Preparation Of High-aluminum Bronze Powder And Study Of Its Microstructure And Properties Of Layers

In the present research work, a kind of novel high-aluminum bronze alloy (Cu-14Al -X) powders was produced by gas atomization in nitrogen atmosphere. The main composition of Cu-14Al-X is Cu70～80%, Al12～16%, Fe2.0～4.0 %, the rest is Mn, Ni ,Co etc. The influence of gas pressure on the shape and granularity of the powder was discussed. It was found that the powders which were produced with proper gas pressure are fine, spherical, compact, regular and well distributed. And a rather higher gas pressure is benefit for the quality of Cu-14Al-X powders.Two kinds of Cu-14Al-X alloy coatings were prepared on the 45 carbon steel substrate by plasma spray welding technique and laser cladding technique respectively. The microstructure,phase structure and interface structure of the Cu-14Al -X alloy coatings were investigated with SEM, EPMA, FEGSEM, EDS and XPS. The microstructure, chemical component and properties of Cu-14Al-X alloy coatings were studied by examining and evaluating in hardness, wear resistance etc. It was found that the microstructure of laser cladding layer is smaller and more homogeneous and compact than plasma spray weld coating .The hardness of coating and bond strength between the coating and the substrate of laser cladding layer are also higher than the plasma spray weld coating.The formation and its microstructures of Cu-14Al-X alloy layers have the characteristics of rapid solidification. The microstructure at the layer bottom is the typical extension growth on the plane basis, the dendrite crystal is coarser. The microstructure at the top and middle of layer is the regular pine-tree eutectic crystal and small cell and column crystal, respectively. The crystalline anisotropy is a main factor to influence the crystal growth form at the middle of the layer.