Effect Of Chemical Etching Research Articles

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.

Direct and indirect determination of track etch parameters after sequential UV-C exposure and etching for two swift heavy ions in PADC: Production of rocket-shaped tracks

The present work aimed to study the effect of single-sided UV-C successive exposures and sequential chemical etching on the different track parameters of bulk etch rate, Vb, detector diameter, D, detector length, L, track etch rate, Vt, detection sensitivity, and etched track shape. For this, PADC detectors initially irradiated with high energy-long range ions of 7 GeV Si and 17.48 GeV Ni were used. Fission fragment irradiations were also performed before UV-C exposure to determine the PADC bulk etch rate in exposed and non-exposed UV-C sides. Track parameters of bulk etch rate, Vb, detector diameter, D, detector length, L, track etch rate, Vt, and corresponding sensitivity were determined and compared on both sides. The relative differences between the track parameters on both sides are thus determined. It was found that exposure of PADC detectors to sequential UV-C followed by etching gives a strong increase in the two etching rates, Vb and Vt. Sensitivity measurements indicate that the rate of increase of Vb is greater than that of Vt. Track parameters data by direct track cone length and indirect track diameter versus depth evidence the existence of two regions under the polymer surface. These two regions were attributed to the polymer crosslinking and degradation processes resulting from exposure to UV-C. Region 1 and Region 2 have different etching rates. Region 1 has a constant rate, while Region 2 has an increasing rate as it goes deeper. Sequential UV-C followed by etching makes it possible to generate unusual rocket-shaped (or amphora-shaped) tracks. One possible application of the described technique is the production of nuclear track membranes.

The effect of chemical etching and nanostructure additive epoxy coating technique on adhesion strength in aluminum joints bonded with nanostructure additive adhesive

In the present study, in order to increase the strength of adhesively bonded joints, the surface of the adherend was chemically etched with an anodizing treatment process at different temperatures and the surface was coated with nanostructure doped epoxy. Additionally, carbon nanostructures were added to the adhesive at different ratios to increase the strength of both the adhesive and the joint. In the study, in order to clean the surfaces of AA2024-T3 aluminum alloy plates and eliminate the oxide layer, the plates were chemically treated with a sodium hydroxide solution. Afterwards, the surfaces of these aluminum alloy plates were chemically etched with an anodizing treatment process at temperatures of 25, 40 and 60 °C. The aim here is to create different surface roughness and surface energy on the aluminum alloy surface. Epoxy pre-coating (EPC) was applied to the chemically etched aluminum alloy surfaces. Furthermore, a single-lap joint was produced by adding 0.5 %, 1 % and 2 % carboxylated carbon nanotube (CNT-COOH) by weight to the EPC and adhesive applied to the surfaces and the failure loads of the joints were examined. As a result, when the failure load obtained from the experiments was examined, it was found that chemical etching alone increased the joint strength by 22 % while the chemical etching and EPC application increased it by 46 %, the chemical etching and nanostructure doped EPC application increased it by 61 % and nanostructure addition to the adhesive increased it by 93 %. However, these increases in joint strength vary depending on the duration of the anodizing treatment process and the nanostructure additive ratio. In the chemical analyses performed to interpret these results, surface roughness test, surface contact angle test, X-ray photoelectron spectroscopy (XPS), fourier-transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and images obtained from the failure surfaces were used, respectively.

Chemical etching enhanced nanosecond pulsed laser micromachining: An experimental and numerical investigation

Nanosecond pulsed laser micromachining (PLM) under liquid confinement is a highly precise, flexible, efficient, and non-contact manufacturing process being used in widespread applications. The process efficiency of the PLM as determined by the laser ablation rate, however, often quickly reaches saturation with the increase of laser energy. This is ascribed to the screening effect of laser-induced plasma that absorbs part of incident energy. In this study, a chemical etching enhanced PLM (CE-PLM) is developed to tackle this challenge. By replacing water (H2O) with an environmentally friendly and active liquid confinement - hydrogen peroxide (H2O2), single-shot laser ablation experiments were firstly performed on different metallic materials to evaluate the considerably enhanced ablation rate. Then, the beneficial effects of H2O2 on PLM applications including micro-drilling and micro-grooving were investigated. The enhanced ablation rate and PLM efficiency were attributed to the synergistic effect of laser ablation and ultrafast chemical etching. Moreover, a physics-based model was developed to elucidate the process mechanism, with focus on revealing the contribution of chemical etching to the material removal during CE-PLM as affected by laser processing parameters. The findings of this study will contribute to enhancing the efficiency and capability of PLM techniques towards broader industrial applications.

Effect of wet chemical etching on femtosecond laser fabricated surface microstructure of polycrystalline ZnS

In this paper, wet chemical etching is employed to treat femtosecond (fs) laser fabricated surface microstructure on zinc sulfide (ZnS) to improve its surface quality (surface roughness) and regulate its size (depth/width ratio). Dilute nitric acid (HNO3) solution is selected as the etchant. First, the surface morphology of microgrooves before and after etching is observed as a function of etching time. Surface microcracks are also observed. Then, under different etchant concentrations, the size evolution of the microgrooves is measured for different etching time. Finally, an explanation for the changes in surface quality and size caused by etching is provided.

Influence of annealing and etching on physical and wetting properties of acrylic surface

The objective of this research aims to study the surface modification of acrylic for superhydrophobic applications. The acrylics were modified using annealing at 50, 75 and 100 °C for 1 h. To evaluate the effect of etching on the morphology of acrylic substrates, two different acids between tetrahydrofuran (THF) and chloroform with their concentration of 99.8 % v/v were used to etch for 1 min. Then, the annealed acrylics were etched by THF because chloroform has highly hazardous acid and low transparency after etching. The effects of annealing and wet chemical etching on morphology, optical properties and wettability can be characterized using atomic force microscopy, scanning electron microscopy, Vickers hardness tester, UV/Vis spectroscopy and water contact angle measurement. This result exhibits that the hardness of acrylic increases with the increase of annealing temperature. Furthermore, the wet chemical etching has direct affected to the wettability of acrylics due to the increasing of surface roughness.

Effect of phosphoric acid chemical etching on morphological, structural, electrical, and optical properties of porous GaAs Schottky diodes

Effect of phosphoric acid chemical etching on morphological, structural, electrical, and optical properties of porous GaAs Schottky diodes

A Fine-Grained, End-to-End Feature-Scale CMP Modeling Paradigm Based on Fully Convolutional Neural Networks

Chemical mechanical polishing (CMP) planarizes the chip surface through a synergistic effect of chemical etching and abrasive polishing, and has become increasingly essential in modern semiconductor manufacturing. For better production yield, the industry seeks an accurate CMP model to identify, localize and control surface unevenness caused by the layout dependent effect (LDE) prior to fabrication, which provides valuable information for manufacturing-friendly designs, such as accurate hotspot prediction, design-rule optimization, and smart dummy fill. However, existing models are often overly coarse-grained and inaccurate: They are unable to utilize or analyze detailed topology information in a layout design, and can only characterize the post-CMP chip surface into a rough step-height model. The prediction resolution is also constrained by the featuring window size. In this paper, we propose a novel fine-grained and end-to-end feature-scale CMP modeling paradigm based on fully convolutional neural networks. The model directly analyzes the detailed layout topology without an explicit step of featuring parameter extraction, accurately predicts the rich chip surface micro-topography at a feature-scale precision. We designed and taped-out test chips under 28nm and 40nm processes. Experiments on silicon data demonstrated our model’s accuracy improvements of 65% to 76%, as well as its cross-process-node adaptability.

Effect of the carboxyl group number of the complexing agent on polishing performance of alumina slurry in sapphire CMP

Alumina abrasive has a high polishing rate in the polishing process, but there are issues that need to be addressed with poor dispersion and poor post-polishing surface quality. This study used complexing agents with various numbers of carboxyl groups to prepare a series of alumina slurries. Scanning electron microscope images and zeta potential analysis demonstrated that the complexing agents could effectively increase the absolute value of alumina particles’ zeta potential and significantly enhance their dispersibility. Additionally, utilizing the UNIPOL-1502 polishing machine, the chemical mechanical polishing (CMP) performance of polishing slurries with complexing agents on sapphire substrates was investigated. According to the findings, as the carboxyl group count rises, material removal initially increases and subsequently declines. The material removal rate using alumina slurry added with complexing agent disodium ethylenediaminetetraacetic acid (the number of carboxyl groups is 4) can reach up to about 4.0 μm/h, which is 52% higher than that without complexing agents, while the average surface roughness of 0.96 nm can be obtained, which is 51% less than that without complexing agents. The X-ray photoelectron spectroscopy results showed that the complexing agents can react with the abrasive particles and sapphire substrates. The friction coefficient test and contact angle test revealed that slurries with complexing agents demonstrated excellent wettability and mechanical action. The sapphire surface becomes smoother as a result of the synergistic effect of chemical etching and mechanical removal.

Study on etch characteristics of magnetic tunnel junction materials using rf-biased H2/NH3 reactive ion beam

In order to etch CoFeB and MgO constituting the magnetic tunnel junction (MTJ) layer of magnetic random access memory, rf-biased reactive ion beam etching (RIBE) with a H2:NH3 gas mixture was introduced and the etching characteristics were investigated. The H2:NH3 gas mixture of 8:1 was used for rf-biased RIBE because the etch selectivity is increased with H2 percentage in the H2:NH3 gas mixture while the etch rates of MTJ materials are the highest between 2:1 and 1:1 ratio of H2:NH3 due to the synergy effect of H2 and NH3 in the etching of MTJ materials. When a high rf power was applied to the substrate (high rf-biasing) during RIBE, even though etch rates of MTJ materials were increased, the etch selectivities of MTJ materials over hard mask materials were decreased possibly due to the high physical sputtering effect. However, when small rf-biasing was added to the substrate during RIBE, improved etch characteristics such as higher etch selectivity of MTJ over the top electrode (TE) material, improved etch anisotropy of the MTJ pattern masked with TE, and a thinner sidewall residue on the MTJ pattern could be observed. The improvement in etch characteristics by the addition of small rf-biasing during RIBE is believed to be related to the increased chemical etching effect through H2/NH3 gas dissociation and the increased H/NH ratio in the plasma generated just above the substrate without increasing the physical sputtering effect. Specifically, for the substrate located on the insulating substrate holder, the charging of the substrate could be removed without using an electron emitting neutralizer by supplying electrons from the plasma generated by rf-biasing during RIBE.

High Gravimetric Capacitance MXene Supercapacitor Electrode Based on Etched Ti3C2Tx by Chemical Etching

Ti3C2T x MXene is one of the most promising electrode materials for supercapacitors, but it often suffers in poor experiment gravimetric capacitance, which limits practical applications in industry needs. Herein, etched Ti3C2T x MXene with high gravimetric capacitance is prepared by chemical etching of MXene with concentrated alkaline solution. The intercalation of K+ and the scissor role of OH− can simultaneously enlarge the interlayer spacing and cut the size of sheets, which lead to the high active‐site concentration and cation diffusion. As a result, the etched Ti3C2T x MXene displays high gravimetric capacitance of 368.1 F g−1 at 2 A g−1 and outstanding cycling stability without capacitance loss over 5000 cycles at 6 A g−1,and the surface capacitance contribution in etched Ti3C2T x MXene occurs to a greater extent compared with the pristine MXene. Moreover, the effect of chemical etching on the supercapacitor performance and energy‐storage mechanism indicates that the active‐size concentration and cation diffusion could be maximized when the chemical etching conditions are appropriate, leading to the highest performance of etched Ti3C2T x MXene. Herein, it is demonstrated that the chemical etching approach is applicable to design MXenes with high gravimetric capacitance to maximize their potential applications in energy‐storage applications and other fields.

Hierarchical leaf-like alumina-carbon nanosheets with ammonia water modification for ethanol dehydration to ethylene

A hierarchical leaf-like alumina-carbon nanosheet catalyst was prepared by a chelate-assisted co-assembly method to improve the catalytic behavior of ethanol dehydration reaction, based on the chemical etching effect of ammonia water. The uniformly dispersed leaf-like nanosheet structure possessed a relatively large specific surface area and exposed more active sites, which could promote the ethanol dehydration reaction. This catalyst was promising to obtain a higher catalytic behavior (conversion of 98.3 % and ethylene selectivity of 97.0 %) than the sample without ammonia water modification (conversion of 63.2 % and ethylene selectivity of 46.7 %) at 450 ℃. The addition of ammonia water played an essential role in influencing the formation of the leaf-like nanosheet structure and the generation of Brönsted acid active sites, which remarkably promoted the proceed of ethanol dehydration. Importantly, a direct relationship was observed between the nanosheet thickness and the alumina content. The best catalytic activity with TOF of 361.8 h−1 was obtained when the Al loading of 13.9 wt%, attributed to the suitably balanced weak/moderate acidic active sites ratio of ∼ 4.37. In-situ FTIR spectra of ethanol dehydration reaction clearly confirmed that ethanol was first converted to the intermediate product diethyl ether and then subsequently decomposed to ethylene at a higher temperature. The catalyst also maintained a good recyclability upon time on stream of 144 h at 450 ℃. This work provides an alternative way of developing non-noble metal catalyzing ethanol dehydration to ethylene.

Investigation of chemical etching and surface modification effect on the superhydrophobic, self-cleaning and corrosion behaviour of aluminium substrate

Investigation of chemical etching and surface modification effect on the superhydrophobic, self-cleaning and corrosion behaviour of aluminium substrate

Optimization of Cladding Diameter for Refractive Index Sensing in Tilted Fiber Bragg Gratings.

This work presents an experimental investigation of the effect of chemical etching on the refractive index (RI) sensitivity of tilted fiber Bragg gratings (TFBGs). Hydrofluoric acid (HF) was used stepwise in order to reduce the optical fiber diameter from 125 µm to 13 µm. After each etching step, TFBGs were calibrated using two ranges of RI solutions: the first one with high RI variation (from 1.33679 RIU to 1.37078 RIU) and the second with low RI variation (from 1.34722 RIU to 1.34873 RIU). RI sensitivity was analyzed in terms of wavelength shift and intensity change of the grating resonances. The highest amplitude sensitivities obtained are 1008 dB/RIU for the high RI range and 8160 dB/RIU for the low RI range, corresponding to the unetched TFBG. The highest wavelength sensitivities are 38.8 nm/RIU for a fiber diameter of 100 µm for the high RI range, and 156 nm/RIU for a diameter of 40 µm for the small RI range. In addition, the effect of the etching process on the spectral intensity of the cladding modes, their wavelength separation and sensor linearity (R2) were studied as well. As a result, an optimization of the etching process is provided, so that the best trade-off between sensitivity, intensity level, and fiber thickness can be obtained.

In situ STEM analysis of electron beam induced chemical etching of an ultra-thin amorphous carbon foil by oxygen during high resolution scanning

Support foils for (scanning) transmission electron microscopy ((S)TEM) samples are commonly amorphous carbon foils. State of the art (S)TEM high resolution imaging methods use ultra-thin carbon foils of only a few nm thickness, especially for imaging beam sensitive materials with low acceleration voltages and electron fluxes. In this study we analyze in situ the effect of chemical etching on a 2 nm amorphous carbon foil due to residual oxygen and by leaking in oxygen into the microscope column. We vary the vacuum level on a Nion UltraStem 100 between ultra high vacuum and that typical in TEM. This enables us to carry out a systematic investigation of chemical etching as function of both, oxygen pressure and electron flux. In addition the results of chemical etching are compared with those of sputtering from knock-on damage leading to the conclusion that chemical etching is the important cause for carbon removal from an amorphous foil at low oxygen pressures and low electron fluxes. We observe that the electron flux dependency using high resolution scanning conditions differs from the case of a resting electron beam. To interpret the results of chemical etching a scanning etching model is proposed that takes care of the specific conditions of STEM.

Effects of chemical etching and reduction activation of CeO2 nanorods supported ruthenium catalysts on CO oxidation

In this work, pristine and NaBH4 etched CeO2 nanorods supported ruthenium (Ru) catalysts were synthesized and employed to investigate the effects of chemical etching and reduction activation treatment on CO oxidation. With 1 wt% Ru loading, the CeO2 nanorods supported catalyst samples, after 6 wt% NaBH4 etching treatment, showed significantly promoted H2 consumption under 100 °C and low apparent activation energy (i.e., Ea ∼ 31.2 kJ/mol) for CO oxidation. In-situ CO-DRIFTS profiles revealed that, for the reduced sample, the observed CO adsorption at ∼ 2020 cm−1 at 40 °C may be related to a strong RuOx-CeO2 interaction induced by the NaBH4 etching treatment, which was supported by the oxygen vacancy analysis results of X-ray photoelectron spectroscopy and CO-temperature programmed desorption. The enriched surface defects on CeO2 support due to the chemical etching and reduction treatments are believed to promote the interaction between RuOx species and CeO2, which is responsible for the enhanced activity of CO oxidation.

Flame-retardant activity of ternary integrated modified boron nitride nanosheets to epoxy resin

In order to improve the fire safety of epoxy resin, ZIF-8 nanoparticle in-situ decorated boron nitride nanosheet (BN-OH/ZIF-8) is fabricated via self-assembly method and then ternary integrated BN-OH/ZIF-8/PA hybrids are prepared through the chemical etching effect of phytic acid. FTIR, XRD, XPS, TEM and TGA measurements are used to characterize the structure and morphology of the nanohybrids. The researches show that BN-OH/ZIF-8/PA not only uniformly distributed in EP matrix, but also improve the thermal stability of EP. The peak heat release rate, peak smoke production rate, total smoke production values, the fire growth index and peak CO production rate obtained from cone test are significantly decreased, demonstrating the reduction of the fire hazards of EP composites containing BN-OH/ZIF-8/PA. The nano barrier effect and catalytic activity of BN-OH/ZIF-8/PA may be conducive to suppress the release of combustible volatile products and heat, facilitate the formation of graphitized carbon layer, and protect matrix from flame damage. The ternary integrated method developed in this study explores a new way to improve the flame retardant properties of EP, thereby promoting its application range.

Surface pre-treatments of Ti-Nb-Zr-Ta beta titanium alloy: The effect of chemical, electrochemical and ion sputter etching on morphology, residual stress, corrosion stability and the MG-63 cell response

Pre-treatment methods for titanium alloys are of great importance, both as regards the treatment of the surfaces of the implant and as regards the pre-deposition phase of the coating processes and the surface modifications. We have investigated the impact of chemical, electrochemical and ion sputter etching on the surface properties, the corrosion stability and the MG-63 cell response of Ti-35Nb-7Zr-5Ta alloy. In the initial state, the samples have a mechanically polished surface. The pre-treatments that were applied led to significant morphological changes in microscale and also in nanoscale. The wettability of the pre-treated surfaces varied from hydrophilicity to hydrophobicity. Changes in contact angle were controlled by surface chemistry rather than changes in morphology and roughness. Native oxides and suboxides of alloying elements with a predominant amount of Nb2O5 were found to provide high corrosion stability of Ti-35Nb-7Zr-5Ta alloy after mechanical polishing, after chemical etching and after electrochemical etching. Significantly reduced corrosion resistance in a physiological saline solution was observed for the ion sputtered surface. A decreasing trend in the cell spreading area correlated with increasing surface roughness and decreasing polarization resistance. There is discussion of the causes of the changes in surface properties and cell behaviour.

Carrageenan assisted synthesis of morphological diversity of CdO and Cd (OH)2 with high antibacterial activity

This research reports a simple and novel method for the controlled synthesis of cadmium oxide (CdO) and cadmium hydroxide (Cd(OH)2) with different new morphologies in the presence of NaBH4 or LiBH4 as reducing agent, by using κ-carrageenan as a capping/stabilizing agent and potassium bromide as a template. The synthesized products were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The impacts of reducing agent, reaction atmosphere, and concentration of reducing agent on size and morphology of the particles were discussed. We suggested that chemical etching and Kirkendall effect play a key role in the morphology of particles, and the etch rate depends on reducing agent concentration. It was found that by increasing the concentration of the reducing agent, the intensified etching leads to an increase in the size of the particles. The results show an increase in particle size with decreasing reducing agents power. The various morphologies obtained for CdO and Cd(OH)2 such as hollow cube, macro rod, nanoplate, and macroplate were discussed based on the Kirkendall effect and chemical etching. Finally, the antibacterial activity of the synthesized nanoparticles was screened against Escherichia coli (E. coli) and Staphylococcus aureus (s.aureus). The inhibition zones were ranged from 36–47 mm and 25–47 mm for different morphologies of CdO and Cd(OH)2, respectively. Furthermore, the reactive oxygen species (ROS) production assay in the presence of bacteria was performed. The results did not show any positive result of ROS production.

In-situ DRIFTS study of chemically etched CeO2 nanorods supported transition metal oxide catalysts

• Effect of NaBH 4 chemical etching on the reducibility of CeO 2 nanorods. • CO adsorption band for polydentate carbonate is found from in situ DRITFS as a result of NaBH 4 etching. • Surface defects obtained by NaHB 4 chemical etching are critical to strong TM (TM-transition metals: Cu, Co, Ni, Fe, Mn)-CeO 2 interactions, therefore resulting in the improved low temperature catalytic activity. In this work, hydrothermally synthesized CeO 2 nanorods (CeO 2 NR) were chemically etched by strong reducing agent NaBH 4 with 0.6~30 wt% addition, and further transition metal (TM) oxides (TM: Cu, Co, Ni, Fe and Mn) were loaded on the surface modified 6 wt% NaBH 4 CeO 2 NR powder (mCeO 2 NR) to prepare mCeO 2 NR supported TM oxide catalysts. Both mCeO 2 NR supports (treated by 0.6–30 wt% NaBH 4 ) and mCeO 2 NR supported TM oxide catalysts were employed to investigate the effect of chemical etching on their surface structure, CO adsorption, CO 2 desorption and catalytic performance. Compared with pristine CeO 2 NR, one strong CO adsorption band for polydentate carbonate is found from in situ DRITFS as a result of NaBH 4 etching, which can explain the enhanced low temperature reducibility and catalytic performance of mCeO 2 NR supports and mCeO 2 NR supported TM oxide catalysts. The vibrational band signals of bicarbonate, monodentate/bidentate/polydentate carbonate and bridged carbonate are detected in all mCeO 2 NR supported TM catalysts and the effect of CO adsorption mode on CO oxidation activity is discussed.