添加剂对Al-In-Ga-Pb合金阳极行为的影响

为改善铝阳极的性能,选用工业纯铝(99.8%),熔炼了Al-0.1 In-0.1 Ga-3Ph合金.在4 mol·L-1 KOH溶液中添加znO,KMnO4,Na2SnO3·4H2O,C4H4O6KNa4H2O,研究添加剂对合金阳极行为的影响.结果表明:溶液中添加znO后合金的析氢腐蚀得到明显的抑制,同时降低了合金的极化;KMnO4的加入可大幅提高合金的开路电位,但对抑制合金析氢腐蚀作用不明显;Na2SnO3·4H2O可提高合金的开路电位,降低极化.复合添加剂(11 mmol·L-1ZnO+0.61 mmol·L-1KMnO4)使合金开路电位负移,并有效抑制其析氢腐蚀,提高了阳极活性,综合性能较佳.     

添加稀土离子提高嗜热梭菌发酵微晶纤维素生产乙醇的产率

研究添加十二种稀土离子(La~(3+)、Ce~(3+)、Nd~(3+)、Gd~(3+)、Sm~(3+)、Eu~(3+)、Dy~(3+)、Er~(3+)、Yb~(3+)、Y~(3+)、Ho~(3+)和Lu~(3+))对嗜热梭菌(Clostridium thermocellum)发酵微晶纤维素生产乙醇产率的影响。分别在培养初始(0h)和生长对数期(12h)添加10~(-4)mol/L、10-5mol/L和10-6mol/L的十二种稀土离子,观察其对C.thermocellum发酵微晶纤维素生产乙醇产率的影响。研究发现,在培养初始分别添加10~(-4)mol/L的Ce~(3+)、10~(-6)mol/L的Nd~(3+)、10~(-6)mol/L的Gd~(3+)或10~(-4)mol/L的Er~(3+)时,乙醇产率提高显著。其中,在培养基中添加10~(-6)mol/L的Nd~(3+)时,乙醇产率最高,为26.62%,比空白对照组的产率提高了98.36%。还发现,这种乙醇产率增加的现象在稀土离子洗脱后还能维持恒定,菌种性能也能稳定遗传,推测这些稀土离子对C.thermocellum起到了诱变作用。     

用离子膜电解槽无硒电沉积金属锰

研究了用阴离子膜电解槽在硫酸盐体系中无硒电解金属锰,采用循环伏安法研究了阴极电化学机制。单因素条件试验确定的最佳电解条件为:锰离子质量浓度30g/L,硫酸铵质量浓度135g/L,电解温度35℃,阴极液pH=7.7,电流密度450A/m2,SO2添加量为0.4g/L。最佳条件下,电解效率达到82%,直流电耗为4 985kWh·t-1,电解产品为α-Mn,质量符合国家标准。阴离子交换膜可以减弱阴极浓差极化,有效区分锰沉积峰和析氢还原峰;SO2添加剂可显著抑制析氢反应,降低锰沉积电流,减小直流电耗。     

表面纳米化处理对IF钢电化学析氢行为的影响

利用阴极极化曲线、交流阻抗谱,对超音速微粒轰击（USPP）表面纳米化处理（SNC）的IF钢在30%NaOH溶液中的析氢行为进行了研究,同时利用XRD和SEM分析了表面纳米化前后IF钢的晶粒度和表面形貌。试验证明,经SNC处理后,IF钢析氢过电位比基材降低200 mV;SNC＋1%平整的IF钢比基材析氢过电位低300 mV以上;经处理后IF钢真实表面积比原IF钢板分别增大18倍和21倍,其表观析氢活化自由能分别由51.7 kJ/mol降低为26.5 kJ/mol和21.7 kJ/mol,仅为原IF钢板的50%。     

中碳轴承钢C56E2氢析出行为研究

氢是降低钢的力学性能重要因素之一,热轧态中碳轴承钢C56E2钢中氢含量低于0.02×10^-6,相较于液态钢中氢含量析出率达到95%～98%。热轧态钢中存在碳化物Fe₃C和析出物/夹杂物两类主要氢陷阱,残余氢主要为析出物/夹杂物陷阱氢。在25℃、2 mA/cm²恒电流法、0.1 mol/L NaOH溶液中进行0～216 h化学充氢后两种陷阱所吸附氢含量均有增加,析氢量随着充氢时间的延长先升高后下降;碳化物Fe₃C陷阱析氢量(0～0.0107)×10^-6占TDS总析氢量比率随着充氢时间延长而升高,而析出物/夹杂物陷阱析氢(0.0035～0.0190)×10^-6量占比相应下降。氢在氢陷阱的吸附和空穴初始占有率为影响TDS析氢自由能差异的主要因素,陷阱氢的析氢活化能随着充氢时间的延长而增加。碳化物Fe₃C陷阱氢析出活化能随着该类型氢含量增加而降低,析出物/夹杂物陷阱氢析出活化能随析氢峰值点累积析氢量增加而升高。     

酸处理对PtCu/CeO_x复合膜电极析氢性能的影响

通过IBS技术制备PtCu/CeOx复合膜电极,在不同的酸处理条件下对膜电极进行后处理。XRD分析结果表明,PtCu/CeOx复合膜电极表层形成了PtCu置换固溶体合金,原有的Pt晶格受压应力收缩,导致晶面间距缩小。AFM分析结果表明,经过50℃酸处理后的PtCu/CeOx复合膜电极表面平均粗糙度增大4.2%。电化学性能测试结果表明,在不同的酸处理条件下,电极的析氢催化性能有显著提高,用50℃的0.5 mol/L H2SO4溶液酸处理30 min可以使其析氢电位正移30.8%,同时析氢性能提升约21.6%。     

无定形MoOx/C复合材料的制备与电催化析氢性能

钼基氧化物是典型的过渡金属氧化物,具有特殊的能带结构,是一种极具潜力的非贵金属电解水析氢催化材料。本研究利用溶液燃烧合成技术,以四水钼酸铵为钼源,葡萄糖为碳源,合成了无定形结构的MoO_x/C复合材料,研究了葡萄糖添加量对产物相态和显微结构的影响,评价了MoO_x/C的电催化析氢性能。研究表明,随葡萄糖添加量的增加,MoO_x的相态与形貌从粗大颗粒→细小颗粒和部分无定形态→完全无定形结构进行演变。当葡萄糖与钼源的摩尔比值为2.5时,可合成无定形结构的MoO_x/C复合材料,将其作为析氢催化剂,在0.5 mol/L H2SO4条件下的起始电位为132 mV,过电位(η10)为212 mV,塔菲尔斜率为84.9 mV/dec,具有良好的析氢催化性能和优异的循环使用稳定性,这归因于无定形结构提供了丰富的催化活性位点以及碳的引入提高了导电性和结构稳定性。     

Al_(88)Ce_8Co_4非晶合金在NaCl溶液中的腐蚀行为研究

利用极化曲线测试方法、交流阻抗技术研究了Al88Ce8Co4非晶合金在NaCl溶液中的电化学腐蚀行为。研究结果表明,Al88Ce8Co4非晶合金在NaCl溶液中具有很好的耐腐蚀性能。NaCl溶液浓度严重影响Al88Ce8Co4非晶合金的抗腐蚀性能,在所研究的浓度范围内,极化曲线都表现出明显的钝化趋势,EIS图谱均由单一的容抗弧构成。在浓度为0.5mol/L~2mol/L范围内,随浓度的增加,自腐蚀电位有向负方向移动的趋势,腐蚀电流密度逐渐降低,电荷转移电阻逐渐增大,当浓度达到4mol/L时,自腐蚀电位向负方向移动较大,相较于2mol/L时,腐蚀电流密度又有所升高,电荷转移电阻有所降低。     

钕铁硼二次废料溶析结晶法制备硫酸亚铁

针对钕铁硼二次废料回收铁元素时存在操作复杂、能耗高等问题,以硫酸亚铁溶液模拟废料酸浸还原液,采用溶析结晶法回收溶液中的硫酸亚铁。通过实验分别测定硫酸亚铁在纯水和乙醇-水溶液两种体系中的溶解度,并以Apelblat方程对数据进行拟合,确定了实验的可行性。选用乙醇为溶析剂,考察了乙醇用量、硫酸亚铁初始浓度、温度、搅拌速度、乙醇加入方式及陈化时间等对结晶率的影响。在乙醇与硫酸亚铁溶液体积比为1∶1、硫酸亚铁初始浓度200 g/L、温度283.15 K、添加约溶质质量1%的晶种、连续加入乙醇的速度为10 mL/min、搅拌速度150 r/min和陈化时间60 min时,结晶率达95.28%。采用该法回收真实二次废料还原液中的硫酸亚铁,并利用ICP-AES、XRD、TGA和SEM对产物进行表征,结果表明,采用溶析结晶法制备的硫酸亚铁产品纯度高,杂质含量低。     

新型铝青铜合金粉体材料涂层耐腐蚀性能研究

采用扫描电镜、能谱及静态浸泡腐蚀实验等方法研究了雾化法制备的新型铝铜合金粉末(Cu-14Al-X)通过等离子喷焊的方式作为涂层材料分别在3.5mol/L NaCl溶液、10mol/L HCl溶液、5mol/L H2SO4溶液中的腐蚀行为以及耐腐蚀性。结果表明,这种新型的涂层材料具有良好的耐腐蚀性能。涂层中的(α+γ2)共析体与β′相、α相和K相相比,具有优先腐蚀倾向,涂层发生的主要是脱铝腐蚀。在3种溶液环境下的腐蚀速率由小到大依次为:5mol/L H2SO4溶液,10mol/L HCl溶液,3.5mol/L NaCl溶液。     

石墨炉原子吸收光谱法测定锡锭中痕量铝

建立了石墨炉原子吸收光谱法测定锡锭中痕量铝的方法,确定了样品分解方式和石墨炉原子吸收光谱测定铝的最佳条件。以盐酸-过氧化氢（V（盐酸）∶V（过氧化氢）= 2.5∶1.5）分解样品,在16 g/L柠檬酸、0.12 mol/L盐酸介质中,以4 g/L硝酸钙为基体改进剂进行铝的测定。结果表明：在选定的酸度介质中,不需要挥锡,锡不会水解,样品溶液保持清亮时间长;硝酸钙提高了测铝的灵敏度,并增强了抗氯化物干扰的能力;样品中锡及共存元素不干扰测定。该方法的检出限为2.96 μg/L,线性范围为0～100 μg／L,相关系数r≥0.998 0。方法用于锡锭中铝的测定,相对标准偏差为6.6%,回收率在100%～119%之间,样品测定值与标准加入法及ICP-AES法测定值相符。     

甲基百里香酚蓝分光光度法测定铝合金中钛

准确、灵敏、快速地测定钛在铝合金材料中的含量,对提高铝合金材料的机械性能有重要意义。通过加入氢氧化钠溶液和双氧水溶解样品, Fe³⁺干扰可通过加入酒石酸钾钠溶液来消除, Zn²⁺干扰可通过加入二巯基丙磺酸钠溶液来掩蔽,Cu²⁺的干扰可通过加入铜试剂的方法来去除。使用稀H₂SO₄来控制体系的酸度,加入混合增敏剂阿拉伯树胶和聚乙烯醇,常温下甲基百里香酚蓝溶液会与钛发生显色反应形成稳定的蓝紫色络合物,利用该特性,实现了分光光度法对铝合金中钛的测定。实验结果表明:显色体系最大吸收峰为570 nm,钛质量浓度在小于1.6 μg/mL时与吸光度呈线性关系,线性相关系数r为0.999 4,方法检出限为2×10^-8(质量分数),表观摩尔吸光系数为4.7×10⁴ L·mol^-1·cm^-1。方法用于测定铝合金样品中钛的含量,结果的相对标准偏差(RSD,n=6)为2.1%~3.0%,加标回收率在97%～105%之间,测定值与采用GB/T 20975.12—2008的测定值基本一致。     

新型铝合金阳极在NaOH碱性溶液中的腐蚀行为

制备了两种不同含量的Al-Ga-In-Zb-Mg-Mn合金和Al-Ga-In-Sn-Zn-Mg-Mn合金，共三种新型铝合金阳极材料。研究了该系列合金在4mol／LNaOH碱性溶液中的自腐蚀速率和电化学性能。结果表明：在不同的电解液中铝阳极表现出不同的自腐蚀速率和不同的电极电位；合金元素的均匀分布可极大地降低铝阳极的自腐蚀速率。研制出的新型铝合金阳极材料具有优良的电化学性能和良好的耐腐蚀性能，No．1、No．1-1和N0．3阳极在80℃、电流密度为800mA／cm^2条件下、在添加偏铝酸盐时的电解液中，其稳态平均电位分别达到了-1．576V、-1．574V和-1．53V（vs．Hg／HgO）；同时铝合金阳极具有良好的铸造性能和机加工性能。     

Study on Pre-oxidation of a High-Arsenic and High-Sulfur Refractory Gold Concentrate with Potassium Permanganate and Hydrogen Peroxide

For arsenic-containing refractory gold concentrate, gold recovery by leaching is extremely difficult due to the encapsulation of gold in arsenopyrite and pyrite. In this work, the pre-oxidation of a high-arsenic and high-sulfur refractory gold concentrate in the acidic potassium permanganate or hydrogen peroxide solutions has been investigated. The studied parameters include pre-oxidation time, acidity, pre-oxidation temperature, ethylene glycol addition and oxidant concentration. When potassium permanganate of 0.25 mol/L is used as oxidant, 61.4% of arsenic and 51.8% of iron can be removed, respectively. The results of kinetics analysis indicate that the oxidative dissolution of arsenopyrite during the pre-oxidation process is controlled by the product layer diffusion, with an activation energy of 7.92 kJ/mol. The stability of hydrogen peroxide can be significantly improved by increasing both sulfuric acid concentration and ethylene glycol addition when hydrogen peroxide is used as oxidant. Under optimum conditions, arsenic removal ratio of 57.2% and iron removal ratio of 51.9% have been achieved with hydrogen peroxide of 2.5 mol/L, sulfuric acid of 0.75 mol/L and ethylene glycol of 30 mL/L. The gold extraction of refractory concentrate is only 11.5% in the copper–ammonia–thiosulfate leaching solutions without pre-oxidation. A gold extraction of 71.8% and significant decrease in thiosulfate consumption from 28.2 to 5.7% have been observed for the concentrate after pre-oxidation.     

稀土对X70管线钢腐蚀行为的影响

试验用X70管线钢(/%:0.12C、0.20Si、1.60Mn、0.005P、0.005S、0.10V、0.10Nb、0～0.15RE)用10kg真空感应炉冶炼。采用电化学和失重分析法研究了微量稀土对X70管线钢在0.1 mol/L Na₂SO₄水溶液中的腐蚀行为。试验结果表明,微量稀土可降低管线钢腐蚀电流i_corr,改善腐蚀形貌。随着稀土加入量的增加,腐蚀电流减小,当钢中的RE含量由0增加至0.10%时腐蚀速率由7.43μg/(cm².day)降至0.29μg/(cm².day)。稀土的最适宜加入量是0.10%。     

Mechanisms of bradykinin-induced cerebral vasodilatation in rats. Evidence that reactive oxygen species activate K+ channels

BACKGROUND AND PURPOSE: Relatively little is know regarding mechanisms by which reactive oxygen species produce dilatation of cerebral arterioles. The goal of this study was to test the hypothesis that vasodilator responses of cerebral arterioles to bradykinin, which produces endogenous generation of reactive oxygen species, involve activation of calcium-dependent potassium channels. METHODS: We used a cranial window in anesthetized rats to examine effects of catalase (which degrades hydrogen peroxide) on responses to bradykinin. In addition, we examined effects of tetraethylammonium (TEA) and iberiotoxin, inhibitors of calcium-dependent potassium channels, on responses of cerebral arterioles to hydrogen peroxide, bradykinin, and papaverine. RESULTS: In cerebral arterioles (baseline diameter = 40 +/- 1 microns) (mean +/- SE), hydrogen peroxide (10 and 100 mumol/L) produced concentration-dependent dilatation. TEA (1 mmol/L), an inhibitor of calcium-dependent potassium channels, produced marked inhibition of vasodilatation in response to hydrogen peroxide. For example, 100 mumol/L hydrogen peroxide dilated arterioles by 13 +/- 2% in the absence and 4 +/- 1% (P < .05 versus control) in the presence of TEA. Bradykinin (10 nmol/L to 1 mumol/L) also produced concentration-dependent dilatation of cerebral arterioles that was inhibited completely by catalase (100 U/mL). TEA or iberiotoxin markedly inhibited vasodilatation in response to bradykinin. For example, 100 nmol/L bradykinin dilated arterioles by 21 +/- 3% in the absence and 2 +/- 2% (P < .05 vs control) in the presence of iberiotoxin (50 nmol/L). CONCLUSIONS: These findings suggest that dilatation of cerebral arterioles in the rat in response to hydrogen peroxide, or hydrogen peroxide produced endogenously in response to bradykinin, is mediated by activation of calcium-dependent potassium channels. Thus, activation of potassium channels may be a major mechanism of dilatation in response to reactive oxygen species in the cerebral microcirculation.     

Molecular dynamics simulation of aluminum inhibited leaching during ion-adsorbed type rare earth ore leaching process

Molecular dynamics simulation was adopted to study the interaction between sulfosalicylic acid and aluminum,lanthanum and yttrium,and adsorption on kaolinite surfaces.A complexation reaction occurs between sulfosalicylic acid and aluminum,with an interaction energy of-10472.05 kJ/mol.O—Al covalent bonds are formed with a peak value of 7.93,while there is only weak adsorption between sulfosalicylic acid and rare earth ions.A hydrogen bonding reaction with 13605.82 kJ/mol energy occurs between sulfosalicylic acid and the surface of kaolinite(100).Thus,sulfosalicylic acid can form a complex with free aluminum ions,and can also be adsorbed on kaolinite by hydrogen bonding with aluminum in kaolinite(100) surfaces.Leaching of ion-adsorbed type rare earth ore was performed with aluminum inhibited,results show that when sulfosalicylic acid dosage increases from 0 to 0.15 wt%,aluminum ion concentration in the leaching solution decreases from 273.23 to 47.19 mg/L.And the effect of leaching pH value on the effect of sulfosalicylic acid on aluminum inhibition was studied,the result shows that,when the leaching pH value is 4.0—5.0,the rare earth leaching rate and the aluminum ion concentration basically remain unchanged.The molecular dynamics simulation results were verified by detection and analysis of XPS and SEM.     

百里香酚蓝分光光度法测定铝合金中钛

采用氢氧化钠溶液和双氧水溶解样品,加入酒石酸钾钠溶液消除Fe³⁺的干扰,加入硫脲溶液提高Cu²⁺的允许量,在稀硫酸介质中,增敏剂阿拉伯树胶存在下,钛与显色剂百里香酚蓝发生反应形成稳定的蓝紫色络合物,建立了百里香酚蓝分光光度法测定铝合金中钛的方法。结果表明:络合物最大吸收峰位于590nm,溶液中钛质量浓度在0.1~2μg/mL范围内符合比尔定律,方法检出限为 0.03μg/mL,表观摩尔吸光系数为3.7×10⁴ L·mol^-1·cm^-1。方法用于铝合金标准样品中钛含量的测定,测定值与认定值基本一致,钛测定结果的相对标准偏差(RSD,n=6)为2.3%和3.4%。     

Hydrogen-facilitated corrosion and stress corrosion cracking of austenitic stainless steel of type 310

The effects of hydrogen précharge and stress on anodic dissolution for Type 310 austenitic stainless steel (ASS) have been investigated. An experiment determining the effect of hydrogen on stress corrosion cracking (SCC) was carried out in a boiling 42 pct MgCl₂ solution and in a 2.5 mo/L H₂SO₄ + 1 mol/L HC1 solution. The results showed that both hydrogen and stress would increase the dissolution rate, and the effects of hydrogen and stress on the dissolution rate were synergistic rather than simply additive. Hydrogen lowered the threshold stress and the shortened fracture time of SCC in a boiling MgCl₂ solution by a factor of 1/5 and 10, respectively.     

碘量法测定铁矿石中全铁及磁性铁的分析方法探讨

采用碘量法对不同类型铁矿石尤其是常规酸、碱分解方法难以分解完全的矿石中铁的测定进行分析研究,使用过氧化钠碱熔法测定全铁,并对传统磁性铁测定方法进行了改进。分析了不同酸度、碘化钾加入量、放置时间对测定结果的影响,以及干扰元素的影响及去除。实验方法全铁分析时过氧化钠加入量确定为3.0g,磁性铁分析时过氧化氢加入量确定为1滴(300g/L);全铁和磁性铁分析反应起始酸度控制在0.5~1.0mol/L,临近终点酸度控制在pH值为3.0~4.0;碘化钾溶液加入量为10mL(250g/L);并成功地分离了干扰元素。选取不同类型和含量的铁矿石标准物质和实际样品分别采用实验方法和传统的重铬酸钾无汞滴定法对全铁和磁性铁做方法对比试验,实验方法的测定结果与认定值或铬酸钾无汞滴定法的测定值基本一致。实验方法全铁测定结果的相对标准偏差(RSD)在0.076%~0.19%之间,磁性铁测定结果RSD在0.083%~0.13%之间,正确度与精密度均符合DZ/T 0130—2006质量管理规范的要求。