体外浸泡纯钛的表面腐蚀和ECAP的影响

采用在Ringer模拟体液静态体外浸泡的方法,研究工业纯钛试片经过一定时间的浸泡后的失重和表面形貌的变化。采用等通道径角挤压(ECAP)方法处理工业纯钛并与粗晶纯钛进行对比,对ECAP处理的TA9和粗晶TA9也做了对比。结果表明:纯钛在400℃ECAP处理后的微观组织形成具有明显方向性的板条状组织,ECAP纯钛表面沉积的Na Cl晶体数量大于粗晶Ti,TA9也表现出相似结果。纯钛的腐蚀机制是一种受到电偶腐蚀控制的均匀腐蚀,细晶组织导致电偶的数量增加。

Surface and Corrosion Study of CP-Ti by in-vitro Immersion Test and Effect of ECAP

Mass loss and surface morphology of commercially pure titanium (CP-Ti) were investigated by static immersion in vitro tests. Equal channel angular pressing (ECAP) process was applied to modify the microstructure of CP-Ti and the effect of the ECAP process on the mass loss and the surface morphology was studied. Another high crevice corrosion resistance alloy, Ti-0.2Pd (TA9) was also used for comparison. The results show that shear band is produced in the microstructure of ECAPed CP-Ti and the shear band interspaces are fine after two passes ECAP. Salt depositions are observed both on ECAPed CP-Ti and on coarse grained CP-Ti. The depositions are also found on ECAPed TA9 and coarse grained TA9. The ECAP process enhances the NaCl deposition on the surface and the shape of NaCl crystal is changed from grain shape formed on coarse grained CP-Ti to band shape formed on ECAPed CP-Ti. It is concluded that the corrosion mechanism of titanium is a uniform corrosion controlled by galvanic corrosion. Grain refinement leads to the increment in the number of galvanic.