红壤土浸出液中SO42-对铜包钢耐蚀性能的影响研究

本文采用扫描电镜/能谱分析(SEM-EDS)、动电位极化、电化学阻抗谱技术研究了铜包钢接地材料受SO₄^2-浓度影响的腐蚀行为.研究结果表明在含有不同浓度的SO₄^2-的红壤土浸出液浸泡20 d,铜包钢都已出现点蚀现象.随着SO₄^2-浓度从0.05~0.2 mol/L逐渐增加,铜包钢腐蚀程度呈现先增后减弱的趋势,在0.05 mol/L的SO₄^2-浸出液中浸泡20天腐蚀最为严重,已腐蚀至内层钢.由于0.05 mol/L的SO₄^2-浸出液中腐蚀后的铜包钢表面已被较多的不导电的腐蚀产物覆盖,因此实验结果显示其阻抗值最大和腐蚀速率最慢.     

纳米-Al2O3/SiO2加入量对MgO-Al2O3-SiO2复相陶瓷烧结机理的影响

为了探究纳米-Al₂O₃/SiO₂加入量对MgO-Al₂O₃-SiO₂复相陶瓷烧结行为的作用机理。以微米级MgO、纳米级Al₂O₃和SiO₂为主要原料制备陶瓷基复合材料。通过XRD和 SEM等检测手段对烧后试样的物相组成和微观结构进行测试与表征,重点研究Al₂O₃/SiO₂的加入对复相陶瓷物相组成、微观结构及烧结性能的影响。结果表明:随着Al₂O₃/SiO₂加入量的增大,试样烧后相对密度和烧后线变化率呈先增大后减小再增大的趋势,加入15%Al₂O₃/SiO₂(质量分数)的试样经1 500 ℃烧结后,其相对密度可以达到94%。引入的Al₂O₃/SiO₂与基体中的MgO生成镁铝尖晶石与镁橄榄石相,原位反应伴随的体积膨胀,抵消部分烧结过程中的体积收缩。Al₂O₃/SiO₂加入量为75%(质量分数)的试样经1 400 ℃烧结后,基体中有大量堇青石相生成,随着煅烧温度提高到1 500 ℃,堇青石分解所产生的高温液相促进了试样的烧结收缩。     

55%溴化锂溶液中Na2MoO4-B复合缓蚀剂对碳钢的缓蚀行为研究

本文采用失重法、电化学测试技术、EDAX能谱和X－射线衍射等方法考察了Na₂MoO₄-B复合缓蚀剂对55%LiBr+0.07 mol/L LiOH溶液中碳钢的缓蚀行为.结果表明,240 ℃时添加800 mg/L Na₂MoO₄-B复合缓蚀剂的55%LiBr+0.07 mol/L LiOH溶液中碳钢腐蚀速度为44.11 μm/a.沸腾的55%LiBr+0.07 mol/L LiOH溶液中添加复合缓蚀剂后碳钢电化学性能明显改善,腐蚀电位正移,钝化电位区间拓宽,钝化电流密度降低,常相位角元件CPE的Y₀值减小,反应电阻Rt值增加,缓蚀效率可达98.88%.Na₂MoO₄-B复合缓蚀剂中的B缓蚀剂可使55%LiBr溶液中Na₂MoO₄的溶解度提高至800 mg/L以上.Na₂MoO₄通过氧化作用可使碳钢表面形成一层主要由Fe₃O₄、MoO₂和MoO₃组成的致密钝化膜,从而起到较好的缓蚀作用.     

超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。     

SiO2玻璃原位反应合成Al/Al2O3复合材料

利用SiO₂玻璃具有易近成型、致密及各向同性的特点,通过SiO₂玻璃与铝熔体间的反应合成了Al/Al₂O₃复合材料,克服长期以来在合成Al/Al₂O₃复合材料时均采用颗粒反应物的局限。反应产物是一种组织均匀致密的Al 与Al₂O₃互为网络的Al/Al₂O₃陶瓷基复合材料。反应温度升高,整个反应产物中的Al的体积分数上升。Al/Al₂O₃复合组织在三维空间的真实形态中存在着Al相被Al₂O₃完全包围的形态,证明了网络状Al₂O₃组织形成的烧结机理。与合成Al/Al₂O₃的其它工艺相比,本工艺可在1000℃的较低温度进行,并具有反应速度快、断裂韧性和抗弯强度值高的特点。     

NiCo2O4/氧化石墨烯复合材料制备与电化学性能研究

为了研究NiCo₂O₄/氧化石墨烯(NiCo₂O₄/GO)复合材料的电化学性能,本文通过先水热合成前驱体再煅烧的方法制备了一系列NiCo₂O₄/GO复合材料.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学方法对其进行物理表征,其中以GO质量浓度为1 mg/mL悬浊液制备出的NiCo₂O₄ /GO-3复合材料呈类海胆状结构.在1 M KOH水溶液中使用循环伏安法、恒电流充/放电法和交流阻抗法研究了NiCo₂O₄/GO复合材料电化学性能.研究表明,与纯NiCo₂O₄相比,制备的NiCo₂O₄ /GO复合材料的比容量和赝电容性能均有明显提高,这主要是由于NiCo₂O₄ /GO复合材料中NiCo₂O₄与GO纳米片的相互作用形成的高孔隙率复合结构;NiCo₂O₄ /GO-3复合材料在电流密度为0.5~3.0 A/g时,比电容超过650 F/g,具有良好的倍率性能和高比容量.采用本文方法合成的NiCo₂O₄/GO复合材料,既提高了其倍率性能又保证了高比容量,是一种良好的超级电容器电极材料.     

纳米Al2O3颗粒增强新型铜基自润滑复合材料

以Cu-Ni-Y₂O₃-MoS₂-Graphite混合粉为基体,加入质量分数分别为0%、1%、2%、3%、4%的纳米Al₂O₃增强相,采用粉末冶金方法制备纳米Al₂O₃增强新型铜基自润滑复合材料。结果表明：随着铜合金粉末中纳米Al₂O₃颗粒含量的增加 , 所制备自润滑复合材料样品的密度下降,但硬度和压溃强度先上升后下降,在Al₂O₃含量为2%时硬度从HV 23.7增加到HV 35.1,压溃强度从189 MPa提高到276 MPa。由石墨和MoS₂组成的混合固体自润滑材料的摩擦系数小且稳定,约0.12。Al₂O₃质量分数为2%的样品磨损量最小,是未加Al₂O₃试样磨损量的1/7～1/8。铜基体经过镍、纳米Al₂O₃等弥散颗粒强化和固体润滑相石墨和MoS₂的加入,所制备的材料已具有一定的自润滑性能。     

团簇NiCo2S4的磁学性能

为探究团簇NiCo₂S₄的磁学性能,本文依据密度泛函理论(DFT)在B3LYP/Lan12dz水平下对团簇NiCo₂S₄进行优化计算,确定了三重态下的6种优化构型,并从轨道成单电子数、自旋布居数、磁矩、自旋密度差、轨道态密度图多个角度对构型进行分析。研究表明:团簇NiCo₂S₄的6种构型中,构型2^{(3)性能最优异,而热力学稳定性最好的构型1(3)在磁学性能方面表现一般,其余构型磁学性能相近。对于团簇NiCo₂S₄的磁性强度,在原子轨道上,s、p轨道对团簇NiCo₂S₄整体的磁性强度贡献较小,d轨道对整体的磁性强度贡献最大;Ni原子和自旋向上的α成单电子是团簇整体磁性强度的主要贡献者,其中,s轨道成单电子数的主要贡献者是S原子,p、d轨道主要是金属原子,Ni原子d轨道主要受α成单电子影响,Co、S原子既受α成单电子的影响又受β成单电子的影响。团簇NiCo₂S₄作为磁性材料时采用构型2(3)}作为模型基础,可以通过增大金属Ni比例来增强磁性。     

Y2O3添加量对Al2O3/ZrO2共晶陶瓷显微组织及力学性能的影响

为探索第三组元Y₂O₃添加对Al₂O₃/ZrO₂共晶陶瓷显微组织与机械性能的影响,本文利用低温度梯度的高温熔凝法制备了直径为20 mm的Al₂O₃/ZrO₂(Y₂O₃)共晶陶瓷块体,采用SEM、EDS及XRD技术对共晶陶瓷进行微结构分析,并利用维氏压痕法对其硬度和断裂韧性进行测试。SEM结果表明,凝固组织由群集的共晶团结构组成,随着Y₂O₃添加量的增加,共晶团形态由胞状转变为枝晶状,内部相间距在1~2 μm范围内变化。力学测试表明,Y₂O₃摩尔分数小于1.1%时,由于组织内部存在低硬度m-ZrO₂及微裂纹缺陷,故陶瓷硬度较低,约为(9.53±0.22 )GPa;当Y₂O₃摩尔分数为1.1%时,陶瓷硬度最大,约为(18.05±0.27)GPa;当Y₂O₃的摩尔分数大于1.1%时,由于共晶团边界区内气孔缺陷及粗大组织增多,引起陶瓷硬度值略有下降。低Y₂O₃摩尔分数添加时,陶瓷断裂韧性相对较高,约为(6.30±0.16)MPa·m^1/2,这与其内部存在大量微裂纹缺陷有关;随着Y₂O₃添加量的增加,陶瓷的微裂纹数量减少、边界区内缺陷增多,断裂韧性降低。     

原位Al2O3片晶/Ce-TZP和SrO·6Al2O3棒晶/Ce-TZP复合材料的制备与显微结构

通过在Ce-TZP基体中加入AlOOH及矿化剂TiO₂或反应剂SrCO₃制备了原位Al₂O₃片晶/Ce-TZP复合材料和原位SrO·6Al₂O₃棒晶/Ce-TZP复合材料。在烧结过程中TiO₂促进Al₂O₃晶粒发生显著的各向异性生长原位生成的片晶、Al₂O₃与SrCO₃发生反应,原位生成的高度各向异性的棒晶,它们在基体中分布均匀,具有较大的纵横比。烧结温度对片晶/棒晶的大小和含量有明显影响。通过在基体中原位形成片晶或棒晶,材料的力学性能有明显的改善。     

含H2S的NaCl溶液中溶解氧对PH13-8Mo钢腐蚀性能的影响

为研究新型马氏体沉淀硬化不锈钢PH13-8Mo在含饱和H_2S的NaCl溶液中的腐蚀行为,利用极化曲线、电化学阻抗谱等电化学测试和浸泡实验相结合的方法,通过扫描电子显微镜(SEM)和X射线光电子能谱分析技术(XPS),观察了该高强钢在含H_2S的除氧和不除氧的NaCl溶液中的腐蚀形貌,并对其腐蚀产物的成分进行了分析.结果表明:在除氧的NaCl溶液中,阳极极化曲线的形状发生了明显的变化,电化学阻抗谱的容抗弧的幅值也较未除氧的溶液中变小;在除氧的NaCl溶液中浸泡7 d后,由于H_2S水解后的S~(2-)或HS~-离子侵入到钝化膜的内部,并与钝化膜或金属基体发生反应,使得试样表面发生全面腐蚀,腐蚀产物主要为Fe、Cr、Ni、Mo的氧化物和硫化物;而在未除氧的NaCl溶液中浸泡后,试样表面仅发生局部腐蚀.     

The effect of YAG laser surface treatment on corrosion resistance of Al18B4O33w/2024Al composite

As a new material, aluminum borate whisker reinforced aluminum composite has been considered for a wide range applications. However, addition of reinforcements to aluminum will change the corrosion behavior significantly. A pulsed YAG laser installation was used to produce surface treatment on Al₁₈B₄O₃₃w/2024Al composite. Electrochemical method was used to study the corrosion resistance in 3.5% sodium chloride (NaCl) solution. The crystalline phases of the composites with and without laser surface treatment were analyzed using X-ray diffraction (XRD) measurement technique. The cross-section morphologies of the laser-treated composite were characterized by scanning electron microscope (SEM). Polarization experiments showed that the sensibility to pitting corrosion for the laser treated specimen was greatly lower than that of the untreated specimen. The reduction of reinforcement Al₁₈B₄O₃₃ whisker and intermetallics CuAl₂ on the surface of the laser-treated composite along with the formation of the homogeneous and defect free microstructure in the laser-modified layer led to improvement on the corrosion resistance of the laser-treated composite.     

Nb添加对Ti基非晶合金腐蚀及力学性能的影响

为研究微量添加Nb元素对Ti_(40)Zr_(10)Cu_(34-x)Pd_(14)Sn_2Nb_x(x为原子数分数,x=0、1%、3%、5%)非晶合金的耐腐蚀性能及力学性能的影响,本文利用动态极化曲线,分析了在0.144 mol/L的NaCl溶液及0.2 mol/L的PBS溶液中非晶合金Ti_(40)Zr_(10)Cu_(34-x)Pd_(14)Sn_2Nb_x(x=0、1%、3%、5%)的电化学性能,并通过材料拉伸试验研究了非晶合金块状样品的室温压缩性能.结果表明:在0.144 mol/L的NaCl溶液中,非晶合金样品在阳极区出现了自发钝化的特征,钝化电流密度在10~(-7)～10~(-8) A/cm~2,钝化电流密度随着Nb的添加略有降低,且点蚀电位随Nb原子数分数的增加分别为200、340、400和490 mV,说明微量添加Nb元素能有效提高Ti基非晶合金的耐点蚀能力,即在0.144 mol/L的NaCl溶液中Ti基非晶合金的耐腐蚀性随着Nb含量的增加而增强;在0.2 mol/L的PBS溶液中,因磷酸根离子的缓蚀作用,Nb添加导致的成分变化对非晶合金的腐蚀行为影响不大;此外,添加了原子数分数为1%及3%Nb的非晶合金,其压缩强度及塑性变形能力变化不大,但添加5%Nb的非晶合金因较大体积分数纳米晶的存在导致其室温断裂强度及塑性变形能力有明显下降.     

Laser surface hardening of AISI 420 stainless steel treated by pulsed Nd:YAG laser

The AISI 420 martensitic stainless steel was surface-hardened by a pulsed Nd:YAG laser. The influences of process parameters (laser pulse energy, duration time and travel speed) on the depth and hardness of laser treated area and its corrosion behavior were Investigated. In the optimum process parameters, maximum hardness (490 VHN) in the laser surface treated area was achieved. The pitting corrosion behavior was studied by potentiodynamic polarization technique in 3.5% NaCl solution at 25 °C. Metallographical and electrochemical corrosion studies illustrated beneficial effects of laser surface hardening by refining the microstructure and enhancing the pitting corrosion resistance of the martensitic stainless steel. The pitting corrosion resistance of laser surface treated samples in 3.5% NaCl solution depends on the overlap ratio clearly. The pitting potential (E_pp) decreased significantly by increasing the ratio of pulse overlapping.     

A study of the erosion-corrosion behavior of nano-Cr2O3 particles reinforced Ni-based composite alloying layer in aqueous slurry environment

To investigate the role of nano-Cr₂O₃ particles on the erosion-corrosion behavior of composite alloying layer, a nano-Cr₂O₃ particles reinforced Ni-based composite alloying layer was fabricated onto AISI 316L stainless steel (SS) via a duplex surface treatment, consisting of Ni/nano-Cr₂O₃ predeposited by electric brush plating, and subsequent Ni-Cr-Mo-Cu multi-element surface alloying by a double glow process. The microstructure and composition of composite alloying layer were characterized by means of X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The results indicated that the added nano-Cr₂O₃ particles were homogeneously distributed in the alloying layer and didn’t decompose or react with surrounding metal matrix under alloying temperature (1000 °C) condition. A series of electrochemical techniques, including potentiodynamic polarization, open circuit potential (OCP), current response and electrochemical impedance spectroscopy (EIS), was employed to evaluate the corrosion properties of nano-Cr₂O₃ particles reinforced composite alloying layer under various hydrodynamic conditions. Erosion-corrosion tests were conducted in 3.5% NaCl solution plus sand particles with varying concentration (50-150 g/L) at different rotation speeds (600-1100 rpm). To estimate the influence of the nature of different nano-particles on the erosion-corrosion property of composite alloying layer, nano-SiO₂ particles reinforced Ni-based composite alloying layer, single alloying layer and 316L SS was selected as the reference materials for all the corrosion and erosion-corrosion tests.     

含Ce2O3氧化物对改善双相不锈钢亚稳态点蚀的机理研究

利用扫描电镜、原子力显微镜、恒电位脉冲等研究了2205双相不锈钢在中性含Cl-环境下氧化物引起点蚀萌生的机理。实验发现MgO-Al_2O_3系夹杂物中MgO偏聚处以及MgO-Al_2O_3-CaO系夹杂物中CaO富集处会引起夹杂物处基体同周围基体接触电势差增加。此外,CaO富集处易使夹杂物表面出现显微缝隙并使基体裸露,产生亚稳态蚀坑。经Ce处理后发现夹杂物成分变为含Ce_2O_3·11Al_2O_3或Ce_2O_3·Al_2O_3为主的复合夹杂,夹杂物与基体接触电势差减小并且在含Ce_2O_3复合夹杂物处未发现点蚀萌生现象,最后阐述了非金属氧化物引起点蚀的机理以及Ce与氧化物反应的机制。     

The photooxidative destruction of C.I. Basic Yellow 2 using UV/S2O8 process in a rectangular continuous photoreactor

The photooxidative decolorization of C.I. Basic Yellow 2 (BY2), was investigated using UV radiation in the presence of peroxydisulfate (S₂O₈²⁻) in a rectangular photoreactor at experimental condition. S₂O₈²⁻ and UV-light showed negligible effect when they were used independently. Removal efficiency of BY2 was sensitive to the operational parameters such as initial concentrations of S₂O₈²⁻, BY2, light intensity, flow rate and pH. The conversion ratios of BY2 at the volumetric flow rates of 330, 500 and 650 ml/min were 84%, 79%, 51% in 30 min, respectively. Our results showed that light intensity was a beneficial parameter for dye removal. The results showed that in the presence of S₂O₈²⁻, the photooxidation quantum yield obtained was higher than direct photolysis quantum yield, suggesting that photodecay of BY2 was dominated by photooxidation. The electrical energy per order (E_EO) values for decolorization of BY2 solution was calculated. Results show that applying a desired peroxydisulfate concentration can reduce the E_EO.     

Sol-gel derived TiO2 coating on plasma nitrided 316L stainless steel

Titania film is coated on plasma nitrided 316L stainless steel by sol-gel method. Crystallization of titania as well as N loss and formation of Fe₂O₃ occurs during the annealing heat treatment. The titania film has short cracks within the grooves of plasma etched grain boundaries. With the increase of annealing temperature and duration, surface hardness of the samples is increased, but the toughness is decreased due to oxidization of the surface layer. The coating sample heat treated at 350 °C for 10 min and 450 °C for 10 min has better corrosion resistance than the nitrided stainless steel tested by the potentiodynamic polarization in 0.9% NaCl solution. Water contact angle of the titania film on the rough nitrided steel substrate decreases with UV irradiation treatment, reaching 17° after 3 h treatment.     

The influence of Na2CO3 content and Ni concentration on the physicochemical properties of nanometer Y-substituted nickel hydroxide

Nanometer Y-substituted nickel hydroxide was prepared by supersonic co-precipitation method with Na₂CO₃ as a buffer and NiCl₂ as a nickel source. The crystal structure, morphology, particle size distribution and electrochemical performance affected by the buffer (Na₂CO₃) content and Ni²⁺ concentration are characterized. The results indicate most of the samples are co-existence with α and β phases and the proportion of α-Ni(OH)₂ increases with the increase of Na₂CO₃, but decreases with the increase of Ni²⁺ concentration. The primary particles of samples are nanometer particles and the shape of primary particles transform from acicular to quasi-spherical with increasing Na₂CO₃ content, but converse process for the increase of Ni²⁺ concentration. The average particle size decreases initially and then increases. Complex electrodes were prepared by mixing 8 wt.% nickel hydroxides with commercial micro-size spherical nickel. The discharge capacities of samples increase initially and then decrease with increasing Na₂CO₃ content or decreasing Ni²⁺ concentration. When Na₂CO₃ content is 0.08 g and Ni²⁺ concentration is 0.2 mol/L, the sample has better electrochemical performance, such as larger discharge capacity (316.3 mAh/g at 0.2 C rate), lower charge voltage and higher discharge plateau, than those of other samples.