In this work, a novel duplex Ni-P/Ni-Mo-P coating upon the aluminum（Al） substrate was synthesized via an electroless plating, i.e., the binary Ni-P coating as a transition layer and the ternary Ni-Mo-P coating on th...In this work, a novel duplex Ni-P/Ni-Mo-P coating upon the aluminum（Al） substrate was synthesized via an electroless plating, i.e., the binary Ni-P coating as a transition layer and the ternary Ni-Mo-P coating on the top. It was found that the duplex coating was of a high hardness,large elastic modulus,low porosity and excellent corrosion resistance. In addition, experimental results revealed that for a total 20 μm coating thickness, the duplex coating with a 7 μm of the Ni-Mo-P coating exhibited the best corrosion resistance in 0.5 mol/L sulfuric acid solution, which was attributed to its compact structure and low porosity. This duplex Ni-P/Ni-Mo-P coating with a thin ternary Ni-Mo-P layer is expected to solve the problem of low deposition rate of ternary alloy coating and thereby may expand applications of Al and its alloys in the fields of machine manufacture and corrosion environment.展开更多
A Cr-Ni-Mo overlayer was deposited on the surface of compacted graphite iron（CGI）by the plasma transferred arc（PTA）alloying technique.The microstructure of Cr-Ni-Mo overlayer was characterized by optical microscop...A Cr-Ni-Mo overlayer was deposited on the surface of compacted graphite iron（CGI）by the plasma transferred arc（PTA）alloying technique.The microstructure of Cr-Ni-Mo overlayer was characterized by optical microscopy（OM）,scanning electron microscopy（SEM）equipped with energy dispersive spectroscopy（EDS）,and X-ray diffractometer（XRD）.Results show that the cross-section consists of four regions：alloying zone（AZ）,molten zone（MZ）,heat affected zone（HAZ）,and the substrate（SUB）.The microstructure of AZ mainly consists of cellularγ-（Fe,Ni）solid solution,residual austenite and a network of eutectic Cr7C3 carbide while the MZ area has a typical feature of white cast iron（M3C-type cementite）.The martensite/ledeburite double shells are observed in the HAZ.With decreasing the concentration of Cr-Ni-Mo alloys,the fracture mode changes from ductile in the AZ to brittle in the MZ.The maximum hardness of the AZ（450 HV0.2）is lower than that of the MZ（800 HV0.2）.The eutectic M3 C and M7C3 carbides increase the microhardness,while the austenite decreases that of the AZ.展开更多
基金supported financially by the National Natural Science Foundation of China (No.11174227)the National R&D Infrastructure and Facility Development Program of China (No.2005DKA10400)+1 种基金the Scientific Research Project of Liaoning Province Department of Education (No.L2010396)the Chinese Universities Scientific Fund
文摘In this work, a novel duplex Ni-P/Ni-Mo-P coating upon the aluminum（Al） substrate was synthesized via an electroless plating, i.e., the binary Ni-P coating as a transition layer and the ternary Ni-Mo-P coating on the top. It was found that the duplex coating was of a high hardness,large elastic modulus,low porosity and excellent corrosion resistance. In addition, experimental results revealed that for a total 20 μm coating thickness, the duplex coating with a 7 μm of the Ni-Mo-P coating exhibited the best corrosion resistance in 0.5 mol/L sulfuric acid solution, which was attributed to its compact structure and low porosity. This duplex Ni-P/Ni-Mo-P coating with a thin ternary Ni-Mo-P layer is expected to solve the problem of low deposition rate of ternary alloy coating and thereby may expand applications of Al and its alloys in the fields of machine manufacture and corrosion environment.
文摘A Cr-Ni-Mo overlayer was deposited on the surface of compacted graphite iron（CGI）by the plasma transferred arc（PTA）alloying technique.The microstructure of Cr-Ni-Mo overlayer was characterized by optical microscopy（OM）,scanning electron microscopy（SEM）equipped with energy dispersive spectroscopy（EDS）,and X-ray diffractometer（XRD）.Results show that the cross-section consists of four regions：alloying zone（AZ）,molten zone（MZ）,heat affected zone（HAZ）,and the substrate（SUB）.The microstructure of AZ mainly consists of cellularγ-（Fe,Ni）solid solution,residual austenite and a network of eutectic Cr7C3 carbide while the MZ area has a typical feature of white cast iron（M3C-type cementite）.The martensite/ledeburite double shells are observed in the HAZ.With decreasing the concentration of Cr-Ni-Mo alloys,the fracture mode changes from ductile in the AZ to brittle in the MZ.The maximum hardness of the AZ（450 HV0.2）is lower than that of the MZ（800 HV0.2）.The eutectic M3 C and M7C3 carbides increase the microhardness,while the austenite decreases that of the AZ.
