Surface Structure Of Substrate Research Articles

Optimization of the Zinc Deposition Interface by Sn Nanoparticles for Fast-Charging Zinc Metal Anodes.

The electrodeposition behavior of zinc metal anodes critically correlates with the electrode surface properties. The tendency for inhomogeneous deposition of zinc is more severe, especially under high current density. Herein, the surface structure of zinc and zinc deposition substrates is reconstructed with a uniform metal tin (Sn) coating via a simple evaporation method. Sn nanoparticles can serve on metal nuclei to reduce the Zn nucleation barrier and enable more nucleation sites for even deposition. Moreover, the mechanical stability of the electrode surface is improved via Zn-Sn alloying. Consequently, the uniform Zn deposition/dissolution behavior on Sn-modified two- and three-dimensional copper substrates is reflected in the stable Coulombic efficiency and reduced polarization. The Sn@Zn electrode is endowed with superior stability at a high current density (800 h at 20 mA cm-2). More encouragingly, the full cell installed with a carbon nanotube/MnO2 cathode maintains enduring stability (700 cycles) at 1 A g-1. This work enlightens metal alloy as an effective and instructive modification strategy toward stabilized zinc anodes.

Magnetization reversal of perpendicular magnetic anisotropy multilayers on polymeric substrates for flexible spintronics applications

Earlier demonstrations of spintronic functionality on flexible substrates have highlighted the potential for spintronics in flexible electronics applications. However, for device applications, the relationship between global magnetization reversal, as measured by hysteresis, and the local reversal processes of nucleation and growth of magnetic domains need to be understood for magnetic systems on flexible substrates. This study compares the local magnetization reversal behavior of perpendicularly magnetized Pt/CoFeB/Pt and Pt/Co/Pt on rigid and flexible polymeric substrates using magneto-optical Kerr effect magnetometry and microscopy. It is shown that while the magnetic hysteresis is comparable, the local details of the nucleation and field driven reversal are quite different and are attributed to the greater variability of the surface structures of the polymeric substrates, which has implications for consistency in device performance.

Effects of chemical etching on surface structure and tribological behavior of silicate substrates

Abstract This study investigated the effect of chemical etching on the surface structure and tribological behavior of silicate substrates. Silicate surfaces were etched using a mixture of nitric acid (HNO3) and ammonium bifluoride (NH4HF2) for durations ranging from 1 to 60 min. The etched surfaces were characterized using optical microscopy, scanning electron microscopy, surface profilometry, water contact angle measurements, and UV–vis spectroscopy to evaluate the changes in surface morphology, roughness, wettability, and optical properties. Tribological performance was assessed using reciprocating ball-on-plate friction tests. The results showed that increasing the etching time resulted in the formation of microscale surface features, increased surface roughness, enhanced hydrophilicity, and reduced optical transmittance. The average friction coefficient decreased with an increase in the etching time up to 30 min, beyond which a slight increase was observed. The 1-minute etched specimen exhibited the best wear resistance with the narrowest wear track and the least material removal. The improved tribological performance was attributed to the formation of a stable transfer film, reduced real contact area, and entrapment of wear debris. This study highlights the potential of chemical etching as a technique to tailor the surface structure and tribological properties of silicate materials for various applications.

Evaluating the dynamic effects of complex probiotics as cellulase replacements during fermentation of apple pomace

Apple pomace, an abundant agricultural by-product with low utilization rates, often leads to environmental pollution if not properly managed. This study aimed to enhance the nutritional value of apple pomace by comparing the effects of solid-state fermentation using complex probiotics and cellulase preparation. Additionally, the study investigated the dynamic changes in various components throughout the fermentation process with complex probiotics. The results of single-strain solid-state fermentation tests indicated that Lactiplantibacillus plantarum DPH, Saccharomyces cerevisiae SC9, and Bacillus subtilis C9 were the optimal strains for fermenting the most effective substrate combination, comprising 73 % apple pomace and 20 % millet bran. The strains (complex probiotics) and a cellulase preparation were used for the solid-state fermentation of the apple pomace mixture for nine days, respectively. The contents of acid detergent fiber, neutral detergent fiber, hemicellulose, and insoluble dietary fiber decreased by up to 9.99 %, 9.59 %, 23.21 %, and 14.34 %, respectively. In contrast, the content of soluble dietary fiber significantly increased by up to 29.74 %. Both methods reduced cellulose crystallinity and modified the substrate's surface structure, resulting in a looser arrangement. Fermentation with complex probiotics for three or six days increased the abundance of lactic acid bacteria, which comprised >87 % of the total microbial population. Concurrently, the abundance of detrimental bacteria, such as Salmonella, Acetobacter, Escherichia, and Pantoea, significantly decreased. Furthermore, fermentation with complex probiotics for six or nine days enhanced antioxidant properties, leading to a significant increase in beneficial metabolites, including amino acids, organic acids, gamma-aminobutyric acid, serotonin. In conclusion, complex probiotics can effectively substitute for cellulase preparation in the solid-state fermentation of apple pomace, with a six-day fermentation period yielding optimal results. This study provides valuable insights into enhancing the value of apple pomace in the feed industry and the effective application of agro-industrial by-products.

Short-term effects of substrate surface structure on macroinvertebrates community structure and functional characteristics

Stones are one of the important natural materials in soil bioengineering and are widely used in river ecosystem restoration projects. After stones are introduced into the river channel, they become a crucial component of the riverbed substrate. Substrate is a crucial habitat for macroinvertebrates. The surface structure of substrate plays a vital role in providing habitat for a greater diversity of macroinvertebrates, thus contributing significantly to the enhancement of riverine biodiversity. This study was conducted in the headwater streams of Changbai Mountain. Complexity was introduced to the substrate surface by adding rough treatments on concrete blocks, as well as different sizes of grooves and holes. The study found that the control substrate (GK0/GT0) took the shortest time (7 d) to establish a relatively stable macroinvertebrate community. In contrast, other treated substrates required a longer time to form relatively stable communities due to the increased available living space on the substrate surface. Overall, various diversity indices were relatively higher on rough substrates compared to smooth substrates. Specifically, at 28 d, the groove-treated substrate MT1 had the highest species richness (18.67) and Shannon-Wiener diversity index (H′, 2.85), which were 2.68 times and 1.54 times higher than the control, respectively. Similarly, at 28 d, the hole-treated substrate MK1 exhibited the highest species richness (20.35) and H′ (2.84), which were 2.90 times and 1.53 times higher than the control, respectively. With the gradient changes in groove and hole sizes, macroinvertebrate species richness, density, H′, Margalef richness index (dM), and Simpson dominance index (D) on different substrates showed an initial increase followed by a decrease trend. Additionally, attached organisms were the dominant taxa on all treated substrates, with higher densities of burrowers in hole-treated substrates and more swimmers in groove-treated substrates. Substrates with larger holes favored the settlement of larger-bodied macroinvertebrates, while substrates with small grooves had higher abundances of various-sized macroinvertebrate groups. It is evident that differences in substrate surface structure have a significant impact on macroinvertebrate diversity and functional characteristics. Therefore, in river ecosystem restoration projects, adding necessary textural structures to the substrate surface can enhance the effectiveness of river ecosystem restoration.

Fe and Cu Intercalations Enhance SERS of MoO3 through Different Mechanistic Pathways.

Surface Enhanced Raman spectroscopy (SERS) is a molecular-specific analytical technique with various applications. Although electromagnetic (EM) and chemical (CM) mechanisms have been proposed to be the main origins of SERS, exploring highly sensitive SERS substrates with well-defined mechanistic pathways remains challenging. Since surface and electronic structures of substrates were crucial for SERS activity, zero-valent transition metals (Fe and Cu) were intercalated into MoO3 to modulate its surface and electronic structures, leading to unexceptional high enhancement factors (1.0×108 and 1.1×1010 for Fe-MoO3 and Cu-MoO3 , respectively) with decent reproducibility and stability. Interestingly, different mechanistic pathways (CM and EM) were proposed for Fe-MoO3 and Cu-MoO3 according to mechanistic investigations. The different mechanisms of Fe-MoO3 and Cu-MoO3 were rationalized by the electronic structures of the intercalated Fe(0) and Cu(0), which modulates the surface and electronic structures of Fe-MoO3 and Cu-MoO3 to differentiate their SERS mechanisms.

Deep eutectic solvent cocktail enhanced the pretreatment efficiency of lignocellulose

Pretreatment of lignocellulosic biomass by breaking down its complex structure is an essential step to facilitate enzymatic hydrolysis of lignocellulose and subsequent bioethanol fermentation. Herein, an eco-friendly pretreatment strategy was developed by applying deep eutectic solvent (DES) cocktail. Attributing to the synergistic effect of two DESs (e.g., betaine-glycerol and choline chloride-oxalic acid (or choline chloride-acetamide)), an impressive 89.51% digestibility for glucan and 75.43% for xylan were achieved. Characterization of pretreated corn stover showed that DES cocktail changed substrate surface structure and enlarged structure pores, which could improve the accessibility of cellulase. The pretreated corn stover was also employed in ethanol fermentation and achieved the yield of 73.35%. Recycling experiments demonstrated the potential reusability of DES cocktail in a sustainable manner towards various biomass sources. These findings highlight the effectiveness and versatility of the developed DES cocktail pretreatment method, paving the way for sustainable bioethanol production from lignocellulosic feedstocks.

Growth of freestanding GaN crystals on three-dimensional mesh porous substrates by HVPE

The effect of two-step etching on a substrate surface structure was investigated, and the nucleation mechanism and dislocation evolution of HVPE-grown GaN on porous structures were studied in depth.

Controlling the structure of spin-coated multilayer ethylcellulose/hydroxypropylcellulose films for drug release

Porous phase-separated ethylcellulose/hydroxypropylcellulose (EC/HPC) films are used to control drug transport out of pharmaceutical pellets. Water-soluble HPC leaches out and forms a porous structure that controls the drug transport. Industrially, the pellets are coated using a fluidized bed spraying device, and a layered film exhibiting varying porosity and structure after leaching is obtained. A detailed understanding of the formation of the multilayered, phase-separated structure during production is lacking. Here, we have investigated multilayered EC/HPC films produced by sequential spin-coating, which was used to mimic the industrial process. The effects of EC/HPC ratio and spin speed on the multilayer film formation and structure were investigated using advanced microscopy techniques and image analysis. Cahn-Hilliard simulations were performed to analyze the mixing behavior. A gradient with larger structures close to the substrate surface and smaller structures close to the air surface was formed due to coarsening of the layers already coated during successive deposition cycles. The porosity of the multilayer film was found to vary with both EC/HPC ratio and spin speed. Simulation of the mixing behavior and in situ characterization of the structure evolution showed that the origin of the discontinuities and multilayer structure can be explained by the non-mixing of the layers.

Wetting behavior and mechanical properties of Sn-10Sb solder/Ni-plated Cu system with different surface structures

The Sn-10Sb alloy is a high-temperature lead-free solder for soldering with Cu substrates. It often causes brittle solder joints and poor reliability due to the generation of an over-thick interfacial layer. Adding Ni plating to Cu substrates can suppress the generation of an excessively thick interfacial layer. This paper investigated the wettability and bonding strength of two different surface structures of Ni-plated Cu substrates with Sn-10Sb solder. Sn-10Sb solder exhibited a contact angle of 69° on the rough Ni-plated Cu substrate and 80° on the smooth one. TEM and XPS analyses demonstrated that the interfacial reaction product between the Ni-plated Cu substrate and the solder was (Cu, Ni)6Sn5. The finer grains on the smooth Ni-plated surface inhibit the diffusion of Cu atoms into the solder and the slower the interfacial reaction rate, which is more conducive to the generation of stable (Cu, Ni)6Sn5 phase. Therefore, the bonding strength ratio between the Ni-plated Cu substrate with a smooth surface and the solder is better.

Evaporation of Saline Droplets on a Superhydrophobic Substrate: Formation of Crystal Shell and "Legs".

We studied the evaporation-driven crystallization in the droplets of sodium acetate anhydrous (CH3COONa) aqueous solution, which were deposited on superhydrophobic substrates. The results reveal distinct crystallization behaviors between saturated and unsaturated droplets under identical experimental conditions. Specifically, unsaturated droplets could form a quasi-spherical crystal shell on the superhydrophobic substrate, while saturated droplets could develop crystal legs between the droplet and substrate when the crystal shell formed. Subsequently, the saturated droplet was lifted off the substrate by the growing crystal legs. The formation of crystal shell was closely associated with the evaporation from the droplet surface and the internal convection inside the droplet. The formation of crystal legs was induced by the heterogeneous nucleation effect caused by the substrate of SiO2 nanoparticles. These findings provide valuable insights into regulating the morphology of salt crystallization through adjustments in salt solution concentration and substrate surface structure.

Hydrogen Evolution Reaction on AuNi Surface Alloy Formed on Single Crystal Au Electrodes

AbstractThe hydrogen evolution reaction (HER) on Au with high chemical stability is activated by alloying it with Ni. We evaluated the HER activity of the AuNi surface alloy prepared at different alloying temperatures on single‐crystal Au electrodes in 0.05 M H2SO4. The potential cycle, including the region of Ni oxidative dissolution, further enhanced the HER activity by dealloying Ni, and the activity depended on the surface structure of the Au substrate in the following order: AuNi/Au(100)<AuNi/Au(111)<AuNi/Au(110). The surface structure and atomic composition were investigated using X‐ray photoelectron spectroscopy and surface X‐ray diffraction. Surface structural analysis revealed that the dissolution of Ni from the AuNi surface‐alloy layer resulted in a decrease in the atomic occupancy of the topmost surface layer. Ni dealloying creates low‐coordination Au sites on the AuNi surface alloy, which activates the HER.

Fabrication and Characterization of Ti/TiC Composite Layers by an Electron-Beam Surface Modification

In this study, the possibilities for modification and improvement of the surface structure and properties of titanium substrates by a formation of composite Ti/TiC layers are presented. The layers were fabricated by a two-step electron-beam surface modification technique. The first step consists of injection of C powder within the pure Ti substrates by electron-beam alloying technology. The second step is the refinement and homogenization of the microstructure by the electron-beam remelting procedure. During the remelting, the speed of the motion of the samples was varied, and two (most representative) velocities were chosen: 5 and 15 mm/s. Considering both speeds of the motion of the specimens, a composite structure in the form of fine TiC particles distributed within the base titanium matrix was formed. The remelting speed of 5 mm/s led to the formation of a much thicker composite layer, where the TiC particles were significantly more homogeneously distributed. The results obtained for the Vickers microhardness exhibit a significant increase in the value in the mentioned mechanical characteristic in comparison with the base Ti substrate. In the case of the lower speed of the motion of the specimen during the remelting procedure, the microhardness is 510 HV, or about 2.5 times higher than that of the titanium substrate. The application of a higher speed of the specimen motion leads to a decrease in the microhardness in comparison with the case of lower velocity. However, it is still much higher than that of the base Ti material. The mean microhardness of the sample obtained by the remelting speed of motion of 15 mm/s is 360 HV, or it is 1.8 times higher than that of the base material.

Optimization of the Surface Structure of the SiC Substrate for SiC-Ni Melt-bonding Using Simulation by Phase-Field Method

When SiC is melt-bonded with Ni electrode, a regrowth layer containing C is formed due to the dissolution of C into the molten NiSi, which deteriorates the electrical properties. We found that the regrowth layer can be suppressed by giving the surface of the SiC substrate wavy shape. The wavy-shape substrate with appropriate periodic length and amplitude lead to the suppression of regrowth layer at the bottom of the groove. The mechanism of the suppression of the regrowth layer is that the condensation of NiSi in the grooves of the substrate causes the decrease of undercooling by decreasing the equilibrium melting point. Thinner the groove is, higher the condensation of NiSi becomes, however, further thinning of the groove reduces the curvature at the bottom of the groove and increases the melting point due to the Gibbs-Thomson effect. This effect cancels the lowering of the melting point due to the NiSi condensation, making it difficult to suppress the regrowth layer. There is an optimum range of periodic length and amplitude of the substrate surface for suppressing regrowth layer. The substrate shape with a periodic length of 9.4 μm and an amplitude of 0.92 μm was most effective to suppress the regrowth layer.

Fractal dimensions of blast-cleaned steel surfaces and their effects on the adhesion of polymeric foil systems with integrated pressure-sensitive adhesives

Morphology and structure of substrate surfaces are crucial parameters for the establishment of reliable protective layers as they determine the adhesion of the protective layer to the substrate. Insufficient adhesion will promote unwanted effects, namely delamination and blistering. This applies as well to protective hybrid-layers, consisting of a polymeric foil bonded to the substrate (usually steel) by means of an integrated pressure-sensitive adhesive. Numerous parameters are known to characterize the morphology of metal substrates. In this study, mild steel samples were prepared using dry-blast cleaning with abrasive materials (metallic, minerals) of different particle shapes and particle sizes to investigate the impact of surface profile parameters on the adhesion of polymeric foil systems (PFS). For this purpose, 2D profiles were taken from a total of 12 surface configurations with a digital contact profilometer. Fractal dimensions were estimated based on these recorded profiles using the box-counting method. For comparison, conventional roughness parameters were measured as well. Tests with a pull-off strength testing device were performed on the applied PFS to quantify its adhesion to the substrates. The estimated pull-off tensile strength values were correlated with the estimated fractal dimensions. Design of Experiment (DoE) was applied to the test design in order to establish statistically sound relationships. Using a linear correlation model, it could be shown that fractal dimensions were suitable for quantifying the adhesion with a significantly higher accuracy than commonly used substrate (roughness) parameters.

Effect of Pretreatment by Freeze Vacuum Drying on Solid-State Anaerobic Digestion of Corn Straw

As a common agricultural waste, corn straw (CS) has a refractory structure, which is not conducive to anaerobic digestion (AD). Appropriate pretreatment is crucial for addressing this problem. Thus, freeze vacuum drying (FVD) was proposed. In this study, fresh CS (F-CS) pretreated (5 h, −40 °C) by FVD and naturally dried CS (D-CS) were compared. Differences in substrate surface structure and nutrient composition were first investigated. Results show that a loose and porous structure, crystallinity, and broken chemical bonds, as well as higher proportions of VS, C, N, cellulose, hemicellulose, and crude proteins in F-CS show a potential for methane production. Besides, process performance and stability were also examined in both high (4, VS basis) and low (1, VS basis) S/I ratio AD. A higher degradation ratio of hemicellulose as well as richer dissolved microbial metabolites, coenzymes, tyrosine-like proteins, and hydrolysis rate of particulate organic matter in the F-CS system enhanced the efficiency of methane conversion. The cumulative methane yield increased from 169.66 (D-CS) to 209.97 (F-CS) mL/gVS in the high S/I ratio system (p = 0.02 < 0.05), and 156.97 to 171.89 mL/gVS in the low S/I ratio system. Additionally, 16S-rRNA-gene-based analysis was performed. Interestingly, the coordination of key bacteria (Clostridium_sensu_stricto_1, Bacillus, Terrisporobacter, Clostridium_sensu_stricto_7, Thermoclostrium, UCG-012, and HN-HF0106) was more active. Poorer Methanosarcina and Methanomassiliicoccus as well as richer Methanobrevibacter and Methanoculleus stimulated the co-relationship of key archaea with diverse methanogenesis pathways. This study aims to verify the positive effect of FVD pretreatment on AD of CS, so as to provide a reference for applications in waste management.

Improving the high-temperature adhesion strength between an Al/polysiloxane coating and a polyimide/carbon fiber substrate by a thermal pre-treatment step and structural design

In this study, the adhesion strength between a low-emissivity Al/polysiloxane coating and the polyimide/carbon fiber substrate at high-temperatures was successfully enhanced. The surface microstructure, adhesion, thermal properties, and optical performance of the samples were measured by scanning electron microscopy, tensile testing, simultaneous thermal analysis, infrared spectroscopy, and infrared thermal imaging. The coating structural analysis results showed that the emissivity of the top of the coating was lower than that of the bottom owing to the high enrichment ratio of Al powder with good infrared reflectance on the top. The thermal stability of the polyimide/carbon fiber substrate was studied to explore the effects of high temperature on the substrate surface structure and composition. Moreover, the failure mechanism of the adhesion strength between the coatings and substrate was explained, and the adhesion strength after being heated at 500 °C for 30 min was successfully enhanced using a resin intermediate layer and thermal pre-treatment step. Substrate pre-treatment at 500 °C for 6 min increased the adhesion strength by 3.5 ± 0.4 MPa because of the polysiloxane resin intermediate layer. The adhesion strength increased from 0.5 ± 0.4 to 5.0 ± 0.4 MPa when the pre-treatment time of polyimide/carbon fiber increased from 0 to 6 min. The potential applications of carbon fiber on the infrared stealth and energy saving fields at high temperatures might be improved by adding high-temperature resistant low-emissivity organic coatings to reduce infrared absorption and radiation.

Enhancement of Adhesion of Diamond Coating on Cemented Carbide by Laser Modified Substrate Surface Structure Pretreatment

Enhancement of Adhesion of Diamond Coating on Cemented Carbide by Laser Modified Substrate Surface Structure Pretreatment

Growth, coalescence, and etching of two-dimensional overlayers on metals modulated by near-surface Ar nanobubbles

The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates, especially involving the overlayer-substrate interaction. By using in situ surface measurements, we demonstrate that the overlayer-substrate interaction can be tuned by doping near-surface Ar nanobubbles. The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles, accompanying by an “anisotropic to isotropic” growth transformation. On the substrate containing near-surface Ar, the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference, and thus, the morphology of the two-dimensional (2D) overlayer exhibits a round-shape. Especially, the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction, which is barely observed in the synthesis of 2D materials. This can be attributed to the immigration lifetime and diffusion rate of growth species, which depends on the overlayer-substrate interaction and the surface catalysis. Furthermore, the “round to hexagon” morphological transition is achieved by etching-regrowth, revealing the inherent growth kinetics under quasi-freestanding conditions. These findings provide a novel promising way to modulate the growth, coalescence, and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer-substrate interaction, which contributes to optimization of large-scale production of 2D material crystals.

Improving of Surface Quality of Metal Reflector Mirrors Machined by Single Point Diamond Turning

Improving the technology of diamond turning of aluminum alloys is of great importance for expanding the application areas of metal-optical products based on aluminum in aerospace technology. The aim of this work was to study the effect of surface inhomogeneities of the initial aluminum alloy substrates on their optical and mechanical characteristics and to determine ways of improving the quality of aluminum reflector mirrors manufactured using nanoscale single point diamond turning. The investigated reflector mirrors were made from AMg2 aluminum alloy. The optical surface treatment was carried out on a precision turning lathe with an air bearing spindle using a special diamond cutter with a blade radius of ≤ 0.05 μm. The analysis of the surface structure of the AMg2 alloy substrates was carried out by scanning electron microscopy / electron microprobe. The quality control of the surface treatment of the manufactured reflector mirrors was carried out by atomic force microscopy. The reflectivity and radiation resistance of these samples were also investigated.It is shown that an important problem in the manufacture of optical elements from aluminum alloys is the inhomogeneity of the structure of the initial material, associated with the presence of intermetallic inclusions. Heat treatment of the AMg2 alloy substrates at T ≥ 380 °C makes it possible to improve the quality of surface and the radiation resistance of aluminum mirrors both by removing mechanical stresses and by partially homogenizing the starting material. The optimum is heat treatment at the maximum allowable temperature for the AMg2 alloy T = 540 ºС, as a result of which there is a complete disappearance of intermetallic inclusions with an increased magnesium content. The use of high-temperature heat treatment of AMg2 alloy substrates allows, in comparison with unannealed samples, to reduce the surface roughness from 1.5 to 0.55 nm, to increase the reflectivity of mirrors at a wavelength of 1064 nm from 0.89 to 0.92, and to increase the laser damage threshold from 3.5 to 5 J / cm2.