This study shows that AlSi10Mg parts with an extremely fine microstructure and a controllable texture can be obtained through selective laser melting (SLM). Selective laser melting creates complex ...functional products by selectively melting powder particles of a powder bed layer after layer using a high-energy laser beam. The high-energy density applied to the material and the additive character of the process result in a unique material structure. To investigate this material structure, cube-shaped SLM parts were made using different scanning strategies and investigated by microscopy, X-ray diffraction and electron backscattered diffraction. The experimental results show that the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells. Consequently, the AlSi10Mg SLM products have a high hardness of 127±3 Hv0.5 even without the application of a precipitation hardening treatment. Furthermore, due to the unique solidification conditions and the additive character of the process, a morphological and crystallographic texture is present in the SLM parts. Thanks to the knowledge gathered in this paper on how this texture is formed and how it depends on the process parameters, this texture can be controlled. A strong fibrous 〈100〉 texture can be altered into a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied.
A trade-off between strength and corrosion resistance is usually found in Al alloys. In this work, we attempt to overcome the strength-corrosion trade-off in an Al-1wt%Mg binary alloy by a surface ...mechanical treatment. Microstructure and chemical composition of AlMg alloy with and without treatment were investigated by using SEM, TEM, XRD, SIMS and XPS techniques. After treatment, ultrafine grains with an average size of 433 nm are presented in the topmost ~5 μm layer, showing a significant grain refinement. The results of SIMS and XPS indicate that the surface segregation of Mg is evident for the coarse-grained sample, while for the treated sample Mg is absent on the topmost 10 nm-thick surface layer. The hardness increased by ~200 % and the corrosion rate decreased by ~60 %. Deformation-induced grain refinement, low-angle grain boundaries, strain strengthening effects and the redistribution of Mg element in the surface layer contribute to the simultaneous improvement of strength and corrosion resistance. Such plastic deformation treatment provides a novel strategy for effectively improving the strength and corrosion resistance of AlMg alloys.
Gradient structure fabricated by surface mechanical treatment overcomes the trade-off between strength and corrosion resistance in Al-1wt%Mg alloy. Deformation-induced grain refinement and depletion of Mg in the surface layer contribute to the simultaneous improvement of strength and corrosion resistance. Display omitted
•Ultrafine grains averaging 433 nm at the topmost surface fabricated in Al-1wt%Mg•Hardness increases by ~200 %, corrosion rate decreases by ~60 %.•Overcoming the strength-corrosion trade-off in Al-1wt%Mg alloy.
Aggregates containing iron sulfide are vulnerable to oxidation processes that may cause an internal sulfate attack and rust formation in concrete, leading to severe deterioration. This research made ...an effort to propose appropriate protection measures to prevent these issues associated with iron sulfide-containing aggregates. The efficacy of surface treatments with various functional mechanisms in reducing the rate of oxidation and associated concrete deterioration was investigated. All the studied surface treatments, except hydrophobic impregnation, were able to reduce the oxidation rate and related damage. Nevertheless, the degree of protection depends upon the surface treatment types. Surface treatments with epoxy coating and a crystalline waterproof system exhibited outstanding performance in controlling the damage. Nonetheless, the specimens treated with hydrophobic impregnation showed severe damage. An extensive investigation was conducted to comprehend the mechanism that resulted in such behavior, and the outcomes are reported in this paper.
•The oxidation of iron sulfide in aggregates causes internal sulfate attack and rust.•Methods to prevent concrete damage from iron sulfide-bearing aggregate are proposed.•The effectiveness of various surface treatments in reducing damage is investigated.•Crystalline waterproofing and epoxy coating are effective in reducing damage.•Hydrophobic impregnation exhibited negative behavior and severe damage.
Piezoresistive pressure sensors are deemed as a critical sensing component in wearable devices, and various polymer assembly with different structures are selected as flexible sensor substances. In ...this paper, low cost, commercial three-dimensional polyester non-woven fabrics (PNWFs) were employed as the sensor substrate whose advantages were elucidated through mathematical analysis. The effects of structure parameters (fiber diameter and fiber volume fraction) of 3D non-woven sensors on the sensing performance were analyzed. Reduced graphene oxide (rGO) and polydimethylsiloxane (PDMS) were deposited on the substrate to form the piezoresistive pressure sensor with a high conductivity 0.29 S/m after thermal reduction treatment. The assembled pressure sensors in general possessed excellent sensing characteristics, including excellent sensitivities of compressing (S = 23.41 kPa−1) and bending (S = 35.37 kPa−1), short response time (120 ms) and recovery time (240 ms), favorable resolutions (18 Pa under compressing and 21 Pa under bending) and low hysteresis value (0.8%). Finally, the pressure sensor has demonstrated successfully in detecting various physiological activities and subtle physiological signals, including walking, running, elbow flexing, finger bending, breathing, speaking and blood pulse beating.
•Interface engineering for surface-cleaned SSE was proposed via HMP.•Li2CO3 impurity was removed and interfacial resistance was reduce to 28.15 Ω·cm2.•Symmetric cell exhibits an excellent cycling ...stability for 1200 h.•Superior capacity retention remains 89.5% after 500 cycles (0.2C).•The work is potentially utilized for large-scale industrial production of SSLBs.
Solid-state lithium batteries (SSLBs) with garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZTO) are one of the most promising candidates for next-generation energy storage system due to their high safety and high stability against Li metal. However, the poor interfacial contact of Li/LLZTO interface induced by Li2CO3 surface impurity hinders its practical application. Herein, interface engineering enabled by high-speed mechanical polishing (HMP) method is proposed to remove impurities on porous LLZTO surface and retrieve its lithiophilicity. The strong centrifugal force provided by the high rotation speed promotes the complete removal of Li2CO3 impurity and accelerates the Li-ion transport at Li/LLZTO interface, reducing the interfacial resistance to 28.15 Ω·cm2 under ultraclean interface, which is comparable to the state-of-the-art surface treatments. Symmetric Li cells assembled with high-speed (5000 rpm) polished LLZTO exhibit a critical current density of 1.91 mA·cm−2 and excellent cycling stability for 1200 h at 0.1 mA·cm−2. SSLBs with LiFePO4 cathode achieve a superior stable cycling performance with a high discharge capacity of 138.6 mA·h·g−1 and a capacity retention of 89.5% after 500 cycles (0.2C). This work guides a new understanding for obtaining lithiophilic Li/LLZTO interface through a simple, low-cost, and high-efficient polishing strategy, which is potentially utilized for large-scale industrial production of SSLBs.
Perovskite light emitting diodes suffer from poor operational stability, exhibiting a rapid decay of external quantum efficiency within minutes to hours after turn-on. To address this issue, we ...explore surface treatment of perovskite films with phenylalkylammonium iodide molecules of varying alkyl chain lengths. Combining experimental characterization and theoretical modelling, we show that these molecules stabilize the perovskite through suppression of iodide ion migration. The stabilization effect is enhanced with increasing chain length due to the stronger binding of the molecules with the perovskite surface, as well as the increased steric hindrance to reconfiguration for accommodating ion migration. The passivation also reduces the surface defects, resulting in a high radiance and delayed roll-off of external quantum efficiency. Using the optimized passivation molecule, phenylpropylammonium iodide, we achieve devices with an efficiency of 17.5%, a radiance of 1282.8 W sr
m
and a record T
half-lifetime of 130 h under 100 mA cm
.
The low-temperature performance (LTP) of AB3.42-type La–Y–Ni hydrogen storage alloy was studied by methods of element substitution and surface treatment. The effect of Mn-additive on LTP of ...La1·3Ce0·5Y4·2Ni19.5-xMnxAl (x = 0, 0.2, 0.5) was systematically investigated. Electrochemical studies showed that Mn-additive deteriorated the LTP of the alloy by reducing platform pressure, deteriorating kinetic performance and forming more oxides on the alloy surface. RE-substitution and hot alkali-ultrasonic treatment of La1.3RE0.5Y4·2Ni19·5Al (RE = Ce, Sm, Nd) alloys were applied to further optimize the LTP. The maximum discharge capacity and capacity retention at the 100th cycle of La1·3Ce0·5Y4·2Ni19·5Al alloy were 252.1 mA h/g and 87.1% at 243 K, respectively. Furthermore, the LTP of RE-substitution alloys at 243 K was conspicuously improved by surface treatment, which were raised from 214.7 mA h/g to 301.1 mA h/g by Sm-substitute, from 220.9 mA h/g to 303.9 mA h/g by Nd-substitute and from 252.1 mA h/g to 254.8 mA h/g by Ce-substitute.
•The Ce2Ni7 and Gd2Co7-type phase own diverse electrochemical characteristics under different temperatures.•Mn-additive reveals negative effect on the low temperature dischargeability of the alloy.•Surface treatment promotes the low temperature dischargeability of the Mn-free alloy.
RETRACTION: J. L. Calvo‐Guirado, A. J. Ortiz‐Ruiz, B. Negri, L. López‐Marí, C. Rodriguez‐Barba, F. Schlottig, “Histological and histomorphometric evaluation of immediate implant placement on a dog ...model with a new implant surface treatment”, Clinical Oral Implants Research 21, no. 3 (2010): 308–315, https://doi.org/10.1111/j.1600‐0501.2009.01841.x
The above article, published online on 9 February 2010 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal's Editor in Chief, Lisa J. A. Heitz‐Mayfield; and John Wiley & Sons Ltd.
The retraction has been agreed due to concerns raised by third parties on the data presented in the article. Several flaws and inconsistencies between results presented and experimental methods described were found. Specifically, Figure 5b is described as control group, but it used in Figure 6b to represent the test group. Figure 7c is described as control group, but it used in Figure 8a to represent the test group. Accordingly, the editors consider the findings of this article unreliable and the conclusions to be invalid. The authors have been informed of the decision to retract the article. The corresponding author J. L. Calvo‐Guirado disagrees with the decision of retraction. Co‐authors A. J. Ortiz‐Ruiz and F. Schlottig state that they were unaware of these issues and concur with the decision for retraction based on the presented findings. The remaining co‐authors were not available for a final confirmation of the retraction.
Since the advent of additive manufacturing (AM) (also called 3D-printing), substantial progress has been achieved in technological advances in the processes and micro/macro characteristics of the ...components. However, this rapidly evolving field is faced with some barriers to industrial adoption, especially in the case of metals processing. Poor surface quality and surface topography imperfections, which are inherent in metal AM, are among the main drawbacks hindering AM broad industrial adoption. This issue cannot be addressed only by AM process optimization due to the intrinsic complexity of the process. Therefore, effective surface post-treatment methods are required to enhance the surface quality of the final parts for both external and hard-to-reach internal surfaces. Considering the importance and urgent need for surface modification of AM metals, this review aims to provide a broad overview of the existing research endeavors as well as gaps and opportunities in the surface enhancement of AM metals, with a focus on solution-based approaches to improve surface roughness of complex metal 3D-printed parts with intricate surfaces and evaluate the effect of these approaches on the functional properties for end-use applications. Assessing the effectiveness of the surface modification techniques, the present paper further provides the research needs to fulfill the performance-impacting knowledge gap for AM industrial adoption and further expansion of surface treatment methodologies for improved surface finish of complex metal printed parts.
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