Advanced Thermal Management for Directed Energy Weapons: Durable, High K Plasma Electrolytic Oxidation Coating applied to Friction Stir Welded Cold Plate

Thermal Management Systems (TMS) are essential for Directed Energy Weapons (DEWs) to expel generated heat and prevent overheating that risks damage and weapon failure. A key part of the TMS is the cold plate, which cools electronics by circulating coolant through internal channels in a closed-loop system.Recent two-phase cold-plate designs offer distinct advantages over traditional copper tube and single-phase designs. In two-phase designs, the refrigerant undergoes phase change as it absorbs heat, and uniform evaporation maintains consistent temperature throughout (within a few degrees). This temperature uniformity is critical for maintaining laser wavelength emission in DEWs.Despite the benefits of two-phase design, implementation is limited by manufacturing methods. Conventional methods, such as copper tube, gun drilling, and vacuum brazing, each impose significant design constraints and suffer from poor production yield and repeatability.Another key challenge is the thermal interface between the cold plate and electronics.  Traditional thermal interface materials (TIMs) like thermal pads, paste, and solder limit performance with low thermal conductivity, insufficient dielectric strength and poor durability.To address these issues, IBC Materials (IBC) proposes a next-generation solution that implements: (1) friction stir welding (FSW) to improve design and manufacture of cold plates and (2) plasma electrolytic oxidation (PEO) coating to improve thermal interface. FSW is a scalable, high-integrity solid-state welding process that enables manufacture of customizable cooling channel configurations for high-performance two-phase cold plates. Manufacturing and FSW are vertically integrated, conducted using a single platform developed by IBC. PEO is a thin, thermally conductive ceramic-based dielectric layer applied directly onto the cold plate by a tank immersion coating process. PEO simultaneously offers good thermal conductivity and electrical insulation, making it uniquely suited as a direct interface between electronics and metal heat sinks. PEO is also resistant to thermal shock, wear, scratch, and corrosion damage, making it ideal for field deployment. Mounting electronics directly to PEO-coated cold plates could provide a disruptive improvement requiring changes to conventional designs. This improvement will be of great value for future designs. For existing designs, PEO may provide a crucial near-term TIM solution. IBC will investigate PEO on cold plates as an option parallel to FSW manufacturing.   IBC will work with University of Illinois Urbana-Champaign (UIUC) and Huntington Ingalls Industries (HII) to develop and characterize cold plates manufactured with FSW. The project will progress from thermal simulation and design work to fabrication of sub-scale and finally full-scale cold plates. PEO coating will be optimized as a dielectric thermal interface and evaluated on surrogate test boards as a proof of concept.