微米级空间碎片撞击太阳电池研究

目的评估航天器太阳电池阵遭遇微米级空间碎片撞击后性能的下降程度。方法利用激光驱动飞片发射系统针对硅太阳电池开展系统的试验工作,对太阳电池机械损伤特性及伏安特性进行测试。利用ORDEM2000软件计算航天器所在轨道的碎片通量和速度。结合试验结果,计算航天器太阳电池阵因微米级空间碎片撞击引起的最大输出功率衰减率。结果太阳电池最大输出功率衰减率与溅射区直径呈二次函数关系,与表面污染率近似相等。未来5年天宫一号所在轨道航天器太阳电池因微米级空间碎片撞击引起的最大输出功率衰减率为0.45%。结论利用该研究结果可以预计航天器太阳电池因微米级空间碎片撞击引起的最大输出功率衰减率,为航天器总体设计提供技术支持。     

C/C-SiC-ZrB2复合材料表面SiC/ZrB2-SiC/SiC涂层的制备及抗氧化烧蚀性能研究

目的研究C/C-SiC-ZrB_2复合材料表面SiC/ZrB_2-SiC/SiC涂层的制备、抗氧化烧蚀性能与机理。方法选择ZrB_2和SiC改性的C/C复合材料为基体,通过包埋-刷涂法在C/C-SiC-ZrB_2复合材料表面制备了SiC/ZrB_2-SiC/SiC多重抗氧化涂层,并对复合材料的微结构、抗氧化烧蚀性能与机理进行分析和研究。结果制备了一种三层结构的SiC/ZrB_2-SiC/SiC超高温陶瓷复合涂层,获得了风洞考核试验下的复合材料微结构变化、线烧蚀率等试验数据,并得到了C/C-SiC-ZrB_2复合材料的氧化烧蚀机理。结论 SiC/ZrB_2-SiC/SiC涂层对C/C-SiC-ZrB_2复合材料的抗氧化和耐烧蚀性能具有明显提升,有效提高了C/C-SiC-ZrB_2复合材料的综合热防护性能。     

轻质Cf/SiOC复合材料表面抗氧化涂层烧蚀性能的研究

目的提高轻质碳纤维增强SiOC(C_f/SiOC)多孔陶瓷复合材料的抗烧蚀性能。方法用TaSi_2、MoSi_2为高温抗氧化组分,SiB_6为烧结助剂,硼硅酸玻璃为粘结剂,采用浆料法在C_f/SiOC复合材料表面制备多层梯度化抗氧化涂层。用氧乙炔考核带涂层复合材料的抗氧化及抗烧蚀性能,并通过扫描电子显微镜对烧蚀后的形貌进行分析。结果采用硼硅酸玻璃能够在较低的温度下获得表面致密的涂层,有效地提升涂层的阻氧能力,同时能够降低涂层与基体材料之间的热失配。通过浆料法能够获得梯度化的抗氧化涂层,即涂层由靠近基体部分的多孔层逐渐过渡至最外层的致密层。在氧乙炔考核烧蚀实验下,涂层表现出优良的抗烧蚀性能,并且随着表面烧蚀温度的不同,表现出不同的烧蚀行为。在1660℃下烧蚀后,线烧蚀率及质量烧蚀率分别为0.03μm/s,2.96×10-8g/(mm2·s),随着烧蚀温度增加至1760℃,线烧蚀率及质量烧蚀率增加至0.06μm/s,1.03×10-7g/(mm2·s)。带涂层的复合材料烧蚀后,涂层表面没有裂纹,但都出现了大量的孔洞,其主要原因是硼硅酸玻璃的挥发,基体材料并没有发生明显的氧化,涂层表现出优良的抗氧化、阻氧能力。结论硼硅酸玻璃的引入能够在较低的温度下获得表面致密的涂层,提升涂层的阻氧能力。制备的多组分抗氧化烧蚀涂层,可以有效地提高C_f/SiOC复合材料的抗烧蚀能力。     

铌合金表面热防护涂层研究进展

作为武器装备、航空航天等多种现代工业领域热端部件中应用十分广泛的结构材料,铌合金在高温富氧燃流的冲刷下会发生严重的烧蚀现象,进而影响了其在超高温环境下的使用性能。研究发现,采用表面涂层技术能够有效提升铌合金的高温抗烧蚀性能。因此结合热端部件富氧、超高温的实际服役环境,首先介绍了国内外铌合金表面抗氧化烧蚀涂层领域的研究现状,对比分析了金属基和硅系陶瓷抗烧蚀涂层各自在抗氧化烧蚀性能上的优缺点;然后综述了近年来国内外有关热障涂层的研究进展,归纳总结了ZrO2基陶瓷涂层、稀土锆酸盐陶瓷涂层以及钙钛矿结构陶瓷涂层三种热障涂层材料的特点;最后对铌合金表面热防护涂层的结构设计以及未来的研究方向进行了展望。     

飞机结构表面涂层体系改进研究

针对多型飞机表面涂层体系抗腐蚀性能差这一亟待解决的问题,采用制造状态、大修状态及纳米复合涂层对设计的典型飞机蒙皮对接结构模拟件进行涂装,并利用划格法对涂层体系的层间附着力进行表征。采用加速模拟环境试验的方法,对纳米复合涂层的防腐性能进行考核验证。试验结果表明,纳米复合涂层体系的层间附着力、防腐性能和耐老化性能明显优于制造状态、大修状态涂层体系,在飞机中应用纳米复合涂层可以显著改善结构的抗腐蚀品质。     

Al2O3/Ni-P-SiC复合涂层组织与性能的研究

目的 采用化学复合镀技术对微弧氧化进行封孔,进而得到抗烧蚀性能优良的Al2O3/Ni-P-SiC复合涂层。方法 通过采用扫描电镜(SEM)、光学金相显微镜(OM)、显微硬度仪(Microhardness Tester)、X射线衍射仪(XRD)、氧–乙炔烧蚀试验(Oxy-Acetylene Ablation Test)等方法,对复合涂层的表面形貌、截面形貌、厚度、显微硬度、物相和抗烧蚀性能等进行分析。结果 陶瓷层原始表面完全被化学镀层覆盖,所制得的复合涂层厚度均匀,化学镀层与陶瓷层紧密嵌合。镀液中的SiC浓度对镀覆的速度、镀层中SiC粒子的共沉积量有着较大的影响。当粒子质量浓度为16~20 g/L时,颗粒的共沉积量较大。化学复合镀60 min可以得到厚度20 μm左右的Ni-P-SiC镀层,SiC颗粒分布均匀。当镀液中SiC质量浓度为16 g/L时,镀层具有最高的硬度。对比未处理、仅微弧氧化和Al2O3/Ni-P-SiC复合涂层试样,Al2O3/Ni-P-SiC复合涂层试样具有最佳的抗烧蚀性能。结论 Al2O3/Ni-P-SiC复合涂层均匀、致密,具有良好的抗烧蚀。     

火箭整流罩抗碎片侵彻能力的数值模拟

为研究火箭整流罩对箭上有效载荷的防护性能,以某型液体运载火箭为分析对象,利用Autodyn软件对火箭爆炸碎片撞击有效载荷整流罩的过程进行了数值模拟,分析了碎片撞击速度和撞击倾角对整流罩抗碎片侵彻能力的影响。数值计算结果表明:碎片的撞击速度和撞击倾角是影响火箭整流罩抗碎片侵彻能力的重要因素,对碎片本身形变也有一定的影响;侵彻时间随碎片撞击速度呈单调递减,当碎片撞击速度较小时,碎片撞击造成的速度损失与撞击速度呈正相关;有效载荷整流罩抗侵彻能力随碎片撞击倾角的增大而增强,侵彻时间随碎片撞击倾角的增大呈单调递增。数值模拟结果与理论计算结果基本吻合,表明该数值计算模型能较好地模拟火箭爆炸碎片撞击有效载荷整流罩的过程。     

濒海环境钢质紧固件防腐技术试验对比研究

目的针对某濒南海大型工程钢质紧固件腐蚀严重的问题,通过试验研究对比钢质紧固件的腐蚀防护技术。方法分别在钢质紧固件表面制备防护层膜,通过现场挂样试验和实验室环境模拟加速试验研究不同涂层的腐蚀行为,并采用电化学试验研究不同涂层在模拟条件下的失效机理。结果对现场试验、实验室加速试验和电化学阻抗测试数据进行分析,不同涂层紧固件的防腐效果排序为复合涂层锌铝涂层粉末渗锌≈热浸镀锌电镀锌氧化膜层保护。结论通过试验对比评价了紧固件6种表面处理技术的防腐性能,为濒海设备使用的紧固件防腐措施的选择提供了理论依据和技术支撑。     

身管内膛镀铬性能检测研究

目的对内膛表面强化层性能进行定量评估,给后续镀铬层的优化及新型内膛表面强化层技术的优选提供试验方法。方法以成熟度最高、应用最广泛的内膛表面镀铬技术为依据,开展强化层检测研究,主要包括硬度、厚度及微观缺陷、结合性能、抗烧蚀性能、抗磨损性能等研究。量化镀铬层抗烧蚀、抗磨损性能,实现实验室对内膛镀铬层性能的综合评估。结果铬层硬度约为521.8HV,高于基体硬度。铬层裂纹初始宽度约为300 nm,多数裂纹未连接成“网状”。铬层与基体结合力约为67.2 N。相同条件下,相比基体,镀铬层的烧蚀量和磨损量始终较小。结论镀铬层综合性能优于基体材料。     

硼化物基超高温复合陶瓷超高速撞击作用下破坏模式研究

随着各国航天实验和航天器的增加,太空中存在微小碎片垃圾越来越多,对航天器正常运行有着极大的危害。研究弹丸超高速撞击硼化物基复合陶瓷产生的碎片云特性,采用非线性动力学分析软件AUTODYN,利用光滑质点动力学方法对圆柱形弹丸超高速撞击硼化物基超高温复合陶瓷单层板形成的碎片云进行数值模拟,分析相同质量不同速度弹丸撞击靶板的破坏模式,不同质量相同速度弹丸撞击靶板的破坏模式。结果表明在不同速度和质量弹丸撞击靶板的破坏模式中,穿孔半径变化规律为穿孔半径随着弹丸速度和质量的增大而增大。根据不同质量弹丸超高速撞击板靶的穿孔半径变化规律,得到弹丸撞击相同厚度靶板的击穿速度临界值。该结果可为航天器超高速撞击风险评估和防护设计提供了参考。     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.