Transparent Oxynitride Coatings for High Speed Missile Applications

Preliminary work on thin films of silicon-carbon-oxy-nitride (aka SiCON) by ion-beam sputtering (IBS) has suggested the potential of this material for high-speed missile window application. Surmet Corporation proposes to use an innovative plasma depositiontechnique to demonstrate fabrication of SiCON materials with improved optical transmission, hardness and strength for IR window applications. High rate of material deposition and ease of manipulating the process variables, make Surmet's proposed processsuitable for the deposition of substantially thick films with precisely controlled chemistry. Also, unlike IBS it does not require sputtering targets with tailored chemistry. For this research, thin IBS deposited films of both Si-C-N and SiCON will becharacterized and used as a baseline for subsequent deposition experiments using Surmet's process to produce materials with characteristics similar to films produced using IBS. The Surmet fabricated films will then be characterized with a focus on opticaland mechanical properties to determine the composition best suited for erosion resistant infrared (IR) coatings application. Phase I results and consultation with the DARPA program manager will allow defining a Phase II research proposal for furtherdevelopment of SiCON either as a coating or a bulk material for high-speed IR missile windows applications. It is anticipated that free-standing bulk materials of SiCON (~200 mm) with desirable properties can be fabricated using Surmet's innovativedeposition process. The proposed research effort to develop SiCON in the form of coating and/or bulk materials with improved properties for infrared (IR) optical applications in high-speed missile windows will be of significant technological andcommercial value. The Phase I feasibility demonstration will help guide a future Phase II research for the synthesis and processing of bulk SiCON materials and its commercialization.