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81.
The wear characteristics of a polyurethane (PU) hydraulic seal were investigated using a hydraulic seal tester and a pin-on-plate reciprocating tribo-tester, and the results were compared to field data with the aim of developing an accelerated wear test method for hydraulic seals. Tests using a hydraulic seal tester and a pin-on-plate reciprocating tribo-tester were found to reproduce abrasive wear of PU from the field. However, a significant compression set was observed from the test using the hydraulic seal tester. Motivated by the occurrence of abrasive wear from the field, the discolored lubricant and the lubricant with alumina particles were further used for testing using the pin-on-plate reciprocating tribo-tester. The height decrease data of the sealing surface showed that the wear was accelerated by factors of 2.1–3.4 using these degraded lubricants. The outcomes of this work are expected to aid in the design of reliable accelerated life testing for hydraulic seals. 相似文献
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Surface treatment (ST) of carbon fibers (CF) leads to an enhancement in fiber‐matrix adhesion. However, it deteriorates the strength of a fiber which makes its reinforcing action less effective in a composite. These effects in opposite directions control the net strength of a composite, and hence, the treatment has to be judiciously applied, which would enhance the first factor and minimize the second one. Authors have recently reported on four effective techniques (using various doses) such as treatments with nanoparticles of Ytterbium fluoride (YbF3), cold remote nitrogen–oxygen plasma (CRNOP), γ‐ray irradiation and nitric acid oxidation. Amongst these methods, nitric acid oxidation is studied in depth in the literature, and γ‐ray irradiation is sparingly studied. However, nano‐YbF3 and CRNOP were first time reported in the literature by the authors. However, comparative aspects of all these methods were not addressed. In this paper, these aspects in details are discussed to lay down the right criteria for selection of a ST technique of CF to design the desired performance of a composite. The composites with polyetherimide and treated CF (including untreated) were developed and evaluated for various properties including tribological one. Treated CF based composites exhibited excellent mechanical and tribological properties (under harsh operative conditions with wear rates ≈ 1 × 10?15 m3/Nm and μ ≈ 0.09). It was concluded that for strength and tribo‐performance, different treatments and doses are to be employed. Overall nanosized‐YbF3 treatment of CF proved to be the most promising ST method. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
85.
低温盐浴渗氮对Custom 465钢耐蚀及耐磨性的影响 总被引:1,自引:0,他引:1
为了提高Custom 465马氏体沉淀硬化不锈钢的耐磨性,分别在440、480和520℃对580℃时效后的样品进行了2 h的盐浴渗氮,使用显微硬度计、X射线衍射仪、电化学工作站、球盘式摩擦磨损仪、表面轮廓仪、扫描电镜等设备,研究渗氮温度对Custom 465钢表面物相、硬度、渗层显微形貌、耐蚀性及耐磨性的影响. 随着渗氮温度升高,耐蚀性逐渐降低,但表面硬度增加,520℃处理后表面硬度增大到1240 HV,较未处理试样的400 HV明显上升,渗层厚度达到22μm. 440℃渗氮后表面物相为氮在马氏体基体中过饱和的α'N ,点蚀电位降低约60 mV;480℃时有少量CrN相析出,引起点蚀电位降低约180 mV,同时磨损体积下降约43%;520℃时CrN相的含量明显升高,自腐蚀电位降低约70 mV,无明显的稳态钝化区,磨损体积降低82%,减磨效果明显. 相似文献
86.
《Arabian Journal of Chemistry》2022,15(9):104053
Multidrug resistance (MDR) is one of the major global threats of this century. So new innovative approaches are needed for the development of existing antibiotics to limit antibacterial resistance. The current study was aimed to utilize extracts of root, stem, and leaves of Persicaria hydropiper for the synthesis of silver nanoparticles (AgNPs) using standard procedure. Synthesis of AgNPs was evident from the change in color of the solution to dark brownish and then it was further revealed by UV–Vis and Fourier Transformed Infrared Spectroscopy (FTIR). UV–Vis spectroscopy has revealed absorbance peak at 370 nm while, FTIR spectrum displayed that aromatics amines were used as reducing agent in the fabrication of AgNPs. In addition, Scanning Electron Microscopy (SEM micrograph) displaying tetrahedron, spherical and oval shapes of synthesized AgNPs whereas, average size of synthesized AgNPs was found in the range of 32–77 nm. Beside this, it was also observed that the potency of antibiotics against MDR bacteria increased after coating with synthesized AgNPs i.e., the potency of Ceftazidime and Ciprofloxacin increased up to 450% and 500% against Bacillus respectively while, the potency of Gentamicin, Vancomycin and Linezolid increased up to 150%, 200% and 58% against Bacillus, Staphylococcus, and Proteus species respectively. Furthermore, it was concluded that utilizing AgNPs in combination with commercially available antibiotics would provide an alternate therapy for the treatment of infectious diseases caused by MDR bacteria. 相似文献
87.
A novel fluorinated chain extender, (1‐(ethyl(2‐hydroxyethyl)amino)‐3‐ ((3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl)oxy)propan‐2‐ol) (FPO), was synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and elemental analysis. Poly (ether urethane)s containing various amounts of the chain extender with fluorinated side chains (FPUs) were prepared by isophorone diisocyanate (IPDI), polytetra‐methylene‐ether‐glycol (PTMG), 3‐aminopropyltriethoxysilane (KH‐550), and 1,4‐butandiol (BDO). Films of FPUs were investigated by water absorption, contact angle, pencil hardness, adhesive force, and thermal analysis. Coating FPUs on micro‐nano concave‐convex structure plate realizes superhydrophobic performance. Scanning electron microscope (SEM) and atomic force microscopy (AFM) demonstrated that there is a lot of irregular concave‐convex structure, which forms a typical air cushion model. X‐ray photoelectron spectroscopy (XPS) analysis showed that surface fluorine content is 165% more than that of film average fluorine content. The superhydrophobic plate with 10% or higher F‐containing FPUs coating is of outstanding chemical corrosion resistance, excellent solvent resistance, and wear resistance. 相似文献
88.
电镀金刚石刀具钻削碳纤维复合材料磨粒磨损特征研究 总被引:1,自引:0,他引:1
采用电镀金刚石钻磨组合刀具钻削碳纤维复合材料能够有效地减小或消除毛刺和分层等加工缺陷,刀具的使用寿命主要取决于电镀金刚石磨粒的使用寿命.为此,对研制的刀具表面电镀金刚石磨粒的加工磨损形态进行了系统的统计观测.研究结果表明:采用电镀金刚石钻磨组合刀具钻削T300碳纤维复合材料过程中,电镀层的金刚石磨粒具有独特的初期不稳定磨损、混合磨损和正常磨损3个阶段,其磨损形态与钻削产生的轴向力具有显著的线性关系.随着钻孔数目的增加,钻磨孔的轴向力逐渐增大,但是加工出的孔径在刀具经过初期磨损后仍然能够较长时间地稳定在0.024mm误差范围内. 相似文献
89.
Michio Kurosu Katsuhiko Mitachi Junshu Yang Edward V. Pershing Bruce D. Horowitz Eric A. Wachter John W. Lacey III Yinduo Ji Dominic J. Rodrigues 《Molecules (Basel, Switzerland)》2022,27(1)
Rose bengal has been used in the diagnosis of ophthalmic disorders and liver function, and has been studied for the treatment of solid tumor cancers. To date, the antibacterial activity of rose bengal has been sporadically reported; however, these data have been generated with a commercial grade of rose bengal, which contains major uncontrolled impurities generated by the manufacturing process (80–95% dye content). A high-purity form of rose bengal formulation (HP-RBf, >99.5% dye content) kills a battery of Gram-positive bacteria, including drug-resistant strains at low concentrations (0.01–3.13 μg/mL) under fluorescent, LED, and natural light in a few minutes. Significantly, HP-RBf effectively eradicates Gram-positive bacterial biofilms. The frequency that Gram-positive bacteria spontaneously developed resistance to HP-RB is extremely low (less than 1 × 10−13). Toxicity data obtained through our research programs indicate that HP-RB is feasible as an anti-infective drug for the treatment of skin and soft tissue infections (SSTIs) involving multidrug-resistant (MDR) microbial invasion of the skin, and for eradicating biofilms. This article summarizes the antibacterial activity of pharmaceutical-grade rose bengal, HP-RB, against Gram-positive bacteria, its cytotoxicity against skin cells under illumination conditions, and mechanistic insights into rose bengal’s bactericidal activity under dark conditions. 相似文献
90.