Influence of acid-etching and ceramic primers on the repair of a glass ceramic

The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μT BS) between a feldspathic ceramic and two composites. Forty blocks (6.0 × 6.0 × 5.0 mm 3) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm2 ± 0.2 mm) were stored in distilled water at 37°C for 30 days and submitted to thermocycling (7,000 cycles; 5°C/55°C ± 1°C). The μT BS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (α = 0.05). The surface treatments significantly affected the results (P < 0.05); no difference was observed between the composites (P > 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength.

Broadband NIR emission in novel sol-gel Er3+-doped SiO 2-Nb2O5 glass ceramic planar waveguides for photonic applications

This paper reports on the sol-gel preparation and structural and optical characterization of new Er3+-doped SiO2-Nb 2O5 nanocomposite planar waveguides. Erbium-doped (100-x)SiO2-xNb2O5 waveguides were deposited on silica-on-silicon substrates and Si(1 0 0) by the dip-coating technique. The waveguides exhibited uniform refractive index distribution across the thickness, efficient light injection at 1538 nm, and low losses at 632 and 1538 nm. The band-gap values lied between 4.12 eV and 3.55 eV for W1-W5, respectively, showing an excellent transparency in the visible and near infrared region for the waveguides. Fourier Transform Infrared (FTIR) Spectroscopy analysis evidenced SiO2-Nb2O5 nanocomposite formation with controlled phase separation in the films. The HRTEM and XRD analyses revealed Nb2O5 orthorhombic T-phase nanocrystals dispersed in a silica-based host. Photoluminescence (PL) analysis showed a broad band emission at 1531 nm, assigned to the 4I13/2 → 4I15/2 transition of the Er3+ ions present in the nanocomposite, with a full-width at half medium of 48-68 nm, depending on the niobium content and annealing. Hence, these waveguides are excellent candidates for application in integrated optics, especially in EDWA and WDM devices. © 2012 Elsevier B.V. All rights reserved.

Upconversion luminescence in Er3+ doped Ga10Ge 25S65 glass and glass-ceramic excited in the near-infrared

The infrared-to-visible frequency upconversion was investigated in Er 3+-doped Ga10Ge25S65 glass and in the transparent glass-ceramic obtained by heat-treatment of the glass above its glass-transition temperature. Continuous-wave and pulsed lasers operating at 980 nm and 1480 nm were used as excitation sources. The green (2H 11/2 → 4I15/2; 4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) photoluminescence (PL) signals due to the Er3+ ions were characterized. The PL decay times were influenced by energy transfer among Er3+ ions, by cross-relaxation processes and by energy transfer from the Er3+ ions to the host material. The PL from the Er3+ ions hosted in the crystalline phase was distinguished only when the glass-ceramic was excited by the 1480 nm pulsed laser. The excitation pathways responsible for the green and red PL bands are discussed to explain the differences between the spectra observed under continuous-wave and pulsed excitation. © 2013 American Institute of Physics.

The impact of hydrofluoric acid etching followed by unfilled resin on the biaxial strength of a glass-ceramic

Objectives: To evaluate the null hypotheses that hydrofluoric (HF) acid etching time would neither decrease the biaxial flexural strength of a glass-based veneering ceramic nor enhance it after silane and unfilled resin (UR) applications. Methods: Disc-shaped IPS e.max ZirPress specimens were allocated into 12 groups: G1-control (no-etching), G2-30 s, G3-60 s, G4-90 s, G5-120 s, G6-60 s + 60 s. Groups (G7-G12) were treated in the same fashion as G1-G6, but followed by silane and UR applications. Surface morphology and roughness (Ra and Rq) of the ceramics were assessed by means of scanning electron microscopy (SEM) and profilometry, respectively. Flexural strength was determined by biaxial testing. Data were analyzed by two-way ANOVA and the Sidak test (α = 0.05). Weibull statistics were estimated and finite element analysis (FEA) was carried out to verify the stress concentration end areas of fracture. Results: The interaction (etching time vs. surface treatment) was significant for Ra (p = 0.008) and Rq (0.0075). Resin-treated groups presented significantly lower Ra and Rq than non-treated groups, except for the 60 s group (p < 0.005). SEM revealed that etching affected the ceramic microstructure and that the UR was able to penetrate into the irregularities. A significant effect of etching time (p = 0.029) on flexural strength was seen. G7-G12 presented higher strength than G1-G6 (p < 0.0001). None of experimental groups failed to show 95% confidence intervals of σ 0 and m overlapped. FEA showed lower stress concentration after resin treatment. Significance: HF acid etching time did not show a damaging effect on the ceramic flexural strength. Moreover, the flexural strength could be enhanced after UR treatment. © 2013 Academy of Dental Materials.

Valorization of sugarcane bagasse ash: Producing glass-ceramic materials

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hard machining, glaze firing and hydrofluoric acid etching: Do these procedures affect the flexural strength of a leucite glass-ceramic?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Characterization of a wollastonite glass-ceramic material prepared using sugar cane bagasse ash (SCBA) as one of the raw materials

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Heat treatment of pre-hydrolyzed silane increases adhesion of phosphate monomer-based resin cement to glass ceramic

This study evaluated the influence of different forms of heat treatment on a pre-hydrolyzed silane to improve the adhesion of phosphate monomer-based (MDP) resin cement to glass ceramic. Resin and feldspathic ceramic blocks (n=48, n=6 for bond test, n=2 for microscopy) were randomly divided into 6 groups and subject to surface treatments: G1: Hydrofluoric acid (HF) 9.6% for 20 s + Silane + MDP resin cement (Panavia F); G2: HF 9.6% for 20 s + Silane + Heat Treatment (oven) + Panavia F; G3: Silane + Heat Treatment (oven) + Panavia F; G4: HF 9.6% for 20 s + Silane + Heat Treatment (hot air) + Panavia F; G5: Silane + Heat Treatment (hot air) + Panavia F; G6: Silane + Panavia F. Microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using stereomicroscope and scanning electron microscope (SEM) to categorize the failure types. Data were analyzed statistically using two-way test ANOVA and Tukey's test (=0.05). Heat treatment of the silane containing MDP, with prior etching with HF (G2: 13.15 ± 0.89a; G4: 12.58 ± 1.03a) presented significantly higher bond strength values than the control group (G1: 9.16 ± 0.64b). The groups without prior etching (G3: 10.47 ± 0.70b; G5: 9.47 ± 0.32b) showed statistically similar bond strength values between them and the control group (G1). The silane application without prior etching and heat treatment resulted in the lowest mean bond strength (G6: 8.05 ± 0.37c). SEM analysis showed predominantly adhesive failures and EDS analysis showed common elements of spectra (Si, Na, Al, K, O, C) characterizing the microstructure of the glass-ceramic studied. Heat treatment of the pre-hydrolyzed silane containing MDP in an oven at 100 °C for 2 min or with hot air application at 50 ± 5 ºC for 1 min, was effective in increasing the bond strength values between the ceramic and resin cement containing MDP.

Color tunability of intense upconversion emission from Er3+-Yb3+ co-doped SiO2-Ta2O5 glass ceramic planar waveguides

This work reports on the infrared-to-visible CW frequency upconversion from planar waveguides based on Er3+-Yb3+-doped 100-xSiO(2)-xTa(2)O(5) obtained by a sol-gel process and deposited onto a SiO2-Si substrate by dip-coating. Surface morphology and optical parameters of the planar waveguides were analyzed by atomic force microscopy and the m-line technique. The influence of the composition on the electronic properties of the glass-ceramic films was followed by the band gap ranging from 4.35 to 4.51 eV upon modification of the Ta2O5 content. Intense green and red emissions were detected from the upconversion process for all the samples after excitation at 980 nm. The relative intensities of the emission bands around 550 nm and 665 nm, assigned to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(15/2) transitions, depended on the tantalum oxide content and the power of the laser source at 980 nm. The upconversion dynamics were investigated as a function of the Ta2O5 content and the number of photons involved in each emission process. Based on the upconversion emission spectra and 1931CIE chromaticity diagram, it is shown that color can be tailored by composition and pump power. The glass ceramic films are attractive materials for application in upconversion lasers and near infrared-to-visible upconverters in solar cells.

Oxide thermoelectrics via a glass-ceramic route

Thermoelektrizität beschreibt die reversible Beeinflussung und Wechselwirkung von Elektrizität und Temperatur T in Systemen abseits des thermischen Gleichgewichtes. In diesen führt ein Temperaturgradient entlang eines thermoelektrischen Materials zu einem kontinuierlichen Ungleichgewicht in der Energieverteilung der Ladungsträger. Dies hat einen Diffusionsstrom der energiereichen Ladungsträger zum kalten Ende und der energiearmen Ladungsträger zum heißen Ende zur Folge. Da in offenen Stromkreisen kein Strom fließt, wird ein Ungleichgewicht der Ströme über das Ausbilden eines elektrischen Feldes kompensiert. Die dadurch entstehende Spannung wird als Seebeck Spannung bezeichnet. Über einen geeigneten Verbraucher, folgend aus dem Ohm'schen Gesetz, kann nun ein Strom fließen und elektrische Energie gewonnen werden. Den umgekehrten Fall beschreibt der sogenannte Peltier Effekt, bei dem ein Stromfluss durch zwei unterschiedliche miteinander verbundene Materialien ein Erwärmen oder Abkühlen der Kontaktstelle zur Folge hat. Die Effizienz eines thermoelektrischen Materials kann über die dimensionslose Größe ZT=S^2*sigma/kappa*T charakterisiert werden. Diese setzt sich zusammen aus den materialspezifischen Größen der elektrischen Leitfähigkeit sigma, der thermischen Leitfähigkeit kappa und dem Seebeck Koeffizienten S als Maß der erzeugten Spannung bei gegebener Temperaturdifferenz. Diese Arbeit verfolgt den Ansatz glaskeramische Materialien mit thermoelektrischen Kristallphasen zu synthetisieren, sie strukturell zu charakterisieren und ihre thermoelektrischen Eigenschaften zu messen, um eine Struktur-Eigenschaft Korrelation zu erarbeiten. Hierbei werden im Detail eine elektronenleitende (Hauptphase SrTi_xNb_{1-x}O_3) sowie eine löcherleitende Glaskeramik (Hauptphase Bi_2Sr_2Co_2O_y) untersucht. Unter dem Begriff Glaskeramiken sind teilkristalline Materialien zu verstehen, die aus Glasschmelzen durch gesteuerte Kristallisation hergestellt werden können. Über den Grad der Kristallisation und die Art der ausgeschiedenen Spezies an Kristallen lassen sich die physikalischen Eigenschaften dieser Systeme gezielt beeinflussen. Glaskeramiken bieten, verursacht durch ihre Restglasphase, eine niedrige thermische Leitfähigkeit und die Fermi Energie lässt sich durch Dotierungen in Richtung des Leitungs- oder Valenzbands verschieben. Ebenso besitzen glaskeramische Materialien durch ihre Porenfreiheit verbesserte mechanische Eigenschaften gegenüber Keramiken und sind weniger anfällig für den Einfluss des Sauerstoffpartialdruckes p_{O_2} auf die Parameter. Ein glaskeramisches und ein gemischt keramisch/glaskeramisches thermoelektrisches Modul aus den entwickelten Materialien werden konzipiert, präpariert, kontaktiert und bezüglich ihrer Leistung vermessen.

Immediate shear bond strengths of a composite, a compomer and a glass ionomer to a ceramic substrate.

PURPOSE To determine the best-performing combination of three core buildup materials and three bonding materials based on their bond strength to ceramic blocks in vitro. MATERIALS AND METHODS The materials used for core buildup were a composite (Tetric EvoCeram), a compomer (Compoglass F), and a glass-ionomer cement (Ketac Fil Plus), and for bonding, a three-step etch-and-rinse adhesive (Syntac), a two-step etch-and-rinse adhesive (ExciTE), and a single-step system (RelyX Unicem). Bond strength to ceramic blocks was determined by shear bond strength testing. Fracture behavior was evaluated by scanning electron microscopy. RESULTS The highest adhesive values between buildup and ceramic were obtained using the materials Compoglass F and Syntac, followed by Compoglass F and ExciTE. Among the two other core buildups, Tetric EvoCeram performed better than Ketac Fil Plus, which was independent of the bonding materials. Adhesive fractures were characteristically observed with Syntac and ExciTE, and cohesive fractures were characteristically observed with RelyX Unicem. CONCLUSION These data show that compomers bonded with a multistep adhesive system achieved statistically significantly higher shear bond strength than composites and glass-ionomer cements. Within the limitations inherent to this in vitro study, the use of compomers for core buildup can be recommended.

Arbitration cases between Pittsburg plate glass company and Federation of glass, ceramic and silica sand workers of America - CIO. 1945-1953.

Mode of access: Internet.

Arbitration cases between Federation of Glass, Ceramic and Silica Sand Workers of America-CIO and Mosaic Tile Company, Cambridge Tile Manufacturing Co., Pittsburgh Plate Glass Company, Brickwede Brothers Company, Rohm & Haas Company, Franklin Clay Manufacturing Co.

Cover title.