铝基碳化硅表面活化与镍磷非晶膜制备

Aluminum-based silicon carbide is an attractive material for next-generation space optical mir⁃ rors because of its high specific stiffness and low density；however，surface alumina and multiphase interfa⁃ cial defects hinder the attainment of optical-grade surfaces. To meet the optical finishing requirements of aluminum-based silicon carbide mirrors，an electroless nickel-phosphorus amorphous film was deposited on aluminum-based silicon carbide substrates for surface modification. The deposition technology for an amorphous Ni-P film on aluminum-based silicon carbide（SiCp volume fraction：20%）was investigated using the process route of cleaning-primary zinc immersion-dezincification-zinc removal-secondary zinc im⁃ mersion-electroless nickel plating，with emphasis on oxide-film elimination，interface activation，enhance⁃ ment of interfacial bonding strength，and coating-thickness control. During primary zinc immersion，the surface oxide layer was partially removed via the formation of a friable reaction layer；however，the result⁃ ing activation layer was shallow and prone to peeling. Zinc nitrate dezincification effectively removed the reaction layer and exposed the substrate. Secondary zinc immersion enabled large-area，continuous activa⁃ tion，and an activation layer was also formed on the surfaces of silicon carbide particles. Consequently，the interfacial bonding strength was markedly improved relative to the untreated substrate. An L9 orthogonal design indicated that electroless plating time exerted the greatest influence on coating thickness，followed by secondary and primary zinc-immersion times. The optimal parameter set comprised 8 h electroless plat⁃ ing，10 s primary zinc immersion，and 2 min secondary zinc immersion，yielding a coating thickness of ap⁃ proximately 50-60 μm. The proposed process enhances coating density and interfacial bonding through stepwise activation and a crystal-cell stacking growth mechanism，providing an effective surface-modifica⁃ tion strategy for the high-stability requirements of space optical mirrors.