Weather Resistant Aluminum Mirrors With Enhanced Uv Reflectance

We report on the development of front surface aluminum mirrors with dense, dielectric overcoats deposited by low-voltage reactive ion plating (RLVIP) for potential use in gas phase solar detoxification of hazardous waste. The mirror coatings ideally should have a reflectance of \u3e 90% in the spectral band of 300 - 400 nm, what has not yet been achieved because of some absorption in the dielectric overcoat. However, the dielectric thin films have a vitreous-ceramic type microstructure and provide extended service lifetime of the aluminum mirrors in outdoor weathering conditions, as compared to conventional protected front surface aluminum mirrors. Coating samples have been subjected to accelerated weathering in the lab, and real-time outdoor weathering. We present details of the thin film deposition process used and our first results of extended exposure testing of select ion plated samples