SP700钛合金表面纳米孔结构制备

采用电化学阳极氧化法在SP700钛合金表面制备了纳米多孔结构膜。电解质为含F-离子和不含F-离子的乙二醇溶液体系。研究了低压条件下纳米多孔结构的形成机制。利用EG&GPARM273恒电位仪测量动态电势极化曲线和阳极极化曲线,利用场发射扫描电子显微镜(JSM-6700FESEM)初步表征了自组装纳米孔的形貌和尺寸。分析表明,纳米孔形成的临界电压为2V,F-离子影响着最终纳米孔的孔深和孔壁厚度,导致孔加深和孔壁的减薄。     

阳极氧化Ti_3SiC_2制备纳米孔阵列EI北大核心CSCD

以NH4F和乙二醇为电解液,采用阳极氧化法在Ti_3SiC_2表面制备纳米多孔结构,研究阳极氧化电压、电解液浓度和氧化时间对纳米多孔结构形成的影响。利用场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)和X射线光电子能谱(XPS)对纳米多孔结构进行表征。结果表明:孔径随着氧化电压的升高而增大,且延长氧化时间有利于制备孔径均匀的纳米孔;Ti_3SiC_2试样经阳极氧化后除含有Ti、Si、C元素外,还含有O元素,且以TiO_2的形态存在。     

SP700 钛合金的热处理 / 阳极氧化工艺研究

目的采用电化学阳极氧化法,在SP700钛合金的表面制备多孔结构的氧化膜。方法利用Autolab PGSTAT30型电化学工作站,采用三电极体系,辅助阴极为石墨电极,参比电极为饱和甘汞电极,工作电极为试样,测定试样的动态极化曲线和阳极氧化I-t曲线。利用扫描电子显微镜观察阳极氧化表面多孔氧化膜的微观形貌,分析热处理工艺、阳极氧化电压、电解液成分等参数对SP700钛合金阳极氧化行为的影响规律。结果钛合金材料经固溶时效处理后,α相和β相的相对含量发生了变化,从而使氧离子对电化学反应界面的内应力发生变化,使得表层氧化膜更加平整,耐腐蚀性提高。F-是阳极氧化膜上纳米孔形成的必要条件,随着F-浓度的增加,阳极氧化膜表面纳米孔的密集程度增加,孔径减小,氧化膜厚度增加。在一定范围内,随着阳极氧化电压的增大,氧化膜增厚,但电压过高会破坏氧化膜的稳定性。结论用电化学阳极氧化法处理钛合金表面,得到了多孔结构的氧化膜,获得了理想的耐腐蚀性能。固溶时效处理后,钛合金的耐腐蚀性提高。     

阳极氧化Ti_3SiC_2制备纳米孔阵列

以NH4F和乙二醇为电解液,采用阳极氧化法在Ti_3SiC_2表面制备纳米多孔结构,研究阳极氧化电压、电解液浓度和氧化时间对纳米多孔结构形成的影响。利用场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)和X射线光电子能谱(XPS)对纳米多孔结构进行表征。结果表明:孔径随着氧化电压的升高而增大,且延长氧化时间有利于制备孔径均匀的纳米孔;Ti_3SiC_2试样经阳极氧化后除含有Ti、Si、C元素外,还含有O元素,且以TiO_2的形态存在。     

影响共电沉积过程中纳米Cr、Al粒子复合量因素初探

在Ni与纳米Cr粒子或Al粒子共电沉积过程中,发现Ni镀层复合纳米Al粒子要比复合纳米Cr粒子容易.电化学测试表明:两种粒子在镀液中阴极极化行为不同,加入纳米Cr粒子后,极化曲线正向偏移,阴极极化降低.而加入纳米Al粒子后,极化曲线负向偏移,阴极极化增大.进一步用HREM对镀层中纳米粒子进行原子尺度观测,发现两者表面皆存在几个纳米厚的氧化膜层,提出了纳米粒子表面氧化膜半导体类型不同而引起粒子在镀液中吸附阳离子能力的强弱不同,是影响纳米粒子复合量的重要因素.     

纳米化对M38高温合金电化学腐蚀行为的影响

    通过动电位极化曲线和Mott-Schottky分析电化学方法,研究了M38合金纳米涂层在3.5% NaCl溶液中的电化学腐蚀行为.结果表明,在3.5% NaCl溶液中,纳米化虽然没有改变合金表面钝化膜的半导体类型(p型),但是改善了钝化膜的致密性,降低了钝化膜中的载流子密度,提高了钝化膜的稳定性,所以,M38纳米涂层更耐氯离子侵蚀.     

Fe-20Cr纳米涂层的电化学行为

利用磁控溅射技术在玻璃基体上制备了Fe-20Cr纳米晶涂层.分别测试了Fe-20Cr铸态和纳米晶涂层在含氯离子溶液(0.005 mol/L H2SO4 0.5 mol/L NaCl)与不含氯离子的溶液(0.005 mol/L H2SO4 0.25 mol/LNa2SO4)中的动电位极化曲线.结果表明,纳米化使材料的溶解速度增大,纳米晶涂层在两种溶液体系中均容易钝化;与铸态合金相比,纳米涂层的维钝电流增大两个数量级.在含氯离子溶液中,纳米晶涂层的维钝区间是铸态合金的两倍,耐局部腐蚀性能得到很大提高.利用电容测试技术和Mott-Schottky关系研究了Fe-20Cr铸态合金与纳米晶涂层分别在两种溶液中所形成钝化膜的半导体性能.结果表明铸态合金在不含氯离子的溶液中低电位下所形成的钝化膜为p型半导体,高电位下形成n型半导体,在含氯离子溶液中形成的钝化膜为p型半导体;而纳米晶涂层在两种溶液体系中形成的钝化膜均为n型半导体.钝化膜的结构类型的不同是导致Fe-20Cr纳米晶涂层与铸态合金具有不同电化学行为的主要原因.     

轧制纳米块体304不锈钢腐蚀行为的研究Ⅰ.钝化膜耐氯离子侵蚀能力

用深度轧制方法获得了块体纳米304不锈钢材料．通过动电位极化曲线和Mott-Schottky分析等电化学测试手段，探讨了轧制纳米块体304不锈钢与普通304不锈钢（304ss）在0．05mol／L H2SO4＋0．05mol／L NaCl溶液中钝化膜的耐Cl^-侵蚀性能．研究表明，深度轧制使304不锈钢组织内部形成高密度纳米尺度孪晶；纳米化表面可以形成致密的钝化膜，使其耐Cl^-侵蚀能力提高．对钝化膜半导体性能分析结果表明，轧制纳米块体不锈钢钝化膜中的载流子密度有所下降，这在一定程度上抑制了钝化膜的电化学反应历程，从而进一步提高了钝化膜的化学稳定性．     

TiO2纳米阵列超疏水膜的制备及耐腐蚀性能

采用阳极氧化法在纯钛表面制备TiO2纳米管阵列,使用六甲基二硅胺烷对TiO2纳米管阵列进行低表面能处理,得到超疏水表面．用接触角测量仪测定表面疏水性,采用SEM、EDS技术研究改性前后试样表面的形貌和元素组成,并利用极化曲线和电化学阻抗谱法研究了超疏水膜的耐腐蚀性能．结果表明,TiO2纳米管阵列经改性后超疏水效果明显,...     

轧制纳米块体304不锈钢腐蚀行为的研究Ⅱ钝化膜保护性能

采用动电位极化曲线和Mott-Schottky分析等电化学测试手段,探讨了轧制纳米块体304不锈钢与普通304不锈钢在0.05mol/L H2SO4＋0.05mol/L Na2SO4溶液中钝化膜的保护性能;运用点缺陷（PDM）模型,分析了不同电位下在0.05mol/L H2SO4＋0.25mol/L Na2SO4溶液中两种材料形成钝化膜的半导体性质,阐述了导致两种钝化膜保护性能差异的根本原因.结果表明：两种材料表面钝化膜都具有n型半导体特征,氧空穴作为主要的载流子参与钝化膜的形成和溶解过程;钝化膜中载流子密度与钝化膜的形成电位之间满足幂指数关系,载流子在两种材料表面的钝化膜中的扩散系数非常接近,说明两种钝化膜遵从相似的形成和溶解机制,但轧制纳米块体304不锈钢中的载流子密度小于普通304不锈钢钝化膜中的载流子密度,从而使其钝化膜具有更好的保护性.     

MH-Ni电池用新型镍纤维阳极材料的制备及性能

报道了可以代替泡沫镍作ＮＨ－Ｎｉ电池阳极骨和镍纤维毡的制备工艺,研究了镍纤维丝径,镍毡的单重对孔径尺寸,孔隙率,比表面积的影响,经过在氢气和氩气２种气氛中进行烧结,保证了镍毡的抗拉强度和延伸变形率,可以制备出性能优良的镍纤维毡。     

Effect of Pre-annealing on Sintering of Stainless Steel Fiber Felt

Stainless steel fiber felt is a class of unique porous metal materials. This study investigates the effect of pre-annealing on the sintering of stainless steel fiber felt through quantitative characterization of sintered joints based on synchrotron radiation experiments. The sintered joint size was found to follow a marked normal distribution in fiber felt samples sintered with and without pre-annealing. However, pre-annealing prior to sintering led to a significant reduction in the total number of sintered joints as well as a reduction in the percentage of large sintered joints. Consequently, fiber felt samples sintered with pre-annealing achieved less than half the tensile strength of those sintered without pre-annealing. Delamination through fracture of sintered joints was pronounced in fiber felt samples sintered with pre-annealing, while failure occurred mainly through fracture of individual fibers in those sintered without pre-annealing. It was concluded that sintering without pre-annealing is necessary for the fabrication of high-strength fiber felt products and the reasons are briefly discussed.     

Preparation of oriented linear copper fiber sintered felt and its performance

Long metal fibers were manufactured in horizontal lathe with a multi-tooth tool. Based on the coarse antler surface structure of copper fibers, a new sintering technology was put forward to manufacture a kind of oriented linear copper fiber sintered felt. The sintering mechanism of oriented linear copper fiber sintered felt was studied. Compared with sintered copper-wire felt, the characteristics of sintered copper-fiber felts were analyzed in details. Owing to the coarse antler surface structure of copper fibers, oriented linear copper-fiber felt was sintered under the condition ofmicro/nano scale range, and copper fibers easily bonded together in the sintering process. Microchannels with micro-scale coarse antler surface structure were constructed. These characters give oriented linear copper fiber felt some new merits： high filtration accuracy, high flow capability, low resistance loss, good capability to resistance pressure, stable and uniform pore, high specific surface area. The properties of oriented linear copper fiber sintered felt were analyzed.     

介质对金属滤毡初始气泡点压力的影响

依据国家标准,研究了介质类型和环境温度对滤毡初始气泡点压力的影响.实验结果表明,初始气泡点压力与试验选用的介质和环境温度有关,相同条件下,试验介质的密度和表面张力越大,滤毡的初始气泡点压力也就越大;环境温度越高,初始气泡点压力越低;且用95%乙醇测初始气泡点压力时所测结果受温度影响比异丙醇小.     

Effects of cold roll and heat treatments on anomalous thermal behavior in Fe100−xAlx(x = 5–30) alloys

DSC measurements were carried out for various Fe_100−xAl_x(x = 5–30 at%) alloys to clear the effects of cold roll and quenching rate from 1173 K. In the case of cold roll free specimens, an exothermic peak was observed at around 530–560 K in quenched specimens and no peaks in slowly cooled specimens. The peak temperature and its exothermic heat depended on the alloy composition. The maximum exothermic heat was obtained for a 25 at% Al alloy and its value were about 1200 J/mol. The peak in a 5 at% Al alloy was remained as a future work. The exothermic heat was affected by the quenching temperature in alloys above 15 at% Al. The peak temperature was decreased by decreasing the quenching temperature. In a 15 at% Al alloy, the peak became negligibly small by quenching from 1023 K. The activation energies in cold roll free specimens were evaluated from the Kissinger analysis and they were 134, 108, 133 and 110 kJ/mol for 15 at% Al, 20 at% Al, 25 at% Al and 30 at% Al alloys, respectively. On the other hand, cold rolled specimens showed an exothermic peak at around 470 K, independently of the cooling rate. Their exothermic heats and temperatures were comparable order to those of furnace cooled and water quenched specimens. The present results suggested that origin of exothermic peaks of all alloys were same in nature and atomic ordering may be related to the exothermic behavior at relatively low temperatures.     

The pitting corrosion of sputtered Fe base alloy films

Predominantly single phase Fe base alloy films were prepared by a DC sputtering method. The compositions of the alloy films, as determined by Auger electron spectroscopy (AES) were Fe-7 at% Cr and Fe-18 at% Cr, Fe-11 at% W and Fe-19 at% W, Fe-9, −13 and −27 at% Ta. The pitting potential of the sputtered alloys determined in chloride solutions was found to be strongly dependent on the nature and the concentration of the alloying element. The pitting potential of sputtered Fe-18 at% Cr and Fe-27 at% Ta alloy films were approximately 0.9 V higher than that of bulk Fe and 0.6 V higher than that of Fe-19 at% W alloy film. A very good correlation was found between the pitting potential of Fe alloy films and the solubility of an alloying element oxide in acidic solutions with a pH corresponding to that within the stable pits of pure Fe (pH = 2). The pitting potential of the Fe alloy was found to increase with a decrease in the solubility of the alloying element oxide in acidic solutions. The pitting potentials of the sputtered Fe-7 at% Cr and Fe-18 at% Cr alloy films were were significantly higher than those of the bulk materials with the same composition. The higher pitting potentials of these alloy films are tentatively attributed to the presence of very fine particles of the oxide phase that are homogeneously distributed in the sputtered alloys.     

不同预制体炭/炭复合材料在髋关节模拟试验机中的磨损颗粒表征(英文)

采用髋关节模拟试验机检测穿刺碳布预制体和碳毡预制体炭/炭复合材料的磨损行为。分离提取产生的磨损颗粒,检测颗粒形貌和尺寸分布并提出颗粒的演化过程。结果表明:炭/炭复合材料磨损颗粒的尺寸分布在亚微米至数十微米之间,颗粒形貌呈现破损纤维状、纤维碎片状、片状和球状。穿刺碳布预制体炭/炭复合材料比碳毡预制体炭/炭复合材料的磨损颗粒尺寸分布范围更广泛,磨损颗粒中的破损碳纤维状和片状形貌较多。热解碳颗粒的演变主要是其表面的规则化过程,而碳纤维颗粒的演变主要与髋关节模拟试验机提供的应力方向有关。     

纤维排布方式对KD-I/SiC复合材料性能的影响

采用国产KD-I型SiC纤维为增强体,通过先驱体转化工艺制备了SiC/SiC复合材料.研究了二维织物和针刺毡等纤维排布方式对复合材料显微结构和物理以及力学性能的影响.结果表明,与针刺毡增强SiC/SiC复合材料相比,2D SiC/SiC复合材料的纤维体积分数和密度较高、孔隙率低、所需制备时间短、成本低、面内性能好,但同时损失了Z向性能.在不同工况下应用的SiC/SiC复合材料应根据具体使用要求来选择纤维排布方式.     

Room-temperature solid solution softening in Fe-V binary system

Molecular dynamics simulations of the glide of an edge dislocation in the bcc matrix of Fe-V alloys were performed to investigate the room-temperature solid solution softening by V atoms. For this purpose, the glide velocity of an edge dislocation was calculated as a function of V concentration under the shear stresses of 100-300MPa using the Fe-V cross-potential constructed newly in the present study. Whereas the solid solution hardening occurred as the V concentration is less than 0.13 at% or more than 0.5 at%, the room-temperature solid solution softening was observed in Fe-(0.13-0.5) at% V alloys. The solid solution softening occurring in Fe-(0.13-0.5) at% V alloys was caused by the accelerated growth velocity of kinks by solute V atoms. The increase in kink velocity happened when the interatomic distance between solute V atoms was similar to the length of dislocation kinks.     

不锈钢纤维烧结毡在微生物燃料电池阳极中的研究进展

详细介绍了不锈钢纤维烧结毡在微生物燃料电池阳极中的应用现状及前景.不锈钢纤维烧结毡是采用微米级的不锈钢纤维经无纺铺制、叠配、真空烧结而成.它是由不同丝径的纤维形成的一种三维金属多孔材料,具有机械强度高、渗透性能好、导电性好、吸附能力强、耐腐蚀、耐高温、易加工等优点,在高效微生物燃料电池阳极材料方面呈现出了巨大的应用价值...