Exploring the Friction and Wear Properties of Silver Coatings on 718 Alloy

Fasteners of 718 alloys are used to set up connection between each support and other components for ITER system, metal-based Ag solid lubricant coating is widely used as an anti-seizure lubricant coating due to its strong low-temperature shear resistance. But the poor adhesion to the steel surfaces has been a critical restriction for applying the silver coatings to the practical machine elements. In this work, an 8-μm silver self-lubricating coating was deposited on the surface of 718 alloy by the method of magnetron sputtering. The coating was uniform, dense and consistent. The wear mechanism was investigated by analyzing the friction and wear properties of the coating. Stress is one of the important impacts on the friction coefficient, the results showed that it first increased and then decreased with the increase of pressure at room temperature and under vacuum. Temperature exerted an effect on the silver self-lubricating coating. A study was conducted under vacuum on the friction and wear performance of the coating at 300 K, 225 K, 155 K, and 77 K, respectively. The results showed that the wear mechanism and wear state varied under various low-temperature conditions, with the severity of wear reaching the maximum only at 225 K. Through the same silver coating process, the washer of superbolt was improved by silver coating treatment.

Evaluation of Novel Chitosan Based Composites Coating on Wettability for Pure Titanium Implants

This work aims to prepare chitosan(CS)-based coated layers,CS(10 wt%nanosilver/90 wt%CS,10 wt%biotin/90 wt%CS,and 5 wt%nanosilver–5 wt%biotin)/90 wt%CS coatings are prepared,onto pure Ti substrate.The surface morphology of the novel CS composite coating was studied using field emission scanning electron microscopy,atomic force microscopy(AFM),Fourier transforms infrared(FTIR)and wettability test.Results show that the addition of(biotin,nanosilver)5 Vol.%improves the properties of composite materials.Using different particles’scale size aid in improving the combinations in the alginate,producing a dual effect on film properties.Coating surface roughness decreased in the chitosan-based biocomposite with preferable homogeneity and crack-free coating layers,as confirmed by AFM.An increase in surface roughness ensured substitution,which enhanced the surface structures.The high wettability of the CS-based coating layers was due to the presence of nanoparticles,and the composite coatings with CS,nanosilver,or biotin had excellent wettability because of the good hydrophilic nature of the CS matrix combined with reinforced particles.The FTIR results showed that peaks of the blending of CS plus nanoparticles,CS plus biotin,or CS plus nanosilver plus biotin were excellent matching with no changes in the structure of the matrix.

One-step electrodeposition to fabricate robust superhydrophobic silver/graphene coatings with excellent stability

A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics.Silver coating was firstly deposited on thermoplastic polyurethane(TPU)elastomer rubber surface via two-component spraying technique,then the superhydrophobic surface was obtained by one-step electrodeposition of cerium compounds(CeM)and graphene nanosheets(GNS)to produce Ag/CeM/GNS composite coatings.The obtained Ag/CeM/GNS composite coatings maintained high conductivity after experiencing bending cycles and stretching cycles.Furthermore,the as-prepared Ag/CeM/GNS composite coatings showed excellent self-cleaning and anti-fouling properties,and the corrosion resistance has improved significantly compared to the original Ag coating.In addition,the Ag/CeM/GNS composite coatings could drive the circuit normally in the states of tensile,bending and twisting deformation,showing excellent mechanical stability and applicability.As a result,it is believed that the prepared Ag/CeM/GNS composite coatings with excellent conductivity and stability have promising applications for flexible electronics in harsh conditions.

Acid/Base Treatment of Monolithic Activated Carbon for Coating Silver with Tunable Morphology

Silver coatings on the exterior surface of monolithic activated carbon（MAC） with different morphology were prepared by directly immersing MAC into [Ag（NH3）2]NO3 solution. Acid and base treatments were employed to modify the surface oxygenic groups of MAC, respectively. The MACs＇ Brunauer-EmmettTeller（BET） surface area, surface groups, and silver coating morphology were characterized by N2 adsorption, elemental analysis（EA）, X-ray photoelectron spectroscopy（XPS）, and scanning electron microscopy（SEM）, respectively. The coating morphology was found to be closely related to the surface area and surface functional groups of MAC. For a raw MAC which contained a variety of oxygenic groups, HNO3 treatment enhanced the relative amount of highly oxidized groups such as carboxyl and carbonates, which disfavored the deposition of silver particles. By contrast, Na OH treatment significantly improved the amount of carbonyl groups, which in turn improved the deposition amount of silver. Importantly, lamella silver was produced on raw MAC while Na OH treatment resulted in granular particles because of the capping effect of carbonyl groups. At appropriate [Ag（NH3）2]NO3 concentrations, silver nanoparticles smaller than 100 nm were homogeneously dispersed on Na OH-treated MAC. The successful tuning of the size and morphology of silver coatings on MAC is promising for novel applications in air purification and for antibacterial or aesthetic purposes.

Preparation and Characterization of Poly(melamine-urea-formaldehyde) Tetradecanol Microcapsules Coated with Silver Particles

A novel type of microencapsulated phase change materials(microPCMs)based on 1-tetradecanol(TD)core and silver-coated poly(melamine-urea-formaldehyde)(MUF)shell was successfully synthesized by in situ polymerization method followed by silver reduction.Fourier-transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),scanning electron microscopy with energy dispersive X-ray spectrometry(SEM/EDS),thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)were used to characterize the chemical structure,morphology and thermal properties of the as-prepared silver-coated microPCMs.FTIR analysis confirmed the successful encapsulation of TD with MUF wall materials.The SEM and EDS results indicated that the prepared silver-coated MUF microPCMs exhibited uniform spherical shape with a perfect silver outer layer.From XRD analysis,the Ag metal dispersed on the surface of microcapsules presented the form of elementary substance.The deposition weight of silver particles on the microcapsule surface increased with increasing the amount of silver nitrate,as indicated by EDS tests.The DSC results indicated that the melting temperature and the melting latent heat of microPCMs modified with 0.7g of silver nitrate in 150mL aqueous solution were 39.2°C and 126.6J·g^-1,respectively.Supercooling of the microPCMs coated with silver particles was effectively suppressed,compared with that of microPCMs without Ag.Thus,the encapsulation of TD with silver-coated MUF shell developed by this work can be an effective method to prepare the microPCMs with enhanced thermal transfer performance and phase change properties.

Structure, properties and application to water-soluble coatings of complex antimicrobial agent Ag-carboxymethyl chitosan-thiabendazole

The structure, properties and application to water-soluble coatings of a new complex antimicrobial agent Ag-carboxylmethyl citosan-thiabendazole （Ag-CMCTS-TBZ） prepared from different materiel ratios were reported. The silver ions were preferably coordinated with the free-NH2 groups and the -OH groups of secondary alcohol and carboxyl in CMCTS. TBZ preferably bonded to carboxyl group in CMCTS by electrostatic force and hydrogen bonding. Increase in silver ions content in the complex agent improved to some limited extent the antibacterial activity, but enhanced coloring and cost of the complex agent. Increase in TBZ content resulted in increase of antifungal activity, but decrease of water solubility of the complex agent. The antimicrobial MICs of the complex agent to Esherichia coil, Staphylococcus aureus, Candida albicans, Aspergillus niger, Mucor sp. were 20 -80, 15 -60, 20 - 55, 40 - 250, and 400 - 1700 mg/kg, respectively. Addition of 0.1% of this complex agent to acrylic emulsion paint made the paint without substantial change in color, luster, viscosity, odor or pH value, but with an excellent and chronically persisting broad-spectra antimicrobial activity.

Fabrication of Large-area 3-D Ordered Silvercoated Colloidal Crystals and Macroporous Silver Films Using Polystyrene Templates

The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.

CATALYTIC REDUCTION OF HEMOGLOBIN AT PHENOTHIAZINE COATED SILVER ELECTRODE

Phenothiazine-coated silver electrode prepared by a simple reaction of phenothiazine with the metal is very stable and can make the reduction of hemoglobin possible.

电感耦合等离子体发射光谱(ICP-OES)法测定含碘附银硅胶样品中碘含量

附银硅胶可以吸附放射性碘,形成含碘的附银硅胶,是后处理厂中常用的碘废物吸附材料。含碘附银硅胶样品中碘含量的准确测定能够验证碘的吸附效率,为后处理过程提供数据支持。含碘附银硅胶样品中银离子和碘离子形成难溶的碘化银,在溶解过程中难以将碘化银中碘离子定量转化为可溶解的碘离子、碘单质或者碘酸根,因此含碘附银硅胶样品中碘含量的测试方法比较困难。通过查阅银化合物的溶度积常数,考虑掩蔽银离子对碘离子的影响,在实验中采用加入硫离子的方法,生成比碘化银更难溶的硫化银沉淀,从而消除银离子的干扰。置换出的碘离子能够在碱性溶液中稳定存在,因碘含量较高,可采用电感耦合等离子体发射光谱法(ICP-OES)测定其含量。实验过程中考察了硫化钠加入量、氨水浓度、超声时间等对结果的影响。结果表明,硫化钠加入量与样品中银的含量有关,需要加入过量的硫离子沉淀银离子,不同的氨水浓度影响碘的灵敏度,而超声时间对结果基本无影响,优化实验条件后得到方法的检出限为0.52 mg/g,分别测量两个不同含量的含碘附银硅胶样品,平均值(n=6)为34.8 mg/g和59.3 mg/g,相对标准偏差为2.7%和2.0%,加标回收率为95.0%~103%。方法能够满足含碘附银硅胶样品中碘含量的测定。

银铜侧向复合材料界面结合机理分析

本文采用“包覆锭坯+扩散烧结+冷轧复合”联合工艺制备了银铜侧向复合带材,利用金相显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)观察分析银铜复合界面结构和元素分布,并分析其银铜复合界面的结合机理。结果表明,银铜复合界面形成过程为:1)银铜接触界面处凹凸不平的表面在轧制力的作用下相互咬合,形成机械结合界面;2)接触面在轧制力的作用下,银铜表面氧化膜破裂,新鲜表面质点间在轧制变形热的作用下产生原子结合;3)在扩散烧结过程中,银铜界面处的原子在高温作用下被激活,银铜原子相互扩散,在界面处发生银铜共晶反应形成液相金属层,随着烧结时间的延长,其共晶反应液相层厚度逐渐增加,随后冷凝结晶,使银铜实现侧向冶金结合。4)在后续中间退火过程中,共晶层与两侧的铜、银基体相互扩散,铜、银原子向更深的方向逐渐扩散,在靠近共晶层铜侧和银侧逐步形成固溶体层,使银与铜的结合强度进一步提高。银铜侧向复合界面结合机理包含机械咬合结合、接触共晶反应自钎焊结合和原子扩散结合3种,复合界面结合强度较好,剪切强度达220 MPa。

导电复合材料涂覆式全织物基柔性压阻传感器制备

针对目前织物基柔性压阻传感器制备工艺相对复杂、导电材料与织物结合度有限等问题,提出以聚二甲基硅氧烷(PDMS)-多壁碳纳米管(MWCNTs)/炭黑(CB)为导电复合材料涂覆非织造布制备压敏层,采用微滴喷射技术在织物表面直接成形叉指型金属电极,制备织物基柔性压阻传感器的方法。当CB与MWCNTs质量比为3∶2时,对不同MWCNTs填充量下导电复合材料形态及制备的压敏层微观形貌观察,并研究其对传感器灵敏度的影响,最后对制得传感器的性能及应用进行测试。结果表明:导电材料在PDMS中分散均匀,导电复合材料与织物结合紧密;当MWCNTs质量分数为2.5%时,所制传感器灵敏度最高可达0.353 kPa^(-1),检测范围为0~25 kPa,响应/恢复时间为150/200 ms,最低检测限约为49 Pa,具有良好的重复稳定性(约1 600次)。此外,该传感器可识别出手指按压以及手指和腕部弯曲的压力信号,可应用于人体健康、运动等信号监测。

基于ENEPIG镀层的无压纳米银膏烧结失效分析

总结了在化学镍钯浸金(ENEPIG)镀层上采用纳米银膏进行无压烧结时出现的失效模式。通过分析烧结镀层的微观形貌及力学性能,确认界面污染、烧结不充分及镀层缺陷是导致烧结失效的主要原因。应特别关注镍原子向镀层表面扩散导致的烧结失效风险。为保证烧结质量的稳定性和可靠性,需要充分重视界面的洁净度,对芯片、基板的存储条件和存储寿命实施严格管控,还需要优化烧结曲线,充分考虑溶剂释出所需时间、烧结峰值温度及其停留时间、降温速率等因素。研究结果为纳米银膏的无压烧结研究提供了新的理论参考。

热处理对银包铜粉表面光滑度的影响

为解决银包铜粉在导电浆料中的应用问题,本文采用化学镀与浸涂法结合制备银包铜粉,通过控制热处理工艺来改善镀银层表面的平整光滑性,并利用扫描电镜、电阻测试仪等研究了热处理工艺对银包铜粉镀银层形貌、抗氧化性、导电性和吸油率的影响。研究发现:采用化学镀与浸涂法结合的方法,可以制备表面更光滑的银包铜粉;随着热处理温度的升高,银层愈加光滑平整;但当热处理温度为700℃时,银包铜粉会出现破裂团聚的现象,且随着热处理时间的延长,银包铜粉结构发生畸变和团聚。研究表明,控制热处理工艺可以改善银层表面平整光滑性,从而降低其在电子浆料中的吸油率,提高抗氧化性和导电性。当热处理温度为600℃,保温时间10 min时,制备得到的银包铜粉形貌最好,综合性能最佳。

Ti/TiN-Ag复合涂层微观结构及抗菌性能研究

为改善Ti/TiN涂层的抗菌性能,该文利用磁控溅射技术制备不同Ag含量的Ti/TiN-Ag复合涂层(0 at.%、0.46 at.%、6.45 at.%、15.57 at.%)。利用EDS和XRD分析涂层化学成和相结构;采用AFM检测涂层平均表面粗糙度;参照GB/T 31402—2015/ISO22196表面抗菌性能试验方法评估不同Ag含量的Ti/TiN-Ag复合涂层抗菌性能。研究结果表明,当Ag含量增大到6.45 at.%或更高时,可以明显观察到Ti/TiN-Ag涂层表面存在大量Ag颗粒。Ti/TiN-Ag涂层的抗菌率随Ag含量的上升先上升、后下降。当Ag含量为0 at.%时,其抗菌率仅为29.92%;当Ag含量为6.45 at.%时,涂层抗菌率达到峰值79.37%。

刺绣心电电极设计与性能分析

为提高刺绣心电电极的灵敏性和稳定性,规范电极设计与应用,分别对刺绣电极的面积、图案、针迹进行设计,并分析其影响要素。采用控制变量的实验方案,分析电极厚度、平整度、皮肤-电极界面阻抗、信噪比、基线稳定时间、基线偏移幅度的变化规律,找出刺绣电极物理特征和电学性能的影响因素。研究结果发现:刺绣电极面积过大或过小都会对其传感灵敏性和捕捉的信号质量造成负面影响;刺绣电极图案越接近圆形其各项性能均越好;成品厚度均匀、表面平整的针迹制备的刺绣电极传感稳定性和信号质量更好;经过优化设计得出的5.3 cm^(2)圆形缎纹针迹刺绣电极,与3M公司生产的2223CN医用电极相比,皮肤-电极界面阻抗降低了1.064 MΩ,信噪比提高了3.133 dB,基线稳定时间缩短了3 s,基线偏移幅度减小0.07 mV,具有良好的外观平整度、电学灵敏性及稳定性。

丁二酰亚胺对低共熔溶剂中银成核机理的影响

本文采用循环伏安法(CV)和计时电流法(CA)考察了在有无丁二酰亚胺添加的条件下低共熔溶剂(DESs)中银的结晶成核机理;利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)观察镀液浓度变化对镀层微观形貌以及相组成的影响。计时电流的结果表明,丁二酰亚胺的加入使Ag的结晶方式发生改变,Ag在DESs-0.6 mol/L丁二酰亚胺和0.1 mol/LAgNO_(3)中电结晶过程是受扩散控制的三维连续成核。随着丁二酰亚胺的加入,镀层表面Ag结晶更加细致,结晶度增大,并且银镀层耐腐蚀性能得到提高。

硝酸银溶液协同改性中心静脉导管覆涂材料的应用性能测试

针对传统中心静脉导管材料抗菌性能和生物相容性较差的问题,提出一种新型医用载银中心静脉导管改性,并对其综合性能进行研究。结果表明,在聚多巴胺中心静脉导管表面的纳米银颗粒成功负载。硝酸银浓度为0.01 mol/L制备的载银中心静脉导管材料(0.01 Ag-DH/CVC)在较低载银含量的条件下表现出良好的抑菌性能和生物相容性,不会对细胞活性和细胞的形态产生影响。制备的载银中心静脉导管用于临床护理应用,在穿刺成功率和并发症发生率方面均明显优于传统PICC导管,表现出良好的医用性能。

氧化石墨烯强化银镀层的耐蚀性和耐磨性研究

为满足电连接器在服役过程中对导电银镀层的耐蚀性和耐磨性的需求,本文基于5,5-二甲基乙内酰脲作为主络合剂的无氰镀银溶液,通过添加氧化石墨烯纳米片,采用直流电沉积在铜基材表面制备了银-氧化石墨烯复合镀层。采用光学显微镜、扫描电子显微镜、能谱仪、X射线衍射仪对镀层表面形貌、成分和晶体结构进行了表征,并通过电化学实验和摩擦磨损试验对复合镀层的耐蚀性和耐磨性进行了测试。结果表明,氧化石墨烯的掺入改变了银的晶体生长方向,并细化了组织,提高了银镀层的硬度、耐蚀性与耐磨性。

镀银铜基电接触器件在沿海大气环境中的组织结构变化

[目的]研究镀银铜基电接触器件暴露在沿海大气环境中时镀银层的组织变化过程。[方法]分析和比较了镀银铜基电接触器件在海洋大气中暴露不同时间后的宏观形貌、微观形貌及其腐蚀电化学行为。[结果]在海洋大气中暴露1年时电接触器件为银白色,3年后变为浅黄色,6年后电接触器件表面布满铜绿。微观形貌观察表明,电接触器件在海洋大气中暴露的前3年内镀银层基本完好,其主要物相为单质Ag和Ag2O。6年后镀银层基本脱落,主要物相为Cu、CuO和Cu(OH)2。电化学测试表明,电接触器件的导电性随着海洋大气暴露时间的延长而逐渐变差。[结论]本研究可为镀银铜基电接触器件在沿海大气环境中使用寿命的评估提供参考。

光学检测传感器窗口自清洁耐刮擦涂层的制备及性能研究

针对光学法化学需氧量(COD)监测传感器窗口长期在污水中工作,易附着污物、微生物,导致玻璃透光性下降进而寿命缩短的问题,设计制备了一种光学检测窗口用透明自清洁耐刮擦涂层,使细菌、藻类等生物无法黏附在玻璃表面,以保证检测效果。以两种含氟高分子乳液[聚四氟乙烯和六氟丙烯共聚物(F46)、四氟乙烯和全氟烷氧基乙烯基醚共聚物(PFA)]为前体,通过加入适量环氧树脂提升涂层性能。系统研究了复合体系的固含率和环氧树脂的添加量对涂层性能的影响。结果发现,当环氧树脂与含氟高分子固体质量比为1∶19时,制备得到的PFA基复合涂层透明,具有自清洁功能(疏水角可达127.8°),且耐刮擦性能优异。进一步向PFA基复合涂层中添加纳米银颗粒后,涂层的抑菌率达到41.9%。