Hydrofluoric Acid Etching Time Research Articles

MXene 2D Ti3C2Tx production and spin-orbit effect (SOI) of Ti3C2(OH)2 in the Electronic Structure

Research on new-generation materials to meet the energy needs has begun to attract attention. Energy storage in materials is a general research subject. As a result of the reaction of MAX phase 312 Ti3SiC2 powder with hydrofluoric acid, a new 2D nanosized layered powder called MXene, similar to graphene, was obtained. MXenes, which have been studied in various sectors, especially energy, have attracted the attention of researchers owing to their multilayered structure. When Ti3SiC2 powder was treated with hydrofluoric acid (HF), an accordion-like two-dimensional Ti3C2Tx MXene structure was formed. In MXenes, surface coatings such as –O,–OH, and –F groups, which determine and affect various aspects of 2D materials, such as conductivity, constitute the application area. In this study, Ti3C2(OH)2–O and/or–OH surface terminations were examined using density functional theory (DFT) with the effect of hydrofluoric acid etching time. X-ray diffraction (XRD) and scanning electron microscopy (SEM and FESEM) were used to examine the MXene-phase Ti3C2Tx powder and first-principles calculations were performed. The structural and electronic properties of MAX and MXene compounds were obtained. The spin-orbit effect (SOI) was examined in the electronic structure of MXene. The total and partial densities of states (DOS) with and without spin orbit were calculated.

Effect of Hydrofluoric Acid Etching Time on Shear Bond Strength of Resin Cement to Different CAD/CAM Ceramic Materials

Effect of Hydrofluoric Acid Etching Time on Shear Bond Strength of Resin Cement to Different CAD/CAM Ceramic Materials

Fabrication and Characterizations of Superhydrophobic Surface with Superior Corrosion Inhibition on Q345b Steel Substrate

AbstractIn this work, a coherent and cost‐effective method is developed to achieve superhydrophobicity and excellent corrosion resistance on Q345B steel surfaces. The method involves sequential etching with hydrochloric acid and hydrofluoric acid, passivation with potassium permanganate, treatment with bis‐(γ‐triethoxysilylpropyl)‐tetrasulfide (KHSi69，BT), and modification with hydrophobic SiO2 nanoparticles. The effects of etching and passivation time, including SiO2 doping ratio on the wettability and corrosion resistance of the prepared surfaces are investigated. The results demonstrate that the surface exhibits a micro–nano multilayer and modified nano‐multiscale cluster structure which has a contact angle (CA) of 155.8 ± 1.7° and a sliding angle (SA) of 5 ± 0.5° by employing the following conditions: hydrochloric acid etching time of 10 min, hydrofluoric acid etching time of 25 min, passivation time of 300 min, and a 3 wt% SiO2 doping ratio. Moreover, the surface displays extremely weak droplet adhesion and excellent self‐cleaning properties. Furthermore, the corrosion inhibition of the prepared steel surface is evaluated using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results indicate that the corrosion inhibition efficiency of the superhydrophobic surface is enhanced by about 89.95% compared to the traditional two‐step processing involving etching and modification. These findings expand the potential applications of steel.

Bond strength to ZLS ceramics at different etching times and cementation protocols after aging

Objective: To assess the influence of 5% hydrofluoric acid etching time (ET), cementation protocol (CP), and thermal cycling (TC) aging on the microshear bond strength (µSBS) of zirconia-reinforced lithium silicate ceramic (ZLS) to adhesive resin cement. Material and Methods: Ten VITA Suprinity® ceramic blocks were cut in 120 slices (1.4 mm thickness) and randomly assigned to 12 groups (n = 10) according to the combination of factors (2x3x2 design): etching time (20 or 30 s), cementation protocol (silane + universal adhesive + resin cement; universal adhesive + resin cement; silane + resin cement) and thermal cycling (cycled or no-cycled). RelyX Ceramic Primer and Scotchbond™ Universal Adhesive were used respectively as silane (S) and universal adhesive (Ua). Ceramic surface was etched, and the cementation protocol performed on the delimited bonding area. Then, resin cement (RelyX™ Ultimate Cement [Rc]) cylinders were bonded and light cured. After, specimens were stored in deionized water at 37°C for 7 days and subjected to the µSBS test. Results: Data passed the normality test and three-way ANOVA analysis showed statistical difference (p<0.01) for isolated; double (ET/TC) (p<0.05), and triple (p<0.05) factor interactions. Conclusion: The combination 30s etching-Ua-Rc presented higher adhesive bond strength after thermal aging.

Influence of hydrofluoric acid etching time and concentration on shear bond strength of metal brackets to ceramic surfaces

Abstract Introduction Surface treatment prior to bonding ceramic brackets with hydrofluoric acid is indicated because of its ability to promote morphological changes necessary for adhesion. Objective To evaluate the shear bond strength (RUC) of metal brackets bonded to the feldspar ceramic surface under the action of hydrofluoric acid (AF), in different concentrations (5% and 10%) and different application times (30 and 60 seconds). Material and method Four nickel-chrome metal blocks that received an application of feldspathic ceramic were used, to which 80 metal brackets (Abzil/3M) were bonded and divided into 4 Groups (n=20) according to the acid etching procedure. The blocks were etched with 5% hydrofluoric acid for 30 and 60 seconds (AF5/30 and AF5/60, respectively) and 10% hydrofluoric acid for 30 and 60 seconds (AF10/30, AF10/60, respectively). The resin composite used was Transbond XT (3M) and the presence of a glazer was maintained on the ceramic surface. The specimens were placed on a Universal test machine Instron 4411 (Instron Corp, USA) to which a chisel was adapted to perform the shear test at a speed of 1mm/min. The data were submitted to the analysis of variance (ANOVA) and the Adhesive Remnant Index was evaluated. Result In the time interval of 30 seconds, there was no significant difference for the 5% and 10% hydrofluoric acid concentrations. In the 60-second time interval, the 10% concentration showed significantly higher shear bond strength values (p<0.05). The ARI showed predominance of scores 1 and 2. Conclusion It was concluded that 10% hydrofluoric acid showed higher shear bond strength values in 60 seconds of etching, while 5% hydrofluoric acid showed no significant difference between the etching times.

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.

Effect of hydrofluoric acid etching time and resin bonding on the flexural strength of lithium disilicate glass ceramic

To analyze the effect of hydrofluoric acid(HFA) etching time and resin bonding on the flexural strength of IPS e.max® Press glass ceramic, and evaluate the efficacy of resin cements to seal the cracks of the etched ceramic. Two hundred and twenty-five bars (25.0 mm×3.0 mm×2.0 mm) were made from IPS e.max® Press ingots using lost-wax, hot-pressed ceramic fabrication technology and randomly divided into five groups, forty-five each.In each group, the surfaces of ceramic bars were etched by 9.5% HFA gel for 0, 20, 40, 60 and 120 s respectively. Three specimens from each group were selected to observe the microstructure by the field emission scanning electron microscope (FE-SEM). Then each group were randomly subdivided into two subgroups (n = 20).One subgroup were coverd with a thin (approximately 0.1 mm) layer of resin cement (Variolink N), whereas the other subgroup remained unaltered.Half of the specimens were stored in 37°C water bath for 24 h and the other half went through thermocycle 10 000 times before 3-point bending test to determine their flexural strength.Interfaces between resin cement and etched ceramic were examined with FE-SEM. FE-SEM results showed that etching with HFA resulted in preferential dissolution of glass ceramic, and partially supported crystals within the glass matrix were lost with the increasing of etching time.FE-SEM indicated that resin cement sealed the cracks and defects and bonded tightly to etched ceramic surface. The mean flexural strength values of group 0, 20, 40, 60 and 120 s were (384 ± 33), (347 ± 43), (330 ± 53), (327 ± 67) , and (317 ± 41) MPa respectively. The mean flexural strength of each group except group 0 s increased significantly to (420 ± 31), (435 ± 50), (400 ± 39), and (412 ± 58) MPa respectively after the application of resin cement. Overtime HFA etching could have a wakening effect on IPS e.max® Press glass-ceramic. The application of dual-curing resin cement can compensate the strength loss of the etched glass ceramic.

Effect of hydrofluoric acid etching time on the resin bond durability of glass ceramic

To analyze the effect of hydrofluoric acid (HFA) etching time on the resin bond durability of glass ceramic. Three groups of samples of machinable glass ceramic (ProCAD) were etched by 4.8% HFA for 0, 30 and 60 s respectively. The roughness parameters (Ra, Sm, S) and surface area of the samples, were measured with a 3D-laser scanning microscope. Then the ceramic surfaces were bonded with four resin cements (silane coupler/resin cement), which were Monobond S/Variolink II, Clearfil Ceramic Primer/Clearfil Esthetic Cement, GC Ceramic Primer/Linkmax HV, and Porcelain Liner M/SuperBond. The micro-bond strengths between the ceramic and the resin were tested at baseline and after the samples had been treated in 30000 thermal cycles. The Ra [(3.89+/-1.94), (12.53+/-0.80), (13.58+/-1.10) microm] and surface area [(7.81+/-2.96), (30.18+/-2.05), (34.16+/-1.97) mm2] of ceramic increased with the increase of HFA etching time. The thermal cycling test reduced the bond strength of all test groups. The bond strength of Monobond S/Variolink II group [(3.59+/-3.51), (16.18+/-2.62), (20.33+/-2.45) MPa] and Clearfil Ceramic Primer/Clearfil Esthetic Cement group [(4.74+/-2.08), (7.77+/-1.55), (13.45+/-3.75) MPa] increased with the increase of HFA etching time; 30 s HFA etching group of Porcelain Liner M/SuperBond had higher bond strength [(22.00+/-1.64) MPa] than its 0 s HFA etching group [(12.96+/-4.17) MPa], and no significant difference was found between the 30 s and 60 s HFA etching groups of Porcelain Liner M/SuperBond [(20.42+/-3.01) MPa]. HFA etching time had no effect on the bond strength of GC Ceramic Primer/Linkmax HV. HFA etching can improve the resin bond durability of glass ceramic, and the etching time is not only related to the change of ceramic surface roughness and area, but also to the characteristics of resins.

Effect of hydrofluoric acid etching time on Ni/6H-SiC contacts

The effect of hydrofluoric acid （HF） etching time on Ni/6H-SiC ohmic contacts was investigated． The as-deposited Ni/6H-SiC contacts prepared by 6H-SiC substrates which have been subjected to different HF etching time have different I-V characteristics． For SiC substrates etched for less than 12 hours, the contacts were rectifying, and excellent linear curves were observed after high temperature thermal annealing．X_ray diffraction, Auger electronic spectroscopy and low_energy reflection electron energy loss spectroscopy showed that Ni2Si and amorphous C were the main reaction products after annealing.For SiC substrate etched for 24 hours, the as-deposited Ni/6H-SiC contact was ohmic． The carbon-enriched layer （CEL） on the SiC surface plays an important role in the formation of ohmic contact．