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Cutting fluid has cooling and lubricating properties and is an important part of the field of metal machining. Owing to harmful additives, base oils with poor biodegradability, defects in processing methods, and unreasonable emissions of waste cutting fluids, cutting fluids have serious pollution problems, which pose challenges to global carbon emissions laws and regulations. However, the current research on cutting fluid and its circulating purification technique lacks systematic review papers to provide scientific technical guidance for actual production. In this study, the key scientific issues in the research achievements of eco-friendly cutting fluid and waste fluid treatment are clarified. First, the preparation and mechanism of organic additives are summarized, and the influence of the physical and chemical properties of vegetable base oils on lubricating properties is analyzed. Then, the process characteristics of cutting fluid reduction supply methods are systematically evaluated. Second, the treatment of oil mist and miscellaneous oil, the removal mechanism and approach of microorganisms, and the design principles of integrated recycling equipment are outlined. The conclusion is concluded that the synergistic effect of organic additives, biodegradable vegetable base oils and recycling purification effectively reduces the environmental pollution of cutting fluids. Finally, in view of the limitations of the cutting fluid and its circulating purification technique, the prospects of amino acid additive development, self-adapting jet parameter supply system, matching mechanism between processing conditions and cutting fluid are put forward, which provides the basis and support for the engineering application and development of cutting fluid and its circulating purification. [ABSTRACT FROM AUTHOR]

Impurities are of crucial interest in optoelectronic devices as they affect carrier lifetimes and electrical properties. In view of that, it is important to incorporate certain processing steps to reduce impurities effect on final devices. The aim of this work is to enhance silicon carbide SiC purity for silicon passivation. Low cost method of SiC purification is presented. This method combines three main steps consisting of formation of porous silicon carbide layers by acid vapor etching followed by a photo-thermal annealing at different temperatures. Finally, obtained SiC powder was subject to a chemical treatment to remove porous SiC layer. Effect of gettering temperature on purification efficiency was evaluated by inductively coupled plasma atomic emission spectrometry (ICP-AES). The gettering experiment was performed at 800–950 °C, and optimum results were obtained at 950 °C. SiC purity is improved from 3 N (99.977%) to 5 N (99.999%) with an impurity removal efficiency of 96.56%. Purified SiC was used as a target to synthesize SiC layers using pulsed laser deposition technique (PLD) for optoelectronic devices. The use of intrinsic amorphous silicon carbide (a-SiC) passivating layers was investigated especially by photoconductivity decay technique. Improved SiC target purity leads to a significant enhancement of a-SiC passivating properties attributed to the surface recombination velocity decrease. Electrical properties of a-SiC/c-Si(p) were also studied using I-V and C-V techniques. [ABSTRACT FROM AUTHOR]

Due to widespread droughts and population increase, the rapid and sustainable purification of contaminated water is of major interest to human beings. Toward this end, this paper reports a handheld and efficient purification system using maskless micro/nanofabrication techniques. A porous polymer membrane decorated with nanomaterials was tailored to physically filter pollutants in contaminated water. To create the porous polymer membrane, curable polymer and black sugar powder were used for a facile and cost-effective fabrication method. The black sugar particles linked in cured polymer were selectively dissolved in hot water, forming micro-sized pores for filtering out pollutants. The nanowires were hydrothermally grown onto the porous membrane to further improve the purification performance by capturing finer pollutants between nanowires. The combination of nanowires and 50-wt% concentration of black sugar particle, forming a porosity of ~ 27.71% showed the minimum residual rate (i.e., weight of pollutants in purified water) of 0.981 mg/ml. This study supports the use of hierarchical porous membrane for the efficient and sustainable purification of contaminated water within a short period time. [ABSTRACT FROM AUTHOR]