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Surface Hardening Treatments

ProfessorAli Hussein ATAIWI

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*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.

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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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-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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