Study on AZ91D chip for injection molding (2nd Report, Effect of dimension on effective thermal conductivity after consolidation)

Abstract

The purpose of this study is to propose an effective model to estimate the effective thermal conductivity of compacts made from magnesium alloy particles, considering the effects of particle size, temperature and pressure. In order to investigate the influence of the particle size, six kinds of particles were prepared in which the cross sectional area was different. The test particles made from AZ91D were poured into a compression vessel and then a given pressure was applied to the piston of vessel for six hours under constant temperature condition. After compression, effective thermal conductivity of compacts were measured by steady state comparative-longitudinal heat flow method. The numerical calculation considering two-dimensional steady heat conduction was also conducted by using the actual cross section of compacts. Test results showed that the effective thermal conductivity of compacts were increased with increase of applied pressure and temperature elevation. Calculation results also revealed that by considering the actual cross section of compacts, the effective thermal conductivity could be well estimated when filling fraction is lower than 0.8. However, when filling fraction is exceed 0.8, the effect of thermal contact resistance between particles on thermal conductivity is not negligible. The experimental equation of effective thermal conductivity of compacts was determined to discuss the effects of cross sectional area of particles.

Keywords

• effective thermal conductivity
• filling fraction
• magnesium alloy
• thixomolding