Preparation And Corrosion Behavior Of Ni-W/TiN Coated X52 Pipeline Steels

It is well known that the oil pipeline is one of the main pipeline systems for oil transportation.Due to the wide range of oil pipeline laying and different climate conditions,the oil pipelines are often affected by the soil corrosion,microbial action,crude oil corrosion,quicksand erosion and other influence factors,resulting in the oil pipeline leakage,corrosion cracking,perforation and other accidents.Therefore,the surface modification of the oil pipeline is required to carry out for improving the surface hardness,wear resistance,corrosion resistance and other properties of the pipeline,and then the service life of the pipeline is increased.In addition,the safe operation reliability of pipelines is also enhanced.Ni-W coating has some excellent characteristics in high temperature resistance,oxidation resistance,wear resistance and corrosion resistance,and it is very suitable for the surface modification or anti-corrosion treatment of plunger,cylinder sleeve,multi-phase oil transmission pipeline,and son on.Therefore,the Ni-W/Ti N coatings were prepared on the surfaced of X52 pipeline steel by using ultrasonic electrodeposition method,and the corrosion mechanism of Ni-W/Ti N coated X52 pipeline steel was discussed in detail,and the surface appearance,phase composition and corrosion resistance of the samples were also examined.And then the Ni-W/Ti N coated X52 pipeline steels with excellent comprehensive performance were prepared.A new corrosion protection method for protecting the oil pipeline was also discussed.In addition,the influences of corrosion medium on corrosion potential,corrosion morphology and corrosion mass losses of the Ni-W/Ti N coated X52 pipeline steels were investigated by exploring the corrosion behaviors of the Ni-W/Ti N coated X52 pipeline steel in soil medium,sodium chloride solution,sodium sulfate solution and sodium chloride-sodium sulfate mixed solution.This technique will demonstrate a new corrosion protection method for oil transmission pipeline.The research results are listed as follows:（1）The preparation method,process and plating composition for fabricating Ni-W/Ti N coating X52 pipeline steel were introduced.And the BP neural network model and orthogonal experimental method were utilized to optimize the component ratio,and the optimal ratio was listed as follows:Ni SO₄240 g/L,Na₂WO₄30 g/L,Ni Cl₂30 g/L and Ti N 10 g/L.（2）A CS350 type electrochemical workstation was utilized to determine the electrode cyclic voltammetry curve of the ultrasonic electrodeposited Ni-W/Ti N coated X52 pipeline steel,and the deposition mechanism and kinetics of crystallization process of the Ni-W/Ti N coated X52 pipeline steel were researched.In the Ni,Ni-W and Ni-W/Ti N coatings,the higher the potential of metal nucleation,the faster the nucleation rate of the coating was.In addition,the lower the potential of metal nucleation,and the slower the growth rate of the coating was.（3）The COMSOL Multiphysics software was utilized to simulate the soil stress corrosion behaviors of Ni-W/Ti N coated X52 pipeline steel under different prefabricated defect radii.With the decrease of the precast defect radius,the stress value inside the steel sample of X52 pipeline was larger.The results indicated that the soil corrosion of X52pipeline steel was more serious than that of Ni-W/Ti N coated X52 pipeline steel,resulting in the corrosion cracking or perforation of X52 pipeline steel.（4）In order to study the effect of soil corrosion medium in the soil environment on the corrosion behavior of X52 pipeline steel and Ni-W/Ti N coated X52 pipeline steel,the soil simulation liquid of Daqing oilfield was dispensed,and the dynamic potential scanning technology and EIS mapping detection technology were utilized to discuss the influence of different soil temperature,soil p H and soil oxygen content on X52 pipeline steel and Ni-W/Ti N coated X52 pipeline steel.When the temperature,p H value and oxygen content of soil simulation solution were the same,the results indicated that the corrosion resistance of Ni-W/Ti N coated X52 pipeline steel was much greater than that of X52 pipeline steel.（5）The influences of corrosion medium on the corrosion potential,corrosion morphology and corrosion products of Ni-W/Ti N coated X52 pipeline steel were investigated by investigating the corrosion behavior of X52 pipeline steel and Ni-W/Ti N coated X52pipeline steel in the soil medium,sodium chloride solution,sodium sulfate solution and sodium chloride-sodium sulfate mixture solution.In the corrosion process of Na Cl-Na₂SO₄mixed corrosion solution,the corrosion current density of Ni-W/Ti N coated X52 pipeline steel increased slowly,and the average corrosion current density was 75.6μA/cm².Because Ni-W/Ti N coatings processed the dense and smooth structures,which hindered the corrosion of Na Cl-Na₂SO₄solution on X52 pipeline steel.And then the corrosion current density of Ni-W/Ti N coated X52 pipeline steel was small.Therefore,it can be seen that Ni-W/Ti N coating plays a protective effect on X52 pipeline steels.