive Strength of Ceramic Microbeads

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 Youngs modulus of the materials, and a larger diameter of the ceramic microbeads led to a higher compressive strength.

Wear Mechanism of Ceramic Microbeads as Grinding Media

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.

Storage Stability of Ceramic Slurries for Gelcasting

In the industrialization of gelcasting, storage of ceramic slurry has been one of the key problems that must be solved. Except for sedimentation of ceramics particle, solidification properties of slurries were also affected after long-term storage. In this article, some factors in the process of slurry were discussed, and corresponding solution methods were put forward.

Effects of Calcination Temperature on the Microstructure and Adsorption Properties of Attapulgite Microspheres

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.

Effect of Micro-Pores after Sintering on Wear Behavior of Zirconium Silicate Composite Microbeads

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.

Shrinkages during from Liquid to Solid in Colloidal Forming

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.