Enhanced mechanical and wear properties of Al6061 alloy nanocomposite reinforced by CNT-template-grown core–shell CNT/SiC nanotubes

Abstract

Novel one-dimensional template-grown coaxial SiC@carbon nanotubes (SiC@CNTs) were fabricated using a chemical vapor deposition method. To facilitate the formation of SiC on CNT template, a molecular-level mixing process was used to coat the surface of commercial multiwalled carbon nanotubes (MWCNTs) by Fe 2 o 3. These Fe-CNTs were transformed into SiC@CNT nanotubes, which were then mixed with Al6061 alloy and consolidated by spark plasma sintering to obtain Al6061-SiC@ CNT nanocomposites. The addition of 5 vol% SiC@CNT resulted in 58% enhancement in Young's modulus and 46% enhancement in yield strength. Furthermore, the friction coefficient was reduced by 31% and the specific wear rate was reduced by 45%. The enhancement effect of Al6061-SiC@CNT on the mechanical and tribological properties was much greater than those of traditional nanoparticles, nanowires, and whiskers of SiCs. The extraordinary strengthening behavior of SiC@CNT, when compared with that of other SiC analogues, is attributed to the coaxial structure consisting of a SiC shell and CNT core. This coaxial structure enhanced the mechanical and tribological properties beyond that attainable with traditional SiC-derived reinforcements. Metal-matrix composites (MMCs) are increasingly being used in aerospace and automobile industries due to their excellent properties, such as elastic modulus, hardness, tensile strength, and wear resistance 1,2. Commonly used metallic matrices include Al, Mg, Ti, and their alloys. Generally, alloys are the preferred matrix materials for MMCs, due to possibilities to additional strengthening effects and flexible property design. For MMCs, fibers, whiskers, and particulates are commonly used as reinforcements 2,3. Amongst the alloy systems, Al6061 alloy is a popular choice as a matrix material, due to their high corrosion resistance and strength, which enables the material to be used in various structural applications, including automotive, construction, and marine engineering 4. The various properties of these alloys can be further enhanced by the addition of reinforcement materials, such as alumina (Al 2 O 3) and silicon carbide (SiC), which has led to the development of highly strong metal matrix composite materials with tailorable properties for specific applications. Among the ceramic reinforcements, SiC has been the most widely investigated 5-8. SiC has excellent properties including high electron mobility, high thermal conductivity, high tolerance for electrical breakdown, high hardness, and high mechanical strength 9. Many researchers have reported enhanced mechanical and wear properties of Al6061 alloys reinforced with SiCs 10-15. For example, Kumar et al. 12 reported fabrication of SiC particle reinforced Al6061 alloy composites by liquid metallurgy route via stir casting technique. In the present study, the authors suggest that the addition of SiC particles have significantly enhanced both mechanical and wear properties of the resulting composites. Yu

Evaluation of susceptor-assisted microwave-sintering-produced Al-Y2O3 composite material's compression and reciprocating wear performance

“…hybrid sintering impact on the composite material. Furthermore, according to the Hall-Petch relationship, increased hardness is associated with decreased grain size of the material [30,31].…”

Assessment of Mechanical and Tribological Behavior of AA6061 Reinforced with B4C and Gr Hybrid Metal Matrix Composites

“…The friction behavior of Al 6061-SiC-MWCNT was significantly affected by varying the load [17]. A scanning electron microscope (SEM) was used to perform a wear track microstructure analysis of AA5052 reinforced with 5% tungsten carbide, revealing that adding tungsten carbide reduced wear while maintaining constant input parameters [18]. AA6061-B 4 C powders with different concentrations of B 4 C (5, 10, and 15 wt.%) at 5% Gr were examined, and the sample containing 15 wt.% B 4 C exhibited the best wear characteristics, with a hardness value of 164 HV, significantly higher than the 33 HV for pure AA.…”

Microstructural and mechanical behavior of unique aluminum matrix composites reinforced with pre-synthesized Al/Cu core-shell particulates

“…In the first category, hard particles (ceramic: Al 2 O 3 , B 4 C, SiC, CNTs, TiB 2 , etc., and intermetallic: AlFe 3 , AlFeCu, etc.) are embedded in the aluminum matrix as reinforcement to achieve extraordinary strength [6][7][8][9][10][11][12][13][14][15][16][17]. However, with the increase in reinforcement volume fraction, the ductility of the composites significantly decreases due to the brittle nature of reinforcement and weak interfacial bonding be-tween reinforcement and matrix [18][19][20].…”