Yue Yunlong

Effect of Sulfate Ions on YAG Powders Synthesized by Microwave Homogeneous Precipitation

Abstract Using A1(NO 3 ) 3 ·9H 2 O, NH 4 A1(SO 4 ) 2 ·12H 2 O, Y(NO 3 ) 3 as mother salts, and urea as precipitant, YAG nano-powders were synthesized by microwave homogeneous precipitation. The composition, morphology, and phase transformation of precursor were analyzed by IR, XRD and TEM. The size distribution of YAG powders was characterized using laser diffraction method. The results show that sulfate ions influence the dispersion, composition and morphology of the YAG precursors. The addition of moderate sulfate ions can produce YAG powders with nano size and excellent dispersion at 1100 °C.

Fabrication and mechanical properties of TiC/TiAl composites

TiC/TiAl composites with different TiC content were fabricated by rapid heating technique of spark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl matrix was investigated. The results indicate that grain sizes of TiAl matrix decrease and mechanical properties are improved because of the addition of TiC particles. The composites display a 26.8% increase in bending strength when 10wt% TiC is added and 43.8% improvement in fracture toughness when 5wt% TiC is added compared to values of TiC-free materials. Grain-refinement and dispersion-strengthening were the main strengthening mechanism. The improvement of fracture toughness was due to the deflexion of TiC particles to the crack.

Preparation of Graphite Gangue Wall Body Materials By Solidifying Technique

The feasibility of producing graphite gangue wall body materials was discussed by the experiments of four kinds of hardeners solidifying graphite gangue. The result demonstrates that the physical performances of graphite gangue solidified brick samples with 8% hardener D reach the senior grade or the special grade in JC422-91. The study of solidification mechanism indicates that the hardeners produced pastes while being hydrated. In addition, they can activate the mineral compositions in clay to joint in the reaction to produce pastes and intensive framework.