S2O2-3对DP980高强钢在NaCl水溶液中的点蚀行为的影响

钢是一种冷轧双相高强度结构钢,成本低且具备良好的强度和塑性,在海工领域有巨大的潜在应用价值,但其在苛刻海水环境下的耐腐蚀性能,尤其是耐点蚀等局部腐蚀的能力有待深入研究.本文采用动电位极化法对DP980高强钢在含S₂O₃^2-离子的NaCl水溶液中的点蚀行为进行了研究,结果发现：在纯硫代硫酸钠水溶液中,DP980高强钢不发生点蚀;在不同质量分数的NaCl水溶液中,DP980高强钢发生点蚀,且随着Cl^-离子浓度的增大,DP980高强钢试样的耐点蚀性能下降明显;向NaCl溶液中加入浓度为0.001、0.01、0.1、1 mol/L的Na₂S₂O₃时,DP980高强钢试样的点蚀敏感性降低,点蚀受到明显抑制;随着Na₂S₂O₃浓度的升高,DP980高强钢的腐蚀主要以均匀腐蚀的形式发生;当试样浸泡在不同质量分数(0.1%、1%、10%)NaCl的1 mol/L Na₂S₂O₃溶液后,对试样表面腐蚀产物及腐蚀形貌进行扫描电镜观察及能谱分析,显示试样均发生均匀腐蚀,腐蚀产物为铁的硫化物,且未发现明显的点蚀.     

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.     

预氧化对一种镍基单晶高温合金的热腐蚀影响

为了解预氧化对镍基单晶高温合金的短时热腐蚀影响,采用涂盐法研究了一种高温合金经预氧化后在Na₂SO₄-NaCl盐膜条件下的热腐蚀行为,测量了不同预氧化处理时间合金的腐蚀动力学曲线,借助扫描电子显微镜(SEM)观察了合金腐蚀层截面的微观组织,并利用X-射线衍射仪(XRD)确定相结构.结果表明：未经过预氧化处理的合金表面腐蚀严重,热腐蚀增重质量最多达到0.033 mg/cm²,其腐蚀动力学曲线遵循抛物线规律,而经过预氧化处理后合金表面腐蚀明显改善;合金在900 ℃下的热腐蚀符合硫化氧化模型,腐蚀产物出现了分层结构;合金的主要腐蚀产物是NiO、Al₂O₃以及少量NiCr₂O₄、TiO₂、NiS₂等, 其中Al₂O₃、TiO₂等氧化物位于氧化层最外层;预氧化生成的Al₂O₃层对高温合金在Na₂SO₄-NaCl盐膜下的短时热腐蚀有明显的保护作用,腐蚀层厚度从170 μm降低至80 μm.致密的氧化物保护层能够显著阻止硫元素的扩散,提高合金的耐热腐蚀性能.     

Preparation of Gd2O2S:Pr Scintillation Ceramics by Pressureless Reaction Sintering Method

Fabrication of Gd₂O₂S:Pr scintillation ceramics by pressureless reaction sintering was investigated. The 2Gd₂O _3˙(Gd,Pr)2(SO ₄)_3˙mH₂O precursor was made by hydrothermal reaction using commercially available Gd₂O₃, Pr₆O₁₁ and H₂SO₄ as the starting materials. Then single phase Gd₂O₂SO₄:Pr powder was obtained by calcining the precursor at 750°C for 2 h. The Gd₂O₂SO₄:Pr powder compacts can be sintered to single phase Gd₂O₂S:Pr ceramics with a relative density of 99% and mean grain size of 30 μm at 1750°C for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd₂O₂S:Pr ceramics were examined. Luminescence spectra of the Gd₂O₂S:Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ³P₀-³H₄ transition of Pr³⁺ ions.     

回转体表面喷射电沉积Ni-P-ZrO2复合镀层耐腐蚀性能研究

为延长回转体零件的使用寿命,提高其耐腐蚀性能,本文利用喷射电沉积技术在45钢外圆表面制备Ni-P合金镀层和Ni-P-ZrO₂复合镀层,采用扫描电镜、腐蚀失重法和电化学测试分析等测试手段对Ni-P-ZrO₂复合镀层、Ni-P合金镀层和45钢基体在50 g/L NaCl溶液中的表面形貌和耐腐蚀性能进行研究,并探究腐蚀机理。研究表明:Ni-P-ZrO₂镀层相对Ni-P镀层表面致密度更高,缺陷较少;浸泡相同时间, Ni-P-ZrO₂镀层的失重量最小,腐蚀速率最小;电化学测试实验中,Ni-P-ZrO₂复合镀层的腐蚀电流最低(43.2×10^-5 A/cm²),共沉积ZrO₂颗粒后,Ni-P-ZrO₂复合镀层容抗弧半径更大,极化电阻值R_p增大为Ni-P合金的3倍,双层电容值C_d由4.743 8 μF/cm²降低为3.887 2 μF/cm²。在相同条件下腐蚀后,Ni-P-ZrO₂复合镀层的表面较为完好,腐蚀产物较少;Ni-P合金次之,有较多黑色腐蚀产物;45钢表面形貌最差。综上,采用喷射电沉积在回转体表面制备的Ni-P-ZrO₂复合镀层相对Ni-P合金镀层和45钢基体表现出更优良的耐腐蚀性能。     

新型层状化合物Ti2AlC在酸性溶液中的腐蚀行为

热压烧结得到高纯致密的Ti₂AlC块体.将Ti₂AlC在浓的和稀的HNO₃、HCl及H₂SO₄溶液中浸泡,得到试样的腐蚀速率及腐蚀类型.电化学方法测量试样在三种稀溶液中的腐蚀电位和腐蚀电流及动电位极化曲线.浸泡腐蚀实验发现,Ti₂AlC在酸中的腐蚀类型由点腐蚀发展到晶间腐蚀最后为剥蚀,腐蚀速率随着浸泡时间的延长而不断增大.其中在浓HNO₃中腐蚀速率最大,稀HCl的腐蚀速率最小.除H₂SO₄外,Ti₂AlC在浓酸溶液中的腐蚀率均大于其稀溶液.电化学实验表明,在稀HNO₃中自腐蚀电流最小,自腐蚀电位最大.稀H₂SO₄自腐蚀电流最大.在三种稀溶液中均出现钝化,其中稀H₂SO₄维钝区间最宽.     

锌电积用钛基掺聚苯胺热解碳氮SnO2-Sb2O3/PbO2电极

为了得到成本低、电催化活性高和稳定性强的锌电积用钛基二氧化铅电极,本文以聚苯胺热解碳氮(CN)作为钛基锡锑氧化物中间层的掺杂剂,继而沉积制备得到Ti/CN-SnO₂-Sb₂O₃/α-PbO₂-ZrO₂/β-PbO₂-TiO₂(Ti/CN-PbO₂)电极.用SEM、EDS对掺杂碳氮的锡锑氧化物层和Ti/CN-PbO₂电极进行表面形貌观测和元素分析,采用循环伏安,阳极极化曲线和交流阻抗分析掺杂CN的锡锑氧化物层对Ti/CN-PbO₂活性层电化学性能的影响,在30 ℃,150 g/L硫酸,50 g/L Zn²⁺电解液中进行电极强化寿命实验.结果表明,在锡锑氧化物的烧结过程中掺杂一定量的聚苯胺后,能够减轻氧化物层的龟裂现象,同时使得Ti/CN-PbO₂电极表现出更好的电催化活性,Ti/CN-PbO₂电极的加速寿命为925 h,为未掺杂CN的Ti/SnO₂-Sb₂O₃/α-PbO₂-ZrO₂/β-PbO₂-TiO₂(Ti/PbO₂)电极的2.5倍.     

CaMoO4:Eu3+纳米荧光粉的尺寸调控及光学性能研究

采用水热法制备了CaMoO₄:Eu³⁺纳米荧光粉.研究了反应温度、反应时间和Eu³⁺掺杂浓度对CaMoO₄:Eu³⁺纳米晶的颗粒尺寸以及光学性能的影响.利用XRD、SEM、FT-IR、UV-Vis和PL对所得样品的相结构、形貌、光学吸收以及发光性能进行了表征.研究结果表明：所合成样品均为四方晶系白钨矿结构的CaMoO₄纳米晶;一方面,随着水热反应温度的降低或者反应时间的缩短,CaMoO₄:Eu³⁺纳米晶都表现出尺寸减小的趋势,荧光强度逐渐减弱,样品的紫外可见光吸收带边发生蓝移;另一方面,随着Eu³⁺掺杂浓度的增加,CaMoO₄:Eu³⁺纳米晶的颗粒尺寸逐渐减小,样品的紫外可见光吸收带边出现红移.同时,在275 nm的光激发下,CaMoO₄:Eu³⁺荧光粉在614 nm处的⁵D₀→⁷F₂跃迁具有最高的荧光强度,观察到红光发射,且发现其荧光猝灭摩尔浓度为6%.     

HKUST-1/KCoFC复合材料的制备及其对Cs+的吸附研究

在这项工作中,制备了一种以金属有机配位聚合物(MOFs)材料(HKUST-1)为载体,通过KCoFC(Co(NO₃)₂与K₄Fe(CN)₆反应产物)功能化修饰后的新型复合材料,并通过FTIR、SEM、XRD对其进行表征。研究初始Cs⁺浓度、吸附时间、溶液pH值对吸附效果的影响,用吸附动力学和吸附等温线模型研究HKUST-1/KCoFC对Cs⁺的吸附过程。实验表明:在40 min内,Cs⁺吸附量迅速增加,复合材料对Cs⁺吸附量最佳的pH为8;HKUST-1/KCoFC对Cs⁺吸附过程符合准二级动力学和Langmuir模型。     

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.     

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.     

Effect of Y3+ codoping on luminescence decays of the 4I13/2 level in Er3+-doped Al2O3 powders prepared by a sol-gel method

The luminescence lifetime of the 0.01 mol.%-0.1 mol.% Er³⁺- and 0–20 mol.% Y³⁺-codoped Al₂O₃ powders prepared at a sintering temperature of 900°C in a non-aqueous sol-gel method has been investigated to explore the enhanced mechanism of photoluminescence properties of the Er³⁺-doped Al₂O₃ by Y³⁺ codoping. For the 0.1 mol.% Er³⁺-Y³⁺-codoped Al₂O₃ powders, the measured lifetime of Er³⁺ gradually increases with increasing Y³⁺ concentration. Consequently, codoping with 20 mol.% Y³⁺ leads to an increase in the measured lifetime from 3.5 to 5.8 ms. By comparing the measured lifetime for different Er³⁺ concentrations in the Al₂O₃ powders, the radiative lifetime of both the Er³⁺-doped and the Er³⁺-Y³⁺-codoped Al₂O₃ powders is estimated to be about 7.5 ms. Infrared absorption spectra indicate that Y³⁺ codoping does not change the-OH content in the Er³⁺-Y³⁺-codoped Al₂O₃ powders. The prolonged luminescence lifetime of the ⁴I_13/2 level of Er³⁺ in Er³⁺-doped Al₂O₃ powders by Y³⁺ codoping is ascribed to the decrease in the energy transfer rate between the Er³⁺ ions and the Er³⁺ and -OH, respectively, due to the suppressed interaction between Er³⁺ ions.     

Results of studying atmospheric corrosion in Vietnam 1995–2005

Vietnam is situated in the wet tropical zone; thus, atmospheric conditions are characterized by high temperatures and a long time of wetness (TOW). In addition, the salt air coming in from the sea causes a high chloride concentration in coastal areas. Furthermore, Vietnam is a developing country, which means that air pollution is increasing with the development of industry. These factors result in significant damage to materials by atmospheric corrosion. In this report, the results of a recent study on the corrosion of carbon steel and zinc-galvanized steel at 6–8 testing sites in Vietnam over 10 recent years (1995–2005) are focused on as well as the effects of environmental factors on atmospheric corrosion. The results showed that the corrosion of carbon steel is dominated by TOW, whereas zinc-galvanized-steel corrosion strongly depends on the chloride ion concentration in the air. The corrosion losses of both carbon- and zinc-galvanized steel fit the power model well with high correlation coefficients. In addition, the characteristics of the Vietnamese climate are introduced in the form of distribution maps of temperature (T), relative humidity (RH), total rainfall and TOW. A relationship between TOW, T and RH was found that enabled the calculation of TOW from T and RH data, which are available at meteorological stations. Finally, atmospheric corrosivity is determined on the basis of data on TOW, Cl^– and SO₂ concentrations, and the carbon steel corrosion rate. It is shown that in Vietnam, TOW is so long that the corrosion rate of carbon steel is in the C₃ category; nevertheless, Cl^– and SO₂ concentrations in the atmosphere are not high.     

GeO2 dopant induced enhancement of red emission in CaAl12O19:Mn phosphor

In order to search efficient red-emitting phosphors for white LEDs application, CaAl₁₂O₁₉:Mn⁴⁺ phosphors have been prepared by a combustion method assisted with GeO₂ flux. The influence of GeO₂ concentration and annealing temperature on the structure and luminescence intensity for the phosphors has been investigated. The mechanism for luminescence enhancement has been discussed. At GeO₂ doping concentration of 1.5 mol%, the red emission intensity increases by 81% under 330 nm UVA excitation. More isolated luminescence center Mn⁴⁺ ions rather than pairs of Mn⁴⁺-Mn²⁺ ions are formed in the lattice with the introduction of GeO₂ at high temperature oxidation, leading to the enhancement of the red emission. A feasible new way to enhance the red emission in CaAl₁₂O₁₉:Mn⁴⁺ phosphor is obtained.     

Results of studying atmospheric corrosion in Vietnam 1995–2005

Vietnam is situated in the wet tropical zone; thus, atmospheric conditions are characterized by high temperatures and a long time of wetness (TOW). In addition, the salt air coming in from the sea causes a high chloride concentration in coastal areas. Furthermore, Vietnam is a developing country, which means that air pollution is increasing with the development of industry. These factors result in significant damage to materials by atmospheric corrosion. In this report, the results of a recent study on the corrosion of carbon steel and zinc-galvanized steel at 6–8 testing sites in Vietnam over 10 recent years (1995–2005) are focused on as well as the effects of environmental factors on atmospheric corrosion. The results showed that the corrosion of carbon steel is dominated by TOW, whereas zinc-galvanized-steel corrosion strongly depends on the chloride ion concentration in the air. The corrosion losses of both carbon- and zinc-galvanized steel fit the power model well with high correlation coefficients. In addition, the characteristics of the Vietnamese climate are introduced in the form of distribution maps of temperature (T), relative humidity (RH), total rainfall and TOW. A relationship between TOW, T and RH was found that enabled the calculation of TOW from T and RH data, which are available at meteorological stations. Finally, atmospheric corrosivity is determined on the basis of data on TOW, Cl⁻ and SO₂ concentrations, and the carbon steel corrosion rate. It is shown that in Vietnam, TOW is so long that the corrosion rate of carbon steel is in the C₃ category; nevertheless, Cl⁻ and SO₂ concentrations in the atmosphere are not high.     

Tuning the luminescence color and enhancement of afterglow properties of Sr(4−x−y)CaxBayAl14O25:Eu,Dy phosphor by adjusting the composition

Color point tuning is an important challenge for improving the practical applications of various displays, especially there are very limited white color single hosts that emits in the white spectrum. In this paper, the possibility of color tuning by substituting part of host lattice cation (Sr²⁺ ions) by Ca²⁺ or Ba²⁺ ions in an efficient strontium aluminate phosphor, Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺, is reported and found to be very promising for displays. A detail study by replacing part of Sr²⁺ with Ca²⁺ or Ba²⁺ has been investigated. X-ray diffraction study showed that crystal structure of Sr₄Al₁₄O₂₅ is preserved up to 20 mol of Ca²⁺ ion exchange while it is limited to 10 mol of Ba²⁺ ions exchange. Substantial shift in the emission band and color were observed by substitution of Sr²⁺ by Ca²⁺ or Ba²⁺ ions. A bluish-white emission and afterglow was observed at higher Ca²⁺ ions substitution. Further, partial Ca²⁺ substitutions (up to 0.8 mol) resulted in enhanced afterglow of Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor. However, Ba²⁺ substitution decreased the fluorescence as well afterglow of the Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor significantly. The enhanced phosphorescence by partial Ca²⁺ substitution is explained on the basis of increased density of shallow traps associated with higher solubility of Dy³⁺ ions in to the host lattice due to equivalent size of Ca²⁺ and Dy³⁺ ions. Thus, Ca²⁺ substitution in the Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor is a promising method for tuning the emission color and improving the afterglow intensity of the phosphor.     

Effect of soil compositions on the electrochemical corrosion behavior of carbon steel in simulated soil solution

In this study, effect of cations, Ca²⁺, Mg²⁺, K⁺, and anions, SO₄^2–, HCO₃^–, NO₃^– on electrochemical corrosion behavior of carbon steel in simulated soil solution was investigated through potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results indicate that the Ca²⁺and Mg²⁺ can decrease the corrosion current density of carbon steel in simulated soil solution, and K⁺, SO₄^2–, HCO₃^–, and NO₃^– can increase the corrosion density. All the above ions in the simulated soil solution can decrease its resistivity, but they have different effect on the charge transfer resistivity. This finding can be useful in evaluating the corrosivity of certain soil through chemical analysis, and provide data for construction engineers.     

Effects of Zn doping on the structural and luminescent properties of Sr4Si3O8Cl4:Eu phosphors

Sr₄Si₃O₈Cl₄: Eu²⁺ phosphors were synthesized by the solid-reaction at high temperature. The emission intensity reaches a maximum at 0.08 mol% of Eu²⁺ concentration. The present paper mainly focused on the effects of Zn²⁺ on the crystallization behavior and photoluminescence (PL) properties of Sr₄Si₃O₈Cl₄:0.08Eu²⁺. Results suggested that no new phase is introduced by co-doping with a small amount of Zn²⁺ ions, but when co-doped with excessive amount of Zn²⁺ ions, Sr₂ZnSi₂O₇ appears. We find that the co-doping of a small amount of Zn²⁺ could remarkably improve the PL intensity of Sr₄Si₃O₈Cl₄:0.08Eu²⁺. When x = 0.05, the intensity of Sr₄Si₃O₈Cl₄:0.08Eu²⁺,xZn²⁺ was increased up to 2.3 times that of pure Sr₄Si₃O₈Cl₄:0.08Eu²⁺, which could be attributed to the flux effect of Zn²⁺ ions, and the Zn²⁺ doping reduces the opportunities of the energy transfer between Eu²⁺.     

The corrosion behaviours of polyaniline coated stainless steel in acidic solutions

Polyaniline (PANI) coating on stainless steel (SS) using oxalic acid as supporting electrolyte was obtained by using cyclic voltammetry technique. The corrosion performances of these PANI coated electrodes (SS/PANI) were determined in 0.05 M sulphuric acid and in 0.1 M hydrochloric acid solutions with electrochemical impedance spectroscopy and anodic polarization curves. The results clearly showed that SS/PANI immersed in sulphuric acid appeared to have better protective effect on the corrosion of SS than that of hydrochloric acid. The PANI coating was found to be stable and protective for extended immersion period in 0.05 M H₂SO₄.