Tribological behaviour of polymeric coatings lubricated with salt water

In many applications, such as marine industries, pumping of underground water, and in some chemical industries, sliding elements are lubricated with the process fluid (e.g. salt water). Therefore, the effect of salt water on the tribological behaviour of metallic friction couples has been a subject of study. In the present work, the influence of salt water solution (3 wt. % sodium chloride) on the tribological behaviour of some polymeric coatings is investigated, using a pin-on-disc testing machine, at different sliding speeds and normal loads. The coating consists of a base-matrix of high-density polyethylene (HDPE) and polyamide (PA6) with different concentrations of copper- and tin-powder fillers. The effect of the formation of the oxide films, sodium hydroxide microlayers (NaOH) and the polymeric transformed films on the friction mechanism, is discussed. The results show that squeeze of the lubricant takes place in the presence of the NaCl-solution; and, despite the relatively low viscosity of the lubricant, hydrodynamic pressure affected the friction mechanism at the sliding speed of 0.50 m/s, resulting in a significant reduction in the coefficient of friction. The value of the coefficient of friction seems also to be affected by the generation of sodium hydroxide, as well as the oxide films and material transfer layers. At a low speed (0.20 m/s), the PA6-based composites with copper-filler showed an optimal wear resistance at normal loads up to 15N.     

港东开发区东一段湖相三角洲沉积规律研究与储集层精细刻画

大港油田港东开发区东一段属于湖相三角洲沉积环境,砂体发育受沉积相控制,空间分布复杂、横向对比预测难,常规资料与地震识别方法难以满足储集层刻画需求。依托新采集的“两宽一高”高精度地震资料,以层序地层学、地震沉积学研究思路为指导,以区域沉积演化规律作为宏观约束,通过建立层序地层格架,应用测井相、地震相识别技术,开展区域沉积相平面特征描述,结合储集层发育特征、含油气性显示结果,多元耦合明确三角洲沉积优势储集相带。应用地震分频和地层切片技术,开展小尺度砂体追踪及属性切片分析,提高三角洲前缘分流河道等薄储集层识别精度,盘活了区块东营组的储量潜力,同时形成一套针对三角洲沉积的优势储集层识别与薄砂体追踪技术系列。     

塑料压力管道热板焊接接头瞬时应力有限元分析

基于热粘弹性积分型本构关系,考虑材料性能依赖于温度变化及相变潜热的影响,利用有限元软件ANSYS热-力耦合及载荷步功能模拟结晶型高密度聚乙烯塑料压力管道热板焊接过程.并对焊接接头的应力分布进行有限元分析,得到了环向、轴向及径向瞬态应力分布规律.采用盲孔法和锯切法测量焊后残余应力,实测结果与数值分析基本吻合.     

铬污染场地电阻率法探测效果研究

为了研究高密度电阻率法对铬污染场地的探测效果,建立了典型铬污染模型,采用有限差分法以及最小二乘法对其进行正反演计算,分析铬污染的电阻率特征,得到了高密度电阻率法不同装置类型下的不同污染程度的探测效果。随后对河北某铬污染场地进行高密度电阻率法探测,得到该厂区地下污染羽的分布范围,探测结果得到了钻孔取芯验证。通过理论分析和实际探测结果表明,地下土体受到铬污染后,其电阻率表现为相对低阻特征,与同层未污染土体存在明显的电阻率差异;随着污染程度减弱,高密度电阻率的识别能力也随之降低,并且不同装置类型的探测效果也存在差异。     

Effects of mechanical recycling on optical properties and microstructure of recycled high-density polyethylene pellets and bottles

The demand for recycling high-density polyethylene (HDPE) utilizing mechanical recycling technologies is currently felt strongly by both society and industry. However, thermal oxidation of the polymer during the recycling process may lead to irreversible changes in the material properties of recycled high-density polyethylene (rHDPE). The effects of mechanical recycling on the optical characteristics and microstructure of rHDPE pellets and bottles were investigated in this study. The results revealed that the apparent color of the rHDPE became more yellow and gray compared to the virgin HDPE (vHDPE), and showed a signal at 670–680 nm in the solar reflectance spectrum. The thermal oxidation of rHDPE considerably raised the absorption intensities of carbonyl, ester, and hydroxyl groups in attenuated total reflection Fourier transform infrared spectrum. In addition, the presence of carbonyl and hydroxyl unsaturated chemicals might make it challenging to recognize the distinctive peaks of vHDPE in the ultraviolet–visible diffuse reflectance (UV–Vis-DIR) spectra at wavelengths less than 400 nm. Thermal oxidation of rHDPE was also confirmed in the C OH, CO, and O CO valence structures of C1s and O1s. A characteristic valence band (VB) profile at 25 eV can be used as the recognizable information for the oxidation of rHDPE. The microstructure of the surface of rHDPE pellets exhibited rough and uneven morphological defects. The higher recycled content made rHDPE bottles' surface morphology rougher and their cross-section microstructure thinner and more porous than vHDPE bottles.     

In Situ Construction of High-Density Solid Electrolyte Interphase from MOFs for Advanced Zn Metal Anodes

Aqueous zinc anode has been re-evaluated due to the superiority in tackling safety and cost concerns. However, the limited lifespan originating from Zn dendritic and side reactions largely hamper commercial development. Currently, the coating prepared by simple slurry mixing is leaky and ineffectively isolate sulfate and water. Herein, inspired by the DFT calculations and the easy hydrolysis characteristic of MIL-125 (Ti), an in-situ grown high-dense TiO_2-x solid electrolyte interphase (HDSEI) with rich oxygen vacancies is successfully constructed in an aqueous electrolyte, in which the oxygen vacancies not only strengthen the hydrogen binding force thereby inhibiting the hydrogen precipitation by-reaction, but also reduce the migration energy barrier of zinc ions and enhance the mechanical properties. Profiting from the HDSEI, symmetric Zn cells survive up to remarkable 4200 h at 1 mA cm⁻², nearly 42-times than that of bare Zn anodes. In situ optical microscopy clearly reveals that the in situ grown HDSEI homogenizes the zinc deposition process, while bare zinc without HDSEI shows significant dendrites, confirming the protective nature of HDSEI. Furthermore, full Zn ion capacitors can deliver excellent electrochemical performance, providing a feasible in situ approach to construct HDSEI to implement dendrite-free metal anodes.     

Development of a compact high-density blue core helicon plasma device under 2000 G magnetic field of ring permanent magnets

A helicon wave plasma source in a tube of ring permanent magnets (PMs) has been constructed to study the effect of the configuration of the magnetic field with zero magnetic points on plasma parameters. This device also serves as an exploration platform for a simple, compact helicon wave plasma source adaptable to engineering applications. A small-diameter (26 mm) high-density (∼1018 m−3) blue core plasma is produced in ∼1 Pa argon by helicon RF (radio-frequency) discharge using a Nagoya III antenna under magnetic field (∼2 kG) of compact ring PMs (length ∼204 mm). Operational parameters, i.e. RF power and neutral gas pressure are scanned and plasma density is measured by an RF compensated probe to explore the operating characteristics of the device. Iconic feature of a helicon discharge, such as blue core plasmas and E-H-W mode transitions are well observed in the device, despite the wavelength calculated using the conventional dispersion relation of a bounded whistler waves (Chen 1991 Plasma Phys. Control. Fusion 33 339) is order of magnitudes longer than the length of the plasma in this device which seems to suggest that such helicon device is impossible. Surprisingly, the wavelength calculated by the unbounded whistle wave dispersion formula in turn suggests the occurrence of a half wavelength resonance.     

Bio-based compatibiliser enhancing the interface properties of CaCO3/recycled high-density polyethylene composites

The fabrication of composites of two or more materials with different polarities requires the use of compatibilisers to improve interface properties. However, most compatibilisers used for industrial production are derived from the cracking products of petroleum, which is a limited resource susceptible to price fluctuations and pollutes the environment. In this study, a new compatibiliser derived from renewable plant-oil-based products, ESO–G–OA, was designed and synthesized using epoxy soybean oil, oleic acid, and glycerol. Scanning electron microscopy results showed that ESO–G–OA can effectively improve the dispersion of CaCO₃ in a recycled high-density polyethylene (reHDPE) matrix and reduce the interfacial gap between the two phases. The analysis of the mechanical properties showed that the ESO–G–OA-modified composite has higher tensile and impact strength than unmodified samples. The ESO–G–OA modification improved the thermal stability and melt flow of the composite and reduced the energy consumption during processing. Moreover, the excellent compatibility of ESO–G–OA can improve the comprehensive properties of CaCO₃/reHDPE composites, compensating for the performance reduction caused by the multiple processing steps necessary to obtain reHDPE. This confirmed that ESO–G–OA has promising application prospects in the production of composites requiring compatibilisers.