碳纳米管对Ni60激光熔覆层的耐蚀性影响

利用自动送粉激光熔覆技术,在A3钢表面进行了Ni60合金添加碳纳米管的激光熔覆实验,采用静态浸泡法对相同工艺条件下获得的纯Ni60熔覆层和碳纳米管/镍基熔覆层的耐腐蚀性进行研究,在光学显微镜下观察样品表面腐蚀形貌,并对碳纳米管/镍基熔覆层的腐蚀机理进行了分析.结果表明:当碳纳米管的含量为0.3 wt%时,碳纳米管/镍基激光熔覆层的耐腐蚀性能最好,与纯Ni60激光熔覆层相比,耐腐蚀性提高1倍多.碳纳米管/镍基激光熔覆层耐腐蚀的原因在于熔覆层保留的碳纳米管使熔覆层更加致密,隔离了腐蚀介质,促进了镍基合金的钝化,从而提高了熔覆层的耐蚀性;同时,熔覆层中保留下来的碳纳米管和被分解的碳纳米管与金属基体形成碳化物,作为增强相均匀弥散在熔覆层中,它们的存在阻止了腐蚀坑的长大,因而蚀坑较小,耐腐蚀性得到提高.

Effect of carbon nanotubes on the corrosion resistance of laser-clad Ni60 alloy coatings

The experiments of laser-clad Ni60 alloy powder doped with carbon nanotubes(CNTs) have been carried out.The corrosion resistance of the Ni60 coatings and the CNTs/Ni60 coatings which was obtained under the same processing parameters was studied using the gravimetricm method.Optical microscope was used to observe the morphology of the samples.The corrosive mechanism of the CNTs/Ni60 coatings was also analyzed.The results show that the corrosion resistance of the CNTs/Ni60 coating doped with 0.3wt% CNTs is best and adds up 2 times compared with Ni60 coatings.The enhance ment of the corrosion resistance laser dadoling of the CNTs/Ni60 coatings is due to that the reserved carbon nanotubes in the coatings segregate the corrosive mediun and promote Ni-based alloy passivation,the formed phases of the carbide and the reserved carbon nanotubes homogenous distribution in the claddings resist the corrosion.