NACE CP1 – Questions and Answers Already Passed

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NACE CP1 – Questions and Answers Already Passed corrosion ✔✔The deterioration of a substance, usually a metal from a reaction with its environment Passivation ✔✔A layer of oxides formed on the surface of a metal that provides corrosion protection. the elements of a corrosion cell ✔✔Anode, cathode, metallic pathway, electrolyte what happens at the anode ✔✔The metal dissolves into the electrolyte the function of the metallic pathway ✔✔Allows the flow of electrons to connect the corrosion cell galvanic series ✔✔A listing in order of reactivity ( more or less noble) in seawater 25c The general rules of galvanic corrosion ✔✔The less noble (more reactive) metal when connected to a more noble (or less reactive metal) will corrode preferentially. the five most important factors that affect the rate of corrosion. ✔✔Humidity, oxygen, chemical salts, pollutants, temperature General corrosion ✔✔Results in a relatively uniform loss of material over the entire surface. Results in a general thinning of the affected surface. Realively easy to inspect. Does not cause catastrophic failures. Localized corrosion ✔✔Typically pitting and crevice corrosion. It is typically of the most concern as damage is concentrated and loss of integrity or structure failure can result. Common tool/ methods used for corrosion control. ✔✔Design, inhibitors, material selection, cathodic protection, protective coatings, splash zone systems, alteration of the environment Anode ✔✔The electrode of an electrochemical cell at which oxidation occurs. Electrons flow away from the anode in the external circuit. Corrosion usually occurs and metal ions enter the solution at the anode. Cathode ✔✔The electrode of an electrochemical cell at which reduction is the principal reaction. electrons flow towards the cathode in the external circuit. Cathodic protection ✔✔A technique to reduce the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. Corrosion cell ✔✔In order for corrosion to occur, certain conditions and elements are essential. This is the combination of an anode, cathode, return path, and electrolyte. Corrosion inhibitor ✔✔A chemical substance or combination of substances that, when present in the environment, prevents or reduces corrosion Crevice corrosion ✔✔Localized corrosion of a metal surface at or immediately adjacent to an area that is shielded from full exposure to the environment because off close proximity of the metal to the surface of another material Electrolyte ✔✔A chemical substance containing ions that migrate in an electric field Mill scale ✔✔The oxide layer formed during hot fabrication or heat treatment of metals Pitting ✔✔Localized corrosion of a metal surface that is confined to a small area and takes the form of cavities called pits. Return path (metallic pathway) ✔✔This connects the anode and cathodes allowing passage of electrons generated at the anode to the cathode.

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