Enhancing structural stability and physical properties of silver added iron-MWCNT composite prepared by high energy ball milling and spark plasma sintering

This paper reports the beneficial effect of silver addition (~0.1 wt%) on the structural stabilization of multiwalled carbon nanotube (MWCNT) reinforced in iron matrix by way of high energy ball milling (HEBM) and spark plasma sintering (SPS). Silver added Fe - x wt% MWCNT (x = 1, 2, 3 and 4) composites were prepared by HEBM followed by SPS. Structural characterization of silver bearing composite powder and its sintered mass was carried out by XRD. The structural damage of MWCNT after HEBM was assessed by Raman Spectroscopy. As a support, Fourier Transform Infrared (FTIR) spectroscopic study was used to look into the bonding characteristics. Detailed microstructural studies by optical, field emission scanning (FESEM) and high-resolution transmission electron microscopy were employed to further assess structural stabilization and evolution of micro constituents during processing. Finally, magnetic and electrical properties of the composites were determined. It was revealed that minor addition of silver aids in restoration of the structural integrity of MWCNT in iron matrix composite. Moreover, it was noted that silver added composite could achieve a contamination free matrix–reinforcement interface. It is propounded that silver atoms tether MWCNT surface and behave like coating over MWCNTs. Conductivity of silver doped iron-4 wt% MWCNT composites exhibited a conductivity value higher than that of electrical conductivity grade (EC grade) aluminum. Saturation magnetization of silver doped Fe-MWCNT composite was increased by 25% over pure iron at 3 wt% MWCNT. The observed improvement in properties of composite is ascribed to tethering of silver particles at MWCNT surface; this gave rise to better interfacial bonding and the physical properties.