PROPERTIES OF BULK Fe–Ni/CNT NANOCOMPOSITES PREPARED BY MECHANICAL MILLING AND SINTERING

Abstract

The effects of carbon nanotubes (CNTs) on mechanical and tribiological properties of the NiFe /CNT composites prepared by high energy mechanical alloying and hot pressing, were investigated. Bulk samples were prepared by sintering of cold pressed (300 MPa) samples at 1040° C for 1 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and optical microscopy were employed for evaluation of the phase composition, surface morphology and porosities of the samples. The microhardness of as-milled Ni 3 Fe and NiFe powders reached to 720 and 650 VHN, respectively. The hardness of NiFe and Ni 3 Fe bulk samples reduced to 190 and 270 Vickers because of the grain growth during sintering and remaining porosity. The hardness of NiFe -CNT and Ni 3 Fe -CNT bulk samples reached to 360 and 400 Vickers, respectively. The friction and wear properties of the bulk samples were investigated under dry conditions using a pin-on-disk test rig under an applied load of 8 N. The wear rate, mass loss and friction coefficient of the composite samples remarkably reduced in comparison with NiFe and Ni 3 Fe matrix alloys which demonstrate effects of the CNTs on mechanical and tribiological behavior of the composites resulting from the excellent mechanical properties and unique topological structure of the CNTs.

Tribological Behavior of Carbon-Based Nanomaterial-Reinforced Nickel Metal Matrix Composites

“…The metal matrix composites reinforced with carbonaceous reinforcement are processed using various processing techniques, such as powder metallurgy, melting and casting, electrochemical deposition, and other novel approaches such as nanoscale dispersion and molecular-level mixing processes. Powder metallurgy is considered a convenient and versatile approach to fabricate near net-shaped bulk composite components with refined microstructure and provide excellent control over the quality and properties of the composites [26][27][28][29][30][31][32]. Previous studies have shown the viability of the ball milling technique to overcome the cohesive van der Waal forces and attain dispersion of carbonaceous reinforcement in the metal matrix.…”

“…In ball milling, the mixture of metal powder and carbonaceous reinforcement is subjected to repetitive impact forces during milling, which lead to the breakdown of the CNT/GNP agglomeration and increase the interfacial interaction between the reinforcement and metal matrix [33]. Results indicate that materials reinforced with solid lubricants and processed via powder metallurgical technique have extensive surface engineering applications, owing to the improvement in wear resistance and overall mechanical performance [27][28][29]. Alongside the uniform dispersion of reinforcement, strong interfacial interaction between the CNTs/GNPs and the metal matrix, with retained structural integrity, is critical for improving the load-bearing abilities.…”