COATED ARTICLES HAVING A PROTECTIVE COATING

摘要

An article includes a substrate, a functional coating deposited over the substrate, and a protective coating deposited over the functional coating. The functional coating and the protective coating define a coating stack. The protective coating provides the coating stack with an emissivity value higher than the emissivity value of the functional coating alone. The protective coating can have a thickness in the range of greater than 100 Å to less than or equal to 10 microns and a refractive index in the range of 1.4 to 2. The protective coating can include a first layer formed over the functional coating and a second layer formed over the first layer. The first layer can include 50 wt. % to 100 wt. % alumina and 50 wt. % to 0 wt. % silica, and the second layer can include 50 wt. % to 100 wt. % silica and 50 wt. % to 0 wt. % alumina. An alternating current power supply and cathode target system includes a cathode target including aluminum in the range of 5 wt. % to 100 wt. % and silicon in the range of 0 wt. % to 95 wt. %.