| This paper firstly gave a brief overview on the past and the future of the abrasion resistant coatings, and then the major work focused on the preparation of the epoxy resin / polyurethane (EP/PU) IPN using the graft co-polymerization method and on the investigation on its related abrasion resistant coatings used for components serving in hydraulic engines.The characteristics of abrasion resistant coatings used for components serving in hydraulic engines were that them included three layers of coatings: a zinc-riched epoxy primer, an epoxy micaceous iron mica intermediate coating and a top layer of abrasion resistant coating, and the top layer with the modified epoxy resin binder and the rigid ceramic aggregate had good erosion wear resistance. For the primer, the corrosion resistant mechanism and the effects of the fraction of zinc powder in weight, the amounts of ferrophosphorous powder and the silane coupling agent on the primer were studied. It was found that the zinc-riched primer had excellent corrosion resistant property when the fraction of zinc powder was of 80wt% in weight, the ratio between ferrophosphorous and the epoxy mucus was 0.25. and the metal substrate was treated by KH-550 type silane coupling agent. For the intermediate coating, optimal composition of the coating was obtained by the orthogonal method. In addition, the corrosion resistant mechanism, the curing mechanism, the curing kinetics, and the thermal cracking process of this coating were investigated in depth. The results showed that the scale-like structure of micaceous iron mica prevented the substrate from corrosion effectively. It was also found that the curing reaction was the reaction between the epoxy and amine groups when the EP was cured by the polyamide (LMPA) with low molecular weight. The surface activation for the reaction was 75.2 kJ/mol. The toughness and the impact resistance improved, but the corrosion resistance reduced with the increase of the content of LMPA with in a specific range. On the other hand, the curing degree depended on the temperature. Theresults indicated that the higher the temperature, the higher curing degree would be, and the coating completely cured at 120 . For the top layer (abrasion resistant coating), the modification mechanism of modified epoxy, the curing mechanism, the wear mechanism, and the effects of the aggregate content, the aggregate size, and the coating thickness on the erosive wear resistant property of the abrasion resistant coating were investigated. The results showed that the modified epoxy resin with excellent properties was prepared when the ration of PU/EP was 0.3, and the drying time in the air was about 3~5 days at room temperature with the ratio of LMPA/EP 50wt%. It was also found that the abrasive resistant property of the coating was about 2 times of the As steel under the proper conditions.The abrasion and corrosion resistance of the fabricated coatings were studied in the present work. The erosive wear resistance of the coatings was better than those of the others reported in the literature. The results indicated that the good erosive wear resistance of the fabricated coatings was resulted from the absorption between the primer and the substrate, the diffusion between the three layers, the strong covalent bond coherence of the SA, and the mechanical interlocking. The anodic polarization curves of the top layer, the top layer + the intermediate layer, and the top layer + the intermediate layer + the primer layer showed that these coatings protected the substrate effectively with the increase of the number of the layers. The coatings have been used to improve the erosion wear resistance of the water-wheel machines successfully. |
PDF Full Text Request