Taoyong Liu

Effect of sintering temperature and time on preparation of ceramic tiles made from tungsten tailings

The present study aims to investigate the effect of sintering temperature and time on the sintering behaviour of ceramic tiles from 100% tungsten tailings. The relationship between phases, microstructure and physicomechanical strength was analysed. The results demonstrated that there are three phases, namely, quartz (SiO2), kyanite (Al2SiO5) and hematite (Fe2O3). The microstructures of pores varied from irregular ones with interconnected porosity to isolated and rounded ones in the ceramic tiles as the sintering temperature and time increase. In addition, high sintering temperature and long sintering time promise greater pores. The sample that was sintered at 1050°C for 1 h has a compact structure and superior physicomechanical strength of the ceramic tiles: low water absorption (0.2%), high bulk density (2.42 g cm− 3) and flexural strength (91 MPa). The results illustrated that utilisation of pure tungsten tailings in ceramic tile production constituted a feasibility of adding value.

Synthesis, Structure and Properties of MgO-Al2O3-SiO2-B2O3 Transparent Glass-Ceramics

MgO-Al2O3-SiO2-B2O3 system transparent glass-ceramics have been prepared by conventional melt-quenching method followed by controlled crystallization, and their properties were also studied. The crystalline phases, crystal morphology, physical and light transmittance properties of glass-ceramics were characterized by DSC, XRD, FTIR, FE-SEM, thermo-mechanical analyzer and UV spectrophotometer. The results indicated that the crystal phase μ-cordierite turned to α-cordierite with increase in heat treatment temperature, and cordierite nanocrystals with size less than 50 nm were precipitated from the matrix glass, which was confirmed by the X-ray and SEM results. It is observed that the main elements in the glass-ceramics are uniformly distributed from EDS element distribution maps. The light transmittance of glass-ceramics obviously decreases with rising of crystallization time. All things considered, when the parent glass was crystallized at 1045 °C for 1 h, the prepared glass-ceramics possesses good light transmittance (76 %), lower density (2.498 g/cm3), lower thermal expansion coefficient (2.469 × 10− 6/°C), higher bending strength (167 MPa), compressive strength (376 MPa) and higher Vickers hardness (7.8 GPa). The combination of excellent mechanical, thermal and optical properties makes this family of transparent glass-ceramics showing potential applications.

Sintering behaviour and characterisation of low-cost ceramic foams from coal gangue and waste quartz sand

New ceramic foams have been successfully synthesised with coal gangue and waste quartz sand, which supply a feasible way to recycle these hazardous solid wastes. An objective of this research was to investigate the sintering behaviour and effects of sintering conditions on the crystalline phase change, microstructure and main properties of final ceramic foams. Good correlations among porosity, thermal conductivity, water absorption, bulk density, mechanical properties were studied. Results indicated that increasing sintering temperature or time had similar effects on the physical–mechanical properties. Samples sintering at 1140°C for 1 hour exhibited the highest porosity (87.5%), lowest bulk density (0.39 × 10−3 kg m−3), lowest thermal conductivity (0.085 W·(m K)−1), moderate water absorption (9.38%) and adequate flexible strength (2.4 MPa). Combined with excellent properties and low-cost characteristics, the new development for ceramic foams preparation will be widely used in building insulation materials for no-load bearing walls.