Minge Yang

Preparation and characterization of AgSnO 2 /Cu contact material by supersonic plasma spraying

The nanostructured AgSnO2 coating applicable to electrical contact material was prepared in the present study. Ag powders were mixed with 12wt.% of SnO2 nanopowders by means of high-energy ball milling, and then were sprayed on a pure copper substrate by supersonic plasma spraying. The phase composition and microstructure of the coating were characterized and the microhardness, bonding strength and electrical property were also measured. Results show that the AgSnO2 coating presents typical splat-like morphology of thermally sprayed coatings and consists of two different areas: one area is the fine SnO2 particles homogeneously distributed within the Ag matrix where the SnO2 particles are near-spherical and less than 100 nm, the other area is the Ag phase. Data from this study have demonstrated the technical feasibility of supersonic plasma spraying for the preparation of AgSnO2/Cu as a source of this material for electrical contact materials.

Biomorphic SnO2/C Ceramics Derived from Bio-Templates

Biomorphic SnO2/C ceramic has been prepared by molding into a composite billet and carbothermal-reduction under vacuum from ramie fibers/Sn(OH)4 precursors. The phase composition and microstructure of the prepared samples were characterized. The effects of the carbonization temperature and the other factors on the crystal structure, morphology and ingredients of the prepared samples were discussed. The results showed that there is no peak corresponding to carbon. So, it is inferred that the carbon exists in amorphous form and the sintering temperature have significant effects on the microstructure of SnO2 in biomorphic SnO2/C ceramics. The prepared products at the sintering temperature between 480°C and 630°C are biomorphic SnO2/C ceramics.

The Fabrication of Al 2 O 3 /C morph-genetic ceramics by biotemplating from ramie fibers

Based on the purpose of functional modification of woodceramics, a new kind of Al2O3/C morph-genetic ceramic materials with the microstructure of ramie fibers was prepared by molding into a billet and carbothermal reduction under vacuum from ramie fibers/Al(OH)3 precursors, which were prepared by impregnating Al(OH)3 sol into the pores of ramie fibers biotemplates using ultrasonic vibration technology. The formation mechanisms, phase composition and microstructure of the materials were analyzed and characterized respectively by using thermogravimetric analysis (DSC-TG), scanning electron microscope (SEM), X-ray diffraction (XRD) and some other experimental technology. In addition, friction and wear properties of woodceramics and Al2O3/C morph-genetic ceramics were studied comparatively using self-made abrader. The results showed that Al2O3/C morph-genetic ceramic materials had the natural tracheid structure of ramie fibers. Due to the introduction of hard-phase Al2O3, the anti-wear properties of woodceramics were greatly enhanced. The process provided a new way of functional modification of woodceramics.