HEAT TRANSFER OF 316L – A356 INTERPENETRATING HYBRID MATERIALS

Rising global temperatures and more frequent extreme weather events as a result of climate change have caused countries to tighten sources of emissions from all sectors, most notably in transportation. Regulations, in the form of fuel economy mandates and removal of internal combustion engine vehicles from city centers, have forced automotive companies to increase the efficiency of the powertrains in the products they sell to consumers. In seeking higher efficiencies - whether for internal combustion engines or in fully electrified powertrains - automotive companies are demanding more from the materials they use. Alloying, as in other industries, has been relied on to deliver new levels of performance; however, the incremental improvements from alloying often trail the rate of technological progress desired. Hybrid materials - a class of materials that are a combination of 2 or more monolithic materials to form one single "material" - offer an opportunity to hasten the time to achieve a collection of properties desired. In combustion applications, mechanical performance and heat transfer are critical to the overall powertrain efficiency. Despite the knowledge of hybrid materials, there exist few tools to understand the heat transfer within hybrid materials in applications where mechanical performance and heat transfer are critical. The study aims to show the heat transfer of an interpenetrating hybrid material using an experiment developed for monolithic materials joined with a thermal simulation to understand where 1-dimensional assumptions break down. The heat transfer within the hybrid material will reveal a complex interaction of the bonding between the material combinations and their geometry: 1. Initial work developed a two-step process to produce metal-metal hybrid materials of varying volume fractions of 316L stainless steel and A356 - an aluminum-silicon alloy. The hybrid materials were characterized for compressive, tensile, thermal conductivity and diffusivity, and porosity. 2. The final work used the flash disk method to calculate the apparent thermal diffusivity through the samples. These values were then compared to a heat transfer finite element model of the different volume fraction hybrids. The results were then compared to the effects of the porosity within the samples, contact conductance, and breakdown of 1D heat transfer assumptions.

Portions of this document were previously published in the Journal of Materials and Design, the section has been marked as such with accompanying information of the contribution from the student.