Abstract:
Al-12% Si is the commercial alloy commonly used to make pistons by using gravity casting method. When
this alloy was modified with Ni, Cu, and Mg (modified alloy), it showed an adequate fluidity during casting
and achieved higher strength. However, the addition of alloying elements reduces its thermal characteristics. Therefore, an attempt has been made to improve the thermal conductivity through modifying the
microstructure. It was done by changing the cast method to squeeze cast, adding 0.04%Sr (Sr-modified
alloy) and post-heat treatment (T6 and T7). Results highlighted that the sample of gravity cast-Sr-modified
alloy showed enhancement in thermal conductivity. Even though squeeze cast-Sr-modified alloy showed
reduction in thermal conductivity of few percentage, it possessed better strength, however the heat
treatment (T7 condition) showed a noticeable increment in thermal conductivity. Therefore, it is concluded that T7-heat-treated squeeze cast-Sr-modified alloy showed an excellent combination of strength
and thermal conductivity making it an ideal material for piston applications. The piston component was
studied by numerical steady state thermal analysis using ANSYS Workbench, obtained a maximum heat
flux of 1.80 W/mm2 for Al-Si piston alloy aged for 11 h (T7), which is in agreement with the experimental
results.
