Thermal expansion of the titanium carbonitride system by molecular dynamics simulations and X-ray diffraction

The TiC x N 1 − x ( 0 ≤ x ≤ 1 ) is widely used in wear-resistant and high-temperature coatings, where a precise understanding of its thermal expansion behavior is essential to prevent delamination, cracking, and thermal fatigue during service. Although several studies have examined its thermal expansion, reported values vary significantly depending on measurement conditions and composition. This work integrates high-temperature X-ray diffraction (HT-XRD) experiments and molecular dynamics (MD) simulations to determine the thermal expansion of TiC x N 1 − x between 300 and 2500 K. The lattice parameter was fitted as a function of temperature using linear and quadratic polynomials to extract reliable thermal expansion coefficients. The MD-derived linear thermal expansion coefficients agree within 3% of experimental trends, confirming the accuracy of the simulations for predicting first-order thermal behavior. While second-order terms deviated by up to 59%, their contribution to the overall expansion was negligible. Simplified linear expressions for the lattice parameter ( a ) and average thermal expansion coefficient ( α a v ) are thus reported as explicit functions of temperature and composition. These results provide practical equations for the design and thermal matching of TiC x N 1 − x coatings with metallic or ceramic substrates, enabling improved durability in cutting tools, thermal barrier coatings, and other high-temperature mechanical applications. The combined experimental–computational approach demonstrates a rapid and transferable methodology for optimizing thermomechanical performance in advanced nitride–carbide materials and TiC x N ( 1 − x ) coated diamond tools. • Simulations of the thermal expansion of titanium carbonitrides within a 3% literature difference. • Measurement of the thermal expansion by X-ray diffraction within an 8% literature difference. • Results show that the linear fitting is sufficient to calculate the thermal expansion. • Found an equation for the lattice parameter depending on temperature and composition. • Findings guide design of novel diamond-based anti-wear coatings.