The effect of various silver tin oxide materials on contact performance under motor load (a.c.)
The new contact material AgSnO/sub 2/ which is replacing AgCdO in many applications, requires the addition of additives to improve electrical contact performance. These additives such as copper oxide (Cu/sub 2/O) and bismuth oxide (Bi/sub 2/O/sub 3/), can significantly affect contact performance. An investigation was undertaken to compare the changes in contact performance between silver cadmium oxide (internally oxidized) and three silver tin oxide based materials containing (1) no additive, (2) copper additive and (3) bismuth plus copper additives. Performance changes and physical characteristics of each material such as formability (tensile properties), contact resistance and contact material erosion (arc erosion) were evaluated. The silver tin oxide based materials containing copper additive exhibited significantly higher resistance to arc erosion than silver cadmium oxide based material and other silver tin oxide materials evaluated. The resistance to welding and changes in electrical resistance were dependent on the chemistry of each material. The results suggested that the chemistry of the material was the chief reason silver tin oxide based material with copper additive performed better than silver cadmium oxide based material under identical motor load.
Interface-level thermodynamic stability diagram for in situ internal oxidation of Ag(SnO2)p composites
We present a combined experimental and theoretical study on interfacial structure and thermodynamics in internally oxidized Ag(SnO2)p composites. The orientation relation between in situ formed SnO2 particles and the silver matrix was characterized using high-resolution transmission electron microscopy techniques. First-principles energetic calculations were then performed to predict the equilibrium interface structures and corresponding adhesion properties as functions of temperature and oxygen partial pressure. All results were combined to construct the interface-level thermodynamic stability diagram, for guiding the optimal design of internal oxidation parameters.
The Game Planners: Transforming Canada's Sport System.
The Game Planners studies the policy-making process in six Canadian national sports organizations, each of which deals with a different high-profile Olympic event. The authors argue that the creation of a "high-performance" sport system in Canada is due to pressure from three areas: the Canadian government, the physical education profession, and the sports community.