Experimental Study On Damage Of Viscoelastic Anticorrosive Coatings Under Sand Flow At High Velocity

With the development of inland waterway transportation,steel components have been widely used in inland port construction.At present,the steel components anticorrosion design of inland ports in China mainly refers to the steel structure anticorrosion code of seaport engineering,and uses epoxy asphalt anticorrosion coating for protection.Through field investigation,it is found that the anticorrosive coating of steel sheathed rock-socketed piles and berthing members for lower part of inland river wharf is continuously eroded by the sand flow.As a result,its anticorrosive coating falls off on a large scale,leaving the steel components exposed to rust.The corrosion is very serious,which directly affects the normal use of the hydraulic steel components.It is an important problem to be solved urgently in the maintenance of port engineering that the anticorrosive coating is rapidly eroded by the sand flow at high velocity.In this paper,the erosion damage characteristics of viscoelastic anticorrosive coatings for steel components under the sand flow at high velocity were studied by using accelerated erosion test and physical model test in laboratory,and the abrasion prediction model of viscoelastic anticorrosive coatings was proposed.The main research work and achievements are as follows:(1)Comparative analysis of basic mechanical properties of coating materials The working characteristics of the inland river wharf in the upper reaches of the Yangtze river and the anticorrosion requirements of the steel structure were considered,the basic mechanical properties of epoxy asphalt coatings and three kinds of polyurethane coatings with good mechanical properties were tested in this paper.Comparison of the measured results shows that:Epoxy asphalt coating has higher hardness than polyurethane coating,but its adhesion and impact resistance are weaker than polyurethane coating.The adhesive properties of polyurethane coatings with three ratios are all greater than the elastic properties.When the ratio is 1:3,the adhesive properties are the largest.(2)Accelerated erosion test study on erosion damage characteristics of viscoelastic anticorrosive coatings.The accelerated erosion tests of epoxy asphalt coatings and three kinds of polyurethane coatings on steel components under different erosion conditions were carried out by using a self-made accelerated erosion device,the erosion damage law of coating surface under different erosion conditions was obtained.The results showed that the erosion resistance of polyurethane coating was better than that of epoxy asphalt coating,in which the abrasion of polyurethane 1:3 coating was the least and the erosion resistance was the best.(3)Physical model test of erosion damage characteristics of viscoelastic anticorrosive coatings.Through the laboratory flume model test of erosion damage of epoxy asphalt coating and three kinds of polyurethane coating on steel components under different erosion conditions,the abrasion amount of each anticorrosive coating was obtained.The results show that the results of laboratory physical model test and accelerated erosion test have a similar rule under the same erosion condition.In addition,based on the similarity theory,the correlation between accelerated erosion test and laboratory flume model test is established.(4)The prediction model of abrasion of anticorrosive coating was established.Based on the constitutive model of viscoelastic coating and the theory of contact mechanics,the mechanical model of the viscoelastic anticorrosive coating on steel components washed away by sand flow was established,and the prediction model of the erosion amount of the viscoelastic coating was derived.Through the comparison and analysis with the test results,the undetermined parameters in the prediction model are determined and the correctness of the calculation results of the prediction model is verified.At the same time,erosion effect is predicted based on the stress field of the coating with sand flow contact.The maximum contact force and the maximum normal stress of the polyurethane coating with a ratio of 1:3 are lower than the rest,indicating that the degree of abrasion is correspondingly minimum,which is the optimal viscoelastic anticorrosive coating.