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<p>Hybrid composites are vital to advancements in modern material engineering, offering an optimal balance between performance, cost, and sustainability. This study investigates the development and characterization of Al7075-based hybrid composites reinforced with varying weight fractions of silicon nitride (Si<sub>3</sub>N<sub>4</sub>) and graphite (Gr) using a vacuum-sealed bottom-pouring stir-casting process. Four specimens were fabricated: the base Al7075 alloy and three hybrid composites containing 3.5&#xa0;wt.% Si<sub>3</sub>N<sub>4 </sub>+ 5.5&#xa0;wt.% Gr, 4.5&#xa0;wt.% Si<sub>3</sub>N<sub>4 </sub>+ 4.5&#xa0;wt.% Gr, and 5.5&#xa0;wt.% Si<sub>3</sub>N<sub>4 </sub>+ 3.5&#xa0;wt.% Gr. The physical (theoretical density, experimental density, and porosity) and tribological (wear loss, frictional loss, and coefficient of friction) properties were evaluated under dry sliding conditions at 35&#xa0;°C. The results revealed that the composite with 5.5&#xa0;wt.% Si<sub>3</sub>N<sub>4 </sub>+ 3.5&#xa0;wt.% Gr exhibited the best performance, showing modest increases in theoretical density (≈1.39%) and experimental density (≈1.76%) but significant reductions in porosity (≈50.70%), wear loss (≈48.95%), frictional loss (≈64.45%), and coefficient of friction (≈38.89%) compared to the as-cast Al7075 alloy. Furthermore, a microstructural, XRD, and SEM analyses confirmed uniform particle dispersion, phase identification, delamination, and adhesive–abrasive wear mechanisms. These findings demonstrate that Al7075–Si<sub>3</sub>N<sub>4</sub>Gr hybrid composites offer significant potential as lightweight, wear-resistant materials for automotive and aerospace components like brake rotors, pistons, connecting rods, gear housings, and structural panels.</p> Graphical Abstract <p></p>

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Experimental Assessment on Physical–Tribological Profiling of Transformative Hybrid Composite Encompassed with As-Cast Al-7075 + 5.5 Wt.% Si3N4 + 3.5 Wt.% Gr via Stir-Casting Route

  • 期刊论文

  • 发表日期：

    2025年11月29日

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  • Nikhilesh Singh,
  • Deepika

摘要

Hybrid composites are vital to advancements in modern material engineering, offering an optimal balance between performance, cost, and sustainability. This study investigates the development and characterization of Al7075-based hybrid composites reinforced with varying weight fractions of silicon nitride (Si3N4) and graphite (Gr) using a vacuum-sealed bottom-pouring stir-casting process. Four specimens were fabricated: the base Al7075 alloy and three hybrid composites containing 3.5 wt.% Si3N4 + 5.5 wt.% Gr, 4.5 wt.% Si3N4 + 4.5 wt.% Gr, and 5.5 wt.% Si3N4 + 3.5 wt.% Gr. The physical (theoretical density, experimental density, and porosity) and tribological (wear loss, frictional loss, and coefficient of friction) properties were evaluated under dry sliding conditions at 35 °C. The results revealed that the composite with 5.5 wt.% Si3N4 + 3.5 wt.% Gr exhibited the best performance, showing modest increases in theoretical density (≈1.39%) and experimental density (≈1.76%) but significant reductions in porosity (≈50.70%), wear loss (≈48.95%), frictional loss (≈64.45%), and coefficient of friction (≈38.89%) compared to the as-cast Al7075 alloy. Furthermore, a microstructural, XRD, and SEM analyses confirmed uniform particle dispersion, phase identification, delamination, and adhesive–abrasive wear mechanisms. These findings demonstrate that Al7075–Si3N4Gr hybrid composites offer significant potential as lightweight, wear-resistant materials for automotive and aerospace components like brake rotors, pistons, connecting rods, gear housings, and structural panels.

Graphical Abstract