Abstract
Slip casting is one of the techniques used to produce ceramics, silisides and carbides with a complex shape. In this investigation, the effects of Fe, which contaminates pulverized CrSi2, on the relationship between slip viscosity and pH, the density of green state and the thermoelectric property of the sintered CrSi2 have been examined. The following are the results obtained.
The Fe content in CrSi2 powder increased linearly with increasing time of ball-milling. After 8.85×105 s of milling, Fe of 2.3 mass% was introduced to the powder, an average particle size of which was 1.05 μm. The slip viscosity increased and the apparent density of the green sample decreased with the Fe content. However, since the Fe acted as a sintering accelerator, the density of sintered CrSi2 was increased. The thermoelectric power α, the electrical resistivity ρ and the power factor α2⁄ρ of the sintered CrSi2 were lower than those of high purity one at room temperature by about 21%, 30% and 11%, respectively. When the temperature difference was 800 K, however, the effective maximum power of the CrSi2 was only a few percent lower than that of the high purity one and was independent of the Fe content in the CrSi2 powder. Therefore, when the slip casting technique is applied to production of CrSi2 powder, it is not necessary to remove the contaminating Fe,and CrSi2 thermoelectric materials can thus be produced easily. As an application of the technique, sintered CrSi2 caps with straight and complex shapes have been manufactured by way of trial.
