Enhanced Mechanical Performance of Polycrystalline Diamond Compacts Through Microstructural Modification with a Carbon–Hydrogen‐Based Quenching Fluid and Mechanistic Insights

Quenching liquids are widely used to control microstructures and improve material performance. Recent studies suggest that tuning the quenching‐medium cooling rate can optimize polycrystalline diamond compact (PDC) microstructural evolution. Although most research links PDC microstructure to thermal stability and tribological performance, the relationships among cooling rate, microstructure, and critical properties such as impact toughness and shear strength remain underexplored. How the cooling rate specifically controls PDC microstructural evolution to enhance performance remains unclear. his study systematically investigates the effect of cooling rate after high‐temperature treatment on PDC microstructure and performance. The slower cooling rate preserves diamond–diamond bonding, inhibits graphitization, and promotes a more uniform cobalt distribution along diamond grain boundaries. Nanohardness increases from 76 to 85 GPa; interfacial shear strength increases from 985 to 1009 MPa; wear resistance improves by approximately 33%; and impact resistance also increases. These findings indicate that a slower cooling rate in a carbon–hydrogen‐based quenching fluid facilitates microstructural refinement, which underpins the enhanced performance of PDC. This research provides a practical route to improving PDC performance and fundamental insights for optimizing PDC through thermal processing.