| Due to it is rich in mineral resources,sea water resources,marine biological resources and other natural resources,ocean has important strategic value.However,the exploration and development of marine is limited seriously owe to the serious marine corrosion conditions,and the marine equipment suffers the serious corrosion problems for a long time.Therefore,it is of important significance for the construction and development of national economy and military equipment to make use of the marine corrosion control technology reasonably,design and prepare the marine anti-corrosion coating with better protective properties to improve the service safety and life of the marine equipment.With the excellent mechanical properties and outstanding corrosion resistance,Titanium(Ti)has been widely used in aerospace,petrochemical industries,metallurgical manufacturing and other fields.It can make a good corrosion resistance coating by adding some Nano-Ti as filler to the coatings.However,the dispersion,stability,and addition problems of Nano-Ti in coatings have not been solved effectively,and there is little work about the protective mechanism.Therefore,Nano-Ti was prepared by high energy ball milling system.The effect of different ball-to-powder ratio,ball diameter ratio,grinding agents and milling time on microstructure and properties of Nano-Ti polymer were investigated by sedimentation tests,laser particles analysis,scanning electron microscopy(SEM),transmission electron microscopy(TEM),fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS).The grafting reaction and phase evolution of Nano-Ti polymer was studied from micro-nano view,and the formulation mechanism was revealed.Nano-Ti polymer coating was designed,optimized and prepared by orthogonal design experiment.The effect of different Nano-Ti polymer addition on microstructure and properties of coatings were characterized by general properties tests,SEM,FT-IR,ultraviolet aging experiment,artificial seawater immersion test and neutral spray experiment.The inhibitory kinetics of serious corrosion factors(chloride concentration and high humidity)for different coatings,the relationship between environment factors and electrochemical parameters(corrosion potential and current)were analyzed by electrochemical impedance spectroscopy(EIS).The corrosion protective mechanism was explained.According to the above studies,the conclusions are as follows:(1)Preparation process of Nano-Ti polymer was designed and optimized by high energy ball milling.Nano-Ti polymer exhibits excellent dispersion stability as the ball weight is 2600g,the diameter ratio is?20mm:?15mm:?5mm=16:7:3,the grinding agent is epoxy resin with acetone,milling time is 4h.(2)The derivation mechanism of Nano-Ti polymer is investigated by studying different milling time.The dispersion stability of Nano-Ti polymer improves,the Ti particles size decreases,the distortion of Ti particles increases as extension of milling time.The phase of Ti tends to amorphous.It means that there is a grafting reaction between Ti and epoxy resin as the number of epoxy group decrease or disappear and the graft quantity of Ti increases.Finally,the Nano-Ti polymer is formed.(3)Preparation process of Nano-Ti polymer was designed and optimized by orthogonal design.Nano-Ti polymer coating is uniform and compact.The general properties tests show that it is with excellent mechanical properties,and the effect of Nano-Ti polymer addition on properties of coating is very important.The thermal stability increases,and the glass-transition temperature also improves as the addition of Nano-Ti polymer increases.The coating shows the highest temperature as the addition of Nano-Ti polymer is 9%,206.1?.(4)The Nano-Ti polymer coating after laboratory environment simulation experiment of immersion test in 3.5%NaCl solution for 10000h,neutral spray test for3000h,and ultraviolet aging test for 200 days show that it displays outstanding permeation resistance and corrosion resistance.The protective property is enhanced with the increases of Nano-Ti polymer addition.It shows the best anti-corrosion properties as the addition of Nano-Ti polymer is 9%.(5)The results of EIS show that Nano-Ti polymer coatings exhibits outstanding anti-corrosion properties,it is as excellent as before after immersion for 458days.It is a large-resistance and low-capacitance anti-corrosion-insulation coating,and it can restrain the corrosion medium to reach to the matrix during the immersion.The coating resistance decreases at first then stable at a certain value as the immersion time increase.The resistance increases up to a peak as the addition of Nano-Ti polymer is9%,9.3×10~8?·cm~2,it shows excellent protective effects.It is because that a good compatibility of different component in the coating,and a good uniform and compact coating can be formed due to the special“stubble”structure of Nano-Ti polymer.It can stop the corrosion medium from entering,prolong the anti-corrosion direction,reduce the corrosion rate,enhance the shielding properties for corrosion medium,improve the protective property of Nano-Ti polymer coating effectively.(6)Combined with the above results,the coatings were applied on the surface of the liquid nitrogen/hydrogen pipelines and towers of a launch site to control the corrosion states.They all exhibits excellent anti-corrosion properties after 25 months.From the above studies,the results show that Nano-Ti polymer exhibits excellent dispersion stability,Nano-Ti polymer coating with“stubble”structure displays outstanding long-term,anti-corrosion,weathering resistance.It can meet the corrosion protection standards of marine equipment in the marine environment.Besides,it provides the theoretical basis and technical support of corrosion and protection for marine equipment. |
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