Wear and Surface Characterization of Boronized Pure Iron

Abstract

This research investigates the morphological nature and tribological behavior of boronized pure iron using experiments combined with theoretical analysis. Samples studied were 99.97% purity iron boronized for 4h at 800°C, 875°C and 950°C, respectively. Diffusion of the borided layer was analyzed by measuring the extent of penetration of the boride to sublayers as a function of boriding time and temperature. The distribution of alloying elements from surface to interior was determined by using rf-glow discharge optical emission spectrometry. It was found that boron concentrated in the layer and the diffusion of B atoms was deeper than the layer itself. In tribological tests, friction and wear behavior under dry rolling with sliding (pseudo-rolling) and dry pure sliding conditions was investigated. The wear experiments were conducted using a modified linear reciprocating tribometer. A scanning electron microscope and atomic force microscope were used for worn surface characterization. It was found that boronizing at 875°C exhibited the best wear resistance among the samples tested. Higher wear resistance was correlated with growth of boride crystals along stronger (002) orientation. Surface grain size distribution after the boriding process was identified as an important factor for wear resistance. Different fracture and wear modes were investigated. Analysis of the wear debris gave an insight into the operative wear mechanisms. This research is beneficial in optimizing the parameters of the boronizing process to achieve better wear resistance under different contact modes.