Printing Direction Effects on the Sliding Contact Response of a Binder Jetting 3D-Printed WC-Co Hardmetal

Abstract

Binder jetting additive manufacturing offers a promising route to produce complex geometries in cemented carbides (WC-Co), but it may introduce direction-dependent microstructural variations potentially affecting wear resistance. This study investigates the influence of printing direction on the sliding contact response of 3D-printed and subsequently sintered (BJT) WC-12%Co. Prismatic specimens were printed along two orientations and subjected to single and repetitive scratch tests on three orthogonal faces. The microstructure, Vickers and scratch hardness, and wear rate were analyzed. The results showed a heterogeneous microstructure consisting of a matrix of fine carbides where several large particles where embedded. It was different from the homogenous microstructural scenarios exhibited by conventionally pressed and sintered fine- and coarse-grained hardmetals, used as reference for comparison purposes. The influence of printing direction on either the microstructure or mechanical properties of BJT specimens was found to be negligible. Interestingly, BJT samples exhibited superior wear resistance than the reference hardmetals, even though the hardness levels were alike for all the studied hardmetal grades. Such behavior is attributed to the co-existence of coarse and fine carbides within the microstructure, combining the energy absorption capability of the former with the inherent strength of the latter. These findings, together with the intrinsic flexibility and versatility advantages associated with additive manufacturing, highlight the potential of BJT hardmetals to be used in applications where contact load bearing or wear resistance are critical design parameters. Finally, the effectiveness of implementing an iterative sliding contact test for evaluating wear behavior in cemented carbides was also validated.

Keywords

• binder jetting additive manufacturing
• WC-Co hardmetals
• scratch and wear testing
• deformation/damage/wear micromechanisms
• tribo-layer