Thermal Issues in Materials Processing

This paper considers the thermal aspects that frequently arise in practical materials processing systems. Important issues such as feasibility, product quality, and production rate have a thermal basis in many cases and are discussed. Complexities such as property variations, complex regions, combined transport mechanisms, chemical reactions, combined heat and mass transfer, and intricate boundary conditions are often encountered in the transport phenomena underlying important practical processes. The basic approaches that may be adopted in order to study such processes are discussed. The link between the basic thermal process and the resulting product is particularly critical in materials processing. The computational difficulties that result from the non-Newtonian behavior of the fluid, free surface flow, moving boundaries, and imposition of appropriate boundary conditions are important in several processes and are discussed. Some of the important techniques that have been developed to treat these problems are presented, along with typical results for a few important processes. Validation of the model is a particularly important aspect and is discussed in terms of existing results, as well as development of experimental arrangements to provide inputs for satisfactory validation. The importance of experimentation and linking the micro/nanoscale transport processes with conditions and systems at the macroscale are discussed. Future trends and research needs, particularly with respect to new materials and new processes, are also outlined.