Influence of Binder Content and Particle Size on Green Strength of WPP Parts

Abstract

Wet powder pouring (WPP) was developed as an alternative near net shape process to metal injection moulding (MIM). The amount of binder, which is necessary to obtain a sufficient green strength, is relatively low (2–5 vol.-%) compared to the amount used in the MIM process (about 30 vol.-%). This is advantageous with respect to short debinding times and low residual carbon and oxygen contaminations. A further reduction of the binder content or the application of the WPP process to new materials would be promoted by an understanding of the dependence of green strength on particle characteristics and binder content. In the present investigation the green strengths of stainless steel WPP parts were determined for different particle size distributions and different binder contents (2–8 vol.-%). The green strength was in the range 3 to 7 MN m⁻² and the fracture mode was always brittle. A simple fracture mechanical model was developed, which was able to explain the observed relations between binder content, particle size, and green strength. PM/0658