共查询到17条相似文献,搜索用时 78 毫秒
1.
在室温添加丙烯基硫脲(ATU)的稀盐酸溶液中,对块体纳米晶工业纯铁(BNⅡ)和普通工业纯铁(CPⅡ)的电化学腐蚀行为进行了对比研究.结果表明:在空白室温1mol.L-1HCl中,BNⅡ的抗腐蚀能力比CPⅡ的强.当添加ATU,浸泡5min后,两种样品的EIS(电化学阻抗谱)均没有出现感抗弧.随着时间的延长,对于BNⅡ,EIS谱图上出现一Warburg阻抗.在浓度为100mg.L-1,进行动电位极化测试时,两种样品均出现阳极脱附现象,脱附电位Edes有明显差异.与CPⅡ相比,ATU对BNⅡ的缓蚀作用非常有限,甚至有促进其腐蚀的趋势. 相似文献
2.
块体纳米晶工业纯铁在盐酸溶液中的电化学腐蚀行为 总被引:1,自引:0,他引:1
通过静态失重试验,动电位极化曲线,电化学阻抗谱(EIS)实验,研究了块体纳米工业纯铁(BNIPI)和粗晶工业纯铁棒(CGPIR)在室温1mol/l盐酸溶液中的腐蚀行为.结果表明,BNIPI与CGPIR相比,开路腐蚀电位Ecorr正向移动114mV,平均腐蚀速度和腐蚀电流Icorr变小,极化电阻Rp增大为1.58倍.BNIPI抗盐酸的腐蚀能力与CGPIR相比,不但没有下降,相反有所增强.使用扫描电子显微镜(SEM)对静态腐蚀失重试样的形貌进行了观察,显示BNIPI上几乎没有点蚀坑出现. 相似文献
3.
Ti-48Al-8Cr-2Ag纳米晶涂层对TiAlNb合金腐蚀行为的影响 总被引:1,自引:0,他引:1
研究了磁控溅射的Ti-48Al-8Cr-2Ag(原子数分数,%)纳米晶涂层对Ti-46.5Al-5Nb合金腐蚀行为的影响.结果表明,在600~700℃盐水蒸气的协同作用下,TiAlCrAg涂层使TiAlNb合金腐蚀速率降低.Nb是TiAlNb合金在700℃盐水蒸气协同作用下生成致密TiO2膜的主要原因.氯化物侵蚀α2相,使TiAlNb合金在盐和水蒸气综合作用下加速腐蚀,TiAlCrAg涂层中较少的α2相以及Laves相中较高的Cr含量是腐蚀速率降低的主要原因. 相似文献
4.
5.
6.
综述了块体纳米材料大塑性变形(SPD)制备技术的工作原理及分类.SPD技术按材料的细化机制一般可分为大塑性扭转挤压法(SPTS)、等径角挤压法(ECAP)和多重锻压法(Multi-forging).重点讨论了SPTS和ECAP工艺的切变机制及其工艺参数,同时分析了这两种工艺的优缺点,并在此基础上提出了一些解决方案. 相似文献
7.
电沉积工艺参数对块体纳米晶镍硬度的影响 总被引:2,自引:0,他引:2
采用直流电沉积方法,通过改变特殊添加剂C7H4NO3SNa·2H2O浓度、电流密度、沉积液温度,制备出不同硬度的块体纳米晶镍覆层材料,利用高分辨透射电子显微镜(HRTEM)对沉积覆层材料的组织形貌进行分析,利用显微硬度计测量沉积层材料的显微硬度,对块体纳米晶镍硬度的变化规律进行分析.结果表明:通过改变工艺参数,可获得结构致密,组织均匀的块体纳米晶覆层材料.块体纳米晶镍的硬度随着添加剂C7H4NO3SNa·2H2O浓度的增加而增加;随电流密度的增加,呈现增加趋势,在700A·m-2至1100A·m-2范围内,基本保持不变;随着温度的增加而下降. 相似文献
8.
9.
采用放电等离子烧结技术制备了全致密镝纳米晶块体材料,研究晶粒尺寸对其结构和磁性的影响。显微组织分析发现,在573K和773K的烧结条件下,材料的平均晶粒尺寸分别为10nm和100nm左右,晶体结构分析发现,镝纳米晶块体是与原始粗晶镝一样的密排六方结构晶体,磁性能测试结果表明,随着平均晶粒尺寸的下降,样品的奈尔温度(T_N)逐渐降低,而居里温度(T_C)则先降低后升高,在5K温度和9T磁场下,平均晶粒尺寸10nm的镝块体材料比粗晶镝的磁化强度降低了3.35%,矫顽力则增加了3倍。 相似文献
10.
11.
Ali Volkan Akkaya 《Sadhana》2006,31(5):543-556
In this paper, we examine the performance of PID (proportional integral derivative) and fuzzy controllers on the angular velocity
of a hydrostatic transmission system by means of Matlab-Simulink. A very novel aspect is that it includes the analysis of
the effect of bulk modulus on system control. Simulation results demonstrates that bulk modulus should be considered as a
variable parameter to obtain a more realistic model. Additionally, a PID controller is insufficient in presence of variable
bulk modulus, whereas a fuzzy controller provides robust angular velocity control. 相似文献
12.
13.
14.
The influence of ferric iron in calcined nano-Mg/Al hydrotalcite on removal of Cr (VI) from aqueous solution was studied from aspects of structure characteristics, adsorption properties and mechanism discussions. The calcined hydrotalcites (CH-Mg/Al and CH-Mg/Al/Fe) were obtained by thermal decomposition of their corresponding precursors and characterized by XRD, TEM, pH(PZC) and FTIR. The adsorption properties were studied as a function of pH, initial Cr (VI) concentration and contact time. The results showed that the nature of adsorption is endothermic and spontaneous for both CH-Mg/Al and CH-Mg/Al/Fe, but the thermodynamic parameter value changes revealed the addition of Fe(3+) is disadvantage to adsorption process and the theoretical saturated adsorption capacity decreased by approximately 10.2mg/g at tested temperatures. The removal mechanism involved not only intercalation but adsorption on external surface of the layers and interlayer anion exchange for both CH-Mg/Al and CH-Mg/Al/Fe. Furthermore, the results also indicated that intercalation accounts for a large proportion during removal process whatever for CH-Mg/Al, or for CH-Mg/Al/Fe. Additionally, the replacement of Al(3+) by Fe(3+) in CH-Mg/Al led to the interlayer anion exchange more difficult. On the basis of the results, it is concluded that the existence of ferric iron in calcined Mg/Al hydrotalcite is unfavorable to removal of Cr (VI) from aqueous solution. 相似文献
15.
土壤中硫酸盐还原菌对1Crl3不锈钢腐蚀的影响 总被引:4,自引:0,他引:4
利用交流阻抗测试、扫描电镜观测、表面能谱分析、失重法以及微生物分析等方法,研究了硫酸盐还原菌(SRB)对在不同C1^-含量的土壤中的1Crl3不锈钢腐蚀的影响.结果表明:随着土壤中C1^-含量的增大,1Crl3不锈钢的腐蚀速率和最大点蚀深度随着土壤中C1^-含量的增加而增大,当C1^-的含量增大到1.0%时达到最大值.与灭菌土壤相比,在接菌土壤中1Crl3不锈钢腐蚀速率和最大点蚀深度大,说明硫酸盐还原菌和C1^-的共同作用增大了土壤中1Crl3不锈钢的点蚀敏感性.1Crl3不锈钢未发生点蚀时阻抗图谱表现为单容抗弧,发生点蚀时阻抗图谱表现为有两个时间常数的双容抗弧. 相似文献
16.
LiOH水溶液提高Zr-4合金腐蚀速率的机理 总被引:1,自引:0,他引:1
在不同水化学条件下的高压釜中研究了Zr-4合金在LiOH水溶液中的耐腐蚀性能.结果表明,不同的腐蚀介质对氧化膜内的压应力和t-ZrO2的含量的影响有很大不同;Zr-4合金在LiOH或KOH水溶液中腐蚀时,Li 比K 进入氧化膜深而且浓度高;在LiOH水溶液中腐蚀时,氧化膜中OH-的浓度比在KOH水溶液中高.锆合金在LiOH水溶液中腐蚀时,氧化膜的生长主要是通过OH-从合金的表面向内扩散,与锆反应生成氧化锆和原子氢.Li 半径较小,容易进入氧化膜,因此较多的OH-进入氧化膜的深处,并与t-ZrO2中的氧空位反应,使t-ZrO2向m-ZrO2转变.这导致氧化膜出现裂纹,使氧化膜中的压应力松弛,降低氧化膜的保护能力,提高了锆合金的腐蚀速率. 相似文献
17.
《Materials Chemistry and Physics》2013,141(1):540-548
Carbide-derived carbons (CDCs) are obtained from vanadium carbide powders in the presence or absence of iron catalyst at chlorination temperatures of 400, 600, 800 and 1000 °C. The structural differences of the resulting carbons are characterized by low-temperature nitrogen sorption, Raman spectroscopy, X-ray diffraction, and transmission electron microscope techniques. Unlike monotonous increase in the degree of order for the CDC synthesized without addition of iron catalyst, a various decrease for the CDC synthesized with the catalyst is observed. This difference is due to the formation of many nano-diamonds during the CDC processing in the presence of iron catalyst. Variation in the specific surface area is associated with the degree of order in the CDC. CDC synthesized with iron catalyst at chlorination temperature of 800 °C shows the highest specific surface area, as well as the best electrochemical performance. 相似文献