Papers by Author: Hui Wang

Abstract: Under the liquid-phase hot-pressing technique, the multi-scale titanium diboride matrix nanocomposite ceramic tool materials were fabricated by adding both micro-scale and nano-scale TiN particles into TiB2 with Ni and Mo as sintering aids. The effect of content of nano-scale TiN and sintering temperature on the microstructure and mechanical properties was studied. The result showed that flexural strength and fracture toughness of the composites increased first, and then decreased with an increase of the content of nano-scale TiN, while the Vickers hardness decreased with an increase of the content of nano-scale TiN. The optimal mechanical properties were flexural strength 742 MPa, fracture toughness 6.5 MPa•m1/2 and Vickers hardness 17GPa respectively. The intergranular and transgranular fracture mode were observed in the composites. The metal phase can cause ductility toughening and crack bridging, while crack deflection and transgranular fracture mode could be brought by micro-scale TiN and nano-scale TiN respectively.

Abstract: The suspension of multi-phase and multi-scale nanocomposite ceramic powders that showed long-term stability was obtained via a series of dispersing technologies including ultrasonic stirring, ball milling and adding dispersant etc. The effectiveness of preventing the suspension from agglomeration by adding the dispersant PMAA-NH4 is better than that of adjusting the pH value of the suspension with aqueous ammonia and hydrochloric acid or adjusting the pH value with aqueous ammonia and hydrochloric acid together with adding PMAA-NH4. A special microstructure was found through TEM that an α-Al2O3 particle is environed by TiN and Ti (C7N3) particles.