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<p>This study investigates the microstructural evolution, high-temperature tribological behavior, and corrosion performance of titanium–vanadium carbide (TiVC) composite coatings produced by thermo-reactive diffusion (TRD) on vermicular graphite cast iron (CGI) substrates at 800-1000&#xa0;°C. Coatings were characterized using SEM, EDS, XRD, surface profilometry, microhardness, wear tests at room temperature and 500&#xa0;°C, and electrochemical corrosion analyses. Results indicate that TRD temperature strongly influences phase composition, morphology, and functional properties. At 800&#xa0;°C, vanadium carbide (VC) was predominantly formed, whereas increasing temperature promoted titanium carbide (TiC) formation due to titanium’s higher carbon affinity. Coating thickness ranged from 7.5 ± 0.3&#xa0;µm to 17.5 ± 2.1&#xa0;µm, with microhardness values between 2600 and 3500&#xa0;HV 0.025. Compared to untreated CGI (COF ≈ 0.45-0.52), TiVC coatings significantly reduced and stabilized friction. The coating produced at 900&#xa0;°C showed the most stable performance (COF 0.20-0.25), attributed to its dense and homogeneous microstructure. Wear resistance improved markedly at both test temperatures, consistent with Archard’s law. However, coatings formed at 1000&#xa0;°C exhibited severe layer delamination during 500&#xa0;°C wear tests due to thermal expansion mismatch. Corrosion analyses revealed that the 800&#xa0;°C coating, dominated by the VC phase, provided the highest corrosion resistance, lowering the corrosion rate by approximately fivefold. In contrast, coatings produced at 1000&#xa0;°C showed increased galvanic corrosion susceptibility, associated with grain coarsening and microcrack formation. Overall, TiVC composite coatings fabricated by TRD demonstrate strong potential for enhancing the high-temperature wear and corrosion resistance of CGI components operating under severe tribo-corrosive conditions.</p>

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Effect of Process Temperature on Microstructure, High-Temperature Wear, and Corrosion Behavior of Titanium–Vanadium Carbide Composite Coatings Grown on Compacted Graphite Iron

  • 期刊论文

  • 发表日期：

    2026年5月19日

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  • Mehmet Demir

摘要

This study investigates the microstructural evolution, high-temperature tribological behavior, and corrosion performance of titanium–vanadium carbide (TiVC) composite coatings produced by thermo-reactive diffusion (TRD) on vermicular graphite cast iron (CGI) substrates at 800-1000 °C. Coatings were characterized using SEM, EDS, XRD, surface profilometry, microhardness, wear tests at room temperature and 500 °C, and electrochemical corrosion analyses. Results indicate that TRD temperature strongly influences phase composition, morphology, and functional properties. At 800 °C, vanadium carbide (VC) was predominantly formed, whereas increasing temperature promoted titanium carbide (TiC) formation due to titanium’s higher carbon affinity. Coating thickness ranged from 7.5 ± 0.3 µm to 17.5 ± 2.1 µm, with microhardness values between 2600 and 3500 HV 0.025. Compared to untreated CGI (COF ≈ 0.45-0.52), TiVC coatings significantly reduced and stabilized friction. The coating produced at 900 °C showed the most stable performance (COF 0.20-0.25), attributed to its dense and homogeneous microstructure. Wear resistance improved markedly at both test temperatures, consistent with Archard’s law. However, coatings formed at 1000 °C exhibited severe layer delamination during 500 °C wear tests due to thermal expansion mismatch. Corrosion analyses revealed that the 800 °C coating, dominated by the VC phase, provided the highest corrosion resistance, lowering the corrosion rate by approximately fivefold. In contrast, coatings produced at 1000 °C showed increased galvanic corrosion susceptibility, associated with grain coarsening and microcrack formation. Overall, TiVC composite coatings fabricated by TRD demonstrate strong potential for enhancing the high-temperature wear and corrosion resistance of CGI components operating under severe tribo-corrosive conditions.