Magnesium matrix composite reinforced by nanoparticles – A review

In this study, mechanical properties and corrosion resistance of AZ61 and AZ91 magnesium matrix composites reinforced with 01, 0.2, and 0.5 wt% carbon nanotubes (CNTs) were investigated, detailly. CNTs have been successfully synthesized with 15–20 nm diameters by chemical vapor deposition (CVD) method and then, added to magnesium alloys by using the powder metallurgy (PM) technique. The composite compacts were consolidated by cold-pressing under 500 MPa pressure and sintered for 2 h at 500 °C under Ar atmosphere. The characterization studies of the unreinforced alloys and composites were carried out by scanning and transmission electron microscopes (SEM, TEM), electron dispersive spectroscope (EDS), Raman spectroscopy, and X-ray diffraction. The mechanical properties and corrosion behaviors of the composites have been compared with compression tests and potentiodynamic scanning (PDS) techniques, respectively. The results showed that the effect of CNTs reinforcement on strength increase was greater in AZ61 series samples than AZ91-based composites. The corrosion results of the presented study showed that the composites reinforced with lower CNTs (such as 0.1 or 0.2 wt%) and unreinforced alloys had better corrosion resistance than high CNTs (such as 0.5 wt%) containing structures. However, the most resistant structure to the corrosion for both AZ61 and AZ91 alloys were obtained in the composites reinforced with 0.2 wt% CNTs.

Carbon nanotube (CNT) reinforced magnesium matrix composites: The effect of CNT ratio on their mechanical properties and corrosion resistance

Abstract Metal matrix nanocomposites (MMNCs) become irreplaceable in tribology industries, due to their supreme mechanical properties and satisfactory tribological behavior. However, due to the dual complexity of MMNC systems and tribological process, the anti-friction and anti-wear mechanisms are unclear, and the subsequent tribological performance prediction and design of MMNCs are not easily possible: A critical up-to-date review is needed for MMNCs in tribology. This review systematically summarized the fabrication, manufacturing, and processing techniques for high-quality MMNC bulk and surface coating materials in tribology. Then, important factors determining the tribological performance (mainly anti-friction evaluation by the coefficient of friction (CoF) and anti-wear assessment with wear rate) in MMNCs have been investigated thoroughly, and the correlations have been analyzed to reveal their potential coupling/synergetic roles of tuning tribological behavior of MMNCs. Most importantly, this review combined the classical metal/alloy friction and wear theories and adapted them to give a (semi-)quantitative description of the detailed mechanisms of improved anti-friction and anti-wear performance in MMNCs. To guarantee the universal applications of these mechanisms, their links with the analyzed influencing factors (e.g., loading forces) and characteristic features like tribo-film have been clarified. This approach forms a solid basis for understanding, predicting, and engineering MMNCs’ tribological behavior, instead of pure phenomenology and experimental observation. Later, the pathway to achieve a broader application for MMNCs in tribo-related fields like smart materials, biomedical devices, energy storage, and electronics has been concisely discussed, with the focus on the potential development of modeling, experimental, and theoretical techniques in MMNCs’ tribological processes. In general, this review tries to elucidate the complex tribo-performances of MMNCs in a fundamentally universal yet straightforward way, and the discussion and summary in this review for the tribological performance in MMNCs could become a useful supplementary to and an insightful guidance for the current MMNC tribology study, research, and engineering innovations. 

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Metal matrix nanocomposites in tribology: Manufacturing, performance, and mechanisms

Tribological behaviour of self-lubricating Mg matrix composites reinforced with silicon carbide and tungsten disulfide

This article statistically investigates the effect of various parameters such as material factors: silicon carbide (SiC) fraction, graphite (Gr) fraction and mechanical factors: normal load, sliding distance and speed on the sliding wear rate of self-lubricating AZ91D-SiC-Gr hybrid magnesium composites. The self-lubricating hybrid composites were fabricated using advanced vacuum assisted stir casting process. The sliding wear tests have been performed under dry conditions on pin-on-disc tribometer at 10-50 N loads, 1-3 m/s sliding speed and 1000-2000 m sliding distance. It has been examined that hybrid composites yielded improved wear resistance with reinforcement of SiC and solid lubricant graphite. ANOVA and signal-to-noise ratio investigation indicated that applied load was the most critical factor influencing the wear rate of fabricated hybrid composites followed by sliding distance. Further, the AZ91D/5SiC/5Gr hybrid composite has exhibited the best wear properties. From the SEM and EDS analysis of worn surfaces, delamination was confirmed as the dominant wear mechanism for AZ91D-SiC-Gr hybrid composites.

Optimization and Effect of Reinforcements on the Sliding Wear Behavior of Self-Lubricating AZ91D-SiC-Gr Hybrid Composites

Dry sliding tribological behavior of AZ31-WC nano-composites

Corrosion behavior of AZ31-WC nano-composites

Abrasive wear behavior of WC nanoparticle reinforced magnesium metal matrix composites

Current study investigates the effect of graphite nanoparticles on nanoindentation behavior and corrosion characteristics of Mg–WC nanocomposites. Composites are developed by ultrasonic treatment associated stir casting method. Typical characterizations of nanocomposites are conducted using optical microscopy and scanning electron microscopy. Compositions of as cast materials are examined using energy dispersive X-ray analysis. Nanoindentation tests are conducted to expose elastic modulus and nanohardness of developed hybrid nanocomposites. Addition of 1 wt% nano Gr as reinforcement in Mg–WC has enhanced both nanohardness and elastic modulus of composites, while further addition include detrimental effects. Corrosion tests are performed with the help of electrochemical impedance spectroscopy and potentiodynamic polarization tests. Corrosion study reveals that incorporation of 1 wt% Gr has improved corrosion resistance but further addition of graphite nanoparticles results in decrease in the corrosion resistance. To ascertain corrosion mechanism, corroded surfaces are characterized which discloses that surface of Mg–2WC–1Gr nanocomposite possess less number of cracks collinear with its least corrosion rate among all hybrid nanocomposites.

Sudip Banerjee

Papers

Dry sliding tribological behavior of AZ31-WC nano-composites

Corrosion behavior of AZ31-WC nano-composites

Abrasive wear behavior of WC nanoparticle reinforced magnesium metal matrix composites

Nano-indentation and Corrosion Characteristics of Ultrasonic Vibration Assisted Stir-Cast AZ31–WC–Graphite Nano-composites

Tribological behavior of Mg-WC nano-composites at elevated temperature