RESIDUAL STRESS AND FRACTURE TOUGHNESS OF PIRAC TITANIUM NITRIDE COATINGS
Abstract
In this work, residual stress and fracture toughness of titanium nitride coatings prepared by powder immersion reaction assisted coating (PIRAC) at 700∘C with different processing times are studied. Results show that the residual stress in the coatings is compressive stress and increases with processing times increasing. Indentation fracture toughness of the PIRAC coatings increased with processing times (coatings’ thickness) increasing. The fracture toughness of the coatings prepared at 700∘C with a processing time of 144h and 192h is 6.88±0.20MPa⋅m1∕2 and 9.15±0.15MPa⋅ m1∕2, respectively. Bending induced crack propagation in the coating shows multi-deflection mode which is beneficial to energy absorption and thus improved fracture toughness.
