Abstract
In order to accelerate the exploration of ocean resource, the human build lots of immovable and movable structures in the sea.The iron structures exposing in the ocean environment are severely corroded in splash zone.In this zone, the most primary failure forms is erosion- corrosion.So, studying coatings’ resistance to erosion-corrosion is meaningful to creating high performance coatings in splash zone.
This paper invent a rotate-jet test machine on slurry erosion-corrosion to simulates the environment of splash zone.This machine include five systems such as rotate controlling system,sample fixing system,liquid(liquid-soild) jet system,temperature controlling system,electrochemical system.The parameters which include impact velocity ,impact frequency,impact distance,temperature,sample numbers are variable.It can compare the resistance to erosion between different materials and analyze corrosion factor during erosion-corrosion by electrochemical detecting.After testing, the slurry flow and concentration is steady-going and the data reappearance of parallel samples is good.
Metal coatings on iron which include aluminium, titanium, aluminium-titanium,zinc- aluminium, aluminium bronze are made by arc sprying. Then put them to the rotate-jet test machine for studying resistance to erosion-corrosion between different coatings. The protection effect of titanium-aluminium、zinc-aluminium coating are better;aluminium coating is worse than them;titanium、aluminium bronze coating are worst.The titanium coating which has high hardness and brittleness crack during erosion;the aluminium coating which has high plasticity and low hardness blister during erosion;the titanium-aluminium coating which has good toughness has honeycomb-like and sponge-like structure during erosion.
The erosion-corrosion mechanism is influenced by impact velocity and impact frequency.The failure of coating is controlled by corrosion at low impact velocity and impact frequency. It is controlled by erosion at medium impact velocity and impact frequency and controlled by cavitition at high impact velocity and impact frequency.
This paper monitors the open circuit potential and corrosion current density of coatings by electrochemical method during erosion-corrosion.Some conclusions are obtained about the test parameter and metal coating’s electrochemical property. Shearing force producing by higher impact frequency can break passive film, reduce the potential of coatings. Higher temperature can increase the activity of ion and charged particles; accelerate diffusion; break passive film. So the potential of passive coating decrease, but the sacrificial anode coating’s potential is little affected. At low impact frequency, higher impact velocity can also increase the coating’s potential.Erosion can increase corrosion current.The coatings controlled by corrosion have stable corrosion current, but they are sensitive to the change of erosion .The corrosion current of coatings which have good resisitence to erosion increase a little with the time flying and they are not sensitive to the change of erosion.
Keyword: Erosion-corrosion，Test Machine，Splash Zone， Arc Spraying，Metal Coatings，Cavitation
本站文章未经允许不得转载；如欲转载请注明出处，北京桑尧科技开发有限公司网址：http://en.sunspraying.com/
|
