Improvement of high temperature oxidation behavior of Cr3C2-20 wt % Ni cermets by adding 1 wt % Mo.

Cr 3 C 2 -20 wt % Ni cermets were prepared by Cr, C and Ni mixed powders using high energy milling and reactive sintering method comparing with the one contains 1 wt % Mo addition. Isothermal oxidation experiments were conducted at 800 °C in the static air from 10 h to 100 h using cyclic oxidation method. The high temperature oxidation behavior of Cr 3 C 2 -20 wt % Ni cermets effected by 1 wt % Mo addition was investigated. After 100 h oxidation, the oxidation weight increase and parabolic rate constants of the one with Mo decreased from 0.126 to 0.080 mg/cm 2 and 4.41 × 10 −12 to 1.78 × 10 −12 kg 2 /m 4 ·s, respectively. Generally, two positive effects were found by Mo additive, such as increasing the Cr atom concentration in the Ni and minimizing the formation of NiO during oxidation. The oxidation products of the cermets changed from forming the Cr 2 O 3 and NiCr 2 O 4 to that only forming Cr 2 O 3 after adding molybdenum element. Pure Cr 2 O 3 possessed better and denser crystal structure than that of NiCr 2 O 4 . The cermets were protected due to the formation of the dense oxide films on the surfaces of the substrates at high temperature. This novel mechanism was of academic influence and could serve as a guide for the further research on Cr 3 C 2 - 20 wt % Ni cermets. [ABSTRACT FROM AUTHOR]