Facile Synthesis of Fluorinated Polysilazanes and Their Durable Icephobicity on Rough Al Surfaces

Superhydrophobic Al surfaces with excellent durability and anti-icing properties were fabricated by coating dual-scale rough Al substrates with fluorinated polysilazane (FPSZ). Flat Al plates were etched using an acidic solution, followed by immersion in boiling water to generate hierarchical micro-nano structures on their surfaces. The FPSZ coatings were synthesized by grafting 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17), a fluoroalkyl silane), onto methylpolysilazane, an organopolysilazane (OPSZ) backbone. The high water contact angle (175°) and low sliding angle (1.6°) of the FPSZ-coated sample with an FAS-17 content of 17.3 wt% promoted the efficient removal of a frozen ice column with a low ice adhesion strength of 78 kPa at −20.0 °C (70% relative humidity), which was 4.3 times smaller than that of an OPSZ-coated surface. The FPSZ-coated Al surface suppressed ice nucleation, leading to a decrease in ice nucleation temperature from −19.5 to −21.9 °C and a delay in freezing time from 334 to 4914 s at −19.0 °C compared with the OPSZ-coated Al surface. Moreover, after 40 icing–melting cycles the freezing temperature of a water droplet on the FPSZ-coated Al surface remained unchanged, whereas that on the FAS-17-coated Al surface increased from −22.3 to −20.7 °C. Therefore, the durability of the polymeric FPSZ coating was superior to that of the FAS-17 monolayer coating.

Single-Step Fabrication and Characterization of Nanoscale Cu Thinfilms for Optoelectronic Applications

Nanostructured materials with optical transmittance with sufficient electrical conductivity are feasible for the transparent electrical devices and optoelectronic applications. Copper (Cu) possesses inherent superior electrical conductivity. Cu thin films on glass substrates provide the basic design understanding of the transparent electrodes for humidity sensors and solar cells applications. To understand the fundamental fabrication and electrical properties, a single-step facile fabrication approach was applied for Cu nanofilms through the DC sputtering method. Correlation of thickness of Cu nanofilms with optical and electrical properties was established. Parameters such as current, voltage, vacuum pressure, and time of coating were varied to develop different thickness of metal coating. Under optimized conditions of 10−1 torr vacuum, 1.45 KV voltage, and 4–6 min coating time, a conductive path is successfully established. A 1 min coated sample demonstrated resistance of 4000 ohm and conductance of a 6 min coated sample was raised to 56 m-mho. A higher surge of voltage assisted the production of relatively thick and uniform coatings with the crystallite size of 12 nm. The average coating thickness of 19.8 nm and roughness of 4.5 nm was obtained for a 5 min coated sample through AFM analysis. Further, it was observed that uniform nanostructured coating is essential to establish a mean free path of coated particles.

Influence of the Characteristics of Multilayer Interference Antireflection Coatings Based on Nb, Si, and Al Oxides on the Laser-Induced Damage Threshold of ZnGeP2 Single Crystal

In this work, the effect of the defect structure and the parameters of antireflection interference coatings based on alternating layers of Nb2O5/Al2O3 and Nb2O5/SiO2 layers on the laser-induced damage threshold of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm was determined. Coating deposition was carried out using the ion-beam sputtering method. The laser-induced damage threshold of the sample with a coating based on alternating layers Nb2O5 and SiO2 was W0d = 1.8 J/cm2. The laser-induced damage threshold of the coated sample based on alternating layers of Nb2O5 and Al2O3 was W0d = 2.35 J/cm2. It has been found that the presence of silicon conglomerates in an interference antireflection coating leads to a decrease in the laser-induced damage threshold of a nonlinear crystal due to local mechanical stresses and the scattering of incident laser radiation.

Corrosion characteristics of plasma spray, arc spray, high velocity oxygen fuel, and diamond jet coated 30MnB5 boron alloyed steel in 3.5 wt.% NaCl solution

30MnB5 boron alloyed steel surface is coated using different coating techniques, namely 60(Ni-15Cr-4.4Si-3.5Fe-3.2B 0.7C)-40(WC 12Co) metallic powder plasma spray, Fe-28Cr-5C-1Mn alloy wire arc spray, WC-10Co-4Cr (thick) powder high velocity oxy-fuel (HVOF), and WC-10Co-4Cr (fine) diamond jet HVOF. The microstructure of the crude steel sample consists of ferrite and pearlite matrices and iron carbide structures. The intermediate binders are well bonded to the substrate for all coated surfaces. The arc spray coated surface shows the formation of lamellae. The cross-section of HVOF and diamond jet HVOF coated surfaces indicates the formation of WC, W2C Cr, and W parent matrix carbide structures. The corrosion characteristic of the coated steel has been investigated in 3.5 wt.% NaCl solution using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDAX) techniques. The results reveal that the steel corroded in the medium despite the coatings. However, the extent of corrosion varies. HVOF coated sample demonstrated the highest corrosion resistance while arc spray coated sample exhibited the least. EDAX mapping reveals that the elements in the coatings corroded in the order of their standard electrode potential (SEP). Higher corrosion resistance of HVOF coated sample is linked to the low SEP of tungsten.

Effect of Material Composition on Thermal Stability Analysis of Coated and Uncoated FeCrAl CATCO by γ-Al2O3 Ultrasonic-Electroplating Technique

Catalytic Converter (CATCO) material become an interesting field to investigate due to the common CATCO material being ceramic material that has high brittleness than metallic materials. Therefore, this research investigates the FeCrAl metallic material as CATCO substrate that is coated by γ-Al2O3 as a washcoat, Nickel Oxide (NiO) as a catalyst. The coating analysis was performed by ultrasonic using a frequency of 35 kHz and various ultrasonic times of 1, 1.5, 2, 2.5, and 3 hours and electroplating technique by sulphamate types electrolyte using variation times of 15, 30, 45, 60, and 75 minutes, a current density of 8 A/dm2. The result shows that the raw material was consists of Fe, Cr and Al with Fe element was dominated for 74.13wt%. Coated sample by ultrasonic consists of Fe, Cr, Al, O, and C elements due to FeCrAl substrate was deposited by γ-Al2O3 powder and by electroplating technique consists of Fe, Cr, Al, O, C, Ni and Na elements due to NiO deposition as catalyst material. TGA analysis observed that the highest mass change was observed by raw material 23.39 mg and UB+EL 30 min samples for lowest mass change of 2.85 mg with a point of the reaction is 0.07 mg/min may be caused by a protective oxide layer that developed during the coating process. Therefore, the coated metallic CATCO has a promising prospect to replace the ceramic CATCO due to high thermal stability by protecting layer and low mass change.

Nano-on-micro approach for fabricating ternary metal oxy-hydroxide–based flexible supercapacitors

In the present work, we unveil a facile and effective method to directly grow Ni–Mo–Co oxy-hydroxide–based 3-dimensional hierarchical nanostructures on carbon microfibers (nano-on-micro) by using a facile hydrothermal synthesis route. Further, the electrochemical activity for directly grown fiber electrode as well as electrode formed by slurry coating of active material formed after hydrothermal reaction has been investigated. In this study, the metal ratios (nickel and cobalt) were selected to cover the wide spectrum of the concentration in order to obtain the optimum concentration for the best electrochemical performance. Electrochemical analysis of these ternary metal oxy-hydroxide–based active materials on the carbon microfiber shows significantly high electrochemical activity with a specific capacitance of 519 Fg−1 in hydrothermally activated sample and 890 Fg−1 in a slurry coated sample (at 1 Ag−1). This simple technique provides a novel method to fabricate high energy-storage devices with the advantage of being lighter and flexible and can be easily integrated for various flexible electronic applications potential applications including e-textiles, personal electronics, military apparel devices, and antimicrobial and biomedical textiles.

Exploring the Effect of a MnO2 Coating on the Electrochemical Performance of a Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Material

The effect of electrochemically active MnO2 as a coating material on the electrochemical properties of a Li1.2Mn0.54Ni0.13Co0.13O2 (LTMO) cathode material is explored in this article. The structural analysis indicated that the layered structure of the LTMO was unchanged after the modification with MnO2. The morphology inspection demonstrated that the rod-like LTMO particles were encapsulated by a compact coating layer. The MnO2 layer was able to hinder the electrolyte solution from corroding the LTMO particles and optimized the formation of a solid electrolyte interface (SEI). Meanwhile, lithium ions were reversibly inserted into and extracted from MnO2, which afforded an additional capacity. Compared with the bare LTMO, the MnO2-coated sample exhibited enhanced electrochemical performance. After the MnO2 coating, the first discharge capacity rose from 224.2 to 239.1 mAh/g, and the initial irreversible capacity loss declined from 78.2 to 46.0 mAh/g. Meanwhile, the cyclic retention climbed up to 88.2% after 100 cycles at 0.5 C, which was more competitive than that of the bare LTMO with a value of 71.1%. When discharging at a high current density of 2 C, the capacity increased from 100.5 to 136.9 mAh/g after the modification. These investigations may be conducive to the practical application of LTMO in prospective automotive Li-ion batteries.

Investigation of Liquid Metal Embrittlement during Resistance Spot Welding of Martensitic Steel with Zn Jet Vapor-Deposited Coating

Advanced high-strength steels protected by zinc coatings have contributed to a reduction in CO2 emissions in the automotive industry. However, the liquid metal embrittlement (LME) of the Fe/Zn couple induced by simultaneously acting stresses and high temperatures during resistance spot welding could be the cause of unexpected failure. We investigated the possible risk of LME in spot-welded martensitic steel with Zn jet vapor-deposited coating and its influence on weld strength. The weld nugget cross-sections were analyzed (optical microscopy, SEM-EDS), and their tensile shear strengths were compared with their uncoated counterparts. LME cracks were observed in all samples meeting the process window (6, 6.5, 7 kA) located at the edge of the sheet/electrode indentation area. The frequency and length of cracks increased with current, and the occurrence of Zn within cracks indicated the LME mechanism. The shear tests showed the Zn-coated sample underwent a decrease in tensile shear strength that was most evident at a welding current of 7 kA (13.2%). However, LME was excluded as a cause of lower strength. The decrease was attributed to the smaller nugget diameter and the thin slit of Zn coating remaining in the weld notch.

Improved in-vitro biocompatibility of LZ91 Mg–Li alloy by formation of nanostructured Ti coating through surface mechanical nano-alloying treatment

Surface mechanical nano-alloying treatment (SMNAT) was employed to fabricate a nanostructured Ti coating on LZ91 Mg–Li alloy. Microstructure, surface hardness and in-vitro biocompatibility of the Ti-coated sample were investigated in comparison with those of an untreated sample. Experimental results showed that a nanostructured Ti coating with a thickness of 35 to 60 μm was formed after SMNAT for 2 h. The average grain size in the top surface of the Ti coating was about 30 nm. The surface of the Ti coating is rougher than that of the untreated LZ91 sample, in which the values of Ra, Rq and Rz were 7.83, 9.57 and 14.85 μm, respectively. The hardness of the Ti coating top surface was about 483 HV. Cell proliferation and differentiation on Ti coated samples were enhanced relative to those on the untreated samples.

In situ polyaniline coating of Prussian blue as cathode material for sodium-ion battery

Prussian blue (PB) has great potential for use as a sodium cathode material owing to its high working potential and cube frame structure. Herein, this work reports a two-step method to synthesize PB with ascorbic acid as the ball-milling additive, which improves the electrochemical rate performance of PB during the traditional co-precipitation method. The obtained PB sample exhibited a superior specific capability (113.3 mAh g −1 even at 20 C, 1 C = 170 mA g −1 ) and a specific capacity retention of 84.8% after 100 cycles at 1 C rate. In order to enhance the cycling performance of the PB, an in situ polyaniline coating strategy was employed in which aniline was added into the electrolyte and polymerized under electrochemical conditions. The coated anode exhibited a high specific capacity retention of 62.7% after 500 cycles, which is significantly higher than that of the non-coated sample, which only remains 40.1% after 500 cycles. This development has shown a great potential as a low-cost, high-performance and environment-friendly technology for large-scale industrial application of PB.