Dalian Jiaotong University

Urban rail wheels endure prolonged exposure to frequent starts and stops, heavy cyclic loads, and complex track conditions, which often lead to premature failure modes such as wear, fatigue cracking, and corrosion in conventional wheel materials. These limitations restrict their ability to meet the evolving demands of modern rail systems for enhanced durability and performance. To address this, the present study uses laser cladding to deposit high-entropy alloy coatings with systematically varied aluminium content onto wheel substrates. The study compares phase composition, microstructure, and mechanical properties across the different coatings. Results show that increasing Al content transforms the coating microstructure from a single face-centred cubic (FCC) phase to a dual-phase structure of FCC and body-centred cubic (BCC) phases, accompanied by notable grain refinement. Among the variants, the CrMnFeCoNi(Al)8 coating has the densest microstructure and the most favourable mechanical performance. It achieves a microhardness of 399.62 HV0.5 in the as-clad state and 450 ± 5 HV0.5 after heat treatment, representing an increase of approximately 12.6%. This coating also demonstrates improved corrosion resistance, with an open-circuit potential 0.07 V higher than the CL60 substrate. Multi-body dynamics simulations confirm that the clad wheels maintain excellent operational stability and safety under service conditions.

ABSTRACT Nonaromatic organic small‐molecule luminescent materials have garnered significant attention in optoelectronic devices and biomedical applications due to their simple structures and excellent biocompatibility. However, steric hindrance and a large bandgap often constrain their efficient luminescence. Herein, we employ pressure treatment to induce highly efficient room‐temperature phosphorescence, achieving a significant emission enhancement in weakly emitting nonaromatic barbituric acid crystals. The absolute photoluminescence quantum yield of the treated samples increases from an initial 2.22% to 12.53% through 20.0 GPa pressure treatment by the Walker‐type large‐volume press. Additionally, after different pressure treatments, the emission changes from blue light with CIE coordinates (0.17, 0.10) to blue‐white light with CIE coordinates (0.23, 0.34). Detailed experimental and theoretical analyses reveal that pressure treatment selectively reconfigures the hydrogen‐bond network, generating free hydroxyl groups. The engineered electronic structure introduces new n‐π * transitions, which allow an intersystem crossing pathway from the 1 (n, π * ) state to the 3 (π, π * ) state, enabling efficient occupation of triplet excitons. This work provides novel insights and approaches for regulating exciton behavior through hydrogen bond engineering in nonaromatic organic systems, thereby facilitating the development of efficient luminescent materials.

Soft crawling robots have attracted substantial attention for their environmental adaptability and compliant locomotion. However, the scalability of many soft in-pipe robots to large diameters remains limited because their locomotion typically relies on multi-point contact with the pipe inner wall. To overcome this limitation, we propose SMART-PIPEBOT, a woodpecker-tail-inspired adhesion-driven soft pipeline climbing robot that achieves single-sidewall attachment and locomotion in large-diameter pipes while markedly reducing dependence on distributed wall support. SMART-PIPEBOT integrates an inflatable silicone bladder, vacuum sucker brackets, silicone vacuum suckers, a constraining layer, and an elastic tail-support frame. Experiments quantified how vacuum-sucker inclination (10°–50°) affects adhesion at 0.05 MPa and evaluated single-sidewall climbing performance in large-diameter pipes (170, 200, and 230 mm). The maximum mean adhesion force was 26.778 N at a 30° inclination. SMART-PIPEBOT achieves maximum climbing speeds of 16.93 mm/s horizontally and 12.63 mm/s vertically under dry conditions and maintains continuous locomotion on wet walls with mean speeds of 4 mm/s (23.6% of the dry horizontal) and 2 mm/s (15.7% of the dry vertical). Payload experiments further demonstrate a pronounced improvement in effective load capacity when inspection equipment is mounted at the rear rather than the front, enabling a twofold increase in horizontal payload (100 g vs. 50 g) and a 1.5× increase in vertical payload (30 g vs. 20 g).