Acid Etching Time Research Articles

Superhydrophobic Surfaces on 5052 Aluminum Alloy Obtained from LDH Film Modified with Stearic Acid for Enhanced Corrosion Protection

This paper aimed to develop and characterize superhydrophobic surfaces with anticorrosive properties obtained by the chemical modification of the 5052 aluminum alloy with variation of acid etching time, formation of lamellar double hydroxides (LDH) film and immersion in stearic acid. The specimens were etched in HCl (2M) at 5, 10 and 30 min. The aluminum plates were treated with aqueous solution of zinc nitrate (0.1 M) in the presence of ammonia and then immersed in a stearic acid and ethanol solution (1% w/w) to reduce surface energy. Contact angles (CA) were determined. Surface morphology and composition were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersion spectroscopy (EDS), respectively. Linear polarization tests were performed to analyze corrosion resistance. The optimal superhydrophobic performance was obtained with a contact angle of 154º for 30 min of acid etching. This condition also showed higher corrosion resistance, obtaining higher values of Ecorr and lower values of corrosion current density.

Process optimization of selective wet etching for fabrication of high-aspect-ratio and uniform multilayer grating reference materials

Background: The multilayer gratings are considered as the potential length-standard-traceable lateral scales for calibrating the next-generation critical dimension scanning electron microscope (CD-SEM) magnification. As a key step in the fabrication of multilayer gratings, selective wet etching determines the final grating structure formation. However, the effects of the etching process parameters on the multilayer gratings in several nanometer scales have not been reported in detail. Aim: By optimizing the process of selective wet etching, we should fabricate high-aspect-ratio and uniform multilayer gratings to obtain high-contrast secondary electron signals and stable secondary electron images while also obtaining measurement accuracy from the small line edge roughness. Approach: Based on the analysis of the important factors in the etching process and SEM and TEM measurement results, we evaluate the effects of ultrasonic agitation, HF acid concentration, etch time, and linewidth scale on the aspect-ratio and uniform of multilayer gratings. Results: We recommend to etching the multilayer films with an HF acid concentration of about 2% during the ultrasonic agitation for uniformity. Moreover, selective wet etching reaction is limited by scale when the linewidth is below 20 nm. Despite the fact that the grating structure is fragile and easy to be broken down, for linewidths of about 10 and 5 nm, the aspect ratio of multilayer gratings can reach about 3 and 2, respectively. Conclusions: By focusing on the optimum conditions of ultrasonic agitation, HF acid concentration, and linewidth scale in the selective wet etching, selective wet etching can be used to fabricate high-aspect-ratio and uniform multilayer gratings with linewidth below 20 nm.

A Randomized Double-blind Clinical Trial of Dentin Surface Treatments for Composite Restorations in Noncarious Cervical Lesions: A 36-month Evaluation.

This randomized, double-blind clinical trial aimed to evaluate the influence of different dentin surface treatments in noncarious cervical lesions (NCCLs). Twenty-nine patients participated in this study. One hundred sixty-five NCCLs were selected and randomly assigned to three groups: G0 (control group) with phosphoric acid etching for 15 seconds; G1: phosphoric acid etching for 30 seconds; and G2: ultrasound probe applied for 30 seconds on the dentin surface. Class V composite resin restorations were performed (Z350, 3M ESPE, St Paul, MN, USA). The restorations were evaluated at baseline and at six, 12, 24, and 36 months according to the World Dental Federation criteria. Survival curves were obtained using the Kaplan-Meier method and the log-rank test. Comparisons between groups and times were performed using the McNemar and Chi-square tests (α =0.05). The presence of failures due to retention was statistically different among the groups ( p=0.012), and G0 and G2 showed better clinical performance than did G1. Sensitivity decreased over time in all groups. Marginal discoloration, postoperative sensitivity, and marginal adaptation were not different among the groups ( p>0.05). The studied dentin surface treatments showed similar clinical performance to the conventional technique at 36 months in terms of marginal discoloration, marginal adaptation, and postoperative sensitivity. In contrast, increased acid-etching time resulted in a higher risk of failure due to retention over time in composite Class V restorations.

Effect of reducing acid-etching duration time on compressive strength and bonding of a universal adhesive to calcium silicate cements.

To assess the effect of acid-etching duration time on the compressive strength, microstructure and shear bond strength of All-Bond Universal adhesive to MTA-Angelus (AMTA), and Biodentine (BD). Forty-eight cylindrical specimens (4mm in diameter, 6mm in height) of AMTA in four groups and 48 specimens of BD in four groups (n=12) were prepared and stored for 72h. The control groups were unetched whilst the three experimental groups were acid-etched for 5, 10 and 15s, respectively, followed by compressive strength testing. The effect of the various acid-etching times on surface micromorphology was evaluated under a scanning electron microscope. Similar groups were bonded using All-Bond Universal and Aelite Flo and shear bond strength was tested. Data were analysed using two-way ANOVA and Tukey tests. 10-s and 15-s acid-etching reduced the compressive strength of AMTA and BD (P<0.001), while 5-s etching did not (P≤0.86). In all the groups, BD had greater compressive strength compared to AMTA. Contrary to BD, the three etched AMTA groups had significantly higher shear bond strength compared to the control group (P<0.001), with no significant differences between them. The etched groups of AMTA had shear bond strengths comparable to all the BD groups. Scanning electron microscope observations indicated variable surface morphologies such as remnant crystals and cracking/eroding in all our groups of AMTA; though these differences were less prominent for BD. Shortening the acid-etching time to 5s resulted in a beneficial effect in terms of resin bonding for AMTA while preventing the detrimental effect of 10-s and 15-s etching on the compressive strength of AMTA and BD. However, the three etching times had no effect on resin-BD bond.

Obtaining scratch-free specimens of dental enamel prepared by sectioning, grinding, polishing, and acid etching for scanning electron microscopy.

The aim of the present study was to identify the stage during acid etching of dental enamel where scratches introduced by sectioning and grinding procedures were eliminated. Nitric acid was used as etchant. Four hundred 2-3 mm-thick longitudinal sections of human third molar crowns were assigned to 80 groups, each group differing with respect to grinding procedure (silicon carbide paper grit 600; 1,000; 1,200; and 1,200 + polishing), acid concentration (0.1%, 1%, 2.5%, and 5%) and etching time (15, 30, 45, 90, and 180 s). Observation of the specimens with scanning electron microscopy (SEM) showed that elimination of scratches was facilitated by increasing fineness of grinding paper and polishing, and by increasing acid concentration and increasing etching time. An acid concentration of 0.1% did not remove scratches totally irrespective of grinding procedure or etching time, 1% acid removed most scratches after 45-90 s, while 2.5% and 5% acids removed most scratches after 30-45 s. It is proposed that the scratches are eliminated/obscured through a combined effect of the acid and the inherent structure of the enamel. The results of the present study may serve as a guide in choosing the best procedures for obtaining scratch-free enamel surfaces through acid etching with the least possible loss of enamel substance. Research highlights Sectioning and grinding produce scratches in dental enamel. Scratches are eliminated by acid etching prior to SEM studies of enamel structure. Scratch elimination increases with increasing acid strength and etching time and is facilitated by finer grit grinding paper and polishing.

How sensitive are glass-ceramics to acid etching time?

How sensitive are glass-ceramics to acid etching time?

Effect of hydrofluoric acid surface treatments on micro-shear bond strength of CAD/CAM ceramics.

IntroductionDental ceramics are appreciated as highly esthetic restorative materials that can simulate the appearance of natural dentition better than other materials. The aim of this study was to evaluate the effect of hydrofluoric acid concentration and etching time on micro-shear bond strength (μSBS) to IPS e.max CAD and Vita Mark II of a dual cured resin cement (Panavia F2.0).MethodsThis study was an experimental in vitro study, performed in the dental material research center of Babol University of Medical Sciences in 2016. Two hydrofluoric acid concentrations (5% and 10%) and three different etching times (20, 60 and 120 seconds) were used to etch the specimens respectively. A silane coupling agent (Clearfil porcelain activator) and priming and bonding agent (Clearfil SE bond) were used on the etched surfaces in accordance to the manufacturer’s instructions of use. Then resin cement was applied on the prepared ceramic surfaces and light cured. μSBS between resin cement and the porcelains were measured with a universal testing machine. Mode of failure was observed with 40× magnification by means of a Stereo microscope. Data were analyzed with ANOVA and independent-samples t-test and Chi-square tests.ResultsIn both e.max and Vita Mark II groups, μSBS were not significantly different when different etching times (one-way ANOVA) and HF acid concentrations (Independent-samples t-test) were used (p>0.05), but the highest μSBS was shown in e.max specimens etched 60 s with 5% HF and Vita Mark II specimens etched 20 s with 10% HF. μSBS of e.max was significantly higher than Vita Mark II (p=0.00).ConclusionBest surface treatment for e.max and Vita Mark II ceramics is 20 s etch using 5 % hydrofluoric acid.

Effect of Hydrofluoric Acid Concentration and Etching Time on Bond Strength to Lithium Disilicate Glass Ceramic.

The aim of this study was to evaluate the influence of different concentrations of hydrofluoric acid (HF) associated with varied etching times on the microshear bond strength (μSBS) of a resin cement to a lithium disilicate glass ceramic. Two hundred seventy-five ceramic blocks (IPS e.max Press [EMX], Ivoclar Vivadent), measuring 8 mm × 3 mm thickness, were randomly distributed into five groups according to the HF concentrations (n=50): 1%, 2.5%, 5%, 7.5%, and 10%. Further random distribution into subgroups was performed according to the following etching times (n=10): 20, 40, 60, 120, and 20 + 20 seconds. After etching, all blocks were treated with a silane coupling agent followed by a thin layer of an unfilled resin. Three resin cement cylinders (∅=1 mm) were made on each EMX surface, which was then stored in deionized water at 37°C for 24 hours before testing. The μSBS was in a universal testing machine at a crosshead speed of 1 mm/min until failure. Data were submitted to two-way analysis of variance, and multiple comparisons were performed using the Tukey post hoc test (α=0.05). One representative EMX sample was etched according to the description of each subgroup and evaluated using scanning electron microscopy for surface characterization. The HF concentrations of 5%, 7.5%, and 10% provided significantly higher μSBS values than 1% and 2.5% (p<0.05), regardless of the etching times. For 1% and 2.5% HF, the etching times from 40 to 120 seconds increased the μSBS values compared with 20 seconds (p<0.05), but etching periods did not differ within the 5%, 7.5%, and 10% HF groups (p>0.05). The effect of re-etching was more evident for 1% and 2.5% HF (p<0.05). Different HF concentrations/etching times directly influenced the bond strength and surface morphology of EMX.

Aspects of adhesion tests on resin–glass ceramic bonding

ObjectivesThis study aimed to compare and contrast two resin–ceramic bond strength tests, the tensile bond strength and the four-point bending tests. The effects of hydrofluoric acid (HF) etching time and storage condition on bond strength were also studied. MethodsCeramic beams (N=480) with the dimensions of 2.00×2.00×12.45mm3 were sectioned from lithium disilicate ceramic ingots (IPS e.max CAD), then polished and fired for final crystallization. The joint surfaces were etched with HF gel (IPS Ceramic etching gel) for 20s, 40s, or 60s of each group (n=160). Then, a silane coupling agent (Vitasil®) was applied in a single application on the HF etched surfaces, left for 60s before air-drying. Two beams were bonded together with resin composite cement (Variolink II®) in a tailored-mold (2.00×2.00×25.00mm3) to control cement thickness to 0.10mm and then light cured on both sides. The bonded specimens were further divided into two groups (n=40): (1) tested one day after luting (dry); and (2) tested after storage in 37°C distilled water for 4 weeks. Two mechanical tests were used (n=20): the tensile bond strength and four-point bending tests. Bond strength results were subjected to two-way AoV, and Weibull statistics with α=0.05. Fracture surfaces were examined visually and verified using light microscopy. ResultsThe four-point bending test showed a higher consistency than the tensile bond strength test using Weibull statistics (p<0.01). The effect of HF etching time on the flexural strength was significant, with longer HF etching times decreasing the flexural strength (p<0.01). Storage also had a significant effect on the flexural strength (p<0.01). However, HF etching time did not have a significant effect on the tensile bond strengths (p>0.05) and the influence of the storage time was marginally significant (p<0.05). More than 75% of specimens failed adhesively in the four-point bend test while a mixture of adhesive, cohesive and mixed failures was observed in the tensile bond test. SignificanceThe four-point bending test might be a better approach to evaluate bond strengths. Increased HF etching time and a longer storage period resulted in a decrease in the flexural bond strength. However, both HF etching time and storage time had no significant effect on the tensile bond strengths.

The influence of acid etching on the electrochemical supercapacitive properties of Ni[sbnd]P coatings

Amorphous NiP coatings were deposited onto Ti substrates using the electroless method and subsequently etched with nitric acid at different concentrations. Such coatings were employed as a potential electrode for a supercapacitor, with the results indicating that these electrodes exhibited high specific capacitance by controlling the etching conditions, including acid concentration and etching time. Dealloying by acid etching can significantly improve the supercapacitive performance of NiP coatings. The specific capacitance increased 40-fold and achieved levels as high as 865Fg−1 at 10mVs−1 and 1254Fg−1 at 1Ag−1. This is mainly ascribed to the formation of porous structures and thus an increase of surface area due to Ni dissolving in acid solution. According to impedance analysis, the etching step can decrease the charge transfer resistance and Warburg impedance, thus improving the pseudocapacitive property. Moreover, the etched NiP coatings exhibit good cycling performance, and there is no noticeable specific capacitance decrement observed after 500CV cycles at a scan rate of 10mVs−1. Specifically, such electrodes also have low reflectivity, as low as 0.4%.

Using Anodic Aluminum Oxide Film and Nanoimprint to Produce Polymer Anti-counterfeit Labels

An anodic aluminum oxide (AAO) film fabrication process and photolithography were combined to produce a patterned array of nano-hemispheres. This barrier was then used as the substrate on which conductive metals were vapor-deposited to produce electrodes. Nano electroforming was then utilized to deposit nickel on the surface of the array of nano-hemispheres. The oxidized aluminum was etched with phosphoric acid to form a complementary array of nano-pits. Finally, the technique of nanoimprinting was used to transfer the unique structure of the barrier to a polymer. Scanning electron microscopy (SEM) was used to explore the effects of different voltages on the fabrication process and of phosphoric acid etching time on the shape of the barrier. An atomic force microscope (AFM) was used to verify that the nano-array structure of the aluminum oxide film had been completely replicated on the polymer. The regular arrangement of nano-hemispheres refract light and also cause interference, such an array is referred to as a photonic crystal. This type of special structure can be used in counterfeit protection and in many other optical applications.

Electrical Properties of Porous Silicon for N2 Gas Sensor

The application of porous silicon (PSi) for gas sensing devices has gained a considerable attention in the last decade. This work considers the electrical features of PSi layers prepared by electrochemical etching. We find that in order to get a better understanding of the absorption properties of PSi surface, it is necessary to know how the PSi morphology depends on the etching parameters. The physical structure of PSi, i.e., porosity, and pore size distribution can be controlled by changing the Hydrofluoric Acid concentration, current density, anodizing length and etching time in anodizing procedure. We describe our test system for gas sensors and investigate on the electrical behavior of PSi layers (p-type) in N2 gas for various fabrication conditions. The results show that the current density increases significantly as N2 gas is adsorbed. The measurements of the I-V characteristics were carried out at atmospheric pressure, room temperature, and with N2 gas as well.

Quantification of hydrolytic degradation of cured urea-formaldehyde resin adhesives using confocal laser scanning microscopy

This study reports a method of measuring the extent of hydrolytic degradation of cured urea-formaldehyde (UF) resins trapped in the lumen of softwood tracheids, using confocal laser scanning microscopy (CLSM) which enables quantitative determination of the area of a cured UF resin in the lumen as a function of acid etching time. Two formaldehyde/urea (F/U) mole ratios (1.6 and 1.0) and two hardener levels were employed to compare the extent of hydrolytic degradation of cured UF resins. For comparison, we also measured the mass loss of cured UF resin films after acid etching. Cured UF resins with a 1.6F/U mole ratio resulted in greater hydrolytic degradation than those with a 1.0F/U mole ratio. The hardener level also showed a clear influence on the extent of degradation with a limited consistency. These results indicate that cured UF resins with higher F/U mole ratios are more easily hydrolyzed than those with low F/U mole ratios, which could be ascribed to a more branched network structure of cured UF resins with a high F/U mole ratio.

Effect of Hydrofluoric Acid Etching Time on Titanium Topography, Chemistry, Wettability, and Cell Adhesion.

Titanium implant surface etching has proven an effective method to enhance cell attachment. Despite the frequent use of hydrofluoric (HF) acid, many questions remain unresolved, including the optimal etching time and its effect on surface and biological properties. The objective of this study was to investigate the effect of HF acid etching time on Ti topography, surface chemistry, wettability, and cell adhesion. These data are useful to design improved acid treatment and obtain an improved cell response. The surface topography, chemistry, dynamic wetting, and cell adhesiveness of polished Ti surfaces were evaluated after treatment with HF acid solution for 0, 2; 3, 5, 7, or 10 min, revealing a time-dependent effect of HF acid on their topography, chemistry, and wetting. Roughness and wetting increased with longer etching time except at 10 min, when roughness increased but wetness decreased. Skewness became negative after etching and kurtosis tended to 3 with longer etching time. Highest cell adhesion was achieved after 5–7 min of etching time. Wetting and cell adhesion were reduced on the highly rough surfaces obtained after 10-min etching time.

Uninfiltrated Collagen in Hybrid Layers produced after Reduced Acid-etching Time on Primary and Permanent Dentin.

This study evaluated the influence of acid-etching time on collagen exposure in adhesive interfaces established on primary and permanent dentin. Flat dentin surfaces were produced on sound primary molars and premolars (n = 8). The surfaces were divided into mesial and distal halves, and each half was etched with phosphoric acid for 5 or 15 seconds. The teeth were randomly allocated into two groups according to the adhesive system applied: Prime & Bond NT or Prime & Bond 2.1. After the adhesive application, the specimens were processed for Goldner's trichrome staining. The thickness of the uninfiltrated collagen zone (UCZ) in the hybrid layer was measured under optical microscopy. Data were analyzed by analysis of variance and Tukey tests (α = 0.05). The thickness of UCZ was adhesive dependent. Within the same substrate, the specimens treated with Prime & Bond 2.1 presented thicker UCZ when etched for 15 seconds. Collagen exposure was significantly higher for the primary teeth etched for 5 seconds and treated with Prime & Bond 2.1. The thickness of UCZ in hybrid layers is directly affected by acid-etching time and by the adhesive system applied. Primary dentin seems to be more susceptible to collagen exposure than is permanent dentin. Both acid-etching time and adhesive system can influence the amount of exposed collagen interfering on resin-dentin bond quality, especially on primary dentin.

Contact Angle Measurement on Medical Implant Titanium Based Biomaterials

The aim of present research was to study the effect of some surface modification processes on wettability of Ti6Al4V surfaces for medical implants quantified by using the measurement of contact angle. The surface modification procedures of several disc samples were performed by sand blasting, acid etching, passivation, and their combinations. Sand blasting was done with 250...300μm SiO2 large grits. The acid etching process was performed in a dual bath of H2SO4 1n and HCl 1n (1:1) at different elevated temperatures (60°C, 80°C, and 100°C) using different process durations (1h, 3h, 6h, 12h, and 24h). Passivation was done in 30% HNO3 at room temperature. On modified surfaces we evaluated topography, by measuring roughness, and analyzing scanning electron micrographs. Contact angle was measured using static method and direct measurement of the tangent angle at the three-phase contact point on a sessile drop profile. We found that the influence of sand blasting prior to acid etching at low temperature (60°C) on contact angle is beneficial when using long acid etching times (12h and 24h). Increasing the process time for acid etching leads to a decrease in contact angle which is a desired result. Increasing the temperature of acid etching bath leads to an increase in contact angle, thus decreasing the wettability. The passivation treatment leads to an increase of contact angle on sand blasted surfaces, lowering the hydrophilic properties of surfaces, and does not influence significantly the contact angle on surface without sand blasting treatment. The best preparation procedure, in terms of wettability measured by contact angle, was found to be sand blasting, followed by acid etching in above mentioned dual acid bath at 60°C for 24hours. In this case we measured a contact angle of 46° showing good hydrophilic properties.

Effects of Different Acid Etching Times on the Compressive Strength of Three Calcium Silicate-based Endodontic Materials

Effects of Different Acid Etching Times on the Compressive Strength of Three Calcium Silicate-based Endodontic Materials

Efecto de los diferentes tiempos de grabado ácido sobre la resistencia de unión de un sistema adhesivo autoacondicionante en esmalte bovino

Effect of the different acid etching times over the bond strength of a self etching adhesive system in bovine enamel.

Acid concentration and etching time efficacy on lithia-based glass ceramics

Acid concentration and etching time efficacy on lithia-based glass ceramics

Demineralized Dentin as a Semi‐Rigid Barrier for Guiding Periodontal Tissue Regeneration

Guided tissue regeneration (GTR) is an accepted approach in the correction of periodontal bone loss. Nonetheless, the deficiencies of commonly applied absorbable membrane, such as flexibility and limited osteoconductive and osteoinductive capability, still leave much room for improvement. Thus, the feasibility of applying demineralized dentin tissue to improve the therapeutic effect of GTR in periodontal regeneration was explored. Demineralized dentin was harvested after acid treatment, and its physiochemical properties were assessed in terms of mineralization density, contact angle, three-point test, and cell attachment. Because of its similar characteristics with bone tissue, dentin that had been acid-treated for 6 hours was chosen to repair a periodontal defect using an induced-periodontitis canine model. Histologic measurements were taken to compare its therapeutic effects to an absorbable membrane group and an untreated group. The demineralized dentin displayed continually decreased hardness and density as the acid etching time was prolonged. Enhanced attachment and spreading of bone marrow mesenchymal stem cells were observed on the 6-hour processed dentin. Furthermore, in the demineralized dentin group, more periodontal tissues were newly formed compared with the biomembrane and untreated groups. Acid etching represents an easy and promising approach to obtain demineralized dentin with desirable properties, similar to bone, for clinical application to promote periodontal tissue regeneration.