Effect of substrate temperature on LIBS characteristic spectral signals in laser paint stripping of aluminum alloys

Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the online monitoring of laser paint stripping. This study investigates how substrate preheating (50°C-300°C) affects the ablation behavior and spectral response of coatings on the 2024-T3 aluminum alloy. Increasing the substrate temperature reduces the coating ablation threshold and enhances Ti emission intensity, improving the stripping efficiency up to 250°C, above which self-absorption weakens the signal. Increased Mg and Fe emissions indicate earlier substrate exposure during stripping. An optimal substrate temperature window of 100°C-150°C balances LIBS signal intensity and stability, thereby supporting process monitoring and optimization.