Characteristics of boronized Ti6Al4V alloy using boric acid based boronizing mixture

Abstract

Boronizing processes of Ti alloys are generally performed in atmosphere-controlled furnaces. In this study, it is aimed to carry out boronizing process under atmospheric conditions by using an alternative boronizing mixture containing boric acid and to better the surface characteristics of Ti6Al4V alloy by boronizing. The efficiency of the boronizing mixture was evaluated by performing boronizing at different process temperatures (900-1100 °C) and durations (12 and 20 h). Microstructural (OM, SEM) and chemical (XRD, EDS, XPS) analyzes were performed to characterize the boride layers formed on the surfaces of the boronized samples. As a consequence of these analyzes, it was found out that a two-phase boride layer (TiB2 + TiB) was obtained in the samples. In addition, in vitro tests were done for specifying the bioactivity of boronized samples. In order to determine the effect of boronizing on the corrosion resistance of Ti6Al4V alloy, corrosion tests were performed by the Tafel extrapolation method. The adhesion behavior of the boride layers was determined by the Daimler-Benz Rockwell C indentation test. As a result, boronizing studies have been performed successfully without atmospheric-controlled conditions and it has been defined that surface characteristics of the Ti6Al4V alloy have bettered through the boride layers formed on the alloy surface.