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Mater Sci Nanotechnol 2017 | Volume 1 Issue 2
allied
academies
Nanomaterials and Nanochemistry
November 29-30, 2017 | Atlanta, USA
International Conference on
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 ofmetal matrix
composites. In the present research, 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
fromthe samples and also for the uniformdispersionof polymer
derived ceramic particles. Microstructural observations carried
out using Field Emission Scanning ElectronMicroscopy (FE-SEM)
and Transmission Electron Microscopy (TEM) of the composite
indicated a uniform distribution of ~100 nm size particles of the
ceramic phase in the coppermatrix after FSP. Themicrostructure
during FSP evolved by discontinuous dynamic recrystallization.
In the composite, fine ceramic particles pinned the grain
boundaries, preventing grain growth resulting in a fine grain
(2 μm) structure being retained. FSPed Cu (processed with the
same process parameters as that of the composite) exhibited a
grain size of 100 μm compared to 400 μm in the base Cu. The
composite microstructure was characterized by equiaxed grains
with narrow grain size distribution and a high fraction (>80%) of
high angle grain boundaries. The nanocomposite exhibits a five-
fold increase in microhardness (260HV100) which is attributed
to the nano scale dispersion of ceramic particles. A mechanism
of shear has been proposed for the fracturing of PDC particles
during multi-pass FSP. The combined effect of grain refinement
and nano polymer derived ceramic particle incorporation lead
to a two-fold improvement in the proof stress of the composite
(201 MPa compared to 98 MPa of base copper). The ultimate
tensile strength improved by 33% and there was negligible drop
in the ductility of the composite when compared to base Cu.
Kocks-Mecking plot of the nano composite showed stage III of
work hardening.
Speaker Biography
Dr. Ajay Kumar P is currently working as a Post-Doctoral Researcher (Research
Associate) at the College of Engineering and Applied Science, University of Wisconsin-
Milwaukee (UWM) USA working in the area of developing metal matrix composite
program. Mainly he is working in the area of Advanced Surface Alloying of Plain Carbon
Steel to Stainless Steel Compositions during Manufacturing to improve Corrosion
Resistance of Components used in the Water Industry, Novel Surface Microstructure
and Low-Cost Surface treatments to reduce drag, Energy Consumption, and Corrosion
in Water Transport Systems, Waste Materials Reinforced Metal Matrix Composites for
Reducing Embodied Energy and Emissions, Graphene Based MMCs.
e:
Ajay Kumar P
University of Wisconsin-Milwaukee, USA
A novel in-situ polymer derived nano ceramic mmc by friction stir processing