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<p>Ceramic matrix composites (CMCs) face persistent challenges related to wear reliability and crack sensitivity in advanced applications. This study investigates Al<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub>–TiO<i>ₓ</i> composites fabricated using powder metallurgy, with alumina (Al<sub>2</sub>O<sub>3</sub>) fixed at 75 wt.%, zirconia (ZrO<sub>2</sub>) varied from 20&#xa0;to 10 wt.%, and titanium oxide (TiO<i>ₓ</i>) varied from 5&#xa0;to 15 wt.%. The powders were homogenized through high-energy ball milling and subsequently sintered at 1640 °C to achieve densification. Microstructural analysis (SEM and XRD) confirmed the formation of fine particles with stable crystalline phases. Tribological tests revealed composition-dependent behavior. A&#xa0;75:20:5 wt.% composite exhibited excellent wear resistance, with wear stabilizing at 1.8–2.1 µm, a&#xa0;friction coefficient of 0.7, and a&#xa0;friction force of 6 kN. This performance was attributed to tribo-layer formation, ZrO<sub>2</sub> phase transformation, and the lubricating effect of TiO<sub>x</sub>. A&#xa0;75:15:10 wt.% composite demonstrated moderate wear (4–5 µm), with a&#xa0;stable but higher friction coefficient (0.8–0.9) and a&#xa0;friction force of 4–8 kN, reflecting strong surface grip. In contrast, a&#xa0;75:10:15 wt.% composite stabilized at 4–4.5 µm wear, with a&#xa0;friction coefficient of 0.75 and a&#xa0;friction force of 4–4.5 kN, indicating variable sliding resistance but improved tribo-layer stability. Additionally, maintaining a&#xa0;specimen height-to-diameter (H/D) ratio of 3–4 minimized geometric errors, reduced crack initiation, and ensured reliable mechanical characterization. Inappropriate ratios, however, resulted in constraint effects, buckling, and edge cracking during cooling. Overall, the addition of TiOₓ to Al<sub>2</sub>O<sub>3</sub>–ZrO<sub>2</sub> composites improved the phase stability, crack resistance, and wear performance. Among the tested compositions, a&#xa0;75:20:5 wt.% composite demonstrated the most balanced properties, making it a&#xa0;promising candidate for high-durability structural, high-temperature, crucible, and biomedical applications.</p>

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Influence of titanium oxide (TiOx) reinforcement and ZrO2 modification on the wear behavior of alumina-based ceramic matrix composites

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • Donnapugari Raju,
  • M. Chandra Sekhara Reddy

摘要

Ceramic matrix composites (CMCs) face persistent challenges related to wear reliability and crack sensitivity in advanced applications. This study investigates Al2O3–ZrO2–TiOₓ composites fabricated using powder metallurgy, with alumina (Al2O3) fixed at 75 wt.%, zirconia (ZrO2) varied from 20 to 10 wt.%, and titanium oxide (TiOₓ) varied from 5 to 15 wt.%. The powders were homogenized through high-energy ball milling and subsequently sintered at 1640 °C to achieve densification. Microstructural analysis (SEM and XRD) confirmed the formation of fine particles with stable crystalline phases. Tribological tests revealed composition-dependent behavior. A 75:20:5 wt.% composite exhibited excellent wear resistance, with wear stabilizing at 1.8–2.1 µm, a friction coefficient of 0.7, and a friction force of 6 kN. This performance was attributed to tribo-layer formation, ZrO2 phase transformation, and the lubricating effect of TiOx. A 75:15:10 wt.% composite demonstrated moderate wear (4–5 µm), with a stable but higher friction coefficient (0.8–0.9) and a friction force of 4–8 kN, reflecting strong surface grip. In contrast, a 75:10:15 wt.% composite stabilized at 4–4.5 µm wear, with a friction coefficient of 0.75 and a friction force of 4–4.5 kN, indicating variable sliding resistance but improved tribo-layer stability. Additionally, maintaining a specimen height-to-diameter (H/D) ratio of 3–4 minimized geometric errors, reduced crack initiation, and ensured reliable mechanical characterization. Inappropriate ratios, however, resulted in constraint effects, buckling, and edge cracking during cooling. Overall, the addition of TiOₓ to Al2O3–ZrO2 composites improved the phase stability, crack resistance, and wear performance. Among the tested compositions, a 75:20:5 wt.% composite demonstrated the most balanced properties, making it a promising candidate for high-durability structural, high-temperature, crucible, and biomedical applications.