Epoxy nanocomposite coatings play an important role in the wear protection of steel exposed in harsh service environments. How to improve the mechanical and wear resistance of coatings through filler addition is necessary to meet the industry application requirements. In the present paper, an epoxy-based nanocomposite coating was developed with addition of titanium dioxide (TiO 2 ), graphite, short carbon fibers (SCFs), and zinc sulfide (ZnS) for enhancement in mechanical, bonding to steel, and tribological performances.The reciprocating friction and wear performances of the coatings were investigated at room temperature and 100 C. The addition of nanometer sized TiO 2 and SCFs increased the tensile properties remarkably, while the addition of graphite and ZnS deteriorated the tensile properties. The fillers of graphite and ZnS had no obvious weakening effect on the interfacial shear strength between the coatings and steel, despite the solid lubrication of graphite and weak stiffness of ZnS. Compared with the epoxy sample, the wear rate of the coating filled with optimized filler combination (TTGCS5) was reduced by 19.5 times at room temperature and 25.9 times at 100 C. Addition of ZnS increased the wear resistance more pronounced compared to that of graphite at 100 C, which was attributed to formation of a compact, continuous and stable selflubricating transfer film on the coating surface. The optimized content of fillers was established for an epoxy coating to obtain the best friction rates of 0.51 and 0.56 (10 À4 mm 3 /[NÁm]) at 25 and 100 C, respectively.
Agapanthus praecox has become a burgeoning variety in the flower market due to its high ornamental value with unique large blue-purple inflorescence. For rapid entering into the market, tissue culture technology or organogenesis has an attractive application over the conventional reproduction approach. In this study, a highly efficient protocol based on indirect organogenesis has been successfully established for A. praecox subsp. orientalis ‘Big Blue’. Two types of explants, root tips versus root segments, were compared for callus induction frequency in response to the induction culture media. The induction media contain Murashige and Skoog’s (MS) Basal Salt supplemented with various concentrations of picloram (PIC), 2,4-Dichlorophenoxyacetic acid (2,4-D), thidiazuron (TDZ), kinetin (KT) and naphthalene acetic acid (NAA). Of the two types of explants, root tips were found to be more effective for callus induction than root segments. Among the induction media tested, the highest callus induction rate (100.00%) was achieved when cultured on MS supplemented with 2.0 mg/L PIC, 1.5 mg/L KT and 0.1 mg/L NAA, which was probably accredited to higher endogenous phytohormone contents, especially of 3-indoleacetic (IAA). The optimal medium for callus proliferation was MS + 1.0 mg/L PIC + 1.0 mg/L 6-BA + 0.4 mg/L NAA, and the fresh weight increased by 72.74%. After being transferred onto the adventitious bud induction medium for 25 days, shoots were dedifferentiated from the surface of the flourishing callus, which then developed to the plantlet with roots in 90 days. The plantlets were transplanted in a greenhouse with a survival rate of 92.86%. This study innovatively established an indirect organogenesis tissue culture system of A. praecox with roots as explants, which provided a practical reference in its application.
The elevator being used in field application causes several problems such as low level of mechanization and high intensity of labor. Therefore, electromotion elevator is developed and tested in this paper, which works with mechanized workover equipments. On the base of traditional elevator, the safety pin for the rings is driven by a spring and its own gravity, while the door of the elevator, with self-locking function, is driven by a DC motor which is remotely controlled. Through the field test and application, the electromotion elevator shows desirable safety, reliability and continuous working ability, which satisfy the requirement of workover operation.
Abstract. The fixed clamp should be installed inside the BOP stack for sectional blockage and tubing pulling job. When there is combined string in downhole, it causes inconvenience in replacing slips of different specifications because of pressure in BOP stack. To solve the problems mentioned above, variable diameter slip was invented. Different arc's central angle model of slip was set by ANSYS, the oil tube was divided by sweep while the slip was divided randomly. The analysis shows the arc's central angle for clamping ø73 oil tube is 106°and the clamping force meets operation needs and the design requirements.
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