钢材表面处理方式对耐中温憎水涂料性能影响研究

Study on the Influence of Surface Treatment on the Properties of Medium Temperature Hydrophobic Coatings

摘要:

现役航空发动机在服役过程中，由于后端机匣等部件内外表面温度可达400 ℃，因此对部件涂层的耐热及憎水性提出更高的要求。当部件的憎水涂层耐温性低于400 ℃时，不仅会引起涂层烧蚀或者熔融，留下黄色和黑灰色等复杂颜色而影响外观，还会降低其耐蚀性能而引起零件锈蚀，导致在维修过程中难以分清原基体材料情况（是否存在裂纹、凹坑等缺陷），而造成更大的困扰。目前，在国内尽管中温段憎水涂料的研究取得一些成果，但主要是聚焦于单纯的憎水涂料的研制。众所周知，涂料的防护性能除了与涂料本身有关外，还取决于零件的表面处理。由于涂料涂覆之前部件采用何种处理方式的研究涉及较少，因此以发动机零件常用的1Cr11Ni2W2MoV基材为研究对象，研究磷化、镀Zn、镀Cu、镀Ag表面处理方式对耐中温憎水涂层体系的宏微观形貌、电化学及耐环境等性能的影响规律。结果表明：4种表面处理方式的镀Ag与耐中温憎水涂料配合最佳，涂层表面光滑（粗糙度Ra约1.2 μm）、水接触角约120°、耐中性盐雾寿命约576 h，即使在300和400 ℃环境中处理1 h，该涂层的接触角仅降低10°左右、耐中性盐雾性能也依然保持在576 h左右。说明，4种表面处理方式中电镀Ag/耐中温憎水涂层最为稳定、配合效果最佳，可用作航空发动机的中温段受热部件（如发动机后端壳体、紧固件及其他部件）的表面防护层。该研究在生产应用单位具有较高的工程价值。

Abstract:

The temperature of the back-end casing of the current aero-engine can reach 400℃， where the coating has higher requirements for heat resistance and hydrophobicity. If the temperature resistance of the hydrophobic coating is lower than 400 ℃， the coating will be ablated or melted， leaving behind complex colors such as yellow， black and gray， which not only cause poor appearance， but also poor anti-corrosion performance， and lead to rust of parts after a long time. In the maintenance process， it is also difficult to distinguish the original matrix material （cracks， pits and other defects） and cause greater trouble. Currently， China has made some progress in the field of water-repellent coatings in the middle temperature segment， but mainly in the development of water-repellent coatings materials. As we know， in addition to improving coatings， other significant factors in the field of coating protection， such as the surface treatment of parts. But the research on how to treat parts before coating is still limited， usually the surface treatment of parts isn’t the focus of research papers. However， this is precisely the content of the factory of aero-engine and application units. Therefore， this study took 1Cr11Ni2W2MoV substrate as the research object in engine parts， and then the effect of four surface treatments on the macro and micro morphology， electrochemical and environmental resistance of the medium-temperature hydrophobic coating system was studied. The results show that Ag plating has the best match with the medium temperature resistant water-repellent coating among the four surface treatments， photostatting， Zn plating， Cu plating and Ag plating. The surface of Ag plating coating system is smooth （roughness Ra is about 1.2 μm）， the water contact angle is about 120°， and the life of neutral salt spray resistance is about 576 h. The contact angle of the coating is only reduced by about 10°， and the resistance to neutral salt spray is still maintained at about 576 h even the coating has experienced 300 ℃ （1 h） and 400 ℃ （1 h）， indicating that the system of Ag plating/medium temperature resistant hydrophobic coating is relatively stable. Therefore， electroplating Ag/medium temperature resistance hydrophobic coating has the best effect among the four surface treatment methods in this study， which can be considered as the surface protection of the heated parts， such as the rear end shell of the engine， fasteners and other parts， and this system has high engineering value in the application unit.