Application of nanotechnology in a silver/graphite contact material and optimization of its physical and mechanical properties

By applying nanotechnology, a new type of silver/graphite (AgC) electricalcontact was fabricated and characterized. The AgC coating powders were obtained through high-energyball milling and reducer liquid spraying-coating method. The as-prepared powders were examined bytransmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray diffraction(XRD). The results show that the thickness of graphite flakes milled for 10 h is about 50-60 nm andthe AgC coating powders exhibit flocculent structure with quite fine and homogeneous internalmicropores. XRD implies that the average crystalline size of silver in coating powders is about 50nm. The mechanical and physical properties of this newly developed AgC contact made from theabove-mentioned nanocrystalline powders by traditional powder metallurgy technique were measured.Compared with its counterparts made from other techniques, the properties of this new AgC contacthave been optimized. High surface energy and high-energy interfaces of the nanocrystalline AgCcoating powders provide powerful driving force for sintering densification. Moreover, the flocculentstructure of the powders is also an important factor to acquire fine density ratio.

“异境”与“凡人”关于向京

2013年10月19日，第四届“艺术长沙”在长沙市博物馆举行，迎来四位中国顶尖当代艺术家——周春芽、郭伟、丁乙、向京的创新之作，展出作品涵盖了雕塑以及带有迷幻、抽象色彩的油画作品。展出作品总计九十余件。向京作为唯一的女性艺术家倍受注目。向京1968年出生于北京文艺世家，1995年毕业于中央美术学院雕塑系，同年举办首展。1999年至2007年任上海师范大学美术学院雕塑工作室教师，2007年与丈夫——艺术家瞿广慈一起成立×＋0雕塑工作室，现工作、生活于北京。