Versatile and Rapid Plasma Heating Device for Steel and Aluminum

The main objective of the research was to enhance steel and aluminum manufacturing with the development of a new plasma RPD device. During the project (1) plasma devices were manufactured (2) testing for the two metals were carried out and (3) market development strategies were explored. Bayzi Corporation has invented a Rapid Plasma Device (RPD) which produces plasma, comprising of a mixture of ionized gas and free electrons. The ions, when they hit a conducting surface, deposit heat in addition to the convective heat. Two generic models called the RPD-Al and RPD-S have been developed for the aluminum market and the steel market. Aluminum melting rates increased to as high as 12.7 g/s compared to 3 g/s of the current industrial practice. The RPD melting furnace operated at higher energy efficiency of 65% unlike most industrial processes operating in the range of 13 to 50%. The RPD aluminum melting furnace produced environment friendly cleaner melts with less than 1% dross. Dross is the residue in the furnace after the melt is poured out. Cast ingots were extremely clean and shining. Current practices produce dross in the range of 3 to 12%. The RPD furnace uses very low power ~0.2 kWh/Lb to melt aluminum. RPDs operate in one atmosphere using ambient air to produce plasma while the conventional systems use expensive gases like argon, or helium in air-tight chambers. RPDs are easy to operate and do not need intensive capital investment. Narrow beam, as well as wide area plasma have been developed for different applications. An RPD was developed for thermal treatments of steels. Two different applications have been pursued. Industrial air hardening steel knife edges were subjected to plasma beam hardening. Hardness, as measured, indicated uniform distribution without any distortion. The biggest advantage with this method is that the whole part need not be heated in a furnace which will lead to oxidation and distortion. No conventional process will offer localized hardening. The RPD has a great potential for heat treating surgical knives and tools. Unavailability of the full amount of the DOE award prevented further development of this exciting technology. Significant progress was made during the 5th quarter, specially the invention of the wider-area plasma and the resultant benefits in terms of rapid melting of aluminum and thermal treatments of larger size steel parts. Coating of nickel base superalloys was demonstrated (an additional task over that proposed). Directed low cost surface enhancement of steel and the directed clean low dross energy efficient melting of aluminum are industrial needs that require new technologies. These are large volume markets which can benefit from energy savings. Estimated energy savings are very large, in the order of 1015 J/year when the equipment is universally used. Compact and directed heating technology/product market in these two sectors could potentially reach over $1B in sales. The results of the research, presented at the DOE annual Review meeting on Aluminum held at the Oak Ridge National Laboratory during the 4-5 October 2005, were very well received by the delegates and panel reviewers. Insufficient DOE funds to fully fund the project at the end of the 5th quarter necessitated some key tasks being only partially completed