Use of spark plasma sintering for the production of high-performance coatings: Titanium carbide–iron composite

Abstract

Spark plasma sintering was employed to fabricate dense titanium carbide–iron composite coatings on tungsten carbide-cobalt (8 wt.% cobalt) substrates. The choice of titanium carbide–iron was motivated by its high hardness, good thermal-shock resistance, lower density compared with tungsten carbide–cobalt, and the avoidance of cobalt-related health concerns, making it a promising candidate for cutting and forming tools. Powder mixtures containing different iron fractions (10, 20, and 30 wt%) were consolidated at 1500 °C. Phase composition was identified by X-ray diffraction, and microstructure was examined by field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The influence of iron content on densification, microstructural development, mechanical integrity, and wear performance was systematically evaluated. Bonding strength decreased with lower iron due to reduced plastic accommodation, while hardness increased from ∼11 to ∼15 GPa with decreasing iron. Tribological tests showed that reducing iron content markedly decreased the coefficient of friction (from ∼0.68 to ∼0.41) and wear rate (from 3.2 × 10⁻⁴ to 5.6 × 10⁻⁶ mm³/N·m). Microscopy of worn surfaces indicated a transition from delamination-dominated wear in iron-rich coatings to oxidation-assisted protective tribofilm formation in titanium carbice-rich coatings. These findings highlight that the interplay between densification, microstructure, and microscopic defects governs both mechanical integrity and wear performance.