Effect of Mo₂C on electrochemical corrosion behavior of Ti(C,N)-based cermets

DONG Guang-biao(董广彪)¹, XIONG Ji(熊计)¹, YANG Mei(杨梅)², GUO Zhi-xing(郭智兴)¹, WAN Wei-cai(万维财)¹, YI Cheng-hong(易成红)¹

(1. School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China;
2. College of Materials and Chemistry & Chemical Engineering,
Chengdu University of Technology, Chengdu 610059, China)

Abstract:The electrochemical corrosion behavior of Ti(C,N)-based cermets with different Mo₂C additions was investigated in freely aerated 10% H₂SO₄ and potentiodynamic polarization of all the materials was conducted from -0.5 to 1.5 V. There are two passive regions for all polarization curves. The first should be attributed to passive film formation due to Ti(C,N), while the second may be due to the presence of Ni. Corrosion current density increases with Mo₂C content increasing, from 2.06×10^-3 to 6.70×10^-3 mA/cm². It is indicated that the corrosion resistance of Ti(C,N)-based cermets decreases with the increase of Mo₂C addition. A skeleton of Ti(C,N) gains is observed after dissolution of Ni. The inner rim of cermets, rich in Mo₂C, is corroded along with Ni binder and is more serious with the increase of Mo₂C content. The secondary carbide Mo₂C can be oxidized and dissolved in sulphuric acid.

Key words:Ti(C,N)-based cermets; Mo₂C; electrochemical corrosion