Ag3PO4溶解热力学函数的晶面效应与温度效应

在室温下制备了立方体{100}、 四面体{111}、 菱形十二面体{110}和块体Ag₃PO₄微晶, 并进行了表征. 测定了其在不同温度下水溶液中的电导率, 结合强电解质溶液和溶解热力学理论, 得到了Ag₃PO₄微晶的溶解热力学函数. 以具有不同晶面的Ag₃PO₄微晶为模型, 研究了纳米材料溶解热力学函数的晶面效应和温度效应. 结果表明, 具有{110}晶面的菱形十二面体Ag₃PO₄的标准摩尔溶解吉布斯自由能()、 标准摩尔溶解焓()和标准摩尔溶解熵()最大, 具有{100}晶面的立方体Ag₃PO₄次之, 具有{111}晶面的四面体Ag₃PO₄最小; 溶解平衡常数(K_{\mathrm{SP}})和随着温度的升高而增大.     

熔盐环境下热障涂层新材料Mg2SiO4的高温腐蚀研究

采用高温固相反应法合成了Mg2 SiO4陶瓷粉末,冷压成型后烧结成陶瓷块材.盐涂法制备V2 O5涂覆的样品,利用马弗炉在950℃空气气氛下保温不同时间.对热腐蚀后的样品进行表面形貌、截面特征的表征,并对Mg2 SiO4的高温熔盐腐蚀机制进行分析研究.结果表明:熔融的V2 O5对Mg2 SiO4陶瓷试样产生两种形式的腐蚀降解作用,即溶解-沉淀机制形成腐蚀产物Mg2 V2 O7和SiO2以及沿晶界腐蚀为主的渗透腐蚀作用.     

过渡层厚度对Be/CuCrZr热等静压连接性能影响

在铍上用物理气相沉积(PVD)镀上10μmTi 和10μmCu，再添加不同厚度的(分别为0.00mm、0.25mm、 0.50mm、0.75mm、1.00mm)无氧铜作为中间过渡层，与CuCrZr/316L(N)复合板基座铜合金侧通过热等静压连接。采用光学显微镜、扫描电镜(SEM)与电子探针(EPMA)、X 射线衍射仪(XRD)、剪切试验等方法确定了界面组织与性能。试验结果表明：各厚度无氧铜模块连接成功，界面无裂纹、空洞等缺陷，钛铜间出现三层明显的反应层，分别为CuTi₂、CuTi 以及Cu₄Ti。添加无氧铜厚度越大，剪切强度越大。     

金催化的硅纳米线的可控制备及光学特性研究

硅纳米线是新型一维半导体纳米材料的典型代表。利用阳极氧化铝薄膜为模版复制出具有有序纳米结构的金膜，在金的催化辅助下对单晶硅进行湿法刻蚀，得到尺寸、形状、分布可控的硅纳米线阵列，并对其光学特性进行了研究。研究结果表明，金代替银作为催化剂，可以有效地抑制二次刻蚀，金的化学性质相对于银更加稳定，克服了银膜在较高的温度或较长刻蚀时间下产生的结构性破坏，得到形貌规整、尺寸可控的硅纳米线阵列。对该阵列在400 nm~1 200 nm波段的反射率、透过率进行了测试，并对比分析了金模板催化与传统方法机理的异同。测试结果表明，相较于传统金属辅助化学刻蚀法，文中提出的金模板催化法制备的硅纳米线阵列尺寸及分布更加均匀可控，在宽光谱范围内的抗反射性得到了显著提高。     

单颗金刚石切削无氧铜的声发射关联维特征*

声发射技术可以实现无氧铜切削加工特征的监测与评价。采用声发射技术监测单颗金刚石磨粒旋转切削无氧铜，利用G-P算法重构出声发射时域信号相空间，采用自相关函数法计算出相空间时间延迟参数，通过相空间双对数曲线的计算，得到不同切削工况下的关联维数。研究结果表明，进给速度和切削速度对声发射信号影响较不显著，切深与声发射信号振幅呈正效应关系；声发射信号双对数曲线呈现阶段性增加趋势，并逐渐收敛于饱和状态，关联维数随着嵌入维数的增加先快速下降后趋于平稳；金刚石切削无氧铜的声发射信号具有混沌运动变化特性，在较小嵌入维数时，关联维数与切深和切削速度呈现线性负效应关系，与进给速度呈现线性正效应关系。该研究为无氧铜的切削加工提供理论参考。     

用三电极体系研究铜在微液滴下的电化学腐蚀

Owing to its high impedance, studying atmospheric corrosion using a traditional reference electrode (RE) is difficult. To obtain more accurate information on the electrochemical processes involved in atmospheric corrosion, it is necessary to improve the traditional RE. In this paper, the corrosion behavior of copper under an electrolyte droplet containing (NH₄)₂SO₄ was investigated by electrochemical impedance spectroscopy (EIS) and polarization measurements using a three-electrode system with a modified RE. The average corrosion rate increased with decreasing electrolyte volumes (from 1 to 20 μL) and with decreasing heights of the droplet at heights below 850 μm. The EIS and polarization results were in agreement, thereby demonstrating that the modified RE could be effectively used to study atmospheric corrosion under an electrolyte droplet.     

常压微等离子体阳极与离子溶液界面的电荷转移反应

Atmospheric- pressure microplasma is an attractive gaseous electrode, and may replace the commonly used rare metal electrodes for electrochemical reactions. The reactions at the plasma anode-liquid interface have not been well investigated, and application of plasma anodes to electrodeposition is still rare. In this communication, by choosing the oxidation of ferrocyanide to ferricyanide as a model reaction, we carefully investigated the charge-transfer reaction at the interface between a plasma anode and an ionic solution. The results showed that ferrocyanide was progressively oxidated to ferricyanide over time, and the rate of oxidation was proportional to the discharge current. We also found that after the discharge the oxidation percent of ferrocyanide still increased approximately linearly with storage time, and the increasing rate was dependent on the discharge time. The rate of oxidation after discharge was much lower than that caused by discharge. These results demonstrate that atmospheric-pressure microplasma could act as a gaseous anode for transferring positive charges at the plasma-liquid interface and inducing electrochemical reactions in solution. During discharge, oxidative active species were also produced. We also successfully electrodeposited copper on stainless steel with the assistance of a microplasma anode in CuSO4 saturated solution, and the current efficiency was about 90%.     

无规共聚物P(MEO2MA-co-OEGMA)的合成及其在水溶液中温度诱导相转变行为

Random copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) and oligo(ethylene glycol) methacrylate (OEGMA, M_n = 500 g·mol^-1) were synthesized by atom transfer radical polymerization (ATRP). Thermally induced aggregation of the co-polymers P(MEO₂MA-co-OEGMA) in aqueous solutions was investigated with dynamic light scattering (DLS), UV-Vis absorption, and transmission electron microscopy (TEM). In addition, the lower critical solution temperature (LCST) in aqueous solutions of P(MEO₂MA-co-OEGMA), and its change with respect to the composition of the copolymer, were obtained. The results indicate that the copolymers have an appreciably reversible thermal responsivity that can be attributed to a delicate balance between hydrogen bonds between the copolymers and water molecules and hydrophobic interactions of polymer segments. If the balance is broken, the polymers attain a new thermodynamic equilibrium by spontaneously changing the extent of aggregation. The LCST correlates linearly with the mole fraction of OEGMA units in the copolymer, and can be adjusted by changing the mole ratio of the two monomers.