Magnetically rotational reactor for absorbing benzene emissions by ionic liquids

A magnetically rotational reactor （MRR） has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/g higher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet.     

Ultrasonic flexural vibration assisted chemical mechanical polishing for sapphire substrate

The sapphire substrates are polished by traditional chemical mechanical polishing (CMP) and ultrasonic flexural vibration (UFV) assisted CMP (UFV-CMP) respectively with different pressures. UFV-CMP combines the functions of traditional CMP and ultrasonic machining (USM) and has special characteristics, which is that ultrasonic vibrations of the rotating polishing head are in both horizontal and vertical directions. The material removal rates (MRRs) and the polished surface morphology of CMP and UFV-CMP are compared. The MRR of UFV-CMP is two times larger than that of traditional CMP. The surface roughness (root mean square, RMS) of the polished sapphire substrate of UFV-CMP is 0.83 Å measured by the atomic force microscopy (AFM), which is much better than 2.12 Å obtained using the traditional CMP. And the surface flatness of UFV-CMP is 0.12 μm, which is also better than 0.23 μm of the traditional CMP. The results show that UFV-CMP is able to improve the MRR and finished surface quality of the sapphire substrates greatly. The material removal and surface polishing mechanisms of sapphire in UFV-CMP are discussed too.     

Chemical Analysis and Toxicity Tests of Organic Pollutants in Xi River Water and Suspended Sediment of Shenyang City

Abstract

In 1987, in a 10-day investigation, two kinds of raw water and their suspended sediment samples were successively collected from the upper and middle reaches of the Xi River. The water and the suspended sediment samples were prepared by filtration of the raw water through a 0.45 μm membrane. The pH values of the water samples were adjusted to neutral (pH 6.5), basic (pH 11.0) and acid (pH 2.0) and passed through three adsorption columns filled with GDX macroreticular resin (MRR). The organic pollutants were subsequently eluted from the columns with CH₂Cl₂. Suspended sediment samples were extracted with CH₂Cl₂ by Soxhlet extraction. Organic pollutants were separated on silica gel columns and analyzed by GC and GCMS and assayed for acute toxicity, Ames test response, and micronucleus test response. Over 200 organic pollutants in the river water and the suspended sediments were determined. More than 60 main pollutants were identified according to the results of the chemical analysis and toxicity tests.     

螺旋锥齿轮超声研磨的试验研究

介绍了螺旋锥齿轮超声研磨加工的方法,利用声学和超声空化的相关理论分析了超声研齿的材料去除方式,在齿面接触区具有旋转超声加工的特点,在非接触区,超声空化对齿面产生空蚀或者直接激励磨粒撞击和滑擦齿面,引起材料的去除。进行了超声研齿和普通研齿的对比试验,结果表明超声研齿的材料去除率可达到普通研磨的3倍,齿面粗糙度低至Ra0.2μm,水平截距c1.2μm。齿面研磨后的SEM照片证实,齿面质量明显提高。     

Effect of additives for higher removal rate in lithium niobate chemical mechanical planarization

High roughness and a greater number of defects were created by lithium niobate (LN; LiNbO₃) processes such as traditional grinding and mechanical polishing (MP), should be decreased for manufacturing LN device. Therefore, an alternative process for gaining defect-free and smooth surface is needed. Chemical mechanical planarization (CMP) is suitable method in the LN process because it uses a combination approach consisting of chemical and mechanical effects. First of all, we investigated the LN CMP process using commercial slurry by changing various process conditions such as down pressure and relative velocity. However, the LN CMP process time using commercial slurry was long to gain a smooth surface because of lower material removal rate (MRR). So, to improve the material removal rate (MRR), the effects of additives such as oxidizer (hydrogen peroxide; H₂O₂) and complexing agent (citric acid; C₆H₈O₇) in a potassium hydroxide (KOH) based slurry, were investigated. The manufactured slurry consisting of H₂O₂-citric acid in the KOH based slurry shows that the MRR of the H₂O₂ at 2 wt% and the citric acid at 0.06 M was higher than the MRR for other conditions.