Faculty Publications

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Author: search.filters.author.Harursampath, D.Subject: search.filters.subject.Aluminum graphite composites

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    Tribological performance and 3-D surface characterisation of age-hardened Al2090-based ceramic composites
    (SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.
    This study investigates the synergistic influence of boron nitride (BN) tertiary ceramic additives and age-hardening treatment on the microhardness and wear resistance of Al2090-based hybrid composites, fabricated using the stir casting method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies are carried out to assess the phases present, microstructure, and surface properties, respectively. The metallurgical investigations confirm a relatively superior uniformity in the distribution of particles and the ageing of precipitation at 150°C, vis-à-vis the other temperatures explored in this study. The experimental examinations conducted as per ASTM (E8 and G99) standards revealed a significant improvement in both the hardness and the primary tribological properties, when micron-sized boron carbide, graphite, and boron nitride were used as reinforcements. Age-hardened samples, especially the hybrid composite HS-2 with 5 wt.% each of boron carbide, graphite, and boron nitride, demonstrated an enhanced hardness of 25.23% and lower surface roughness (44.3 nm) compared to Al2090 (AS), due to the presence of load-bearing ceramic reinforcements. Increasing the applied load led to higher wear rates and coefficients of friction for Al2090. However, heat-treated hybrid metal matrix composites (HMMCs) exhibited a contrary behaviour, suggesting enhanced durability. The investigation highlighted the better wear resistance of heat-treated and near-optimally reinforced HMMCs, indicating their potential candidature for wear-resistant aerospace applications. © IMechE 2025.
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    On enhancing the high-temperature wear behaviour of Al2090-based hybrid composites using tertiary ceramic particles
    (SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.
    This study explores the impact of reinforcing an Al2090 matrix with silicon nitride (Si3N4) as a tertiary ceramic alongside boron carbide (B4C) and graphite (Gr) to improve wear resistance at elevated temperatures. Hybrid composite samples were produced using the stir-casting technique. Experimental results show that incorporating Si3N4increased hardness by 35.7%, while wear resistance improved by 43.7% with a combined reinforcement of B4C, Gr, and Si3N4at 18 wt.%. Scanning electron microscopy (SEM) revealed the formation of a mechanically mixed layer (MML) composed of B4C, Gr, and Si3N4, which acted as an effective insulating barrier, protecting the sample surface from the steel disc. A noteworthy 69% of wear resistance improvement was accomplished at 300 °C for the composite with 9 wt.% B4C, 6 wt.% Gr, and 3 wt.% Si3N4. Atomic force microscopy (AFM) analysis further indicated enhanced surface properties for this composition. These findings highlight the potential of this hybrid composite for high-temperature aerospace applications, such as in engines, heat shields, and structural components. © IMechE 2024