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ZrC, HfC, and ZrC/ZrxSiycomposite ceramic coatings were prepared on the surface of carbon-matrix composites via molten salt solid–liquid two-phase diffusion to improve the ablation resistance of the C/C composites. The preparation of the coating composition could be controlled by using different powders. The effects of temperature and holding time on the microstructures of ZrC coatings and their variation laws were studied. Results showed that the ZrC coating density increased with temperature and holding time. At a holding time of 16 h, the growth of the ZrC coating was slow. The volatilization of SiO2caused loose ZrO2to splash. Moreover, the Si content was found to affect the ablation performance of the ZrC/ZrxSiycomposite ceramic coatings, and the ablation mechanism was studied. The ZrC, HfC, and ZrC/ZrxSiycomposite ceramic coatings exhibited good ablation properties. The ablation rates of the ZrC and HfC coatings were 0.805 and 0.715 mg/s, respectively, after oxyacetylene flame ablation at 3000 °C for 60 s.

To investigate the corrosion behavior of WC–Co composite coating, plasma transferred arc (PTA) welding was applied to prepare WC–Co coating on hull steel EH40 for achieving good metallurgical bonding. The phases of coatings were mainly composed of WC particles, solid solution γ-Co, Fe3Ni2, SiO2and Mo2C. After electrochemical test, it can be concluded that Co-based coating with 45% WC content has better corrosion resistance in low temperature marine environment for obtaining denser oxide film. Through X-ray photo electron spectroscopy (XPS) analysis, the main corrosion products of immersion were Co(OH)2and Co3O4. These corrosion products aggregate to form a stable corrosion product film, which plays some protective role for the coating. Hard particle WC is also partially oxidized to WO3. The pitting hole of 60% WC is the most serious. Pitting corrosion is easy to occur at the interface defects.

In this paper, four kinds of coatings Ni + 30% WC, Ni + 15% WC, Ni, and Co are prepared on EH40 steel by laser cladding technology. Electrochemical experiment tests at a simulating low-temperature (–40°C) environment in 0.5 mol·L−1hydrochloric acid (HCl) solution and 3.5 wt% NaCl solution were conducted, and the polarization curve and electrochemical impedance spectroscopy (EIS) impedance spectrum were obtained. The results show that the Ni + 15% WC coating has the smallest corrosion current and 0.5 mol·L−1HCl solution and 3.5 wt% NaCl solution have the maximum polarization resistance and impedance arc. Coatings will be treated in a 0.5 mol·L−1HCl solution and 3.5 wt% NaCl solution at –40°C immersion for 30 days; finally, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used for test passivation films of Ni + 15% WC samples and sample surface morphology after corrosion. XPS results show that Fe, Mo, and Ni elements can form metal oxides in the 0.5 mol·L−1HCl solution, and Cr, Fe, Mo, Ni, and W elements can form metal oxides in the 3.5 wt% NaCl solution. SEM results display that relatively severe corrosion appeared on the substrate near tungsten carbide in a 0.5 mol·L−1HCl solution, and coating will be corroded form inside of the coating owing to the corrosive solution will penetrate the substrate. In 3.5 wt% NaCl solution, severe corrosion of the substrate has not been observed; however, the binding part has been obviously corroded.

Ophiocordyceps sinensis (O. sinensis) seems to be able to alleviate airway epithelial cell senescence in chronic obstructive pulmonary disease (COPD). The objective of the study is to evaluate the effect of O. sinensis on airway epithelial senescence in the COPD model both in vitro and in vivo. We observed the expression of P16 and P21 in the airway epithelia of 30 patients with COPD. The optimal concentration of O. sinensis and exposure time of the cigarette smoke extract (CSE) were determined in vitro, and senescence-associated β-galactosidase (SA-β-gal) and 5-bromodeoxyuridine (BrdU) were used to evaluate the senescence and proliferation of human bronchial epithelial (16HBE) cells pretreated with O. sinensis by staining kits. COPD model rats were treated with O. sinensis at various concentrations to determine the changes in P16 and P21 expression in airway epithelial tissues. It was found that the expression levels of P16 and P21 were higher in the airway epithelia of COPD patients than those in the control group based on immunohistochemical staining, real-time quantitative PCR, and western blotting. The CSE could induce 16HBE cell senescence, and O. sinensis could alleviate CSE-induced senescence and promote the proliferation of 16HBE cells. The expression levels of P16 and P21 were also higher in the airway epithelia of COPD model rats; however, the levels of P16 and P21 in the groups treated with all concentrations of O. sinensis were obviously lower than those in the COPD model group based on real-time quantitative PCR and western blotting. In conclusion, the CSE can induce airway epithelium senescence, and O. sinensis can inhibit CSE-induced cellular senescence, both in vitro and in vivo.