ICI'S SULF BT SURFACE TREATMENT PROCESS REDUCES SCUFFING AND WEAR

IN OUR January/February issue, an article by F. D. Waterfall entitled “The Effect of Surface Chemistry and Hardness on Resistance to Scuffing” dealt with the Sulfinuz surface treatment process and the author concluded as follows:— “The Sulf BT Process was developed in France by Centre Stéphanois de Recerches Méchaniques Hydroméchanique et Frottement as an extension of the Sulfinuz process but without the drawback of the latter in respect of a relatively high operating temperature (570°C) causing softening of hardened parts. Unlike the latter it does not introduce carbon or nitrogen into the treated part but depends on the application of a tenacious scuffing resistant layer of iron sulphide about 200–400 micro‐inches thick to ferrous metal parts. This is done by making them anodic at 8–10 volts and a maximum current density of 0·20 amps/sq. in. whilst they are immersed in a molten salt bath containing sulphur compounds and maintained at a temperature of 200°C maximum.