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In order to improve the surface properties of hot work mold steel, the influence and mechanism of laser quenching, plasma nitriding and laser quenching/plasma nitriding composite treatment process on the friction, wear and corrosion resistance of the modified layer of H13 steel were studied. The surface morphology, surface chemical composition and microstructure of samples with different heat-treated were characterized by optical microscope, scanning electron microscope and energy dispersive spectrometer. Results showed that the composite treatment process could significantly improve the friction and wear resistance of the modified layer, and improve the corrosion resistance of the material surface. Compared with the single laser quenching and single nitriding treatment, the average friction coefficient of the modified layer after composite treatment declined significantly, the self-corrosion potential was remarkably increased, which indicated that the wear resistance and corrosion resistance of the modified layer after composite treatment were improved dramatically.

AISI 316L stainless steel has received considerable attention as a common material for key ball valve components; however, its properties cannot be improved through traditional phase transformation, and fretting wears the contact interface between valve parts. A carburized layer was prepared on the surface of AISI 316L stainless steel by using double-glow low-temperature plasma carburization technology. This study reveals the effect of double-glow low-temperature plasma carburization technology on the fretting wear mechanism of AISI 316L steel under different normal loads and displacements. The fretting wear behavior and energy dissipation of the AISI 316L steel and the carburized layer were studied on an SRV-V fretting friction and wear machine with ball–plane contact. The wear mark morphology was analyzed by using scanning electron microscopy (SEM), the phase structure of the carburized layer was characterized with X-ray diffractometry (XRD), and the wear profile and wear volume were evaluated with laser confocal microscopy. The carburized layer contains a single Sc phase, a uniform and dense structure, and a metallurgically combined matrix. After plasma carburizing, the sample exhibited a maximum surface hardness of 897 ± 18 HV0.2, which is approximately four times higher than that of the matrix (273 ± 33 HV0.2). Moreover, the surface roughness was approximately doubled. The wear depth, wear rate, and frictional dissipation energy coefficient of the carburized layer were significantly reduced by up to approximately an order of magnitude compared with the matrix, while the wear resistance and fretting wear stability of the carburized layer were significantly improved. Under different load conditions, the wear mechanism of the AISI 316L steel changed from adhesive wear and abrasive wear to adhesive wear, fatigue delamination, and abrasive wear. Meanwhile, the wear mechanism of the carburized layer changed from adhesive wear to adhesive wear and fatigue delamination, accompanied by a furrowing effect. Under variable displacement conditions, both the AISI 316L steel and carburized layer mainly exhibited adhesive wear and fatigue peeling. Oxygen elements accumulated in the wear marks of the AISI 316L steel and carburized layer, indicating oxidative wear. The fretting wear properties of the AISI 316L steel and carburized layer were determined using the coupled competition between mechanical factors and thermochemical factors. Low-temperature plasma carburization technology improved the stability of the fretting wear process and changed the fretting regime of the AISI 316L steel and could be considered as anti-wearing coatings of ball valves. [ABSTRACT FROM AUTHOR]

Introduction: Hilar cholangiocarcinoma (HC) is the leading cause of hilar biliary obstruction. Radioactive stent insertion has been utilized extensively for inoperable HC patients., Aim: To assess the relative clinical outcomes of inoperable HC patients who underwent either normal or radioactive stent insertion., Material and Methods: This single-center, prospective, randomized, open-label study enrolled 90 inoperable HC patients from April 2021 to March 2022 and randomly assigned them to normal or radioactive stent groups (n = 45/group), with clinical data then being compared between these groups., Results: Technical success rates in the normal and radioactive stent insertion groups were 93.3% and 97.9%, respectively (p = 1.000), and clinical success rates were similarly consistent in both groups (95.3% vs. 97.7%, p = 0.983). Individuals in the radioactive stent group exhibited significantly longer median stent patency as compared to the normal stent group (195 days vs. 115 days, p < 0.001), and median overall survival (OS) was also significantly increased in the normal stent group (242 days vs. 125 days, p = 0.002). In the normal stent insertion group, 6 (14.3%) and 5 (11.9%) patients experienced early and late postoperative complications, respectively. Additionally, early and late postoperative complications impacted 7 (16.3%) and 8 (18.6%) patients in the radioactive stent insertion group, respectively. Complication rates were comparable in these 2 patient groups., Conclusions: Radioactive stent insertion represents a safe and effective strategy for patients with inoperable HC, potentially contributing to prolonged stent patency and OS relative to normal stent insertion., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Sekcja Wideochirurgii TChP.)