GH4169表面电火花沉积NiCrAlY涂层的制备

Preparation of NiC rA lY coating electro-spark deposited on GH4169 alloy

采用电火花沉积技术在GH4169合金上制备不同铝含量的NiCrAlY涂层,通过真空退火处理高铝的NiCrAlY涂层厚度.测试电火花沉积涂层的增重曲线,用扫描电子显微镜观察涂层的组织,用X射线分析仪测试涂层的物相组成,研究退火以及不同涂层的元素含量对NiCrAlY涂层组织的影响规律.结果表明,高铝含量的NiCrAlY涂层存在涂覆极限厚度;退火处理后再次涂覆可进一步增加涂层厚度.在四次涂覆+退火后涂层达到极限厚度,厚度约为45μm.低铝含量的NiCrAlY涂层没有涂覆到极限厚度.对高铝含量的NiCrAlY涂层XRD结果表明,退火前主要物相为NiAl,退火后出现Ni3Al,涂层可以继续涂覆.低铝的NiCrAlY涂层物相为Ni_3Al,没有涂覆极限.和NiAl相比,Ni3Al和GH4169的线膨胀系数接近,使含有Ni3Al相的涂层能够继续涂覆.

NiC rA lY coatings with different Al contents were prepared by electro-spark deposition( ESD) on GH4169 alloy. For increasing the thickness of the coating,the coated samples were annealed in vacuum. The weight change of the coating with deposition time was tested. The microstructure was observed by a scanning electron microscope. The phases in the coatingswere investigated by an X-ray diffractometer. The influences of Al contents and annealing on the microstructure of the NiC rA lY coatings were investigated. The results show that there was a limit thickness for NiC rA lY coating with high Al content. After annealing,the thickness increased with further electro-spark deposition. After four times of annealing + ESD,the thickness of the coating reached the maximum value of about 45 μm,and its hardness was 440 HV. While there was no limit thickness for NiCrA lY coating with low Al content. The high Al content coating consisted of β-NiA l and α-Cr phases before annealing. After annealing,the Ni3 Al phase appeared because the thickness of coating increased continually. The NiC rA lY coating with low Al content was mainly composed of Ni3 Al phase. Compared with NiA l,the thermal expansion coefficient of Ni3Al is closer to that of GH4169,which is beneficial for the increase of thickness.