Aluminium & Zinc Sprayed Coatings
Impreglon UK is a leading applicator of thermally sprayed Aluminium and Zinc coatings. Applied by arc spray, these coatings are usually used for corrosion resistance.
Zinc (known as Thermally Sprayed Zinc or TSZ) and Aluminium (known as Thermally Sprayed Aluminium or TSA) are used for galvanic corrosion protection.
Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially to another when both metals are in electrical contact and in the presence of an electrolyte. It is a property exhibited by dissimilar metals where they have different electropotentials. When two or more come into contact in an electrolyte, one metal acts as anode and the other as cathode. The electropotential difference between the dissimilar metals is the driving force for an accelerated attack on the anode member of the galvanic couple. The anode metal dissolves into the electrolyte and deposit collects on the cathodic metal.
This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited. The presence of an electrolyte and an electrical conducting path between the metals is essential for galvanic corrosion to occur. So in an offshore application for example, the seawater would act as the electrolyte. And the Aluminiun or Zinc coated part would be the anode. Either metal can be used though Zinc has a greater electropotential difference with steel.
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