Corrosion Mitigation Coatings for RF Sources and Components

Abstract

RF sources are used in many applications, including high-power radar, communications, cancer therapy and diagnosis, electronic countermeasures, and high-energy accelerators. Many of these sources are located in well controlled environments where high-quality coolant fluids are readily available. Others, however, are located on platforms where harsh environmental conditions exist, and high-quality coolants are not easily provided. This includes ships at sea and remote transmitters in the second-world and third-world countries. Corrosive ethylene glycol mixtures may be required where extreme temperatures are encountered. Essentially, all high-power RF sources are fabricated from brazed copper structures, which are particularly susceptible to corrosion from corrosive coolants. This paper demonstrates using atomic layer deposition (ALD) to deposit nanometer-scale ceramic coatings inside coolant passages to separate the coolant from the underlying metal surface. This effectively reduces or eliminates corrosion and erosion, thereby increasing lifetime and reliability of RF sources. We describe ALD equipment and process specifically focused on RF sources and related components. The results of numerous experiments are reported, confirming the efficacy of the technology.