电沉积Co-Ni合金镀层结构及硬度的研究

采用氨基磺酸体系电解液电沉积Co-Ni合金,研究了电解液中钴、镍金属离子浓度与合金镍层中钴含量的关系。利用扫描电子显微镜和X射线衍射分析测定了不同钴含量沉积层的微观形貌和晶体结构,同时研究了合金沉积层显微硬度和合金成份的关系及热处理的影响。实验结果表明：电解液中Co^2 /(Co^2 Ni^2 ）在0.1-0.5的范围内时,钴离子的优先共沉积的趋势最强。SEM观察结果和XRD分析测试表明,随着钴镍合金沉积层中钴含量的不断增加,低钴含量合金层粗大的颗粒状结晶逐渐转变为细致、均匀的三角形状结晶,最终又形成中等大小的颗粒状结晶。同时合金层中钴含量的逐渐增加,结构由fcc镍固溶体过渡为fcc的钴固溶体,最后转变为hcp的钴固溶体。并且在形成两个钴固溶体的钴含量范围内（20％－50％和60％－80％）,所对应的钴镍合金层的硬度值远大于低钴含量区所具有fcc镍固溶体结构的合金层硬度。     

Adhesion and hardness of ion-plated TiC and TiN coatings

The microhardness and adhesion of TiC coatings on steel and cemented carbide are studied. A comparison with TiN coatings is also made. It is found that the minimum coating thickness in which a reliable microhardness measurement can be made is described satisfactorily by existing standards; departures can be expected if the coating is strongly textured. The critical load for the removal of the coating by the scratch test depends on both the coating and the substrate and is thought to reflect their mechanical properties. It appears that marked variations in the strength and nature of adhesion on cemented carbides can occur.     

Covalent-bonded graphyne polymers with high hardness

Eight covalent-bonded graphyne polymers have been proposed using the newly developed USPEX and CALYPSO methods based on the first-principle calculations. These polymers are energetically more favorable than the corresponding graphyne under ambient pressure, and seven of them are more stable than fullerene C₆₀, indicating their existence possibilities. The mechanical and dynamic stabilities of these crystal structures have been confirmed by calculating their elastic constants and phonon dispersion curves, respectively. The newly developed variable-cell nudged elastic band (VC-NEB) simulations show that the graphyne → polymer transformation exhibits lower energy barrier than the graphite → diamond transformation. Two of the graphyne polymers have been found to be superhard, and the others are hard materials. These graphyne polymers possess tunable electronic properties from metallic to semiconductive.     

Superior hardness and Young's modulus of low temperature nanocrystalline diamond coatings

Nanocrystalline diamond (NCD) coatings with thickness of about 3 μm were grown on silicon substrates at four deposition temperatures ranging from 653 to 884 °C in CH₄/H₂/Ar microwave plasmas. The morphology, structure, chemical composition and mechanical and surface properties were studied by means of Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Raman spectroscopy, nanoindentation and Water Contact Angle (WCA) techniques. The different deposition temperatures used enabled to modulate the chemical, structural and mechanical NCD properties, in particular the grain size and the shape. The characterization measurements revealed a relatively smooth surface morphology with a variable grain size, which affected the incorporated hydrogen amount and the sp² carbon content, and, as a consequence, the mechanical properties. Specifically, the hydrogen content decreased by increasing the grain size, whereas the sp² carbon content increased. The highest values of hardness (121 ± 25 GPa) and elastic modulus (1036 ± 163 GPa) were achieved in NCD film grown at the lowest value of deposition temperature, which favored the formation of elongated nanocrystallites characterized by improved hydrophobic surface properties.     

Microstructural characterization and hardness of electrodeposited nickel coatings from a sulphamate bath

Pure nickel plates were produced from a sulphamate bath by electrodeposition. A systematic variation of the current density, in the range 0.005 to 0.25 Acm^–2, resulted in a variation of the coating microstructure and properties. Deposits plated below a current density of 0.01 Acm^–2 had a surface morphology consisting of large, deep crevices surrounding smaller substructures. A banded or laminar type microstructure was observed in cross-section. Above this current density, truncated pyramidal structures, with ridged terraces oriented perpendicular to the growth direction, were found on the surface. The planar dimensions of the pyramidal surface features were found to increase with current density, as well as the columnar grain widths observed in the cross-sectional view. To evaluate the mechanical properties of the coatings, microindentation hardness tests were performed using a Knoop indenter. A Hall–Petch type relationship for the samples deposited at and above 0.01 Acm^–2 was seen.     

Adaptive neuro-fuzzy approach for predicting hardness of deposited TiN/ZrN multilayer coatings

This paper presents an adaptive neuro-fuzzy approach based on first order function of fuzzy model for establishing the relationship between control factors and thin films properties of TiN/ZrN coatings on Si(100) wafer substrates. A statistical model was designed to explore the space of the processes by an orthogonal array scheme. Eight control factors of closed unbalance magnetron sputtering system were selected for modeling the process, such as interlayer material, argon and nitrogen flow rate, titanium and zirconium target current, rotation speed, work distance, and bias voltage. Analysis of variance (ANOVA) was carried out for determining the influence of control factors. In this study, with the application of ANOVA, the smallest effect of control factors was eliminated. The adaptive neuro-fuzzy inference system (ANFIS) was applied as a tool to model the deposited process with five significant control factors. The experimental results show that ANFIS demonstrates better accuracy than additive model for the film hardness. The root mean square error between prediction values and experimental values were archived to 0.04.     

Structure,hardness and tribological properties of nanolayered TiN/TaN multilayer coatings

TiN/TaN coatings, consisting of alternating nanoscaled TiN and TaN layers, were deposited using magnetron sputtering technology. The structure, hardness, tribological properties and wear mechanism were assessed using X-ray diffraction, microhardness, ball-on-disc testing and a 3-D surface profiler, respectively. The results showed that the TiN/TaN coatings exhibited a good modulation period and a sharp interface between TiN and TaN layers. In mutilayered TiN/TaN coatings, the TiN layers had a cubic structure, but a hexagonal structure emerged among the TaN layers besides the cubic structure as the modulation period went beyond 8.5 nm. The microhardness was affected by the modulation period and a maximum hardness value of 31.5 GPa appeared at a modulation period of 8.5 nm. The coefficient of friction was high and the wear resistance was improved for TiN/TaN coatings compared with a homogenous TiN coating, the wear mechanism exhibited predominantly ploughing, material transfer and local spallation.     

Structure, hardness and thermal stability of nanolayered TiN/CrN multilayer coatings

Nanolayered TiN/CrN multilayer coatings were deposited on silicon substrates using a reactive DC magnetron sputtering process at various modulation wavelengths (Λ), substrate biases (V_B) and substrate temperatures (T_S). X-ray diffraction (XRD), nanoindentation and atomic force microscopy (AFM) were used to characterize the coatings. The XRD confirmed the formation of superlattice structure at low modulation wavelengths. The maximum hardness of the TiN/CrN multilayers was 3800 kg/mm² at Λ=80  Å, V_B=−150 V and T_S=400°C. Thermal stability of TiN, CrN and TiN/CrN multilayer coatings was studied by heating the coatings in air in the temperature range (T_A) of 400-800°C. The XRD data revealed that TiN/CrN multilayers retained superlattice structure even up to 700°C and oxides were detected only after T_A?750°C, whereas for single layer TiN and CrN coatings oxides were detected even at 550°C and 600°C, respectively. Nanoindentation measurements showed that TiN/CrN multilayers retained a hardness of 2800 kg/mm² upon annealing at 700°C, and this decrease in the hardness was attributed to interdiffusion at the interfaces.     

The effects of nitrogen bonding on hardness of AIN/CrN multilayer hard coatings

AIN/CrN multilayer hard coatings with various bilayer thicknesses were fabricated by a reactive sputtering process. The microstructural and mechanical characterizations of multilayer coatings were investigated through transmission electron microscope (TEM) observations and the hardness measurements by nano indentation. In particular, the variation of chemical bonding states of the bilayer nitrides was elucidated by near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Many broken nitrogen bonds were formed by decreasing the bilayer thickness of AIN/CrN multilayer coatings. Existence of optimum AIN/CrN multilayer coatings thickness for maximum hardness could be explained by the competition of softening by the formation of broken nitrogen bonds and strengthening induced by decreasing bilayer thickness.     

A device for simultaneous determination of the impact resistance and hardness of insulating coatings of pipelines

We propose a hand-operated device for simultaneous determination of the impact resistance and hardness of anticorrosive insulating coatings, which completely models the work of a U-1 standard vertical impact testing machine. The proposed device is a prototype of the Poldi impact hardness gauge, however, unlike the latter, our device is used with a hammer of mass 1 kg, which equates it to the U-1 impact testing machine and enables one to determine simultaneously the hardness and impact resistance of protective coatings. When the hammer strikes, the indenter contacts simultaneously with the coating and indicator metal (a square bar), which has been calibrated on the U-1 impact testing machine and a stationary hardness gauge. This calibration results in a relation between the diameter of indentation and the energy of impact with a one-kilogram weight. Striking upon our device with a one-kilogram weight, measuring the diameter of indentation on the bar, and using the relation mentioned above, we can find the impact resistance, and the ratio between the diameters of indentations on the bar and coating enables us to determine its hardness according to GOST 18661-73.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 2, pp. 116–119, March–April, 2004.     

Homogenization of hardness distribution and distortion in high pressure gas quenching

Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching.     

高硬质NR/BR并用胶的增硬补强体系研究

研究了苯甲酸、酚醛树脂和高苯甲烯/C8树脂三类增硬补强剂对高硬质NR/BR并用胶的增硬补强效果.实验结果表明:苯甲酸增硬效果明显,尤其用量在3.0份时,胶料硬度大幅度提高,但是对其它力学性能有一定的损害;酚醛树脂的增硬效果最好,特别适合于制作邵A硬度95以上的超高硬度制品;高苯乙烯/C8树脂的增硬程度相对较小,但是所获得胶料的综合物理性能最好.     

Electrode coatings for high temperature hydrogen electrolysis

A discussion of fabrication techniques and performance testing of solid oxide components for use in hydrogen steam electrolysis is presented. Novel plasma spray techniques are utilized to deposit the thin ceramic oxide electrode, electrolyte, and interconnect layers on a planar intermetallic bipolar plate. Optimal porosity is achieved within the electrode microstructure through mixed feed techniques that are a combination of dry powder feed and liquid solution injection. The perovskite anode coatings formed from liquid precursor feedstock require post-deposition annealing in an oxygen-rich atmosphere to form the desired perovskite structures. Electrical conductivity measurements were measured for all electrodes and interconnect materials as a function of temperature to 1000 °C. Supported by the U.S. Department of Energy, Office of Nuclear Energy Science and Technology, under the DOE Idaho Operations Contract No. DE-AC07-05ID14517     

Hertzian analysis of the self-consistency and reliability of the indentation hardness measurements on superhard nanocomposite coatings

The measurement of elastic properties of superhard nanocomposite coatings can be subject to a number of possible errors, such as indentation size effects (indenter tip blunting, non-representative small volume of the material to be tested upon nanoindentation and a too small stress under the indenter which does not reach the yield stress of that material if a too low load is used), the composite effect of the system of superhard coating on a softer substrate, high compressive or tensile stress in the coatings, drifts and/or stiffness of the indenter etc. We shall present a systematic study of these possible artefacts on superhard coatings using a large range of applied loads on a number of super- and ultrahard samples. The hardness values obtained from the indentation measurements are compared with the Vickers hardness calculated from the projected area of the plastic deformation. The data will be also compared with finite element method computer modeling in order to obtain a deeper insight into the complex problems. It will be shown that reliable results can be obtained if sufficiently thick coatings are used which allows one to obtain load independent values of hardness measured at sufficiently large indentation depths. Hertzian analysis of the non-linear elastic response upon unloading provides analytical solutions that can be used in order to check if the hardness values measured on the super- and ultrahard coatings are self-consistent. In particular, it is possible to estimate the maximum tensile stress that the coatings survive without failure. This stress occurs at the periphery of the contact between the coating and the indenter and, in the case of ultrahard coatings, it can reach values in the range of tens of GPa. The results show a very good agreement with the theoretical predictions based on the Universal Binding Energy Relation.     

Phase transformation and hardness of the Ni–P–Al ternary coatings under thermal annealing

Ternary Ni–P–Al coatings were fabricated by the dual-gun rf magnetron sputtering technique. The as-deposited Ni–P–Al coatings exhibited a major Ni nanocrystalline phase (with a (111) texture) with Al and P co-deposited. After 400 °C heat treatment, various Ni_xP_y compounds, including Ni₁₂P₅, Ni₅P₂, and Ni₃P, formed within the recrystallized Ni matrix. Accordingly, the hardness of the coating increased to 10 GPa due to the Ni_xP_y precipitation. For heat treatment temperatures higher than 450 °C, Ni_pAl_q hard phases were observed in the ternary Ni–P–Al coating. A further increase in coating hardness from 10 to 12 GPa was revealed. The hardening of the annealed Ni–P–Al coatings was attributed to precipitation of Ni–P and Ni–Al compounds formed around 400 and 500 °C, respectively. A two-stage hardening in Ni–P–Al coating by Ni_xP_y and Ni_pAl_q precipitation through heat treatment was then demonstrated. Through surface analysis, the increase in surface roughness for the Ni–P–Al coating due to the formation of Ni_xP_y and Ni_pAl_q compounds was revealed.     

高氟、高盐、低硬度饮用水的处理

介绍了电渗析法除盐与水矿化技术共同应用于高氟、高盐、低硬度饮用水的处理工艺。处理后的水质符合ＧＢ５７４９－８５《生活饮用水卫生标准》，锌、锶、锂等微量元素含量达ＧＢ８５３７－８７《饮用天然矿泉水指标》。