Q1: Corrosion of metals can not be prevented by its

ANS:A - tempering

Corrosion of metals can be prevented or mitigated through various methods, including tempering, chromizing, aluminizing, and alloying. Each of these methods offers different mechanisms for corrosion protection:

1. Tempering: Tempering is a heat treatment process that improves the toughness and ductility of metals, particularly steels, by reducing their hardness. While tempering does not directly prevent corrosion, it can enhance the overall performance of metal components by reducing susceptibility to stress corrosion cracking and hydrogen embrittlement.
2. Chromizing: Chromizing involves the application of chromium-rich coatings to the surface of metals, typically through techniques such as electroplating or chemical vapor deposition. Chromium coatings provide excellent corrosion resistance by forming a protective oxide layer (chromium oxide) that prevents further oxidation of the underlying metal.
3. Aluminizing: Aluminizing is a surface treatment process that involves the diffusion of aluminum into the surface layer of a metal substrate, typically through pack cementation or chemical vapor deposition. Aluminum forms a protective oxide layer (aluminum oxide) on the surface, which acts as a barrier against corrosion and oxidation.
4. Alloying: Alloying involves the addition of alloying elements to the base metal to improve its properties, including corrosion resistance. For example, stainless steels are alloys of iron, chromium, nickel, and other elements, known for their excellent corrosion resistance due to the formation of a passive chromium oxide layer on the surface.