Structure And Properties Of Ni-W-B-CNTs Coatings Deposited On Al-Li Alloy

In this paper the Ni-W-B and Ni-W-B-CNTs coatings with different compositions were deposited on the 2195 aluminium alloy by composite electro-less plating technique successfully. The composition, microstructrue, corrosion and frictional behaviors were studied systematically.The composition and chemical states of Ni-W-B and Ni-W-B-CNTs coatings were characterized by X-ray photoelectron spectroscopy (XPS). The nanohardness and modulus of Ni-W-B and Ni-W-B-CNTs coatings were measured by mechanical properties microprobe. To observe surface morphology and roughness, atomic force microscope and scanning electric microscope were also used. Moreover, tribological and electrochemical corrosion behaviors have been investigation systematacially.The results showed that the surface morphology and roughness of the sample have greatly differences with the different technics. When the content of the Na2WO4 is low, the surface of the sample is charactered by ruleless shape. With the increase of the Na2WO4, the surface of the sample likes the cell and downy. And the coatings tend to compact and smooth. When the content of the DMAB is changed, the roughness shows nonmonotonously variation. In the coatings of the Ni-W-B-CNTs, C andW,Ni combine with the form of WC and Ni3C. Ni-W-B and Ni-W-B-CNTs coatings are mainly with amorphous structure. The corrosion of the Ni-W-B is better than the substrate. And the mechanism of the corrosion is pitting corrosion. Compared to the Ni-W-B coatings, the corrosion of the Ni-W-B-CNTs is enhaced greatly. And we cannot see any crack. The mechanism of the corrosion is also pitting corrosion. The hardness of the Ni-W-B and Ni-W-B-CNTs coatings is obviously higher than the substrate. But the friction coefficients are lower than the substrate. Compared to the Ni-W-B coatings, Ni-W-B-CNTs coatings have higher durable and carrying capacity.