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<p>This study presents a comparative tribological evaluation of A356-15 wt. % SiC<sub>p</sub> functionally graded composites (FGCs) under unidirectional and reciprocating sliding at ambient (31&#xa0;°C) and elevated (350&#xa0;°C) temperatures. Tests were conducted at 1&#xa0;m/s under 15–45 N loads over a 350&#xa0;m sliding distance. FGCs were produced by vertical centrifugal casting using 30&#xa0;µm SiC<sub>p</sub>, generating a compositional gradient comprising chilled, particle-rich, transition, matrix-rich and porous zones. Microstructural examination and hardness profiling confirmed maximum hardness in the particle-rich region, and microstructure-hardness correlations were established for as-cast and T6-treated samples. Tribological behavior was assessed using a pin-on-disc and a patented pin-on-reciprocating plate setup with particle-rich (PRP) and matrix-rich (MRP) pins. At 31&#xa0;°C, reciprocating sliding resulted in higher wear than unidirectional sliding, with MRP showing greater wear than PRP. At 350&#xa0;°C, MRP exhibited an early mild-to-severe wear transition above a critical load of 30 N under reciprocating contact, while unidirectional sliding showed a gradual wear increase with load. The coefficient of friction was lower in reciprocating sliding and decreased with load, whereas unidirectional sliding showed an opposite trend. SEM and EDS analyses revealed distinct wear mechanisms: MRP displayed severe ploughing, tearing and oxygen/iron-rich oxidative wear at elevated temperature under reciprocating contact, while PRP showed abrasion and improved glaze-layer stability. Wear debris morphology confirmed delamination wear in unidirectional sliding and transition wear under reciprocating conditions. Overall, the study demonstrates the influence of microstructural gradients and sliding mode on wear behavior, highlighting tribological performance of particle-rich regions in SiC<sub>p</sub>-reinforced FGCs.</p>

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A Comparative Study of the Elevated Temperature Wear Characteristics of A356-15wt. % SiCp Functionally Graded Composite Under Unidirectional and Reciprocating Sliding Contacts

  • 期刊论文

  • 发表日期：

    2026年3月20日

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  • T. C. Jibin Bose,
  • V. R. Rajeev,
  • M. Hashim,
  • J. Prem Kumar

摘要

This study presents a comparative tribological evaluation of A356-15 wt. % SiCp functionally graded composites (FGCs) under unidirectional and reciprocating sliding at ambient (31 °C) and elevated (350 °C) temperatures. Tests were conducted at 1 m/s under 15–45 N loads over a 350 m sliding distance. FGCs were produced by vertical centrifugal casting using 30 µm SiCp, generating a compositional gradient comprising chilled, particle-rich, transition, matrix-rich and porous zones. Microstructural examination and hardness profiling confirmed maximum hardness in the particle-rich region, and microstructure-hardness correlations were established for as-cast and T6-treated samples. Tribological behavior was assessed using a pin-on-disc and a patented pin-on-reciprocating plate setup with particle-rich (PRP) and matrix-rich (MRP) pins. At 31 °C, reciprocating sliding resulted in higher wear than unidirectional sliding, with MRP showing greater wear than PRP. At 350 °C, MRP exhibited an early mild-to-severe wear transition above a critical load of 30 N under reciprocating contact, while unidirectional sliding showed a gradual wear increase with load. The coefficient of friction was lower in reciprocating sliding and decreased with load, whereas unidirectional sliding showed an opposite trend. SEM and EDS analyses revealed distinct wear mechanisms: MRP displayed severe ploughing, tearing and oxygen/iron-rich oxidative wear at elevated temperature under reciprocating contact, while PRP showed abrasion and improved glaze-layer stability. Wear debris morphology confirmed delamination wear in unidirectional sliding and transition wear under reciprocating conditions. Overall, the study demonstrates the influence of microstructural gradients and sliding mode on wear behavior, highlighting tribological performance of particle-rich regions in SiCp-reinforced FGCs.