Vice president, Research and Development, Telic Co., Santa Monica, Calif.
Pages: 16 Published: Jan 1983
The recent development of magnetron sputtering technology has made this coating method applicable to large substrate areas and therefore to selective absorber applications. This paper describes work conducted at our laboratory to investigate the application of magnetron sputtering for depositing selective coatings for both low-temperature and high-temperature collectors. The coatings incorporate metal, oxide, and cermet materials arranged into various combinations of discrete and graded layers. Both d-c reactive sputtering and direct r-f sputtering from oxide and cermet targets have been investigated. The materials have ranged from stainless steel reactively sputtered in carbon monoxide, to cermets formed by cosputtering from alumina (Al2O3) and platinum targets. Coatings on flat plate substrates of glass and stainless steel are described. The coatings typically yield solar absorptance values of greater than 0.90 with room temperature emittances of less than 0.10. Of particular interest are (1) reactive-sputtered multilayer metaloxide coatings, which have thermal stabilities comparable to those of electroplated black chrome (300 to 400 °C in air) and show promise for application in low-cost collectors, and (2) Pt-Al2O3 cermet coatings that are stable at 600 °C in air and applicable to medium and high temperature collectors.
steels, microstructure, solar energy, coatings, surfaces, selective absorber, vacuum deposition, sputtering
Paper ID: STP31776S