Electrolytic Etching Research Articles

Maryland Bridges: A Conservative Approach to Aesthetic Tooth Replacement – A Case Report

Restoring missing central incisors in the mandibular jaw is a challenging esthetic challenge in dentistry, especially for younger patients. Maryland bridges are a highly effective treatment option, restoring oral function and aesthetics, and resulting in high patient satisfaction. These bridges have advantages over conventional fixed dental prosthesis, such as minimal removal of the tooth structure, minimal pulpal trauma risk, and reduced time and cost. Provisional restorations are usually not required. Maryland bridges are cemented to the abutment tooth using electrolytic etching to retain the metal framework. The bond is strengthened after etching, and the development of resin cements has enhanced bridge retention. A missing anterior tooth poses an esthetic, functional, and rehabilitative problem, especially for younger patients. Resin bonded bridges are minimally invasive, offering advantages such as minimal removal of the tooth structure, minimal pulpal trauma risk, and reduced time and cost. This case report describes the fabrication technique for a single missing lower anterior tooth, focusing on conservative, economical, and esthetic treatment outcomes.

Physical properties and microstructural corrosion propertiesof Laser-bent 304 Stainless Steel Sheets

Laser treatment by laser bending is a technique of treating sheet metal by thermal residual stresses generated by laser assisted heating without any externally applied mechanical forces. The advantages of laser assisted bending over conventional bending include flexibility of non-contact processing, amenability to materials with diverse shape/geometry, and high precision/productivity. Up to now, most of previous work on laser bending was concentrated on study of bending angles/shapes with laser operating conditions, and modelling of the thermal process, however, no work has been reported on corrosion behavior of the laser-bended components. Since the laser bending is a thermal process, it is believed that the thermal process could not only alter microstructure, but also affect corrosion performances, such as intergranular corrosion, due to possible sensitisation caused by repeating laser scans. The aim of the present work is to investigate corrosion performance of laser-bent 304 austenitic-steel sheet with thicknesses of 2 mm and 1.5 mm, respectively, using a 2 kW CO2 laser. After laser treatment, the laser-bent samples were characterised in terms of microstructural change within bent zones consisting of melt-zone and heat-affected zone, using optical microscopy and scanning electron microscopy (SEM). Hardness profiles were obtained across the bent zones. Corrosion performances of the laser-bent evaluated by means of electrolytic etching in oxalic acid and double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests. Laser bending is a thermal process, it is believed that the thermal process could not only alter microstructure, but also affect corrosion performances, due to possible sensitisation caused by repeating laser scans.

Potential applications for modified Klemmsolutions

Abstract The article describes various modifications of Klemm etching solutions and their applications to different materials. In addition to classic immersion etching, electrolytic etching is also used for the first time, demonstrating the potential of this etching method based on sodium thiosulfate and potassium metabisulfide for other materials.

Less is sometimes more – some examples of the reduction of hazardous substances in metallographic etching

Abstract In metallography, the choice of the right etchant is crucial for visualizing the microstructure. As conventional etching agents generally contain a more or less high proportion of hazardous substances that need to be reduced in the future, examples are given of how this reduction is possible in principle. This reduction in hazardous substances is mainly achieved through microscopy contrasts, dilution of etching solutions and electrolytic etching.

Collaborative experiment of the work group “Sample Preparation” on the subject “Reduction of hazardous substances in metallographic etching using electrolytic etching techniques”

Abstract This article shows how conventional etching methods can be replaced by electrolytic processes, thereby reducing hazardous substances during etching. The joint experiment carried out on this topic by the “Sample Preparation” working group uses various materials to show how hazardous substances can be reduced, but also the existing limitations.

Comparison of electrolytic etching and immersion etching for 304L, 316L and 347 austenitic stainless-steel grades

Comparison of electrolytic etching and immersion etching for 304L, 316L and 347 austenitic stainless-steel grades

Influence of electrolytic plasma spatial distribution on nanoporous structure etching on 4H-SiC surface

Single-crystal SiC nanoporous structure has important applications in the field of micro electromechanical systems, chemical sensors and biomedical devices. However, SiC exhibits a strong chemical inertness due to the short interatomic distance and high binding energy, making it significantly challenging to fabricate nanoporous structure. Electrolytic plasma-assisted chemical etching (EPACE) based on electrochemical anodic oxidation and high-activity electrolytic plasma etching is an ideal method for SiC nanoporous structure etching. In which, the spatial distribution of electrolytic plasma has an important impact on EPACE performance, such as etching efficiency and stability. In order to analyze the impact mechanism, this paper studies EPACE in tool electrode mounting posture of vertical and horizontal types by visual observation, real-time recording of voltage-current waveforms during processing, and the morphology analysis of SiC nanoporous structure after etching. It can be found that in the vertical etching type, EPACE can proceed stably because the workpiece immersion depth is greater than the bubble accumulation thickness. However, in the horizontal etching type, bubbles accumulate seriously between the workpiece and the liquid surface, which may cause bubble cavitation and abnormal discharge, leading to damage to the etching surface. The etching current in the vertical etching type is about 1.3 times that of the horizontal etching type, indicating that the bubble mass transfer in the vertical etching type is faster and the etching impedance is smaller, which is beneficial to improve the etching efficiency and obtain a uniform nanoporous structure. Finally, a SiC nanoporous layer with a thickness of 10.6 μm was prepared at etching time t = 50 min in vertical etching type, and the etching efficiency was 212 nm/min. In addition, the prepared nanoporous structure (nanofiber) was connected to the SiC substrate, indicating that it has a good bonding strength.

Effect of Ta addition on primary MC carbide in Ti-Nb-Mo-W-alloyed superalloy

The effect of Ta addition on characterization of primary MC carbides with regard to their morphology, composition, and size in Ti-Nb-Mo-W-alloyed Ni-based superalloy were investigated. Several tools including automated scanning electron microscopy as well as electrolytic etching technology were used for broad characterization of carbides including three-dimensional morphology. The addition of Ta significantly influences the composition and morphology of primary MC carbides. Large dendrite (Ti,Nb,W,Mo)C carbides were changed to smaller (Ta,Ti,Nb)C carbides. The hardness of both MC primary carbides and the matrix were increased. MC carbides in the studied superalloys were developed dendrite in three-dimensional morphology, which was much larger than that in two-dimensional morphology. The formation mechanism of carbides was clarified by thermodynamic calculation.

Influence of Deep Etching Surface Treatment to The Tensile Strength and Microstructure of Brazing Aluminium - Mild Steel

Since hard metals are among the materials that liquid brazing alloys scarcely adhere to, they should not be brazed without first removing the surface layer after sintering. The electrolytic etching method, which gives the surfaces of materials that are hardly wettable very good energetic qualities, is given specific attention. Deep etching is done by using a high concentration of acid solution to roughen the surface. Both dry and wet settings are suitable for etching. An etching fluid is used for etching in a wet environment. Typically, the plate or metal is submerged in an etching solution, where the substance is chemically broken down. While in dry etching, the plasma’s gas phase is where the etching takes place. Due to the presence of plasma in this situation, the etching process that takes place combines chemical and physical processes. Plasma etching is another name for dry etching. Deep etching is an etching process to obtain a rougher surface. Wet deep etching requires a longer immersion time and even several immersions are required. The purpose of this study was to determine the effect of etching treatment in the brazing process of Aluminium-Mild steel for its microstructure and mechanical properties. The specimens in this study used aluminium 6000 series, mild steel, Alusol ER4043, and etching fluid. Mild steel surfaces are deep etched before brazing. Specimen manufacturing standard refers to ASTM D1002. A micro photo test was conducted to compare the surface conditions of aluminium and mild steel with and without etching treatment. The deep etching process is carried out in three variations of time, namely 20, 30, and 40 minutes. The results showed that the tensile strength increased with deep etching treatment on the surface.

Electrochemical etching of n-type GaN in different electrolytes

Nanosized pores were introduced into GaN epitaxial films via electrochemical (EC) etching in strong electrolytes including NaOH, HNO3, NaNO3, and NaCl. The growth behaviors of GaN nanopores show a strong correlation with the electrolyte types under the same applied bias and electrolyte concentration. Specifically, the resulting morphologies (e.g. pore growth direction and pore size) were mainly pertinent to the anions instead of cations. Pore sizes as small as a few nanometers and pore directions between the horizontal and vertical directions can be adjusted by selecting the electrolytes and etching voltages. The depletion model was employed to interpret the carrier flow pathways, and the pore propagation direction can be regarded as the sum of etch rate vectors of intended etching direction and preferential oxidation direction. Finally, the near-infrared nanoporous (NP) GaN distributed Bragg reflectors (DBRs) were manufactured by the EC etching in different electrolytes. Our study points out that the type of anions in electrolyte greatly impacts pore morphologies of EC etched GaN:Si, thereby affecting the future applications.

Morphology and Distribution of Primary Carbides in Forged Cr-Ni-Mo-V/Nb Steel.

This study aims to investigate in situ the three-dimensional (3D) morphology and distribution of primary carbides (PCs) in electro-slag remelting (ESR) forged 30Cr3Ni3Mo2V steel. A facile non-aqueous electrolytic etching method was applied to prepare 3D PCs on the matrix. The morphology, composition, and element concentrations of PCs were characterized using a combination of optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and electron back-scattered diffusion (EBSD). The precipitation, type, and composition of PCs in the same steel were also simulated using Thermo-Calc software Version 2015a. The results indicate that PC is rich in Nb, which is a potential heterogeneous nucleating agent. Both the size and number of PCs increase from the edge to the center of the ingot. The large-sized PCs present three dominant types of morphology, which vary in different regions, i.e., a bulky type dominates in the edge region, a lamellar type dominates in the middle region, and a stripy type dominates in the core region. The results of EBSD analysis show that the orientation of PCs with different morphologies is different and that more nanosized V-rich type carbides are precipitated on the matrix. The thermodynamic calculations show that MC precipitates from the liquid phase when the solid phase fraction is greater than 0.985 and that the MC-type carbides are rich in Nb, which agrees well with the experimental results.

Analysis of Biocompatible Metallic Materials used in Medicine

The paper presents the results of the analysis of two biocompatible materials, Kirschner wires of different thicknesses. Kirschner wires (K-wires) are stainless steel pins used in surgery to fix bone fragments and to provide an anchor for skeletal traction. The K-wires are produced in different diameters. In the present work, a scanning electron microscopy and light microscopy were employed to document the microstructure of two K-wires with different thicknesses. Before observation, the wires were prepared by a standard metallographic procedure (grinding and polishing) followed by electrolytic etching. The chemical composition was determined by studying the wires using quantitative energy-dispersive X-ray spectrometry. It has been found that the chemical composition of the materials corresponds to Cr-Ni stainless steel. In the thick Kirschner wire (sample no. 1) a deformed microstructure after drawing was observed. Sample no. 2 (thin Kirschner wire), on the other hand, consisted of polyhedral austenitic grains, which were formed after recrystallization annealing. Furthermore, isolated microparticles were observed and assigned to titanium nitride. A Vickers hardness test was also performed on the samples. It has been found that the hardness of sample no. 1 was 428.8 HV 0.5. The average hardness of sample no. 2 was 213.4 HV 0.5. It can be concluded that recrystallization annealing decreases the hardness of the material. The K-wires with smaller diameter are thus easier to bend which facilitates their fixation in human body.

Communication—Controlling Etching of Germanium through Surface Charge Manipulation

Potassium hydroxide (KOH) aqueous solutions can effectively etch germanium. Etch rates were determined in an electrolytic etch cell. Electrically isolated Ge wafers were subject to an etch rate of 1.45 ± 0.07 nm min−1, increasing to 12.6 ± 0.2 nm min−1 when grounded, 97 ± 2 nm min−1 when biased at −0.9 V, and 138 ± 2 nm min−1 with periodic biasing. Results suggest that the previously reported limited etching in KOH is associated with the recombination of holes with electrons injected from the surface reaction. The results of this study demonstrate that changing the hole concentration through biasing is an effective tool to control electrolytic etch rates, enabling future selective etching processes for germanium.

The Performance of Different Etchants on the Carbides of Ni600 and Ni625

Nickel-based alloys that contain chromium are widely used in corrosion-resistant applications in industry, but they are sensitive to the environment when the passive chromium oxide layer is damaged. In Ni600 and Ni625 alloys, precipitates can deplete the surface layer of chromium oxide. To better characterize and analyze the nickel alloy surfaces and their chromium carbides, chemical etching with different etchants and electrolytic etching were applied to sample surfaces. This paper revealed their efficacy in etching various carbides within the nickel alloys, and orange phases ranging from 2 to 20 μm in optical micrographs were identified as titanium-containing compounds. Carbides located on the grain boundaries were determined to be Cr23C6 and were surrounded by chromium-depleted zones. The findings and figures in this paper provide a more intuitive reference for future analysis of carbides and titanium nitrides, enhancing the understanding of their impact on the corrosion resistance of these alloys, which will not only contribute to the material science field but also aid in developing the Ni-based alloys for industrial applications.

Titanium Blade with Jagged Micro-scale Structure Fabricated via Electrolytic Etching

Titanium Blade with Jagged Micro-scale Structure Fabricated via Electrolytic Etching

Texturing skin-pass rolls by high-speed laser melt injection, laser ablation, and electrolytic etching

Skin-pass rolls are used for setting the final sheet thickness and surface texture. For sheet metal that is produced for forming, textured skin-pass rolls featuring a high-low structure are used in order to improve the formability and paint adhesion of the sheet. In this paper, new textures for skin-pass rolls generated by high-speed laser melt injection (HSLMI) are presented and characterized. Furthermore, it is studied how the texture of the roll is transferred to steel and aluminum sheets. With HSLMI, metal matrix composite (MMC) layers featuring spherical fused tungsten carbide (SFTC) particles with a high hardness could be produced on skin-pass rolls. For generating an increased high-low structure, laser ablation and electrolytic etching were carried out after HSLMI and grinding of the rolls. An analysis of the topography showed that different protruding heights between SFTC particles and matrix can be set. The textures generated by laser ablation showed a topography featuring two homogeneous height levels, whereas a texture with spherically shaped particles could be generated by electrolytic etching. Furthermore, it was found that all textures were transferred from the roll to both steel and aluminum sheets. The transfer of the textures mainly depended on the protruding height of the SFTC particles and the SFTC particle content of the roll.

Study of the influence of the mode of rotation of pipe in the cold rolling process on the microstructure, mechanical properties and accuracy

Goal. Obtaining experimental results on the influence of the turning mode during cold rolling on the microstructure, mechanical properties and accuracy of the geometry of the pipes to improve their quality. Method. Experiments were carried out on equipment used in production and having appropriate inspections. We used a grinding machine, a device for electrolytic etching, a MIM 7 microscope, and a press for stretching samples. The accuracy of the geometric dimensions was determined using tube micrometers. Rolling route 25×2.5 mm → 16×1.5 mm. Steel 08Х18Н10Т. The results. Two rotation modes were performed: mode 1 – feed 2, 3, 4, 5 mm in front of the straight one, and the rotation before the reverse movement of the cage; mode 2 – feed 2, 3, 4, 5 mm in front of the straight, and turn in front of the straight and reverse movement of the cage.For mode 2, in comparison with mode 1, the grain size near the inner surface of the pipes is visually smaller than near the outer surface.The strength limit, yield strength and relative elongation for modes 1 and 2 were found to be close in value.With regard to the accuracy of the geometry of the pipes, it was determined that in mode 2 compared to mode 1: – the transverse thickness of the pipes decreases by 1.4–1.6 times; – the ovality of the pipes is reduced by 1–2 times (feeds from 2 to 5 mm); – the spread of the diameter along the length of the pipe decreased almost twice. Scientific novelty. For the first time, new experimental industrial data on the influence of the rotation mode on the microstructure were obtained. It is shown that the grain size near the inner surface of the pipes is smaller than near the outer surface.For the first time, obtained experimental industrial data on the effect of the tube rotation mode on the values of strength limit, yield strength and ultimate elongation showed that the rotation mode did not affect their change.Additional experimental dependences on the influence of the pipe rotation mode on the transverse variation, ovality and spread of the outer diameter of the pipes during cold rolling of the pipes were obtained - the reduction of the transverse variation was 1.4–1.6 times, ovality 1–2 times, and the diameter variation was almost 2 times. Practical significance. The obtained results are needed in the development of technologies for the production of pipes with increased quality requirements (microstructure, heterogeneity, ovality, diameter dispersion).

Electrolytic Etching of Germanium Substrates with Hydrogen Peroxide

Anodic electrolytic etching of germanium has been performed in hydrogen peroxide etchants with controlled external conditions. In-situ current and ex-situ etch-depths were measured and tracked with respect to etchant composition and stir rates. Gas bubbles formed during the etching process were found to cause non-uniformity in etch-current and surface quality. The effects were minimized in specific composition spaces. Quantitative analysis revealed a linear correlation of the number of electrons transferred during germanium oxidation with the number of surface atoms removed. Experimental results of 2.77 electrons/atom deviate significantly from 4 electrons/atom previously reported for silicon. The conclusion is that etching mechanisms for germanium are sufficiently different from those for silicon which invalidates the direct transfer of processing techniques between the two materials.

Multifunctional Na2TiO3 Coating-Enabled High-Voltage and Capacitive-like Sodium-Ion Storage of Na0.44MnO2.

Sodium-ion batteries, as an attractive option for large-scale energy storage, still face the problems of low energy density and unsatisfactory rate performance. Among various cathodes, the tunnel-type Na0.44MnO2 with large S-shaped Na+ transport tunnels is one of the promising cathode materials for fast and robust sodium-ion storage, yet suffering from Mn dissolution and structural collapse. Herein, a Na-rich layered oxide Na2TiO3 is first constructed as a multifunctional coating layer on the surface of the Na0.44MnO2 nanorod. Na2TiO3 not only acts as an Na+ reservoir, but also serves as a protective layer to prevent Na0.44MnO2 from electrolyte etching. Besides, the derived Ti-doped Na0.44MnO2 transition layer supplies additional Na+ diffusion pathways along the radial direction of the nanorod with a short migration distance. The optimized 3 wt % Na2TiO3-coated Na0.44MnO2 exhibits enhanced an initial capacity of 127 mAh g-1 at 2-4.5 V. In addition, it shows an ultra-high capacitive-like capacity ratio of 96.7%, hence delivering an excellent rate performance of 80.2 mAh g-1 at 20C. Long-term cycling tests indicate splendid stability against high voltage, achieving 97.7% capacity retention at 20C after 900 cycles. This work provides an effective strategy to improve the rate performance and high-voltage stability of Na0.44MnO2 for high energy and power density batteries.

MORPHOLOGY AND PHASE COMPOSITION OF DIFFUSION BORIDE LAYER BASED ON METALLOGRAPHIC ANALYSIS OF STEEL 45

Chemical-thermal treatment in general and borating in particular are highly effective ways to increase the service life of working bodies and machine parts, as well as tools. At the same time, it is necessary to select possible grades of steels, which are preferably subjected to boriding, depending on the goal. To solve practical problems in order to control the quality of a boride diffusion coating, there is a need to determine the strength and morphological characteristics of the boride layer and its phase composition. Since the high- boride FeB phase has low performance characteristics (high brittleness, creates tensile stresses on the surface, leading to cracking and spalling in the boride layer), in most cases the content of the FeB phase in the coating is limited to an upper limit of no more than 10–15 % of the thickness of the boride layer. Determination of the phase composition of boride layers is preferably carried out by electron microscopy methods, however, under production conditions, this is a laborious task. One of the options for analyzing the structure and morphology of the results obtained is the visualization of the phase composition of boride diffusion layers using "color etching'' with the possibility of assessing the structural-phase state using optical microscopy. It is shown that the electrolytic etching method proposed in this work in a saturated aqueous solution of alkaline sodium picrate makes it possible to obtain high-contrast images of the microstructure of the boride layer, which can subsequently be automatically processed in modern software systems for metallographic analysis in order to qualitative and quantitative assessment of the structural-phase state. Compared to the chemical methods of "color etching", the electrochemical etching method does not require highly skilled personnel and can be used in a production laboratory.