| Composite layers with a nickel matrix and a nano-sized Si3N4 disperse phase were examined. The composite layers were produced by two deposition techniques, i. e., the chemical reduction and the electrochemical method. A disperse phase of the silicon nitride with grain dimensions of the order of 15 nm was used for depositing the nickel composite coatings. The paper discusses the results concerning the morphology and diffraction patterns of the silicon nitride powder and its contents in the material of the composite coatings. The chemical compositions, the surface topography and the structure of the nano-crystalline composite Ni/Si3N4 and Ni-P/Si3N4 coatings were studied in details. The microstructures of the coatings were examined in a transmission electron microscope (TEM) and a scanning electron microscope (SEM) equipped with EDS suitable for local chemical analyses. The ceramic phase was also examined by the XRD and TEM techniques. A comparative analysis of the results shows that the deposition techniques used for producing the composite coatings have an important influence on the contents and distributions of the nano-dispersed phase within the surface composite layers. |
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