TiB₂-50Co coatings prepared by high velocity oxygen fuel and their properties

Three kinds of TiB₂-50Co coatings were fabricated by high velocity oxygen fuel method at three different oxygen flow rates, including 322, 402 and 462 L/min.The microstructure and phase structure of TiB₂-50Co coatings were analyzed by SEM and XRD. The microhardness was tested, and the properties of thermal shock resistance were tested by water quenching method. The corrosion resistance to molten Al-12.07wt%Si alloy and abrasive wear were investigated. Results show that the phases of three kinds of TiB₂-50Co coatings are TiB₂ and Co. Three kinds of TiB₂-50Co coatings have denser structure, especially the coating prepared under oxygen flow rate 322 L/min has much denser microstructure, the lowest porosity(1.76%) and the highest hardness value (558±90) HV_0.3. The coating prepared under oxygen flow rate 462 L/min has the worst thermal shock resistance performance with obvious microcrack. And the coatings have good durability in the molten Al-12.07wt%Si alloy after 60 h immersion test. The coatings have good abrasive wear performance after abrasive wear test with 6 N load, especially the coating prepared under oxygen flow rate 322 L/min has the best abrasive wear performance.