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CeO2–ZrO2–Al2O3 composite oxides supported palladium catalysts (Pd/CZA) are promising candidates for catalytic oxidation reactions. However, the efficient and stable oxidation of methane over Pd-based catalysts remains a longstanding challenge. Herein, we present a facile strategy to boost the catalytic performance of Pd/CZA through elaborately tuning the phase structure of supports. Calcining supports at relatively high temperatures (1200, 1300 °C) induced the phase transition of alumina (from γ-to α-) and the development of CeO2–ZrO2 solid solution (CZ). The weak interaction between α-Al2O3 and PdO resulted in an improved reducibility of catalysts. Meanwhile, the higher oxygen mobility originated from well-crystallized CZ phase contributed to the reoxidation of Pd to PdO, giving rise to abundant surface active Pd2+ species. Coupled with the hydrophobicity of α-Al2O3, the catalyst prepared with CZA supports calcined at 1300 °C demonstrated an excellent low-temperature activity, astounding stability and greatly enhanced water resistance towards methane combustion.

In this study, yttrium aluminum garnet/yttria-stabilized zirconia (YAG/YSZ) double-ceramic-layer thermal barrier coatings (DCL TBC) and yttria-stabilized zirconia (YSZ) single-ceramic-layer thermal barrier coatings (SCL TBC) were deposited by atmosphere plasma spray (APS) on the Inconel 738 alloy substrate, and isothermal oxidation tests were performed to investigate the formation and growth behavior of thermally grown oxide (TGO). Results showed that the Al2O3 TGO thickness of both TBC groups increased by increasing the isothermal oxidation time，and then slowly decreased with the appearance and growth of the adverse multilayer structure comprising CoCr2O4, (Ni,Co)Al2O4, NiCr2O4, and NiO mixed oxides. However, since the significant inhibition effect of the YAG coating to oxygen ionic diffusion, the mixed oxides appearance time and TGO growth behaviors were delayed in the DCL TBC. As a result, the TGO thickness of the DCL TBC was always smaller than that of the SCL TBC in the entire oxidation process. And the Al2O3 layer thickness proportion in the total TGO of the DCL TBC was greater than or equal to that of the SCL TBC after oxidation for the same period. The results of weight gain showed that compared with the SCL TBC, the parabolic oxidation rate of the DCL TBC was decreased approximately 35%. Consequently, the DCL TBC has better high-temperature oxidation resistance than the SCL TBC.

For the cost-effective fabrication of Na+-β/β"-alumina solid electrolyte, we developed a synthesizing-cum-sintering process as an alternative to the conventional solid-state reaction process. To improve mechanical and electric properties of Na+-β/β"-alumina, we added MnO2 and Ta2O5/YSZ (partially Y2O3-stabilized zirconia, 8.0 wt% fixed) as a dopant to the Na+-β/β"-alumina. For MnO2-doped specimens, the β"-alumina phase fraction, relative sintered density, and ionic conductivity increased when the MnO2 amount changed from 0.0 to 1.0 wt%. The maximum ionic conductivity, i.e., 1.0 × 10−1 S/cm at 350 °C, was achieved with the 1.0 wt% MnO2-doped Na+-β/β"-alumina sintered specimen. For Ta2O5-doped Na+-β/β"-alumina/YSZ composite sintered specimens, ionic conductivity increased when the Ta2O5 amount changed from 0.0 to 0.3 wt%. The 0.3 wt% added Ta2O5-doped Na+-β/β"-alumina/YSZ composite sintered specimen exhibited ionic conductivity as high as 1.1 × 10−1 S/cm at 350 °C.

Ceramic Injection Moulding (CIM) is an advanced powder processing technology launched three decades ago which has become a growing attractive alternative for new technical applications, such as thermal management and wireless charging. Porcelain-type ceramics can allow the introduction of new feedstocks into the CIM market at a competitive cost, in comparison with the conventional alumina and zirconia feedstocks. During the CIM manufacturing process, several factors related to the starting powder characteristics have an influence on the quality and properties of the final components, such as the mixing behaviour and the feedstock flow properties, as well as injection, debinding and sintering parameters. In this work, the viability of three porcelain-based powders to successfully achieve injectable mixtures for CIM is described. The mixing behaviour and the feedstocks flow behaviour as a function of its solids loading is evaluated. In this way, the ideal attributes for a CIM porcelain powder are discussed, studying the first process stages through to the production of a sintered component by injection moulding. Finally, density, hardness, bending strength and microstructural properties of the selected porcelain are investigated and a cost-efficient ceramic feedstock is suggested for aesthetic and electrical applications. Resumen: El moldeo por inyección de cerámica (en inglés, Ceramic Injection Moulding [CIM]) es una tecnología avanzada de conformado de polvos establecida hace tres décadas que recientemente se ha convertido en una atractiva alternativa para nuevas aplicaciones avanzadas, como la gestión térmica y la recarga inalámbrica de dispositivos. Las cerámicas de tipo porcelana permiten la introducción de nuevos feedstocks en el mercado CIM a precios más bajos en comparación con los tradicionales de alúmina y zircona. Existen varios factores que influyen en la calidad y las propiedades de los componentes finales en el procesado CIM y que están relacionados con las características del polvo de partida, como son el comportamiento durante el mezclado y la fluidez del feedstock, así como los parámetros de inyección, eliminación y sinterización. En este trabajo se describe la viabilidad de tres porcelanas para obtener mezclas inyectables que puedan procesarse con éxito mediante CIM. Se muestra la estabilización del par de torsión durante el proceso de mezclado, así como la fluidez de los diferentes feedstocks en función de la carga cerámica. Asimismo, se discuten las cualidades que idealmente se buscan en un polvo para ser procesados mediante CIM. Finalmente, se muestran los resultados obtenidos de densidad, propiedades microestructurales y propiedades mecánicas (dureza y resistencia a la flexión) de la porcelana seleccionada, y se demuestra que la mezcla inyectable diseñada a precio competitivo puede utilizarse para aplicaciones estéticas y eléctricas en futuros trabajos.

The fabrication of porous silicon carbide (SiC) ceramics prepared by existing reaction bonding technology requires high-temperature sintering beyond 1400 °C. We used low-cost industrial grade water glass and zirconia as sintering aids to prepare porous SiC ceramic filters to reduce the sintering temperature while improving the commerciality. Additionally, we investigated the effects of different sintering temperatures and the addition of water glass on the samples. Loading water glass and zirconia reduced the sintering temperature to 600 °C. The additive-loaded ceramic filter sintered at 600 °C exhibited an average pore size of 0.58 μm, a porosity of 47.4%, a bending strength reaching 56 MPa, a pure water permeance exceeding 4800 L m−2h−1bar−1, and good acid corrosion resistance. In addition, the SiC filter prepared at 1000 °C showed good chemical resistance and an average pore size of 0.75 μm as well as mechanical strength and pure water permeance of over 80 MPa and 6294 L m−2h−1bar−1, respectively. The low-cost, high-performance porous SiC ceramic filter exhibits broad commercial application prospects in water treatment.

Monoclinic zirconia (ZrO2) whiskers were made via the molten salt method using zirconyl chloride octahydrate (ZrOCl2 ? 8H2O) as zirconium source, potassium chloride (KCl) as molten salt and lithium fluoride (LiF) as a mineraliser. DSC-TG, XRD, FE-SEM, Raman and TEM were performed to study the effects of heat treatment temperature, holding time and heating rate on the synthesis of zirconia whiskers. The results indicate that zirconia whiskers with diameters of 50-80 nm and aspect ratios of 10-30 can be obtained by heating the precursor at slow rate (3?C/min) to 718?C for 1 h and then at faster rate (7?C/min) to 950?C for 3 h. The whiskers have a smooth surface and grow in [001] direction. The key to the ZrO2 whiskers growth is the controlled dissolution and precipitation of the ZrO2 in a LiF-KCl molten salt solution environment.

PURPOSE To analyze the load to failure of different CAD/CAM high-density polymers (HDPs) and zirconia when titanium (Ti) bases were included in a cantilevered situation. MATERIALS AND METHODS Five specimens were fabricated from five different CAD/CAM polymethyl methacrylate (PMMA) HDPs (Copratemp [CT]; Tempo-CAD [TC]; TD Dental [TD]; M-PM Disc-Pink [MPM]; M-PM Disc-White [MPMW]), and five specimens were prepared from a 3Y-TZP zirconia (FireZr [FZR]) (control). Ti bases (D Master Dental Implants) were cemented onto the specimens (8 mm [thickness] × 7 mm [width] × 30 mm [length]). Each specimen was fixated using a clamp for a cantilever loading distance of 10 mm. The load was applied on the cantilever until failure, and the maximum load to failure values (N) were analyzed by using analysis of variance (GLIMMIX procedure) with a lognormal error distribution in addition to the restricted maximum likelihood estimation method to eliminate the need for equality of variances and Tukey Honest Significant Difference (α = .05). RESULTS Differences among load-to-failure values of HDPs were not significant (P > .05). However, zirconia had significantly higher load-to-failure values than HDPs (P < .001). The behavior of HDPs and zirconia under loading was different in terms of displacement. HDPs showed weaker but more ductile behavior than zirconia, which is stronger, but more brittle. CONCLUSION Tested brands of HDPs performed similarly under loading. Zirconia with a Ti base showed higher strength compared to all tested HDPs with a Ti base. The loads that fractured the specimens with Ti bases were close to the maximum occlusal bite forces recorded in previous clinical studies.

In the present work the solid-state synthesis of phase-pure barium zirconate (BaZrO3) using barium carbonate and monoclinic zirconia as powder raw materials is investigated. Due to the high evaporation tendency of BaO, special attention is paid to the thermogravimetric behaviour of stoichiometric mixtures of BaCO3 and ZrO2, namely without sintering aids. DSC/TG measurements of the powder mixtures were conducted to assess the synthesis reaction using heating rates of 1, 3 and 10 K min−1. In addition to the investigations of the thermogravimetric behaviour in dependence of different heating rates, the influence of synthesis temperature and ceramic carrier grains was examined on pressed specimens of 50 mm in diameter. Moreover, the influence of three different partial pressure relations resulting from the decarbonisation reaction and the assumed BaO evaporation was investigated. It was found that a synthesis temperature of 1200 °C and a heating rate of 1 K min−1 resulted in the least pronounced mass loss and mass loss rate, respectively. XRD analyses revealed phase-purity for specimens of assumed low BaO evaporation. Thus, optimum thermal treatment conditions were identified for the BaZrO3 synthesis that can be applied to the production of phase-pure material for e.g. the refractory industry.

(1) Background: to propose a new approach for crown veneers, with the use of an aesthetic porcelain coating, only in part of the zirconia infrastructure, and to analyze its biomechanical behavior to minimize chipping failures. (2) Methods: a maxillary molar was modeled using CAD software, preparing for traditional crowns and veneer crowns with various lengths. Five groups were formed: M—control group (monolithic crown of ultra-translucent zirconia), B—conventional (bilayer crown of ultra-translucent zirconia and ceramic covering), V—veneer (ultra-translucent zirconia crown with reduction only in the buccal and application of covering ceramics), V1—ultra-translucent zirconia crown with buccal reduction and 1 mm occlusal extension for covering ceramic application), V1.5—ultra-translucent zirconia crown with buccal reduction and 1.5 mm occlusal extension for application of covering ceramics. A load of 600 N was performed axially to a fossa bottom to simulate parafunction, and 300 N to the cusp tip to obtain the maximum principal stress results. (3) Results: group B showed a higher stress concentration in the occlusal region of the restorations, while the other groups absorbed the stress and dissipated it throughout the crown, presenting a higher stress concentration in the interface region with the tooth. (4) Conclusion: the highly translucent zirconia ceramic only associated with buccal covering ceramic could add aesthetic gain and rigidity to the system and could be a good option to restore maxillary molars in patients who do not have parafunction.

Aggregative stability of a polydisperse zirconium oxide sol with average sizes of primary particles and aggregates equal to 24 and 95 nm, respectively, has been studied within a wide range of sodium chloride concentrations (3 × 10−3–1 M) by turbidimetry and dynamic light scattering. The experiments have been performed at pH 4.2 and 5.6, when sol particles are positively charged, and at pH 11, when they are negatively charged. The regions of weak and intense slow coagulation, as well as the region of fast coagulation, have been determined and characterized. It has been shown that, in most cases, the thresholds of the intense slow coagulation determined from the concentration dependences of the optical density and the average particle size coincide with each other within the experiment error. Assumptions have been brought out on the coagulation mechanism and its changes upon the passages between the coagulation regions, as well as on the role of the ratios between the particle sizes of separate fractions and their amounts in the sol.

Background: Nowadays, the esthetics demand is continuously increasing; therefore, metal-free materials are widely used, like a zirconia-based ceramic, which is conveniently fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) system for restorations from single to full mouth rehabilitation. Objective: This study evaluated the effect of pre-curing pressure on the shear bond strength of zirconia to the resin cement. Methods: A total of sixty-three sandblasted cylindrical zirconia mounted in autopolymerizing resin were randomly assigned to three groups; Group 1: no treatment (control), Group 2: negative pressure, and Group 3: positive pressure to resin cement after resin cement application and resin composite columns bonded to zirconia. Thirty-three of the samples were stored in distilled water at 37 °C for 24 hr before the shear bond strength test for thirty samples and three samples were cross-sectionally cut for interfacial observation with FESEM. Another thirty samples were thermocycled for 5,000 cycles in distilled water at 5°C to 55 °C before testing. The shear bond strength and failure mode were evaluated. Examination of the bonding interface was also done. Results: The results were analyzed using two-way ANOVA. The means of shear bond strength of non-thermocycle of the control group were 8.01 ±1.74 MPa, 9.10 ±1.90 MPa, and 9.14 ±2.58 MPa, whereas that of thermocycle group were 5.71 ±0.84 MPa, 5.53 ±0.68 MPa, and 5.68 ±0.77 MPa in zero pressure group, negative pressure group, and positive pressure group, respectively. It showed no statistically significant differences in shear bond strength in all pressure groups (p > 0.05). The pre-curing pressure did not influence the shear bond strength of the zirconia and resin cement. Conclusion: There was no difference in the shear bond strength between the pressure groups and the no treatment control group. The positive and negative pressure did not influence the shear bond strength of the zirconia and resin cement.

STATEMENT OF PROBLEM Whether additively produced zirconia could overcome problems with conventional computer-aided design and computer-aided manufacture (CAD-CAM) such as milling inaccuracies and provide accurate occlusal veneers is unclear. PURPOSE The purpose of this in vitro study was to compare the marginal and internal fit of 3D-printed zirconia occlusal veneers with CAD-CAM-fabricated zirconia or heat-pressed lithium disilicate ceramic (LS2) restorations on molars. MATERIAL AND METHODS The occlusal enamel in 60 extracted human molars was removed, with the preparation extending into dentin. Occlusal veneers at a thickness of 0.5 mm were designed and manufactured according to their group allocation: 3DP, 3D-printed zirconia; CAM, milled zirconia; and HPR, heat-pressed LS2. The prepared teeth and restorations were scanned and superimposed, and the marginal and internal adaptation were measured 2- and 3-dimensionally; the production accuracy (trueness) was also measured. The comparisons of the group medians were performed with nonparametric methods and a pairwise group comparison (α=.05). RESULTS Three-dimensionally printed zirconia revealed median outcomes of 95 μm (margin), 252 μm (cusp), 305 μm (fossa), and 184 μm (3D internal adaptation). CAM showed median values of 65 μm (margin), 128 μm (cusp), 203 μm (fossa), and 120 μm (3D internal adaptation). The respective values for the group HPR were 118 μm (margin), 251 μm (cusp), 409 μm (fossa), and 180 μm (3D internal adaptation). Significant differences (P

Amaç: Dental restorasyonların marjinal uyumu, uzun vadeli başarı için hayati bir faktördür. Yüksek sıcaklıklarda birden fazla sayıda fırınlamayı içeren zirkonyum veneerleme işleminin, zirkonya altyapıların marjinal uyumunu etkilediği gösterilmiştir. Bu çalışmanın amacı, farklı prosedürlerle sinterlenmiş zirkonya iskeletlerin veneerleme pişirimleri sırasındaki boyutsal ve marjinal boşluk değişimlerini gözlemlemektir.Gereç ve Yöntemler: 30 Y-TZP ((inCoris ZI, Sirona, Bensheim, Almanya) kuron altyapısı 8 saat, 2 saat ve 10 dakikalık üç farklı süre ile sinterlendi. Ölçüm mikroskobu ile referans noktalarına dayalı oklüzal ve bukkal boyutsal ölçümler yapıldı. Pişirme işleminin etkisini gözlemlemek için porselen malzemesi uygulanmadan veneer pişirmeleri yapıldı. Tüm boyutsal ve marjinal boşluk ölçümleri tekrarlandı ve veneer fırınlamasından önce ve sonra alınan veriler tek yönlü ANOVA ve eşleştirilmiş t testi ile analiz edildi.Bulgular: Üç grubun sinterleme büzülmesi arasında önemli bir farklılık gözlenmedi. Marjinal boşluklar tüm gruplarda veneer pişirmelerinden sonra azaldı ve azalma 2 saat ve 10 dakikalık sinterleme gruplarında anlamlıydı (p, Background: The marginal fit of dental restorations is a vital factor for long-term success. The veneering process of zirconia, which involves multiple firings at high temperatures, has shown to affect the marginal fit of zirconia cores. The aim of this study is to observe dimensional and marginal gap changes during veneer firing of zirconia frameworks sintered with different procedures.Methods: 30 Y-TZP ((inCoris ZI, Sirona, Bensheim, Germany) crown frameworks sintered with three different durations of 8 hours, 2 hours and 10 minutes. Occlusal and buccal dimensional measurements based on reference points measured with toolmaker’s microscope. Frameworks subjected to veneer firings without application of veneering material to observe the effect of firing process only. All dimensional and marginal gap measurements were repeated and after veneer firings. Data were analysed with one-way ANOVA and paired t test.Results: No significant differences observed between the sintering shrinkage of three groups. Marginal gaps decreased after veneer firings for all groups and the decrease was significant for 2 hour and 10-minute sintering groups (p

The aim of this study is the investigation of the effect of blade designs used in the universal testing machine on the shear bond strength values. Three different zirconia framework ceramics (Zirkonzahn Translucent, Upcera Super Translucent, Rainbow Trans) and veneering ceramics suggested by their manufacturers (Zirkonzahn ICE Porcelain, Cerabien ZR Porcelain, Rainbow Porcelain) were subjected to shear bond strength tests with three different blade designs. Metal-ceramic (EOS Cobalt Chrome SP2 — GC Initial Porcelain) was used as a control group. A total of 90 samples (n = 10) for experimental group with zirconia framework and 30 samples of control group (n = 10) were prepared. Shear bond strength tests were performed with wire-loop design in the first group, notched-rod in the second group, and knife-edge chisel designs in the third group. Statistical analysis of the data was made by the Kruskal–Wallis test and followed by Conover’s multiple comparison test. When the test results made with different blade designs were examined, no significant difference was found for zirconia samples. In the control group, a statistically significant difference was found between different blade designs. It was observed that the wire-loop group had significantly higher shear bond strength values compared to the notched-rod and knife-edge chisel groups. Used blade designs should be standardized in order to be able to evaluate the materials and methods used in the studies in the literature.

Objective: This study aims to analyze structural strength features (such as deformation and stress distributions) of polyether ether ketone (PEEK), glass fiber and zirconia post-core systems utilized in maxillary central incisor roots by means of finite element analysis (FEA). Material and Method: The main geometry of maxillary central incisor considered in this study was obtained using an intraoral scanner. Other sub-components were modelled in a parametric computer aided design software based on the data obtained from the literature. Glass fiber, PEEK and zirconia were defined as post materials. 100 N force was applied with 45° angle on the palatal surface of veneered tooth in the FEA set up. The FEA was solved with linear material model and static linear loading assumptions through a commercial FEA code. Visuals and numerical results related to equivalent stress (Von Mises) and deformation distributions were interpreted. Results: Maximum equivalent stress value of 32.76 MPa was calculated at the PEEK post-core. The maximum values for glass fiber and zirconia posts were 0.80 MPa and 21.17 MPa, respectively. Maximum equivalent stress values at the tooth roots in the glass fiber, zirconia and PEEK posts were 72.79 MPa, 69.01 MPa and 58.22 MPa respectively. Conclusion: The stress magnitude experienced at the PEEK post-cores on the root was lower than glass fiber post and zirconia post. Regarding to this, although, it may be concluded that PEEK may reduce the complications that require tooth extraction in clinical practice, further researches are suggested including clinical trials.

The green biogenic synthesis of nanoparticles using natural sources is always eco-friendly and attractive. The current study has focused on the production of ZrO2 nanoparticles using the aqueous leaf extract of Laurus nobilis (bay leaf). The structural and morphological properties of ZrO2 nanoparticles were investigated through UV–visible absorption spectrophotometer, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and dynamic light scattering (DLS). The characterization techniques confirmed the formation of ZrO2 nanoparticles with the diameter from 20 to 100 nm. FTIR spectra also demonstrated the formation of ZrO2 in the crystalline phase. The narrow and edged peaks obtained from XRD symbolized a notable increase in the crystalline index of the obtained zirconium nanoparticles. The SEM micrographs revealed the morphology as spherical shaped. Various concentrations of the obtained zirconium nanoparticles were tested to check their inhibitory action against certain microorganisms such as Gram-positive bacteria, Gram-negative bacteria and a fungus. The inhibitory actions against the tested microorganisms were directly proportional to the concentration of the obtained zirconium nanoparticles. Consequently, the dispersion properties of ZrO2 nanoparticles in the aqueous solution increased considerably, which might have contributed to the antimicrobial activity. Hence, the synthesized ZrO2 nanoparticles of L. nobilis can serve as an antimicrobial agent, which may play a vital role in medical industry.

Made available in DSpace on 2022-04-28T19:43:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 National Institute of Dental and Craniofacial Research National Institutes of Health Office of Extramural Research, National Institutes of Health Office of Research Infrastructure Programs, National Institutes of Health Objective: To investigate the influence of different finishing/polishing techniques and in situ aging on the flexural strength (σ), surface roughness, and Candida albicans adherence of 5 mol% yttria-stabilized zirconia (ultratranslucent zirconia). Materials and methods: A total of 120 zirconia bars (Prettau Anterior, Zirkonzahn) with dimensions of 8 × 2 × 0.5 mm were divided into 8 groups (n = 15) according to two factors: “in situ aging” (non-aged and aged (A)) and “finishing/polishing” (control (C), diamond rubber polishing (R), coarse grit diamond bur abrasion (B), and coarse grit diamond bur abrasion + diamond rubber polishing (BR)). Half of the samples from each group were subjected to a 60-day in situ aging by fixing the bars into cavities prepared in the posterior region of the base of complete or partial dentures of 15 patients. The samples were then subjected to the mini flexural (σ) test (1 mm/min). A total of 40 zirconia blocks (5 × 5 × 2 mm) were prepared and subjected to roughness (Ra) analyses and fungal adherence and complementary analyses (X-ray diffraction (XRD) and scanning electron microscopy (SEM)). The data of mean σ (MPa) and roughness Ra (μm) were statistically analyzed by two-way and one-way ANOVA, respectively, and Tukey’s test. The Weibull analysis was performed for σ data. The fungal adhesion (Log CFU/mL) data were analyzed by Kruskal–Wallis tests. Results: For flexural resistance, the “finishing/polishing” factor was statistically significant (P = 0.0001); however, the “in situ aging” factor (P = 0.4458) was not significant. The non-aged (507.3 ± 115.7 MPa) and aged (487.6 ± 118.4 MPa) rubber polishing groups exhibited higher mean σ than the other techniques. The non-aged (260.2 ± 43.3 MPa) and aged (270.1 ± 48.8 MPa) bur abrasion groups presented lower σ. The coarse-grit diamond bur abrasion group (1.82 ± 0.61 µm) presented the highest roughness value (P = 0.001). Cell adhesion was not different among groups (P = 0.053). Group B presented the most irregular surface and the highest roughness Ra of 0.61 m. Conclusions: The finishing of ultratranslucent zirconia might be preferably done with a diamond rubber polisher. Moreover, the protocols used did not interfere with Candida albicans adhesion. Clinical relevance: Coarse-grit diamond burs might be avoided for finishing ultratranslucent monolithic zirconia, which might be preferably performed with a diamond rubber polisher. Health Science Center Department of Dentistry Division of Prosthodontics Federal University of Rio Grande Do Norte (UFRN), Avenida Senador Salgado Filho, nº 1787, Lagoa Nova, RN Department of Dentistry University of Pernambuco (UPE), Av. Governador Agamenon Magalhães, S/N- Santo Amaro, PE Department of Dentistry Federal University of Paraíba (UFPB), Campus I - Cidade Universitária, PB Department of Dental Materials and Prosthodontics Institute of Science and Technology Univ Estadual Paulista - UNESP, Av. Eng. Francisco Jose Longo, 777, SP School of Dental Medicine Department of Preventive and Restorative Sciences University of Pennsylvania, 240 S. 40th Street Department of Dental Materials and Prosthodontics Institute of Science and Technology Univ Estadual Paulista - UNESP, Av. Eng. Francisco Jose Longo, 777, SP National Institute of Dental and Craniofacial Research: R01 DE026279 National Institutes of Health: R01 DE026772 Office of Extramural Research, National Institutes of Health: R01 DE026772 Office of Research Infrastructure Programs, National Institutes of Health: R01 DE026772

To assess the efficacy of experimental cleaners containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) on the saliva decontamination of ceramic and their influence in restoring zirconia’s adherence to resin cement. Four hundred sixty alumina-blasted zirconia specimens were categorized into saliva-contaminated and uncontaminated groups which were treated with ceramic primer (P), experimental cleaner 1 (C1), C1 followed by P (C1P), experimental cleaner 2 (C2), and C2 followed by P (C2P). Stainless-steel rods were then attached to the specimens using PanaviaV5 cement (Kuraray Noritake Dental; Tokyo, Japan). Tensile bond strength (TBS) test was performed after 24 h and 5000 thermocycling processes. X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurement of the specimen were performed. The TBS data were analyzed by Weibull analysis and three-way ANOVA. Contact angle data were analyzed by two-way ANOVA (α = 0.05). C2P groups showed the highest TBS in all conditions among tested groups. Saliva contamination led to a significant reduction of TBS in primer- and cleaner-treated groups, with no significant impact on C2P. Adhesive failure was predominant in contaminated groups except with the C1P and C2P groups. XPS revealed that a nitrogen peak was observed on contaminated groups but not in primed groups. The contact angle was significantly affected by saliva contamination, the cleaners, and/or ceramic primer usage (p

In the present work, zirconia-based ceramics incorporated with TiO2 (titania) were produced and characterized as candidate material for use as thermal barrier coating (TBC). Zirconia was stabilized in the tetragonal metastable phase from the addition of 24 wt.% of MgO (magnesia). Alternative materials, such as these, have been studied worldwide in order to prospect candidates for TBC application with improved temperature behavior. Titania was added to the matrix of ZrO2.24MgO in the proportions of 0, 7.5, 15, and 22.5 wt.%. The compacted samples were sintered for 24 h in thermal cycles at 1250 °C. Powder characteristics were evaluated by scanning electron microscopy and light scattering technique. The phase identification of raw materials and the sintered ceramics was investigated by powder X-ray diffractometry. The microstructural characterization of the sintered ceramics was performed by scanning electron microscopy and energy dispersive X-ray spectroscopy, physical indices were characterized by Archimedes’ method and the mechanical behavior evaluated by Vickers microhardness. The results indicate a direct influence of the TiO2 contents (up to 7.5 wt.%) in the improvement of the verified properties.

In this work, the influence of La2O3 on microstructure and mechanical properties of 5 wt% alumina dispersed in 2.3 mol% yttria-stabilized zirconia was investigated, with the aim of optimizing flexural strength and fracture toughness by changing the amount of La2O3. The alumina-dispersed zirconia with different La2O3 contents (0.4, 0.8, 1.2 wt%) were prepared by sintering at 1500 °C for 2 h in air. Structural examinations were performed using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). Mechanical properties of the composites were determined as hardness by conducting Vickers indentation tests, flexural strength by 3-point bending method, and fracture toughness by SEVNB method. Addition of La2O3 had influences on the phase composition by forming long rod-shaped LaAl11O18, which consumed alumina and then increased the fracture toughness by increasing the volume of phase transformation of t-ZrO2. But excess La3+ in zirconia grains would form solid solution and decreased fracture toughness by suppressing phase transformation in t-ZrO2. The composite with 0.8 wt% La2O3 addition was found to be an optimum combination between flexural strength and fracture toughness. The obtained flexural strength and fracture toughness were 947 ± 55 MPa and 6.5 ± 0.1 MPa m1/2, respectively.

Clinical oral investigations (2021). doi:10.1007/s00784-021-04077-2, Published by Springer, Heidelberg

Monolithic self-glazed zirconia is a new type of biomimetic zirconia that has been successfully used as crown and bridge restorations in the anterior and posterior regions. It exhibits excellent bi...

Objectives The aim of this study was to evaluate using finite element analysis (FEA), the stress distribution in prostheses (lithium disilicate crowns) on monotype zirconia implants with and without cantilever in the anterior region of the maxilla. Materials and Methods From a virtual reconstruction of bone model of the toothed maxilla from a computed tomography, three models (groups) were created: Zr (11–21)—implants placed in the area of 11 and 21 with cantilever; Zr (12–22)—implants placed in the area of 12 and 22 without cantilever; and Zr (11–22)—implants intercalated placed in the area of 11 and 22. In all models, monotype zirconia implant (4.1 × 12.0 mm) was used in single-body configuration. Lithium disilicate crowns were designed on the implants and pontics for all groups. A 150-N load was applied to the prostheses. The materials used were considered isotropic, homogeneous, and linearly elastic. FEA was performed to evaluate the maximum (tensile) and minimum (compressive) principal stresses in the implant, crowns, and bone tissue. Data were analyzed qualitatively and quantitatively. Results For all groups, the highest maximum principal stress occurred in the palatal cervical area of the implant, with the high values for the Zr (12–22) group and the low values for the Zr (11–21) group. The maximum principal stress was concentrated in the cervical palatal area of the crown, with the Zr (11–21) group presented the highest values and the Zr (12–22) group showed the lowest values. In the bone tissue all the groups presented similar values of maximum and minimal principal stress, with the palatal (maximum principal) and vestibular (minimum principal) close to the cervical of the implants the area with the highest concentration of stresses. Conclusions The position of monotype zirconia implant did not interfere in the bone tissue stress, and the implants placed in the 11–21 present lower stress in implants and higher in the crown. The cantilever does not increase the stress in the implants, crown, and bone tissue.

To examine the optical properties of a dental restorative material manufactured from lithium aluminosilicate ceramic and reinforced with lithium disilicate. Translucency and the optical effects of various supporting materials on color were the primary focus.Five 10 × 10 mm samples were prepared in thicknesses of 0.5, 1.0, 1.5, and 2.0 mm of both high translucency (HT) and low translucency (LT) versions of the material in shade A3. A spectrophotometer was used to measure the illuminance of the samples with black and white backings in order to calculate contrast ratio (CR) and relative translucency parameter (RTP). A baseline relationship between translucency and material thickness was examined and the effects of composite, titanium, and zirconia abutments on color change were studied.No significant findings were identified for RTP or CR between the HT and LT material, regardless of the material thickness (p = 0.39, p = 0.14, respectively). Regardless of material thickness (HT vs. LT), translucencies (RTP and CR) were significantly different with composite, titanium, and zirconia backings compared to baseline values (p 0.0001). Titanium had the most significant decrease in translucency compared to composite and zirconia. There was no difference in ΔE00 between the HT and LT materials (p 0.05) regardless of the backing. Titanium had the most significant effect on color of both materials followed by composite then zirconia (p 0.0001).There is not a clinically significant difference in translucency between the high translucency and low translucency materials. Only zirconia supporting structures produced changes in color that are clinically acceptable.Understanding the optical properties of glass-ceramic restorative materials aids providers in selecting appropriate materials for optimum esthetic outcomes. The lithium-aluminosilicate reinforced with lithium disilicate material does a poor job masking supporting structures and resisting color change.

Polymer nanocomposite coatings have attracted great interest in the anticorrosion fields due to their excellent properties. Nanofillers are necessary to achieve high anticorrosion performance of the polymer coating. Herein, we report a wet-chemical template strategy to prepare large-size ZrO2 nanosheets, in which the Zr4+ ions are anchored on the surface of a graphene oxide template via electrostatic adsorption, followed by a thermal treatment process to remove graphene. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images show that the size and thickness of as-prepared ZrO2 nanosheets are more than 2 μm and ~ 4.5 nm, respectively. The micron-scale ultrathin two-dimension (2D) ZrO2 nanosheets, for the first time, are utilized as the anticorrosive fillers in the epoxy coating to reduce the porosity, consequently promoting the gas and water barrier properties of the composite coating. The polymer coating containing 1.0 wt% ZrO2 nanosheets shows a high initial impedance (89.1 GΩ·cm2) that can protect the metal substrate from being corroded during long-term immersion (60 days), which is better than that of the reduced graphene oxide (rGO)-incorporated coating and the ZrO2 nanoparticles-incorporated coating. This work offers valuable insights into the design and preparation of novel and efficient 2D electric-inert nanofillers for anticorrosion coatings.

PURPOSE This study aimed to investigate the Vickers Hardness Number (VHN) of light- and dual cured resin cements cured through monolithic zirconia specimens (VITA YZ) of various translucencies: translucent (T); high translucent (HT); super translucent (ST); and extra translucent (XT) at 0, 24, and 48 h after curing. MATERIALS AND METHODS Four zirconia specimens from each translucency were prepared. Two light-cured resin cements (Variolink N LC; VL and RelyX Veneer; RL) and two dual-cured resin cements (Variolink N DC; VD and RelyX U200; RD) were used. The cement was mixed and loaded in a mold and cured for 20 s through the zirconia specimen. The upper surface of cements was tested for VHN using a microhardness tester at 0, 24, and 48 h after curing. The VHN were analyzed using two-way repeated, Brown-Forsythe ANOVA with Games Howell post-hoc analysis and independent t-tests (P < .05). RESULTS All cements showed significantly higher VHN from 0 h to 24 h (P < .001). At 48 h, the VHN of light-cured cements were significantly lower when cured under the T groups than under XT groups (P = .001 in VL, P = .014 in RL). At each post curing time of each translucency, VD showed higher VHN than VL (P < .05), and RD also showed higher VHN than RL (P < .05). CONCLUSION The translucency of zirconia has an effect on the VHN for light-cured resin cements, but has no effect on dual-cured resin cements. Dual-cured resin cement exhibited higher VHN than the light-cured resin cement from the same manufacturer. All resin cements showed significantly higher VHN from 0 h to 24 h.

Carbon species incorporation and carbon deposits are common in the manufacture process and application of yttria-stabilized zirconia (YSZ) ceramics, while the potential corrosion induced by the resultant carburization is unclear. The 3YSZ hollow fiber membranes were prepared by wet spinning method. A sintering procedure at 1300–1450 °C under 0.02 MPa oxygen partial pressure, and thereafter an oxidation treatment at 800 °C were applied to investigate the carbothermal reaction and carburization corrosion mechanism. It was found that the trace carbon species of 1.0–2.2 mol% derived from polymeric precursors triggered the carburizing strengthening of porous YSZ membranes without sacrificing porosity and deformability. However, the carburization corrosion also occurred at the mild oxidation treatment, resulting in deterioration in bending strength and integrated structure converting into fine grains. Raman spectra, XPS bands and HR-TEM images confirmed that the in-situ synthesized ZrCxOy oxidized into monoclinic ZrO2, and micro-cracking formed along grain boundaries, which led to substantial mechanical strength loss.

This paper reports the synergistic effect of the sol and intermediate layer on the performance of yttria-stabilized zirconia (YSZ) nanofiltration (NF) membranes. We have focused on the characterization of the microstructure, pure water permeance, and molecular weight cut-off (MWCO) of the NF membranes derived from zirconia sols of different precursor concentrations on two types of supported ZrO2 ultrafiltration (UF) membranes. We found that the performance of YSZ membranes strongly depends on the sol concentration and the pore size of the intermediate layer. In addition, YSZ gel membrane formation was found to follow the filtration process. Therefore, it is essential to maintain the compatibility between the sol and intermediate layer to fabricate high-performance NF membranes. A crack-free thin YSZ layer with an MWCO of 816 Da (pore size: 1.4 nm) and a water permeance of 25 L m-2 h-1 bar-1 was fabricated using a precursor concentration of 0.03 mol/L, on ZrO2 UF membrane with a pore size of 5.5 nm. The YSZ NF membrane exhibited a relatively high retention rate towards MgCl2 (71%), whereas a lower retention rate was observed for NaCl (35%).

Background. Interfacial failures at the cement‒restoration interface highlights the importance of effective surface treatment with no adverse effect on the zirconia’s mechanical properties. This study aimed to determine the effect of different surface treatments on dental graded zirconia’s surface roughness and certain mechanical properties. Methods. Forty sintered zirconia specimens were randomly divided into four groups (n=10): control (no surface treatment), sandblasting (SA), grinding with diamond bur (GB), and Er,Cr:YSGG laser (LS). Following surface treatment, the surface roughness and surface topography of the specimens were examined. X-ray diffraction (XRD) was conducted. In addition, the biaxial flexural strengths of specimens were evaluated. The data were analyzed using one-way analysis of variance (ANOVA) and post hoc Tukey tests; the Pearson correlation coefficient was calculated between either volumetric percentage of monoclinic phase or roughness and flexural strength of specimens (α=0.05). Results. The GB group exhibited significantly greater surface roughness compared to the other groups (P

Oxides with different crystal phases can have important effects on the configuration of surface atoms, which can further affect the distribution of hydrogenation sites and acidic sites as well as the competitions of these varied types of catalytic sites. This could be potentially used to tailor the distribution of the products. In this study, zirconium oxides with different crystal phases supported copper catalysts were prepared for the hydrogenation of the biomass-derived furfural, vanillin, etc. The results showed that both calcination temperature and Cu species affected the shift of zirconia from tetragonal phase to the monoclinic phase. Monoclinic zirconia supported copper catalyst can effectively catalyze the hydrogenation of furfural to furfuryl alcohol via hydrogenation route due to its low amount of Bronsted acidic sites, although the surface area and the exposed metallic Cu surface area were much lower than the tetragonal zirconia supported copper catalyst. Zirconia with tetragonal or tetragonal/monoclinic phases supported copper catalysts contain abundant acidic sites and especially the Bronsted acidic sites, which catalyzed mainly the conversion of furfural via the acid-catalyzed routes such as the acetalization, rather than the hydrogenation. The acidic sites over the Cu/ZrO2 catalyst played more predominant roles than the hydrogenation sites in determining the conversion of the organics like furfural and vanillin.

Scandia stabilized zirconia (ScSZ) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC), but high sintering temperature was always required to achieve high density and electrical conductivity. Herein, high-performance ScSZ ceramics were prepared at low temperature by using the cold sintering process (CSP) associated with post-heat-treatment (PHT). Firstly, 8 mol% ScSZ nano powder was synthesized by an ethanol-assisted two step hydrothermal method. Then, ScSZ ceramics were prepared by using CSP and PHT (CSP-PHT). It was found that the relative density of the green body made by CSP at 180 ○C could exceed 70%, which rose to 96.8% after post-heat-treatment at 1200 ○C, higher than that prepared by conventional sintering method at elevated temperature of 1400 ○C with the relative density of 95.4%. Impedance spectra measured at 800 ○C showed the electrical conductivity of ScSZ ceramics prepared by CSP-PHT at 1200 ○C was 0.115 S/cm, prior to that prepared by the CS at 1400 ○C with electrical conductivity of 0.111S/cm. Our results demonstrate that the CSP is a promising method for preparing high performance ScSZ ceramics at reduced temperature.

Sintering is a comprehensive process that involves complex evolution of material microstructures and properties, being recognized as a key factor to improve the machinability of ceramics. The present study aims to address the densification mechanisms of 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) based on the properly designed sintering experiments. The impacts of sintering temperature on the grain growth, phase composition, and mechanical properties were rigorously studied. A particular focus is placed on identifying the correlations between the sintering scheme and the machinability of 3Y-TZP by conducting a series of milling tests. The acquired results indicate that the porous zirconia begins to crystallize at 1100 °C and gradually converts to ceramic characteristics after 1200 °C, resulting in a significant increase of cutting forces and temperatures. Moreover, the zirconia sample sintered at 1200 °C exhibits obvious ductile-brittle removal characteristics and moderate hardness. Thus, a precise control of the machined surface quality can be achieved by cutting within the ductile regime.

In present work, nano-carbon/ceramic composites are fabricated via facile reductive sintering of gel-casted bodies by utilizing different ceramic matrices of alumina and zirconia, respectively. With detailed characterizations of microstructure, bulk density and crystallinity of composites obtained at different sintering temperatures, as well as corresponding residual amount, chemical structure and bonding state of nano-carbon network, the influence of ceramic matrix on semi-conductive properties with respects to electrical conductivity, carrier density and mobility are systemically investigated. It is clarified that ceramic matrix plays an important role in tailoring the state of nano-carbon generated through ceramic particle surface and interface, which determines the resultant semi-conductive properties of composites.

In this paper, the stability of CaO doped partially stabilised zirconia (CaO-PSZ) prepared by electrofusion method was improved from 88.14% to 95% within 1 h using the microwave heating method. The increase of the stability rate was because of the microwave heating method's advantages, including selective heating and fast heating. Analysis techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM), were used to analysis the influences of the holding time (1–4 h) on the CaO doped PSZ samples at a heating temperature of 1100 °C to understand the fundamental mechanism of the optimisation process. The Raman and XRD spectra were fitted by the Gaussian method to further analysis the effect of holding time on the microstructure evolution of the samples. The fitting results indicated that the sample's crystal quality and stability were improved after microwave heating, and the optimised holding time is 2 h.

Nano CeO2–ZrO2 composites with different shapes are synthesized by using hydrothermal and deposition-precipitation methods, and used to obtain Pt/CeO2–ZrO2/RGO catalysts, where reduced graphene oxide(RGO) acts as a carrier. X-ray Diffrattometry (XRD), Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS) detection methods are used to characterize morphology, phase composition, exposed planes and oxygen defects of the catalyst. The obtained CeO2–ZrO2 supports are in the form of nanorods, nanospheres, and nanocubes, which mainly expose (110), (111), and (100) planes, respectively. Electrocatalytic methanol oxidation tests onto the Pt/CeO2–ZrO2/RGO catalysts show that the electrochemically active surface area and the peak current density of nanorods are the largest ones among the three catalysts, reaching 61.4 m2/g and 230 A/g. In addition, the long-term discharge stability and CO poisoning resistance of the nanorod-shaped Pt/CeO2–ZrO2/RGO catalyst are the highest ones among the examined catalysts.

The effect of technological conditions of the process and zirconia (ZrO(2)) nanoparticles on the properties of fine-fibrous filter materials (FMs) obtained by matrix polymer extraction from a microfibrillar composite formed using the material extrusion-based additive manufacturing method from a polypropylene (PP)/copolyamide blend is studied. Different processing schemes were used for obtaining filaments for material extrusion: scheme I—the use of a single-screw extruder at the stage of compounding; scheme II—the use of a single-screw extruder at the stage of compounding and orientational stretching in the course of strand formation; scheme III—the use of a twin-screw extruder at the stage of compounding, scheme IV—the addition of ZrO(2) nanoparticles and use of a twin-screw extruder. It has been shown the possibility of reducing the diameters of the formed in situ PP microfibrils by using the twin-screw extruder, as well as additional orientation drawing. The introduction into the melt of ZrO(2) nanoparticles provides further improvement of the microstructure—the average diameter of the microfibrils is reduced by 1.4 times compared with the initial blend. Developed FMs are characterized by high efficiency of air purification from solid particles with a size of 0.3 μm. At the same time, the use of nanoadditives is the most effective—a two-layer FM with nanoparticles provides cleaning efficiency at the level of four- to six-layer materials without filler.

Colloidal silica is usually used for the chemical mechanical polishing of zirconia ceramic wafer in industry, but the process is often optimized only through experience without a precise understanding of the polishing mechanism. There are still many theoretical and technical issues, especially the material removal mechanism and the effect of polishing on the phase transformation, have not been studied in depth. In this study, the effect of the abrasive concentration, polishing pressure and slurry pH on the material removal rate was analyzed. It is found that the removal rate tends to be stable when the concentration exceeds 30 wt%; the influence of pressure on the polishing rate conforms to the Preston formula. When the pH of the slurry is 6, the removal rate is the highest, but polishing under acidic conditions will leave corrosion pits due to the dissolution of the stabilizer. Through X-ray photoelectron spectroscopy analysis of the residue on the wafer surface, it was found that Si-O-Zr bonds were formed, but it was uncertain whether the residue was zirconium silicate. Through X-ray diffraction analysis, it is found that polishing will not affect the crystal structure of zirconia. The Zr-O-Si bond formed by tribochemical action on the ceramic surface prevents the deep migration of surface hydroxyl groups. At the same time, kinetic factors will cause internal hydroxyl groups to transfer to the surface for recovery oxygen vacancies, thereby stabilizing the tetragonal phase.

PURPOSE This study aimed to compare the microshear bond strength (µSBS) of dual-cure resin cement in CAD-CAM zirconia after different cleaning techniques. MATERIALS AND METHODS Fifty discs of zirconia-based ceramic from Ivoclar Vivadent were embedded in acrylic resin. The discs were divided into five groups according to the cleaning methods used: Group 1: drying with spraying + sandblasting with Al2O3; Group 2: washed with water and dried with spraying + sandblasting with Al2O3; Group 3: washed with distilled water and dried with spraying + sandblasting with Al2O3 + zirconium oxide (Ivoclean); Group 4: washed with distilled water and dried with spraying + sandblasting with Al2O3 + potassium hydroxide (Zirclean); and Group 5: washed with distilled water and dried with spraying + sandblasting with Al2O3 + 1% NaClO. All of the groups were contaminated with artificial saliva for 1 minute and then cleaned. Statistical analyses were performed using ANOVA and Tukey's tests. RESULTS There were statistically significant differences among all groups for µSBS (P < .05). The group treated with zirconium oxide (Group 3) showed the highest µSBS (18.75 ± 0.23 MPa). CONCLUSION When applied to zirconia, the cleaning methods affected the bonding with resin cement differently.

The effects of microwave power and sample quality on microwave drying kinetics and characteristics of zirconia were studied. It is found that by increasing the microwave power and decreasing the sample mass, the surface diffusion coefficient (Deff) appears to an upward tendency. The corresponding value Deff at a sample mass of 10, 20, 30, and 40g are 1.849E-14, 2.443E-14, 3.210E-14, and 3.278E-14 m2/s, respectively. The corresponding value Deff at a microwave power of 300, 400, 500, 600, and 700W are 1.270E-14, 1.784E-14, 2.619E-14, 3.392E-14, and 4.497E-14 m2/s, respectively. Besides, the materials were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR) to evaluate the changes of materials before and after drying. The results show that microwave accelerates the drying of zirconia and increases its dispersibility. The heat conduction direction of microwave drying is the same as that of moisture diffusion, which avoids being affected by heat inertia and heat transfer loss. The drying process is fast and efficient, and the microwave directly penetrates the product, avoiding the disadvantage of slow evaporation caused by the temperature gradient.

Samples of YAG : Се optical ceramics with an activator concentration of 0.5, 1, 5, and 10 at. % were synthesized by a solid-phase method. The synthesis of the samples containing 10 at. % Ce was accompanied by a significant decrease in the weight (to 11.69 wt %) and an anomalous growth of crystallites more than 2 mm in size. The effect of the type of the sintering additive and the activator concentration on the physicochemical properties of the YAG : Ce ceramics was determined. The use of silica as a sintering additive was found to require higher temperatures for the synthesis of the ceramics than the use of zirconia. The activator (cerium) in YAG was observed to behave as a sintering additive, accelerating mass-transfer processes. The luminescence properties of the synthesized samples excited by pulsed and stationary X-ray sources were studied. The relationships between the emissions of Ce3+ and YAl antisite defects, and between the timing performance and the concentration quenching were considered. The ceramic sample with a cerium concentration of 0.5 at. % demonstrated the maximum intensity of the Ce3+ emission band, and the sample containing 10 at. % showed the fastest luminescence response (67 ns).

Introduction: zirconia represents a valuable material that combines both color acceptance and ability to withstand high loads. It had been reported that sintering of zirconia followed by air-borne particle abrasion affect its strength. The effect of air-borne particle abrasion/sintering sequence on shear bond strength of resin cements to zirconia was found non-significant; however the effect of sequence on the flexural strength has not been reported. The Ivoclare Vivadent manufacturer recommendation is to sinter the zirconia before subjecting it to air-borne particle abrasion. Aim of the study: to evaluate the effect of air-borne particle abrasion/sintering sequence on the flexural strength of zirconia. Materials and Method: forty bars of dimensions (26 × 6 × 1.5 millimeter) were fabricated from IPS e-max zircad. The specimens was divided into two equal groups (A and B). Group A (AS) were subjected to air-borne particle abrasion followed by sintering. However specimens of group B (SA) were sintered before air-borne particle abrasion. Specimens of each group were subjected to X-Ray Diffraction to show monoclinic-tetragonal phases percentage. Three-point loading was applied to all specimens to measure the flexural strength using a Universal Testing Machine. Results: At statistically significant level p ≤ 0.05. Group SA has showed significantly higher flexural strength compared to group AS. Air-borne particle abraded surface of group SA showed the highest amount of monoclinic phase crystals after X-Ray Diffraction analysis. Conclusion: Air-borne particle abrasion/sintering sequence affects zirconia’ flexural strength. And air-borne particle abrasion surface treatment induces tetragonal to monoclinic phase transformation in fully sintered zirconia.

The contact between a glass melt and some refractories in glass industry is able to induce a blistering phenomenon, which is detrimental for obtaining high quality glasses. The objective of this study is to define the key parameters of the blistering process and to propose a mechanism for blistering of soda–lime–silica glass melts in contact with fused-cast zirconia-based refractories. The roles of oxygen semipermeability through the zirconia skeleton and of temperature are emphasized.

ZrO2/g-C3N4 semiconductor photocatalytic materials were prepared by ultrasonic method. The effect of zirconia with different crystal structure on visible light photocatalytic activity of ZrO2/g-C3N4 composite was investigated. Loading monoclinic and tetragonal mixed crystals ZrO2 can improve the photocatalytic degradation efficiency of g-C3N4. The optimum composite with 15 wt% ZrO2/g-C3N4 showed the superior photocatalytic activity for degradation of RhB and PNP under visible-light irradiation, which are 2.5 and 2.8 times higher than pure g-C3N4 under same conditions. The main active species affecting photocatalytic degradation are holes (hVB+) and ·O2− by photocatalytic active species capture experiment, ·OH is also partially involved in the photocatalytic degradation. The 15 wt% ZrO2/g-C3N4 has excellent catalytic performance and good stability in photocatalytic repeated experiments, and has a broad application prospect.