The influence of the PMMA content in a composite binder comprising PMMA and
PEG on the moulding, debinding and sintering behaviour of injection moulde
d samples of 316L stainless steel powder has been investigated. The PEGs co
mponent of the binder is readily soluble in water, so that, after leaching,
a network of open pores is provided to facilitate the extraction of the PM
MA by pyrolysis. This has been shown to lead to a reduction in overall debi
nding time. It is shown in the present study that reduction in the PMMA con
tent allows injection moulding to be carried out at a lower temperature, wh
ile having the unfavourable consequences of reducing the stiffness and the
green and brown strengths of the mouldings. It was also found that the moul
dings had to be left in the die for a longer period before ejection because
the temperature at which the binder stiffens was significantly reduced. It
was shown that reducing the PMMA content of the binder enhanced the rate o
f removal of the PEGs during the leaching. The sintered densities of the mo
uldings were found to increase as the PMMA content increased as, consequent
ly, did the hardness. (C) 2001 Elsevier Science B.V. All rights reserved.