Preparation and properties of a nanostructured NiCrC alloy coating for boiler tubes protection

Abstract

In this paper, a high-performance nanostructured NiCrC alloy coating was synthesized by HVAF spraying of nanostructured feedstock powder, which was prepared using cryogenic ball milling (cryomilling) method. The morphology and microstructure of the powder and coating were characterized by metallographic microscope, scanning electron microscope and transmission electron microscope. A Vickers microhardness tester was employed to determine the mechanical properties of the coating. The corrosion resistance was tested with thermogravimetric method, and the thermal stability of the coating was examined as well. The experimental results indicated that the nanostructured NiCrC coating possessed a very dense and uniform microstructure and exhibited sufficient thermal stability during long time heat treatment. Furthermore, the mechanical and anti-corrosion properties were enhanced so much compared with its conventional coarse-grained counterpart. The excellent performances make this HVAF sprayed nanostructured coating a hopeful candidate for improving boiler tubes protection. © 2008 The Japan Institute of Metals.