Morphological and textural characteristics of tire-road wear particles linked to different wear mechanisms
Xuan-Trinh Truong, Bogdan Muresan, L. Lumière, Y. Liu, Véronique Cerezo
Abstract
Air quality is a critical public health and environmental issue, with transport-related particulate pollution causing over 350,000 premature deaths annually in the EU. Non-exhaust emissions like tire-road wear particles (TRWP) persist even with the advent of electric vehicles, posing characterization challenges due to their complex formation and lack of standardized analysis methods. TRWP result from friction and shear between tires tread and road surfaces, influenced by tread adhesion and road texture, and mix with debris under real conditions, acquiring complex properties. This study examined the link between tire-road interface stresses and TRWP characteristics using an instrumented vehicle with dynamometric wheels. An on-board system was designed to collect TRWP emissions and determine their mass-weighted size distribution. SEM-EDX analysis integrated physical (morphology and texture) and chemical (elemental composition) traits to identify both literature-documented and potential TRWP. This approach highlights wear mechanisms like abrasion, fatigue, and pull-out, advancing understanding of tribological processes driving TRWP emissions. The results show that TRWP are highly variable in terms of morphology, texture and elemental composition. This diversity is strongly influenced by driving conditions (e.g. sudden braking, overtaking), road characteristics (e.g. low or high speed circulation) and pavement condition (e.g. deterioration, road dust, infrastructure such as retarders). Fatigue often results in elongated TRWP, ranging in size from a few micrometers to over 50 μm, with a characteristic rough, jagged texture. These TRWP (500–1200 particles/circuit) are in line with those reported in the literature. In contrast, spherical or irregular forms with smoother surfaces (2700–3400 particles/circuit) result from repeated particle blending or tread tearing due to intense friction and shear forces. These particles, which are often smaller (down to around 0.2 μm on highway), are classified in the category partially conforming to the TRWP observed in the literature.