稀土改性Ni-Al复合涂层的制备及显微组织

Preparation and Microstructure of Rare Earth Modified Ni-Al Composite Coating

稀土镍铝复合涂层能大幅提高高温构件的抗氧化性和耐腐蚀性,广泛应用于高温零部件。首先在P92钢表面进行镀镍,然后在渗铝剂中加入不同种类、含量的稀土(CeCl3、SmCl3),利用粉末包埋渗铝技术,在P92钢表面制备稀土Ni-Al复合涂层。利用LSCM、SEM对复合涂层的结构、形貌、厚度进行对比分析;利用EDS对复合涂层的元素成分进行分析,并采用XRD分析复合涂层的表面物相。结果表明:两种稀土元素均可起到催渗效果,并减少涂层缺陷。渗铝剂中稀土CeCl3和稀土SmCl3的添加量均为2%时,所得复合涂层的渗层均匀致密,质量最佳,渗铝层平均厚度分别为50.4、48.1μm;当添加量增加时(4%、6%),两种涂层的渗铝层厚度均减少,且疏松、孔洞等现象更加明显。稀土元素的种类及含量不改变复合涂层的表面物相,均为Ni2Al3和Ni。

The rare earth nickel-aluminum composite coating can greatly improve the oxidation resistance and corrosion resistance of high temperature components,which is widely used in high temperature parts.Nickel plating was first carried out on the surface of P92 steel,and then different kinds of rare earth(CeCl3,SmCl3)were added to the aluminizing agent,the rare earth Ni-Al composite coating was prepared on the surface of P92 steel by powder-embedded aluminizing technology.The structure,morphology and thickness of the composite coating were characterized by LSCM and SEM.The elemental composition of the composite coating was analyzed by EDS,and the surface phase of the composite coating was analyzed by XRD.The results show that both rare earth elements can promote the penetration and reduce the coating defects.When the addition amount of rare earth CeCl3 or rare earth SmCl3 in the aluminizing agent is 2%,the aluminized layer of the composite coating is uniform and dense,the coating quality is best,and the average thickness of the aluminized layer is 50.4μm and 48.1μm,respectively.When the addition amount is increased(4%,6%),the thickness of the aluminized layer of both coatings decreases,and the phenomenon of looseness and pores is more obvious.The type and content of rare earth elements do not change the surface phase of the composite coating,which are Ni2Al3 and Ni.