Advances in Industrial Energy-Efficiency Technologies
National Renewable Energy Laboratory
Buildings and Energy Systems Division
The National Renewable Energy Laboratory is a national laboratory of the U.S. Department of Energy.
NREL/TP-470-5776F
DE94006880
April 1994
NREL is the nation's premier renewable energy and energy efficiency laboratory. Located in Golden, Colorado, NREL is part of the Department of Energy's family of national laboratories. More than 735 staff members conduct or support research at NREL; this staff is augmented by 150 visiting scientists from industry and academia. Founded in 1977 at the Solar Energy Research Institute, NREL develops renewable energy technologies to:
Photo: A conventionally processed metallized ceramic circuit manufactured by Brush Wellman. This sample consists of a thin gold film bonded to a beryllium oxide substrate. [provided in source document]
America's automotive, computer, and telecommunication industries are built on advanced electronic components that employ metallized ceramics within their circuitry. Brush Wellman, a leading electronics/ceramics manufacturer, is turning to the sun to produce these ceramic materials. Brush Wellman has joined with the National Renewable Energy Laboratory (NREL) to metallize ceramics using highly concentrated solar radiation. The technique is being perfected under a cooperative research and development agreement (CRADA) between the two organizations [see the box on the back of source document]. Metallized ceramics are playing an increasingly important role in high-tech circuitry. These materials consist of a ceramic substrate with a thin layer of metal bonded to its surface; the substrate electrically insulates the conductive metal layer. Certain ceramics, such as beryllium oxide, draw heat away from surrounding components, making them ideal for use in high-temperature environments such as industrial power supplies and motor controls.
Preliminary results indicate that metallized ceramics manufactured using concentrated solar energy are higher in quality and less expensive than those manufactured using traditional methods.
Solar metallization of a ceramic substrate entails "painting" it with an organometallic material and then heating it to temperatures high enough to drive off the organic portion of the paint. The metal portion remains behind and bonds to the ceramic base.
NREL and Brush Wellman are using highly concentrated solar energy - known as solar flux - as the source of heat in the metallization process. The high solar flux is produced by NREL's solar furnace [described in the box on the back of source document]. The flux heats only the surface of the material; the bulk of the ceramic substrate remains unaffected. The solar process produces a uniform, high-quality bonded metal coat.
Solar metallization is efficient and inexpensive. Conventional processes, such as those using arc lamps, lasers, and tube furnaces, are only 5% to 10% efficient and deliver energy at a minimum of $0.86 to $1.72/kWh. The solar process is more than 90% efficient and delivers energy at $0.44 to $0.70/kWh. The process is also environmentally benign; fossil fuels are not required to power the process, and waste streams are minimal. Solar metallization can easily be scaled up to industrial power levels. In fact, solar furnaces that deliver megawatts of power are operating today.
The CRADA between NREL and Brush Wellman is determining the feasibility of the high-flux metallization process. Researchers are metallizing beryllia and alumina ceramic substrates with thin films of copper, palladium, platinum, and gold. This work should lead to a pilot-scale, solar metallization manufacturing plant.
Highly concentrated solar flux has characteristics that are well suited to surface modification processes; high temperatures, rapid rates of heating, and energy from the entire solar spectrum are available and readily controlled in a solar furnace. In addition to metallization, NREL researchers are exploring other surface high-solar-flux processes, such as cladding, surface hardening of steel, and chemical vapor deposition. The technical, economic, and environmental benefits that high solar flux brings to metallization also apply to these surface processes. We may find, as we enter the next century, that solar energy will help America's advanced material industry maintain its competitive edge.
NREL's High-Flux Solar Furnace uses a series of mirrors to concentrate sunlight into an intense focused beam. The large, flat mirror - called a heliostat - tracks the sun and reflects the light onto the 25 curved facets that collectively make up the primary concentrator. The curvature of the primary concentrator focuses the light to a 10-centimeter-diameter circle inside the test facility. Under optimal conditions, the focused beam is 2500 times the intensity of normal sunlight.
Built in 1990, NREL's High-Flux Solar Furnace is the state of the art in solar furnace technology. The furnace's long focal length and its off-axis design give researchers experimental flexibility and a high level of control over the incoming light. The custom-designed surfaces of the heliostat and the primary concentrator reflect radiation from the entire solar spectrum (300 to 2500 nanometers).
Photo: The High-Flux Solar Furnace at the National Renewable Energy Laboratory. Top: the actual facility in Golden, Colorado. Bottom: an artist's conception. [provided in source document]
A cooperative research and development agreement - or CRADA - is a research partnership between a federal research institution and a private company. CRADAs are designed to make U.S. industry more competitive and protect our economic security. They bring together complementary expertise, resources, and facilities from government and industry. Private partners benefit from reduced research costs and the retention of intellectual property rights, while the government and society benefit from the wide range of technical advances resulting from these agreements.
Contact:
Allan Lewandowski
National Renewable Energy Laboratory
1617 Cole Boulevard
Golden, Colorado 80401-3393
(303) 231-7000 ext. 1972
Last Updated: February 12, 1996