Quantitative Kinematics of Thermal Transients in Thin-Layer PEEK/CF30 Composite and Implications for Temperature Monitoring of Plain Bearings

Thermal kinematics in two-layer systems, analogous to those employed in plain bearings, are investigated. The systems are based on a PEEK/CF30 composite, considered an established alternative to traditional babbitt alloys. Experimental modelling of transient and quasi-steady-state heat transfer regimes was performed on a test bench implementing a one-dimensional heat conduction model within multi-layered media. Samples included babbitt alloy and polymer coatings with thicknesses of 0.40, 0.46, and 1.92 mm. A phenomenological model of heat transfer regimes is proposed, encompassing five sequential phases that represent a complete operating cycle of plain bearing temperature traces. The observed constants of temperature deviations and phase lags are discussed, including their application as instrumental invariants. It was established that reducing the antifriction layer thickness to 0.4 mm significantly lowers its thermal resistance and decreases the time lag by a factor of 5–8. This brings the system response time close to values characteristic of classical babbitt alloys. It is demonstrated that in steady-state hydrodynamic friction regimes, the temperature deviation for thin layers is less than 1 °C, obviating the necessity for algorithmic data compensation. The findings confirm the safety of using polymer materials as the working layer in plain bearings. Despite their lower thermal conductivity and increased time lag, the composites’ high thermal stability margin comfortably compensates for potential temperature deviations, ensuring equipment reliability and safety.