Slurry erosion-corrosion wear behavior in SiC-containing NaOH solutions of Mo2NiB2 cermets prepared by reactive sintering

The slurry flow unit, such as coal-mining industry, erosive wear and erosion-corrosion can cause high rates of material loss, particularly in the hydrotransport system where corrosive slurries are encountered. Stainless steel, Metal Matrix Composites (MMCs) and so on, comprising a ductile binder with a reinforcing hard phase, are seeing greater applications as coatings and hard facing for critical components, where there is a requirement for high durability. In this paper, the erosion-corrosion performance of Mo2NiB2-based cermets applied by the reaction sintering process is evaluated. Three cermets, with varying volume fraction of Mo2NiB2 phase range, all with a Ni binder, have been considered. The microstructure and properties of Mo2NiB2-based cermets are investigated and discussed. The influence of volume fraction of Mo2NiB2 phase on the erosion and erosion-corrosion resistance is researched under alkaline conditions. Results reveal that the increasing of boron percent along with Mo2NiB2 phase pile up. Meanwhile, the hardness has direct relationship with the volume fraction of Mo2NiB2. The Mo2NiB2 phase plays an important role in wear behavior. The effect of Mo2NiB2 phase volume fraction on erosion-corrosion only containing NaOH solution of Mo2NiB2-based cermets is different from that on erosion containing both NaOH solution and SiC. It is advantageous for the corrosion resistance to contain more Mo2NiB2 phase. In alkaline slurry impact, the cermets with less Mo2NiB2 phase deteriorate largely due to corrosion which decreases the mechanical properties and speeds up the total loss of material. In alkaline slurry with SiC particles, the weight gain is produced by the synergistic effect of erosion and corrosion on the contrary. When the volume fraction of Mo2NiB2 is low, corrosive production is the main cause of weight gain due to increasing interference between impinging and reflected erodent. The Mo2NiB2 phase is more, the corrosion resistance is higher and the corrosive production is much less.