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In this study, graphite/CeO 2 reinforced Co-based coatings were prepared on the surface of HT250 gray cast iron by the plasma cladding technology. The influence of graphite and CeO 2 on microstructure and properties of Co-based coatings were studied in detail. The phase composition and microstructure of coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The micro-hardness, wear resistance and corrosion resistance of coatings were evaluated using micro-hardness tester, friction wear testing machine and electrochemical workstation. The results showed that the addition of graphite was beneficial to enhance micro-hardness and wear resistance of coatings, but there was still shortcoming in improving corrosion resistance. On this basis, CeO 2 was further introduced together with graphite. The microstructure of coatings was found to be more uniform under the synergy of graphite and CeO 2. The micro-hardness increased from 684.5 HV 0.3 (coatings adding graphite alone) to 767.4 HV 0.3 (coatings adding graphite and CeO 2), which was 29.7% and 115.1% higher than that of as-cladded coatings and substrate respectively. More importantly, the corrosion current density of coatings was an order of magnitude lower than that of coatings adding graphite alone. Therefore, adding CeO 2 together with graphite was beneficial to the synergistic improvement of micro-hardness, wear resistance and corrosion resistance of Co-based coatings. • Co-based coatings adding graphite/CeO 2 were prepared by plasma cladding. • The microstructure of coatings became uniform after adding graphite/CeO 2. • Wear resistance of coatings adding graphite together with CeO 2 was enhanced. • Corrosion resistance of coatings adding graphite together with CeO 2 was raised. [ABSTRACT FROM AUTHOR]

We investigate herein that whether the directional array TiN can improve the wear resistance of AlCoCrFeNiTi high-entropy alloy (HEA) coating. The results show that the microstructures of in-situ TiN display a "cross" shape of the directional array, and a coherent interface in TiN (2 0 0)/(Ni, Co)Ti 2 (5 1 1) and the high bonding strength between TiN and BCC improve the wear resistance of HEA coating. [Display omitted] • The directional array TiN is synthesized in high entropy alloy coating. • The coherent interface optimizes the interface stability of TiN/(Ni, Co)Ti 2. • The high bonding strength improves the wear resistance of high entropy alloy coating. Recent studies have shown that ceramic particles reinforced high entropy alloy (HEA) has attracted increased attention due to their excellent strength and wear resistance. In this work, the directional array TiN-reinforced AlCoCrFeNiTi HEA coating was synthesized via magnetic field-assisted laser cladding. Besides, the wear resistance of HEA coating was systematically investigated. The atomic structure, ideal adhesion work (W ad) and electronic structure of the interface between matrix and TiN were calculated by first principles method. The results show that the microstructures of in-situ TiN display a "cross" shape of the directional array, and a coherent interface in TiN (2 0 0)/(Ni, Co)Ti 2 (5 1 1) and the high bonding strength between TiN and BCC improve the wear resistance of HEA coating. [ABSTRACT FROM AUTHOR]

In this work, the YSZ fibers and multi-walled carbon nanotubes (MWCNTs) were respectively employed as the extra additive to make some effect to improve the mechanical and thermal properties of YSZ-La 2 Zr 2 O 7 double-layer (LZ) thermal barrier coatings (TBCs). The porosity, thermal conductivity, bonding strength, fracture toughness and thermal cycling behavior of coatings were tested and discussed. The results showed that the addition of YSZ fibers and MWCNTs could improve the properties of LZ coating. In particular, the LZ coating exhibited lower thermal conductivity than that of YSZ coating with single-layer. Compared with MWCNTs reinforced LZ coating, YSZ fibers reinforced coating showed the lowest thermal conductivity and highest bonding strength value, due to the outstanding reinforcement of fibers. In contrast, the LZ coating containing MWCNTs presented the highest fracture toughness value and the best thermal cycling behavior than those of LZ coating and LZ coating containing YSZ fibers, which were attributed to the lowest porosity existing in LZ coating with MWCNTs, contributing to the remarkable inhibition of crack propagation. Therefore, the addition of YSZ fibers and MWCNTs was expected to be a potential way to improve the mechanical and thermal properties of LZ-TBCs. • Comparison study of adding YSZ fibers or MWCNTs in YSZ-La 2 Zr 2 O 7 TBCs was explored. • Adding YSZ fiber or MWCNTs can increase or decrease porosity of TBCs, respectively. • MWCNTs improved the fracture toughness of coatings better than YSZ fibers. • Coatings adding YSZ fibers present the highest bonding strength. • The MWCNTs-containing coatings possess the best thermal cycling lifetime. [ABSTRACT FROM AUTHOR]

The improvement of wear resistance has a profound effect on the far-ranging application of aluminum alloy. In this study, the Al–Cu-based in-situ reinforced composite coating was successfully manufactured on the AlSi10Mg substrate by laser cladding. The microstructure, microhardness and wear resistance under gradient loading (3 N, 6 N, 9 N, 12 N and 15 N) and thermal conditions (200 °C, 300 °C and 400 °C) of the composite coating were studied. The research results showed that the composite coating exhibited a gradient distributed microstructure due to the different diffusion degrees of Cu and Al atoms. The composite coating was mainly composed of Al 4 Cu 9 , Al 7 Cu 4 Ni and α-Al in the bottom, center and top area, respectively, and Al 2 Cu evenly distributed in each area. The microhardness showed gradient distribution owing to the gradient microstructure. Compared with the AlSi10Mg substrate, the composite coating possessed higher microhardness and better wear resistance contributed by the gradient Al–Cu intermetallic compounds. At room temperature, the main wear mechanisms of the composite coating changed from abrasive wear to adhesive wear with the increase of loading condition. At high temperatures, the main wear mechanisms of the composite coating were adhesive wear and plastic flow. During the wear process, Al–Cu intermetallic compound was the key to improving the wear resistance and stabilizing the friction coefficient. • The Al–Cu-based composite coating with gradient distribution on Al alloy was prepared. • The diffusion properties of Al and Cu elements were briefly analyzed. • The friction property of the coating is improved than the substrate at room and high temperatures. • The increase of Al–Cu intermetallic and the transformation of microstructure make the coating have better properties. [ABSTRACT FROM AUTHOR]

FeCoCrNiCu is a face-centered cubic (FCC) high entropy alloy (HEA) with good dislocation storage capacity, ductility, and toughness. FeCoCrNiAl is a body-centered cubic (BCC) HEA whose phase is hard and brittle with high strength and low toughness. In this study, a FeCoCrNiCu/FeCoCrNiAl composite HEA coating was prepared by laser cladding technology. After preparation, the microstructure and mechanical properties of the composite HEA were evaluated. A new two-phase (FCC + BCC) HEA was generated in situ between FCC and BCC HEA, achieving a good transition from hard to soft. The composite coating has the best wear resistance, the friction coefficient is about 0.3, the wear rate is 4.2 × 10−5 mm3/ N·m, and the wear mechanism is abrasive wear. While maintaining high hardness and good wear resistance, the composite coating has good compression properties. The FeCoCrNiCu cladding layer reduced the energy of the FeCoCrNiAl cladding layer by storing dislocations, which reduced its tendency to crack during compression, thus extending the service life of the coating surface. • FeCoCrNiCu/FeCoCrNiAlCu/FeCoCrNiAl composite high entropy alloy coating was successfully prepared by laser cladding. • In-situ generation of FeCoCrNiAlCu dual-phase high-entropy alloy. • Gradient distribution of coating hardness. • The composite HEA coating achieved an effective strength-toughness balance. [ABSTRACT FROM AUTHOR]

Background & Aims: Intestinal fibrosis is a significant complication of Crohn's disease (CD). Gut microbiota reactive Th17 cells are crucial in the pathogenesis of CD; however, how Th17 cells induce intestinal fibrosis is still not completely understood., Methods: In this study, T-cell transfer model with wild-type (WT) and Areg -/- Th17 cells and dextran sulfate sodium (DSS)-induced chronic colitis model in WT and Areg -/- mice were used. CD4 + T-cell expression of AREG was determined by quantitative reverse-transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. The effect of AREG on proliferation/migration/collagen expression in human intestinal myofibroblasts was determined. AREG expression was assessed in healthy controls and patients with CD with or without intestinal fibrosis., Results: Although Th1 and Th17 cells induced intestinal inflammation at similar levels when transferred into Tcrβxδ -/- mice, Th17 cells induced more severe intestinal fibrosis. Th17 cells expressed higher levels of AREG than Th1 cells. Areg -/- mice developed less severe intestinal fibrosis compared with WT mice on DSS insults. Transfer of Areg -/- Th17 cells induced less severe fibrosis in Tcrβxδ -/- mice compared with WT Th17 cells. Interleukin (IL)6 and IL21 promoted AREG expression in Th17 cells by activating Stat3. Stat3 inhibitor suppressed Th17-induced intestinal fibrosis. AREG promoted human intestinal myofibroblast proliferation, motility, and collagen I expression, which was mediated by activating mammalian target of rapamycin and MEK. AREG expression was increased in intestinal CD4 + T cells in fibrotic sites compared with nonfibrotic sites from patients with CD., Conclusions: These findings reveal that Th17-derived AREG promotes intestinal fibrotic responses in experimental colitis and human patients with CD. Thereby, AREG might serve as a potential therapeutic target for fibrosis in CD., (Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background: Intestinal immune dysfunction is involved in the onset of Crohn's disease (CD). Dendritic cells (DCs), antigen-presenting cells, play a key role in the maintenance of intestinal immune homeostasis. The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor widely expressed in various immune cells, including DCs. Although AhR plays an important role in immune tolerance, its role in the DCs is unclear. The purpose of this study was to investigate whether the activation of AhR can induce tolerogenic DCs (tolDCs) and the differentiation of regulatory T (Treg) cells, as well as ameliorate experimental colitis., Results: AhR activation in the DCs resulted in a lower expression of surface markers such as CD80, CD83, CD86, and pro-inflammatory cytokine production, and higher anti-inflammatory production (IL-1β, IL-23, and IL-12) compared to the control DCs. The surface dendrites in DCs were significantly reduced following AhR activation by 6-formylindolo [3,2-b]carbazole (FICZ). Such DCs with FICZ-mediated activation of AhR, namely tolDCs, promoted Treg cell differentiation. Adoptive transfer of tolDCs to a TNBS-induced colitis mouse model significantly alleviated the severity of inflammation by improving the colon length and decreasing the disease activity index (DAI) and histopathological score. Moreover, the transferred tolDCs decreased the frequency of Th17 cells and increased the frequency of Treg cells in the spleen and mesenteric lymph nodes (MLNs) in murine colitis models., Conclusions: Activation of AhR in the DCs could induce tolDCs, and the transplantation of tolDCs may help in relieving intestinal inflammation and maintaining the Th17/Treg differentiation balance. Thus, our data suggest that AhR may be a potential therapeutic target for CD., (© 2022. The Author(s).)