Study On Preparation Of Anticorrosive Coating On Aluminum Alloy Surface And Application Of Stress Corrosion

Aluminum alloy is widely used in the aerospace industry due to its excellent physical properties and relatively good corrosion resistance and fatigue resistance.However,it is prone to pitting corrosion and stress corrosion cracking（SCC）behaviors in typical service environments such as marine environments,resulting in structural damage and failure.Coating is a commonly used and effective method in the surface protection technology of aviation materials.Compared with traditional coatings（chromate,phosphate）,the new intelligent anti-corrosion coating can self-repair for internal and external damage,and is highly efficient,durable,and environmentally friendly.Advantages,its development and application are becoming a research hotspot in the surface protection of aviation metal materials.Therefore,the development of a high corrosion resistance,self-repairing and environmentally friendly membrane on the surface of aluminum alloy is of great significance for the safety and economic maintenance of aerospace structures.Firstly,the Ce-ZSM-5 self-healing membrane was prepared on the surface of 2024aluminum alloy by"Hydrothermal crystallization-ion exchange-hot pressing method".Study the effects of hot pressing time（10 minutes,15 minutes,20 minutes）,hot pressing temperature（80°C,90°C,100°C）and silane concentration（3%,5%,7%）on the performance of Ce-ZSM-5 self-healing membrane,and explore the best preparation process.The results show that when the hot pressing time is 15 minutes,the hot pressing temperature is 90℃,and the silane concentration is 5%,the Ce-ZSM-5 self-healing membrane with the best corrosion resistance can be obtained.Secondly,an electrochemical workstation and Zeiss microscope were used to study the corrosion resistance and surface morphology of the Ce-ZSM-5 self-healing membrane on the surface of 2024 aluminum alloy during the static corrosion process.The self-healing performance and mechanism of the membrane were studied by combining micro-area electrochemical technology and three-dimensional video microscope.The results show that the Ce-ZSM-5 self-healing membrane has excellent self-healing properties,and can still effectively protect the aluminum alloy for a long time when it is corroded for more than 21days.When the film is damaged,Ce³⁺is released,forming a protective film on the surface of the aluminum alloy,inhibiting the corrosion activity.Finally,the self-healing performance and mechanism of Ce-ZSM-5 self-healing membrane on the surface of 2024 aluminum alloy and 6061 aluminum alloy during the stress corrosion process were studied by using the in-situ analysis method of electrochemical impedance spectroscopy（EIS）and digital image correlation technology（DIC）.The results show that:for 2024 aluminum alloy,crack initiation begins at 1.5 hours,and cracks begin to accelerate at 6 hours;for 6061 aluminum alloy,cracks begin to initiate at 0.5 hours,and cracks begin to accelerate at 3.5 hours.In the initial stage of stress corrosion,a dense and continuous anti-corrosion film is formed on the surface of the aluminum alloy,which effectively prevents chloride ions from entering the metal matrix.As time goes by,the corrosion-inhibiting ions Ce³⁺in the membrane are released to the surface of the aluminum alloy to form Ce（OH）3,forming a dense film and preventing the infiltration of chloride ions,which effectively inhibits the stress corrosion cracking process.