Professor Ali Hussein ATAIWI 1

2 *There are many situations where the need for good wear or fatigue resistance for surface to a component while the requirement for a tough material with good resistance to impact failure would indicate the need for a soft,ductile core. * These requirements are accomplished by surface hardening treatments.

3 Various methods are used for surface hardening and are grouped into two categories: 1-changing the composition of the surface layers: carburizing, nitriding & cyaniding 2-selective heating of the surface layer,i.e. surface heat treatment :.induction hardening,flame hardening

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10 -carburizing compounds They are reusable and contain 10 to 20 alkali or alkaline earth metal carbonate bound to hard wood charcoal or to coke by oil, tar, or molasses. Barium carbonate is the principle energizer, usually comprising about 50 to 70% of the total carbonate content. The remainder : calicum carbonate + sodium carbonate.

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