粘结剂成分对Ti(C,N)基金属陶瓷腐蚀行为的影响

Effect of binder composition on corrosion behavior of Ti(C,N)-based cermets

摘要:

研究了含38 wt% Ni或Ni–20Cr粘结剂的2种Ti(C,N)基金属陶瓷在0.2 M H2SO4和0.2 M NaOH溶液中的室温腐蚀行为。在0.2 MH2SO4溶液中，2种金属陶瓷的腐蚀行为和耐蚀性存在一些明显的差异：与以Ni作粘结剂的金属陶瓷不同，以Ni–20Cr作粘结剂的金属陶瓷浸泡过程中表面自发生成NiO、Ni(OH)x(SO4)y、Cr2O3和Cr(OH)3，致使粘结相溶解十分缓慢；动电位极化过程中不发生钝化，伪钝化后电流密度增加较快。在0.2 M NaOH溶液中，2种金属陶瓷的腐蚀行为和耐蚀性无明显差异：浸泡过程中陶瓷晶粒溶解十分缓慢，同时生成NiOOH和Cr6+化合物；动电位极化过程中不发生钝化，但发生伪钝化。

Abstract:

Corrosion behavior of two Ti(C,N)-based cermets with 38 wt.% Ni or Ni–20Cr binder was investigated in 0.2 M H₂SO₄ and 0.2 M NaOH solutions at room temperature. In 0.2 M H₂SO₄ solution, there were significant differences in corrosion behavior and resistance between both cermets. For cermet with Ni–20Cr binder, binder phase was very slowly dissolved during immersion, mainly due to that the spontaneous formations of NiO, Ni(OH)_x(SO₄)_y, Cr₂O₃ and Cr(OH)₃, and no passivation occurred and current density steeply increased beyond the pseudo-passive region during potentiodynamic polarization, differing from cermet with Ni binder. By contrast, in 0.2 M NaOH solution, there were no significant differences in corrosion behavior and resistance between both cermets. For both cermets, ceramic grains were very slowly dissolved during immersion, accompanied by the formations of NiOOH and Cr^₆₊ compound, and no passivation but pseudo-passivation occurred during potentiodynamic polarization.