Acid Etching Time Research Articles

Acid-etching protocol for bioceramic cements: Evaluation of bond strength, compression and morphology.

To establish an acid-etching protocol for Biodentine and Cimmo DTA, evaluating compressive strength, bond strength, surface morphology in scanning electron microscope and failure modes after different etching times. Two test specimens were prepared for each cement and divided into four groups (n = 12) according to the acid-etching time (0, 5, 10 and 15 s). Compressive strength was tested using a universal testing machine, while bond strength was evaluated after bonding with Filtek Bulk Flow resin using Universal ESPE Single Bond adhesive. Failures were classified as surface-adhesive, cement-cohesive, resin-cohesive and mixed. Biodentine showed significantly higher compressive strength than Cimmo DTA (p < 0.001), regardless of acid etch time (p < 0.001). Different acid-etching strategies are required for Biodentine and Cimmo DTA, with Biodentine requiring selective etching and Cimmo DTA requiring a full 15-s etch to optimise bond strength properties.

Aging damage characteristics of acid‐etched sandstone samples

AbstractTo investigate the erosive damage effect of the acidic solution on sandstone, experiments were conducted to examine the macro‐ and micro‐characteristics of sandstone samples under different acid etching times. Microscopic morphology changes, pore structure characteristics, mineral composition changes, and mechanical response characteristics were obtained before and after acid etching. Finally, a comprehensive evaluation index for acid etching damage was proposed. The results show that: (1) Acidic solution will erode the sandstone skeleton and cause the sandstone to collapse. The etched surface appears “flocculent” and yellow sediment is produced. (2) The pores in sandstone samples are mainly micro‐ and mesopores, and the total porosity increases exponentially with the duration of acid etching. The volume fraction of micropores can reach up to 81.5%. (3) The acid etching process of sandstone samples includes physical diffusion and chemical dissolution, which can be divided into four stages and three regions from the outside to the inside. After acid etching, the uniaxial compression failure mode of the sample changes from shear to mixed shear‐tensile failure. (4) The comprehensive evaluation index based on three failure modes generated during the loading process shows good consistency with the overall changes of characteristics parameters such as elastic modulus, peak stress, and peak strain. The research findings of this paper can provide theoretical support for the assessment of rock mass stability and disaster prevention in acidic environments.

Evaluation of Etching Time Effect on Shear Bond Strength of Orthodontic Brackets Bonded with Self-Adhesive Composite: An in-Vitro Study

Introduction: Precise acid etching of the tooth surface is a significant factor in the strength of the bracket bond. The current study aimed to determine the effect of different application times of acid etching on the shear bond strength of metallic orthodontic brackets under controlled laboratory conditions. Methods: Sixty intact premolar teeth were selected for this in-vitro study. The samples were divided into four groups based on the different acid etching times: 20, 25, 30, and 35 seconds. The teeth surfaces were etched with 37% phosphoric acid according to the specified times, and brackets were bonded to the enamel surface using GC Ortho connect composite. Shear bond strength values of the brackets was measured using a Universal Testing Machine. The amount of Adhesive Remnant Index was also observed using a stereomicroscope. Additionally, the surface roughness of the tooth enamel after bracket bonding was examined using SEM. The results related to shear bond strength were analyzed with one-way ANOVA statistical test and using SPSS version 16 software. The non-parametric Kruskal Wallis (Wallis-Kruskal) test was also used to check the frequency of ARI index. Results: The highest shear bond strength was observed at 25 seconds, and the lowest at 30 seconds. However, there was no significant difference in the shear bond strength of brackets was observed among the four groups (p=0.186). The highest ARI score was observed at 35 seconds, and the lowest at 20 seconds. No statistically significant difference was observed in the ARI scores in different groups. SEM images revealed that the enamel surface porosity was highest at 20 seconds. Conclusion: The results indicate that the shear bond strength and ARI at different acid etching times do not significantly differ. Therefore, orthodontic bracket bonding can be performed with less acid etching time.

Effects of lactic acid etching on immediate and aged bond strength of resin-dentin bonding interface.

To investigate the effects of lactic acid etching on the immediate and aged bond strength of the resin-dentin bonding interface, the resin-dentin bonding interface was evaluated 24 hours and 6 months later. A total of 42 isolated third molars were randomly divided into 6 experimental groups according to different lactate concentration (35%, 40%, 45%) and acid etching time (30 s, 45 s), with 37% phosphoric acid etching 15 s as a control. In each group, dentin samples were etched under different acidic conditions and bonded with Adper Single Bond 2 (3M ESPE) as directed. The immediate group was immediately stored in deionized water at 37 °C for 24 h, and the aging group was stored in artificial saliva at 37 °C for 6 months. Immediate and aged bond strengths were measured by a micro-tensile tester, and the specimen fracture surface was observed under a microscope. 14 isolated third molars were randomly divided into 7 groups, and each group was etched with acid. Collagen fibers morphology in dentin was examined after gradient dehydration with ethanol by scanning electron microscopy (SEM). Statistically, there was no difference between the resin-dentin immediate bonding strength of 35% lactic acid for 30 s and 37% phosphoric acid for 15 s, but the aged bond strength was greater than that of the phosphoric acid group. According to scanning electron microscope observations, the collagen fiber morphology in 35% and 40% lactate etching dentin 30 s groups was relatively intact compared with other groups. In conclusion, 35% lactic acid etching of dentin 30 s ensures both immediate and aged resin-dentin bond strength.

Peroxydisulfate activation by copper nanoparticles doped highly graphitized hollow carbon spheres for thiocyanate degradation

Thiocyanate (SCN-) is a toxic and refractory inorganic pollutant commonly found in industrial wastewater. This paper proposes an innovative solution to enhance the activation of peroxydisulfate (PDS) by designing a highly graphitized hollow carbon nanosphere structure catalyst doped with copper nanoparticles, thereby achieving efficient and complete degradation of SCN-. Specifically, the active sites and electron transfer ability of the catalyst were improved by controlling the pyrolysis temperature and acid etching time during the catalyst preparation process, thereby optimizing the PDS activation rate and SCN- degradation rate. In the optimized Cu-NPs@C/PDS system, a low dose of Cu-NPs@C-650–6 catalyst (0.2 g/L) and PDS ([PDS]0: [SCN-]0 = 3: 1) was sufficient to achieve 100 % degradation of 100 mg/L SCN- within 20 min. The non-radical oxidation pathway combined with singlet oxygen (1O2) and direct electron transfer process was identified as the main degradation mechanism of SCN-. The unique oxidation mechanism provided a higher SCN- degradation reaction rate constant (k1 = 0.39 min−1) and stronger environmental ion resistance. Density functional theory (DFT) calculations show that the CO bond is the primary PDS active site for the formation of inside-out electron delocalization, and the S atom in SCN- is a vulnerable site. This work offers technological support for the treatment of water bodies holding emerging electron-rich pollutants in addition to fresh insights into the creation of efficient catalysts for metal-carbon composites.

Evaluation of the optimal etching times and fissure sealant materials for bonding on primary teeth enamel: An in vitro study

The recommended 15-s acid etching time expands the enamel surface and facilitates the infiltration of restorative materials. Because of this clinical advantage, 15 and 30 s have become the most prevalent acid etching times in recent years. This study aimed to evaluate the effects of conventional and self-adhesive flowable composites (SAFCs) that were etched for different durations on primary molar teeth. Teeth were divided into eight groups (n = 16) and restored either with Vertise™ Flow and orthophosphoric acid or with Conseal F and orthophosphoric acid for 15, 30, 45, or 60 s. Then, the specimens were subjected to shear stress at a cross-head speed of 1 mm/min until the bond failed. After conducting the microshear bond strength (μSBS) test, failure modes were analyzed using scanning electron microscopy at 80 × magnification. Statistical analysis was performed using Independent sample T-tests and other T-tests (p < 0.05). According to the μSBS results, a statistically significant difference was observed among all groups (p < 0.05). Additionally, there were statistically significant differences between both restorative materials after etching for 15 s (p = 0.011; p < 0.05) and 60 s (p < 0.001; p < 0.05). While adhesive-type fractures were mostly observed in the SAFC groups, mixed-type fractures analyzed by scanning electron microscopy were determined to be relatively common in the Conseal F groups. An etching time of 15 s for primary tooth enamel was recommended instead of 60 s for all fissure sealants. In addition, the application of Vertise™ Flow after 15 s of acid etching was preferred over the application of Conseal F.

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

Enhancement of bone mineral formation on Ti6Al4V surface by PM-EDCLT combined with acid etching

For Bone-anchored limb prostheses, osseointegration plays a significant role in the mechanically stable interface between bone and implants. Titanium alloy is the most usable alloy for hard tissue replacement. The drawbacks of the titanium implant are corrosion, leaching and poor osseointegration. In this research, powder mixed (hydroxyapatite) - electric discharge-assisted centreless turning (PM-EDCLT) (Impulse current- 5amp, duty factor- 57%, hydroxyapatite concentration 18 g/l, and rpm-360) and acid etching (solution – HF: HNO3: H2O = 1:2:50) were used for the surface modification of screw-fit implants. Average surface roughness value maximum in PM-EDCLT machined surface (1.249 µm) followed by PM-EDCLT machined + 5 min. Acid etching (1.055 µm), PM-EDCLT machined + 10 min. Acid etching (0.9829 µm), PM-EDCLT machined + 15 min. acid etching (0.8223 µm), bare surface with 10 min. Acid etching (0.2866 µm), 15 min. acid etching (0.2714 µm) and 5 min. Acid etching (0.1896 µm). Investigations using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) proved that the deposited layer on the powder-mixed EDCLT machined sample was hydroxyapatite. After sinking samples in the Simulated Body Fluid (SBF) solution, it was concluded that the percentage of bone minerals like oxide, Ca, and P deposition increases after increasing the acid etching time on the PM-EDCLT machined surfaces. Little effect was found on the deposition of bone minerals on the surface of acid etching only by increasing the etching time. There is a clear trend of decreasing the contact angle with increasing the acid etching time on the PM-EDCLT surfaces.

Porous hollow nanospheres nickel phosphide and its high catalytic hydrogenation performance on naomaohu coal soluble portion and model compounds

The catalytic conversion of oxygen-containing aromatic ring in lignite under mild conditions is crucial to obtain clean liquid fuel. Here, hollow nanosphere Ni3P-500–24 catalysts were prepared at a calcination temperature of 500 °C and acid-etching time of 24 h. The porous hollow nanospheres structure could expose more catalytic sites, and the electron-rich nickel exhibited a good catalytic activity. The conversion rate of benzyl phenyl ether (BPE) was 100 % (140 ℃, 1 MPa H2, 2 h), and the main products were methylcyclohexane and cyclohexanol, indicating that the catalyst had good catalytic hydrocracking performance. In addition, the catalyst exhibited certain deoxygenation activity and high product selectivity for other oxygen-containing model compounds. For the catalytic hydrogenation of Naomaohu coal (NMHC) soluble portion, the content of alkanes increased from 19 % to 47 %, while the content of oxygen-containing compounds decreased from 56 % to 21 %, which further demonstrate that the catalyst have good catalytic hydrogenation and deoxygenation performance. Density Functional Theory (DFT) calculations showed that the properties of the Ni3P-500–24 catalyst was similar to noble metal, which could activate H2 to produce two kind of active hydrogen: H radical and diatomic hydrogen. The synergistic pathways for the transfer of active hydrogen during the catalytic hydroconversion (CHC) process were analyzed. Above results could provide theoretical guidance for the conversion of lignite into high-quality clean liquid fuels.

Laboratory study on acid fracturing performance in high temperature carbonate reservoirs

In this article, we investigate acid fracturing, a promising method to increase the effectiveness of fractures in high temperature carbonate reservoirs. In order to determine the performance of acid fracturing in carbonate reservoirs, we conducted a lab scaled true triaxial acid fracturing experiment on high temperature carbonate rock. The fracture initiation, propagation behavior, and conductivity under the action of acid solution were analyzed. The 3-D micro computed tomography was applied to illuminate the fracture network patterns; coefficient of stress difference, acid etching time, and acid concentration were also analyzed. Results show acidification exhibits the lowest breakdown pressure compared with no-acidification, reduced by 58%.

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.

Hydrofluoric acid concentration and etching time affect differently the microstructure and surface properties of pressed lithium disilicate glass ceramics.

To evaluate the effect of different hydrofluoric acid concentrations and etching times on the surface, chemical composition and microstructure of lithium disilicate. Ninety specimens of pressed lithium disilicate (LDS) were obtained (IPS e.max Press, Rosetta SP and LiSi Press). The specimens of each material were divided in two groups according to the hydrofluoric acid concentration: 5% and 10% (n = 15/group), and subdivided according to the etching time: 20, 40 and 60 s (n = 5/group). Crystalline evaluations and chemical composition were performed through x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), respectively. Microstructural analyses were performed by scanning electron microscope (SEM), surface roughness (Ra), and material thickness removal evaluation. Thickness removal and Ra data were analyzed by ANOVA and Tukey test (p < 0.05). XRD demonstrated characteristic peaks of lithium disilicate crystals, lithium phosphate and of a vitreous phase for all materials. EDS identified different compositions and SEM confirmed different surface responses to acid etching protocols. Material and etching time influenced Ra and material thickness removal (p < 0.05). Hydrofluoric acid concentration and etching time affect the surface characteristics of LDS differently. LiSi Press presented higher resistance to hydrofluoric acid etching compared to e.max Press and Rosetta SP. Applying the appropriate etching protocol is pivotal to avoid excessive material removal and to prevent jeopardize the mechanical and optical properties of the material.

Investigation of Mechanical Properties Evolution and Crack Initiation Mechanisms of Deep Carbonate Rocks Affected by Acid Erosion

Deep tight-gas carbonate reservoirs have huge reserves, with the advantages of having clean and low-carbon characteristics in addition to being a sustainable and stable supply which leads to very high-quality green energy, despite its difficult extraction. The reservoirs are usually modified using acid fracturing before exploitation, but due to acid erosion, the continuous alteration of the mechanical properties of the reservoir rocks complicates the process of predicting the crack initiation pressure. This paper aims to address the difficulties in predicting the crack initiation pressure by conducting a series of acid-etching experiments on carbonate rock samples subjected to splitting and uniaxial compression tests. By examining the variations in the elastic modulus, Poisson’s ratio, tensile strength under distinct acid systems, and acid-etching durations and temperatures, a quantified mathematical model was developed. This model was integrated into a fracture-initiation pressure prediction framework, resulting in a practical and user-friendly tool for the acid fracture-initiation pressure prediction model, which was further demonstrated through field engineering validation. The findings reveal that the elastic modulus, Poisson’s ratio, and tensile strength of carbonate rocks exhibit an inverse relationship with acid-etching time and temperature. Extended acid fracturing durations and high reservoir temperatures are conducive to acid-fracturing transformations. The fracture-initiation pressure-prediction-model analysis disclosed that, compared to the gelled acid, the diverting acid demonstrates a more pronounced reduction in the reservoir fracture pressure under high-temperature and short-duration conditions. An acid system preference diagram was constructed to provide a theoretical foundation for practical engineering applications, delivering valuable insights for optimizing acid fracturing treatments in carbonate reservoirs to provide a boost for the green energy extraction of tight gas.

Hydrothermal acid etching of alumina beads and its effect on isobutane dehydrogenation performance over Pt/γ-Al2O3 catalyst

Millimeter-scale spherical alumina used as the support of Pt catalyst for isobutane dehydrogenation was prepared by alginate assisted sol-gel method, and then hydrothermal treated in 0.5 M HNO3 to improve its porous structure and surface properties. The effects of acid etching time on the composition, structure, surface acidity, redox property, catalytic dehydrogenation performance and carbon deposition of catalyst were investigated by ICP-OES, SEM, TEM, XRD, N2 adsorption-desorption, 27Al MAS NMR spectra, NH3-TPD, H2-TPR, isobutene transient response experiment and TGA. The results show that the acid treatment can effectively remove zinc species and partial aluminum from the surface of alumina beads, which can create defect sites and increase the specific surface area of alumina, thus improving the dispersion of Pt particles. In addition, acid etching significantly increases the acidity of alumina and enhances the interaction between Pt particles and alumina through the formation of defect sites. The Pt/Al2O3-NA-3 possesses the smallest size of Pt particles, the strongest Pt-alumina interaction, maximum number of acid sites and the highest isobutene yield of 33% even after 270 min reaction.

Biaxial flexure strength and physicochemical characterization of a CAD/CAM lithium disilicate ceramic: effect of etching time, silane, and adhesive applications.

To evaluate the effect of different acid etching time and bonding agent (silane and/or adhesive system) on biaxial flexural strength and physico-chemical properties of a lithium disilicate ceramic. One hundred twenty ceramic discs were made and divided into 8 groups (n = 15) according to factors "etching time" (20 and 120s) with hydrofluoric acid (HF) and "bonding agent" (C, no bonding agent; S, silane, A, adhesive; and SA, silane + adhesive). After surface treatment, a resin cement layer was applied to the surface and all specimens were subjected to biaxial flexural strength (BFS) test with treated surfaces loaded in tension (1mm/min). The Weibull analyses and complementary analyses were also performed. Statistical analysis was done with 2-way ANOVA and the Tukey test (α = 0.05). ANOVA revealed that the factors "etching time" (p = 0.0003) and "bonding agent" (p = 0.007) were statistically significant. In the overall analysis, the HF120S group (272.02 ± 35.30A MPa) presented significantly higher BFS than that of HF120C (218.45 ± 17.15CD MPa) and HF20S (228.40 ± 37.83BCDMPa). On the other hand, the HF20A group (208.92 ± 31.16D MPa) had significantly lower BFS than HF120S (272.02 ± 35.30A), HF120A (254.42 ± 26.87ABC) and HF120SA (259.30 ± 36.55AB) groups (Tukey). The Weibull modulus (m) of all groups was significantly different from each other (p = 0.000). Regardless of etching time, the application of silane alone is sufficient to increase the flexural strength of glass ceramic, eliminating the need for the application of adhesive systems. Moreover, if only silane or adhesive is applied, 120-s HF application should increase the flexural resistance of the lithium disilicate ceramic. Applications of adhesive systems after silanization can be suppressed from the surface treatment protocol of glass ceramics, since it does not improve their mechanical strength.

Robust α-Fe2O3@TiO2 Core-Shell Structures With Tunable Buffer Chambers for High-Performance Lithium Storage.

α-Fe2O3 has high potential energy storage capacity and can serve as a green and low-cost anode material for lithium-ion batteries. However, α-Fe2O3 suffers large volume expansion and pulverization. Based on DFT calculations, TiO2 can effectively maintain the integrity of the crystal structure during the discharge/charge process. Well-defined cubic α-Fe2O3 is coated with a TiO2 layer using the hydrothermal method with the assistance of oxalic acid surface treatment, and then α-Fe2O3@TiO2 with tunable buffer chambers is obtained by altering the hydrochloric acid etching time. With the joint efforts of the buffer chamber and the robust structure of the TiO2 layer, α-Fe2O3@TiO2 alleviates the expansion of α-Fe2O3 during the discharge/charge process. The optimized sample (FT-1h) achieves good cycling performance. The reversible specific capacity remains at 893.7 mA h g-1, and the Coulombic efficiency still reaches up to 98.47% after 150 cycles at a current density of 100 mA g−1. Furthermore, the reversible specific capacity can return to 555.5 mA h g−1 at 100 mA g−1 after cycling at a high current density. Hence, the buffer chamber and the robust TiO2 layer can effectively improve the cycling stability and rate performance of α-Fe2O3.

Effects of Hydrofluoric Acid Concentration and Etching Time on the Bond Strength to Ceramic-coated Zirconia.

To evaluate the effects of different hydrofluoric acid (HF) concentrations and etching times on the surface topography, roughness, and resin bond strength to ceramic-coated zirconia (CC), and to compare them with the effects of alumina air-abrasion combined with 10-MDP (AA). AA and CC specimens were divided into 12 groups (N = 10). The CC groups were etched with HF at different concentrations (5% or 9.5%) for various durations (0 min, 1 min, 2 min, 3 min, 5 min or 10 min). The surface morphology was analyzed using SEM. Energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) were performed for chemical and crystalline-phase analyses. Surface roughness (Ra) and shear bond strength (SBS) were recorded and statistically analyzed. The SBS of CC groups initially increased, but then decreased with etching time for both HF acid concentrations. The 9.5% HF group displayed more marked topographical changes and higher Ra compared with the 5% HF group for the same etching period. Mean SBS was lower in the AA group compared with the CC groups etched with 5% HF for 2-10 min and 9.5% HF for 1-3 min (p < 0.05). Different HF concentrations and etching times influenced the surface topography, roughness, and resin bond strength of/to ceramic-coated zirconia. Etching with 5% HF for 5 min and with 9.5% HF for 2 min, respectively, provided the highest SBS.

Acid etching effects on thermal stability of ΔE-effect and field sensitivity in Cr-doped Iron-based amorphous ribbons

We study the thermal stability of ΔE-effect and field sensitivity on the Fe67Co10Cr3Si5B15 (FCCSB) ribbons with different acid-etching time. The testing temperature (T) range is from 30 to 240 °C. For all samples, we observed a general feature of ΔE-effect increasing with magnetic field up to a saturation value. The slope of ΔE versus field, defined as field sensitivity, is positive in contrast to that of the samples without Cr, suggesting the Cr-adding can alter the lattice response to the field from shrink to expansion due to the antiferromagnetic interaction of Cr-Fe. Without acid treatment, the sample annealed at 390 °C under field of 2000 Oe yields a maximum ΔE-effect. With the additional acid treatment for 40 mins before annealing, the thermal stabilities of ΔE-effect and field sensitivity are enhanced. Cross section TEM images provide an evidence for the etching induced surface crystallization. Thus, we attribute the etching enhanced thermal stability of ΔE properties to the modification of interfacial stress. This study provides useful information for the application of FCCSB ribbons as a field sensor with anti-corrosion properties.

Hydrofluoric acid concentration and etching time on bond strength to lithium disilicate glass-ceramic

The objective of this study to evaluate the effect of different HF concentrations and etching times on the microshear bond strength (μSBS) of LD to resin cement. Forty LD sections (8x8 mm) of 3-mm thickness were randomly distributed (n=10) in accordance with the HF concentration (5 or 10%) and surface etching time (20 or 60 sec). The specimens were silanized and received an air-thinned layer of a light-curable adhesive. Six translucent tubes (0.8-mm diameter and 1-mm height) were positioned over each LD section, filled with resin cement and light-cured. After 24 h of storage, the tubes were carefully removed and the specimens were submitted to the μSBS test. The results submitted to a two-way analysis of variance and Sidak post hoc test (α=.05). Representative HF-etched specimens and one non-etched LD specimen were observed under a field-emission scanning electron microscope. The interaction between the HF concentrations and etching times was not significant (p=0.075). No significant differences were observed regarding HF concentrations and etching times (p=0.06 and p=0.059, respectively). Surfaces of specimens etched with 10% HF for 60 sec were found with grooves and microcracks. The μSBS of LD to resin cement was not significantly influenced by different HF concentrations and etching times; however, the LD surface morphology was found considerably modified.