The primary experimental physical vapor deposition (PVD) facilities utilized by IPML researchers are the two Directed Vapor Deposition (DVD) systems developed during the 1990's and patented in 1996. Each of these PVD systems utilizes an electron-beam (e-beam) gun to vaporize materials. However, Directed Vapor Deposition is not standard e-beam evaporation. The DVD guns are not typical "pocket" evaporators or large multihundred kilowatt hearth melt refining systems. Instead both systems use specially modified axial welding type guns that allow DVD to make a significant departure from conventional e-beam evaporation. Instead of creating atomistic vapor in high vacuum (10-8 - 10-4 Torr) the DVD method uses an e-beam (10 kW) in a low vacuum environment (~10-3 - 10 Torr) where it is possible to entrain the evaporant in a carrier gas jet for focussed, efficient deposition. More information about the  technology can be found in the patent listed above and in various publications in the literature.

DVD technology was originally envisioned as a vapor processing method which would allow continuous fiber reinforcement for metal matrix composites to be coated rapidly, cleanly, and efficiently with various pure elements, compounds, or alloys. After coating individual fibers with material in the DVD system, the individual fibers (~100 mm in diameter) could then be  consolidated into a load bearing material using  equipment such as a hot isostatic press (HIP). Completed research suggests that DVD technology possesses certain advantages over traditional techniques when used to coat fibers. 

A significant portion of the original DVD experimental and modeling research was dedicated to developing an understanding of the fundamental material processing characteristics of this unique technology.  Although these basic studies continue, DVD researchers have more recently harnessed understanding of the technology to construct a  second generation  system and to synthesize thermal barrier coatings (TBCs), a material system application where DVD technology appears to hold particular promise. Construction of the second generation DVD system was funded in 1998 and 1999 by the Office of Naval Research (ONR) under the federal government's Defense University Research Instrumentation Program (DURIP). This second generation system (DVD II) allows more sophisticated processing to be conducted than is possible in the original system. It is being used to provide experimental data against which to verify modeling results generated at IPML, and it will act as a second platform upon which to perform application-based experimental research.

Directed Vapor Deposition II

The second DVD system was developed by the University of Virginia in cooperation with the Fraunhofer Institute for Electron Beam and Plasma Technology (Dresden, Germany). DVD II combines sophisticated low vacuum electron beam (e-beam) evaporation with vapor transport in a flowing gas stream. Use of the gas stream enhances material utilization efficiency and deposition rate. Use of the stream also allows different elements to be evaporated from closely neighboring sources. When evaporated simultaneously, the elements can form precise alloys. When evaporated sequentially, they can form multilayers. Within DVD II the gas and vapor stream can be plasma activated and attracted to an electrically biased coating surface. The technique’s innovative combination of e-beam evaporation, carrier gas transport, plasma activation, and biasing opens up new possibilities for the creation of desirable film structures and compositions.

The second Directed Vapor Deposition system has the ability to evaporate simultaneously from four small crucible sources, making possible alloy mixing or rapid multilayer creation.

There are certainly many unanswered questions about the ability of plasma-assisted DVD to create useful engineered film structures. However, research and development partners are being actively sought who will assist in the evaluation of DVD’s suitability for the creation of thick and thin film structures in numerous existing and emerging market applications. With continued research and development effort, plasma assisted DVD has an opportunity to contribute to the welfare of society through the creation of beneficial engineered film products.

If you have questions about our Directed Vapor Deposition (DVD) facilities, please send e-mail to Haydn Wadley.

Plasma-assisted Directed Vapor Deposition in action.

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