SBIR Phase I: A Superior Corrosion Resistant Undercoating for Vapor Deposited Hard Coatings

This Small Business Innovation Research (SBIR) Phase I project will develop a new type of corrosion resistant undercoating for application to metal substrates prior to the deposition of a hard decorative top coat applied by physical vapor deposition (PVD). PVD metal nitride coatings such as TiN and ZrN are extremely hard, and thus provide excellent scratch and wear resistance. However, they do not provide adequate corrosion resistance because of micron-scale flaws that act as corrosion sites, and thus a corrosion-resistant underlayer is needed. This undercoat must be smooth, sufficiently hard to support the hard PVD coating, and provide good adhesion to both the substrate and to the PVD coating. Ideally, the undercoat would provide a leveling effect to minimize polishing of the metal substrate. Recently, a new method for coating metal with a thin layer of glass has been developed. This coating, which is being optimized as a protective outer coating for polished aluminum, has many of the attributes of a successful PVD undercoating including corrosion resistance, hardness, and leveling. The key technological step will be to develop good adhesion between this glass coating and a PVD coating, and that will be the main focus of the proposed research. PVD coatings are widely used for applications that require both durability and an attractive appearance; for example, metal-nitride coatings can be made to closely resemble polished metals including brass, gold, and chrome. Current applications include personal items (pens, glasses, watches, jewelry, etc.), door hardware, plumbing fixtures, decorative trim on automobiles, and architectural detailing. All these PVD applications require an undercoating to improve corrosion resistance, but current undercoating options are inadequate for a number of reasons such as cost and environmental impact. Electroplating, the most widely used undercoating, uses significant amounts of toxic chemicals. A new type of undercoating which could meet performance and cost requirements while being environmentally friendly would thus have significant and immediate market potential.