3D-Printed Interpenetrating Ceramic–Metal Composites for Tribological Applications: Design, Fabrication, and Wear Mechanisms

Additive manufacturing enables ceramic–metal interpenetrating phase composites (IPCs) with designed load paths, but their tribological performance is constrained by coupled infiltration, interfacial damage, and lubrication processes. This review critically evaluates these constraints through an architecture–infiltration–interface–performance framework. Unlike conventional particle-reinforced metal matrix composites, IPCs require both phases to form three-dimensionally continuous networks; successful infiltration additionally requires preservation of the ceramic skeleton, adequate filling of the intended metal channels, and interfaces capable of transferring load. The central mechanical trade-off is between ceramic load support and accommodation of incompatible phase deformation. Thermal-expansion mismatch (Δα) generates residual stresses during post-infiltration cooling, while cyclic frictional heating superimposes spatially nonuniform thermal stresses that can promote interfacial microcracking and delamination. Increasing ceramic content or refining load paths must therefore be assessed against the remaining metal-ligament capacity for plastic accommodation and crack bridging, rather than hardness alone. Lubrication introduces a second trade-off: sufficient lubricant delivery can shift sliding from direct asperity contact toward tribofilm-mediated shear, whereas excessive lubricant content or reservoir porosity can weaken structural continuity and increase wear despite low friction. Sustained protection requires lubricant supply and film formation to offset depletion and removal. Current evidence does not establish universal optimal phase fractions or topology rankings, because direct, matched tribological studies of printed and subsequently infiltrated IPCs remain scarce. Quantitative design therefore requires joint characterization of phase connectivity, infiltration defects, residual and cyclic thermal stresses, interfacial fracture resistance, and tribofilm persistence under specified contact conditions.