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Polymer Derived In-Situ Nano Metal Matrix Composites Obtained by Friction Stir Processing



Friction Stir Processing (FSP) is a solid state technique used for material processing. Tool wear and the agglomeration of ceramic particles have been serious issues in FSP of metal matrix composites. In the present study, FSP has been employed to disperse the nanoscale particles of a polymer-derived silicon carbonitride (SiCN) ceramic phase into copper by an in-situ process. SiCN cross linked polymer particles were incorporated using multi-pass FSP into pure copper to form bulk particulate metal matrix composites. The polymer was then converted into ceramic through an in-situ pyrolysis process and dispersed by FSP. Multi-pass processing was carried out to remove porosity from the samples and also for the uniform dispersion of polymer derived ceramic particles. Microstructural observations were carried out using Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) of the composite. The results indicate a uniform distribution of ~100 nm size particles of the ceramic phase in the copper matrix after FSP. The nanocomposite exhibits a five fold increase in microhardness (260HV100) which is attributed to the nano scale dispersion of ceramic particles. Tensile properties of the produced metal matrix composite were significantly higher than processed plain specimen and base metal.

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