Etching Solution Research Articles

Evaluation of the Effect of Two Surface Treatment Methods on Shear Bond Strength between Porcelain Veneer and Two Different Zirconia Blocks

Introduction: The aim of the study was to test the effect of two surface treatment methods on shear bond strength between a porcelain veneer and two different zirconia blocks. Materials and Methods: Sixty disk-shaped zirconia samples (30 samples of Novi brand and 30 samples of Rainbow brand) were used (diameter of 10 mm and thickness of 4 mm). Based on surface treatment, the samples were randomly divided into 3 groups: control, air-particle abrasion, and Zircos-E Etching Solution. Using the metal mold, the porcelain was veneered on the zirconia surface and then fired. Then, all samples were subjected to shear bond strength testing using a universal testing machine at a speed of 1 mm/min until breaking. Results: There was a statistically significant difference between the mean variable shear bond strength of the control group and two other groups, so the shear bond strength in the control group was less than in both groups. And there was no statistically significant difference between the mean variable of shear bond strength in the two groups of “airborne particle abrasion” and “Etching”. There was a statistically significant difference between the mean shear bond strength of the two types of zirconia samples and this amount was lower in Novi than in Rainbow. There was also no interaction between the type of surface preparation and the type of zirconia. Conclusion: It can be concluded that surface preparation with air particle abrasion and etching increases the shear bond strength of zirconia to porcelain veneer and the shear bond strength of zirconia and porcelain veneer is affected by the type of zirconia.

A Study on the Leaching and Recovery of Lithium by Reaction between Ferric Chloride Etching Solution and Waste Lithium Iron Phosphate Cathode Powder

A Study on the Leaching and Recovery of Lithium by Reaction between Ferric Chloride Etching Solution and Waste Lithium Iron Phosphate Cathode Powder

Study on the Preparation of Oxygen Reduction Catalyst for Fuel Cell by NH3 Heat Treatment ZIF-8

The development of catalyst in fuel cell is seriously hampered due to high preparation costs and complex processes. In this paper, a graded porous N-doped carbon material was prepared using NH3 heat treatment ZIF-8, and its microstructure and electrochemical behavior. were characterized and analyzed. It is found that the chemical etching process can introduce mesoporous (2-50nm) or macropores (>50nm) into ZIF-8 to form. a graded porous structure, and the pore size of ZIF-8 can be effectively adjusted by controlling the pH of the etching solution. The NH3 heat treatment can effectively adjust the pore structure in carbon materials, increase the number of micropores (<2nm) and mesopores in the materials, and increase the specific surface area of the materials. NH3 can be used as an N source to dope the material with a certain amount of N. It can also regulate the conversion of pyridine N and pyrrole N in the carbon material to the more stable graphite N, and the pore structure and N doping content of the carbon material can be reasonably controlled by controlling the temperature of NH3 heat treatment. The N-C@2. 5pH-1000 prepared in this paper has excellent electrocatalytic performance, similar oxygen reduction reaction (ORR) activity and better cycling stability than commercial Pt/C catalysts. The synthetic strategy proposed in this paper provides a new idea for the preparation of efficient and inexpensive fuel cell catalysts.

Electron-enhanced SiO2 atomic layer deposition at 35 °C using disilane and ozone or water as reactants

Electrons can enhance SiO2 atomic layer deposition (ALD) at low temperatures using disilane (Si2H6) and either ozone (O3/O2) or water (H2O) as reactants. SiO2 electron-enhanced ALD (EE-ALD) was demonstrated at 35 °C by exposing the sample to sequential electron, oxygen reactant, and Si2H6 exposures. The reaction sequence was electron beam exposure for 3 s, purge for 5 s, O3/O2 or H2O exposure at 0.5–1.0 Torr for 3 s, purge for 10 s, Si2H6 exposure at 100 mTorr for 1 s, and purge for 15 s. The electron exposure was an electron current of ∼150 mA for 3 s. The electrons were produced by a hollow cathode plasma electron source typically operating with a grid bias of ≈−300 V. These electrons could irradiate a sample area of ∼2 × 2 cm2. In situ spectroscopic ellipsometry measurements determined that SiO2 EE-ALD films nucleated rapidly and deposited linearly versus number of EE-ALD cycles. The SiO2 EE-ALD growth rate was 0.89 Å/cycle using O3/O2 and 0.88 Å/cycle using H2O. The SiO2 growth rate was also self-limiting at higher electron and Si2H6 exposures. In addition, SiO2 EE-ALD films were grown by changing the reaction sequence or codosing the electrons with the oxygen reactant. The SiO2 EE-ALD films could be grown on conducting silicon wafers or insulating SiO2 films. SiO2 EE-ALD is believed to be possible on insulating SiO2 films because the secondary electron yield for SiO2 at electron energies of ∼100–300 eV is greater than unity. Under these conditions, the SiO2 film charges positive during electron exposure and then pulls back secondary electrons to maintain charge neutrality. The SiO2 EE-ALD films had properties that were comparable with thermal SiO2 oxides. The refractive indices of the SiO2 EE-ALD films were similar at n = 1.44 ± 0.02 for various process conditions and equivalent to the refractive index of a wet thermal SiO2 oxide film. In addition, all the SiO2 EE-ALD films yielded etch rates in dilute buffered oxide etch solution that were only slightly higher than the etch rate of a thermal SiO2 oxide film. SiO2 EE-ALD should be useful to deposit high-quality SiO2 films for various applications at low temperatures.

Long-Acting Real-Time Microscopic Monitoring Inside the Proton Exchange Membrane Water Electrolyzer

The proton exchange membrane water electrolyzer (PEMWE) requires a high operating voltage for hydrogen production to accelerate the decomposition of hydrogen molecules so that the PEMWE ages or fails. According to the prior findings of this R&D team, temperature and voltage can influence the performance or aging of PEMWE. As the PEMWE ages inside, the nonuniform flow distribution results in large temperature differences, current density drops, and runner plate corrosion. The mechanical stress and thermal stress resulting from pressure distribution nonuniformity will induce the local aging or failure of PEMWE. The authors of this study used gold etchant for etching, and acetone was used for the lift-off part. The wet etching method has the risk of over-etching, and the cost of the etching solution is also higher than that of acetone. Therefore, the authors of this experiment adopted a lift-off process. Using the flexible seven-in-one (voltage, current, temperature, humidity, flow, pressure, oxygen) microsensor developed by our team, after optimized design, fabrication, and reliability testing, it was embedded in PEMWE for 200 h. The results of our accelerated aging test prove that these physical factors affect the aging of PEMWE.

Recovery of Au and Pd from the etching solution of printed circuit boards by cementation, solvent extraction, reduction, and precipitation

Printed circuit boards (PCBs) contain precious metals like Au and Pd. Therefore, it is important to recover these metals from waste PCBs. A process was developed in this work to recover pure Au powders and Pd compounds from the aqua regia etching solution of waste PCBs. Au(III) and Pd(II) were separated by cementation with Cu powder from the etching solutions containing Al(III), Cu(II), Fe(III), Na(I), Ni(II), Sn(II) and Zn(II). The Au and Pd metals present in the cemented Cu were dissolved together with Cu by the mixture of HCl and NaClO. Au(III) was separated from the leaching solution of the cemented Cu by solvent extraction with Cyanex 272. Then pure Au powders were recovered from the thiourea stripping solution by chemical reduction with hydrazine. In order to recover Pd(II) from the raffinate after extraction of Au(III), Pd(II) was oxidized to Pd(IV) by adding NaClO3 and then pure Pd compound ((NH4)2PdCl6) was recovered by precipitation with NH4Cl. Optimum conditions of these steps were obtained at room temperature. The purity of the recovered Au and Pd compound was higher than 99%.

P‐40: TFT‐LCD a‐Si Wet Etch Technology

In this paper, we investigate a technology to change the method and principle of n+ a‐Si:H etching from conventional dry etch to the innovative wet etch in TFT LCD fabrication. The technology is based on the development of a new wet metal etching solution and the design of the thinnest film thickness of a‐Si:H in the industry, combined with the etching process development, to achieve the etching of two different film layers of metal and N+ a‐Si:H in the back channel of TFT switches in one‐ step(Abbreviated as NW process). The process can effectively improve the capacity of Dry Etch process (Skip N+ Dry Etch); improve the uniformity of back channel a‐Si:H Remain (16.3%‐ >7.6% ); improve product characteristics (Dark I on（ TFT working current） 5.5‐>6.0); improve yield (Yield rate↑0.3%).The process has been successfully developed for the first time in Wuhan BOE and has been widely used for batch products, meanwhile, the process has been extended to Hefei BOE and Fuzhou BOE, and other BOE line sites are also actively exploring the experiment.

Mo2C MXene Nanosheets Made in Different Etching Solutions as Co-catalysts for Hydrogen Production

Mo2C MXene is a two-dimensional material, which can be applied as a co-catalyst to significantly enhance the photocatalytic performance of CdS for H2 production. To understand the effect of the synthesis process of Mo2C MXene nanosheets on the catalytic performance, in this paper, Mo2C MXene was made from Mo2Ga2C by hydrothermal etching in different etchants. Diverse cations (Li+, Na+, K+, or NH4+) in etchants resided on the surface of Mo2C MXene nanosheets. Then, the samples were used to construct CdS/Mo2C-MXene composites for photocatalytic H2 evolution. Among them, Mo2C MXene with Li+ shows the best photocatalytic H2 production rate of 22,048 μmol g–1 h–1 under visible light. The remarkable performance arises from the modification at the nanoscale of Mo2C MXene with Li+, thereby resulting in better photoabsorption behavior, high separation efficiency of photogenerated carriers, and fast charge transfer at the heterointerface. Moreover, the energy band structures explain that the changes of band gap and the position of the conductive band in the photocatalyst tuned by cations are also key to affect photocatalytic activities.

Hierarchical Cu Nanoarray/NiFe Hydroxide Nanostructures for Efficient Electrochemical Water Oxidation

Three-dimensional (3D) hierarchical nanostructures have shown great promise for electrocatalysis, while a conductive core is paramount to boost the ultimate catalytic activity. In the present study, hierarchical NiFe hydroxide–Cu arrays are prepared through solution etch and sequential electrolysis as the electrocatalysts for oxygen evolution reaction (OER). The electrochemically reduced Cu nanoarrays as the core provide superior conductivity for electron transfer, while the unique hierarchical 3D structure provides a large active surface area, a short ion diffusion path, and open channels for efficient gas release. The resulting NiFe hydroxide–Cu arrays on copper foam (CF) exhibit outstanding catalytic performance of 245 and 300 mV, respectively, to achieve current densities of 10 and 100 mA cm–2 in a 1 M KOH solution. A small Tafel slope of 51 mV dec–1 and superior electrochemical durability of up to 100 h are also demonstrated.

INFLUENCE OF TECHNOLOGICAL FACTORS ON THE PHYSICO-CHEMICAL AND OPERATIONAL CHARACTERISTICS OF PRODUCTS BASED ON BASALT FIBERS

The article examines the results of the research work carried out at the TBKV department of the Kyiv National University of Construction and Architecture on the creation of samples of thermal and sound insulation products with increased operational properties based on modified basalt fiber. The topicality of the topic is due to the predicted reduction of the world reserves of energy carriers with a simultaneous increase in the volume of consumption and cost, which determined the tendency to increase the requirements for thermal protection of buildings and structures and the energy efficiency of technological processes. Based on this, the priority direction of scientific research is the development of materials and technologies for the production of highly efficient heat and sound insulation products based on environmentally friendly mineral raw materials. One of the representatives of these materials is basalts and their structural analogues (gabbro, syenites) with obtaining various materials when using them as raw materials.Samples of erupted rocks - basalts and their structural analogues - were selected for research. The breeds of deposits of Ukraine: Yanova Dolyna, Usachkivske, Donetske were used directly in the research.To increase the reliability of the results of the experiment and to observe the logical sequence of the tasks, the research was divided into three stages: technological, modification of basalt fiber and production of flexible heat and sound insulation products [1].The question was considered step by step:- production of low-temperature basalt melt with an extended range of working viscosity;- influence of physical, mechanical and rheological properties of basalt melt;- the process of interaction of basalt fiber with an etching solution in order to adjust the chemical composition in the direction of obtaining the maximum content of silica, aluminum, titanium;- determination of the structural characteristics of the modified basalt fiber after thermal stabilization;- the study of sound insulation characteristics was determined by the change in the nature of the distribution of sound energy during its passage through the thickness of the material.The conducted studies allow us to make a transition to the technological parameters of obtaining TKIV. The technology for the production of flexible thermal and sound insulation products based on modified basalt fiber and the study of their operational characteristics was developed.

Metal-Assisted Etching of n-Type and p-Type Silicon Using Patterned Platinum Films: Spatial Distribution of Mesoporous Layer and Open Circuit Potential of Silicon

Platinum (Pt) is one of the interesting catalysts in metal-assisted etching (metal-assisted chemical etching) of silicon (Si). The Pt-assisted etching induces not only the dissolution of Si under the Pt catalysts but also the formation of mesoporous layer on the Si surface away from them. In this work, we etched n-Si and p-Si by using patterned Pt films with a diameter of 5 μm and an interval of 50 μm. For both the cases, the Si surface under the Pt catalysts was selectively etched and macropores with a diameter of 5 μm were formed. The macropores formed on n-Si were deeper than those formed on p-Si. The mesoporous layer was observed only around the macropores on n-Si, while it was observed over the entire surface of p-Si. We also measured the open circuit potential of Si in the etching solution. The positive shift of potential of n-Si by the Pt deposition was smaller than that of p-Si except for the initial stage of etching, which can be explained by the polarization characteristics. We discussed the etching behavior of n-Si and p-Si on the basis of the results of structure observation and electrochemical measurements.

Development of structural colored TiO2 thin films by varied etching solutions

Currently, one of the most important problems is water scarcity due to increasing population and environmental factors. Humankind can overcome this problem by recycling polluted water. The structural colors obtained from photonic crystal structures draw attention with fadeless bright color, combined with low toxicity and eco-friendliness. In this study, different etching/anodizing processes were applied to obtain Fabry-Perot and Photonic Crystal Ti-TiO2 structures. Structural colors owing to the morphology of the anatase phase on the surface of the samples etched with hydrochloric, sulfuric, and hydrofluoric acid-based solutions were obtained. The structural color of the formation on the titanium surfaces is related to the Fabry-Perot structures, while variations were correlated with Photonic Crystal surface morphologies. Because the high reflectance values contributed to the structural color formation, the photocatalytic efficiency of the samples etched with acid-based solutions was found to be lower than the samples etched with basic sodium and potassium hydroxide solutions. High-efficiency structural color reactors can be obtained by shifting the reflected wavelength range from the absorption wavelength range of the pollution material.

Anisotropic Analysis of Etch Rates for Sapphire Based on a Layer-by-Layer Removal Model of Surface Atoms

In this paper, a layer-by-layer removal model of surface atoms (Al) is established according to the atomic structure of sapphire, which can accurately calculate etch rates of crystal planes and analyze the anisotropy of etch rates of sapphire. Firstly, etch rate distributions of sapphire are gained through different etching experiments of sapphire hemispheres, and the effect of concentrations of the etching solution on etch rate distributions are analyzed. Then, different types of surface atoms are classified based on the types of chemical bonds of surface atoms, the arrangement laws of surface atoms of different crystal planes are analyzed and a general formula for calculating etch rates of different planes is proposed. Finally, the effectiveness of the layer-by-layer removal model of surface atoms (Al) is proved by small errors between calculated rates of the model and experimental rates at different concentrations, and the factors affecting the anisotropy of etch rates of sapphire are summarized, which include: (1) the vertical distances between two adjacent layers of surface atoms of crystal planes; (2) the configurations of the types of surface atoms of crystal planes.

Detection of limited-energy α particles using CR-39 in laser-induced p −11B reaction

Due to the harsh radiation environment produced by strong laser plasma, most of the detectors based on semiconductors cannot perform well. So, it is important to develop new detecting techniques with higher detection thresholds and highly charged particle resolution for investigating nuclear fusion reactions in laser-plasma environments. The Columbia Resin No. 39 (CR-39) detector is mainly sensitive to ions and insensitive to the backgrounds, such as electrons and photons. The detector has been widely used to detect charged particles in laser-plasma environments. In this work, we used a potassium–ethanol–water (PEW) etching solution to reduce the proton sensitivity of CR-39, by raising the detection threshold for the research of laser-induced 11B(p, α)2α reaction. We calibrated the 3–5 MeV α particles in an etching condition of 60°C PEW-25 solution (17% KOH + 25%C2H5OH + 58%H2O) and compared them with the manufacturer’s recommended etching conditions of 6.25 N NaOH aqueous solution at 98°C in our laser-induced nuclear reaction experiment. The results indicate, with the PEW-25 solution, that CR-39 is more suitable to distinguish α tracks from the proton background in our experiment. We also present a method to estimate the minimum detection range of α energy on specific etching conditions in our experiment.

Selective functionalization of silicon nitride with a water-soluble etch-resistant polymer

In semiconductor device manufacturing, it is typically necessary to process devices incorporating both Si3N4 and SiO2 with etching solutions. However, several commercially ubiquitous etchants affect both these dielectrics simultaneously; therefore, high-cost protection solutions or highly selective etchants are required to mitigate this issue. To address this problem, this study examined a simple method of selectively functionalizing Si3N4 with a protective polymer film, thus reducing its etching rate relative to that of SiO2. Several polymers were screened for their selectivity and resistance to buffered hydrofluoric acid (BHF) etching. A water-soluble cellulose-based polymer, DC01, was subsequently found to reduce the etching of Si3N4 selectively, owing to strong interactions between the polymer and underlying bulk material once the native oxide is removed. In addition, X-ray photoelectron spectroscopy results confirmed the retention of DC01 on this substrate after etching, while quartz crystal microbalance measurements indicated the stability of the polymer film after multiple rounds of rinsing with aqueous surfactant solutions. Thus, this polymer has considerable potential as an additive for the simplification of Si3N4/SiO2 composite processing.

Construction of a multi-scale microporous structure in EVA matrix toward passive cooling roofs

Global warming has brought tremendous attention to developing passive cooling materials. Due to the high performance of solar reflection, heat insulation and infrared radiation, constructing porous structures in polymeric matrix has emerged as a promising technique to fabricate passive cooling materials. This work herein demonstrated a multi-scale microporous structure in ethylene-vinyl acetate copolymer (EVA) matrix via chemical foaming and chemical etching. It was found that pore size and shape depended upon the addition and removal of inorganic particles CaCO3. In chemical foaming system, by reflecting 76.9% NIR light and transmitting heat through the atmosphere in the long-wave infrared, the cellular EVA/CaCO3 composites (40% porosity, 13.84 μm avg. pore size)-covered device exhibited a final temperature of 31.6 °C after solar simulation for 1 h with the intensity of ∼594 W/m2. To further enhance the cooling effect, the CaCO3 particles in cellular EVA/CaCO3 composites were removed via 20% HCl solution etching to minimize the pore structure. Higher heat insulation with thermal conductivity of 0.148 Wm−1K−1 accompanied by 65.5% NIR irradiance and 0.84 thermal emittance made the excellent cooling property with a final temperature of 30.6 °C (lower than all EVA/CaCO3 composites-covered device) realize after chemical etching. Furthermore, the prepared porous EVA materials possessed good tensile properties and are of potential value in the field of passively cooled roofs.

Deep multilevel wet etching of fused silica glass microstructures in BOE solution

Fused silica glass is a material of choice for micromechanical, microfluidic, and optical devices due to its chemical resistance, optical, electrical, and mechanical performance. Wet etching is the key method for fabricating of such microdevices. Protective mask integrity is a big challenge due extremely aggressive properties of etching solution. Here, we propose multilevel microstructures fabrication route based on fused silica deep etching through a stepped mask. First, we provide an analysis of a fused silica dissolution mechanism in buffered oxide etching (BOE) solution and calculate the main fluoride fractions like {HF}_{2}^{-}, {F}^{-}, {(HF)}_{2} as a function of pH and NH4F:HF ratio. Then, we experimentally investigate the influence of BOE composition (1:1–14:1) on the mask resistance, etch rate and profile isotropy during deep etching through a metal/photoresist mask. Finally, we demonstrate a high-quality multilevel over-200 μm etching process with the rate up to 3 μm/min, which could be of a great interest for advanced microdevices with flexure suspensions, inertial masses, microchannels, and through-wafer holes.

Chemical etching of InP assisted by graphene oxide

Chemical etching of semiconductor surfaces assisted by various types of carbon-based materials is drawing much attention for the fabrication of those micro-nano structures. We herein demonstrated to apply graphene oxide (GO), a 2D nano-carbon material, as a catalyst for the InP etching reaction, and a possible mechanism of GO-assisted InP etching was suggested by combining XPS analyses. The solubility of the InP oxide layer towards the etching solution affected the rate-determining step of InP etching reaction. When the oxidant reduction reaction catalyzed by GO was the rate-determining step, the etching reaction under GO was enhanced. Furthermore, the etching behavior was different in utilizing different oxidants, which means that the catalytic activity of GO for the oxidant reduction also affects the etching behavior.

Optimization and evaluation of a three-step pretreatment process for PCB microdrills

The traditional Murakami two-step and three-step acid pretreatment processes were introduced to reduce the negative impact of Co on the cemented carbide tools during deposition of the diamond coatings. However, treatment methods requiring a longer etching time and a higher etching solution concentration lead to the formation of pores and cavities on the surface of the substrate, which would damage the substrate and thus significantly decrease the fracture load of the tools, especially microdrills with a small edge diameter. In this study, the pretreatment process of microdrills is optimized based on the traditional three-step process. The surface morphologies and Co content of the microdrills after pretreatment are investigated via scanning electron microscopy and energy-dispersive spectroscopy. The effect of the pretreatment on the fracture toughness of the microdrills and the adhesion of the diamond coatings is evaluated. The results show that the surface microstructure and fracture load of the microdrills are inevitably damaged during the acid and Murakami etching processes. Furthermore, the adhesion of the diamond coating depends on the final step of the acid etching process. The optimized three-step process consists of first etching with an acid solution for 10 s, then etching with a Murakami solution for 4 min, and finally etching with the acid solution for 30 s. This process improves the pretreatment efficiency and coating adhesion without significantly reducing the fracture load of the microdrills.

Biocompatible and Oxidation-Resistant Ti3 C2 Tx MXene with Halogen-Free Surface Terminations.

Surface chemistry influences not only physicochemical properties but also safety and applications of MXene nanomaterials. Fluorinated Ti3 C2 Tx MXene, synthesized using conventional HF-based etchants, raises concerns regarding harmful effects on electronics and toxicity to living organisms. In this study, well-delaminated halogen-free Ti3 C2 Tx flakes are synthesized using NaOH-based etching solution. The transversal surface plasmon mode of halogen-free Ti3 C2 Tx MXene (833nm) confirmed red-shift compared to conventional Ti3 C2 Tx (752nm), and the halogen-free Ti3 C2 Tx MXene has a different density of state by the high proportion of -O and -OH terminations. The synthesized halogen-free Ti3 C2 Tx exhibits a lower water contact angle (34.5°) and work function (3.6eV) than those of fluorinated Ti3 C2 Tx (49.8° and 4.14eV, respectively). The synthesized halogen-free Ti3 C2 Tx exhibits high biocompatibility with the living cells, as evidenced by no noticeable cytotoxicity, even at very high concentrations (2000µgmL⁻1 ), at which fluorinated Ti3 C2 Tx caused ≈50% reduction in cell viability upon its oxidation. Additionally, the oxidation stability of halogen-free Ti3 C2 Tx is enhanced unexpectedly, which cumulatively provides a good rationale for pursuing the halogen-free routes for synthesizing MXene materials for their uses in biomedical and therapeutic applications.