9532072 Groza In the prior NSF funded research, the investigators have demonstrated that metals and ceramics powders can be rapidly consolidated to very high density by applying electric fields as well as pressure in a specified manner. The process is termed "Plasma Activated Sintering." The underlying hypothesis is that electric discharge creates plasma between particles causing local changes on the surface which facilitates the rapid sintering in the subsequent resistant heating under pressure. However, the exact mechanism has not been verified. In the current research, the investigators will use fiber optics to see whether there is indeed plasma between particles. The role of electric field will be studied since the process appears to work on both highly conductive metals (nickel) as well as less conductive ceramics (aluminum oxide). While prior work has suggested atomic level interfacial bonding with clean oxide free grain boundaries in aluminum nitride, what is going on at the particle surface has not yet been understood. The research will also include developing and verifying sintering models under field assisted consolidation. The resultant microstructures will be correlated to the process to develop controls needed to make useful parts from powder materials. Powder consolidation is central to the manufacture of several classes of advanced structural ceramics as well as many powder metal parts used in the industry. Starting from very fine powders is the desired approach to maximize the material properties. However, in processing fine powders, elimination of pores between particles is very difficult without losing the intrinsic advantage of the starting fine particle size. Since pores weaken the parts, any process such as the one described here which can rapidly consolidate the powders offers a new manufacturing avenue. This research will lay the foundation for the necessary large scale equipment needed for the process to be scaled up from the research stage to deve lopment and final commercialization. Several industrial powder processing manufactures have shown interest in this novel process.
