In-situ Hot Pressing Synthesis and Corrosion Properties of High Pure Cr2AlC

Cr2AlC bulk material was prepared in-situ by hot pressing sintering using Cr3C2, Cr and Al as the starting materials. The samples were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). The reaction process was investigated by means of differential scanning calorimetry (DSC). The corrosion properties of Cr2AlC in the acid and alkali solutions were obtained by weight loss method. The XRD result shows that high purity Cr2AlC bulk material can be synthesized by hot pressing with n(Cr3C2): n(Cr): n(Al) = 0.5: 0.5:1.2 at 1350 degrees C for 2h under 30MPa. The XRD patterns in different temperatures suggest that the reaction process of starting materials is that Al melts at first, then Cr5Al8 generates at 700 degrees C, Cr2AlC is produced with the temperature elevation by the reaction of Cr5Al8 and Cr3C2 at last. SEM images of fracture faces of the sintered sample show the laminated and well plate-shaped grains with a mean particale size of 6.4 mu m. Cr2AlC exhibits low weight loss except immersion in the concentrated H2SO4 and HCl solutions. The weight loss is negligible after immersing samples in the concentrated and dilute NaOH solutions for 150d and the corrosion rates are only 0.4 and 0.7 mu m/a, respectively.