Development of a Low-Temperature, High-Performance Coating Process for Heat-Sensitive Substrates

To address the challenge of temperature rise control during the coating process for thermally sensitive substrates (e.g., epoxy adhesive-bonded structural components), this paper proposes a low-temperature electron beam evaporation coating process. Through a dynamic thermal management strategy featuring segmented deposition-cooling cycles, the performance of this process in terms of the core properties (i.e., stress, adhesion, and optical performance) of metallic reflective films-with silver films as the research subject-was systematically investigated, and the deposition process was optimized by integrating the thermal failure threshold of the epoxy adhesive. Experimental results demonstrate that under strictly controlled substrate temperature conditions, this process not only significantly reduces the residual stress of the reflective film, but also ensures that the interfacial adhesion meets the strictest Class 03 severity level specified in the national standard (GB/T 26332.4-2015/ISO 9211-4:2012), the average reflectivity in the visible wavelength range is comparable to that of the traditional continuous coating process (>99%@450−900 nm), and the substrate temperature rise remains consistently below the critical threshold of the epoxy adhesive. Through the synergistic effect of Ion-Assisted Deposition (IAD) and dielectric encapsulation, the oxidation resistance and environmental durability of the silver film are significantly improved, satisfying the long-term service requirements of aerospace optical devices under extreme multi-physics field coupled environments. Further theoretical analysis reveals that the thermal relaxation mechanisms and structural regulation principles of this process exhibit cross-scenario applicability, providing an innovative solution for high-performance coating of low-temperature-sensitive substrates that balances aerospace reliability and industrial universality.