Atomic Force Microscope Investigation on Static Nanomechanical Properties Versus Dynamic Nanotribological Evaluation of Metal–ZrN and ZrN Thin Films

The present study offers for the first time a correlation between static nanomechanical properties (nanohardness (H), elastic modulus (E), H/E and H ³/E ² ratio) and dynamic properties (resulting from nanoscratch measurements) for Metal–ZrN thin films (Inconel–ZrN, Cr–ZrN and Nb–ZrN) as well as monolayer polycrystalline ZrN thin films. Metal–ZrN thin films have a great industrial potential, as they can combine high hardness with good elasticity and toughness making them effective for wear resistant application. Nanomechanical and nanotribological properties of Metal–ZrN and ZrN thin films deposited by DC unbalanced magnetron sputtering were investigated using an atomic force microscope interfaced with a Hysitron Triboscope. The elastic recovery of thin films under a normal load applied during nanoindentation was evaluated and correlated with elastic recovery of thin films under dynamic loading during nanoscratch measurements in order to asses which film compositions provide superior wear resistance. It is demonstrated that dynamic elastic recovery measurements correlated well with those derived from static nanoindentation tests. The nanoscratch test combines both normal and tangential loading, therefore, it is expected to be an even better predictor of wear-resistance. The AFM nanoindentation and nanoscratch measurements show superior nanomechanical and nanotribological properties for Metal–ZrN thin films when compared to polycrystalline ZrN thin films.     

Corrosion and wear behaviour of ZrN thin films

Abstract

ZrN coating is an alternative candidate to replace the conventional TiN coating especially for high temperature oxidation resistance applications. ZrN coatings of varying thickness (1·5, 2·0, 2·5, 3·0 and 4·0 μm) were deposited on 316 stainless steel substrates by cathodic arc evaporation in a reactive nitrogen atmosphere. The influences of lamellae thickness on the microstructure, tribological and corrosive properties of the films were investigated. The coefficient of steady state friction of the films ranged from 0·213 to 0·659. The corrosion resistance of the coatings was tested in 1 N H₂SO₄ solution. The results indicate that the microstructure, wear and corrosion properties of the films were dependent on lamellae thicknesses and film structure.     

Sliding wear behaviour of ZrN and (Zr, 12 wt% Hf)N coatings

In the present study, the sliding wear resistances of ZrN and (Zr, 12 wt% Hf)N coatings deposited on a hardened AISI D2 tool steel by arc-physical vapor deposition (PVD) technique were examined by a ball-on-disc wear tester. Alloying of ZrN coating with 12 wt% Hf did not change the hardness significantly, but achieved an improvement on adhesion strength and dry sliding wear resistance against steel (AISI 52100-55HRC) and Al₂O₃ balls.     

稀土对AZ91镁合金耐腐蚀性能的影响

利用静态失重、极化曲线和交流阻抗测试等方法研究了AZ91合金和AZ91 RE合金在NaCl溶液中的腐蚀规律；利用金相显微镜及电子探针分析了腐蚀试样的表面和截面形貌；对腐蚀脱落产物进行了XRD鉴别。结果表明，稀土元素显著提高了AZ91合金在NaCl溶液中的耐腐蚀性能。其作用机理主要在于稀土元素的以下三个作用：改变了合金腐蚀层结构；强化了阴极相控制；影响合金腐蚀的电化学过程。三方面的综合作用，使AZ91合金在NaCl溶液中的耐蚀性有了较大的改善。     

ZrN涂层刀具的滑动磨损特性研究

山东大学摘要:采用电弧离子镀法在硬质合金刀具表面制备了厚度为2.19~5.23μm的ZrN系列涂层,测定了涂层的显微硬度,并通过划痕试验和摩擦磨损试验考察了涂层与基体的结合强度及其摩擦磨损性能。在扫描电镜下观察磨损表面形貌,结果表明:ZrN系列涂层能够显著提高硬质合金刀具的表面硬度;涂层与基体的结合强度较高,划痕临界载荷高于60N;与此同时,电弧离子镀法ZrN系列涂层可以显著改善硬质合金刀具的耐磨性能。磨损机理主要是磨粒磨损和涂层的微剥落。     

Investigation of micro-scale abrasion–corrosion of WC-based sintered hardmetal and sprayed coating using in situ electrochemical current-noise measurements

The micro-scale wear–corrosion interactions of WC-based sintered hardmetals and sprayed coatings are typically investigated by comparing the wear-rates in corrosive environments with neutral (pH 7) conditions and inferring electrochemical activity. However, for a greater understanding of the wear–corrosion interactions, there is a need to examine the repassivation kinetics during micro-abrasion tests under different pH conditions. This paper details in situ electrochemical current-noise measurements performed using a modified micro-abrasion tester to elucidate these wear–corrosion interactions for pH 7–13 conditions for sintered WC–5.7Co–0.3Cr and sprayed WC–10Co–4Cr specimens. Electrochemical measurements and SEM micrographs of worn surfaces are used to detail the degradation process. Discussion will focus on the wear–corrosion interactions present under neutral and alkaline conditions for sintered and sprayed specimens and the influence of microstructure on the electrochemical activity will be detailed.     

Structural analysis and intergranular corrosion tests of AISI 316L steel

Pure AISI 316L steel is investigated after solution heat treatment (1050 °C/H₂O) and structural sensitization (650 °C). Two quite different intergranular corrosion tests are used to determine the degree of structural sensitization due to the precipitation of secondary phases along the grain boundaries (mainly the M₂₃C₆ and σ‐phase): the oxalic acid etch test and the electrochemical potentio‐kinetic reactivation test. Generally, the dissolution of chromium‐rich carbides (M₂₃C₆) is provoked by oxalic acid etch tests, whereas the chromium‐depleted zones, in the vicinity of chromium‐rich carbides (M₂₃C₆), are attacked by electrochemical potentio‐kinetic reactivation tests. Both intergranular corrosion tests are used to determine the maximum degree of structural sensitization. Thus structural analysis by carbon replicas reveals the Laves phase, and both the M₂₃C₆ and (Cr,Mo)_x(Fe,Ni)_y phases. The results of intergranular corrosion tests are related to the findings of the structural analysis.     

Assessing the corrosion–wear behaviours of Hastelloy C276 alloy in seawater

A systematic investigation has been carried out in the present work to study the electrochemical and corrosion–wear behaviours of Hastelloy C276 alloy sliding against Al₂O₃ pin in artificial seawater, using a pin‐on‐disc tribometer integrated with a potentiostat for electrochemical control. It can be observed that the cathodic shift of open circuit potential and three order of magnitude increase of current density formed due to sliding. The total corrosion–wear loss increases with increasing applied potential. Interestingly, the total material loss at the applied potential of 0.5 and 0.9 V is more than two times of that of pure mechanical wear, confirming the synergy between wear and corrosion. And, the contributions of wear‐induced corrosion (ΔK_c) and corrosion‐induced wear (ΔK_w) are dominant, especially at higher applied potentials. Copyright © 2015 John Wiley & Sons, Ltd.     

Assessing Nanotribological Performance and Surface Energies of Inconel-ZrN,Cr-ZrN,Nb-ZrN,and ZrN Thin Films

The nanotribological performance for three groups of metal-ZrN, including Inconel-ZrN, Cr-ZrN, Nb-ZrN, and polycrystalline ZrN thin films has been investigated and results were correlated with surface energy evaluations. Metal-ZrN and ZrN thin films were deposited using direct current (DC) unbalanced magnetron sputtering and their elemental composition was investigated using X-ray photoelectron spectroscopy (XPS). Both nanomechanical and nanotribological properties were evaluated using a triboscope interfaced with an atomic force microscope (AFM) and the surface energies were calculated from the contact angle measurements. The present research reports for the first time on the nanowear behavior, surface roughness, and friction coefficients correlated with surface energies of metal-ZrN and ZrN thin films.

All metal-ZrN thin films showed improved nanotribological performance compared to the polycrystalline ZrN. Results indicate that several of the Inconel-ZrN thin film compositions have both superior nanotribological behavior and good wettability and thus have high potential use for wear resistant applications.     

Effect of Al element in Zn-Al fillers on the corrosion resistance of Cu/Al brazed joints

In this paper, we describe experimental torch welding 1061 aluminum alloy to T2 copper. The corrosion behavior and performance of Cu/Al brazed joints were systematically investigated. This investigation was conducted using an optical microscope (OM), scanning electron microscope (SEM), energy disperse spectroscopy (EDS) and other methodologies. The results showed that the corrosion resistance of brazed joints was closely associated with Al content in filler metal. The corrosion behavior in 3.5 % NaCI solution belonged to micro-electrochemical corrosion and depended mainly on electrochemical imbalance between different phases. The excessive dissolution of Al atoms led to the occurrence of the corrosion of brazed joints and the corrosion product may be Al(OH)₃, Zn(OH)₂ and ZnO. It can be also found that an increase of aluminum content controlled largely formation and distribution of α-Al phase and Al₂O₃ protective film in brazing alloys, resulting in reducing the electrochemical corrosion current density and improving the corrosion resistance and shear strength of the joint.

     

不同石墨烯添加量下MoS2基复合涂层的摩擦磨损及耐腐蚀性能

为改善MoS2基固体润滑涂层的摩擦磨损性能和耐蚀性能,制备了不同石墨烯（GE）添加量的MoS2复合涂层,利用HSR-2M摩擦磨损试验机测试了复合涂层的摩擦磨损性能,并分析了其磨损机理,通过极化曲线、交流阻抗谱（EIS）研究了涂层在3.5%NaCl溶液中的电化学腐蚀行为。试验结果表明,0.8-GE/MoS2复合涂层的摩擦磨损和耐腐蚀性能最优,其平均摩擦因数和磨损率分别为0.232和2.379×10-13 m3/(N·m),较未添加石墨烯的MoS2涂层分别降低了49.56%和43%,腐蚀速率（1.96×10-8 A/cm2）较纯MoS2涂层（5.54×10-6 A/cm2）降低了近2个数量级。石墨烯的二维片状结构具有良好的自润滑性能,在涂层中均匀分布时能有效阻隔腐蚀介质的渗透,因此,石墨烯的添加提高了MoS2基复合涂层的摩擦学性能和耐腐蚀性能,石墨烯的最优添加量为0.8%（质量分数）。     

Effects of Electrochemistry on Surface Roughness during Chemical-Mechanical Polishing of Copper

In this research, we investigated the electrochemical behavior of copper (Cu) surfaces during chemical-mechanical polishing (CMP) with alumina containing slurries. The variation of pH and the percent of oxidizer were tested against impressed anodic and cathodic potentials. The polarization curves as well as potential and current values were measured in order to investigate the effects of electrochemical interactions during polishing. The polishing performance was evaluated through friction, wear, and surface quality. Surface characterization was conducted using an atomic force microscope. The areas scanned contained surfaces having different post-CMP surface chemistry. In such, the electrochemical, chemical, and mechanical action could be revealed and compared in situ and simultaneously. Research results showed that in acidic environment, the low pH dominated the surface roughness over oxidizer and anodic current. At high pH, however, oxidizer and anodic current played important roles. As a result, an optimized polishing condition was proposed.     

等通道转角挤压对铬青铜腐蚀行为的影响

采用电化学测试和浸泡腐蚀试验研究了12道次等通道转角挤压(ECAP)处理前后铬青铜在氢氧化钠溶液中的腐蚀行为。结果表明:ECAP对铬青铜的自腐蚀电位有降低作用;挤压后铬青铜在浸泡过程中的质量损失速率高于未进行挤压粗晶铬青铜的;ECAP并未从根本上改变其电化学腐蚀机制,但却显著改变了其腐蚀形式,未挤压铬青铜的腐蚀形式为沿晶腐蚀,挤压后的腐蚀形式为均匀腐蚀。     

Electrochemical Effects on the Corrosion-Wear Behaviors of NiCrMo-625 Alloy in Artificial Seawater Solution

In this article, the tribocorrosion behaviors of NiCrMo-625 alloy sliding against an Al₂O₃ pin using a pin-on-disk tribometer have been carried out to assess the effect of electrochemical state on the corrosion–wear properties of the alloy in artificial seawater. The results shows that a cathodic shift in the open circuit potential of NiCrMo-625 alloy during tribocorrosion is confirmed and a marginal increase in corrosion current can be found under tribocorrosion compared to static corrosion. Total material loss of NiCrMo-625 alloy during tribocorrosion obviously increases with an increase in applied potential, indicating the synergistic effect between wear and corrosion. Although the corrosion rate of the alloy is significantly increased by sliding, the ratio of wear-induced corrosion to the total wear loss is not very large. The proportion of wear-induced corrosion and corrosion-induced wear to the total material loss increases obviously with an increase in potential.     

ZrN系列薄膜的研究进展

综述了近年来ZrN系列薄膜的研究现状,描述了ZrN薄膜的重要性质,介绍了以ZrN薄膜为基础的多层膜和复合膜的研究状况,分析了制备方法及工艺条件对薄膜的影响,并展望了ZrN薄膜未来的研究方向。     

Erosion– and cavitation–corrosion of titanium and its alloys

The economic and effective operation of machinery and plant involved in fluids handling is increasingly dependent on the utilisation of materials that combine high corrosion resistance and good wear resistance. This paper studies two wear–corrosion situations: (1) erosion–corrosion, where the wear is due to impacting solids in a liquid medium and (2) cavitation–corrosion, where the wear is due to impacting liquid micro-jets formed by imploding air bubbles. The characteristics of a commercially pure titanium (CP-Ti) and three alloys in erosion–corrosion and cavitation–corrosion conditions have been studied. The erosion–corrosion characteristics of each material was assessed using an impinging-jet apparatus. The tests were performed at an angle of impingement of 90°C at a particle velocity of 17 m/s and in a saline solution of 3.5% NaCl at 18°C. A series of experiments was conducted to determine the mass loss by combined erosion–corrosion before independently determining the electrochemical corrosion contribution to mass loss. It has been shown that exposure to liquid–solid erosion causes disruption of the passive film on Ti and active corrosion occurs. In contrast, the materials exhibited passive behaviour in static conditions and when exposed to a cavitating liquid only CP-Ti became active. The role of corrosion in these wear–corrosion environments on CP-Ti and Ti-alloys is discussed in this paper.     

ODS钢的电化学腐蚀性能研究

采用PGSTHT30型电化学工作站,对不同种类的ODS钢在1mol/L的硫酸溶液中的电化学腐蚀特性进行了研究,测量了极化曲线和自腐蚀电位,对腐蚀形貌进行了分析。研究表明:弥散强化合金随着Cr含量的增加,能够有效提高耐蚀性。     

多种电化学技术联合分析研究海洋微生物对钢铁的腐蚀作用

生物膜是金属发生海洋微生物腐蚀的主要作用因素之一。本文采用腐蚀电位、极化曲线、电化学阻抗谱、电偶电流等多种电化学技术联合分析,研究了天然高分子凝胶(海藻酸钙)模拟生物膜对10CrMoAl低合金钢以及1Cr18Ni9Ti不锈钢腐蚀行为的影响,得到影响海洋微生物腐蚀过程的信息,与实海实验结果相吻合,说明了各种电化学技术应用于海洋微生物腐蚀研究的可行性与局限性,多种电化学技术联合分析可以为国产的海洋用金属材料在国内海域中的微生物腐蚀研究提供详细可靠的信息。     

Assessing the Tribocorrosion Performance of Nickel–Aluminum Bronze in Different Aqueous Environments

Metallic components are frequently subjected to corrosion and tribological impacts during their service period, which results in accelerated material deterioration. In this work, a systematic investigation has been conducted to study the tribocorrosion performance of nickel–aluminum bronze (NAB) in different aqueous environments, using a pin-on-disc tribometer integrated with an electrochemical workstation. Results show that the aqueous environments considerably influence the friction and wear behavior of NAB. The friction coefficient and wear rate are highest in deionized water due to its poor lubricity. When an Al₂O₃ pin slid against NAB in 3.5% NaCl solution and seawater, a positive synergistic effect between wear and corrosion occurred. In addition, the relative contribution of corrosion–wear synergism to the total mass loss is greater in 3.5% NaCl solution than in seawater. Also of note is that applied potential plays a significant role in determining the material degradation.     

Corrosion of materials used as cutting tools of wood

According to the wood species and the type of metallic materials, the wear of woodcutting tools is very different. The metallic nature of cutting tools, the water and water-soluble components in the wood result in an electrochemical mechanism of corrosion. Of course, both a mechanical wear and an electrochemical action are responsible of the total wear of metallic tools. The objective of this study is to characterise the electrochemical action of the wood medium on the corrosion of the woodcutting tool materials.To carry out the corrosion tests, a corrosive medium is obtained by infusing wood shavings into water to obtain a juice of wood. In a second step, we have selected several metallic materials used in woodcutting and a wood specie, namely oak. Electrochemical measurements (R_p, E_corr and i = f(E) curve) were carried out during 24 h in a medium containing a water-soluble extract of oak (=an oak juice). The electrochemical behaviour of each metallic material was characterised and the morphology of the corroded surface was observed by SEM. It is shown that the electrochemical corrosion is not negligible and can be very important on cutting materials. Further experiments are in progress to characterise the effect of the mechanical wear by tribocorrosion measurements.