Characterisation of CoB–Co₂B coatings by the scratch test

Abstract

New results about the scratch practical adhesion-resistance of the CoB-Co 2 B/substrate system developed at the surface of CoCrMo (ASTM-F75) alloy were estimated. The boron diffusion on the surface of the cobalt alloy was conducted using the powder-pack boriding process at temperatures of 1223 and 1273 K with different exposure times for each temperature. The scratch tests over the surface of cobalt borided alloy were performed with a 200 micrometres Rockwell C diamond indenter considering a continuously increasing normal force for the entire set of experimental conditions of the boriding process. The worn tracks produced on the coating/substrate system were analysed by optical and scanning electron microscopy to estimate and identify the critical loads and failure mechanisms, respectively. The results indicated that the critical loads varied between 95 and 142 N as a function of the boride coating thicknesses with a development of various types of failure mechanisms over the surface of the coating/substrate system.

Growth Kinetics of CoB–Co2B Layers Using the Powder-Pack Boriding Process Assisted by a Direct Current Field

“…Also, the difference of Young´s modulus of the cobalt boride layers, the presence of cracks and porosity cause larger gradients along the depth of the CoB-Co 2 B layer. The state of residual stresses estimated on the cobalt boride layers is comparable with those reported in the literature for the CoB and Co 2 B layers obtained by the CPBP [7].…”

“…After the PBDCF process, the samples were subjected to metallographic characterization according to the method proposed by Bravo-Bárcenas et al [7], in order to reveal the microstructure of the cobalt boride layer.…”

“…In recent years, research on the boriding of cobalt alloys has advanced, specifically regarding the wear and oxidation properties of the cobalt boride layers [2][3][4]. In addition, the growth kinetics, some indentation properties, micro-abrasive wear resistance of CoB-Co 2 B, and the practical adhesion resistance of the cobalt boride layers formed on the surface of the CoCrMo alloy by means of the conventional powder-pack boriding (CPBP) process have been estimated [5][6][7].…”

Adhesion behaviour of borided AISI 4140 steel

“…The normal force (F N ) is constantly increased, generating a worn track with different failure mechanisms over the layer surface. The worn tracks are analysed in terms of the critical scratch load (L CN ) to estimate the characteristic failure mechanisms associated with visual microscopy inspections, CoF, and residual depth [17][18][19].…”

Effect of boronizing on the structural, mechanical and tribological properties of CoCrW dental alloy produced by selective laser melting

“…Also, some researchers studied the in vitro biocompatibility of Co-Cr alloys produced by SLM (Hedberg et al , 2014; Xin et al , 2012; Al Jabbari et al , 2014). Some of the researchers boronized Co-Cr alloys obtained by casting and studied the morphology and properties of the samples (Mu and Shen, 2010; Alvarez et al , 2013; Barcenas, et al , 2016). However, no study has yet been conducted on the mechanical and tribological effects of boronizing on CoCrW alloy produced by SLM.…”