热水器搪瓷表面银离子扩散工艺研究

对通过浸渍法,在一定温度下的热水器搪瓷表面进行银离子扩散的工艺进行了研究。研究结果表明,采用该工艺在搪瓷表面进行银离子扩散是可行的,且银离子的扩散分布均匀。当扩散时间较长时,银离子扩散进搪瓷表面的量也相对较多。同时,银离子的扩散会对搪瓷原来的性能产生一定的影响。     

某核电站行车轨道用U71Mn钢的焊接及热处理工艺研究

本文对U71Mn轨道钢焊接及热处理工艺进行了研究。编制了第一次焊接工艺评定方案,结果表明,该方案下轨道焊缝产生多处裂纹,不符合要求。分析认为,U71Mn钢的焊接接头处应力较大,焊缝室温下组织为高碳片状马氏体,具有高强度、高硬度的特点,焊接性较差。第一次焊接工艺评定中预热温度过低、焊后热处理的时间过短,在应力、扩散氢等因素作用下极易扩展形成冷裂纹。为此,在第二次工艺评定方案中,提高预热温度及恒温时间、增加焊后热处理的时间,细化组织晶粒,改善了接头的应力且有利于焊缝中氢的扩散逸出。结果表明,在工艺改进后,焊缝表面未出现裂纹。     

等离子热喷涂涂搪工艺技术研究

简要介绍了等离子热喷涂技术原理、特点和作用,研究了适合热喷涂工艺技术的搪瓷瓷釉和喷涂搪瓷粉末,以及适合釉料喷涂的热喷涂工艺技术参数。研究结果表明,在厚钢板表面,采用特殊的瓷釉粉末,通过热喷涂技术可以进行搪瓷表面的喷涂,该工艺特别适合于大型搪瓷设备的表面涂搪。     

铝锌镀层钢板搪瓷烧成工艺的探讨

将铝锌镀层钢板搪瓷在一定温度下不同时间烧成,通过金相、扫描电镜和能谱仪对样品横切面进行分析,探讨不同的烧成工艺对搪瓷烧成结果的影响。     

离子交换法在钠钙硅酸盐玻璃中原位合成银纳米颗粒的研究

采用离子交换结合热处理法,在商用钠钙硅酸盐平板玻璃中原位形成2～7nm的银纳米颗粒。利用电子探针、X射线吸收近边结构谱、透射电子显微镜和高分辨透射电子显微镜研究了银离子在玻璃中的扩散、还原和生长机理。结果表明：玻璃中同时存在2价和3价铁离子,2价铁离子的存在有利于银离子被还原成中性银原子。银原子在玻璃中成核并生长成纳米颗粒。银纳米颗粒可以在离子交换时形成。提高热处理温度比延长热处理时间更有利于颗粒长大。特别当热处理温度高于玻璃转变温度时,出现Ostwald生长,导致银颗粒迅速长大,密度降低。大部分银纳米颗粒为十四面体单晶,少量为孪晶结构。     

TiO2薄膜纳米改性搪瓷表面光泽影响的研究

采用溶胶-凝胶法制得稳定的淡黄色透明TiO2溶胶溶液,通过浸渍提拉法在搪瓷表面制备TiO2薄膜。研究了在搪瓷表面涂有不同层数的TiO2薄膜对其光泽度的影响,同时还采用XRD和SEM分析了搪瓷表面TiO2薄膜的晶体结构和显微形貌。结果表明,薄膜在400℃热处理1 h后,具有完整的锐钛矿相和良好的光学性能;不同层数的TiO2薄膜对搪瓷表面的光泽度产生了显著的影响。     

E-Brite50/50无氰镀银工艺工程化应用

从工程化应用角度考虑,对E-Brite 50/50无氰镀银工艺的相关性能进行考察。确定了批量生产过程的电流密度、镀液温度、pH等工艺参数,研究了镀液均镀能力、施镀过程中银离子含量变化和阳极钝化等情况,表征了镀层的附着力、耐蚀性、可焊性、表面形貌等性能。结果表明,E-Brite50/50无氰镀银工艺镀液稳定,有一定的工程化应用价值。但与氰化镀银相比,该工艺的电流密度范围窄,均镀能力较差。     

TiO2薄膜纳米改性搪瓷表面光泽影响的研究

采用溶胶-凝胶法制得稳定的淡黄色透明TiO2溶胶溶液,通过浸渍提拉法在搪瓷表面制备TiO2薄膜。研究了在搪瓷表面涂有不同层数的TiO2薄膜对其光泽度的影响,同时还采用XRD和SEM分析了搪瓷表面TiO2薄膜的晶体结构和显微形貌。结果表明,薄膜在400℃热处理1 h后,具有完整的锐钛矿相和良好的光学性能;不同层数的TiO...     

覆铝钢板搪瓷的底材化学处理

研究了覆铝钢板复合材料的表面化学状态与搪瓷密着性的关系,认为表面的组织状态与结构对搪瓷密着性有很大的影响。实验得出,铬浴处理后的覆铝钢板表面活性强,组织结构适合瓷釉元素的扩散,搪瓷界面过渡层宽度增加,密着强度提高。     

SiO_2/ZnO复合薄膜改性及二甲基二氯硅烷修饰的搪瓷表面疏水性能研究

采用水热法,通过反应釜中高温高压在搪瓷表面制备了SiO_2/ZnO复合薄膜。研究了不同反应温度、水热时间与溶胶配比对其疏水性能的影响。利用SEM、红外光谱仪、全自动视频微观接触角测量仪分析了薄膜的微观结构与性能,最后对搪瓷表面进行光泽度、白度、耐酸度的测试。结果表明,反应温度在220℃,水热时间为14 h,SiO_2溶胶与ZnO溶液配比为1∶1时制备的SiO_2/ZnO复合薄膜,经过DDS修饰疏水性能最优,接触角达到150.3°。SiO_2/ZnO复合薄膜对搪瓷的光泽度与白度基本没有影响,不影响表面实际观感,同时搪瓷表面耐酸性为一级。     

Evaluation of Microstructure Characteristics of Lithium Niobate Single-Crystal Fiber with Magnesium-Ion-Indiffused Cladding

A magnesium ion indiffusion process is applied to lithium niobate single–crystal fibers. Electron probe microanalysis shows that magnesium ions have diffused into the bulk of the crystal fibers and the magnesium ion concentration in the magnesium–diffused layer has an approximately parabolic profile, which corresponds to that of theoretical simulation. It is shown by conventional X–ray diffraction and scanning electron microscopy that a good starting single crystal of the magnesium–diffused crystal fiber can be preserved by controlling suitable diffusion parameters such as diffusion temperature, diffusion time, and MgO film thickness, etc., to ensure the completeness of magnesium ion indiffusion, but the magnesium–diffused region etches differently from virgin-region crystals.     

Effect of microwave sintering on the microstructure and electric properties of (Zn,Mg)TiO3-based multilayer ceramic capacitors

In this study, the effects of microwave sintering on the sintering behaviour, microstructure and silver diffusion of (Zn,Mg)TiO₃-based multilayer ceramic capacitors (ZMT MLCCs) with pure silver electrodes were investigated. The energy dispersive spectroscopy results showed that the silver ions diffused into the dielectric layer significantly when the ZMT MLCC was sintered with conventional processing at 900 °C. However, sintering of ZMT MLCC at 900 °C using microwave processing was found to effectively suppress silver ion diffusion into the dielectric layer. The concentration of silver ions was identified by wavelength dispersive spectroscopy, which showed that the Ag ion concentrations for conventional and microwave sintering are approximately 1.0 at.% and below 0.4 at.%, respectively. The observed difference may be due to different kinetics between conventional and microwave sintering.     

Suppression of Silver Diffusion in Borosilicate Glass‐Based Low‐Temperature Cofired Ceramics by Copper Oxide Addition

The silver diffusion behavior in the low‐temperature cofired ceramic (LTCC) comprising of borosilicate glass and alumina was investigated in this work. Transmission electron microscope (TEM) analysis revealed that silver ions diffused into LTCC materials through the glass phase. The addition of copper oxide in the LTCC materials can suppress the silver diffusion during the sintering process because of the enhanced crystallization of borosilicate glass, which leads to the quick increase in glass viscosity and retards the silver diffusion. Thermal dynamic analysis confirmed that the diffusion coefficient of silver in the copper‐oxide‐modified LTCC materials was largely reduced.     

载纳米银蛭石的制备和表征及其抗菌性能

本文以新疆蛭石为原料,通过对蛭石进行酸化、热及钠化处理后,在室温下采用离子交换法制备了载纳米银蛭石.用红外光谱、X射线衍射、原子吸收光谱和扫描电子显微镜对载纳米银蛭石进行了分析表征,结果表明:载纳米银蛭石的红外吸收谱与前躯体基本相同,金属纳米银颗粒较为均匀地负载在蛭石的表面,载纳米银蛭石的载银量为3.33%.用大肠杆菌和金黄色葡萄球菌进行抗菌实验表明,载纳米银蛭石具有很强的抗菌性能.     

扩镁铌酸锂单晶光纤的微观结构分析

通过电子探针显微分析表明，铌酸锂单昌光纤经镁离子的内扩散后，镁离子已完全扩散进晶纤内部，且扩散层镁离子浓度呈现抛物线形分布。通过常规Ｘ射线衍射的ＬａｕｅＸ射线衍射照相证明：铌酸锂单晶光纤并不因镁离子的进入百破坏其晶体特性，而是保持了完好的单晶结构。     

银离子抗菌聚己内酰胺纤维的研制及开发

主要介绍银离子抗菌聚己内酰胺纤维的制造方法、设备、原料及纺丝工艺。如抗菌母粒的选择,纺丝温度,纺丝组件,纺丝油剂及上油率,卷绕速度。采用高速纺丝法工艺路线成功开发出银离子抗菌聚酰胺纤维。     

不同Br~-浓度下铂电极上镀银层的氧化动力学

本文采用循环伏安法研究了镀银铂电极在溴化钾溶液中的成核过程及氧化动力学,结果表明:AgBr的形成包括三个步骤,首先在银表面某些吸附Br~-的特殊位置上以平面方式成核,然后经过二个三维的成核步骤。在较低浓度的KBr溶液中,AgBr的形成由溶液中的Br~-迁移控制。在较高浓度的溶液中,由于生成的AgBr膜是高度松散的,速度控制步骤转化为在膜孔内Br~-的迁移。随着AgBr的生成以及AgBr的溶解沉积作用,膜孔被堵塞,同时反应速度转化为由AgBr膜中的Ag~+迁移控制。电镜结果也支持了以上结论。     

Selective silver ion adsorption onto mesoporous graphitic carbon nitride

A 3D cubic structure of mesoporous graphitic carbon nitride (3D-g-CN) was fabricated by nano casting using the mesoporous silica hard template KIT-6. The abundant intrinsic amine functionalities of 3D-g-CN were applied as a selective adsorbent for silver ions using the unique affinity of silver and amine functionalities. The large surface area of 3D-g-CN resulted in increased amine functionalities at the surface and enabled it to form complexes with silver ions. As a result, almost 400 mg/g of silver ion could be removed from 100 mM of initial solution at 293.15 K. The isotherm of silver ion adsorption onto 3D-g-CN was described by the Freundlich and Sips models and indicated heterogeneity of the adsorbent surface. Thermodynamic parameters determined from temperature dependent isotherms were verified by the endothermic silver ion adsorption process of 3D-g-CN. The adsorption capacity of silver ion on 3D-g-CN was maintained during several reuses without a significant decrease in capacity. Overall, the results indicate that 3D-g-CN has intrinsic amine functional groups with a large surface area and could therefore be utilized as an efficient selective adsorbent of silver ions for water purification.     

On the calculation of potential energy profile diagrams for processes in electrolytic metal deposition

The calculation of potential energy and free energy profile diagrams for successive and alternative steps in electrolytic metal deposition is described with reference to two extreme models of the entity resulting from the initial transfer of the metal particle from the solution to the surface of the metal.

Neutralization of the transferred ions to form adsorbed metal atoms is distinguished from ion-transfer processes in which the transferred entity maintains ionic character, with the appropriate number of stoichiometric electrons entering the metal lattice for each ion transferred.

The elementary processes considered are: transfer of ions from the solution to different types of surface sites upon the metal; surface diffusion of adsorbed ions; successive, dehydration of the adsorbed ions in lattice building.

The free energies of the transition states in successive steps in consecutive ion-transfer, surface-diffusion and lattice-building reactions are compared, and the probable rate-determining process in the over-all metal deposition reaction is deduced in the cases of Cu²⁺, Ni²⁺ and Ag⁺ ion deposition on to the respective metals. Uncertainties in the calculation are examined.

The heat of activation (ΔH^0≠) for transfer of ions from the solution to the metal surface depends upon the site to which transfer occurs, that to a planar site being significantly less than that to other sites (e.g., edges, kinks, etc.) Transfer to form completely non-polar neutral adatoms has prohibitively high values of ΔH^0≠

Direct deposition Of Cu²⁺ on to surface sites would be associated with a prohibitively high heat of activation. The path Cu²⁺ + e_M → Cu⁺ followed by Cu⁺ + e_M → (Cu_adion⁺+ e_M) is associated with heats of activation significantly lower than that for direct Cu²⁺ deposition in a single two-electron step. The free energy diagrams are consistent with the existence of a rate-determining reduction mechanism found experimentally. Near the Cu/Cu²⁺ reversible potential the free energy barrier for adion surface diffusion can become the highest. This is consistent with the experimental behaviour under these conditions. With Ag⁺ ion deposition the ion-transfer step has the highest free energy barrier at high negative overpotentials, whilst near the reversible potential the barrier for surface diffusion can become the highest. The kinetic behaviour found experimentally with silver supports the theoretical conclusions.

The low exchange current density for Ni²⁺ ion deposition is probably associated with the instability of the simple Ni⁺ ion in aqueous solutions.     

Antibacterial Thin Films on Glass Substrate by Sol–Gel Process

Antibacterial transparent thin films, containing different amounts of silver ion, have been prepared on a glass substrate by the sol–gel process. Thin films were obtained from inorganic-organic hybrid sols derived from 3-(glicydiloxypropyl)trimethoxy silane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane and aluminium-sec-butoxide/ethylaceto-acetate complex and doped with silver ions. The films were characterized by Scanning Electron Microscopy and Raman Spectroscopy. The physical properties of the films were studied by solar-box, taber abraser, hardness test pencil, scratch-adhesion test and spectroscopy. The antibacterial activity of the coatings were investigated against gram negative Escherichia coli and gram positive Staphylococcus aureus. The results showed that 1% doping of the transparent hybrid thin film with silver ions resulted in high antibacterial properties of the film.