埋地管线防腐阳极供应商-镁合金牺牲阳极权威厂家

 

根据铝和锌的含量不同，性能不同，其中性能较好和获得广泛应用的主要是Mg-6Al-3Zn-Mn合金，其表面溶解均匀，电流效率大于50%.铝是阳极中的主要合金元素，可与镁形成Mg17 A112强化相，提高合金的强度。但向工业镁中单独添加铝时，可形成大量的Mg Al, Mg2A13, Mg4 A13等金属间化合物，这些金属间化合物的存在，都会增大镁的自腐蚀速度、加速固溶体的破坏。锌可降低镁的腐蚀率，减小镁的负差异效应，提高阳极电流效率。微量的锰可抵消杂质铁、镍的不良影响。当锰的添加量为0.3%时，可使铁的允许含量达到0.02%，但同时也会降低电流效率。因此，杂质铁的含量以及相应的锰含量应尽可能低。铝、锌、锰的同时存在可进一步降低对工业镁中的杂质元素含量的要求。为了获得良好的电化学性能，Mg-AI-Zn-Mn系合金的杂质含量应严格控制。在相近的合金成分条件下，杂质少的合金的电流效率明显高于含杂质多的合金。

  阴极保护是基于电化学腐蚀原理的一种防腐蚀手段。美国腐蚀工程师协会对阴极保护的定义是：通过施加外加的电动势把电极的腐蚀电位移向氧化性较低的电位而使腐蚀速率降低。牺牲阳极阴极保护就是在金属构筑物上连接或焊接电位较负的金属,如铝、锌或镁。阳极材料不断消耗,释放出的电流供给被保护金属构筑物而阴极极化，从而实现保护。外加电流阴极保护是通过外加直流电源向被保护金属通以阴极电流，使之阴极极化。该方式主要用于保护大型或处于高土壤电阻率土壤中的金属结构。 [1]

  保护电位是指阴极保护时使金属腐蚀停止（或可忽略）时所需的电位。实践中，钢铁的保护电位常取-0.85V（CSE），也就是说，当金属处于比-0.85V（CSE）更负的电位时，该金属就受到了保护，腐蚀可以忽略。

 

According to the different contents of aluminum and zinc, the properties are different. among them, mg - 6al - 3zn - Mn alloy, which has better properties and is widely used, has a unib surface dissolution and a current efficiency of more than 50 %. aluminum is the main alloy element in the anode and can b a mg17a112 strengthening phase with magnesium to improve the strength of the alloy.  However, when aluminum is added to industrial magnesium alone, a large amount of interbllic compounds such as mg al, mg2a13, mg4a13 can be bed. the existence of these interbllic compounds will increase the self-corrosion rate of magnesium and accelerate the destruction of solid solution.  Zinc can reduce the corrosion rate of magnesium, reduce the negative differential effect of magnesium, and improve the efficiency of anode current.  Trace amount of manganese can offset the adverse effects of impurities such as iron and nickel.  When the amount of manganese added is 0.3 %, the allowable content of iron can reach 0.02 %, but at the same time the current efficiency can also be reduced.  Therefore, the content of impurity iron and corresponding manganese should be as low as possible.  The simultaneous presence of aluminum, zinc and manganese can further reduce the requirements for impurity elements in industrial magnesium.  In order to obtain good electrochemical perbance, the impurity content of mg - ai - Zn - Mn alloy should be strictly controlled.  Under similar alloy comb conditions, the current efficiency of alloys with less impurities is obviously higher than that of alloys with more impurities.
 Cathodic protection is an anti-corrosion b based on electrochemical corrosion principle.  The American society of corrosion engineers defines cathodic protection as the reduction of corrosion rate by applying an applied electromotive force to shift the corrosion electricity of the electrode to a potential with lower oxidation.  Sacrificial anode cathodic protection is to connect or weld bls with negative potential on bl structures, such as aluminum, zinc or magnesium.  The anode material is continuously consumed, and the released current is supplied to the protected bl structure while the cathode is polarized, thus realizing protection.  Impressed current cathodic protection is to apply cathodic current to the protected bl through an impressed DC power supply to polarize it.  This b is mainly used to protect bl structures in large or high soil resistivity soils.  [1]
 The protection potential refers to the potential required to stop ( or ignore ) bl corrosion during cathodic protection.  In practice, the protective potential of steel is usually - 0.85 v ( CSE ), that is, when the bl is at a more negative potential than - 0.85 v ( CSE ), the bl is protected and corrosion can be neglected.

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