Hi-tech Researches Speed up Scientific and Technological Innovations of CNOOC

The scientific and technological development of CNOOC Limited entered a new stage during the Tenth Five-Year Plan period. High-tech researches in the company have catalyzed the technological innovation of the offshore petroleum industry. By undertaking 11 key projects concerning key technologies for exploration and development of giant Bohai oil field under China＇s National 863 Program, 24 sub-projects of CNOOC＇s projects matching with China＇s National 863 Program, and 10 sub-projects of National Key S ＆ T Special Projects through cooperation with Chinese Academy of Sciences, the company developed 10 technology series with intellectual property rights.     

Enhancement of organoclay on thermal and flame retardant properties of polystyrene/magnesium hydroxide composite

Organoclay (organically modified montmorillonite, OMMT) was introduced to the composite of polystyrene/magnesium hydroxide (PS/MH) by melt compounding. The structure of the obtained PS/MH/OMMT composite was characterized by X‐ray diffraction and transmission electron microscopy. Thermal degradation behavior and flame retardancy of the composite were investigated by various means. It is shown that the PS/MH/OMMT composite has an intercalated nanostructure with the PS chains intercalated between the OMMT layers and the MH particles dispersed evenly in the PS matrix. Compared with the PS/MH composite containing identical amount of flame retardant, the introduction of OMMT has increased the thermal degradation temperature and lowered the mass loss rate at high temperatures. The PS/MH/OMMT nanocomposite can produce a more continuous and compact charred residue layer upon degradation both in air and burnt in flame than the PS/MH composite. Because of formation of this highly thermally stable and insulating charred residue layer, the nanocomposite exhibits much improved thermal endurance, flame retardancy, smoke suppression, and dripping resistance. Moreover, the combination of MH and OMMT makes the composite more difficult to ignite and decreases the release of toxic gas. The advantage of the PS/MH/OMMT nanocomposite is more pronounced in the early stage of combustion. POLYM. COMPOS., 37:746–755, 2016. © 2014 Society of Plastics Engineers     

扇形铅黏弹性阻尼器综合设计及加固框架抗震性能分析

为研究扇形铅黏弹性阻尼器与加固框架结构之间的匹配关系及其对加固框架抗震性能的影响规律,用ABAQUS软件建立了对比空框架和加固框架的精细化有限元模型,结合试验试件骨架曲线及破坏形态验证了其合理性。提出扇形铅黏弹性阻尼器加固框架的综合设计原则,设定阻尼器扇形有效半径与框架柱净高之比为设计尺寸比,在此基础上,对不同设计尺寸比的加固框架进行对比分析。分析结果表明,合理设置的扇形铅黏弹性阻尼器可以显著提高加固框架的抗震性能,保护梁柱节点核心区;当设计尺寸比取值超过0.24时,会导致加固试件较早达到峰值荷载,但其后承载力又急剧衰减;建议扇形铅黏弹性阻尼器加固框架的设计尺寸比宜控制在0.1~0.2之间,实际设计中应依据不同加固需求选取相应的设计尺寸比。     

A6N01铝合金焊接接头疲劳损伤和断口形貌分析

采用高频疲劳试验机对A6N01铝合金MIG焊接试样进行低周拉伸疲劳试验,研究了A6N01铝合金焊接接头疲劳过程中表面形貌变化和疲劳断裂后的断口形貌。结果表明:随着循环应力的加载,在试样产生裂纹之前,晶界处位错塞积严重,产生永久滑移带,裂纹源萌生于永久滑移带。气孔、夹杂等缺陷处应力集中较大,也容易称为裂纹源。在裂纹扩展过程中,主裂纹对次裂纹的扩展具有屏蔽作用。裂纹在相邻的不同位向的晶粒中扩展时,裂纹扩展方向发生变化。A6N01铝合金焊接接头疲劳断口有较多浅显的韧窝,说明A6N01铝合金焊接接头具有良好塑性。     

振动测试中低频失真放大问题的机理

针对振动环境试验和振动测量中低频失真放大现象的机理问题,应用MATLAB软件进行分析和仿真,在典型随机信号上叠加低频正弦信号或脉冲信号,复现了低频失真放大现象。通过试验对低频失真的物理机理进行了研究。分析和试验结果表明,测量信号中超低频成分与特定的谱分析方法共同作用,是出现低频失真放大的直接原因。测量电路虚接、电路连接松脱、测量超出传感器量程、被测结构或传感器松动、特殊结构单向脉冲等情况,是产生超低频信号并间接导致低频失真的物理原因。仿真与试验结果一致,证实了振动测试低频失真放大的机理。对该机理的认识有助于减少相关振动测量问题。     

官地地下尾水岔洞开挖与衬砌稳定研究

水利工程中地下大跨度尾水岔洞往往在结合交叉处形成复杂的三维空间结构,该部位受力性质复杂,位移较大,应力集中,一般需对其进行精细的三维数值模拟,分析开挖与衬砌结构的稳定性。文章利用FLAC3D,计算分析了官地水电站尾水岔洞围岩在开挖情况下的变形、应力及屈服区,对不同应力释放荷载条件下的喷锚支护效果及机理进行了分析评价;在此基础上根据运行和检修工况下的荷载作用情况,计算分析了衬砌结构应力,以及围岩锚杆的受力状态。指出控制作用工况,提出了保持岔洞稳定的措施和对策。计算分析表明:围岩开挖变形量较大,顶拱最大下沉约23 mm,边墙应力释放明显,最大拉应力约3.8 MPa,衬砌最大拉应力在2.0-2.6 MPa之间,岔角处岩体塑性区局部贯通,设计喷锚支护措施处于正常承载状态,支护措施能够满足围岩稳定性要求。计算分析得出的结论已用于指导工程设计,同时也可供其他同类工程的设计和施工参考。     

Surface modified bacterial biosorbent with poly(allylamine hydrochloride): Development using response surface methodology and use for recovery of hexachloroplatinate(IV) from aqueous solution

In this study, poly(allylamine hydrochloride) (PAA/HCl) was cross-linked with fermentation bacterial waste (Escherichia coli) in order to introduce a large amount of amine groups as binding sites for potassium hexachloroplatinate(IV), as a model anionic pollutant. The sorption performance of PAA/HCl-modified E. coli was greatly affected by the dosages of PAA/HCl and crosslinker (epichlorohydrin, ECH), and by the pH of the modification reaction medium. These factors were optimized through the response surface methodology (RSM). A three-level factorial Box-Behnken design was performed, and a second-order polynomial model was successfully used to describe the effects of PAA/HCl, ECH and the pH on the Pt(IV) uptake (R² = 0.988). The optimal conditions that were obtained from the RSM were 0.49 g of PAA/HCl, 0.05 mL of ECH and pH 10.02, with 1.0 g of dried E. coli biomass. The biosorption isotherm and kinetics studies were carried out in order to evaluate the sorption potential of the PAA/HCl-modified E. coli that was prepared under the optimized conditions. The sorption performance of the developed bacterial biosorbent was 4.36 times greater than that of the raw E. coli. Desorption was carried out using 0.05 M acidified thiourea and the biosorbent was successfully regenerated and reused up to four cycles. Therefore, this simple and cost-effective method suggested here is a useful modification tool for the development of high performance biosorbents for the recovery of anionic precious metals.     

放电等离子烧结工艺对ZrB_2-YAG陶瓷力学性能的影响

ZrB2具有优良的物理特性和化学稳定性而应用于许多领域,但是ZrB2难以烧结致密和在高温条件下容易被氧化.为了充分发挥ZrB2的优点,改善ZrB2的缺点,本文采用共沉淀法制备壳核式Al2O3-Y2O3/ZrB2复合粉体,通过放电等离子烧结法制备高致密的ZrB2-YAG陶瓷.研究结果表明:烧结温度由1300℃到1700℃时,陶瓷杨氏模量和断裂韧性都增大;在20MPa前,陶瓷杨氏模量和断裂韧性随着烧结压力增大而逐渐增大;在保温时间小于4min,陶瓷的杨氏模量和断裂韧性随着保温时间的延长而增大.     

分散剂对二硼化锆粉体分散稳定性的影响

通过共沉淀法获得包覆式Al2O3-Y2O3/ZrB2复合粉体并对其进行放电等离子烧结来改善ZrB2陶瓷的烧结致密度和高温抗氧化能力.为了得到很好的包覆效果,在包覆过程中,必须使得ZrB2粉体颗粒具有较好的分散稳定性.主要研究分散剂对二硼化锆粉体在水溶液中的分散稳定性影响.通过研究表明:分散剂为聚甲基丙烯酸铵(PMAA),并且当它的含量为2vol%时可以得到分散稳定性较好的二硼化锆溶浆,为改善合成更好包覆效果的包覆式Al2O3-Y2O3/ZrB2复合粉体奠定基础.     

Improvement of the surface quality of foam injection molded products from a material property perspective

Microcellular injection molding is an attractive method. However, their surface imperfections have been a major problem hindering wide industrial applications. Several methods have been proposed to improve the surface appearance of foams. In this study, we proposed a method to improve the surface appearance of polypropylene (PP) foams from the material property perspective, especially with regard to crystallization and viscosity. The basic idea of the surface improvement is to reduce the size of bubbles generated at the flow front, delay the solidification behavior of the polymer at the mold interface, squeeze the bubbles existing at the mold–polymer interface, and redissolve the bubbles into the polymer by holding pressure. Blending a low-modulus PP delays the crystallization of the polymers at the skin layer and solidification, taking enough time to squeeze the bubbles smaller. A sorbitol-based gelling agent, bis-O-([4 methylphenyl]methylene)-D-Glucitol, was used to increase the viscosity at a low strain rate to reduce the size of the bubbles generated at the flow front during the filling stage. The foam injection molding experiments demonstrated that the proposed method effectively improved the surface appearance of the foams. In particular, the surface appearance of the foams became almost equivalent to that of solid samples using low-modulus PP.