Song Zhenlun

Electrochemical Corrosion and Critical Pitting Temperature of S32750 Super Duplex Stainless Steel in NaCl Solution

The electrochemical corrosion behavior and critical pitting temperature (CPT) of S32750 super duplex stainless steel in 3.5%NaCl solution were investigated by electrochemical techniques. The morphologies of the steel before after pitting corrosion were observed by scanning electron mi- croscope. The CPT of the S32750 steel was identified as 71 ℃. A passive film could form on the steel surface when the solution temperature was below the CPT. While, when the solution tempera- ture was above the CPT, pitting corrosion occurred on the steel surface as the result of the break- down of the passive film due to the increase of the Cl - activity. Pitting corrosion became more seri- ous with the increasing temperature. Moreover, the corrosion models of the steel below and above the CPT were sketched respectively.

Effect of NiCrAlY Coating on Oxidation Resistance of Sm2Co17 Magnets at High Temperatures

采用直流磁控溅射方法在Sm2Co17磁体表面制备Ni Cr Al Y薄膜,分别探讨了Ni Cr Al Y薄膜防护的Sm2Co17(Ni Cr Al Y/Sm2Co17)磁体在500,600和700℃空气中的氧化行为,测试了磁体的氧化增重和磁性能,并用SEM,EDS和XRD对薄膜的微观形貌、化学成分和相组成进行表征。结果表明,Ni Cr Al Y薄膜在600℃以下可明显减缓O向Sm2Co17基体的扩散速率,提高Sm2Co17磁体的抗氧化性;当氧化温度升高到700℃,Ni Cr Al Y薄膜的防护效果有所下降。在高温氧化过程中,Ni Cr Al Y薄膜选择性氧化形成富Al2O3的致密氧化膜,可提升薄膜的高温抗氧化性能。