Preparation And Research On Coatings Containing Amorphous-Nanocrystalline Phase

In this paper, coatings containing amorphous and nanocrystalline phase were successfully prepared by electrothermal explosion spraying technique on 16Mn steel substrate. In addition, different process parameters (voltage of 4000V,4500V, 5000V and spray distance of 15mm,25mm,35mm) and different amorphous systems (FeBSiCrNbMnY, NiBSiCrNbMnY, FeAlBSiNiMnY) were studied.Microstructure, element distribution and composition of phase of coatings were investigated by scanning electron microscope, energy spectrum, micro hardness tester and X-Ray diffraction. However, the grain size of nano particle was calculated by Scherrer Formula, while the content of amorphous phase calculated by Pseud-Voigt function.Through the above means of experiments, process parameters of electrothermal explosion spraying and the choice of alloy systems were studied and discussed. As a result, the coatings containing amorphous and nanocrystalline phase had a metallurgical bonding with the substrate, good microstructure and average hardness (1137.84HV) far greater than it of the matrix. Spray voltage of 5000V and spraying distance of 35mm were the best process parameters, in that condition, the content of amorphous phase was up to 18.39%.The micro hardness was higher because nano-grain size was smaller. The improvement of hardness was due to the dispersion strengthened of amorphous-nanocrystalline. The capacity of amorphous formation in FeBSiCrNbMnY amorphous system is the best. FeBSiCrNbMnY coatings had the higher hardness and higher amorphous content than the other two. The hardness of the coating in NiBSiCrNbMnY was the lowest and the amorphous content was the lowest, too. Solid solution effects, the atomic size effect and the electronegativity difference between elements were the important factor in amorphous formation.