Design And Test Of Self-healing Coatings For Ship Structure

The different parts of the ship working on the sea suffer from different environment and can be corroded and damaged due to long-term use,which will cause significant economic losses to society.Self-healing coating technology can repair small cracks due to external effects to extend the life of the ship’s structure.Improving the coating properties can reduce the cost of the coating.The design and the test of the self-healing coatings of the ship structure was studied in this thesis,and the corrosion resistance of the self-repairing coatings was explored.Firstly,the microcapsules as a self-healing coatings key technology was studied.The preparation program for microcapsules was optimized by experiments,and the microcapsules with the urea-formaldehyde resin as shell material were prepared by two-step synthesis method.The microcapsule surface morphology was observed by scanning electron microscope(SEM),the thermal properties of microcapsules were analyzed by the thermal gravimetric analysis(TG)and differential scanning calorimetry(DSC),and the chemical structure of the microcapsules were characterized by Fourier transform infrared spectroscopy(FTIR).The surface morphologies of the microcapsules prepared by the one-step and the two-step were characterized,and the results showed that the distribution of the microcapsules prepared by the two-step method was more dense and rough than that prepared by the one-step method,and the microcapsules by the two-step method had better adhesiveness with the matrix material.The thermal stability of microcapsules prepared by the two-step method were analyzed by the thermal gravimetric analysis(TG)and the differential scanning calorimetry(DSC),and the results showed that the microcapsules with the urea-formaldehyde resin as shell material displayed good thermal stability and start to decompose at about 225℃.The chemical structure of the microcapsules were characterized by Fourier transform infrared spectroscopy(FTIR),and the results indicated that the urea-formaldehyde resin wall material was formed.Then,the preparation process of the aqueous epoxy anti-corrosion coatings and the influence factor of its property were analyzed.The experiment validated that film-forming substance of the coating was the epoxy resin and the curing agent was the epoxy curing agent.The type and amount of additives were also defermined by experiment.The dosage of DW-432 dispersant,DD-130 cancellation foam and JF were 4 percent,0.3 percent,0.6 percent respectively,and the environmental protection zinc phosphate was filler.In addition,the amount of the 501 epoxy reactive diluent accounted for 20 percentage of the amount of epoxy resin.If diluent was too little,the dilution effect was not obvious,on the contrary,the viscosity of the epoxy could be reduced.When the ration between resin and hardener was 1.1,the overall performance of film was the best.Finally,some preliminary exploration for the design and detection of the self-healing coating was carried out,the microcapsules were incorporated into the anti-corrosion coatings to prepared the self-healing coatings.The effects of the amount of microcapsules on the self-healing coatings corrosion resistance were investigated,and the self-healing properties of self-healing coatings was also analyzed.