共查询到18条相似文献,搜索用时 10 毫秒
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选用石墨烯和氧化石墨烯作为水基润滑添加剂,对比研究两种纳米材料对AZ31镁合金在冷轧过程中的摩擦学性能的影响。采用场发射扫描电镜(FESEM)和拉曼光谱仪(Raman)对石墨烯和氧化石墨烯水基润滑液润滑条件下轧后板材表面形貌和成分进行了分析,探讨了石墨烯和氧化石墨烯作为水基润滑添加剂的润滑机理。结果表明,石墨烯和氧化石墨烯在水中最优含量为0.5%(质量分数),摩擦因数分别为0.132和0.038,磨损体积分别为23.1 mm^3和2.59 mm^3。同时氧化石墨烯水基润滑液优良的润滑性能降低了镁合金轧制过程中的轧制力,改善了轧后板材表面质量。相同测试条件下,氧化石墨烯水基润滑液的润滑性能优于石墨烯水基润滑液,主要原因是其在水中良好的分散性和在镁合金表面优异的润湿性。 相似文献
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Ateyya A. Aboul-Enein Enas I. Arafa Samira M. Abdel-Azim Ahmed E. Awadallah 《Fullerenes, Nanotubes and Carbon Nanostructures》2021,29(1):46-57
AbstractCarbon nanotubes (CNTs) are attracting great interest in enhancing rheological behavior and thermal performance of lubricating grease. In this study, CNTs were synthesized by catalytic chemical vapor deposition (CCVD) method using low-density polyethylene (LDPE) waste as a cheap carbon source and Co/MgO as an effective catalyst. The effect of temperature on the catalytic pyrolysis of LDPE to produce CNTs has been studied. Catalytic pyrolysis of LDPE waste was conducted in a temperature range of 350–600?°C using the H-ZSM-5 catalyst. The structure and quality of CNTs were fully characterized using HR-TEM, XRD, and Raman spectroscopy. On the other hand, various concentrations of CNTs (0.2, 0.4, 0.6, 0.8, and 1.0?wt%) were mixed with pure lithium grease to determine the optimum percentage that improves the properties of nano-grease. The results showed that a high yield of multiwalled carbon nanotubes (MWCNTs) was obtained with high quality at temperatures ranging from 400 to 550?°C. Also, the addition of CNTs enhanced the rheological behavior of lithium grease, and the optimum percentage of CNTs was 0.8?wt%. Furthermore, the apparent viscosity and shear stress of lithium nano-grease increased by increasing the concentration of CNTs up to 0.8%. At this concentration, the penetration value of lithium nano-grease was greater than pure grease, and the dropping point increased by 12.5%. These results suggested that CNTs prepared from LDPE waste were an excellent additive to enhance the physicochemical properties of lithium grease. 相似文献
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AbstractA simple two-step aqueous polymerization method was introduced to synthesize a polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. On the basis of the effects of the ratio of PAC to PEG, neutralization degree, heavy-metal ion concentration, and temperature on the adsorption behavior of PAC/PEG IPN hydrogel toward Ni2 +, Cr3 + and Cd2 +, the preparation conditions were optimized. In our system, the greatest amount of Ni2 +, Cr3 + and Cd2 + adsorbed were 102.34, 49.38 and 33.41 mg g- 1, respectively. The adsorption abilities of a dried PAC/PEG composite and a swollen PAC/PEG IPN hydrogel were compared. It was found that the efficiency of removing metal ions using the swollen hydrogel was greater than that using the dried composite. The adsorption mechanism and model are also discussed. 相似文献
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Qunwei Tang Xiaoming Sun Qinghua Li Jihuai Wu Jianming Lin 《Science and Technology of Advanced Materials》2009,10(1)
A simple two-step aqueous polymerization method was introduced to synthesize a polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. On the basis of the effects of the ratio of PAC to PEG, neutralization degree, heavy-metal ion concentration, and temperature on the adsorption behavior of PAC/PEG IPN hydrogel toward Ni2 +, Cr3 + and Cd2 +, the preparation conditions were optimized. In our system, the greatest amount of Ni2 +, Cr3 + and Cd2 + adsorbed were 102.34, 49.38 and 33.41 mg g- 1, respectively. The adsorption abilities of a dried PAC/PEG composite and a swollen PAC/PEG IPN hydrogel were compared. It was found that the efficiency of removing metal ions using the swollen hydrogel was greater than that using the dried composite. The adsorption mechanism and model are also discussed. 相似文献
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Ionic liquid functionalized graphene oxides (GOs-IL) were synthesized by the amidation and cation-π stacking, and their tribological property as the water-based lubricant additives was investigated. The GOs-IL exhibited superior friction-reducing and antiwear performance. Specifically, under the same test conditions, the mean friction coefficient and wear volume of 0.02 wt% GOs-IL/base liquid suspension were 57% and 76% lower than that of base liquid. The worn surface analyses revealed that the boundary tribofilm composed of the GOs-IL deposition film and chemical reaction film should formed on the wear scar lubricated by the GOs-IL/base liquid suspension. The proposed lubrication mechanism illustrated that the IL functional groups of GOs-IL improved their absorption and embedded stability on the rubbing surfaces by the electrostatic interactions, and then promoted the formation of the above boundary tribofilm. The tribofilm directly prevented the rubbing surfaces from the immediate contact and hence greatly reduced the friction and wear. 相似文献
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聚乙二醇改性聚乳酸嵌段共聚物的合成与亲水性研究 总被引:1,自引:1,他引:1
以DL-丙交酯和分子量Mn=400、1000和2000聚乙二醇(PEG)为原料,在辛酸亚锡催化下开环聚合制备了聚乳酸(PLA)-聚乙二醇-聚乳酸三嵌段共聚物(PLEG)。考察了催化剂用量、反应时间对产率和[η]的影响。用FT-IR、1 H-NMR、GPC、DSC、XRD、静态水接触角等对共聚物进行了表征和性能测试。结果表明,催化剂用量为0.2%、反应时间分别为PLEG400共聚物2~4h、PLEG1000共聚物4~8h和PLEG2000共聚物8~12h较宜;共聚物组成比与投料比较一致,共聚物的数均分子量与理论计算值较一致;共聚物为无定形态,PEG的引入使共聚物Tg明显低于PLA均聚物,且随PEG的Mn减小,共聚物的Tg随之降低;而且PEG的引入明显提高了PLA的亲水性,PEG的Mn越小,PLA亲水性的提高程度越大。通过控制催化剂用量和反应时间,150℃可以得到分子量符合投料组成比要求、亲水性有明显提高的PLA-PEG-PLA三嵌段共聚物。 相似文献
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通过原位聚合法制备了以正十二烷醇(DA)为芯材,密胺树脂(MF)或聚乙二醇改性密胺树脂(PMF)为壁材的相变微胶囊DA@MF和DA@PMF,并将相变微胶囊添加到木粉/高密度聚乙烯复合材料(WF/HDPE)中,制备了具有相变蓄热能力的DA@MF-WF/HDPE和DA@PMF-WF/HDPE复合材料。采用DSC、TG和红外热成像等方法对DA@MF、DA@PMF和相变微胶囊-WF/HDPE的热性能进行了分析与表征。测试结果表明,DA@PMF的结晶和熔融热焓值分别提高了35.0J/g和21.5J/g,快速失重温度提高了19.9℃;蓄热能力测试表明,DA@PMF成功添加至WF/HDPE中,且在制备过程中损失较小;DA@PMF-WF/HDPE的相变温度(27.2、11.3℃)、相变潜热(31.6、20.3J/g)和热稳定性(256.9℃,DA开始失重)等性能表明其具备成为相变蓄热材料的潜力。 相似文献
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Wenlong Yang Lei Niu Jinqiang Zhao Chengcheng Wang Xiaoqi Liu 《Particulate Science and Technology》2018,36(7):844-849
The surface of nano-Sb2O3 particles was modified with polyethylene glycol (PEG) using the mechanochemical method, and the dispersion mechanism of modified nano-Sb2O3 particles was also discussed. The modified nano-Sb2O3 particles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and UV absorbance. The results showed that the surface of nano-Sb2O3 particles was successfully coated by PEG molecules through the effect of hydrogen bonding, and the dispersion of nano-Sb2O3 particles in ethyl alcohol (C2H5OH) was significantly improved. Due to the different adsorption conformations of PEG molecules, the dispersion stability of nano-Sb2O3 particles was gradually improved with the increase of PEG average molecular weight and concentration. However, the superfluous PEG molecules would weaken the dispersion stability of nano-Sb2O3 particles. 相似文献
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采用化学还原法和球磨共混添加法制备了纳米坡缕石/铜(P/Cu)复合材料,采用粒度分析仪和透射电子显微镜(TEM)对复合纳米粒子的粒度和形貌进行表征。利用四球摩擦磨损试验机考察了不同纳米P/Cu添加量和不同P与Cu配比的复合粉体作为润滑油添加剂对高副钢球摩擦副的摩擦学性能,利用扫描电子显微镜(SEM)、X射线能谱仪(EDS)对摩擦表面进行形貌、元素性能分析。结果表明,所制备的纳米P/Cu粒径基本小于100 nm,分散稳定性良好,在纳米P/Cu为1wt%且P:Cu=3:1(质量比)添加量下表现出最优的摩擦学性能,其钢球磨斑直径比基础油的减小了20.7%。纳米P/Cu可在摩擦表面生成含Mg、Al、Si和Cu等元素的自修复膜,补偿摩擦磨损且使摩擦表面变光滑。 相似文献
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Pristine single-walled carbon nanotubes (CNTs) were dispersed in the room-temperature ionic liquid (IL) 1-octyl, 3-methylimidazolium tetrafluoroborate ([OMIM]BF4) by grinding and ultrasounds. Excess IL was removed to obtain single-walled carbon nanotubes modified by [OMIM]BF4 (mCNTs). mCNTs were added in a 1 wt.% to polystyrene (PS), polymethylmethacrylate (PMMA) and polycarbonate (PC) to obtain PS + mCNT, PMMA + mCNT and PC + mCNT. The dry tribological performance of the new nanocomposites was studied against AISI 316L stainless steel pins and compared with that of the neat polymers and with the nanocomposites containing pristine carbon nanotubes without IL (PS + CNT; PMMA + CNT and PC + CNT). The maximum wear rate and friction coefficient reduction is obtained for PS + mCNT. Results are discussed upon the basis of optical, SEM and TEM microscopy, thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). 相似文献
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Facile synthesis of fluorescent carbon dots using watermelon peel as a carbon source 总被引:1,自引:0,他引:1
The synthesis of water-soluble fluorescent carbon dots (C-dots) has received much attention recently. Here, high quality fluorescent C-dots have been synthesized through low-temperature carbonization and simple filtration using watermelon peel, a waste and reproducible raw resource, as a novel carbon resource. This facile approach allows large-scale production of aqueous C-dots dispersions without any post-treatment process. The as-prepared C-dots possess small particle sizes (~ 2.0 nm), strong blue luminescence, acceptable fluorescence lifetime and good stability in a wide range of pH values (pH 2.0-11.0) and at a high salt concentration. Besides, the obtained C-dots have been successfully applied in live cell imaging, indicating these carbon nanoparticles can serve as high-performance optical imaging probes. 相似文献
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以正十二烷醇(DA)为芯材,密胺树脂(MF)和聚乙二醇改性密胺(PMF)树脂为壁材制备了相变微胶囊(MicroPCMs),并分别添加到木粉/高密度聚乙烯(WF/HDPE)复合材料中,获得了具有相变蓄热能力的MicroPCMs-WF/HDPE复合材料。采用SEM、FTIR和纳米压痕等方法对MicroPCMs的表面形态、力学性能进行了分析与表征,同时对MicroPCMs-WF/HDPE复合材料的物理力学及热性能进行了测试。结果表明:经聚乙二醇改性后,改性微胶囊(PMF-MicroPCMs)的弹性模量和硬度较未改性微胶囊(MF-MicroPCMs)分别增加了13.9%和30.0%;MicroPCMs-WF/HDPE复合材料的熔融温度区间(22.2~28.7℃)满足人体舒适温度范围,较纯WF/HDPE复合材料温度变化速率明显减缓;相比纯WF/HDPE复合材料,MicroPCMs-WF/HDPE复合材料的吸湿性、冲击强度和表面硬度增加,弯曲和拉伸性能下降;PMF-MicroPCMs-WF/HDPE复合材料的性能均优于MF-MicroPCMs-WF/HDPE复合材料,且达到了木塑装饰板材的力学性能标准要求。 相似文献
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A simple, rapid and energy efficient approach based on copper mediated chemical reduction — solvothermal method was employed to prepare submicron size hollow carbon spheres (SHCS) using carbon tetrachloride as carbon source. The obtained SHCS were characterized by means of various physico-chemical techniques like nitrogen adsorption-desorption measurements at 77 K, XRD, SEM, TEM, EDX and FT-Raman techniques. Thus characterized samples displayed macroporous nature of carbon with carbon and chloride contents of about 73% and 12% on atomic basis respectively. The presence of chloride content may open new avenues for surface modifications of SHCS in the area of catalysis and separation science. 相似文献
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Asep Bayu Dani Nandiyanto 《Materials Letters》2009,63(21):1847-1850
Boron nitride (BN)/carbon nanotube (CNT) composite particles in submicrometer-sizes were successfully prepared using a spray pyrolysis method. Using an ultrasonic nebulizer, BN nanoparticles, ferrocene (as catalyst), and ethanol (as solvent and carbon source) were sprayed into a tubular furnace (fixed temperature of 800 °C) under an Argon flow of 1 L/min. Ethanol was used as a solvent as well as a carbon source because of its non-polluting nature, low cost, harmless byproducts (e.g. CO), and ease of handling. An aggregated BN particle with the growth of a multiwall-CNT (10 nm in thickness) on the surface could be produced. No BN phase changed because the process was completed in a matter of seconds. The present novel synthesis method could be broadly applied in the fabrication of various composite materials with the growth of CNT on the particle surface using a simple, fast and continuous process. 相似文献