Coatings that Survive up to 1000° C
R&D efforts for a U.S. Navy Phase 2 SBIR addressed coating requirements for the inside of a missile dome. This included robust, broadband antireflection (BBAR) coatings for the 3-5 µm spectral range along with extremely high temperature operation and survivability. PPC's IBS technique solved the challenging variable-thickness requirement by utilizing shadow masking to control coating uniformity. Using our inhouse developed VirtualChamber™ 3-D coating simulation tool, we were able to predict the proper mask shape, allowing us to to simulate and coat a variety of non-uniform, spatially-varying coatings. Results demonstrated proper spectral transmission (coating thickness profile) for the dome, and operational survivability to 1000° C!
Optical Coatings for
Deep Concave Surface
NEED & CUSTOMER REQUIREMENT
Need: Hypersonic missiles have numerous advantages but require new dome shapes, such as the tangent ogive, rather than hemispheres. These domes require more specialized coatings than hemispheres, with much higher performance.
Value to the Warfighter: Hypersonic missiles are faster, have relatively longer range, have improved aerodynamics, and operate at lower temperatures for improved infrared imaging. High performance optical coatings are a key enabler for these missiles.
Operational Gap: Currently, hemispherical domes use low performance coatings where the imperfections of the coatings are 'baked in' to the requirements. This will not be acceptable for hypersonic missiles, where a specific spatially-varying coating thickness profile is required.
Customer Specifications: Wide angular range of operation or field of regard;
Operational temperature ~1000° C;
Withstand thermal shock conditions upon missile acceleration;
Durability of external coating to rain/sand/etc. micro-impacts and general environmental survivability;
Operational over the 3-5um mid-wave IR spectral band.
Technology Description: PPC uses precision shadow masking to create the necessary spatially-varying coating thickness profile, during the ion beam sputtering process that generates the coating. These coatings survive to at least 1000° C.
TECHNOLOGY DEVELOPMENT MILESTONES (SBIR/STTR)
| Milestone | TRL | Risk | Measure of Success | TRL Date |
| High temp performance | 4 | Moderate | 1000° C survival verified | Feb 2010 |
| Correct spatially-varying thickness profile | 4 | Low | Verification using a 'mock-up' tangent ogive done | Oct 2011 |
| Fully functional AR coating (oxides) for dome interior | 4 | Low | Verification using a 'mock-up' tangent ogive done | Dec 2011 |
| Optical quality sputtered nitride coatings demonstrated | 3 | Moderate | Optical density, transparency | Feb 2012 |
TECHNOLOGY TRANSITION OPPORTUNITIES (PHASE III)
Other Potential Applications: In addition to the coating for hypersonic missile domes, PPC has developed novel materials for optical coatings in the MWIR spectral region. These combine excellent IR transmission, durability, and thermal conductivity, making them ideal for missile domes and other critical military applications. Secondary markets for this technology fall into 8 major categories: (1) Intelligence, Surveillance, and Reconnaissance windows and domes, (2) optics for chemical and biological agent detection, (3) optics for infrared countermeasures, (4) medical diagnostic applications, (5) trace gas sensing, (6) scientific optics/materials science, (7) large, high performance optics, and (8) heat-resistant coatings.
Business Model: PPC plans to become the premier supplier of high performance MWIR optical coatings, beginning with the missile dome, IRCM, and ISR markets. Developmental funds from industrial and military customers/partners will fuel the transition from research prototypes to commercial devices. PPC may require additional funding for a dedicated coating chamber optimized for the unique/novel coating processes.
Objective: PPC's coatings have proven performance that exceeds other coating methodologies. The performance advantages are highlighted with hypersonic missile domes, but are broad-based and can be used in virtually any high performance infrared application. Our goal is to displace inferior coatings for a significant fraction of these infrared applcations, by demonstrating to the primes that this technology solves numerous historical challenges with optical coatings.