稀土对45钢表面渗锆及渗层组织性能的影响

本文首次报道了用气相法对４５钢表面渗锆。与以往不同的是,利用了稀土的活化催渗作用使渗锆过程在较低的温度和较短的时间内进行。通过扫描电镜、光电子能谱、Ｘ射线衍射分析证实了锆渗入金属表层并形成新相。对共渗后渗层组织和性能进行研究,结果表明：在稀土作用下锆渗入４５钢表层后强化了钢的表面,洛氏硬度ＨＲＣ高达６７,显微硬度也明显提高     

聚酰亚胺／磺化聚芳醚砜共混中空纤维膜用于醇／醚气相分离的研究

甲醇／ 甲基叔丁基醚的分离是目前具有实用意义的重要研究课题之一．文中采用气流吹扫式操作,研究了不同共混比的磺化聚芳醚砜／ 聚酰亚胺中空纤维膜对甲醇／ 甲基叔丁基醚气相混合体系的分离性能,以及不同操作条件对分离性能的影响．结果表明,共混改性聚酰亚胺膜具有非常高的醇／ 醚分离系数,有很好的应用前景．     

高温凝胶色谱测定药用低密度聚乙烯的相对分子质量

目的 建立准确测定药用低密度聚乙烯（聚乙烯瓶）相对分子质量信息的高温凝胶色谱方法。方法 供试品于150 ℃下震荡溶解2 h,流动相为1,2,4,-三氯苯（含250 mg/L的抗氧剂BHT）,色谱柱为高度交联的多孔聚苯乙烯/二乙烯基苯基柱,流速为1 mL/min,进样量为200 μL,柱温为150 ℃,运行时间为35 min。考察溶解温度、溶解时间以及抗氧剂对相对分子质量测定的影响,并对方法进行优化,对不同的相对分子质量测定方法进行比较。结果 对优化后的方法进行方法学考察,并采用相对法和绝对法计算相对分子质量。采用相对法计算出3批供试品的相对分子质量分别为236 327,238 832,240 631,相对分子质量分布分别为3.42,3.48,3.66;采用绝对法计算得到的相对分子质量分别为184 158,186 674,184 006,相对分子质量分布分别为4.30,4.25,4.24。结论 该方法可准确测定药用低密度聚乙烯的相对分子质量信息。     

P型沸石膜的合成及表征

采用水热合成法,详细考察了凝胶碱度对P沸石及其膜的合成的影响,发现凝胶碱度变化对合成晶化产物结构具有决定性影响,确定在实验条件下最佳合成碱度为Na2O/H2O=0.0163~ 0.0212. 在长250 mm、平均孔径3~5 mm的a-Al2O3陶瓷管外表面经二次涂膜,直接原位合成出膜厚约10~12 mm的沸石膜;XRD, SEM及H2, N2单组分气体渗透表征测试表明,载体管上的晶粒均匀规整,互锁状生长,为典型的P型沸石膜, H2和N2在膜内外压差为60~60 kPa范围内(25oC时),渗透速率分别为(3.60~3.99)10-6和(1.13~1.24)10-6 mol/(sm2Pa),同时具有较好的H2/N2选择系数(3.19~3.33).     

Stabilized bismuth oxide–noble metal mixed conducting composites as high temperature oxygen separation membranes

Oxygen concentration cells, with dense dual phase composite membranes made from erbia-stabilized bismuth oxide and a noble metal (Au, Ag), were investigated in the temperature range 650–850°C under controlled oxygen partial pressure gradients. An electrochemical treatment was applied to interpretation of the oxygen permeation data. It is found that the composite membranes exhibit high oxygen permeability relative to the single phase bismuth oxide, since oxygen ions and electrons are allowed to transport through the oxide and metal phase, respectively. The oxygen permeability of the silver-containing composite is at least one order higher than that of the gold-containing one, which can be explained by the fact that silver has a higher catalytic activity than gold for the surface oxygen exchange reaction and thus less limitations are exerted on the overall oxygen transport.     

Estimation of permeation rate of chemicals through elastometric materials

Elastometric materials are used as barriers to protect workers against exposure to chemicals. The effectiveness of a polymer as a chemical protective material therefore depends on the rate of the permeation of chemicals through it. The permeation rate depends on the solubility and the diffusion coefficient of chemicals in the materials. The diffusion coefficient itself is a strong function of concentration of the chemicals in the polymeric material. Permeation rates can be measured directly using a permeation cell or they can be calculated from the solubility and the diffusion coefficient data. Sorption/desorption experiments can be used to determine solubility and an expression for the diffusion coefficient in terms of concentration. Experiments were conducted for the sorption and desorption of ethyl acetate in three glove (one butyl and two neoprene materials) and two garment (neoprene and chlorinated polyethylene) materials. The data collected were used to estimate the steady‐state permeation rates of ethyl acetate through the materials. The results of the experiments show that the solubility of ethyl acetate in butyl rubber is 0.795 g/cm³, and the steady‐state permeation rate is 0.32 μg cm⁻² s⁻¹. The solubility of the chemical through the three neoprene materials is in the range of 2.25–5.31 g/cm³, and the steady‐state permeation rates vary from 27 to 43 μg cm⁻² s⁻¹. The solubility of ethyl acetate in the chlorinated polyethylene is 7.14 g/cm³, and the steady‐state permeation rate is 62.43 μg cm⁻² s⁻¹. The experimental method is very simple to use and it requires a small sample of the material (less than 1 cm²) and only a few milliliters of the chemical. Sorption/desorption experiments can also provide information on the amount of additives extracted from an elastomeric material during contact with a chemical. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1265–1272, 2001     

微孔膜的可压缩性及参数变化对膜蒸馏跨膜传质速率的影响

针对两种聚四氟乙烯膜在膜两侧压差为10～100kPa范围内进行了气体渗透实验,结果表明：实验用膜具有一定的可压缩性,随膜两侧压差的增大,膜孔径r减小,而膜孔隙率与有效厚度的比值ε／τδ是增大的,且其变化幅度随膜厚度的增大而增大,通过求解数学模型方程得到了不同膜参数时直接接触式膜蒸馏和真空膜蒸馏跨膜传质速率的预测值,与相同条件下的膜蒸馏实验测定的传质速率进行对比,结果表明：由膜的可压缩性带来的膜参数变化能够使跨膜传质速率有所增长,采用相近压差下气体渗透实验测定的膜参数能够较准确地预测膜蒸馏的跨膜传质速率。     

氮-甲醇保护气氛对45CrNiMoVA高强钢氢致断裂的影响

采用化学成分分析、断口形貌分析、显微组织分析、力学性能测试等方法对断裂后的45CrNiMoVA钢制高强扭杆进行了分析,并开展了氮-甲醇保护气氛下零件表面氢含量的测定,探讨了氢致缺陷对高强钢零件扭转疲劳的影响机理,提出了防止渗氢的预防措施,并进行了试验验证。结果表明,在氮-甲醇保护气氛下进行高强钢加热可导致氢的侵入,产生氢脆现象,影响高强钢零件扭转疲劳寿命。将氮-甲醇可控气氛更改为氮气保护,配合花键部位人工涂刷防脱碳涂料可有效防止表面氧化脱碳。采用改进工艺,高强钢扭杆未发生断裂现象。     

Radiation-induced graft copolymerization of 2-hydroxyethyl methacrylate onto chloroprene rubber membrane. II. Characterization of grafting copolymer

The cobalt-60 radiation-induced graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto a chloroprene rubber (CR) membrane has been studied in ethanol. The structure, morphology, crystallinity, thermal stability, and hydrophility of graft copolymer were characterized by means of Fourier transform infrared photoacoustic spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, differential thermal gravimetric analysis, and contact angle test methods, respectively. The permeabilities of urea, creatinine, and creatine through the CR and CR-g-HEMA membranes are investigated in a dialysis cell, and the permeation mechanism is also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1745–1750, 1998     

Preparation and properties of polybenzidine film-coated electrode as an H2O2 selective polymeric material

By means of electrochemical polymerization, polybenzidine-modified electrodes were prepared in an aqueous monomer solution at a potential of 0.7 V versus Ag/AgCl. The permselective character of the polybenzidine electrode prepared in a one-step procedure was examined for electroactive (ascorbic acid, oxalic acid, and hydrogen peroxide) and nonelectroactive (lactose, sucrose, and urea) species. Influence of the various parameters on the permselective properties of the polybenzidine membrane was systematically investigated and the optimal values for these parameters were determined. It has been found that polybenzidine membrane showed selective permeation for hydrogen peroxide while blocking the permeation of electroactive and nonelectroactive interferents through film. In brief, it is claimed that this polybenzidine film can be used as a coating material to prevent interferences in electrochemical biosensor applications. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2227–2234, 1998