TECHNOLOGY AREAS: Weapons; Sensors; Air Platform The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Develop 0-1500 F co-fired ceramic heat flux sensor as an alternative to 0-500 F sensors. DESCRIPTION: Schmidt-Boelter heat flux gauges are commonly used in aerospace testing to measure heat transfer at the surface of a test article, which is essential for the safety and performance of various components in in-flight systems. This gauge is often employed in testing and analyzing thermal protection systems, heat exchangers, and other areas where precise temperature readings are vital during dynamic operating conditions, such as ascent, re-entry, or extreme environments. Featuring a thin, thermocouple-like sensor that closely contacts the surface, the Schmidt-Boelter gauge provides accurate measurements of solid surfaces. Its rapid response time is precious in aerospace, where temperature fluctuations can occur swiftly due to changes in speed and atmospheric conditions. Additionally, these gauges are designed to withstand the harsh conditions typical of aerospace environments, ensuring reliable performance even in extreme temperatures and pressures. Their low thermal mass effectively captures transient heat transfer phenomena, making them indispensable in the analysis and optimization of thermal management systems. Overall, Schmidt-Boelter gauges are essential in aerospace engineering, offering precision and responsiveness for maintaining the integrity and functionality of aircraft and spacecraft components. Due to their current manufacturing limitations, small size, and intricate nature, these sensors are handcrafted one at a time, limiting their size, sensor-to-sensor accuracy and repeatability, and flexibility in applications that could be achieved with an automated process. Additionally, the current design limits the maximum usable temperature to 500 F. Further complicating the process, a sensor installed in a test article cannot typically be removed without destruction. Advanced ceramics manufacturing technology allows microelectronics features to be mass-produced at a micron scale. For these sensors, ceramics manufacturing processes could provide the consistency, performance, and temperature tolerance required for high-temperature co-fired device production. The ceramic refractory composite sintered at elevated temperatures in a carefully controlled atmosphere can provide a rugged substrate for selective metallization, precision drilling, and wire bonding needed for electrical connection of dissimilar metals. An advanced technique methodology is needed to revolutionize the manufacturing and operational capabilities of Schmidt-Boelter heat flux gauges by developing an automated production process that leverages the latest ceramics manufacturing techniques. The extended goals are: Temperature Enhancement: Increase the maximum usable temperature of the sensor from 500 F to at least 1500 F, utilizing bi-metallic thermopile designs and advanced ceramic refractory composites that can withstand extreme thermal environments. Automated Production: Transition from handcrafted sensor production to a fully automated manufacturing process. This will involve integrating precision ceramics manufacturing techniques to enable the mass production of heat flux gauges, significantly reducing production time and costs while maintaining high-quality standards. Consistency and Accuracy: Improve part-to-part consistency and sensor-to-sensor accuracy through uniform processing techniques, ensuring reliable measurements in diverse aerospace applications. This will foster greater confidence in test results and allow for more precise engineering decisions. Scalability and Flexibility: Develop a scalable manufacturing model that can accommodate various designs and specifications, allowing for customization to meet specific measurement needs across a wide range of aerospace testing scenarios. Enhanced Functionality: Explore and evaluate other innovative technologies alongside ceramics manufacturing that could further improve performance, durability, and functional range of heat flux sensors. This includes investigating alternative materials and designs that could complement the bi-metallic thermopile approach. These objectives aim to not only enhance the capability and reliability of Schmidt-Boelter heat flux gauges but also to set new standards in aerospace testing instrumentation, driving advancements in thermal management and energy efficiency. This will ultimately contribute to safer and more efficient aerospace systems, supporting the industry's ongoing evolution toward more sophisticated and resilient technologies. PHASE I: The Phase 1 effort should choose the optimum manufacturing process, design of sensing elements, manufacture of prototype sensing elements, testing of prototypes, and generation of a batch production plan that meets the sensor requirement specifications. The result of the Phase 1 effort will be a path forward for manufacturing and functionally testing complete sensors in batch quantities. PHASE II: The Phase II should fully develop the manufacturing process, manufacture batches of sensing elements, bonding to a sensor base, lead attachment, and calibration of sensors. In-situ demonstration testing in a relevant environment at the University of Tennessee Space Institute Propulsion Research Facility (operated by the Air Force) will provide performance characteristics and survivability data in comparison to current sensors. PHASE III DUAL USE APPLICATIONS: Phase III will involve detailed sensor characterization, applications optimization, manufacturing refinement to allow full-out marketing. REFERENCES: 1. How The Schmidt-Boelter Gage Really Works, C.T. Kidd et al, 1995. 2. Design Guidelines, AdTech Ceramics Inc., Chattanooga TN, AdTech Ceramics.com KEYWORDS: Heat flux; Schmidt-Boelter; ceramic sensor
