Preparation And Performance Study Of Hot Dip Aluminum-Based Alloy/Silane Composite Coating On The Surface Of P110S Steel

With the continuous development of oil and gas field exploitation in depth,the service environment of tubing deteriorates sharply,bring serious tubing corrosion damage and fracture failure problems.The high cost and insufficient protection performance of present oil pipeline corrosion prevention measures affect the safe operation of ultra-deep oil fields.In this study,it tried to prepare aluminum base alloy coating on P110S steel surface by low-cost hot dip plating method and the principle of sacrificial anode.Aluminum alloy anode coating realized the physical isolation of corrosive media with sacrificial anode protection characteristics.In this work,the influence of coating preparation process parameters on its protection performance was studied,so as to achieve the optimization of the preparation process,the introduction of green and excellent corrosion resistance silane surface treatment technology to construct metal/organic composite coating,effectively improve the service life of hot dip aluminum-based alloy coating.In this paper,the hot dip aluminum-based alloy coating is prepared first.The surface pretreatment of P110S steel was realized based on the design of potassium fluoride plating aid system.The influence of different components of plating aid on the coating surface quality is studied,and the most effective new components of plating aid are determined.The effect of hot dip plating parameters（hot dip plating temperature,hot dip plating time）on the structure and properties of hot dip aluminum base alloy coating was studied.Hot dip aluminum-based alloy coating is mainly divided into two layers,the outer layer（aluminum-rich layer）is mainly composed of Fe Al₃ phase,and the inner layer（alloy layer）is mainly composed of"wavy"Fe₂Al₅ phase.The effect of hot dip plating temperature on the growth kinetics of the alloy layer was studied,the alloy layer was mainly controlled by diffusion mechanism.The optimal parameters of hot dip aluminum-based/silane composite coating were determined as follows:hot dip plating temperature of 740℃ and hot dip plating time of 2 min,and the coating quality was better and the alloy layer was thinner.Secondly,in order to effectively improve the service life of aluminum base alloy anode coating,BTSE-KH560 double coating technology was used to construct hot dip aluminum base alloy/silane composite coating.The silane coating performance was optimized based on three main process parameters:hydrolysis time of silane solution,silane solution concentration and curing temperature.The experimental results of simulated oilfield environment in the laboratory show that obvious corrosion of P110S steel occurs after 5 days of immersion test,and red rust occurs after 140 days of hot dipping aluminum-based alloy coating.The composite coating of hot dipping aluminum-based alloy/silane prepared with optimal parameters can safely protect P110S steel for more than 220 days.The silane composite coating plays an outstanding role in shielding erosive ions from oilfield production fluid,and achieves the expected design index.The formation mechanism and corrosion resistance mechanism of hot dip aluminum-based/silane composite coating were studied.