Microstructures and bond strengths of the calcium phosphate coatings formed on titanium from different simulated body fluids

Calcium phosphate (Ca-P) coatings were deposited on Ti substrates by a biomimetic method from m-SBF and 10× SBF, respectively. Comparative study of microstructures and bond strengths of the Ca-P coatings deposited from those different SBFs was carried out. Effect of the surface roughness of the substrates on the bond strength of the Ca-P coatings was also studied. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transformed infrared spectroscopy (FTIR), inductive coupled plasma spectrometry (ICP) and thermogravimetry (TG) were used to characterize the Ca-P coatings. The bond strengths between the coatings and Ti substrates were measured using an adhesive strength test. Results indicated that the ionic concentrations of the SBFs and the surface roughness of the substrate had a significant influence on the formation, morphology and bond strength of the Ca-P precipitates. The induction period of time to deposit a complete Ca-P layer from the m-SBF is much longer, but the Ca-P coating is denser and has higher bond strength than that formed from the 10× SBF. The Ti with a surface roughness of R_a 0.64 µm and R_z 2.81 µm favoures the formation of a compact Ca-P coating from the m-SBF with the highest bond strength of approximately 15.5 MPa.     

Effect of grain size on grain boundary strengthening of copper bicrystals under cyclic loading

Abstract

To clarify the strengthening effect of grain boundaries (GB), cyclic deformation behaviour of really grown [4¯79] ∥ [1¯25] copper bicrystals with different widths (4, 6, and 8 mm, denoted RB-4, RB-6, and RB-8) of com-ponent crystals and a combined copper bicrystal (denoted CB-6), obtained by sticking component single crystals G1 [4¯79] and G2 [1¯25] together, was investigated. The results showed that the cyclic saturation stresses increased in the order of bicrystals of CB-6 < RB-8 < RB-6 < RB-4. It is indicated that the GB effect caused different degrees of strengthening, which increased with the decreasing width of the RB bicrystals. By surface observation, it was found that only the primary slip system was activated in the combined bicrystal during cyclic deformation. However, an additional slip system appeared near the GB within the crystal G2 [1¯25] in the RB bicrystals (except in the primary slip system), and formed a GB affected zone (GBAZ). The width of the GBAZ was about 400 and 600 μm at plastic strain amplitudes of 0·1% and 0·2% respectively. Meanwhile, using an electron channelling contrast (ECC) technique in the SEM, the dislocation patterns near the GB and within the component crystals were observed. It was found that a two phase structure of persistent slip bands (PSBs) and matrix (or veins) can form in these bicrystals, similar to that in copper single crystals. But these PSBs cannot transfer through the GB during cyclic deformation. Based on the results above, the effect of grain size on GB strengthening of copper bicrystals was discussed.     

Semi-conductive properties of passive films formed on copper in chromate solutions

The semi-conductive properties of passive films formed on copper in chromate solutions were investigated by means of capacitance measurements. The effects of the formation potential and temperature, chloride and chromate concentration in electrolyte solution, as well as measured frequency on the semi-conductive properties of passive films were studied. The results show that the passive films formed on copper display n-type semi-conductive characteristics. The slopes of the straight lines in Mott-Schottky plots decrease with moving the formation potential toward positive, increasing the chloride ion concentration, decreasing the formation temperature and the chromate solutions concentration. Moreover, the initial grain size of copper surface impacts remarkably on the semi-conductive properties. The donor density of the passive films formed on ultra-fine grained (UFG) copper is higher than that of the passive films on coarse-grained (CG) copper.     

基体对镁合金氧化膜性能影响的研究进展

阐述了镁合金应用前景,介绍了阳极氧化特点以及影响氧化膜性能的因素,主要包括基体材料、电参数、电解液的组成及其浓度等.全面综述了基体对镁合金氧化膜成膜过程、成分、表面形貌以及耐蚀性的影响,提出了由于工业上使用的材料绝大多数为镁合金而不是纯镁,因此,开展合金元素对氧化膜性能影响的研究非常必要.     

铜基高梯度润湿表面的构建与表征

通过向垂直放有铜片的烧杯中滴加Ag NO3溶液,在铜片上制备出水接触角从平整铜表面的90.8°升至151.4°的梯度润湿表面;结合前期以碱辅助氧化法制备亲水区间的梯度润湿表面,实现了在无低表面能物质修饰时,构建从超疏水(151.6°)至超亲水(3.7°)的高梯度润湿铜表面。制得的润湿性梯度在近100℃的水浴中浸泡10 h,各点的接触角变化最大不超过10°。采用扫描电镜(SEM)和X射线衍射(XRD)等对样品表面形貌演变和结构进行分析,表明在铜表面分别沉积具有相对疏水的银粒子和亲水特性的氢氧化铜粒子,并形成合理的粗糙结构,可使铜片分别达到超疏水和超亲水状态,从而形成高梯度润湿铜表面。由于平整的银表面和氢氧化铜表面的水接触角分别为72.8和62°,这也从另一侧面说明亲水与疏水的界限在65°可能更加合理。     

Protrusion and whisker growth on tin coated copper substrate under stresses

Abstract

Tin thin films were coated on copper substrates using chemical method. Tin coated copper specimens under continuously applied compressive and tensile stresses were oxidised at 100°C for 8 days. Protrusion and whisker growth behaviour of tin coated copper specimens was characterised by scanning electron microscope, X-ray diffractometer and transmission electron microscope. The results show that continuously applied compressive stress on tin coated copper specimens would enhance the growth of whisker while tensile stress would reduce whisker growth. A SnO₂ layer was formed during oxidation and intermetallics of Cu₃Sn and Cu₆Sn₅ were formed between SnO₂ layer and copper substrate, which built up the residual compressive stresses in the coated tin layer. Continuously applied stress on the specimens can change the magnitude of residual compressive stress in coated tin layer, which affects the driving force for protrusion and whisker formation and growth.     

Electrodeposition and morphology analysis of Bi-Te thermoelectric alloy nanoparticles on copper substrate

Nanoscale Bi-Te particles with thermoelectric properties on copper substrate were investigated. The substrate was prepared by electroplating copper layer on a copper zinc alloy plate in a copper sulfate solution. Electrodeposition of the Bi-Te alloy particles was then performed in a nitrate bath. The electrolyte is composed of 0.05 M bismuth nitrate and 0.01 M tellurium dioxide dissolved in 2.0 M HNO₃. Cyclic voltammetry and quartz microbalance tests associated with the electrodeposition process were conducted to show the mechanism and kinetics of the deposition. The morphology and compositional analysis of Bi-Te was obtained using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) respectively. The morphology analysis suggested that nanoscale Bi-Te particles were obtained and the EDS results indicated that the surface of the copper substrate contained Cu₂O. The atomic ratio 1:1 for Bi:Te in the alloy, which is equivalent to the weight percentage of Bi:Te = 62%:38% was confirmed from the data obtained.     

基板预热温度对激光金属沉积成形零件微观组织的影响

基板预热可以显著降低激光金属沉积成形（laser metal deposition shaping, LMDS）过程的热应力,从而抑制成形过程裂缝的产生,但基板预热温度的高低对成形零件的微观组织有着重要的影响,因此研究不同基板预热温度下激光金属沉积成形零件的微观组织变化规律对基板预热温度的选择具有非常重要的意义.利用中国科学院沈阳自动化研究所自行研制的激光金属沉积成形系统和基板预热系统,采用Ni60A金属粉末在基板未预热和预热到200,300,400,500和600 ℃时分别进行成形试验.然后利用扫描电子显微镜和能量散射谱仪对成形试件的微观组织进行深入的研究,得到不同基板预热温度对激光金属沉积成形零件微观组织的影响规律,为基板预热温度的优化选择提供了重要参考.     

柔性ITO衬底上铜酞菁薄膜有序生长的X射线衍射研究

采用石英晶体微天平实时监测薄膜生长速率,通过控制衬底温度与薄膜生长速率,在柔性ITO导电衬底上真空蒸发沉积了铜酞菁薄膜.X射线衍射分析表明,适当提高衬底温度与薄膜生长速率,可促进薄膜的有序生长.当衬底温度为90℃,生长速率为10nm/min时,薄膜的有序度最高,薄膜晶型呈(相和(200)晶面.     

Al和Li对镁基体氧化膜成分及厚度影响

合金元素对氧化膜性能影响很大。分别恒流氧化了纯镁、AZ91HP和Mg-Li合金并测量了氧化膜成分及厚度。EDX分析表明，在Mg—Li合金上形成的氧化膜P含量最高（39．39％），AZ91HP上最低（35．88％）；膜厚测量结果为Al和Li分别使氧化膜厚度稍微减少和大大增加。Al和Li元素对氧化膜性能影响可以用Mg^2＋、Al^3＋和Li^＋移动速度不同以及MgO、Al2O3和Li2O的PBR（Pilling—Bedweorth ratio）值不同来解释。     

Evolution of microstructure and electrical conductivity of electroless copper deposits on a glass substrate

This paper describes the evolution of the microstructure and conductivity of electroless copper deposition on a glass substrate for applications in electronics manufacture. The glass was activated using a (3-aminopropyl)trimethoxysilane pre-treatment followed by a Pd/Sn catalyst. Surface morphology of the deposited copper films was characterized using a dual beam focused ion beam field emission scanning electron microscope, and together with atomic force microscopy, showed clearly that the roughness and grain size tended to increase with the plating time. Film thickness measurements showed a high initial deposition rate, which slowed to a constant level as the thickness increased above 100 nm. This corresponded with the resistivity of the films which decreased rapidly as the thickness increased from 20 to 100 nm, but then remained largely stable at a level approximately twice that of bulk copper.     

Fabrication of hollow-sphere films of wurtzite CuInS2 on copper substrate

As important semiconductors, I–III–VI₂ compounds have attracted wide attention, among which the wurtzite structured CuInS₂ has been the research focus due to its metastable phase. In this paper, the wurtzite CuInS₂ hollow-sphere films have been successfully prepared on copper substrate in a self-designed solvothermal detached system. The films of Cu(OH)₂ one-dimensional nanostructure arrays and thioacetamide were used as the precursors and triethylene glycol was used as the solvent. Experiments showed that the amount of indium trichloride played a determinative role in the final morphology of the products. Meanwhile, the one-dimensional nanostructure arrays and the detached solvothermal system have great influences on the crystal shape as well. Based on the experimental results, a possible formation mechanism for the CuInS₂ hollow spheres was also proposed. The UV–Vis absorption spectrum showed a broad absorption over the entire visible light and extending into the near-infrared region and presented the band gap of 1.53 eV for the as-prepared wurtzite CuInS₂, which indicates the potential applications in solar cells.     

Galvanic deposition of nanocrystalline ZnO thin films from a ZnO-Zn(OH)(2) mixed phase precursor on p-Si substrate

A galvanic technique for the deposition of ZnO thin films is reported. The depositions were carried out on p-type single-crystal silicon substrates at room temperature, from a solution of ZnSO(4), where the Zn rod acted as a sacrificing anode and p-Si was the cathode. The deposition of ZnO by this method is pH sensitive, and a pH between 4 and 5 is found to be optimum for film deposition. This deposition technique is simple, inexpensive and can be carried out at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies revealed the nanocrystalline structure of the films. The resistivity of the annealed ZnO films was determined by the Van der Pauw measurement technique.     

Effect of tungsten addition on thermal conductivity of graphite/copper composites

Graphite/copper composites with high thermal conductivity were fabricated by tungsten addition, which formed a thin tungsten carbide layer at the interface. The microstructure and thermal conductivity of the composite material were studied. The results indicated that the insertion of tungsten carbide layer obviously suppressed spheroidization of copper coating on the graphite particles during the sintering process, and decreased the interfacial thermal resistance of the composites. Compared with the graphite/copper composites without tungsten, the thermal conductivity of the obtained composites was increased by 43.6%.     

Effects of specimen and grain sizes on compression strength of annealed wrought copper alloy at room temperature

Variations in compression yield strength of annealed wrought CuAl7 copper alloy with specimen diameter (t) in 1–10 mm range and grain size (D) in 24–172 μm range were investigated. Both grain size effect and feature size effect could be observed. The compression yield strength increased with a reduction in grain size or specimen diameter, and varied with the t/D ratio in no particular manner. However, when t was held constant, the compression yield strength increased as the ratio increased. When D was held constant, the strength decreased as the ratio increased. The Hall–Petch relationship between the compression yield strength and the grain size was found to depend on the specimen diameter. The effect of feature size was greater than that of grain size. A new model of the relationship between the compression yield strength and the grain size, specimen diameter, and size factor has been built. The predicted results of the model agreed well with the experimental results. The fit of the model was better than that of a model based on the relationship between the compression yield strength and the grain size and specimen diameter only.     

Effects of Y2O3 on the property of copper based contact materials

The copper based electric contact materials with multicomponent substance were obtained by powder metallurgy. The hardness and density of the samples increase with adding proper amount of Y₂O₃. Adding 1.5 wt.% Y₂O₃ the hardness of the sample reaches the maxim and the density of sample reaches the maximum by adding 2 wt.% Y₂O₃. In this paper, the effects of addition of Y₂O₃ on the performance of copper based contact materials were studied by metallographic microscope, XRD, SEM in details. Moreover, the mechanism of the effects was discussed.     

Influence of indigenous and added iron on copper extraction from soil

Experimental tests of copper leaching from a low permeability soil are presented and discussed. The objective of the experiments was to investigate the influence of indigenous and added iron in the soil towards copper mobilization. Metals’ leaching was performed by flushing (column tests) or washing (batch tests) the soil with an aqueous solution of ethylenediaminetetraacetic acid, EDTA. An excess of EDTA was used in flushing tests (up to a EDTA:Cu molar ratio of about 26.2:1), while, in washing tests, the investigated EDTA vs. copper molar ratios were in the range between 1 (equimolar tests) and 8.Copper extraction yield in flushing tests (up to about 85%) was found to depend upon contact time between the soil and the leaching solution and the characteristics of the conditioning solution. The saturation of the soil with a NaNO₃ solution before the treatment, favoured the flushing process reducing the time of percolation, but resulted in a lower metal extraction during the following percolation of EDTA.The indigenous iron was competitive with copper to form EDTA complexes only when it was present in the organic and oxides–hydroxides fractions. Artificial iron addition to the soil resulted in an increase of both the exchangeable iron and the iron bonded to the organic fraction of the soil, thus increasing the overall amount of iron available to extraction.In both batch and continuous tests, the mechanism of copper extraction was found to involve the former dissolution of metal salts, that lead to an initial high concentration of both copper and selected competitive cations (essentially Ca²⁺), and the following EDTA exchange reaction between calcium and copper complexes. The initial metal salts dissolution was found to be pH-dependant.     

电去离子过程脱除低浓度铜离子的研究

采用一级两段的膜堆,以模拟废水为对象,考察了电去离子(EDI)过程脱除低浓度铜离子的性能,为开发一种更环保更经济的重金属废水处理技术提供理论与实验基础.研究证实,脱除铜离子的EDI存在"增强传质"和"电再生"两种模式.在"增强传质"模式操作时,淡室的树脂保持为盐型,阴膜的浓室侧表面无结垢产生.在"电再生"模式下,树脂被水解离产生的H 和OH-所再生,EDI可将铜离子从 50mg/L 左右脱除至火焰原子吸收分光光度法无法检出,同时在阴膜浓室侧表面形成黑色的CuO结垢.选择适当的膜堆形式和工艺条件能够防止结垢,获得一个连续稳定的EDI过程.     

Removal of Neutral Red from aqueous solution by adsorption on spent cottonseed hull substrate

Cottonseed hull, a low-cost widely available agricultural waste in China, after used as substrate for the white rot fungus Pleurotus ostreatus cultivation, was tested for the removal of Neutral Red (NR), a cationic dye, from aqueous solution. A batch adsorption study was carried out with varied solution pH, adsorbent dosage, reaction time and initial NR concentration. The results show that the kinetics of dye removal by the spent cottonseed hull substrate (SCHS) is prompt in the first 5 min and the adsorption equilibrium can be attained after 240 min. The biosorption kinetics and equilibrium follow typical pseudo-second-order and Langmuir adsorption models. Thermodynamic parameters of ΔG°, ΔH° and ΔS° show that the adsorption is a spontaneous and endothermic process. Fourier transform infrared (FTIR) spectroscopy was used for the characterization of possible dye-biosorbent interaction. This study provides a facile method to produce low-cost biosorbent for the purification of dye contaminated water.