Salt Shower Nitriding Research Paper

Abstract

This paper examines on salt shower nitriding process with a specific end goal to enhance the wear conduct of the material. The hardness of the material is expanded up to 500% by this procedure. The specimens were nitrided at 523°c on three distinctive planning hours, for example, 60 minutes , 80 minutes, 120 minutes, 150 minutes and 180 minutes and named as SBN1, SBN2, SBN3, SBN4, SBN5 individually . A pin on plate machine is utilized to lead wear test, so that wear loss can be determined. The specimen are to be amplified by metallographic test, for example, nuclear magnifying lens and examining electron magnifying instrument . The best specimen is picked which decides the life of the material and enhances the better wear resistance.

Liquid nitriding compositions that does not contain a substantial amount of cyanate in the original melt , it must be aged before use in production. It is the surface air (oxygen)-to salt contact that oxidizes cyanide tocyanate. Molten salts in conventional baths should be aged by being held at 838 to 868 k for at least 12 hrs, and during age treatment no work should be placed in the salt. The ratio of cyanide content to cyanate content depends on the salt bath process and the salt bath composition . The typical commercial bath for nitriding consists of NaCN, NaCO3 and NaCNO mixture of 60-70% . The bath used in liquid pressure nitriding operates with a cyanate content of 15 to 20% and cyanide content of 30 to 35%. The liquid bath initially aged at a selective time temperature for combination to increase the cyanates content and then parts are immersed in the liquid for further processing. Salt bath nitrided components exhibit excellent sliding and running in properties as well as greater wear resistance. This nitriding improves wear resistance, lubricity, fatigue strength and corrosion resistance as a result of the presence of iron nitride compounds formed at the surface in integration to a zone of diffused nitrogen in solid solution with the base metal adjacent to the compound layer. Both of these zones are

This could be due to the presence ofhard compound layer of maximum thickness of 70 microns at the surface.

The combination action of strong adhesion, abrasion and severe plasticdeformation are the primary reasons for the continuous material loss in the untreated specimens. Whereas the wear on the nitrided specimen in mildform is dominated by oxidation wear resistance and micro abrasion.

In SEM analysis, salt bath nitridedspecimens reveals very minute microetch pits. They are visualized in the compound layer indicating the uneven distribution of nitrides. In plasma specimen, no wear was found. There is no peel of material, when compared to the other nitrided specimens, where as in untreated specimen, more peel of material occur. Also in salt bath nitrided samples, some cracks were found. This is due to the load acting over the specimen, sliding speed and variance sliding distance.

The results of this work confirm that nitriding has effectively improving its wear resistance. Comparing gas, salt bath, plasma nitrided samples, the wear resistance of plasma is highly