Effect of Compression Process of MWCNT-Reinforced Al6061 Powder on Densification Characteristics and Its Mechanical Properties

Hyung Seo,Long Jiang,Chung Kang,Chul Jin

doi:10.3390/met7100437

Abstract

In this paper, aluminium-based (Al6061) composites with 1, 3, 5, 7, and 10 vol % of multi-walled carbon nanotubes (MWCNTs) are investigated. The composites are fabricated by high-energy ball milling, cold-compacting at room temperature under compacting pressures of 400–1600 MPa, and sintering at 620 °C in an argon gas atmosphere. Thereafter, the hardness and microstructure of MWCNTs/Al6061 composites are examined. Further, to improve the relative density and hardness level of the complex material, open-die forging is performed after cold-compacting under 1 GPa pressure at room temperature and sintering at 620 °C. The open-die forging parameters include 1, 3, 5, 7, and 10 vol % MWCNTs/Al6061, and Al6061. The experimental results show that the mechanical properties of the composites are significantly superior to that of the Al6061 alloy after undergoing cold-compacting, sintering, and open-die forging.

Highlights

Multi-walled carbon nanotubes (MWCNTs), first discovered by Iijima [1] in 1991, exhibit excellent electric conductivity, thermal conductivity, coefficient of thermal expansion, corrosion resistance, and wear resistance [2,3,4]
The resultsCharacteristics indicated that relative density based on compaction pressure at room temperature was prominently low, given addition of multi-walled carbon nanotubes (MWCNTs), when compared withatthe green density ofwas the
The results indicated thatthe relative density based on compaction pressure room temperature existing Al6061

Summary

Introduction

Multi-walled carbon nanotubes (MWCNTs), first discovered by Iijima [1] in 1991, exhibit excellent electric conductivity, thermal conductivity, coefficient of thermal expansion, corrosion resistance, and wear resistance [2,3,4]. Pérez-Bustamante et al [5] examined a technology that successfully manufactured Al-MWCNT composite material via mechanical milling, sintering, and hot extrusion. The study investigated process conditions under which the mechanical properties of the carbon nanotube (CNT) remained unchanged despite ball milling and hot extrusion. It was reported that the elongation rate of CNT/Al composite material increased by ~0.36 compared with that of extruded pure Al. Tensile strength improved up to 297.7 MPa, corresponding to ~2.5 times that of pure Al. the study reported the presence of an adverse effect, in which the mechanical properties of the material downgraded owing to the high-temperature oxidation of CNTs. Kuzumaki et al [7] introduced a technology that manufactured CNT/Al composite materials using hot compaction and extrusion processes.

Methods

Results

Conclusion