Study on Hot Corrosion Resistance of In Situ Generated TiC and TiC + TiB Reinforced TB8 Titanium Matrix Composite by Powder Metallurgy

TiC and TiC + TiB were prepared through an in-situ reaction and powder metallurgy based on Ti-Mo-Nb-Al-Si matrix powder, CNTs (Carbon Nanotubes) and CNTs + B4C, which reinforces TB8 titanium matrix composites (TMCs). Firstly, the hot corrosion performance of three kinds of TiC (0, 2.5, and 5vol.-%) and one TiC + TiB (3.5 + 3.5vol.%) was investigated in Na2SO4(75wt.%)-NaCl(25 wt.%) saturated solution at 800°C. And then the corrosion kinetics indicated that the corrosion weight gain of 3.5vol.% TiC + 3.5vol.% TiC reinforced titanium matrix composite only reached 7.48 mg/cm2. Secondly, the features of corrosion scales formed on the composites were characterized based on x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The patterns of XRD illustrated the corrosion products are composed of TiO2, Al2O3, SiO2, Nb2O5, TiCl2, NaTiO2 and NaAlO2. SEM showed that the corrosion surface of TiC + TiB composite is the densest among the four composite materials (0 vol.% TiC, 2.5 vol.%TiC, 5 vol.%TiC, and 3.5 vol.%TiC + 3.5 vol%TiB). In addition, its corrosion layer thicknesses have little difference, which are 53, 46, 49, and 44 μm, respectively. Finally, the composite material with TiC + TiB has the best hot corrosion resistance, which verifies by the experimental analysis.