Heat & Corrosion Resistant Materials/Composites: Advancements in Electron Beam Melting and Coating
The biannual High Power Electron Beam Technology Conference is the single event devoted to this technology. Most recently held in 2004 in Reno, Nev., the conference brought together nearly 70 professionals active in the EB processing field to discuss and learn about the most recent advancements in the areas of EB melting and coating technology. Companies and organizations represented included ALD Vacuum Technologies, von Ardenne Anlagentechnik, Cabot Supermetals, Honeywell International, ATI Allvac, AlloyWorks LLC, Sandia National Laboratory, Spotts Stevens and McCoy Inc., Deutcher Elektronen Synchrotron, TIMET, Praxair Surface Treatment, National Academy of Science (Ukraine), Fraunhoffer Institute and Technical University Dresdner.
Melting and coating researchATI Allvac (Monroe, N.C.; www.allvac. com), an Allegheny Technologies company producing nickel-base and cobalt-base superalloys, titanium alloys and specialty steels for the aerospace industry, is involved in the U.S. Air Force Research Laboratory sponsored metals affordability initiative consortium program, which is aimed at achieving cost savings for EBCHM (electron beam cold hearth melting) Ti-6Al-4V processed slab ingots compared with standard double vacuum arc remelt (VAR) round ingot processing. The reduced costs of EBCHM are a direct result of the use of less costly input raw materials, higher melt rates and fewer melts and hot work processing steps, leading to improved yields. The EBCHM process is capable of producing chemically homogeneous Ti-6Al-4V ingots with no inclusions, and, according to AlloyWorks LLC (Salisbury, N.C.; www.alloyworks.com), a company involved with specialty metals-melting technology including near-net plasma cold hearth, VAR, continuous rod casting, and ESR (electroslag remelt), is the most cost-effective method to produce titanium alloys.
Researchers at Spotts Stevens and McCoy Inc. (Reading, Pa.; www.ssmgroup. com), an engineering and consulting firm serving business, industry and government for more than 70 years, and von Ardenne Anlagentechnik GmbH (Dresden, Germany; www.ardenne-at.de), an organization involved with the development of vacuum coating technologies for deposition of thin films by means of magnetron sputtering and electron beam evaporation, are evaluating greater use of residual gas analysis to monitor processes (Fig. 1) because of the need for process improvement and the fact that the cost of these instruments have dropped. The application of residual gas analysis now spans the range from troubleshooting to improving product quality and yields with electron beam heating processes in mind.
Researchers at von Ardenne Anlagen-tech-nik also are developing solutions for metal strip coating by means of an enhanced EBPVD concept (Fig. 2), as thin film application in metallurgical industries has seen extensive growth (Fig. 3). In addition to coating steel for corrosion protection, there is greater use of optical and catalytic coatings on diverse materials including stainless, copper and aluminum. Figure 4 illustrates industrial-scale PVD technologies for high-production coating lines. Special attention is being focused on industrially relevant production solutions for large systems with respect to adhesion, thermal load and layer thickness accuracy.
Electron beam physical vapor deposition thermal barrier coating (EBPVDTBC) implementation at Praxair Surface Treatment (PST, in Danbury, Conn.; www.praxair.com) is part of a program with General Electric Aircraft Engine (GEAE) aimed at meeting the challenge to provide high quality coating service for EBPVD thermal barrier coatings (Fig. 5). Research during the past six years has resulted in the optimization of the technology with regard to yield via continuous improvement driven by Six Sigma and Lean Manufacturing technology. Research is addressing the key factors for production quality throughput and improved yields.
ALD Vacuum Technologies GmbH (Hanau, Germany; www.ald-vt.com), a global supplier of processes and services in the field of vacuum process technology, also is involved in the development of new affordable technical solutions for turbine coatings. Figure 6 shows the chronology of coating systems currently in service.
Frauenhoffer Institute for Electron Beam Application Technology (Dresden, Germany; www.fep.fraunhofer.de) is involved with the development of surface modification and treatment using electron beams for microstructuring of large arc substrates. Research involves surveying the different physical effects related to electron beam interaction with matter and their use for micron-scale surface machining and process control. Research needs aimed at opening new applications and markets for the EB technology are being evaluated with particular emphasis on the field of microstructuring of large area substrates like solar cells and glass polarizers for display fabrication.
The Fraunhoffer Institute together with Dresdner University of Technology (Germany) and AIS Automation Dresden GmbH (www.ais-automation.com) also is involved in the development of an advanced process control system adaptable to any sort of PVD coating machine. An additional function of such a system is in situ parameter adaptation to minimize process fluctuation and troubleshooting. The system permits a new combination of precision and the highest productivity. The next conference will be held 22-24 October in Reno.
For more information: Robert Bakish is president of Bakish Materials Corp., 171 Sherwood Place, PO Box 148, Englewood, NJ 07631; tel: 201-567-5873; e-mail: email@example.com.
Additional related information may be found by searching for these (and other) key words/terms via BNP Media LINX at www.industrialheating.com: electron beam, EB, cold hearth melting, titanium melting, vacuum coating, strip coating, EBPVD, thermal barrier coating, TBC.