Abstract
A family of TiC–stainless steel ceramic–metal composites, or cermets, has been developed in the present study, using steel grades of 304 L, 316 L, or 410 L as the binder phase. Melt infiltration was used to prepare the cermets, with the steel binder contents varying between 10–30 vol. %. The corrosion behaviour was evaluated using a range of electrochemical techniques in an aqueous solution containing 3.5 wt. % NaCl. The test methods included potentiodynamic, cyclic, and potentiostatic polarisation. The corroded samples were subsequently characterised using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), while the post-corrosion solutions were analysed using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the residual ionic and particulate material removed from the cermets during electrochemical testing. It was demonstrated that the corrosion resistance was enhanced through decreasing the steel binder content, which arises due to the preferential dissolution of the binder phase, while the TiC ceramic remains largely unaffected. Increasing corrosion resistance was observed in the sequence TiC-304 L > TiC-316 L > TiC-410 L.
Highlights
Titanium carbide (TiC)-based ceramic-metal composites, or cermets, have become more widely used in demanding wear applications due to their improved capabilities when compared with more traditional “hardmetals” based on tungsten carbide with a cobalt binder (WC-Co) [1]
By comparing the corrosion performance of “pure” WC and WC prepared with 5 wt. % Co, the corrosion resistance of the WC-Co materials decreased, which was attributed to the preferential dissolution of the Co binder in the composite
All of the samples were densified in excess of 99% of theoretical
Summary
Titanium carbide (TiC)-based ceramic-metal composites, or cermets, have become more widely used in demanding wear applications due to their improved capabilities when compared with more traditional “hardmetals” based on tungsten carbide with a cobalt binder (WC-Co) [1]. TiC-based cermets have several properties that typically exceed those of WC, such as increased hardness and toughness, as well as a lower mass; the density of WC is approximately three times that of TiC [2]. In terms of cermet corrosion behaviour, it is invariably noted that the incorporation of a metallic binder with the ceramic matrix phase degrades the performance [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. Other authors have reported evidence of dissolution of the Co binder [7,10], and it was confirmed that the loss of the metal binder governs the corrosion behaviour of WC-Co cermets, Metals 2018, 8, 398; doi:10.3390/met8060398 www.mdpi.com/journal/metals
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