•A new type of SiC–Zirconia–Glass (SZG) coating for C/C composites was designed and prepared by slurry method.•The SCG coated C/C composites show excellent anti-oxidation properties at 1123–1273 K.•Oxidation mechanisms of the as-produced samples were discussed in detail.A novel type of SiC–Zirconia–Glass coating for carbon/carbon(C/C) composites was designed and prepared by slurry method and their microstructure and oxidation behavior at temperatures of 1123–1273 K were investigated. The results show that the weight loss rate of samples was below 1.5% after oxidation of 70 h and have excellent mechanical properties remaining after a 1123–1273 K oxidation process. The relationship between the weight loss rate and oxidation time can be fitted to an exponential curve and the reaction activation energy of diffusion through the coating cracks was 16.68 kJ mol−1. It was found that the oxidation model of SiC–ZrO2–Glass coated C/C composites was not exactly follow to Arrhenius's law during temperature of 1123–1273 K and has characteristics of defective oxidation.Oxidation mechanism of the coated C/C composites. Early stage (a), mid-stage (b) and later stage (c) of oxidation.Download high-res image (95KB)Download full-size image

The effect of heat treatment on the tensile creep behavior of duplex titanium alloy Ti–6.3Al–1.6Zr–3.4Mo–0.3Si (TC11) at 500 °C, 300 MPa, as well as the tensile creep of heat-treated TC11-2 alloys over the temperature range 450–550 °C at stress range 300–450 MPa have been investigated in detail, by means of curve measurements and microstructure observation. At 500 °C and 300 MPa, the TC11 alloys with duplex microstructure exhibited less creep deformation and strain rates than basket-weave microstructure, and heat treatment at condition of 970 °C/1 h/AC+530 °C/6 h/AC has the best creep performance. TEM analysis indicates that the creep in duplex structure alloy is controlled by dislocation climb (Metal-type or Class II alloy creep), and changes to a jogged-screw creep model in basket-weave structure. For heat-treated TC11-2 alloy, the corrected activation energies between 65 kJ/mol and 188 kJ/mol, and stress exponents in the range 1–3.8 were obtained. At 450 °C, small apparent stress exponent (equal ∼1) as well as low activation energies suggested that the creep is controlled by double mechanisms of Harper–Dorn dislocation creep and diffusion type creep. At 500 °C and 550 °C, the higher stress exponents and apparent activation energies indicated that creep is controlled by climb of dislocation. The second phases, mainly (Ti,Zr)5Si3, inhomogeneously precipitated from both primary α grain and α/β lath interface, which has limited effects on hindering the movement of dislocations during creep.