Effect of micron sized silver particles concentration on the adhesion induced by sintering and antibacterial properties of hydroxyapatite microcomposites

In this paper, silver microparticles were proposed as an additive (wetting agent) in the sintering of bovine bone-derived hydroxyapatite, and their well-known antibacterial properties were evaluated for the newly-developed materials. Hydroxyapatite was prepared by thermal processing of bovine bones, followed by milling and sorting. After silver addition, the samples were tested as precursors, green compacts and adhered particles-sintered compacts, using complementary morphological, compositional and structural evaluation techniques (scanning electron microscopy coupled with energy dispersive spectrometry, Fourier infrared spectroscopy, X-ray diffraction). The antibacterial effect was assessed on bacterial strains popular for their association with post-implantation infections. The study was designed to evaluate the precursors, investigate the surface, morphology and/or structure changes during forming and adhesion by sintering, and explore the relationship between the silver concentration and the antibacterial effect of the material. The results confirmed the benefits of adding silver as a wetting agent in sintering bovine bone-derived hydroxyapatite as well as its antibacterial effect (with best results at 2 wt%Ag). In spite of the great potential as a wetting agent and antibacterial factor in hydroxyapatite, the proper evaluation of these results requires extensive testing for elevating the control level in designing the material properties, and for establishing optimal concentrations of silver in order to achieve proper antibacterial and biocompatible behaviours.     

柔性纳米银线导电薄膜的制备及其性能研究

通过2步加入多元醇热还原法制备出了高长径比的纳米银线,并在柔性基材上制备兼具透光性和导电性的薄膜;对薄膜与基材的粘接性能进行了改善。采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、场发射透射电子显微镜(FETEM)对纳米银线的相结构及形貌进行了分析及表征。薄膜的透光率和导电性分别通过紫外-可见分光光度计和四探针进行了研究。制备的纳米银线的直径约为50 nm,长径比为200~300。研究了银线浓度以及用量对真空抽滤转移法制备薄膜的透光率及导电性的影响,发现当银纳米线的浓度为0.025mg/mL,薄膜的透光率为71.0%时,方块电阻为65.5Ω/sq。所制备的薄膜在基材上的粘接性通过旋涂一层聚偏氟乙烯(PVDF),并经热处理后,粘接性和导电性(方阻为18.0Ω/sq)都有所提高。     

Electroless silver deposition on Si(100) substrate based on the seed layer of silver itself

A new method for silver electroless deposition on Si(100) wafer, based on the silver itself as the seed layer, was developed. The seed layer was first deposited onto the etched wafer surface in an acidic solution of 0.005 mol l⁻¹ AgNO₃+0.06 mol l⁻¹ HF. Then the silver thin film was electrolessly deposited upon the seed layer in the electroless bath of AgNO₃+NH₃+acetic acid+NH₂NH₂ (pH 10.2). The NH₂NH₂ was taken as the reducing agent. The morphology of the seed layer and the silver film were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDX). The experimental results indicated that the seed layer showed excellent catalytic function for silver electroless deposition.     

Effect of dislocation density on adhesion strength of electroforming Ni layer on Cu substrate

Adhesion plays a critical role in the reliability of the micro devices in MEMS. However, the quality of the micro devices fabricated by electroforming technology is influenced by the poor adhesion performance. In order to improve the poor adhesion performance, from the view of the dislocation density, this paper investigates the effect of the current density on the adhesion originally. To research the effect of the dislocation density, electroforming experiments were processed under two different current densities. The dislocation density and the compressive stress of the electroforming layer was measured by XRD method. The dislocation was observed by TEM method. The adhesion strength was tested by scratch test. The experimental results show that the small current density reduces the dislocation density and the compressive stress, increases the adhesion. The mechanisms are that the small current density reduces the dislocation density. The low dislocation density can reduce the compressive stress and increase the adhesion. This work can improve the adhesion of the electroforming layer.     

不同还原体系银油墨打印对聚酰亚胺基板化学镀铜制备印制电路板的影响

先在普通打印机上用活化导电银油墨将线路图打印在聚酰亚胺(PI)基板上,固化后再化学镀铜制得印制电路板(PCB)。研究了导电银油墨的还原剂对不同体系镀液化学镀铜层厚度、导电性、结合力和抗氧化性的影响。结果表明,油墨的还原剂相同时,甲醛体系化学镀铜层的综合性能优于乙醛酸镀液。导电银油墨的最佳还原剂为丙酸,即油墨的最佳配方为:丙酸0.5 mol/L,Ag NO3 0.5 mol/L,10%(质量分数)OP乳化剂适量。采用0.5 mol/L丙酸油墨–甲醛镀液体系制得厚度为3.10μm的铜镀层,其抗氧化时间为44 s,电阻率为1.00×10-7?·m,与PI基板间的结合力良好,综合性能最佳。     

电流密度对5,5-二甲基乙内酰脲体系电镀银的影响

采用5,5-二甲基乙内酰脲体系在黄铜及不锈钢基体上沉积厚度为6μm左右的银镀层,镀液组成和工艺条件为:硝酸银25 g/L,5,5-二甲基乙内酰脲80 g/L,烟酰胺60 g/L,碳酸钾40 g/L,复合光亮剂(包含2-巯基苯骈噻唑、1,4-丁炔二醇和十二烷基硫酸钠)2 mL/L,pH 10.5,温度60°C,电流密度0...     

Microstructure,adhesion, and tribological properties of conventional plasma-sprayed coatings on steel substrate

A variety of metallic and oxide coatings were deposited under various conditions on 1020 mild steel substrate by conventional plasma spraying. The coating thickness, microhardness, cohesion and adhesion failure loads, friction coefficient, and abrasive wear resistance were evaluated. The coatings were classified as follows, in order of decreasing microhardness and wear resistance: alumina, chromia, 316 stainless steel, Ni-5% Al, elemental aluminum and aluminum-polyester. Wear resistance increased with increasing microhardness and decreasing friction coefficient. The microhardness and wear resistance of high-velocity oxy-fuel (HVOF) diamond jet (DJ)-sprayed aluminum were found to be superior to those of plasma-sprayed aluminum. Plasma or flame-sprayed metallic coatings adhered well to the substrate. The cohesion, adhesion, microhardness, and wear resistance of alumina coatings exceeded those of equally thick chromia coatings.     

Sintering behavior and effect of silver nanoparticles on the resistivity of electrically conductive adhesives composed of silver flakes

In this paper, silver nanoparticles with size of 30–50 nm were synthesized by reducing silver nitrate with sodium borohydride and sodium citrate and using PVP as an adsorption agent in the ethanol solution. The experimental results indicate that the morphologies and sintering behaviors of both kinds of silver nanoparticles are impacted by glutaric acid and sintering temperature. The electrically conductive adhesives (ECAs) filled with micro-sized silver flakes and silver nanoparticles as hybrid fillers were fabricated and the electrical properties were investigated based on the fraction of the silver nanoparticles of the total of silver flakes and the curing temperature, etc. The incorporation of the untreated/treated silver nanoparticles into the polymer matrix with 65?wt% silver filler the resistivity increased in almost all cases, especially the high fraction and the low curing temperature. The curing temperature has influence on the resistivity of the ECAs filled with micro-sized silver flakes and the silver nanoparticles due to the sintering of the silver nanoparticles. The addition of 10% treated silver nanoparticles into the ECAs with 60?wt% silver fillers, the resistivity is slightly lower than that of the ECAs with micro-sized silver flakes. In the system of the ECAs with the high loading of silver fillers, the untreated/treated silver nanoparticles have little effect on the electrical conductivity. The results suggest that the morphology and distribution of silver fillers are the key to affect the conductivity of ECAs when nanoparticles are included in the system.     

活塞丝网印刷石墨涂层质量问题分析

介绍了丝网印刷技术以及运用D10涂料进行活塞丝网印刷技术的工作原理以及活塞丝网印刷石墨涂层的工艺流程。对生产中存在的涂层结合强度差以及造成涂层外观质量问题的各种现象如鼓泡、针孔、漏印和固体异物等的成因进行了分析。指出了固化温度和时间控制是影响涂层结合强度的主要因素。     

Effect of paper and printing press variables on the rates of adhesion failure in the linting of offset printing

Lint problems occur when loosely bonded particles detach from the surface of uncoated paper and accumulate on the printing blanket. We investigated the effect of paper and the printing press variables of printing tone and ink tack on linting using a lint camera system and also by stopping the press repeatedly to wash the lint samples off the blanket. Lint particles were classified into small particles (with area 0–8000?μm²) and large particles (with area above 8000?μm²). There have been many contradictory reports about the most important paper and printing variables affecting linting because many previous researchers have not adequately addressed that linting is a dynamic process, which involves two adhesion failures and separations, driven by the splitting of the viscous ink film. The first failure is for the removal of lint particles from the paper surface to the blanket, while the second failure is for the separation of the lint particles from the blanket. The key finding of this study is that these two rates of adhesion failure are generally correlated. That is, a higher rate of lint particle separation from the paper surface is associated with a higher rate of separation from the blanket. This finding held for varying the grade of paper, the ink viscosity and the printing tone, and for small and large particles. Previous contradictory results from linting studies are because lint has only been measured after completing a printing trial, with no means of examining the two underlying adhesion failure processes.     

PVC压延膜印刷粘着现象的原因及改进

分析了PVC压延膜印刷后粘着现象产生的原因及改进方法.     

Effect of titania addition on adhesion of silver colloids to glass substrate

The purpose of this study was to investigate the effects of titania addition on adhesion strength of silver colloids to glass substrate. Our results indicated that when the pH was adjusted to 10, the mixed slurry of titania and silver colloids was stable with no sign of settling at approximately 4 hr. After film deposition by doctor blade method and subsequent sintering treatment, the adhesion strength between silver film and glass substrate was measured by both ASTM D3359 and D4541 standards. The results showed positive correlation of adhesion strength to both the titania concentration and sintering temperature. The adhesion strength reached 7.0 MPa when we added 8 wt% titania (based on silver) and sintered the film at 320°C for 20 min. X-ray photoelectron spectroscopy data revealed that interdiffusion of Ti into both glass substrate and silver colloid might be responsible for adhesion enhancement. On the other hand, the electrical resistivity of films increased with titania addition. This fact implied that we need to compromise between these two properties when titania addition was used to improve adhesion between silver colloid and glass substrate. An empirical model was subsequently proposed to simulate the compromise between adhesion strength and electrical resistivity.     

钛合金镀铜、镀银工艺

为克服钛合金氰化镀铜、镀银层结合力不良的问题,通过改变基体预处理方式设计了5个镀铜、镀银方案并进行结合力表征,得到钛合金镀铜、镀银的最佳工艺流程为:湿吹砂─保护─轻石灰刷洗除油─冷水洗─酸性镀铜或氰化镀银─冷水洗─压缩空气吹干。生产实践证明采用该工艺电镀所得产品结合力均合格,且含氢量不超标。介绍了电镀过程中控制钛合金含氢量的方法和注意事项。     

烟酸脉冲镀银及镀层性能的实验室研究

研究了烟酸体系双脉冲镀银的工艺条件对镀层的沉积速率.外观质量、结合力、抗变色能力及表面形貌的影响.在最佳工艺条件下,与丁二酰亚胺镀银工艺进行了比较.结果表明,电流密度为0.25A/dm2、频率为1 000Hz、温度为25℃时,可获得光亮、抗变色能力好的镀层.与丁二酰亚胺体系得到的镀层相比较,烟酸体系镀层性能更优.镀层银晶为立方晶系.     

Swelling and adhesion characteristics of lignin-filled polyurethane sealant

Previously, polyurethane (PU)-lignin polyblend sealants from the point of view of adhesion to various substrates, morphology based on scanning electron microscopy, and miscibility based on differential scanning calorimetry (DSC) and ¹³C nuclear magnetic resonance (NMR) were studied. In this study the same polyblends together with PU filled with a few mineral fillers were used. Swelling tests were applied to establish the number average molecular weight between crosslinks of the PU and to assess the degree of interaction between various fillers including different types of lignin and the PU matrix. Lignins were found to restrict less the degree of swelling of PU than that by the Sillitin (siliceous clay)-Titanox TiO₂ 3.17: 1 wt/wt mixture. Data based on the swelling method show that lignins do not interact with the elastomer matrix to as great an extent as Sillitin/Titanox filler mixture, a finding which is in good agreement with the former DSC and NMR results.     

纳米颗粒对环氧树脂胶粘剂／钢铁附着强度的影响

采用纳米Al2O3、纳米CaCO3、纳米SiO2三种纳米颗粒,机械混合对环氧树脂胶粘剂进行改性,并对纳米颗粒改性的环氧树脂胶粘试样进行了附着强度的检测。结果发现,通过改变纳米颗粒的种类和含量,环氧胶粘剂／钢铁基体之间的附着强度得到不同程度的提高,其中添加2％纳米Al2O3颗粒的环氧胶粘剂与钢铁基体的附着强度提高了4倍左右。通过断面形貌特征和不同基体粗糙度下对添加纳米颗粒环氧胶与钢铁基体之间附着强度的检测,对此现象产生的原因进行了分析和讨论。     

The effect of substrate preparation on the adhesion of polyethylene to aluminium

Polyethylene coatings were applied to aluminium by melting, and adhesion measured by a peel test. The formation of hydrated oxide films on the metal is shown to greatly increase adhesion for coatings applied in nitrogen, through formation of needle-shaped oxide crystals. Particles of oxide deposited on the metal are found to have a similar effect. These treatments improve the durability of the bond when exposed to water, especially when coatings have been applied in air.     

银包铝粉工艺研究

对8种银包铝粉实验方案进行了研究。确定了最佳方案:碱洗—稀盐酸活化—酸性镀铜—置换法镀银。探讨了银包铝粉的电阻与酸铜溶液中硫酸铜的质量浓度、铝粉中银的质量分数的关系。确定了硫酸铜的最佳质量浓度为50g/L,铝粉中银的最佳质量分数为25%。获得了银白色的银包铝粉,其松装密度为0.56g/mL,平均电阻值为10mΩ。     

湿法钴盐粘合增进剂的合成及其特性

简要介绍湿法钴盐粘合增进剂的合成方法,分析湿法合成工艺的特点并比较湿法与干法工艺的差别.对采用两种钴盐粘合增进剂的镀黄铜钢丝粘合胶进行了小配合和大配合试验,结果表明湿法产品的耐老化性能优于干法产品.     

Influence of surface characteristics on the adhesion of Alcaligenes denitrificans to polymeric substrates

The adhesion of Alcaligenes denitrificans to several polymeric materials was investigated. As the nature of the surfaces of the micro-organisms and the substrate materials is an important factor in the adhesion process, characteristics such as the electrokinetic potential and hydrophobicity were also determined and correlated with the capacity of bacterial cells to adhere to solid surfaces. The substrates used were high-density polyethylene (HDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and poly(methyl methacrylate) (PMMA). The electrokinetic potential of the cells and the substrates was determined by measurements of electrophoretic mobility and the hydrophobicity was determined by contact angle measurements. All the substrates studied as well as the bacterial strain have a negative zeta potential, which means that adhesion is not mediated by electrostatic interactions. As far as hydrophobicity is concerned, PP is the most hydrophobic material, PMMA is the least hydrophobic, whereas HDPE and PVC present an intermediate behavior. As bacteria cells are hydrophilic, adhesion is favored to PP; therefore, this substrate material seems to be the one that promotes a stronger adhesion and the development of the most stable biofilm for use as a biomass carrier in denitrifying inverse fluidized bed reactors. This was confirmed by the results of adhesion tests. In this way, adhesion seems to be dominated by hydrophobic interactions.