节点文献

电弧喷涂金属涂层耐海水冲蚀性能研究

Study on the Resistance of Arc Spray Metal Coatings to Erosion in Splash Zone

【作者】 魏金鑫

【导师】 王勇;

【作者基本信息】 中国石油大学 , 材料加工工程, 2009, 硕士

【摘要】 为了加速海洋资源的开发,人类在海洋中建造了无数固定与活动的海上构筑物。暴露于海洋环境中的钢构造物,腐蚀最严重的区域是浪花飞溅区,其主要的失效形式之一是冲刷腐蚀。为了得到性能优异的防腐涂层,研究防腐涂层的冲刷腐蚀性能对新型涂层制备有重大意义。本文模拟浪花飞溅区的环境特点,设计并制造了一台旋转喷射式冲蚀试验机。该试验机可分为旋转控制系统、试样装夹和固定支撑系统、液(液固)体循环喷射系统、温度控制系统和电化学测试系统五大部分。试验机可实现冲击速度、冲击频率、溶液温度、冲击角度、冲击距离、悬挂试样数量可控,可比较不同材料的抗冲蚀性能,且通过电化学腐蚀测试监测材料冲蚀失效过程中的腐蚀分量,从而分析各因素的影响。试验机浆料流量和浓度稳定,平行试样的数据重现性良好。利用电弧喷涂设备,在碳钢基体表面制备了铝、钛、铝钛、铝锌和铝青铜五种涂层试样,在上述自制的冲蚀试验机上进行了冲蚀试验,研究了不同涂层的耐冲蚀性能。结果发现,铝钛、铝锌涂层保护效果较好,铝涂层保护效果居中,钛和铝青铜涂层的保护效果差。对于硬脆的钛涂层,涂层冲蚀后即产生裂纹;对于硬度低,塑性好的铝涂层,涂层冲蚀后产生鼓泡和花蕾状破坏;对于塑韧性较好的铝钛涂层,冲蚀后产生蜂窝和海绵状的破坏结构。冲击速度和冲击频率对涂层的冲蚀失效机制有重要影响。研究发现,当低流速、低冲击频率时,即冲击速度4m/s,冲击频率为1/6Hz,涂层主要以腐蚀为主;当增加冲击频率时,即冲击频率为1/3Hz,涂层以腐蚀和流体冲刷为主;进一步增加冲击流速和冲击频率,即冲击速度为8m/s,冲击频率为1Hz,涂层产生了空蚀,主要以力学作用为主,腐蚀为辅。在进行冲蚀试验的过程中,采用电化学方法监测了涂层自腐蚀电位和自腐蚀电流密度的变化。试验发现,冲击频率升高,其产生的剪切力能破坏钝化膜,使电位降低;对于牺牲阳极为主的涂层,能加速腐蚀,电位稍微正移。温度升高,可以增加离子和带电体的活性,促进扩散,使得钝化涂层电位降低,但对牺牲阳极型涂层影响很小。在低冲击频率下,流体冲击速度升高使涂层钝化容易,电位升高。经线性极化分析得知,冲蚀能增大腐蚀电流,对腐蚀有加速作用。对于腐蚀占比例较大的涂层,只要冲蚀机制不改变,涂层腐蚀电流基本不变,但其对冲蚀变化敏感。随冲蚀时间延长,铝钛涂层腐蚀电流略微升高,但增加冲击频率时,其腐蚀电流变化很小,对冲蚀变化不敏感。

【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.

节点文献中: 

本文链接的文献网络图示:

本文的引文网络