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Experimental study on the wear behavior of HVOF sprayed nickel-based coating
Chao Zheng,Yonghong Liu,Jie Qin,Renjie Ji,Shihong Zhang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1
Severe wear is a hot issue in the development of petroleum engineering which has attracted many attentions. To address this problem, a nickel-based alloy (NiCrBSiWFeCoC) coating was proposed and prepared using High-velocity oxy-fuel (HVOF) technique. The wear properties of as-sprayed composite coating were studied. The sliding wear experiments of both as-sprayed and uncoated specimens were conducted on a tribometer. The obtained results indicated that the both wear rates increased obviously with the increase in normal load, however, the friction coefficients decreased with the increase in normal load. Based on the comprehensive analyses, it can be concluded that the as-sprayed coating exhibited better wear resistance. Furthermore, the wear behaviors can be investigated by analyzing the worn morphologies. This research can provide insight into the wear prevention in petroleum engineering and decreases the failure of equipments or pipelines.
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Influence of heat treatment on the wear life of hydraulic fracturing tools
Chao Zheng,Yonghong Liu,Hanxiang Wang,Jie Qin,Yang Shen,Shihong Zhang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2
Wear phenomenon has caused severe damage or failure of fracturing tools in oil and gas industry. In this paper, influence of heat treatment on the mechanical properties and wear resistance of fracturing tool made of lamellar graphite grey cast iron were investigated. The surface composition and microstructure were characterized by X-ray diffraction (XRD) and metallographic microscope. Sliding wear tests were performed to study the tribological behavior. Tests results showed that wear rates of treated specimens decreased by 33 %. Besides, worn morphology and wear debris were analyzed using Scanning electron microscope (SEM) and Energy dispersive Xray spectra (EDS). Wear failure mechanisms of specimens were identified. Furthermore, on-site experiment results indicated that wear loss of treated samples decreased by 37.5 %. The wear life of hydraulic fracturing tools can be improved obviously by the heat treatment.
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Research on Fracture of Aluminum Foil in Microscale Laser Peen Forming
Chao Zheng,Sheng Sun,Jing Liu,Zhong Ji 한국소성가공학회 2010 기타자료 Vol.2010 No.6
A novel numerical method for dynamic fracture in microscale laser peen forming (μLPF) of aluminum foils was presented and the role of the die diameter on fracture behavior at the ultra high strain rate was investigated via both experimental and numerical methods. μLPF is a process in which the plastic deformation is generated through laserinduced shock wave and compressive residual stresses can be imparted to improve the fatigue life of micro parts. During μLPF, the pressure exerted on the target is higher than 1 GPa and the strain rate is greater than 10? s<SUP>-1</SUP>, so the mechanical behavior of materials in this dynamic process is very different from that under static or quasi-static conditions. In the present study, the finite element method with grain and grain boundary elements was used to analyze the μLPF process of aluminum foils with a thickness of 60 μm. The onset and propagation of crack were simulated in this way that the specified nodes were tied together until the equivalent plastic strain exceeded a certain value. Under a given value of plastic strain, the influence of die diameters of 0.6, 1.0, and 1.6 mm on the fracture mode of the material was predicted. A series of experiments were carried out to verify the numerical model. The geometrical morphologies of fracture regions were observed via optical microscope and scan electron microscope. In results from both experiments and simulations, the size of the die diameter affects the location of the fracture: (I) Fracture appeared at the entrance of the die for die diameters of 0.6 and 1.0 mm. (II) Fracture occurred near the centre of the formed dome for 1.6 mm die diameter. The generation mechanism of two fracture modes was explained. This work provides a preliminary insight into the fracture behavior of materials under the ultra high strain rate and lays the ground work for more in-depth simulations in the future study.
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Circ-SNX27 sponging miR-375/RPN1 axis contributes to hepatocellular carcinoma progression
Chao Zheng,Jin Liang,Shoude Yu,Hua Xu,Lin Dai,Dan Xu The Korean Society of Pharmacology 2023 The Korean Journal of Physiology & Pharmacology Vol.27 No.4
Hepatocellular carcinoma (HCC) is a prevalent malignant tumor with high fatality. It has yet to be reported whether circ-SNX27 can affect the progression of HCC. This study attempted to analyze circ-SNX27's precise role and underlying mechanisms in HCC. HCC cell lines and tumor specimens from HCC patients were analyzed using quantitative real-time PCR and Western blotting to quantify the expressions of circ-SNX27, miR-375, and ribophorin I (RPN1). Cell invasion and cell counting kit 8 experiments were conducted for the evaluation of HCC cell invasion and proliferation. Caspase-3 Activity Assay Kit was utilized to gauge the caspase-3 activity. Luciferase reporter and RNA immunoprecipitation assays were executed to ascertain the relationships among miR-375, circ-SNX27, and RPN1. To determine how circ-SNX27 knockdown affects the growth of HCC xenografts in vivo, tumor-bearing mouse models were constructed. Elevated expressions of circ-SNX27 and RPN1 as well as a reduced miR-375 expression were observed among HCC cells and HCC patient tumor specimens. Knocking-down circ-SNX27 in HCC cells abated their proliferative and invasive abilities but raised their caspase-3 activity. Moreover, the poor levels of circ-SNX27 inhibited HCC tumor growth among the mice. Circ-SNX27 enhanced RPN1 by competitively binding with miR-375. Silencing miR-375 in HCC cells promoted their malignant phenotypes. Nonetheless, the promotive effect of miR375 silencing was reversible via the knockdown of circ-SNX27 or RPN1. This research demonstrated that circ-SNX27 accelerated the progression of HCC by modulating the miR-375/RPN1 axis. This is indicative of circ-SNX27's potential as a target for the treatment of HCC.
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THE INVESTIGATION OF ATOMIC STRUCTURE AND ELECTRIC PROPERTY OF POLYCRYSTALLINE CdS(Se) FILMS
Zheng, Zheng, Yufeng,Ma, Ma, Zhongquan,Deng, Deng, Rengping,Zha, Zha, Chaozheng 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.1
The spray-sintering process and thermal evaporation technique were appliced to fabrication of polycrystalline CdS(Se) films on glass substrate respectively. Their atomic structure and surface morphology were analyzed by XRD and SEM spectrometers. It was found that films made in spraysintering process were of the zince-blende structure but the films evaporated in vacuum showed a two-dimensional layer structure of atom stacked along c axis with a lattice parameter of $3.351{\AA}$. A variation of the conductivity with annealing temperature in air and nitrogen for sintered films with impurities has been ascribed to the mobility and the concentration of majority carrier. A increase of the electric conductance with temperature in any ambience for evaporated films was resulted from forming a conductive layer which promoted the mobilization of eletron or hole. The absorption and desorption of oxygen in subsequent annealing process has alos been discussed.
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