zielsicher Englisch, Metalltechnik, Schulbuch

Corrosion and corrosion protection methods. Read the following text. Most metals and alloys develop changes on their unprotected surfaces, which leads to continuous destruction called corrosion. Corrosion is the reaction of a metallic material to its surroundings, leading to a damaging change to the metal’s surface. Corrosion protection has a great economic importance, because almost any metallic component is destroyed without some sort of corrosion protection. Surface treatment is not only for protection, but also for the embellishment of a product. Therefore, the dura­ bility, as well as the sales value, is increased. Corrosion has many different manifestations. There is not only a chemical but also, an electrochemical type of corrosion. Protection against corrosion can be active, passive or cathodic. Fill in the missing words from the box to complete the sentences. electrochemical manifestations active cathodic passive chemical 1. Chemical  corrosion is caused by gases, acids, alkaline solutions, salts, or water. 2. Electrochemical  corrosion is the decomposition of different metal materials by voltaic processes. 3. Manifestations  of corrosion show as surface corrosion, pitting corrosion, crevice corrosion, contact corrosion, stress corrosion, inter-crystalline corrosion, corrosion due to oscillation. 4. Active  corrosion protection is when characteristics of the work piece or of its surroundings are changed (such as coating with alloys, or conditioning of the air around the work piece). 5. Passive  corrosion is where the work piece and its surroundings are separated by painting. 6. Cathodic  corrosion protection can be effected by a protection electrode (sacrificial anode) or by a voltage source. Mosaic What do you think happened to this old lock? What kind of corrosion could that be? Think about a cottage at the sea. Salt, windy weather … chemical corrosion due to salt and water 07 A2–B1 Word bank destruction Zerstörung continuous fortlaufend embellishment Verschönerung acid Säure alkaline solution Lauge decomposition Zersetzung voltaic processes galvanische Prozesse manifestations Erscheinungen sacrificial anode Opferanode cathodic kathodisch pitting corrosion Lochfraß crevice corrosion Spaltkorrosion stress corrosion Spannungskorrosion corrosion due to oscillation Schwingungs­ korrosion 08 A2–B1 21 3 Various working materials Nur zu Prüfzwecken – Eigentum des Verlags öbv