H3PO4／H2SO4体系中不锈钢表面膜的XPS分析

采用ＸＰＳ方法研究了两种不锈钢在磷酸体系中的钝化膜。结果表明：不锈钢在不同磷酸介质中形成的钝化膜都由二层所构成，外层为不溶性磷酸盐膜，内层为金属稳定性氧化物。钝化膜内存在Ｃｒ，Ｍｏ的富集和Ｆｅ，Ｎｉ的贫化；同一个介质中不锈钢内任一合金元素的相对量愈高，在钝化膜中也愈高；对同一钢种，介质的组成会影响钝化膜的组成、介质中的ＳＯ＾２－４，Ｆ＾－，Ｃｌ＾－，Ｍｇ＾２＋和Ｃａ＾２＋等，或吸附在钝化膜表面，或     

Intercalation of Graphite in the Ternary Systems C–HNO3–R (R = H2O, CH3COOH, H3PO4 , H2SO4)

The reactions between highly oriented pyrolytic graphite and HNO₃–R (R = H₂O, CH₃COOH, H₃PO₄, H₂SO₄) solutions were studied by x-ray diffraction and potentiometry. The results demonstrate that the nature of component R has a crucial effect on the intercalation process and phase composition of the reaction products. The ability to form ternary graphite intercalation compounds (GICs) depends on the acidity of R. It is shown that CH₃COOH, a weak protic Brönsted acid (pK = 4.76), does not form cointercalation compounds when graphite is treated chemically or electrochemically in HNO₃–CH₃COOH solutions. H₃PO₄, a weak Brönsted acid (pK = 2.12) forms ternary intercalation compounds. Stage II–IV ternary GICs with HNO₃ and H₃PO₄ (d _i = 8.05 Å) were for the first time synthesized and investigated. H₂SO₄, a strong Brönsted acid (pK = –2.8), forms stage I cointercalation compounds (I _c = 8.02 Å), independent of the HNO₃ content (5–95 wt %) of the oxidizing mixture. The potential of the HNO₃–H₂SO₄ solutions was found to be E _Ag/AgCl = 1.39 V, independent of the HNO₃ : H₂SO₄ ratio. The main relationships in the ternary systems were shown to be similar to those for the formation of binary GICs with acids. There is a perfect correlation between the redox potential of the HNO₃–R (R = H₂O, CH₃COOH, H₃PO₄, H₂SO₄) solutions and the stage index of the resulting GIC. The concentration ranges of GIC formation in nonaqueous HNO₃ solutions were extended substantially. The behavior of stage I–IV graphite nitrates in different solvents (H₂O, CH₃COOH, H₃PO₄, and H₂SO₄) was studied. Based on the experimental results, mechanisms of the processes in the systems studied were proposed.     

Synthesis of Ternary Intercalation Compounds in the Graphite–HNO3–R (R = H2SO4 , H3PO4 , CH3COOH) Systems

The reactions of stage II–IV graphite nitrates with concentrated H₂SO₄, H₃PO₄, and CH₃COOH were studied at graphite : acid weight ratios from 3 : 1 to 1 : 1. The results demonstrate that the reactions in question follow different paths. In the graphite nitrate–H₂SO₄system, the reaction decreases the stage index and yields a ternary graphite intercalation compound. The contents of intercalated HNO₃and H₂SO₄are controlled by the amount of H₂SO₄and the stage index of the parent graphite nitrate. The reaction between graphite nitrate and H₃PO₄leads to partial replacement of HNO₃by H₃PO₄, increasing the identity period without changes in the stage index. The results for the graphite nitrate–CH₃COOH system provide no direct evidence for the formation of an intercalation compound with HNO₃and CH₃COOH. It is shown that varying the nature and amount of the second intercalate species opens up possibilities for preparing oxidized graphite with controlled physicochemical properties.     

Al(H2PO4)3/Al2O3复合硬质材料吸湿改性研究

磷酸二氢铝、磷酸铬铝等无机材料作为高温粘结剂具有固化收缩率低、高强度、耐高温等优点,被广泛应用于冶金、化工以及航天航空领域,但其可吸收空气中的水蒸汽,从而降低材料的强度和完整性.为减少无机高温粘结剂在大气环境下的吸湿量,以有机聚合物聚醚砜、无机添加剂氧化锆粉、热辐射屏蔽剂金粉制备出一种具有耐高温、低导热、热辐射屏蔽的复合密封材料,并将其应用在Al(H2PO4)3/Al2O3复合硬质材料的吸湿改性中.通过对比改性前后样品的扫描电镜图、吸湿率曲线,测试复合密封材料对基体材料吸湿性能的改性效果,并为研究喷涂密封材料对基体材料隔热、强度等性能的影响,进一步分析改性前后样品导热系数、弯曲强度的变化.结果表明,聚醚砜可在基体材料表面形成致密的密封膜,不仅可以隔绝空气中的水蒸汽,使吸湿率最高下降68.39％,还可以提升材料的弯曲强度.同时,金粉的添加可以形成辐射屏蔽层,从而降低材料的高温热导率.     

Graphite Intercalation in H2SO4–CH3COOH Electrolytes

The anodic oxidation of highly oriented pyrolytic graphite in H₂SO₄–CH₃COOH electrolytes in a galvanostatic mode (I = 1.5 mA) is studied as a function of electrolyte composition. The concentration ranges for the formation of stage I–V graphite intercalation compounds (GICs) are determined. The concentration threshold for intercalation is 1 wt % H₂SO₄. There are three distinct concentration ranges differing in the shape of the charging curve E(Q), which depends primarily on the content of H₂SO₄ (active intercalant). The potentials of formation of stage I–III GICs in H₂SO₄–CH₃COOH electrolytes are found to be higher than those for graphite bisulfate, which points to an increase in the potential barrier for intercalation and is obviously associated with the intercalation of acetic acid into the graphite host. The specifics of the charging curves obtained in 60–80% H₂SO₄, together with gravimetry and chemical analysis data, indicate the formation of ternary GICs with sulfuric and acetic acids. In this composition range, stage I* and II* cointercalation compounds are obtained, with an intercalate layer thickness d _i = 7.94 Å. The composition of the ternary GICs is shown to depend on the relative amounts of the acids in the electrolyte. A mechanism of the formation of graphite cointercalation compounds is proposed. In solutions containing less than 40 wt % H₂SO₄, only graphite bisulfate is formed.     

InGaAs／InAlAs异质结的H3PO4／H2O2系的湿法腐蚀

采用了H3PO4/H2O2系化学腐蚀液对GSMBE外延的InGaAs/InP和InAIAs/InP材料湿法腐蚀特性进行了研究,研究了不同浓度和配比对于腐蚀速率和形貌影响.结果表明该腐蚀液体系具有良好的均匀性,腐蚀速率随浓度呈指数关系,表面形貌基本不受浓度影响.在增加腐蚀液中双氧水含量时,腐蚀速率先增大后减小,表面形貌良好;增加磷酸浓度腐蚀速率亦有增大趋势,表面出现尖锥状小丘.并对腐蚀液配比变化对腐蚀特性影响及腐蚀机理进行了讨论分析.     

Intercalation of nitrogenous substances into HUO2PO4·4H2O

The laminar compound HUO₂PO₄·4H₂O (HUP) interacts with piperidine, hydrazine, pyridine, pyrazine and (dimethylamino-methyl)ferrocene to produce intercalation reactions. The intercalate materials exhibit a layered structure derived from the starting solid. The only observed structural modifications were dimensional changes in the crystal c axes.The amount of adsorbate taken up by the HUP is related to the size and geometry of the guest molecule and its basicity. The guest-host reactions are of the acid-base type as shown by i.r. spectra.     

CH4—C2H6—C3H8和N2—CH4—C3H8三元混合物汽—液相平衡

对含有N_2、CH_4、C_2H_0和C_3H_8的混合物体系的相平衡、热力学性质进行了实验研究,并对其热力学关联式的精度进行了检验。本文报告了压力在20～120巴和温度个在200K条件下三元体系的许多T-p-x-y实验结果,并与由普遍化状态方程计算的结果作了比较。     

基于Na3Zr2Si2PO12固体电解质的非平衡态SO2传感器

基于Na₃Zr₂Si₂PO₁₂(NASICON)固体电解质, 分别以Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂复盐为敏感电极材料制备了片式SO₂非平衡态气体传感器。结果表明, 该类型传感器的输出电动势与SO₂气体浓度的对数呈良好的线性关系, 在低温260℃具有最佳性能, 灵敏度分别达到了160 mV/decade和136 mV/decade。传感器在不同浓度的SO₂气体中的交流阻抗谱测试结果显示, 气体在敏感电极的三相界面处电化学反应的活性随着气体浓度的增大而增强, 结合敏感电极结构, 对该类敏感电极的机理进行了分析。由于NASICON具有良好的低温钠离子导电性, 可以大幅降低传感器的工作温度; 由于Na₂SO₄-BaSO₄混合盐和NaRe(SO₄)₂敏感材料具有更好的化学稳定性, 制备的传感器具有良好的可重复性和稳定性。基于非平衡态设计的传感器, 具有结构简单和成本低的优点。以上特性为该传感器在SO₂气体在环境监测方面的应用提供了可能。     

离子色谱法测定地下水中的六种阴离子——F^-、CI^-、NO2^-、H2PO4^-、NO3^-、SO4^2-

本文利用离子色谱法成功的测定了地下水中的F^-、CI^-、NO2^-、H2PO4^-、NO3^-、SO4^2-六种阴离子,大大降低了干扰因素的影响,提高了结果的准确度,缩短了分析时间,提高了工作效率。该方法加标回收达到93～104％之间,精密度相对偏差小于3％。     

棱角对NH4H2PO4晶体Z切片薄表面层生长影响的研究

本研究制备了具有不同形式棱角的NH₄H₂PO₄(ADP)晶体Z切片样品。通过实验, 观察不同Z切片薄表面层形成及生长特性, 并计算了不同棱角情况下薄表面层的切向生长速度V及其动力学系数β。结果表明, 正常棱角的缺失, 影响Z切片对其原有形态的“判断”, 进而影响薄表面层的形成及生长; 薄表面层在正常棱角处相遇形成相交角后, 将主要在相交角处形成并向棱边扩展生长, 表明棱角可能为薄表面层的主要生长源。此外, 计算结果显示, 正常棱角处薄表面层切向生长的平均生长动力学系数β_n为131.8 μm/s, 远大于棱角缺失后薄表面层切向生长的平均生长动力学系数β_a=11.6 μm/s, 即正常棱角缺失后, 薄表面层的切向生长速度将大大降低。     

Ceramics Based on CaSO4⋅2H2O Powder Synthesized from Ca(NO3)2 and (NH4)2SO4

Inorganic Materials - Ceramics consisting of anhydrous calcium sulfate, CaSO4, after firing in the range 800–1000°C have been prepared from calcium sulfate dihydrate (CaSO4?2H2O)...     

Studies of Ion-Transport Mechanisms in PEM Based on PVA ＋ H3PO2 ＋ H2O

The ionic conductivity for proton exchange membranes （PEM）, based on the PVA ＋ H3PO2 ＋ H2O polymer system was studied as a function of temperature. The dc-conductivity of all compositions increases rapidly with the acid concentration, between 10.3 and 101 S·cm^-1as the acid concentration was increased. Hydrated membranes showed an Arrhenius-type behavior in their conductivities, with an activation energy between 0.20 and 0.10 eV as the acid concentration was increased. When the relative humidity varies between 25% and 92% at room temperature, water uptake increases dc-ionic conductivity varying between 10-3 and 10-2 S·cm^-1 for the best performing composition （P/OH = 0.3）. The plot of the conductance of the polymer electrolyte as a function of % RH follows a sigmoidal trend. This functional variation was found to be strictly correlated with a similar trend of the film capacitance through a relationship derived from the Onsager equation for liquid electrolytes. Thus, the results support the presence of a （H3PO2/H2O） separated liquid phase in the polymer.     

First principles study of isotope effect in hydrogen-bonded K3H(SO4)2: I — stable structures

The first principles calculations for K₃H(SO₄)₂ (KHS) system are performed in order to determine its stable structure in the presence of the hydrogen or the deuterium in its hydrogen bond, and to discuss the origin of the large isotope effect in the KHS system. As a result, a reasonable value of the antiferroelectric interaction energy is obtained. It is also found that the position of the hydrogen is closer to the center of the hydrogen bond than that of the deuterium, based on the calculated results of the proton-position dependence of the oxygen–oxygen distance and on the experimental fact that the oxygen-oxygen distance in K₃D(SO₄)₂ (DKHS) is larger than that in KHS.     

Synthesis of Intercalation Compounds in the Graphite–HNO3–H3PO4System

The highly oriented pyrolytic graphite–HNO₃–H₃PO₄system was studied by x-ray diffraction and potentiometry at different acid concentrations. The results demonstrate that chemical and electrochemical intercalation in the graphite–98% HNO₃–85% H₃PO₄system yields graphite nitrate, a binary graphite intercalation compound (GIC). H₃PO₄is shown to have an ambiguous effect on the concentration ranges of different stages of graphite nitrate, shifting them to lower HNO₃concentrations as compared to the graphite–HNO₃–H₂O system. In the graphite–98% HNO₃–100% H₃PO₄system, a stage II ternary GIC is obtained, with an intercalate layer thickness d _i 4.7 Å. Stages II–VI of this GIC were prepared via exchange reaction between graphite nitrate and 100% H₃PO₄. A mechanism for the formation of the ternary GIC is proposed. The synthesis of the cointercalated GIC is likely to involve two steps: in the first step, graphite nitrate is formed; subsequent reaction in the intercalate layer leads to partial replacement of solvated HNO₃by H₃PO₄molecules.