Showing papers on "Hydrofluoric acid published in 2022"
TL;DR: In this paper , the authors present a safe route to InP/ZnSe and ZnS core/shell/shell QDs with a near-unity photoluminescence quantum yield, where the inorganic salt ZnF2 mildly reacts with carboxylic acid at a high temperature and in situ generates HF, thus facilitating epitaxial shell growth.
Abstract: High-quality InP-based quantum dots (QDs) have become very promising, environmentally benign light emitters for display applications, but their synthesis generally entails hazardous hydrofluoric acid. Here, we present a highly facile route to InP/ZnSe/ZnS core/shell/shell QDs with a near-unity photoluminescence quantum yield. As the key additive, the inorganic salt ZnF2 mildly reacts with carboxylic acid at a high temperature and in situ generates HF, which eliminates surface oxide impurities, thus facilitating epitaxial shell growth. The resulting InP/ZnSe/ZnS QDs exhibit a narrower emission line width and better thermal stability in comparison with QDs synthesized with hydrofluoric acid. Light-emitting diodes using large-sized InP/ZnSe/ZnS QDs without replacing original ligands achieve the highest peak external quantum efficiency of 22.2%, to the best of our knowledge, along with a maximum brightness of >110 000 cd/m2 and a T95 lifetime of >32 000 h at 100 cd/m2. This safe approach is anticipated to be applied for a wide range of III-V QDs.
40 citations
TL;DR: A facile and mild route to synthesize C-coated SiC nanosheets (SiC/C NSs) via wet-chemical etching in hydrofluoric acid (HF) at 60 °C for 48 h using carbon aluminum silicate (Al4SiC4) as raw materials is reported for the first time as discussed by the authors .
24 citations
TL;DR: In this article , a 0.6 wt% of LiHDS in a typical fluorine-containing carbonate-based nonaqueous electrolyte solution enables a stable Li||LiNi0.8Co0.1Mn 0.1O2 (NCM811) coin cell operation up to 1000 or 500 cycles applying a high cutoff cell voltage of 4.5 V in the 25 °C-60 °C temperature range.
Abstract: High-voltage lithium metal batteries suffer from poor cycling stability caused by the detrimental effect on the cathode of the water moisture present in the non-aqueous liquid electrolyte solution, especially at high operating temperatures (e.g., ≥60 °C). To circumvent this issue, here we report lithium hexamethyldisilazide (LiHMDS) as an electrolyte additive. We demonstrate that the addition of a 0.6 wt% of LiHMDS in a typical fluorine-containing carbonate-based non-aqueous electrolyte solution enables a stable Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) coin cell operation up to 1000 or 500 cycles applying a high cut-off cell voltage of 4.5 V in the 25 °C-60 °C temperature range. The LiHMDS acts as a scavenger for hydrofluoric acid and water and facilitates the formation of an (electro)chemical robust cathode|electrolyte interphase (CEI). The LiHMDS-derived CEI prevents the Ni dissolution of NCM811, mitigates the irreversible phase transformation from layered structure to rock-salt phase and suppresses the side reactions with the electrolyte solution.
23 citations
TL;DR: In this article, an alkaline etching process using a safer, more environmentally friendly alkali was used to pre-form a hydroxylated Ti3C2/Ti3AlC2 (h-TC/TAC) catalyst.
23 citations
TL;DR: In this paper , an environmentally friendly hydroxylated Ti 3 C 2 /Ti 3 AlC 2 (h-TC/TAC) catalysts were prepared via an alkaline etching process using a safer, more environmentally friendly alkali.
20 citations
TL;DR: In this article, the authors proposed using CO2 adsorption and desorption system and low-temperature nitrogen adaption method for coal after treatment with HF solution and HNO3 solution.
15 citations
TL;DR: In this paper , an electrolyte additive, 4-methylmorpholine-2,6-dione (MMD) with anhydride and amine functional groups, is presented, which can not only construct a dense and stable cathode-electrolyte-interface (CEI) film on solid and electrolyte interphase that can automatically improve the cycling stability of lithium-ion batteries at high temperature and high voltage, but also effectively capture hydrofluoric acid and water in the electrolyte that can adequately inhibit carbonate decomposition and protect LiCoO 2 (LCO) internal structure.
11 citations
TL;DR: In this article , a Lewis acid etching method was used to synthesize an environment-friendly MXene-based photocatalysts for CO2 photoreduction using the non-HF method.
11 citations
TL;DR: In this article , the changes in the CO 2 adsorption and desorption characteristics of coal after treatment with HF solution and HNO 3 solution were analyzed, and the effect of acid treatment was more evident than that of nitric acid.
11 citations
TL;DR: In this article , the effects of a resin cement in high and low viscosity and distinct conditioning of the intaglio surface of lithium disilicate glass-ceramic crowns on fatigue performance of the crowns were assessed.
10 citations
TL;DR: In this article , the corrosion mechanisms of three nickel-based alloys in chloride-containing hydrofluoric acid solution are studied to elucidate the effects of Cu, Cr and Mo on the surface chemistry behavior.
TL;DR: In this paper , a systematic review and meta-analysis was conducted to analyze the in vitro bond strength promoted by hydrofluoric acid+silane-containing universal adhesives and a self-etch ceramic primer to glass-ceramics and compare it with that of conventional treatments.
Abstract: Statement of problem To simplify dental procedures, multicomponent products such as universal adhesives and self-etch ceramic primers have been recommended for glass-ceramic bonding; however, studies have shown a wide range of results. Purpose The purpose of this systematic review and meta-analysis was to analyze the in vitro bond strength promoted by hydrofluoric acid+silane-containing universal adhesives and a self-etch ceramic primer to glass-ceramics and compare it with that of conventional treatments. Material and methods A systematic search was conducted in the PubMed/Medline, Scopus, LILACS, and ISI Web of Science databases up to April 2021. In vitro studies assessing the resin-mediated bond to glass-ceramics by using a self-etch ceramic primer and hydrofluoric acid+silane-containing universal adhesives and/or compared with traditional hydrofluoric acid+glass-ceramic primers were included. Selection of studies, data extraction, and risk-of-bias analysis were performed. Statistical analysis was performed by using a review management software program using a random effects model (α=.05). Results A total of 33 studies were included in the qualitative analysis and 26 studies in the quantitative analysis. Bond strength to lithium disilicate ceramic was higher when a hydrofluoric acid+glass-ceramic primer was used than when using a hydrofluoric acid+silane-containing universal adhesive (P<.05), except when 9% to 10% acid concentration was used in combination with static aging (P=.100). A self-etch ceramic primer promoted bond strength values to lithium disilicate that were similar to those of the hydrofluoric acid+glass-ceramic primer (P>.100). Conclusions Hydrofluoric acid+silane-containing universal adhesive was not as effective as the hydrofluoric acid+glass-ceramic primer in promoting bond strength to glass-ceramic. Bond strength values generated by a self-etch ceramic primer to glass-ceramic were similar to those generated by the conventional treatment.
TL;DR: In this paper , a potentiometric analytical method for the major constituents of fluorosilicic acid produced during the chemical phosphate process, i.e., H2SiF6, HF and total fluoride, is presented.
TL;DR: In this article , a detailed review of glass etchings is presented, including different etch mechanisms including etch parameters and surface microstructure of the etched glass, and the use of HF buffered with NH4F solutions to improve the quality of the etch surface.
TL;DR: In this paper , the best surface treatment for the repair of resin nanoceramics and polymer-infiltrated ceramics (PICs) is discussed.
Abstract: Statement of problem Which surface treatment provides the optimal bond strength (BS) for the repair of resin nanoceramics (RNCs) and polymer-infiltrated ceramics (PICs) is unclear. Purpose The purpose of this systematic review and meta-analysis of in vitro studies was to determine the best surface treatment protocols for the repair of PICs and RNCs. Material and methods The PubMed, Scopus, and Web of Science electronic databases were searched to select in vitro studies in English up to March 2020. Studies with fewer than 5 specimens, those that did not evaluate the BS of PICs or RNCs, and those with aging for fewer than 30 days and 5000 cycles were excluded. Data sets were extracted, and the mean differences were analyzed by using a systematic review software program. Results Among 284 potentially eligible studies, 21 were selected for full-text analysis, and 9 were included in the systematic review, of which 6 were used in the meta-analysis. The meta-analyses were performed for each treatment surface versus their respective control group and their combinations according to material: RNCs and PICs. For RNCs, airborne-particle abrasion with aluminum oxide (Al2O3) treatment was statistically higher than tribochemical silica airborne-particle abrasion (CoJet) (P=.02, I2=90%) and that in the hydrofluoric acid (HF) (P<.001, I2=0%) groups and was statistically similar to diamond rotary instrument grinding (P=.40, I2=54%). For PICs, the treatment with hydrofluoric acid (HF) was statistically significantly higher than with CoJet (P=.03, I2=62%) and airborne-particle abrasion with Al2O3 (P<.001, I2=98%). Conclusions The best surface treatment protocol for repair varied according to the restorative material. HF followed by silanization is suggested for PICs, and airborne-particle abrasion with Al2O3 or preparation with a diamond rotary instrument for RNCs.
TL;DR: In this article , a NaOH roasting approach was employed, by which LiF is converted to NaF and LiOH at 350 °C and thereby avoids the generation of HF.
Abstract: Recycling anode materials from spent lithium-ion batteries (LIBs) plays a significant role in relieving the environmental pollution and shortage of graphite and lithium resources. Most of the current routes employed mineral acids to leach out Li from the graphite anode, inevitably producing hazardous hydrofluoric acid (HF) because some Li exists in the form of lithium fluoride (LiF). In this study, we employ a NaOH roasting approach, by which LiF is converted to NaF and LiOH at 350 °C and thereby avoids the generation of HF. After roasting, the Li and graphite can be separated by a water leaching process without using mineral acids. The leaching efficiency of Li is close to 100%. The regeneration process of NaOH was also discussed considering the large-scale application. Additionally, the recovered graphite delivered an initial charge capacity of 370.8 mA h g–1 and a Coulombic efficiency of 90.05%, showing the comparable performances to the commercial graphite. Overall, the alkaline roasting approach does not use mineral acids and thus avoids generating toxic HF and waste acids, promising a green way to recycle anode materials from various spent LIBs.
TL;DR: A clean and safe microwave-assisted procedure to induce the evaporative migration of hydrofluoric acid inside a sealed "vessel-inside-vessel" system was proposed in this paper .
Abstract: The complete dissolution of silicate-containing materials, often necessary for elemental determination, is generally performed by microwave-assisted digestion involving the forced use of hydrofluoric acid (HF). Although highly efficient in dissolving silicates, this acid exhibits many detrimental effects (e.g., formation of precipitates, corrosiveness to glassware) that make its removal after digestion essential. The displacement of HF is normally achieved by evaporation in open-vessel systems: atmospheric contamination or loss of analytes can occur when fuming-off HF owing to the non-ultraclean conditions necessarily adopted for safety reasons. This aspect strongly hinders determination at the ultra-trace level. To overcome this issue, we propose a clean and safe microwave-assisted procedure to induce the evaporative migration of HF inside a sealed “vessel-inside-vessel” system: up to 99.9% of HF can be removed by performing two additional microwave cycles after sample dissolution. HF migrates from the digestion solution to a scavenger (ultrapure H2O) via a simple physical mechanism, and then, it can be safely dismissed/recycled. The procedure was validated by a soil reference material (NIST 2710), and no external or cross-contamination was observed for the 27 trace elements studied. The results demonstrate the suitability of this protocol for ultra-trace analysis when the utilization of HF is mandatory.
01 Dec 2022
TL;DR: A systematic review and meta-analysis were conducted to assess the effect of milling, fitting adjustments, and hydrofluoric acid etching (HF) on the flexural strength and roughness of CAD-CAM glass-ceramics as discussed by the authors .
Abstract: Whether procedures performed before the cementation of computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramic restorations, including milling, fitting adjustment, and hydrofluoric acid etching introduce defects on the ceramic surface that affect the mechanical and surface properties is unclear.A systematic review and meta-analysis were conducted to assess the effect of milling, fitting adjustments, and hydrofluoric acid etching (HF) on the flexural strength and roughness (Ra) of CAD-CAM glass-ceramics.Literature searches were performed up to June 2020 in the PubMed/MEDLINE, Web of Science, and Scopus databases, with no publication year or language limits. The focused question was "Do milling, fitting adjustments, and hydrofluoric acid etching affect the flexural strength and roughness of CAD-CAM glass-ceramics?" For the meta-analysis, flexural strength and Ra data on milling, fitting adjustment, and HF etching versus control (polishing) were analyzed globally. A subgroup analysis assessed the effect of etching parameters (HF concentration and time) on the flexural strength and roughness of CAD-CAM glass-ceramics with different microstructures. Comparisons were performed with random-effect models at 5% significance.Fourteen studies from 2764 potentially relevant records were included in the qualitative syntheses, and 12 in the meta-analysis. Milling and fitting adjustments increased roughness and reduced the flexural strength of CAD-CAM glass-ceramics. The effect of HF etching was dependent on the glass-ceramic microstructure, HF concentration, and etching time. For feldspathic- and leucite-reinforced ceramics, HF 5% applied for between 30 and 120 seconds increased roughness without affecting flexural strength. For lithium disilicate glass-ceramics, HF concentrations greater than 4.9% used for 20 seconds or more reduced the strength without affecting the surface roughness.The flexural strength of CAD-CAM glass-ceramic is reduced by grinding procedures such as milling and fitting adjustment. Ceramic microstructure, HF concentration, and etching time determined the effect of hydrofluoric acid etching on the flexural strength and surface roughness of glass-ceramic materials.
TL;DR: In this article , a detailed study of the synthesis of UiO-66 was conducted with hydrobromic (HBr) acid as a modulator for the first time, at a high concentration of precursor solution (ZrCl4 and H2BDC, both 0.2 mol L−1).
Abstract: The use of large amounts of deleterious solvents in the synthesis of metal–organic frameworks (MOFs) is one of the important factors limiting their application in industry. Herein, we present a detailed study of the synthesis of UiO-66, which was conducted with hydrobromic (HBr) acid as a modulator for the first time, at a high concentration of precursor solution (ZrCl4 and H2BDC, both 0.2 mol L−1). Powder crystals with atypical cuboctahedron structure were obtained which indicated that the HBr acid modulator played roles by competitive coordination and deprotonation modulation, thereby controlling the processes of nucleation and crystal growth. The properties of the obtained materials were systematically characterized and compared with those of materials synthesized with hydrofluoric (HF) acid and hydrochloric (HCl) acid modulators. Despite the high concentration of defectivity, the UiO-66 material synthesized with the HBr acid additive has the characteristics of larger specific surface area, excellent thermal stability and higher porosity in the structure. Besides that, the present protocol has the advantages of high reaction mass efficiency (RME), and feasibility of scalable synthesis, providing a facile and sustainable route to diverse Zr-based MOFs.
TL;DR: In this paper , a modified method is developed for synthesizing high-quality 2D V2C MXene, where a mixture of sodium fluoride (NaF) and hydrochloric acid (HCl) was used as the etching agent, where V2AlC can be gently etched by a hydrothermal reactor assisted method.
Abstract: Two-dimensional (2D) V2C MXene has fascinating potential for use as electrodes in high-energy-density supercapacitors because of its excellent electrical conductivity and large specific surface area. However, it is not feasible to synthesize V2C by etching vanadium carbon aluminide (V2AlC) with hydrofluoric acid, which is commonly used for preparing other MXenes. In this work, a modified method is developed for synthesizing high-quality 2D V2C. A mixture of sodium fluoride (NaF) and hydrochloric acid (HCl) was used as the etching agent, where V2AlC can be gently etched by a hydrothermal reactor-assisted method. As electrode materials for supercapacitors, V2C shows the characteristics of electric double layer capacitance. The electrochemical results show high specific capacitance (223.5 F/g in 1 M Na2SO4 at a current density of 100 mA/g) and good cycling stability (the capacitance retention rate can be maintained at 94.7% after 5000 cycles). This work provides a new method for the synthesis of high-quality V2C for application in related fields.
TL;DR: In this article , the poisoning effects of cerium oxide (CeO2) as the contaminant on the performance of proton exchange membrane fuel cells (PEMFCs) are evaluated.
Abstract: In this study, the poisoning effects of cerium oxide (CeO2) as the contaminant on the performance of proton exchange membrane fuel cells (PEMFCs) are evaluated. An experimental setup was developed to analyze the performance characteristic (I-V) curves in contaminated and non-contaminated conditions. Focused ion-beam scanning electron microscopy (FIB-SEM) cross-section images were obtained as an input for the energy dispersive X-ray (EDX) analysis. The results of the EDX analysis verified the presence of CeO2 in the contaminated membrane electrode assembly (MEA), in addition to fluorine and sulfur. EDX analysis also revealed that as a result of CeO2 contamination, sulfur and fluorine would be distributed all around the MEA, instead of being only in the membrane. The results illustrate that hydrofluoric acid (HF), sulfuric acid (H2SO4), and fluorinated polymer fragments are released, which enhance the crossover of the reactant gases through the membrane, hence reducing the cell’s performance. The I-V characteristic curves proved that the non-contaminated PEMFC setup had double the performance of the contaminated PEMFC.
TL;DR: In this article , the authors evaluated the influence of surface treatment and storage regimen on the fatigue performance of simplified lithium disilicate glass-ceramic restorations, and found that the surface treatment led to noteworthy surface topographical alterations.
Abstract: This study evaluated the influence of ceramic surface conditioning and storage regimen (baseline vs. aging) on the fatigue performance of simplified lithium disilicate glass-ceramic restorations. A total of 90 ceramic discs (Ø= 10 mm; thickness= 1.0 mm) were allocated into 6 groups (n= 15), considering 2 factors: "ceramic surface treatment" - CA (only silane-based coupling agent, Monobond N), HF (5% hydrofluoric acid etching), or HF+CA (5% HF acid etching plus silane-based coupling agent); and "storage regimen" - baseline (24 hours - 5 days of distilled water at 37 °C), or long-term aging (180 days of distilled water at 37 °C + 25,000 thermal cycles). After intaglio ceramic conditioning, adhesive bonding (Multilink N) was performed onto epoxy resin discs (Ø= 10 mm; thickness= 2.5 mm) and the bonded sets were subjected to step-stress fatigue tests (initial load: 200 N; step-size: 50 N; 10,000 cycles per step; 20 Hz). Fatigue data were analyzed using Kaplan-Meier and Weibull statistical analyses. Fractography and topography analyses were also conducted. The fatigue findings demonstrated that the performance among groups for both baseline and aging conditions maintained a tendency: the CA groups had the worst behavior (baseline: 893 N/143,667 cycles; aging: 639 N/84,179 cycles), while the surface etching with HF (baseline: 1247 N/214,333 cycles; aging: 816.67 N/128,333 cycles) and HF+CA groups (baseline: 1290 N/222,333 cycles; aging: 900 N/145,000 cycles) had no statistically significant difference between them. The aging protocol reduced the performance of all groups. The groups with better fatigue performance (HF and HF+CA) did not have statistical differences regarding structural reliability (Weibull modulus). Most failures were radial cracks from the cementation interface, except for CA aging specimens, with 27% failing from debonding. The HF etching led to noteworthy surface topographical alterations. Micromechanical interlocking resulting from HF acid etching remained prevalent in the fatigue behavior. Thus, the silane-based coupling agent (Monobond N) does not need to be applied after HF etching in terms of fatigue behavior outcomes.
TL;DR: In this article , the micro-nano hierarchical porous NiCu catalyst was synthesized by electrochemical dealloying of Zr70Ni15Cu15 (at %) metallic glass in 0.05 M hydrofluoric acid (HF) solution at 0.3 V for 1500 s.
TL;DR: In this paper , the authors optimized the composition of glass by replacing SiO2 with B2O3, and the influence of glass composition on structure and performance was studied, and they found that the incorporation of boron oxide improved the overall degree of polymerization and connectivity of the lithium aluminosilicate glass network structure, which led to a decrease in the thermal expansion coefficient of the glass and an increase in Vickers hardness and density.
Abstract: Based on lithium aluminosilicate glass, the composition of glass was optimized by replacing SiO2 with B2O3, and the influence of glass composition on structure and performance was studied. With the increase in B2O3 concentrations from 0 to 6.5 mol%, Al2O3 always existed in the form of four-coordinated [AlO4] in the network structure, and B2O3 mainly entered the network in the form of four-coordinated [BO4]. The content of Si-O-Si linkages (Q4(0Al)) was always dominant. The incorporation of boron oxide improved the overall degree of polymerization and connectivity of the lithium aluminosilicate glass network structure. An increase in the degree of network polymerization led to a decrease in the thermal expansion coefficient of the glass and an increase in Vickers hardness and density. The durability of the glass in hydrofluoric acid and NaOH and KOH solutions was enhanced overall.
TL;DR: The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks.
Abstract: This study aims to compare the shear bond strength (SBS) of a direct resin composite to CAD-CAM resin composite blocks treated with different surface treatments: micromechanical, chemical or a combination of both. Eight CAD-CAM resin composite blocks, namely Brilliant Crios, Cerasmart 270, Vita Enamic, Grandio block, Katana Avencia, Lava Ultimate, Tetric CAD and Shofu Block HC were chosen. The micromechanical surface treatment protocols tested were hydrofluoric acid, polyacrylic acid or sandblasting, and the chemical one was a universal primer. These treated CAD-CAM blocks were tested to determine the SBS of a light-curing composite resin Z100 bonded to their surface. Two-way ANOVA followed by Tukey’s post hoc test was used to investigate the difference in SBS. Failures were analyzed by Fisher’s exact test. Bonding interfaces were examined by scanning electron microscopy. The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks. The use of universal primer does not improve SBS values on dispersed filler composite blocks. For PICN blocks, the use of universal primer significantly increases SBS values when combined with hydrofluoric acid etching.
TL;DR: In this paper , an ultrasound-assisted approach to synthesize Ti3C2Tx MXene material by using Ti3AlC2 as the precursor was demonstrated, which greatly reduced the etching time to 8 h while typically 24 h is sufficient in dilute hydrofluoric acid.
TL;DR: The combination of AA, AUB, and Filtek Z350 produced the highest shear bond strength (SBS), followed by HFA, Aub, andfiltek Z 350.
Abstract: Background: We aim to evaluate the effect of surface conditioning, bonding agents and composite types on surface roughness (SR) and shear bond strength (SBS) of clear aligner composite attachments bonded to ceramics. Methods: One hundred and eighty IPS e.max CAD specimens were prepared. For SR, 60 specimens were divided according to surface conditioning (n = 15) into four groups: control, 9.6% hydrofluoric acid (HFA), 37% phosphoric acid (PhA), air abrasion (AA). SR was measured using a Profilometer and Atomic Force Microscopy. For SBS, 120 specimens were divided according to conditioning methods (n = 40) (9.6% HFA and 37% PhA or AA), then according to bonding agents (n = 20) (Assure universal bond (AUB) or Single bond universal (SBU)) and then according to composite type (n = 10): Filtek™ Z350 and Filtek™ Z350 XT flowable composite. SBS was measured using Instron testing machine. Descriptive and group comparison were calculated (p < 0.05). Results: AA had the highest SR, while the control had the lowest SR (p < 0.05). HFA had the highest, but insignificant SBS, followed by AA (p > 0.05). AUB had higher SBS than SBU (p < 0.001). Filtek™ Z350 produced higher SBS than Filtek™ Z350 XT flowable composite (p < 0.01). Conclusion: The combination of AA, AUB, and Filtek Z350 produced the highest SBS, followed by HFA, AUB, and Filtek Z350.
TL;DR: In this article , an environment-friendly and cost-effective approach to treat concentrated hydrofluoric/hexafluorosilicic acid wastewater (∼117 g F−/L) obtained from an optoelectronic industry in Taiwan and to recover fluoride as the high purity CaF2, as well as to reduce the amount of final waste disposal.
TL;DR: In this article , an etchant consisting of a standard solution of sulphuric acid and phosphoric acid (96 vol% H2SO4: 85 vol% h3PO4, 3:1 vol%) at 180 °C is utilized.
Abstract: In this paper a processing technique for sapphire is presented which combines laser-induced amorphization and subsequent selective wet etching of amorphized sapphire as well as anisotropic wet etching of single-crystalline sapphire (α-Al2O3). Using this technique, microstructures can be realized on the surface and in the bulk of sapphire substrates. By focusing ultra-short laser pulses inside sapphire, its structure can be transformed from crystalline into amorphous. The modified material can be selectively removed using etchants, such as hydrofluoric acid or potassium hydroxide (KOH), solely dissolving the amorphized part. In this work, however, an etchant consisting of a standard solution of sulphuric acid and phosphoric acid (96 vol% H2SO4: 85 vol% H3PO4, 3:1 vol%) at 180 °C is utilized. This method allows the realization of structures which are impossible to achieve when using conventional etchants which solely dissolve the amorphized sapphire. Ultrashort pulsed laser irradiation (230 fs) is used in this study as starting point for the subsequent anisotropic etching to form microstructures on the surface or in the bulk of sapphire that are terminated by characteristic crystal planes. In particular, the appearance of etching-induced patterns formed by stacks of rhombohedra is shown for structures below the surface, whereas triangular pits are achieved in surface processing.
TL;DR: In this paper , the effect of cold atmospheric plasma (CAP) treatment on resin nanoceramic (RNC) surface state and its bond strength with resin cement was investigated.
Abstract: The purpose of this study was to investigate the effect of cold atmospheric plasma (CAP) treatment on resin nanoceramic (RNC) surface state and its bond strength with resin cement. RNC with different surface treatments were prepared: control, sandblasting treatment (SB), hydrofluoric acid etching (HF) and plasma treatment of helium gas (CAP-He) and argon gas (CAP-Ar). The prepared samples were measured by SEM, Ra, Rz, contact angle goniometer, and XPS for surface characteristics. The shear bond test of RNC was examined in nine groups: SB + saline coupling agent (SL), HF + SL, CAP-He/Ar, CAP-He/Ar + SL, SB + CAP-He/Ar + SL, and control. The bond strength between RNC and resin cement was compared using shear bond strength test, before and after thermocycling. After CAP irradiation, the surface topography maintained, while the surface water contact angle was significantly reduced to 10.18° ± 1.36° (CAP-He) and 7.58° ± 1.79° (CAP-Ar). The removal of carbon contamination and inducing of oxygen radicals was detected after CAP treatment. The bond strength was improved by CAP treatment, but varied on CAP gas species and combination methods. CAP of Ar gas had better SBS than He gas. After thermocycling, CAP-Ar + SL showed the maximized shear bond strength (32.38 ± 1.42 MPa), even higher than SB + SL group (30.08 ± 2.80 MPa, p < 0.05). In conclusion, CAP treatment of helium and argon can improve the bonding properties of RNC by improving surface wettability, and CAP of argon gas combined with silane coupling agent shows the highest bond strength.