Double-layer Ni-P coatings with low phosphorus content in the inner layer and high phosphorus content in the outer layer and Ni-Mo-P composite coatings are successfully prepared on the surface of AZ91D magnesium alloy by chemical plating process. The microstructures, friction and corrosion resistance of double-layer Ni-P and Ni-Mo-P coatings are studied in comparison. Meanwhile, the deposition and corrosion resistance mechanism for the coatings are investigated. Results convey that both Ni-P and Ni-Mo-P coatings showcase an amorphous structure. The coating possesses denser and more homogeneous structure with the co-doping of Mo. The micro-indentation hardness (859.7 HV) and friction coefficient (0.58) of Ni-Mo-P coatings show that the ternary alloy coating is firmly bonded to the magnesium alloy substrate. Besides, the Ni-Mo-P coatings demonstrate exceptional wear resistance attributed to Mo co-deposition, fostering grain refinement and facilitating the growth of passivation films.

Abstract LaoXiangHuang (LXH) is a medical pickled fruit made of fresh finger citron (Citrus medica L. var. sarcodactylis) in Chaozhou, China. Aging is a process to strengthen the efficacy of Laoxianghuang (LXH), which is related to the activity of microorganisms. In this study, the changes of the microbial community of LXH within the three-years aging process were analyzed by high-throughput sequencing (HTS). According to alpha diversity results, bacterial abundance and diversity were higher than those of fungi. A total of 3 phyla and 13 bacterial genera were identified whereas 2 phyla and 4 fungal genera were identified. Meta-taxonomic of the overall bacterial communities in samples revealed that Halomonas spp. was the most abundant genus in all samples, which showed the first decresed, and then increased and decreased finally. The followed by Nitriliuptor spp., Nesterenkonia spp., Weissella spp., Notinibacter spp., Streptococcus spp., Nocardiopsis spp., Acinetobacter spp., Ralstonia spp., Lactobacillus spp. and unassigned genus. The unassigned genera (through the whole three-years fermentation period), Ustilago spp., Malassezia spp., Aspergillus spp. and Schizophyllum spp. were the predominant fungal genera. The result of PCOA and T-test analysis exhibited that the samples with different aging times have significant differences and are mainly reflected in Halomonas, unassigned bacterial genera, Nitriliruptor, Nesterenkonia, Weissella, Intestinibacter, Streptococcus and Nocardiopsis, Lactobacillus, Acinetobacter, Ralstonia, unassigned fungal genera, Ustilago spp. Malassezia spp. Aspergillus spp. and Schizophyllum spp., which may have important potential in promoting the aging process of LXH. This study helps us to understand the dynamic change of microorganisms of LXH during the aging process and provides a research basis for shortening the aging time of LXH in the future.

Ni-Co alloy and ZrO2 micron particles were codeposited on 45 carbon steel by electrodeposition. The composition and microstructure of the composite coating were characterized. The high temperature tribological properties were carried out by a pin-on-disk tribo-tester. Additionally, the oxidation resistance was evaluated via high temperature circulating oxidation test. The results indicated that the deposited composite coating showed dispersed ZrO2 particles and continuous Ni-Co matrix, and there were no obvious pores, cracks and other defects at the interface between the composite coating and the substrate. The embedded ZrO2 particles changed the friction mechanism from adhesive wear to abrasive wear, the wear loss rate and friction coefficient of Ni-Co-ZrO2 composite coating were lower in comparison with that of Ni-Co alloy coating and carbon steel substrate. In addition, the embedded ZrO2 particles exerted a reactive-phase effect on the growth of nickel oxide and cobalt oxide, and effectively reduced the oxidation rate of the substrate at high temperature. Therefore, the Ni-Co-ZrO2 composite coating presents better oxidation resistance, when compared with Ni-Co coating.