Abstract:
A novel powder processing technique has been developed by combining
conventional powder injection moulding with polymer co-injection
moulding, to permit the in-situ surface engineering of metal or ceramic
components as an integral step within the processing cycle.
The new technique has been used to produce surface engineered iron based
components with either corrosion resistant or wear resistant surfaces, and
to produce alumina based components with toughened surfaces.
The most critical factor for the feasibility of surface engineered
components is that the sintering profiles of the skin and core materials
must be well matched or differential shrinkage or delamination will result.
A particular requirement of surface engineering is the ability to control the
surface engineered skin profile. Polymer injection moulding modelling
software was applied to predict the surface engineered skin profiles of the
surface engineered metal/ceramic components.
Successful skin profile prediction is dependent on the characterisation of
the feedstock materials being injection moulded. Several feedstocks have
been characterised for their material properties and first pass models
developed to predict the feedstock material properties as a function of their
individual material properties and mass or volume ratios.
It has been demonstrated that the design of the feedstock composition and
injection moulding process conditions can be optimised by the use of
computer-based
injection moulding modelling software to achieve the
desired surface engineered skin profile.
A methodology has been developed that outlines all the stages necessary
for successful powder co-injection moulding.