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METALLURGICAL PROESSES

GALVANISATION:

PROCESS OF GIVING A THIN COATING OF ZINC ON IRON ARTICLES.IT PROTECTS IRON ARTICLES FROM RUSTING AS WELL AS CORROSION.ZINC BEING MORE ELECTROPOSITIVE THAN IRON, EVEN EXPOSED SURFACES OF IRON DO NOT RUST, AS THE MOISTURE PREFERS TO ATTACK ZINC.HOWEVER, NOT USED FOR FOOD CONTAINERS, AS ZINC IS POISONOUS.

TIN PLATING:

PROCESS OF APPLYING A THIN LAYER OF TIN ON IRON ARTICLES.PROTECTS IRON SURFACES FROM RUSTING AND CORROSION.CAN BE USED IN FOOD CONTAINERS.HOWEVER, TIN PLATING OFFERS TEMPORARY PROTECTION, BECAUSE IF THE IRON GETS EXPOSED, MOISTURE ATTACKS IRON AS IT IS MRE ELECTROPOSITIVE.SO, RAPID RUSTING OCCURS.

SHERARDISING:

IT IS A PROCESS IN GALVANISATION. IRON ARTICLES ARE HEATED WITH ZINC DUST AT AROUND 673K IN A REVOLVING DRUM FOR SOME HOURS.THEN THE ARTICLES ARE REMOVED FROM THE DRUM AND HEATED TO 1073K.

A COATING OF ZINC IS FORMED ON THE IRON ARTICLE.

METALLIZING:

PROCESS OF GALVANISATION FOR LARGER IRON ARTICLES.MOLTEN ZINC IS SPRAYED ON IRON ARTICLES AND A FIRMLY ADHERENT COATING OF ZINC IS FORMED ON THEM.

ANODIZING:

THE PROCESS OF FORMING A PROTECTIVE ADHERENT FILM OF ALUMINIUM OXIDE (LESS THAN 0.00001 mm THICK) ON ALUMINIUM AND ITS ALLOYS BY ANODIC OXIDATION IS CALLED ANODISING.PROTECTS THE ARTICLE FROM CORROSION AND PROVIDES ELECTRICAL INSULATION.

CALORISING:

IT IS A PROCESS OF IMPREGNATING THE SURFACE OF IRON, COPPER, NICKEL, AND BRASS WITH ALUMINIUM.CALORISED METALS AND ALLOYS ARE RESISTANT TO ACIDS AND OXIDATION AT HIGH TEMPERATURES.

NITRIDING:

IT IS A PROCESS OF PREPARING SURFACE HARDENED STEEL.STEEL CONTAINING ALUMINIUM AND CHROMIUM IS HEATED AT ABOUT 873K FOR 60-70 HOURS IN PARTIALLY DISSOCIATED AMMONIA.ATOMIC NITROGEN PRODUCED IS ABSORBED BY STEEL TO FORM A HARD COATING OF METAL NITRIDES.

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