微波固相烧结制备La0．7Sr0．3-xCaxCo0．9Fe0．1O3-δ阴极材料及性能表征

以碳酸盐和氧化物为原料，采用微波固相烧结法制备了La0．7Sr0．3-xCaxCo0．9Fe0．1O3-δ（简称：LSCCF，x=0．05，0．10，0．15和0．20）粉料。用XRD和sEM对LSCCF粉料的晶体结构和颗粒形貌进行了研究。结果表明：微波固相反应在1200℃下烧结0．5h便可以形成密度为5．366g／cm^3，晶粒尺寸小于500nm钙钛矿结构的粉料。而常规固相反应法在1300℃下烧结7h只形成了密度为3．426g／cm^3，晶粒尺寸小于2000nm钙钛矿结构的粉料。电导率测量结果表明：随着烧结温度的升高和Sr^2＋含量的增加，LSCCF样品的电导率变大，600℃～800℃范围内微波烧结制备的La0．7Sr0．3-xCaxCo0．9Fe0．1O3-δ样品的电导率最小值为672S／cm。且高于常规固相烧结制备的相同组成样品的电导率最小值425S／cm。LSCCF粉料与Ce0.8Sm0.2O2电解质的混合物在800℃下烧结10h后没有新相生成，表明LSCCF粉料与Ce0.8Sm0.2O2电解质具有良好的化学相容性。     

原位热压制备Ti3Si0．8Al0．4C1．95固溶体陶瓷

以Ti、Si、Al和C（石墨）元素粉为原料，采用原位热压烧结法制备了高纯度的Ti3Si0．8Al0．4C1．95层间固溶体陶瓷块体材料，研究了合成温度对产物纯度的影响，测试分析了制备材料的相组成及显微结构，测试了制备材料的密度、抗弯强度及电阻率等特性。结果表明，适当的热压烧结温度为1550℃左右，偏高或偏低都导致TiC及Ti5Si3等杂相的生成；微观结构为典型的板状晶，晶粒内部的层状结构清晰可见；材料的密度、抗弯强度和电阻率均介于Ti3SiC2和Ti3AlC2两者之间。     

Ca0．6Mg0．4Zr4（PO4）6纳米粉体的共沉淀法合成与表征

采用直接共沉淀法，以等化学计量比的Ca（NO3）2·4H2O、Mg（NO3）2·6H2O、ZrO（NO3）2·8H2O和NH4H2PO4等无机盐为原料，控制共沉淀反应过程pH=9时，合成了单相的Ca0．6Mg0．4Zr4（PO4）6（C0．6M0．4ZP）纳米粉体，并采用TG-DSC、XRD、纳米粒度分析、SEM和TEM等分析测试手段对合成的Ca0．6Mg0.4Zr4（PO4）6（C0．6M0．4ZP）纳米粉体进行了测试表征。TG-DSC和XRD分析表明，沉淀物经900℃左右热处理即可获得单相的C0．6M0．4ZP纳米粉体。SEM和TEM分析表明，沉淀物在900℃煅烧3h，可获得颗粒粒径为30nm左右的C0．6M0．4ZP纳米粉体，粉体颗粒呈球形，但合成纳米粉体存在团聚现象，导致采用纳米粒度分析仪测定的纳米粉体颗粒尺寸主要分布在30～70nm之间，平均粒径达到45nm。合成C0．6M0．4ZP纳米粉体制备的干压试样，在1300℃保温3h烧成后相对密度达到95．3％，抗弯强度为125．7MPa。     

凝胶注模制备La0．8Sr0．2MnO3多孔阴极材料

采用凝胶注模技术原位合成造孔剂制备出开孔气孔率为20％～30％的La0．8Sr0．2MnO3多孔阴极材料。结果表明，合适的烧结温度为l100℃～1150℃；开口气孔位于三角晶界，中位孔径约为400nm；多孔材料的电导率随着温度的升高而升高，由ln(σT)-1／T曲线，可得电导活化能Ea为10．99kJ／mol。     

尖晶石型LiCo0．05Ni0．05Mn1．9O3．9F0．1的合成与表征

以阴阳离子复合掺杂为基础，采用超声共沉淀法、Pechini法和高温固相法合成尖晶石型掺杂锰酸锂前驱体，使用3段热处理方式，即650℃预烧、780℃烧结、550℃回火制备得到掺杂尖晶石LiCo0．05Ni0．05Mn1.9O3．9F0.1。通过化学容量分析测定Mn含量和平均价态，用粒度分布、电镜扫描（SEM）、X射线衍射（XRD）、电化学性能测试对产物进行表征。结果表明产物的Mn含量和平均价态与理论值吻合。3种合成方法相比，超声共沉淀法产物的粒径最窄，比表面积最小（14919cm^2／cm^3），晶型完整，衍射强度最大，结晶性能最佳，晶格常数为0．821nm，晶粒尺寸为57．48nm：经装配电池电化学性能测定，超声共沉淀法产物的比容量更高，循环性能更稳定，经30次循环后容量衰减仅7．2％。     

Ba（Sn0．1Ti0．9）O3粉体的熔盐法制备与性质

采用熔盐法研究了Ba（Sn0．1Ti0．9）O3铁电体粉体的制备工艺和粉体性质。探讨了在熔盐催化下，合成温度对Ba（Sn0．1Ti0．9）O3反应完全程度及粉体形态的影响。结果表明，当反应温度达到900℃时，在熔盐环境下即可合成单相固体Ba（Sn0．1Ti0．9）O3，随着反应温度提高，粉体尺寸变化不大，但当温度超过950℃时出现晶粒异常长大趋势。烧结陶瓷的形貌和介电性质显示陶瓷粉体烧结活性好且介电性质优良。     

Ag^＋掺杂Na0．5K0．5NbO3无铅压电陶瓷的无压烧结及性能研究

铅基压电陶瓷在制备、使用及废弃处理过程中都会造成环境污染，随着环保意识的增强，无铅压电陶瓷必将逐步替代铅基压电陶瓷。Na0．5K0．5NbO3是一种很有潜力的无铅压电陶瓷，掺杂各种元素提升Na0．5K0．5NbO3陶瓷的压电性能成为当今研究热点之一。本研究以Ag2O、Na2CO3、K2CO3、Nb2O5为原料，经750℃焙烧分别合成了Na0．5K0.5NbO3和AgNbO3粉料，再经配料、混料与成型，在1060℃埋粉烧结，制备出Ag^＋掺杂的Na0.5K0．5NbO3无铅压电陶瓷（xAgNbO3-（1-x）Na0.5K0．5NbO3，ANKN），并在较宽成分范围内（Ag^＋含量，x=0-50at％）系统研究了Ag^＋掺杂对ANKN陶瓷性能的影响。XRD结果表明，ANKN陶瓷的主相为钙钛矿型结构，当x〉16at％，开始出现K5-75Nb10．85O30杂相，随着Ag掺杂量的增加，杂相的衍射峰增强。电学性能测试结果表明，当x〈20at％，随Ag掺杂量的增加ANKN陶瓷的压电常数、介电常数等略有升高；当x〉20at％，ANKN陶瓷的各项性能均开始降低；Ag掺加量为x=16at％时ANKN陶瓷性能最佳，压电常数d33达到110pC／N，平面机电耦合系数kp为30％，相对介电常数εr为358，居里温度Tc为300℃。     

高温稀土永磁Sm（Co0．72Fe0．15Cu0．1Zr0．03）7．5的烧结和磁性能研究

采用粉末冶金法制备高温稀土永磁Sm（Co0.72Fe0．15Cu0.1Zr0．03）7.5，研究了烧结温度对磁体磁性能的影响。结果表明：烧结温度过低，则磁体的致密度较低，难以获得优良的磁性能；烧结温度过高，则Sm挥发，磁体的Sm含量降低，磁性能恶化。磁体的最佳烧结条件为：温度1215℃，保温45min。在上述条件制备的磁体在25℃及500℃时的剩磁夙、内禀矫顽力Hci、最大磁能积（BH）max分别为：0．94T，2276．6kA／m，171．9kJ／m^3及0．67T，509．4kA／m，81.2kJ／m^3；磁体的占．日退磁曲线在500℃时保持为直线，内禀矫顽力温度系数声（25℃-500℃）为-0，16％／℃，最高使用温度达到533℃。     

复合掺杂对YSZ电解质材料烧结性与电性能的影响

采用高温固溶法制备Sc2O3（Dy2O3）和Yb2O3复合掺杂YSZ电解质材料，研究了复合掺杂对YSZ烧结性和电性能的影响。结果表明：随着Sc2O3含量的增加，试样烧结密度降低（1600℃烧结密度由5．82g／cm^3降至5．24g／cm^3），而Dy2O3却能提高烧结密度（1600℃烧结密度由5．63g／cm^3增至5．86g／cm^3）：当掺杂总量x，％）为8～8．6时，材料电导率得到大幅度提高（1000℃时，0．18S／cm）；1nσ-1000／T呈现较好的线性关系，说明电导率σ与温度T之间关系符合Arrhenius公式；XRD分析表明复合掺杂YSZ电解质材料晶格常数有所增大，对提高电导率起积极作用；复合添加剂促进了晶粒生长，尤其是含Dy试样晶粒尺寸较大。     

La0．5Sr0．5MnO3纳米晶体的制备与电磁性能研究

以柠檬酸为络合剂，采用溶胶-凝胶（sol—gel）自燃烧方法制备了La0．5Sr0．5MnO3纳米晶体。使用FT-IR，DSC—TG，XRD，波导方法对反应、反应产物以及反应产物的电磁性能进行了研究。结果表明，在凝胶中，金属离子与柠檬酸以络合物的形式存在。凝胶在273℃基本完成自燃烧反应。生成的La0．5Sr0．5MnO3纳米晶体为钙钛矿结构，随着反应温度的提高，产物的粒径逐渐增大。电磁性能结果表明，La0．5Sr0．5MnO3在8GHz～12GHz的微波范围内具有明显的介电损耗。随着厚度的增加，混合媒质的反射率逐渐增加，反射率吸收峰随着厚度的增加向低频移动。     

Mechanism of cathodic delamination control of zinc-aluminum phosphate pigment in waterborne coatings

The propagation of the cathodic delamination and blistering was studied for different waterborne paint systems, with or without the zinc aluminum phosphate (ZAP) pigment. The mechanism by which ZAP reacts at the metal-coating interface to improve coating performance against cathodic delamination and blister formation was investigated by means of scanning acoustic microscopy (SAM), pull-off test and surface analysis. The presence of the pigment clearly enhanced the adhesion and delamination resistance of the coating upon immersion. It has been evidenced how the pH buffer properties of the ZAP pigment play an important role in reducing the advancement of the delamination front. A compact film constituted of zinc and sodium phosphates was found, on the substrate surface, solely within the delaminated area. The precipitation of this phosphate layer on the cathodic sites is thought to polarize the cathodic reaction, contributing to slowing down the delamination reaction.     

De-alloying of type 316 stainless steel in hot, concentrated sodium hydroxide solution

The formation of “nickel” layers on austenitic stainless steel in strong caustic solutions was reported in 1979. We now report a detailed study that clarifies the nature of this de-alloying process and establishes firm links with other metal-environment systems that show de-alloying and associated stress corrosion cracking. De-alloying of iron from 316SS in 50% NaOH at 140 °C proceeds only as far as a solid solution with a Ni/Fe atomic ratio of ca. 1.3 (56 at.% Ni if we neglect the other elements present). Chromium is mostly dissolved and/or reprecipitated during this process. X-ray diffraction shows that the residue is a solid solution of intermediate composition, not a mixture of pure Ni and stainless steel. The removal of only half the iron conveniently explains why the de-alloyed layer is a connected porous network. Electrode capacitance measurements and FEG-SEM examination show that the de-alloyed layer has extremely fine nanoporosity.     

Effects of alloy and solution chemistry on the fracture of passive films on austenitic stainless steel

The Taguchi analysis method was used to simultaneously study the effects of alloy chemistry, pH, and halide ion concentrations on the fracture of electrochemically grown passive films using a nanoindentation technique. Three austenitic stainless steels, 304L, 316L, and 904L were potentiostatically polarized in hydrochloric acid solutions. The fracture load was dominated primarily by alloy chemistry. Passive films mechanically weaken as the atomic iron concentration increases in the film. Prolonged anodic ageing time increases the fracture load of passive films.     

Corrosion resistance properties of glow-discharge nitrided AISI 316L austenitic stainless steel in NaCl solutions

Glow-discharge nitriding treatments can modify the hardness and the corrosion resistance properties of austenitic stainless steels. The modified layer characteristics mainly depend on the treatment temperature. In the present paper the results relative to glow-discharge nitriding treatments carried out on AISI 316L austenitic stainless steel samples at temperatures ranging from 673 to 773 K are reported. Treated and untreated samples were characterized by means of microstructural and morphological analysis, surface microhardness measurements and corrosion tests in NaCl solutions. The electrochemical characterization was carried out by means of linear polarizations, free corrosion potential-time curves and prolonged crevice corrosion tests. Nitriding treatments performed at higher temperatures (>723 K) can largely increase the surface hardness of AISI 316L stainless steel samples, but decrease the corrosion resistance properties due to the CrN precipitation. Nevertheless nitriding treatments performed at lower temperatures (?723 K) avoid a large CrN precipitation and allow to produce modified layers essentially composed by a nitrogen super-saturated austenitic metastable phase (S-phase) that shows high hardness and very high pitting and crevice corrosion resistance; at the same polarization potentials the anodic current density values are reduced up to three orders of magnitude in comparison with untreated samples and no crevice corrosion event can be detected after 60 days of immersion in 10% NaCl solution at 328 K.     

Characteristics and lacquer adhesion on dip and CDC chromium passivated tinplate

Chromium passivation and lacquering are typically used to improve the corrosion resistance of tinplate in packed food. In this work, the nature of the chromium passivation layer formed during dip or CDC passivation treatments, as a function of operational parameters, and its influence on lacquer adhesion, was investigated using electrochemical polarisation, XPS, Auger and lacquer peel-off tests. It was found that dip passivated tinplate provide the best lacquer adhesion, and that the adhesion on CDC treated tinplate could be improved by buffering or lowering the pH of the chromium (VI) solution.     

Determination of corrosion rate of reinforcement with a modulated guard ring electrode; analysis of errors due to lateral current distribution

The main source of errors in measuring the corrosion rate of rebars on site is a non-uniform current distribution between the small counter electrode (CE) on the concrete surface and the large rebar network. Guard ring electrodes (GEs) are used in an attempt to confine the excitation current within a defined area. In order to better understand the functioning of modulated guard ring electrode and to assess its effectiveness in eliminating errors due to lateral spread of current signal from the small CE, measurements of the polarisation resistance performed on a concrete beam have been numerically simulated. Effect of parameters such as rebar corrosion activity, concrete resistivity, concrete cover depth and size of the corroding area on errors in the estimation of polarisation resistance of a single rebar has been examined. The results indicate that modulated GE arrangement fails to confine the lateral spread of the CE current within a constant area. Using the constant diameter of confinement for the calculation of corrosion rate may lead to serious errors when test conditions change. When high corrosion activity of rebar and/or local corrosion occur, the use of the modulated GE confinement may lead to significant underestimation of the corrosion rate.     

The nature of the surface film on steel treated with cerium and lanthanum cinnamate based corrosion inhibitors

The corrosion inhibition mechanisms of new cerium and lanthanum cinnamate based compounds have been investigated through the surface characterisation of the steel exposed to NaCl solution of neutral pH. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to identify the nature of the deposits on the metal surface and demonstrated that after accelerated tests the corrosion product commonly observed on steel (i.e. lepidocrocite, γ-FeOOH) is absent. The cinnamate species were clearly present on the steel surface upon exposure to NaCl solution for short periods and appeared to coordinate through the iron. At longer times the Rare Earth Metal (REM) oxyhydroxide species are proposed to form as identified through the bands in the 1400-1500 cm⁻¹ region. These latter bands have been previously assigned to carbonate species adsorbed onto REM oxyhydroxide surfaces. The protection mechanism appears to involve the adsorption of the REM-cinnamate complex followed by the hydrolysis of the REM to form a barrier oxide on the steel surface.     

Zr57Cu15.4Ni12.6Al10Nb5块体非晶合金晶化行为研究

用示差扫描量热仪（DSC）研究了Zr57Cu15.4Ni12.6Al10Nb5块体非晶合金的匀速升温晶化与等温晶化的晶化行为。在匀速升温晶化方式下，用Kissinger法与Ozawa法获得了块体非晶合金的激活能，对第一晶化峰分别为320．5kJ／mol和316．6kJ／mol，对第二晶化峰分别为324．5kJ／mol和320．5kJ／mol。该非晶合金的晶化表现出明显的动力学效应。在等温晶化方式下，用Johnson-Mehl-Avrami方程获得了晶化的Avrami指数为1．61，表明非晶合金的晶化受原子扩散控制。     

Corrosion behavior of glassy Ni55Co5Nb20Ti10Zr10 alloy in 1 N HCl solution studied by potentiostatic polarization and XPS

Corrosion resistance of glassy Ni₅₅Co₅Nb₂₀Ti₁₀Zr₁₀ (at.%) alloy in 1 N HCl solution was investigated with respect to the electrochemical behavior and the compositions of the passive film and the underlying alloy surface just below the passive film. The potentiostatic polarization curve indicated that the alloy was spontaneously passivated with a low passive current density of the order of 10⁻³ A m⁻². The quantitative X-ray photo-electron spectroscopy (XPS) analysis revealed that the thickness of the surface film increased linearly with an anodizing ratio of 1.5 nm V⁻¹. The high corrosion resistance of the glassy alloy was due to the formation of niobium, titanium and zirconium-enriched passive film. The growth mechanism of the passive films is also discussed.     

Pit-to-crack transition in pre-corroded 7075-T6 aluminum alloy under cyclic loading

Pit-to-crack transition experiments were conducted on 1.600 mm and 4.064 mm 7075-T6 aluminum alloy. Specimens were corroded using a 15:1 ratio of 3.5% NaCl solution and H₂O₂ prior to fatigue loading. Cracks originating from corrosion pits were visually investigated in order to understand how pit-to-crack transitions occur.All prior corroded specimens in the study fractured from cracks associated with pitting. Pit-to-crack transition was successfully acquired visually. Corroded 7075-T6-4.064 mm specimens experienced more of an overall fatigue life reduction than 7075-T6-1.600 mm specimens. Results indicated that quantities such as pit surface area and surrounding pit proximity are as important as pit depth in determining when and where a crack will form.