Effect of process conditions on the thermoelectric properties of CoSi

A CoSi n-type thermoelectric material is prepared using a powder metallurgy technique with two different starting materials. Measurements of thermoelectric power, α, electrical conductivity, σ, and thermal conductivity, κ, are carried out in a temperature range from room temperature to 973 K under 10−1 torr vacuum. Thermoelectric power and electrical conductivity are found to decrease with increase in temperature in all cases. Thermal conductivity of CoSi fabricated from pulverized powders of cast materials is found to be lower than that from powders of reactive sintered materials, which result should come from the difference in porosity in specimens. It is shown that the thermoelectric figure of merit, Z, of the present CoSi currently fabricated by powder metallurgy is higher than that prepared by conventional ingot metallurgy methods.