Thixoforming : Semi-solid Metal Processing

Figure 8.40 SEM image depicting a typical microstructure of gas
pressure sintered silicon nitride (GPSN) consisting of elongated
b-Si3N4 grains in a matrix of fine, equiaxed a-Si3N4, grains,
surrounded by a glassy grain boundary phase containing large
amounts of sintering additives Al 2O 3 and Y 2O 3.
samples were subjected to thermal shock similar to the conditions present during
application.
Likewise, the behaviour of potential die materials in contact with solid and semisolid
steel was investigated using a tailor-made contact corrosion test (Figure 8.41).
The test setup permits the investigation of chemical interaction between diffusion
couples under static load in different atmospheres. For steel contact corrosion tests,
the standard test temperature was 1300 C, in air or under flowing argon. Selecting a
test temperature below or within the melt interval of the respective alloy additionally
permits evaluation of corrosion effects in contact with metals in the solid or semisolid
state.
Figure 8.41 Schematic diagram of the contact corrosion test
setup developed for the investigation of chemical interactions of
ceramics with solid and semi-solid metals.
8.6 Bulk Ceramic Forming Toolsj287