Sintering viscosity and sintering stress of nanostructured WC–Co parts prepared by powder injection moulding

Abstract

The uniaxial viscosity and sintering stress of WC–10Co–0·9VC (wt-%) were obtained by a loading dilatometer as functions of fractional density (0·64<ρ<0·93) and temperature (1084<T<1297°C) according to a Newtonian constitutive law commonly used to simulate sintering. The viscosity is suggested to follow In η = a+Q/RT+bρ with the values of a = 52·3±4·5 and b = 16·8±0·2. Q reflects the temperature dependence of η and estimated to be 502±52 kJ mol⁻¹. The sintering stress exhibited almost a constant value in the range of 0·05–0·4 MPa. It is shown that Rahaman's model best fits the experimental results. This paper describes experiments performed on nanostructured WC–Co feedstock to provide information on the characteristics of powder injection moulding green parts that are needed for sintering simulation. The validity of the calculation is addressed on the base of microstructural changes upon sintering.

Keywords:

• Sintering
• Cemented carbide
• Powder injection moulding
• Viscosity
• Constitutive equations