Abstract: The corrosive behavior of Ti/Al dual coating on uranium prepared by magnet-sputtering ion plating technique was investigated under the condition of 0.05MPa O2, H2O or HCl atmosphere at 200-500℃. The depth profile of corrosive elements in Ti coating was analyzed by Auger Electron Spectroscopy(AES). The stress distribution in the dual coatings was evaluated by the finite element method during rising and cooling processes. The reaction temperature of the Ti/Al dual coating with O2, H2O and HCl gases was found to be decreased. The Ti/Al dual coating on uranium was spalled at Al/U interface after hot corrosion in O2 and H2O atmosphere, and Ti coating was separated from Ti/Al interface in HCl atmosphere. Both Al/U and Ti/Al interfaces of the Ti/Al dual coating on uranium are the worst anti-corrosion region against O2, H2O and HCl gases. The stress leads to failure of the dual coating at the interface after O or Cl element diffuses into the interface and reacts with the metal.
Corrosion behavior of Ti/Al dual coatingon uranium in corrosive gas
Abstract:
The corrosive behavior of Ti/Al dual coating on uranium prepared by magnet-sputtering ion plating technique was investigated under the condition of 0.05 MPa O2, H2O or HCl atmosphere at 200500 ℃. The depth profile of corrosive elements in Ti coating was analyzed by Auger Electron Spectroscopy (AES) . The stress distribution in the dual coatings was evaluated by the finite element method during rising and cooling processes. The reaction temperature of the Ti/Al dual coating with O2, H2O and HCl gases was found to be decreased. The Ti/Al dual coating on uranium was spalled at Al/U interface after hot corrosion in O2 and H2O atmosphere, and Ti coating was separated from Ti/Al interface in HCl atmosphere. Both Al/U and Ti/Al interfaces of the Ti/Al dual coating on uranium are the worst anti-corrosion region against O2, H2O and HCl gases. The stress leads to failure of the dual coating at the interface after O or Cl element diffuses into the interface and reacts with the metal.
图3 在0.05 MPa O2气氛中腐蚀1 h后 铀表面Ti/Al复合镀层的表面形貌 Fig.3 Surfacial morphologies of Ti/Al dual coating on uranium after 1 h corrosion in 0.05 MPa O2 atmosphere at different temperatures (a) —300 ℃; (b) —500 ℃, Ti side of spalled dual coating; (c) —500 ℃, Al side of spalled dual coating
图4 在0.05 MPa O2气氛中腐蚀1 h后O在 Ti和Ti膜中的俄歇电子能谱深度分析 Fig.4 AES depth profile of oxygen in bulk Ti (a) and Ti coating (b) corroded in 0.05 MPa O2 atmosphere for 1 h
图5 300 ℃时在0.05 MPa H2O气氛中腐蚀1 h后 铀表面的Ti/Al复合镀层的表面形貌 Fig.5 Microstructures of Ti/Al dual coating on uranium after 1 h corrosion in 0.05 MPa H2O atmosphere at 300 ℃ for 1 h (a) —Uranium side of spalled dual coating; (b) —Ti side of spalled dual coating; (c) —Al side of spalled dual coating
图6 不同温度时0.05 MPa HCl气氛中腐蚀1 h后 铀表面Ti/Al复合镀层的表面形貌 Fig.6 Microstructures of Ti/Al dual coating on uranium after 1 h corrossion in 0.05 MPa HCl atmosphere at different temperatures (a) —200 ℃; (b) —300 ℃
图7 腐蚀冷却后试样的环向应力分布 Fig.7 Circumference stress distribution after corrosion and cooling (a) —Stress at interface during heating and cooling; (b) —Residual stress distribution along axial direction of specimen after cooled to room temperature