Alumina-Reinforced Zirconia Composites

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Bansal, Narottam P.

2003-01-01

Alumina-reinforced zirconia composites, used as electrolyte materials for solid oxide fuel cells, were fabricated by hot pressing 10 mol percent yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina particulates and platelets each containing 0 to 30 mol percent alumina. Major mechanical and physical properties of both particulate and platelet composites including flexure strength, fracture toughness, slow crack growth, elastic modulus, density, Vickers microhardness, thermal conductivity, and microstructures were determined as a function of alumina content either at 25 C or at both 25 and 1000 C. Flexure strength and fracture toughness at 1000 C were maximized with 30 particulate and 30 mol percent platelet composites, respectively, while resistance to slow crack growth at 1000 C in air was greater for 30 mol percent platelet composite than for 30 mol percent particulate composites.

Strength and Fracture Toughness of Solid Oxide Fuel Cell Electrolyte Material Improved

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Choi, Sung R.

2002-01-01

Solid oxide fuel cells (SOFC) are being developed for various applications in the automobile, power-generation, and aeronautics industries. Recently, the NASA Glenn Research Center has been exploring the possibility of using SOFC's for aeropropulsion under its Zero Carbon Dioxide Emission Technology (ZCET) Program. 10-mol% yttriastabilized zirconia (10YSZ) is a very good anionic conductor at high temperatures and is, therefore, used as an oxygen solid electrolyte in SOFC. However, it has a high thermal expansion coefficient, low thermal shock resistance, low fracture toughness, and poor mechanical strength. For aeronautic applications, the thin ceramic electrolyte membrane of the SOFC needs to be strong and tough. Therefore, we have been investigating the possibility of enhancing the strength and fracture toughness of the 10YSZ electrolyte without degrading its electrical conductivity to an appreciable extent. We recently demonstrated that the addition of alumina to zirconia electrolyte increases its strength as well as its fracture toughness. Zirconia-alumina composites containing 0 to 30 mol% of alumina were fabricated by hot pressing. The hot pressing procedure was developed and various hot pressing parameters were optimized, resulting in dense, crackfree panels of composite materials. Cubic zirconia and a-alumina were the only phases detected, indicating that there was no chemical reaction between the constituents during hot pressing at elevated temperatures. Flexure strength sf and fracture toughness K(sub IC) of the various zirconia-alumina composites were measured at room temperature as well as at 1000 C in air. Both properties showed systematic improvement with increased alumina addition at room temperature and at 1000 C. Use of these modified electrolytes with improved strength and fracture toughness should prolong the life and enhance the performance of SOFC in aeronautics and other applications.

Zirconia based dental ceramics: structure, mechanical properties, biocompatibility and applications.

PubMed

Gautam, Chandkiram; Joyner, Jarin; Gautam, Amarendra; Rao, Jitendra; Vajtai, Robert

2016-12-06

Zirconia (ZrO 2 ) based dental ceramics have been considered to be advantageous materials with adequate mechanical properties for the manufacturing of medical devices. Due to its very high compression strength of 2000 MPa, ZrO 2 can resist differing mechanical environments. During the crack propagation on the application of stress on the surface of ZrO 2 , a crystalline modification diminishes the propagation of cracks. In addition, zirconia's biocompatibility has been studied in vivo, leading to the observation of no adverse response upon the insertion of ZrO 2 samples into the bone or muscle. In vitro experimentation has exhibited the absence of mutations and good viability of cells cultured on this material leading to the use of ZrO 2 in the manufacturing of hip head prostheses. The mechanical properties of zirconia fixed partial dentures (FPDs) have proven to be superior to other ceramic/composite restorations and hence leading to their significant applications in implant supported rehabilitations. Recent developments were focused on the synthesis of zirconia based dental materials. More recently, zirconia has been introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures in combination with computer aided design/computer aided manufacturing (CAD/CAM) techniques. This systematic review covers the results of past as well as recent scientific studies on the properties of zirconia based ceramics such as their specific compositions, microstructures, mechanical strength, biocompatibility and other applications in dentistry.

Internal coating of zirconia restoration with silica-based ceramic improves bonding of resin cement to dental zirconia ceramic.

PubMed

Kitayama, Shuzo; Nikaido, Toru; Ikeda, Masaomi; Alireza, Sadr; Miura, Hiroyuki; Tagami, Junji

2010-01-01

Resin bonding to zirconia ceramic cannot be established by standard methods that are utilized for conventional silica-based dental ceramics. This study was aimed to examine the tensile bond strength of resin cement to zirconia ceramic using a new laboratory technique. Sixty-four zirconia ceramic specimens were air-abraded using Al2O3 particles and divided into two groups; the control group with no pretreatment (Control), and the group pretreated using the internal coating technique (INT), in which the surface of the zirconia specimens were thinly coated by fusing silica-based ceramic and air-abraded in the same manner. The specimens in each group were further divided into two subgroups according to the silane coupling agents applied; a mixture of dentin primer/silane coupling agent (Clearfil SE Bond Primer/Porcelain Bond Activator) or a newly developed single-component silane coupling agent (Clearfil Ceramic Primer). After bonding with dual-cured resin cement (Panavia F 2.0), they were stored in water for 24 h and half of them were additionally subjected to thermal cycling. The tensile bond strengths were tested using a universal testing machine. ANOVAs revealed significant influence of ceramic surface pretreatment (p<0.001), silane coupling agent (p<0.001) and thermal cycling (p<0.001); the INT coating technique significantly increased the bond strengths of resin cement to zirconia ceramic, whereas thermal cycling significantly decreased the bond strengths. The use of a single-component silane coupling agent demonstrated significantly higher bond strengths than that of a mixture of dentin primer/silane coupling agent. The internal coating of zirconia dental restorations with silica-based ceramic followed by silanization may be indicated in order to achieve better bonding for the clinical success.

Zirconia in dentistry: part 2. Evidence-based clinical breakthrough.

PubMed

Koutayas, Spiridon Oumvertos; Vagkopoulou, Thaleia; Pelekanos, Stavros; Koidis, Petros; Strub, Jörg Rudolf

2009-01-01

An ideal all-ceramic restoration that conforms well and demonstrates enhanced biocompatibility, strength, fit, and esthetics has always been desirable in clinical dentistry. However, the inherent brittleness, low flexural strength, and fracture toughness of conventional glass and alumina ceramics have been the main obstacles for extensive use. The recent introduction of zirconia-based ceramics as a restorative dental material has generated considerable interest in the dental community, which has been expressed with extensive industrial, clinical, and research activity. Contemporary zirconia powder technology contributes to the fabrication of new biocompatible all-ceramic restorations with improved physical properties for a wide range of promising clinical applications. Especially with the development of computer-aided design (CAD)/computer-aided manufacturing (CAM) systems, high-strength zirconia frameworks can be viable for the fabrication of full and partial coverage crowns, fixed partial dentures, veneers, posts and/or cores, primary double crowns, implant abutments, and implants. Data from laboratory and clinical studies are promising regarding their performance and survival. However, clinical data are considered insufficient and the identified premature complications should guide future research. In addition, different zirconia-based dental auxiliary components (i.e., cutting burs and surgical drills, extra-coronal attachments and orthodontic brackets) can also be technologically feasible. This review aims to present and discuss zirconia manufacturing methods and their potential for successful clinical application in dentistry.

Alumina additions may improve the damage tolerance of soft machined zirconia-based ceramics.

PubMed

Oilo, Marit; Tvinnereim, Helene M; Gjerdet, Nils Roar

2011-01-01

The aim of this study was to evaluate the damage tolerance of different zirconia-based materials. Bars of one hard machined and one soft machined dental zirconia and an experimental 95% zirconia 5% alumina ceramic were subjected to 100,000 stress cycles (n = 10), indented to provoke cracks on the tensile stress side (n = 10), and left untreated as controls (n = 10). The experimental material demonstrated a higher relative damage tolerance, with a 40% reduction compared to 68% for the hard machined zirconia and 84% for the soft machined zirconia.

Electrolytes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Fergus, Jeffrey W.

The high operating temperature of solid oxide fuel cells (SOFCs), as compared to polymer electrolyte membrane fuel cells (PEMFCs), improves tolerance to impurities in the fuel, but also creates challenges in the development of suitable materials for the various fuel cell components. In response to these challenges, intermediate temperature solid oxide fuel cells (IT-SOFCs) are being developed to reduce high-temperature material requirements, which will extend useful lifetime, improve durability and reduce cost, while maintaining good fuel flexibility. A major challenge in reducing the operating temperature of SOFCs is the development of solid electrolyte materials with sufficient conductivity to maintain acceptably low ohmic losses during operation. In this paper, solid electrolytes being developed for solid oxide fuel cells, including zirconia-, ceria- and lanthanum gallate-based materials, are reviewed and compared. The focus is on the conductivity, but other issues, such as compatibility with electrode materials, are also discussed.

High strength porous support tubes for high temperature solid electrolyte electrochemical cells

DOEpatents

Rossing, Barry R.; Zymboly, Gregory E.

1986-01-01

A high temperature, solid electrolyte electrochemical cell is made, having an electrode and a solid electrolyte disposed on a porous, sintered support material containing thermally stabilized zirconia powder particles and from about 3 wt. % to about 45 wt. % of thermally stable oxide fibers.

Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

NASA Astrophysics Data System (ADS)

Panthi, Dhruba; Tsutsumi, Atsushi

2014-08-01

Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)-YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm-2 at 850, 800, and 750°C, respectively.

Zirconia in fixed prosthesis. A literature review

PubMed Central

Román-Rodríguez, Juan L.; Ferreiroa, Alberto; Solá-Ruíz, María F.; Fons-Font, Antonio

2014-01-01

Statement of problem: Evidence is limited on the efficacy of zirconia-based fixed dental prostheses. Objective: To carry out a literature review of the behavior of zirconium oxide dental restorations. Material and Methods: This literature review searched the Pubmed, Scopus, Medline and Cochrane Library databases using key search words “zirconium oxide,” “zirconia,” “non-metal restorations,” “ceramic oxides,” “veneering ceramic,” “zirconia-based fixed dental prostheses”. Both in vivo and in vitro studies into zirconia-based prosthodontic restoration behavior were included. Results: Clinical studies have revealed a high rate of fracture for porcelain-veneered zirconia-based restorations that varies between 6% and 15% over a 3- to 5-year period, while for ceramo-metallic restorations the fracture rate ranges between 4 and 10% over ten years. These results provoke uncertainty as to the long-term prognosis for this material in the oral medium. The cause of veneering porcelain fractures is unknown but hypothetically they could be associated with bond failure between the veneer material and the zirconia sub-structure. Key words:Veneering ceramic, zirconia-based ceramic restoration, crown, zirconia, tooth-supported fixed prosthesis. PMID:24596638

Fuel electrode containing pre-sintered nickel/zirconia for a solid oxide fuel cell

DOEpatents

Ruka, Roswell J.; Vora, Shailesh D.

2001-01-01

A fuel cell structure (2) is provided, having a pre-sintered nickel-zirconia fuel electrode (6) and an air electrode (4), with a ceramic electrolyte (5) disposed between the electrodes, where the pre-sintered fuel electrode (6) contains particles selected from the group consisting of nickel oxide, cobalt and cerium dioxide particles and mixtures thereof, and titanium dioxide particles, within a matrix of yttria-stabilized zirconia and spaced-apart filamentary nickel strings having a chain structure, and where the fuel electrode can be sintered to provide an active solid oxide fuel cell.

Fracture resistance of zirconia-based implant abutments after artificial long-term aging.

PubMed

Alsahhaf, Abdulaziz; Spies, Benedikt Christopher; Vach, Kirstin; Kohal, Ralf-Joachim

2017-02-01

To investigate the survival rate, fracture strength, bending moments, loading to fracture and fracture modes of different designs of zirconia abutments after dynamic loading with thermocycling, and compare these values to titanium abutments. A total of 80 abutment samples were divided into 5 test groups of 16 samples in each group. The study included the following groups, "Group 1" CAD/CAM produced all-zirconia abutments, "Group 2" titanium abutments, "Group 3" zirconia-abutments adhesively luted to a titanium base, "Group 4" prefabricated all-zirconia abutments and "Group 5" zirconia-abutments glass soldered to a titanium base. Half the number of samples in each group was exposed to 1.2 million loading cycles (5-years simulation) in the chewing simulator. The samples that survived the artificial aging were later tested for fracture strength in a universal testing machine. The remaining 8 samples of the group were directly tested for fracture strength. All samples exposed to the 5-years artificial aging survived except of six samples in one group (Group 1). The surviving samples were later fracture tested in the universal testing machine. The bending moments (Ncm) values were as follow: Exposed groups: "Group 1" 94.5Ncm; "Group 2" 599.2Ncm; "Group 3" 477.5Ncm; "Group 4" 314.4Ncm; "Group 5" 509.4Ncm. Non-exposed groups: "Group 1" 269.3Ncm; "Group 2" 474.2Ncm; "Group 3" 377.6Ncm; "Group 4" 265.4Ncm; "Group 5" 372.4Ncm. Except in Group 1, the values were higher in the exposed groups, although, statistically there was no difference (p>0.05). The one-piece ZrO2-abutment group (Group 1 and Group 4) exhibited lower values, while the two-piece ZrO2-abutment groups (Group 3 and Group 5) showed similar values and fracture modes like the titanium abutment group. The titanium abutment group showed the highest values of bending moments among all groups. The implant-abutment connection area appeared to influence the bending moment value and the fracture mode of the tested

In vitro comparison of fracture load of implant-supported, zirconia-based, porcelain- and composite-layered restorations after artificial aging.

PubMed

Komine, Futoshi; Taguchi, Kohei; Fushiki, Ryosuke; Kamio, Shingo; Iwasaki, Taro; Matsumura, Hideo

2014-01-01

This study evaluated fracture load of single-tooth, implant-supported, zirconia-based, porcelain- and indirect composite-layered restorations after artificial aging. Forty-four zirconia-based molar restorations were fabricated on implant abutments and divided into four groups, namely, zirconia-based all-ceramic restorations (ZAC group) and three types of zirconia-based composite-layered restorations (ZIC-P, ZIC-E, and ZIC groups). Before layering an indirect composite material, the zirconia copings in the ZIC-P and ZIC-E groups were primed with Clearfil Photo Bond and Estenia Opaque Primer, respectively. All restorations were cemented on the abutments with glass-ionomer cement and then subjected to thermal cycling and cyclic loading. All specimens survived thermal cycling and cyclic loading. The fracture load of the ZIC-P group (2.72 kN) was not significantly different from that of the ZAC group (3.05 kN). The fracture load of the zirconia-based composite-layered restoration primed with Clearfil Photo Bond (ZIC-P) was comparable to that of the zirconia-based all-ceramic restoration (ZAC) after artificial aging.

Zirconia in biomedical applications.

PubMed

Chen, Yen-Wei; Moussi, Joelle; Drury, Jeanie L; Wataha, John C

2016-10-01

The use of zirconia in medicine and dentistry has rapidly expanded over the past decade, driven by its advantageous physical, biological, esthetic, and corrosion properties. Zirconia orthopedic hip replacements have shown superior wear-resistance over other systems; however, risk of catastrophic fracture remains a concern. In dentistry, zirconia has been widely adopted for endosseous implants, implant abutments, and all-ceramic crowns. Because of an increasing demand for esthetically pleasing dental restorations, zirconia-based ceramic restorations have become one of the dominant restorative choices. Areas covered: This review provides an updated overview of the applications of zirconia in medicine and dentistry with a focus on dental applications. The MEDLINE electronic database (via PubMed) was searched, and relevant original and review articles from 2010 to 2016 were included. Expert commentary: Recent data suggest that zirconia performs favorably in both orthopedic and dental applications, but quality long-term clinical data remain scarce. Concerns about the effects of wear, crystalline degradation, crack propagation, and catastrophic fracture are still debated. The future of zirconia in biomedical applications will depend on the generation of these data to resolve concerns.

Fabrication and Characterization of Dense Zirconia and Zirconia-Silica Ceramic Nanofibers

PubMed Central

Guo, Guangqing; Fan, Yuwei

2011-01-01

The objective of this study was to prepare dense zirconia-yttria (ZY), zirconia-silica (ZS) and zirconia-yttria-silica (ZYS) nanofibers as reinforcing elements for dental composites. Zirconium (IV) propoxide, yttrium nitrate hexahydrate, and tetraethyl orthosilicate (TEOS) were used as precursors for the preparation of zirconia, yttria, and silica sols. A small amount (1–1.5 wt%) of polyethylene oxide (PEO) was used as a carry polymer. The sols were preheated at 70 °C before electrospinning and their viscosity was measured with a viscometer at different heating time. The gel point was determined by viscosity–time (η–t) curve. The ZY, ZS and ZYS gel nanofibers were prepared using a special reactive electrospinning device under the conditions near the gel point. The as-prepared gel nanofibers had diameters between 200 and 400 nm. Dense (nonporous) ceramic nanofibers of zirconia-yttria (96/4), zirconia-silica (80/20) and zirconia-yttria-silica (76.8/3.2/20) with diameter of 100–300 nm were obtained by subsequent calcinations at different temperatures. The gel and ceramic nanofibers obtained were characterized by scanning electron microscope (SEM), high-resolution field-emission scanning electron microscope (FE-SEM), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectrometer (FT-IR), and X-ray diffraction (XRD). SEM micrograph revealed that ceramic ZY nanofibers had grained structure, while ceramic ZS and ZYS nanofibers had smooth surfaces, both showing no visible porosity under FE-SEM. Complete removal of the polymer PEO was confirmed by TGA/DSC and FT-IR. The formation of tetragonal phase of zirconia and amorphous silica was proved by XRD. In conclusion, dense zirconia-based ceramic nanofibers can be fabricated using the new reactive sol–gel electrospinning technology with minimum organic polymer additives. PMID:21133090

Method for producing electricity from a fuel cell having solid-oxide ionic electrolyte

DOEpatents

Mason, David M.

1984-01-01

Stabilized quadrivalent cation oxide electrolytes are employed in fuel cells at elevated temperatures with a carbon and/or hydrogen containing fuel anode and an oxygen cathode. The fuel cell is operated at elevated temperatures with conductive metallic coatings as electrodes and desirably having the electrolyte surface blackened. Of particular interest as the quadrivalent oxide is zirconia.

On the interfacial fracture resistance of resin-bonded zirconia and glass-infiltrated graded zirconia

PubMed Central

Chai, Herzl; Kaizer, Marina; Chughtai, Asima; Tong, Hui; Tanaka, Carina; Zhang, Yu

2015-01-01

Objective A major limiting factor for the widespread use of zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded zirconia-based restorative materials. Methods The interfacial fracture energy GC was determined for adhesively bonded zirconia, graded zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline GC was measured for bonded specimens subjected to 7 days hydration at 37 °C. Long-term GC was determined for specimens exposed to 20,000 thermal cycles between 5 and 55 °C followed by 2-month aging at 37 °C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis. Results The baseline and long-term GC for graded zirconia was 2–3 and 8 times that for zirconia, respectively. More significantly, both the baseline and long-term GC of graded zirconia were similar to those for feldspathic ceramic. Significance The interfacial fracture energy of feldspathic ceramic and graded zirconia was controlled by the fracture energy of the resin cement while that of zirconia by the interface. GC for the graded zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry. PMID:26365987

Fabrication of Thin Electrolytes for Second-Generation Solid Oxide Fuel Cells

DTIC Science & Technology

1999-05-05

stabilized zirconia but are equally applicable to components, have been developed. Halogen com- other oxide electrolytes. pounds such as ZrCl4 and YC13...substrates. They used ZrCl4 and an oxygen source reactant. EVD is a two-step YC13 vapor mixtures as the metal compound sources process. The first step...thin zirconia layers on ited film. In this step oxygen ions formed on the porous alumina substrates. ZrCl4 and YC13 vapor water vapor side of the

Yttria-stabilized zirconia solid oxide electrolyte fuel cells: Monolithic solid oxide fuel cells

NASA Astrophysics Data System (ADS)

1990-10-01

The monolithic solid oxide fuel cell (MSOFC) is currently under development for a variety of applications including coal-based power generation. The MSOFC is a design concept that places the thin components of a solid oxide fuel cell in lightweight, compact, corrugated structure, and so achieves high efficiency and excellent performance simultaneously with high power density. The MSOFC can be integrated with coal gasification plants and is expected to have high overall efficiency in the conversion of the chemical energy of coal to electrical energy. This report describes work aimed at: (1) assessing manufacturing costs for the MSOFC and system costs for a coal-based plant; (2) modifying electrodes and electrode/electrolyte interfaces to improve the electrochemical performance of the MSOFC; and (3) testing the performance of the MSOFC on hydrogen and simulated coal gas. Manufacturing costs for both the coflow and crossflow MSOFC's were assessed based on the fabrication flow charts developed by direct scaleup of tape calendering and other laboratory processes. Integrated coal-based MSOFC systems were investigated to determine capital costs and costs of electricity. Design criteria were established for a coal-fueled 200-Mw power plant. Four plant arrangements were evaluated, and plant performance was analyzed. Interfacial modification involved modification of electrodes and electrode/electrolyte interfaces to improve the MSOFC electrochemical performance. Work in the cathode and cathode/electrolyte interface was concentrated on modification of electrode porosity, electrode morphology, electrode material, and interfacial bonding. Modifications of the anode and anode/electrolyte interface included the use of additives and improvement of nickel distribution. Single cells have been tested for their electrochemical performance. Performance data were typically obtained with humidified H2 or simulated coal gas and air or oxygen.

Evaluation of translucency of monolithic zirconia and framework zirconia materials

PubMed Central

Tuncel, İlkin; Üşümez, Aslıhan

2016-01-01

PURPOSE The opacity of zirconia is an esthetic disadvantage that hinders achieving natural and shade-matched restorations. The aim of this study was to evaluate the translucency of non-colored and colored framework zirconia and monolithic zirconia. MATERIALS AND METHODS The three groups tested were: non-colored framework zirconia, colored framework zirconia with the A3 shade according to Vita Classic Scale, and monolithic zirconia (n=5). The specimens were fabricated in the dimensions of 15×12×0.5 mm. A spectrophotometer was used to measure the contrast ratio, which is indicative of translucency. Three measurements were made to obtain the contrast ratios of the materials over a white background (L*w) and a black background (L*b). The data were analyzed using the one-way analysis of variance and Tukey HSD tests. One specimen from each group was chosen for scanning electron microscope analysis. The determined areas of the SEM images were divided by the number of grains in order to calculate the mean grain size. RESULTS Statistically significant differences were observed among all groups (P<.05). Non-colored zirconia had the highest translucency with a contrast ratio of 0.75, while monolithic zirconia had the lowest translucency with a contrast ratio of 0.8. The mean grain sizes of the non-colored, colored, and monolithic zirconia were 233, 256, and 361 nm, respectively. CONCLUSION The translucency of the zirconia was affected by the coloring procedure and the grain size. Although monolithic zirconia may not be the best esthetic material for the anterior region, it may serve as an alternative in the posterior region for the bilayered zirconia restorations. PMID:27350851

Synthesis of zirconia monoliths for chromatographic separations.

PubMed

Randon, Jérôme; Huguet, Samuel; Piram, Anne; Puy, Guillaume; Demesmay, Claire; Rocca, Jean-Louis

2006-03-17

The aim of this work is to join the advantages of two different kinds of stationary phases: monolithic columns and zirconia-based supports. On the one hand, silica monolithic columns allow a higher efficiency with a lower back-pressure than traditional packed columns. On the other hand, chromatographic stationary phases based on zirconia have a higher thermal and chemical stability and specific surface properties. Combining these advantages, a zirconia monolith with a macroporous framework could be a real improvement in separation sciences. Two main strategies can be used in order to obtain a zirconia surface on a monolithic skeleton: coating or direct synthesis. The coverage by a zirconia layer of the surface of a silica-based monolith can be performed using the chemical properties of the silanol surface groups. We realized this coverage using zirconium alkoxide and we further grafted n-dodecyl groups using phosphate derivatives. Any loss of efficiency was observed and fast separations have been achieved. The main advance reported in this paper is related to the preparation of zirconia monoliths by a sol-gel process starting from zirconium alkoxide. The synthesis parameters (hydrolysis ratio, porogen type, precursor concentration, drying step, etc.) were defined in order to produce a macroporous zirconia monoliths usable in separation techniques. We produced various homogeneous structures: zirconia rod 2 cm long with a diameter of 2.3 mm, and zirconia monolith inside fused silica capillaries with a 75 microm I.D. These monoliths have a skeleton size of 2 microm and have an average through pore size of 6 microm. Several separations have been reported.

Influence of different resin cements and surface treatments on microshear bond strength of zirconia-based ceramics

PubMed Central

Petrauskas, Anderson; Novaes Olivieri, Karina Andrea; Pupo, Yasmine Mendes; Berger, Guilherme; Gonçalves Betiol, Ederson Áureo

2018-01-01

Aim: This study aims to evaluate the microshear bond strength of zirconia-based ceramics with different resin cement systems and surface treatments. Materials and Methods: Forty blocks of zirconia-based ceramic were prepared and embedded in polyvinyl chloride (PVC) tubes with acrylic resin. After polishing, the samples were washed in an ultrasonic bath and dried in an oven for 10 min. Half of the samples were subjected to sandblasting with aluminum oxide. Blocks were divided into four groups (n = 10) in which two resin cements were used as follows: (1) RelyX™ U100 with surface-polished zirconia; (2) RelyX™ U100 with surface-blasted zirconia; (3) Multilink with surface-polished zirconia; and 4) Multilink with surface-blasted zirconia. After performing these surface treatments, translucent tubes (n = 30 per group) were placed on the zirconia specimens, and resin cement was injected into them and light cured. The PVC tubes were adapted in a universal testing machine; a stiletto blade, which was bolted to the machine, was positioned on the cementation interface. The microshear test was performed at a speed of 0.5 mm/min. Failure mode was analyzed in an optical microscope and classified as adhesive, cohesive, or mixed. Results: The null hypothesis of this study was rejected because there was a difference found between the resin cement and the surface treatment. There was a statistical difference (P < 0.005) in RelyX™ U100 with surface-blasted zirconia, in relation to the other three groups. For Multilink groups, there was no statistical difference between them. Conclusion: Self-adhesive resin cement showed a more significant tendency toward bond strength in the ceramic-based zirconium oxide grit-blasted surfaces. PMID:29674825

Effects of framework design and layering material on fracture strength of implant-supported zirconia-based molar crowns.

PubMed

Kamio, Shingo; Komine, Futoshi; Taguchi, Kohei; Iwasaki, Taro; Blatz, Markus B; Matsumura, Hideo

2015-12-01

To evaluate the effects of framework design and layering material on the fracture strength of implant-supported zirconia-based molar crowns. Sixty-six titanium abutments (GingiHue Post) were tightened onto dental implants (Implant Lab Analog). These abutment-implant complexes were randomly divided into three groups (n = 22) according to the design of the zirconia framework (Katana), namely, uniform-thickness (UNI), anatomic (ANA), and supported anatomic (SUP) designs. The specimens in each design group were further divided into two subgroups (n = 11): zirconia-based all-ceramic restorations (ZAC group) and zirconia-based restorations with an indirect composite material (Estenia C&B) layered onto the zirconia framework (ZIC group). All crowns were cemented on implant abutments, after which the specimens were tested for fracture resistance. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test with the Bonferroni correction (α = 0.05). The following mean fracture strength values (kN) were obtained in UNI design, ANA design, and SUP design, respectively: Group ZAC, 3.78, 6.01, 6.50 and Group ZIC, 3.15, 5.65, 5.83. In both the ZAC and ZIC groups, fracture strength was significantly lower for the UNI design than the other two framework designs (P = 0.001). Fracture strength did not significantly differ (P > 0.420) between identical framework designs in the ZAC and ZIC groups. A framework design with standardized layer thickness and adequate support of veneer by zirconia frameworks, as in the ANA and SUP designs, increases fracture resistance in implant-supported zirconia-based restorations under conditions of chewing attrition. Indirect composite material and porcelain perform similarly as layering materials on zirconia frameworks. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Zirconia coated carbonyl iron particle-based magnetorheological fluid for polishing

NASA Astrophysics Data System (ADS)

Shafrir, Shai N.; Romanofsky, Henry J.; Skarlinski, Michael; Wang, Mimi; Miao, Chunlin; Salzman, Sivan; Chartier, Taylor; Mici, Joni; Lambropoulos, John C.; Shen, Rui; Yang, Hong; Jacobs, Stephen D.

2009-08-01

Aqueous magnetorheological (MR) polishing fluids used in magnetorheological finishing (MRF) have a high solids concentration consisting of magnetic carbonyl iron particles and nonmagnetic polishing abrasives. The properties of MR polishing fluids are affected over time by corrosion of CI particles. Here we report on MRF spotting experiments performed on optical glasses using a zirconia coated carbonyl iron (CI) particle-based MR fluid. The zirconia coated magnetic CI particles were prepared via sol-gel synthesis in kg quantities. The coating layer was ~50-100 nm thick, faceted in surface structure, and well adhered. Coated particles showed long term stability against aqueous corrosion. "Free" nano-crystalline zirconia polishing abrasives were co-generated in the coating process, resulting in an abrasivecharged powder for MRF. A viable MR fluid was prepared simply by adding water. Spot polishing tests were performed on a variety of optical glasses over a period of 3 weeks with no signs of MR fluid degradation or corrosion. Stable material removal rates and smooth surfaces inside spots were obtained.

Using glass-graded zirconia to increase delamination growth resistance in porcelain/zirconia dental structures.

PubMed

Chai, Herzl; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

2018-01-01

Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy G C was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good esthetic quality, graded zirconia emerges as a viable material concept for dental restorations. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Fracture resistance of implant- supported monolithic crowns cemented to zirconia hybrid-abutments: zirconia-based crowns vs. lithium disilicate crowns

PubMed Central

Nawafleh, Noor; Öchsner, Andreas; George, Roy

2018-01-01

PURPOSE The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments. PMID:29503716

Phase Stabilization of Zirconia.

DTIC Science & Technology

1997-01-30

preparing stabilized zirconia pursuant to this disclosure, an insoluble alumina powder is mixed with zirconia powder using a liquid dispersant, such...in a drying oven or a furnace. When mixing the alumina and zirconia powders , it is not necessary to have zirconia in any particular phase to achieve...phase stabilization, as disclosed herein. When mixed with alumina powder, zirconia powder can be in cubic, tetragonal or 20 monoclinic phases

Five-year prospective clinical study of posterior three-unit zirconia-based fixed dental prostheses.

PubMed

Sorrentino, Roberto; De Simone, Giorgio; Tetè, Stefano; Russo, Simona; Zarone, Fernando

2012-06-01

This prospective clinical trial aimed at evaluating the clinical performance of three-unit posterior zirconia fixed dental prostheses (FDPs) after 5 years of clinical function. Thirty-seven patients received 48 three-unit zirconia-based FDPs. The restorations replaced either a premolar or a molar. Specific inclusion criteria were needed. Tooth preparation was standardized. Computer-aided design/computer-assisted manufacturing frameworks with a 9-mm(2) cross section of the connector and a 0.6-mm minimum thickness of the retainer were made. The restorations were luted with resin cement. The patients were recalled after 1, 6, 12, 24, 36, 48, and 60 months. The survival and success of the ceramics and zirconia were evaluated. The technical and aesthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutment and contralateral teeth. Descriptive statistics were performed. All FDPs completed the study, resulting in 100% cumulative survival rate and 91.9% and 95.4% cumulative success rates for patients wearing one and two FDPs, respectively. No losses of retention were recorded. Forty-two restorations were rated alpha in all measured parameters. A minor chipping of the ceramics was detected in three restorations. No significant differences between the periodontal parameters of the test and control teeth were observed. Five-year clinical results proved that three-unit posterior zirconia-based FDPs were successful in the medium term for both function and aesthetic. Zirconia can be considered a promising substitute of metal frameworks for the fabrication of short-span posterior prostheses.

Optical and structural properties of colloidal zirconia nanoparticles prepared by arc discharge in liquid

NASA Astrophysics Data System (ADS)

Peymani forooshani, Reza; Poursalehi, Reza; Yourdkhani, Amin

2018-01-01

Zirconia is one of the important ceramic materials with unique properties such as high melting point, high ionic conductivity, high mechanical properties and low thermal conductivity. Therefore, zirconia is one of the useful materials in refractories, thermal barriers, cutting tools, oxygen sensors electrolytes, catalysis, catalyst supports and solid oxide fuel cells. Recently, direct current (DC) arc discharge is extensively employed to synthesis of metal oxide nanostructures in liquid environments. The aim of this work is the synthesis of colloidal zirconia nanoparticles by DC arc discharge method in water as a medium. Arc discharge was ignited between two pure zirconium electrodes in water. Optical and structural properties of prepared colloidal nanoparticles were investigated. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and UV-visible spectroscopy, were employed for characterization of particle size, morphology, crystal structure and optical properties, respectively. SEM images demonstrate that the nanoparticles are spherical in shape with an average size lower than 38 nm. The XRD patterns of the nanoparticles were consistent with tetragonal and monoclinic zirconia crystal structures. The optical transmission spectra of the colloidal solution show optical characteristic of zirconia nanoparticles as a wide band gap semiconductor with no absorption peak in visible wavelength with the considerable amount of oxygen deficiency. Oxidation of colloidal nanoparticles in water could be explained via reaction with either dissociated oxygen from water in hot plasma region or with dissolved oxygen in water. The results provide a simple and flexible method for preparation of zirconia nanoparticles with a capability of mass production without environmental footprints.

Effects of silane- and MDP-based primers application orders on zirconia-resin adhesion-A ToF-SIMS study.

PubMed

Chuang, Shu-Fen; Kang, Li-Li; Liu, Yi-Chuan; Lin, Jui-Che; Wang, Ching-Cheng; Chen, Hui-Min; Tai, Cheng-Kun

2017-08-01

To evaluate the 3-methacryloyloxypropyltrimethoxysilane (MPS)- and 10-methacryloyloxydecyl-dihydrogen-phosphate (MDP)-base primers, in their single or sequential applications, with regard to modifying zirconia surfaces and improving resin-zirconia adhesion. Zirconia disks received different treatments: without primer (Zr), MPS-base primer (S), MDP-base primer (M), MPS/MDP mixture (SMmix), MPS followed by MDP (SM), and MDP followed by MPS (MS). The compositions and chemical interactions of the coatings to zirconia were analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and reconstructed 3D ion images. Surface wettability of these coatings to water and resin adhesive was assessed. The shear bond strength (SBS) between resin and the treated zirconia was also examined before and after thermocycling. Groups S and MS presented substantial OH - ions in the coatings and zirconia substrate. PO 2 - and PO 3 - fragments existed in all MDP-treatment groups with various proportions and distributions, while groups M and SM showed higher proportions of PO 3 - and the zirconium phosphate related ions. In 3D ion images, PO 3 - in groups M and SM was denser and segregated to the interface, but was dispersed or overlaid above PO 2 - in SMmix and MS. All the primers increased the surface wettability to water and resin, with M and SM presenting superhydrophilic surfaces. All MDP-treatment groups showed improved SBS before thermocycling, while M and SM retained higher SBS after this. The MDP-base primer shows a relevant function in facilitating POZr bonding and enhancing resin-zirconia bonding. The co-treated MPS impairs the chemical activity of MDP, especially if it is the final coat. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Innovations in bonding to zirconia-based materials. Part II: Focusing on chemical interactions.

PubMed

Aboushelib, Moustafa N; Mirmohamadi, Hesam; Matinlinna, Jukka P; Kukk, Edwin; Ounsi, Hani F; Salameh, Ziad

2009-08-01

The zirconia-resin bond strength was enhanced using novel engineered zirconia primers in combination with selective infiltration etching as a surface pre-treatment. The aim of this study was to evaluate the effect of artificial aging on the chemical stability of the established bond and to understand the activation mechanism of the used primers. Selective infiltration etched zirconia discs (Procera; NobelBiocare) were coated with one of four novel engineered zirconia primers containing reactive monomers and were bonded to resin-composite discs (Panavia F2.0). Fourier transform infrared spectroscopy (FT-IR) was carried out to examine the chemical activation of zirconia primers from mixing time and up to 60min. The bilayered specimens were cut into microbars (1mm(2) in cross-section area) and zirconia-resin microtensile bond strength (MTBS) was evaluated immediately and after 90 days of water storage at 37 degrees C. Scanning electron microscopy (SEM) was used to analyze the fracture surface. There was a significant drop in MTBS values after 90 days of water storage for all tested zirconia primers from ca. 28-41MPa to ca. 15-18MPa after completion of artificial aging. SEM revealed increase in percentage of interfacial failure after water storage. FTIR spectra suggested adequate activation of the experimental zirconia primers within 1h of mixing time. The novel engineered zirconia primers produced initially high bond strength values which were significantly reduced after water storage. Long-term bond stability requires developing more stable primers.

Two-body wear comparison of zirconia crown, gold crown, and enamel against zirconia.

PubMed

Kwon, Min-Seok; Oh, Sang-Yeob; Cho, Sung-Am

2015-07-01

Full zirconia crowns have recently been used for dental restorations because of their mechanical properties. However, there is little information about their wear characteristics against enamel, gold, and full zirconia crowns. The purpose of this study was to compare the wear rate of enamel, gold crowns, and zirconia crowns against zirconia blocks using an in vitro wear test. Upper specimens were divided into three groups: 10 enamels (group 1), 10 gold crowns (group 2, Type III gold), and 10 zirconia crowns (group 3, Prettau(®)Zirkon 9H, Zirkonzahn, Italy). Each of these specimens was wear tested against a zirconia block (40×30×3mm(3)) as a lower specimen (30 total zirconia blocks). Each specimen of the groups was abraded against the zirconia block for 600 cycles at 1Hz with 15mm front-to-back movement on an abrading machine. Moreover, the load applied during the abrading test was 50N, and the test was performed in a normal saline emulsion for 10min. Three-dimensional images were taken before and after the test, and the statistical analysis was performed using the Krushal-Wallis test and Mann-Whitney test (p=0.05). The mean volume loss of group 1 was 0.47mm(3), while that of group 2 and group 3 was 0.01mm(3). The wear volume loss of enamels against zirconia was higher than that of gold and zirconia crowns. Moreover, according to this result, zirconia crowns are not recommended for heavy bruxers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Zirconia-coated carbonyl-iron-particle-based magnetorheological fluid for polishing optical glasses and ceramics.

PubMed

Shafrir, Shai N; Romanofsky, Henry J; Skarlinski, Michael; Wang, Mimi; Miao, Chunlin; Salzman, Sivan; Chartier, Taylor; Mici, Joni; Lambropoulos, John C; Shen, Rui; Yang, Hong; Jacobs, Stephen D

2009-12-10

We report on magnetorheological finishing (MRF) spotting experiments performed on glasses and ceramics using a zirconia-coated carbonyl-iron (CI)-particle-based magnetorheological (MR) fluid. The zirconia-coated magnetic CI particles were prepared via sol-gel synthesis in kilogram quantities. The coating layer was approximately 50-100 nm thick, faceted in surface structure, and well adhered. Coated particles showed long-term stability against aqueous corrosion. "Free" nanocrystalline zirconia polishing abrasives were cogenerated in the coating process, resulting in an abrasive-charged powder for MRF. A viable MR fluid was prepared simply by adding water. Spot polishing tests were performed on a variety of optical glasses and ceramics over a period of nearly three weeks with no signs of MR fluid degradation or corrosion. Stable material removal rates and smooth surfaces inside spots were obtained.

Polymeric electrolytes based on hydrosilyation reactions

DOEpatents

Kerr, John Borland [Oakland, CA; Wang, Shanger [Fairfield, CA; Hou, Jun [Painted Post, NY; Sloop, Steven Edward [Berkeley, CA; Han, Yong Bong [Berkeley, CA; Liu, Gao [Oakland, CA

2006-09-05

New polymer electrolytes were prepared by in situ cross-linking of allyl functional polymers based on hydrosilation reaction using a multifunctional silane cross-linker and an organoplatinum catalyst. The new cross-linked electrolytes are insoluble in organic solvent and show much better mechanical strength. In addition, the processability of the polymer electrolyte is maintained since the casting is finished well before the gel formation.

Nanosilica coating for bonding improvements to zirconia.

PubMed

Chen, Chen; Chen, Gang; Xie, Haifeng; Dai, Wenyong; Zhang, Feimin

2013-01-01

Resin bonding to zirconia cannot be established from standard methods that are currently utilized in conventional silica-based dental ceramics. The solution-gelatin (sol-gel) process is a well developed silica-coating technique used to modify the surface of nonsilica-based ceramics. Here, we use this technique to improve resin bonding to zirconia, which we compared to zirconia surfaces treated with alumina sandblasting and tribochemical silica coating. We used the shear bond strength test to examine the effect of the various coatings on the short-term resin bonding of zirconia. Furthermore, we employed field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and Fourier transform infrared spectroscopy to characterize the zirconia surfaces. Water-mist spraying was used to evaluate the durability of the coatings. To evaluate the biological safety of the experimental sol-gel silica coating, we conducted an in vitro Salmonella typhimurium reverse mutation assay (Ames mutagenicity test), cytotoxicity tests, and in vivo oral mucous membrane irritation tests. When compared to the conventional tribochemical silica coating, the experimental sol-gel silica coating provided the same shear bond strength, higher silicon contents, and better durability. Moreover, we observed no apparent mutagenicity, cytotoxicity, or irritation in this study. Therefore, the sol-gel technique represents a promising method for producing silica coatings on zirconia.

Nanosilica coating for bonding improvements to zirconia

PubMed Central

Chen, Chen; Chen, Gang; Xie, Haifeng; Dai, Wenyong; Zhang, Feimin

2013-01-01

Resin bonding to zirconia cannot be established from standard methods that are currently utilized in conventional silica-based dental ceramics. The solution–gelatin (sol–gel) process is a well developed silica-coating technique used to modify the surface of nonsilica-based ceramics. Here, we use this technique to improve resin bonding to zirconia, which we compared to zirconia surfaces treated with alumina sandblasting and tribochemical silica coating. We used the shear bond strength test to examine the effect of the various coatings on the short-term resin bonding of zirconia. Furthermore, we employed field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, and Fourier transform infrared spectroscopy to characterize the zirconia surfaces. Water–mist spraying was used to evaluate the durability of the coatings. To evaluate the biological safety of the experimental sol–gel silica coating, we conducted an in vitro Salmonella typhimurium reverse mutation assay (Ames mutagenicity test), cytotoxicity tests, and in vivo oral mucous membrane irritation tests. When compared to the conventional tribochemical silica coating, the experimental sol–gel silica coating provided the same shear bond strength, higher silicon contents, and better durability. Moreover, we observed no apparent mutagenicity, cytotoxicity, or irritation in this study. Therefore, the sol–gel technique represents a promising method for producing silica coatings on zirconia. PMID:24179333

Marginal and Internal Discrepancies of Posterior Zirconia-Based Crowns Fabricated with Three Different CAD/CAM Systems Versus Metal-Ceramic.

PubMed

Ortega, Rocio; Gonzalo, Esther; Gomez-Polo, Miguel; Suárez, María J

2015-01-01

The aim of this study was to analyze the marginal and internal fit of metalceramic and zirconia-based crowns. Forty standardized steel specimens were prepared to receive posterior crowns and randomly divided into four groups (n = 10): (1) metal-ceramic, (2) NobelProcera Zirconia, (3) Lava Zirconia, and (4) VITA In-Ceram YZ. All crowns were cemented with glass-ionomer agent and sectioned buccolingually. A scanning electron microscope was used for measurements. Kruskal-Wallis and Wilcoxon signed rank test (α = .05) statistical analyses were conducted. Significant differences (P < .0001) in marginal discrepancies were observed between metal-ceramic and zirconia groups. No differences were found for the axial wall fit (P = .057). Significant differences were shown among the groups in discrepancies at the occlusal cusp (P = .0012) and at the fossa (P = .0062). No differences were observed between surfaces. All zirconia groups showed better values of marginal discrepancies than the metal-ceramic group. Procera Zirconia showed the lowest gaps.

Zirconia-coated carbonyl-iron-particle-based magnetorheological fluid for polishing optical glasses and ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafrir, Shai N.; Romanofsky, Henry J.; Skarlinski, Michael

2009-12-10

We report on magnetorheological finishing (MRF) spotting experiments performed on glasses and ceramics using a zirconia-coated carbonyl-iron (CI)-particle-based magnetorheological (MR) fluid. The zirconia-coated magnetic CI particles were prepared via sol-gel synthesis in kilogram quantities. The coating layer was {approx}50-100 nm thick, faceted in surface structure, and well adhered. Coated particles showed long-term stability against aqueous corrosion. ''Free'' nanocrystalline zirconia polishing abrasives were cogenerated in the coating process, resulting in an abrasive-charged powder for MRF. A viable MR fluid was prepared simply by adding water. Spot polishing tests were performed on a variety of optical glasses and ceramics over a periodmore » of nearly three weeks with no signs of MR fluid degradation or corrosion. Stable material removal rates and smooth surfaces inside spots were obtained.« less

Translucency of zirconia-based pressable ceramics with different core and veneer thicknesses.

PubMed

Jeong, Il-Do; Bae, So-Yeon; Kim, Dong-Yeon; Kim, Ji-Hwan; Kim, Woong-Chul

2016-06-01

Little information is available on the translucency of zirconia-based pressable ceramic restorations with a pressed ceramic veneer and zirconia core in various thickness combinations. The purpose of this in vitro study was to assess the translucency of 3 types of zirconia-based pressable ceramics for different core-veneer thickness combinations. A bilayered ceramic specimen was prepared with a pressable ceramic (IPS e.max Zirpress, Initial IQ, Rosetta UltraPress) veneer over a zirconia core (Zenostar Zr). Three groups of specimens (n=7) were formed with the following core+veneer thicknesses: 1 +0.5 mm, 0.7 +0.8 mm, and 0.5 +1 mm. To obtain consistent thickness and high translucency, all specimens were subjected to surface grinding with a grinding machine. To eliminate the effect of differences in roughness on the translucency, the surface roughness of the ground specimens was measured with a scanning profiler, and the consistency of these measured values was verified through statistical analysis. The luminous transmittance of the specimens was measured with a spectrophotometer. The effects of the pressable ceramic type and core-veneer thickness combination on transmittance were assessed using a 2-way ANOVA (α=.05). The consistency of the surface roughness among the tested specimens was confirmed using a 1-way ANOVA and the Tukey HSD post hoc test (P<.05). The luminous transmittance exhibited a statistically significant dependence on both the type of pressable ceramic and the core-veneer thickness combination (P<.05). The type of pressable ceramic and core-veneer thickness combination affected the translucency of the restoration. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chen W.; Smith, Hillary L.; Lan, Tian

2015-04-13

Inelastic neutron scattering measurements on monoclinic zirconia (ZrO 2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhatmore » more anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.« less

Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

PubMed

Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

2016-01-01

The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

Effect of the shades of background substructures on the overall color of zirconia-based all-ceramic crowns

PubMed Central

Tulapornchai, Chantana; Mamani, Jatuphol; Kamchatphai, Wannaporn; Thongpun, Noparat

2013-01-01

PURPOSE The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown. MATERIALS AND METHODS Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core build-up. The color measurements of all-ceramic crowns were made before try-in, before and after cementation. A repeated measure ANOVA was used for a statistical analysis of a color change of all-ceramic crowns at α=.05. Twenty four zirconia specimens, with different core thicknesses (0.4-1 mm) were also prepared to obtain the contrast ratio of zirconia materials after veneering. RESULTS L*, a*, and b* values of all-ceramic crowns cemented either on a metal cast post and core or on a prefabricated post did not show significant changes (P>.05). However, the slight color changes of zirconia crowns were detected and represented by ΔE*ab values, ranging from 1.2 to 3.1. The contrast ratios of zirconia specimens were 0.92-0.95 after veneering. CONCLUSION No significant differences were observed between the L*, a*, and b* values of zirconia crowns cemented either on a metal cast post and core or a prefabricated post and composite core. However, the color of a background substructure could affect the overall color of posterior zirconia restorations with clinically recommended core thickness according to ΔE*ab values. PMID:24049574

The bending stress distribution in bilayered and graded zirconia-based dental ceramics

PubMed Central

Fabris, Douglas; Souza, Júlio C.M.; Silva, Filipe S.; Fredel, Márcio; Mesquita-Guimarães, Joana; Zhang, Yu; Henriques, Bruno

2016-01-01

The purpose of this study was to evaluate the biaxial flexural stresses in classic bilayered and in graded zirconia-feldspathic porcelain composites. A finite element method and an analytical model were used to simulate the piston-on-ring test and to predict the biaxial stress distributions across the thickness of the bilayer and graded zirconia-feldspathic porcelain discs. An axisymmetric model and a flexure formula of Hsueh et al. were used in the FEM and analytical analysis, respectively. Four porcelain thicknesses were tested in the bilayered discs. In graded discs, continuous and stepwise transitions from the bottom zirconia layer to the top porcelain layer were studied. The resulting stresses across the thickness, measured along the central axis of the disc, for the bilayered and graded discs were compared. In bilayered discs, the maximum tensile stress decreased while the stress mismatch (at the interface) increased with the porcelain layer thickness. The optimized balance between both variables is achieved for a porcelain thickness ratio in the range of 0.30–0.35. In graded discs, the highest tensile stresses were registered for porcelain rich interlayers (p=0.25) whereas the zirconia rich ones (p=8) yield the lowest tensile stresses. In addition, the maximum stresses in a graded structure can be tailored by altering compositional gradients. A decrease in maximum stresses with increasing values of p (a scaling exponent in the power law function) was observed. Our findings showed a good agreement between the analytical and simulated models, particularly in the tensile region of the disc. Graded zirconia-feldspathic porcelain composites exhibited a more favourable stress distribution relative to conventional bilayered systems. This fact can significantly impact the clinical performance of zirconia-feldspathic porcelain prostheses, namely reducing the fracture incidence of zirconia and the chipping and delamination of porcelain. PMID:28104926

Zirconia ceramics for excess weapons plutonium waste

NASA Astrophysics Data System (ADS)

Gong, W. L.; Lutze, W.; Ewing, R. C.

2000-01-01

We synthesized a zirconia (ZrO 2)-based single-phase ceramic containing simulated excess weapons plutonium waste. ZrO 2 has large solubility for other metallic oxides. More than 20 binary systems A xO y-ZrO 2 have been reported in the literature, including PuO 2, rare-earth oxides, and oxides of metals contained in weapons plutonium wastes. We show that significant amounts of gadolinium (neutron absorber) and yttrium (additional stabilizer of the cubic modification) can be dissolved in ZrO 2, together with plutonium (simulated by Ce 4+, U 4+ or Th 4+) and impurities (e.g., Ca, Mg, Fe, Si). Sol-gel and powder methods were applied to make homogeneous, single-phase zirconia solid solutions. Pu waste impurities were completely dissolved in the solid solutions. In contrast to other phases, e.g., zirconolite and pyrochlore, zirconia is extremely radiation resistant and does not undergo amorphization. Baddeleyite (ZrO 2) is suggested as the natural analogue to study long-term radiation resistance and chemical durability of zirconia-based waste forms.

Preliminary Evaluations of Polymer-based Lithium Battery Electrolytes Under Development for the Polymer Electrolyte Rechargeable Systems Program

NASA Technical Reports Server (NTRS)

Manzo, Michelle A.; Bennett, William R.

2003-01-01

A component screening facility has been established at The NASA Glenn Research Center (GRC) to evaluate candidate materials for next generation, lithium-based, polymer electrolyte batteries for aerospace applications. Procedures have been implemented to provide standardized measurements of critical electrolyte properties. These include ionic conductivity, electronic resistivity, electrochemical stability window, cation transference number, salt diffusion coefficient and lithium plating efficiency. Preliminary results for poly(ethy1ene oxide)-based polymer electrolyte and commercial liquid electrolyte are presented.

Towards long lasting zirconia-based composites for dental implants: Transformation induced plasticity and its consequence on ceramic reliability.

PubMed

Reveron, Helen; Fornabaio, Marta; Palmero, Paola; Fürderer, Tobias; Adolfsson, Erik; Lughi, Vanni; Bonifacio, Alois; Sergo, Valter; Montanaro, Laura; Chevalier, Jérôme

2017-01-15

Zirconia-based composites were developed through an innovative processing route able to tune compositional and microstructural features very precisely. Fully-dense ceria-stabilized zirconia ceramics (84vol% Ce-TZP) containing equiaxed alumina (8vol%Al 2 O 3 ) and elongated strontium hexa-aluminate (8vol% SrAl 12 O 19 ) second phases were obtained by conventional sintering. This work deals with the effect of the zirconia stabilization degree (CeO 2 in the range 10.0-11.5mol%) on the transformability and mechanical properties of Ce-TZP-Al 2 O 3 -SrAl 12 O 19 materials. Vickers hardness, biaxial flexural strength and Single-edge V-notched beam tests revealed a strong influence of ceria content on the mechanical properties. Composites with 11.0mol% CeO 2 or above exhibited the classical behaviour of brittle ceramics, with no apparent plasticity and very low strain to failure. On the contrary, composites with 10.5mol% CeO 2 or less showed large transformation-induced plasticity and almost no dispersion in strength data. Materials with 10.5mol% of ceria showed the highest values in terms of biaxial bending strength (up to 1.1GPa) and fracture toughness (>10MPa√m). In these ceramics, as zirconia transformation precedes failure, the Weibull modulus was exceptionally high and reached a value of 60, which is in the range typically reported for metals. The results achieved demonstrate the high potential of using these new strong, tough and stable zirconia-based composites in structural biomedical applications. Yttria-stabilized (Y-TZP) zirconia ceramics are increasingly used for developing metal-free restorations and dental implants. Despite their success related to their excellent mechanical resistance, Y-TZP can undergo Low Temperature Degradation which could be responsible for restoration damage or even worst the failure of the implant. Current research is focusing on strategies to improve the LTD resistance of Y-TZP or to develop alternative composites with better

Enhanced performance of ultracapacitors using redox additive-based electrolytes

NASA Astrophysics Data System (ADS)

Jain, Dharmendra; Kanungo, Jitendra; Tripathi, S. K.

2018-05-01

Different concentrations of potassium iodide (KI) as redox additive had been added to 1 M sulfuric acid (H2SO4) electrolyte with an aim of enhancing the capacitance and energy density of ultracapacitors via redox reactions at the interfaces of electrode-electrolyte. Ultracapacitors were fabricated using chemically treated activated carbon as electrode with H2SO4 and H2SO4-KI as an electrolyte. The electrochemical performances of fabricated supercapacitors were investigated by impedance spectroscopy, cyclic voltammetry and charge-discharge techniques. The maximum capacitance ` C' was observed with redox additives-based electrolyte system comprising 1 M H2SO4-0.3 M KI (1072 F g- 1), which is very much higher than conventional 1 M H2SO4 (61.3 F g- 1) aqueous electrolyte-based ultracapacitors. It corresponds to an energy density of 20.49 Wh kg- 1 at 2.1 A g- 1 for redox additive-based electrolyte, which is six times higher as compared to that of pristine electrolyte (1 M H2SO4) having energy density of only 3.36 Wh kg- 1. The temperature dependence behavior of fabricated cell was also analyzed, which shows increasing pattern in its capacitance values in a temperature range of 5-70 °C. Under cyclic stability test, redox electrolyte-based system shows almost 100% capacitance retention up to 5000 cycles and even more. For comparison, ultracapacitors based on polymer gel electrolyte polyvinyl alcohol (PVA) (10 wt%)—{H2SO4 (1 M)-KI (0.3 M)} (90 wt%) have been fabricated and characterized with the same electrode materials.

Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function.

PubMed

Oilo, Marit; Hardang, Anne D; Ulsund, Amanda H; Gjerdet, Nils R

2014-06-01

Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation. © 2014 Eur J Oral Sci.

Sulfone-based electrolytes for aluminium rechargeable batteries.

PubMed

Nakayama, Yuri; Senda, Yui; Kawasaki, Hideki; Koshitani, Naoki; Hosoi, Shizuka; Kudo, Yoshihiro; Morioka, Hiroyuki; Nagamine, Masayuki

2015-02-28

Electrolyte is a key material for success in the research and development of next-generation rechargeable batteries. Aluminium rechargeable batteries that use aluminium (Al) metals as anode materials are attractive candidates for next-generation batteries, though they have not been developed yet due to the lack of practically useful electrolytes. Here we present, for the first time, non-corrosive reversible Al electrolytes working at room temperature. The electrolytes are composed of aluminium chlorides, dialkylsulfones, and dilutants, which are realized by the identification of electrochemically active Al species, the study of sulfone dependences, the effects of aluminium chloride concentrations, dilutions and their optimizations. The characteristic feature of these materials is the lower chloride concentrations in the solutions than those in the conventional Al electrolytes, which allows us to use the Al metal anodes without corrosions. We anticipate that the sulfone-based electrolytes will open the doors for the research and development of Al rechargeable batteries.

pH control of the structure, composition, and catalytic activity of sulfated zirconia

NASA Astrophysics Data System (ADS)

Ivanov, Vladimir K.; Baranchikov, Alexander Ye.; Kopitsa, Gennady P.; Lermontov, Sergey A.; Yurkova, Lyudmila L.; Gubanova, Nadezhda N.; Ivanova, Olga S.; Lermontov, Anatoly S.; Rumyantseva, Marina N.; Vasilyeva, Larisa P.; Sharp, Melissa; Pranzas, P. Klaus; Tretyakov, Yuri D.

2013-02-01

We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to ˜2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to ˜80 m2/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions.

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

NASA Astrophysics Data System (ADS)

Marr, Michael; Kesler, Olivera

2012-12-01

Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

Effects of cementation surface modifications on fracture resistance of zirconia.

PubMed

Srikanth, Ramanathan; Kosmac, Tomaz; Della Bona, Alvaro; Yin, Ling; Zhang, Yu

2015-04-01

To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia. Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending. Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength. While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effects of cementation surface modifications on fracture resistance of zirconia

PubMed Central

Srikanth, Ramanathan; Kosmac, Tomaz; Bona, Alvaro Della; Yin, Ling; Zhang, Yu

2015-01-01

Objectives To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia. Methods Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 mm or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2 mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending. Results Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength. Significance While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia. PMID:25687628

Evaluation of participants' perception and taste thresholds with a zirconia palatal plate.

PubMed

Wada, Takeshi; Takano, Tomofumi; Tasaka, Akinori; Ueda, Takayuki; Sakurai, Kaoru

2016-10-01

Zirconia and cobalt-chromium can withstand a similar degree of loading. Therefore, using a zirconia base for removable dentures could allow the thickness of the palatal area to be reduced similarly to metal base dentures. We hypothesized that zirconia palatal plate for removable dentures provides a high level of participants' perception without influencing taste thresholds. The purpose of this study was to evaluate the participants' perception and taste thresholds of zirconia palatal plate. Palatal plates fabricated using acrylic resin, zirconia, and cobalt-chromium alloy were inserted into healthy individuals. Taste thresholds were investigated using the whole-mouth gustatory test, and participants' perception was evaluated using the 100-mm visual analog scale to assess the ease of pronunciation, ease of swallowing, sensation of temperature, metallic taste, sensation of foreign body, subjective sensory about weight, adhesiveness of chewing gum, and general satisfaction. For the taste thresholds, no significant differences were noted in sweet, salty, sour, bitter, or umami tastes among participants wearing no plate, or the resin, zirconia, and metal plates. Speech was easier and foreign body sensation was lower with the zirconia plate than with the resin plate. Evaluation of the adhesiveness of chewing gum showed that chewing gum does not readily adhere to the zirconia plate in comparison with the metal plate. The comprehensive participants' perception of the zirconia plate was evaluated as being superior to the resin plate. A zirconia palatal plate provides a high level of participants' perception without influencing taste thresholds. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Zirconia-based dental crown to support a removable partial denture: a three-dimensional finite element analysis using contact elements and micro-CT data.

PubMed

Rocha, Eduardo Passos; Anchieta, Rodolfo Bruniera; de Almeida, Erika Oliveira; Freitas, Amilcar Chagas; Martini, Ana Paula; Sotto-Maior, Bruno Sales; Luersen, Marco Antonio; Ko, Ching Chang

2015-01-01

Veneer fracture is the most common complication in zirconia-based restorations. The aim of this study was to evaluate the mechanical behavior of a zirconia-based crown in a lower canine tooth supporting removable partial denture (RPD) prosthesis, varying the bond quality of the veneer/coping interface. Microtomography (μCT) data of an extracted left lower canine were used to build the finite element model (M) varying the core material (gold core - MAu; zirconia core - MZi) and the quality of the veneer/core interface (complete bonded - MZi; incomplete bonded - MZi-NL). The incomplete bonding condition was only applied for zirconia coping by using contact elements (Target/Contact) with 0.3 frictional coefficients. Stress fields were obtained using Ansys Workbench 10.0. The loading condition (L = 1 N) was vertically applied at the base of the RPD prosthesis metallic support towards the dental apex. Maximum principal (σmax) and von Mises equivalent (σvM) stresses were obtained. The σmax (MPa) for the bonded condition was similar between gold and zirconia cores (MAu, 0.42; MZi, 0.40). The incomplete bonded condition (MZi-NL) raised σmax in the veneer up to 800% (3.23 MPa) in contrast to the bonded condition. The peak of σvM increased up to 270% in the MZi-NL. The incomplete bond condition increasing the stress in the veneer/zirconia interface.

Handheld Microneedle-Based Electrolyte Sensing Platform.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Philip R.; Rivas, Rhiana; Johnson, David

2015-11-01

Sandia National Laboratories will provide technical assistance, within time and budget, to Requester on testing and analyzing a microneedle-based electrolyte sensing platform. Hollow microneedles will be fabricated at Sandia and integrated with a fluidic chip using plastic laminate prototyping technology available at Sandia. In connection with commercial ion selective electrodes the sensing platform will be tested for detection of electrolytes (sodium and/or potassium) within physiological relevant concent ration ranges.

DNA Based Electrolyte/Separator for Lithium Battery Application (Postprint)

DTIC Science & Technology

2015-10-07

Lithium - ion or sodium- ion ) batteries and the second are the gel polymer electrolyte (GPE) metal- ion batteries also known as metal- ion polymer...AFRL-RX-WP-JA-2016-0302 DNA BASED ELECTROLYTE/SEPARATOR FOR LITHIUM BATTERY APPLICATION (POSTPRINT) Jitendra Kumar1, Fahima...BASED ELECTROLYTE/SEPARATOR FOR LITHIUM BATTERY APPLICATION (POSTPRINT) 5a. CONTRACT NUMBER FA8650-15-D-5405-0001 5b. GRANT NUMBER 5c. PROGRAM

Research on surface modification of nano-zirconia

NASA Astrophysics Data System (ADS)

Chen, Wen; Zhang, Cun-Lin; Yang, Xiao-Yi

2005-02-01

The mechanisms about the aggregation and dispersibility of nano-zirconia were analyzed in detail. And nano-zirconia powders which were surface-modified with silane coupling reagent WD70 were prepared in order to disperse homogeneously in ethanol in this investigation. The grain size and grain phase of nano-zirconia were obtained by XRD. Research and characterization on the structure and surface characteristic of surface-modified nano-zirconia were achieved by XPS, TG-DSC, TEM and FT-IR. The results given by FT-IR and XPS showed WD70 was jointed on the surface of nano-zirconia through both physical adsorption and chemical binding after the de-methanol reaction between the methoxyl groups of WD70 and the hydroxy groups on the surface of nano-zirconia. And the corresponding model of surface-modified nano-zirconia was given. The images provided by TEM presented intuitionistic effect of surface modification on the dispersibility of nano-zirconia in ethanol. And TG-DSC analysis ascertained the amount of WD70 that was jointed on the surface of nano-zirconia and the amount was about 6.21 percent.

HOT ELUENT CAPILLARY LIQUID CHROMATOGRAPHY USING ZIRCONIA AND TITANIA BASED STATIONARY PHASES. (R825344)

EPA Science Inventory

Abstract

High speed capillary liquid chromatographic separations using a simple home made system constructed from readily available inexpensive components have been studied. Using thermally stable zirconia and titania based packing, the separation of eight alkylbenzene...

Innovations in bonding to zirconia based ceramics: Part III. Phosphate monomer resin cements.

PubMed

Mirmohammadi, Hesam; Aboushelib, Moustafa N M; Salameh, Ziad; Feilzer, Albert J; Kleverlaan, Cornelis J

2010-08-01

To compare the bond strength values and the ranking order of three phosphate monomer containing resin cements using microtensile (microTBS) and microshear (microSBS) bond strength tests. Zirconia discs (Procera Zirconia) were bonded to resin composite discs (Filtek Z250) using three different cements (Panavia F 2.0, RelyX UniCem, and Multilink). Two bond strength tests were used to determine zirconia resin bond strength; microtensile bond strength test (microTBS) and microshear bond strength test (microSBS). Ten specimens were tested for each group (n=10). Two-way analysis of variance (ANOVA) was used to analyze the data (alpha=0.05). There were statistical significant differences in bond strength values and in the ranking order obtained using the two test methods. microTBS reported significant differences in bond strength values, whereas microSBS failed to detect such effect. Both Multilink and Panavia demonstrated basically cohesive failure in the resin cement while RelyX UniCem demonstrated interfacial failure. Based on the findings of this study, the data obtained using either microTBS or microSBS could not be directly compared. microTBS was more sensitive to material differences compared to microSBS which failed to detect such differences. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Synthesis and characterization of mesoporous zirconia and aluminated mesoporous zirconia

NASA Astrophysics Data System (ADS)

Zhao, Elizabeth Sun

Synthesis of mesoporous zirconia has been performed by slowly hydrolyzing zirconium propoxide in the presence of anionic surfactants: namely, dodecyl phosphate or sulfate (P12 and Sf12) and hexadecyl sulfonate (So16) The zirconia. outgassed at 140--150°C has T-plot surface areas higher than 400 M2/g. This outgassing does not remove the surfactant. After calcination in air at 500°C and combustion of the surfactant, the mesoporous volume is reduced by a factor of about 2, whereas the pore wall material crystallizes in the tetragonal phase. The high-resolution electron microscopic study reveals the presence of a disorganized network of polygonal pores structure. It is suggested that the chemistry of the hydrolysis solution is instrumental in determining the pore structure. A schematic model in which the surfactant is a scaffold component is suggested in order to explain these results and the fixation of PO4, or SO4 in the walls may help to preserve the porous structure. It is very different from the templating mechanism. From the density obtained from phase transition temperature, and from the mesoporous volume (N2 adsorption), the thickness of the wall can be calculated as well as the pseudo-length of the pores. From the thickness, the T-plot area can be recalculated and agrees well with the measured T-plot surface area for the sample calcined at 500°C. Around 900°C, the walls become thicker and crystallizes into monoclinic zirconia without pore structure. In order to try to modify, the acidity of the mesoporous sulfated and oxo-phosphated zirconia, they were doped with aluminum. The sulfated zirconia only has a coating layer of amorphous alumina, while the phosphated zirconia has aluminum in the lattice and the alumina coat. A maximum ratio of Al/Zr ˜ 0.04 can be reached in the lattice. The introduction of aluminum into the lattice prevents the crystallization of the oxo-phosphate at 900°C, and helps to preserve the surface area and porosity of the sulfated

Electrochemical performance of solid oxide fuel cells having electrolytes made by suspension and solution precursor plasma spraying

NASA Astrophysics Data System (ADS)

Marr, M.; Kuhn, J.; Metcalfe, C.; Harris, J.; Kesler, O.

2014-01-01

Yttria-stabilized zirconia (YSZ) electrolytes were deposited by suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). The electrolytes were evaluated for permeability, microstructure, and electrochemical performance. With SPS, three different suspensions were tested to explore the influence of powder size distribution and liquid properties. Electrolytes made from suspensions of a powder with d50 = 2.6 μm were more gas-tight than those made from suspensions of a powder with d50 = 0.6 μm. A peak open circuit voltage of 1.00 V was measured at 750 °C with a cell with an electrolyte made from a suspension of d50 = 2.6 μm powder. The use of a flammable suspension liquid was beneficial for improving electrolyte conductivity when using lower energy plasmas, but the choice of liquid was less important when using higher energy plasmas. With SPPS, peak electrolyte conductivities were comparable to the peak conductivities of the SPS electrolytes. However, leak rates through the SPPS electrolytes were higher than those through the electrolytes made from suspensions of d50 = 2.6 μm powder. The electrochemical test data on SPPS electrolytes are the first reported in the literature.

Fracture strength of zirconia implant abutments on narrow diameter implants with internal and external implant abutment connections: A study on the titanium resin base concept.

PubMed

Sailer, Irena; Asgeirsson, Asgeir G; Thoma, Daniel S; Fehmer, Vincent; Aspelund, Thor; Özcan, Mutlu; Pjetursson, Bjarni E

2018-04-01

There is limited knowledge regarding the strength of zirconia abutments with internal and external implant abutment connections and zirconia abutments supported by a titanium resin base (Variobase, Straumann) for narrow diameter implants. To compare the fracture strength of narrow diameter abutments with different types of implant abutment connections after chewing simulation. Hundred and twenty identical customized abutments with different materials and implant abutment connections were fabricated for five groups: 1-piece zirconia abutment with internal connection (T1, Cares-abutment-Straumann BL-NC implant, Straumann Switzerland), 1-piece zirconia abutment with external hex connection (T2, Procera abutment-Branemark NP implant, Nobel Biocare, Sweden), 2-piece zirconia abutments with metallic insert for internal connection (T3, Procera abutment-Replace NP implant, Nobel Biocare), 2-piece zirconia abutment on titanium resin base (T4, LavaPlus abutment-VarioBase-Straumann BL-NC implant, 3M ESPE, Germany) and 1-piece titanium abutment with internal connection (C, Cares-abutment-Straumann BL-NC implant, Straumann, Switzerland). All implants had a narrow diameter ranging from 3.3 to 3.5 mm. Sixty un-restored abutments and 60 abutments restored with glass-ceramic crowns were tested. Mean bending moments were compared using ANOVA with p-values adjusted for multiple comparisons using Tukey's procedure. The mean bending moments were 521 ± 33 Ncm (T4), 404 ± 36 Ncm (C), 311 ± 106 Ncm (T1) 265 ± 22 Ncm (T3) and 225 ± 29 (T2) for un-restored abutments and 278 ± 84 Ncm (T4), 302 ± 170 Ncm (C), 190 ± 55 Ncm (T1) 80 ± 102 Ncm (T3) and 125 ± 57 (T2) for restored abutments. For un-restored abutments, C and T4 had similar mean bending moments, significantly higher than those of the three other groups (p < .05). Titanium abutments (C) had significantly higher bending moments than identical zirconia abutments (T1) (p < .05). Zirconia

Assessment and comparison of retention of zirconia copings luted with different cements onto zirconia and titanium abutments: An in vitro study

PubMed Central

Menon, Neelima Sreekumar; Kumar, G. P. Surendra; Jnanadev, K. R.; Satish Babu, C. L.; Shetty, Shilpa

2016-01-01

Aim: The purpose of this in vitro study was to assess and compare the retention of zirconia copings luted with different luting agents onto zirconia and titanium abutments. Materials and Methods: Titanium and zirconia abutments were torqued at 35 N/cm onto implant analogs. The samples were divided into two groups: Group A consisted of four titanium abutments and 32 zirconia copings and Group B consisted of four zirconia abutments and 32 zirconia copings and four luting agents were used. The cemented copings were subjected to tensile dislodgement forces and subjected to ANOVA test. Results: Zirconia abutments recorded a higher mean force compared to titanium. Among the luting agents, resin cement recorded the highest mean force followed by zinc phosphate, glass ionomer, and noneugenol zinc oxide cement, respectively. Conclusion: Highest mean retention was recorded for zirconia implant abutments compared to titanium abutments when luted with zirconia copings. PMID:27141162

Influence of CAD/CAM systems and cement selection on marginal discrepancy of zirconia-based ceramic crowns.

PubMed

Martínez-Rus, Francisco; Suárez, María J; Rivera, Begoña; Pradíes, Guillermo

2012-04-01

To analyze the effect of ceramic manufacturing technique and luting cement selection on the marginal adaptation of zirconium oxide-based all-ceramic crowns. An extracted mandibular first premolar was prepared for a complete coverage restoration and subsequently duplicated 40 times in a liquid crystal polymer (LCP). All-ceramic crowns (n = 10) were fabricated on LCP models using the following systems: glass-infiltrated zirconia-toughened alumina (In-Ceram Zirconia) and yttrium cation-doped tetragonal zirconia polycrystals (In-Ceram YZ, Cercon, and Procera Zirconia). The restorations (n = 5) were cemented on their respective dies with glass-ionomer cement (Ketac Cem Aplicap) and resin cement (Panavia 21). The absolute marginal discrepancy of the crowns was measured before and after cementation by scanning electronic microscopy at 160 points along the circumferential margin. The data were analyzed using one-way ANOVA for repeated measures and for independent samples, Scheffé's multiple range post hoc test, and Student's t-test (alpha = 0.05). There were statistical differences in the mean marginal openings among the four all-ceramic systems before and after luting (P < 0.0001). The Procera restorations had the lowest pre- and post-cementation values (P < 0.0001). A significant increase in the marginal gap size caused by luting media occurred in all tested groups (P < 0.0001). Resin cement resulted in larger marginal discrepancies than glass-ionomer cement (P < 0.0001).

Purely electronic mechanism of electrolyte gating of indium tin oxide thin films

DOE PAGES

Leng, X.; Bozovic, I.; Bollinger, A. T.

2016-08-10

Epitaxial indium tin oxide films have been grown on both LaAlO 3 and yttria-stabilized zirconia substrates using RF magnetron sputtering. Electrolyte gating causes a large change in the film resistance that occurs immediately after the gate voltage is applied, and shows no hysteresis during the charging/discharging processes. When two devices are patterned next to one another and the first one gated through an electrolyte, the second one shows no changes in conductance, in contrast to what happens in materials (like tungsten oxide) susceptible to ionic electromigration and intercalation. These findings indicate that electrolyte gating in indium tin oxide triggers amore » pure electronic process (electron depletion or accumulation, depending on the polarity of the gate voltage), with no electrochemical reactions involved. Electron accumulation occurs in a very thin layer near the film surface, which becomes highly conductive. These results contribute to our understanding of the electrolyte gating mechanism in complex oxides and may be relevant for applications of electric double layer transistor devices.« less

Optimized Carbonate and Ester-Based Li-Ion Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall; Bugga, Ratnakumar

2008-01-01

To maintain high conductivity in low temperatures, electrolyte co-solvents have been designed to have a high dielectric constant, low viscosity, adequate coordination behavior, and appropriate liquid ranges and salt solubilities. Electrolytes that contain ester-based co-solvents in large proportion (greater than 50 percent) and ethylene carbonate (EC) in small proportion (less than 20 percent) improve low-temperature performance in MCMB carbon-LiNiCoO2 lithium-ion cells. These co-solvents have been demonstrated to enhance performance, especially at temperatures down to 70 C. Low-viscosity, ester-based co-solvents were incorporated into multi-component electrolytes of the following composition: 1.0 M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (1:1:8 volume percent) [where X = methyl butyrate (MB), ethyl butyrate EB, methyl propionate (MP), or ethyl valerate (EV)]. These electrolyte formulations result in improved low-temperature performance of lithium-ion cells, with dramatic results at temperatures below 40 C.

Electrochemical testing of industrially produced PEO-based polymer electrolytes

NASA Astrophysics Data System (ADS)

Appetecchi, G. B.; Alessandrini, F.; Duan, R. G.; Arzu, A.; Passerini, S.

The present report describes the results of the electrochemical tests performed on polyethyleneoxide-based polymer electrolyte thin films industrially manufactured by blown-extrusion. The polymer electrolyte composition was PEO 20 LiCF 3SO 3: 16.7% γLiAlO 2. The polymer electrolyte film was tested to evaluate the ionic conductivity as well as the interfacial properties with lithium metal anodes. The work was developed within the advanced lithium polymer electrolyte (ALPE) project, an Italian project devoted to the realization of lithium polymer batteries for electric vehicle applications, in collaboration with Union Carbide.

Ionic-Liquid-Based Polymer Electrolytes for Battery Applications.

PubMed

Osada, Irene; de Vries, Henrik; Scrosati, Bruno; Passerini, Stefano

2016-01-11

The advent of solid-state polymer electrolytes for application in lithium batteries took place more than four decades ago when the ability of polyethylene oxide (PEO) to dissolve suitable lithium salts was demonstrated. Since then, many modifications of this basic system have been proposed and tested, involving the addition of conventional, carbonate-based electrolytes, low molecular weight polymers, ceramic fillers, and others. This Review focuses on ternary polymer electrolytes, that is, ion-conducting systems consisting of a polymer incorporating two salts, one bearing the lithium cation and the other introducing additional anions capable of plasticizing the polymer chains. Assessing the state of the research field of solid-state, ternary polymer electrolytes, while giving background on the whole field of polymer electrolytes, this Review is expected to stimulate new thoughts and ideas on the challenges and opportunities of lithium-metal batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon dioxide electrolysis with solid oxide electrolyte cells for oxygen recovery in life support systems

NASA Technical Reports Server (NTRS)

Isenberg, Arnold O.; Cusick, Robert J.

1988-01-01

The direct electrochemical reduction of carbon dioxide (CO2) is achieved without catalysts and at sufficiently high temperatures to avoid carbon formation. The tubular electrolysis cell consists of thin layers of anode, electrolyte, cathode and cell interconnection. The electrolyte is made from yttria-stabilized zirconia which is an oxygen ion conductor at elevated temperatures. Anode and cell interconnection materials are complex oxides and are electronic conductors. The cathode material is a composite metal-ceramic structure. Cell performance characteristics have been determined using varying feed gas compositions and degrees of electrochemical decomposition. Cell test data are used to project the performance of a three-person CO2-electrolysis breadboard system.

Biological and nano-indentation properties of polybenzoxazine-based composites reinforced with zirconia particles as a novel biomaterial.

PubMed

Lotfi, L; Javadpour, J; Naimi-Jamal, M R

2018-01-01

The biological and mechanical properties of substances are relevant to their application as biomaterials and there are many efforts to enhance biocompatibility and mechanical properties of bio-medical materials. In this study, to achieve a low rate of shrinkage during polymerization, good mechanical properties, and excellent biocompatibility, benzoxazine based composites were synthesized. Benzoxazine monomer was synthesized using a solventless method. FTIR and DSC analysis were carried out to determine the appropriate polymerization temperature. The low viscosity of the benzoxazine monomer at 70°C attract us to use in situ polymerization after high speed ball milling of the benzoxazine and it mixture with different weight fractions of zirconia particles. Dispersion and adhesion between the ceramic and polymer components were evaluate by SEM. To evaluate the biological properties and toxicity of the polybenzoxazine-based composite samples reinforced with zirconia particles, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay was conducted. The micromechanical properties of each composite were evaluated by more than 20 nanoindentation tests and 3 nanoscratching tests. Surface topography of scratched regions was investigated using Atomic Force Microscopy. Shrinkage was simulated by Materials Studio software. SEM images showed good dispersion and adhesion between the ceramic and polymer components. Biocompatibility assay showed excellent in vitro biocompatibility. Nano-indentation force-displacement curves showed matrix, reinforcement and interphase regions in specimens and excellent homogeneity in mechanical properties. The nanoindentation results showed that the addition of zirconia particles to the polybenzoxazine matrix increased the modulus and hardness of the neat polybenzoxazine; however, by adding more than an optimum level of reinforcement particles, the mechanical properties decreased due to the agglomeration of reinforcement particles and

Stock Versus CAD/CAM Customized Zirconia Implant Abutments - Clinical and Patient-Based Outcomes in a Randomized Controlled Clinical Trial.

PubMed

Schepke, Ulf; Meijer, Henny J A; Kerdijk, Wouter; Raghoebar, Gerry M; Cune, Marco

2017-02-01

Single-tooth replacement often requires a prefabricated dental implant and a customized crown. The benefits of individualization of the abutment remain unclear. This randomized controlled clinical trial aims to study potential benefits of individualization of zirconia implant abutments with respect to preservation of marginal bone level and several clinical and patient-based outcome measures. Fifty participants with a missing premolar were included and randomly assigned to standard (ZirDesign, DentsplySirona Implants, Mölndal, Sweden) or computer aided design/computer aided manufacturing (CAD/CAM) customized (Atlantis, DentsplySirona Implants, Mölndal, Sweden) zirconia abutment therapy. Peri-implant bone level (primary outcome), Plaque-index, calculus formation, bleeding on probing, gingiva index, probing pocket depth, recession, appearance of soft tissues and patients' contentment were assessed shortly after placement and one year later. No implants were lost and no complications related to the abutments were observed. Statistically significant differences between stock and CAD/CAM customized zirconia abutments could not be demonstrated for any of the operationalized variables. The use of a CAD/CAM customized zirconia abutment in single tooth replacement of a premolar is not associated with an improvement in clinical performance or patients' contentment when compared to the use of a stock zirconia abutment. © 2016 The Authors. Clinical Implant Dentistry and Related Research Published by Wiley Periodicals, Inc.

Halogen-free boron based electrolyte solution for rechargeable magnesium batteries

NASA Astrophysics Data System (ADS)

Zhu, Jinjie; Guo, Yongsheng; Yang, Jun; Nuli, Yanna; Zhang, Fan; Wang, Jiulin; Hirano, Shin-ichi

2014-02-01

All halogen containing electrolytes for Mg battery are apt to corrode conventional metal current collectors. In this paper, a new type of halogen-free boron based electrolyte (Mg[Mes3BPh]2/THF) is designed and prepared. Electrochemical tests show that this electrolyte system possesses high ion conductivity (1.5 × 10-3 S cm-1) and good Mg deposition-dissolution reversibility. More importantly, the same electrochemical window (2.6 V vs. Mg RE) of the electrolyte on Pt and stainless steel electrodes indicates that halogen-free electrolyte indeed lessens the corrosion to conventional metal current collectors. The surface morphologies of stainless steel, aluminum and copper are further observed after their anodic potentiostatic polarization in 0.25 mol L-1 Mg[Mes3BPh]2/THF electrolyte solution for 2 days. A comparison with halogen containing electrolytes proves that the presence of halogen in electrolyte is the reason for corrosion. This work provides a stepping stone for developing new halogen-free electrolyte systems for rechargeable Mg batteries.

Stock Versus CAD/CAM Customized Zirconia Implant Abutments – Clinical and Patient‐Based Outcomes in a Randomized Controlled Clinical Trial

PubMed Central

Meijer, Henny J.A.; Kerdijk, Wouter; Raghoebar, Gerry M.; Cune, Marco

2016-01-01

Abstract Background Single‐tooth replacement often requires a prefabricated dental implant and a customized crown. The benefits of individualization of the abutment remain unclear. Purpose This randomized controlled clinical trial aims to study potential benefits of individualization of zirconia implant abutments with respect to preservation of marginal bone level and several clinical and patient‐based outcome measures. Material and Methods Fifty participants with a missing premolar were included and randomly assigned to standard (ZirDesign, DentsplySirona Implants, Mölndal, Sweden) or computer aided design/computer aided manufacturing (CAD/CAM) customized (Atlantis, DentsplySirona Implants, Mölndal, Sweden) zirconia abutment therapy. Peri‐implant bone level (primary outcome), Plaque‐index, calculus formation, bleeding on probing, gingiva index, probing pocket depth, recession, appearance of soft tissues and patients' contentment were assessed shortly after placement and one year later. Results No implants were lost and no complications related to the abutments were observed. Statistically significant differences between stock and CAD/CAM customized zirconia abutments could not be demonstrated for any of the operationalized variables. Conclusion The use of a CAD/CAM customized zirconia abutment in single tooth replacement of a premolar is not associated with an improvement in clinical performance or patients' contentment when compared to the use of a stock zirconia abutment. PMID:27476829

Solid oxide fuel cells with apatite-type lanthanum silicate-based electrolyte films deposited by radio frequency magnetron sputtering

NASA Astrophysics Data System (ADS)

Liu, Yi-Xin; Wang, Sea-Fue; Hsu, Yung-Fu; Wang, Chi-Hua

2018-03-01

In this study, solid oxide fuel cells (SOFCs) containing high-quality apatite-type magnesium doped lanthanum silicate-based electrolyte films (LSMO) deposited by RF magnetron sputtering are successfully fabricated. The LSMO film deposited at an Ar:O2 ratio of 6:4 on an anode supported NiO/Sm0.2Ce0·8O2-δ (SDC) substrate followed by post-annealing at 1000 °C reveals a uniform and dense c-axis oriented polycrystalline structure, which is well adhered to the anode substrate. A composite SDC/La0·6Sr0·4Co0·2Fe0·8O3-δ cathode layer is subsequently screen-printed on the LSMO deposited anode substrate and fired. The SOFC fabricated with the LSMO film exhibits good mechanical integrity. The single cell with the LSMO layer of ≈2.8 μm thickness reports a total cell resistance of 1.156 and 0.163 Ωcm2, open circuit voltage of 1.051 and 0.982 V, and maximum power densities of 0.212 and 1.490 Wcm-2 at measurement temperatures of 700 and 850 °C, respectively, which are comparable or superior to those of previously reported SOFCs with yttria stabilized zirconia electrolyte films. The results of the present study demonstrate the feasibility of deposition of high-quality LSMO films by RF magnetron sputtering on NiO-SDC anode substrates for the fabrication of SOFCs with good cell performance.

Adhesion/cementation to zirconia and other non-silicate ceramics: Where are we now?

PubMed Central

Thompson, Jeffrey Y; Stoner, Brian R.; Piascik, Jeffrey R.; Smith, Robert

2010-01-01

Non-silicate ceramics, especially zirconia, have become a topic of great interest in the field of prosthetic and implant dentistry. A clinical problem with use of zirconia-based components is the difficulty in achieving suitable adhesion with intended synthetic substrates or natural tissues. Traditional adhesive techniques used with silica-based ceramics do not work effectively with zirconia. Currently, several technologies are being utilized clinically to address this problem, and other approaches are under investigation. Most focus on surface modification of the inert surfaces of high strength ceramics. The ability to chemically functionalize the surface of zirconia appears to be critical in achieving adhesive bonding. This review will focus on currently available approaches as well as new advanced technologies to address this problem. PMID:21094526

CAD/CAM ZIRCONIA VS. SLIP-CAST GLASS-INFILTRATED ALUMINA/ZIRCONIA ALL-CERAMIC CROWNS: 2-YEAR RESULTS OF A RANDOMIZED CONTROLLED CLINICAL TRIAL

PubMed Central

Çehreli, Murat Cavit; Kökat, Ali Murat; Akça, Kivanç

2009-01-01

The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73%) and Cercon® Zirconia (80%) restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66%) than Cercon® Zirconia (26%) restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05). This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone. PMID:19148406

Biaxial flexural strength of bilayered zirconia using various veneering ceramics

PubMed Central

Chantranikul, Natravee

2015-01-01

PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength. PMID:26576251

Development of zirconia based phosphors for application in lighting and as luminescent bioprobes =

NASA Astrophysics Data System (ADS)

Soares, Maria Rosa Nunes

The strong progress evidenced in photonic and optoelectronic areas, accompanied by an exponential development in the nanoscience and nanotechnology, gave rise to an increasing demand for efficient luminescent materials with more and more exigent characteristics. In this field, wide band gap hosts doped with lanthanide ions represent a class of luminescent materials with a strong technological importance. Within wide band gap material, zirconia owns a combination of physical and chemical properties that potentiate it as an excellent host for the aforementioned ions, envisaging its use in different areas, including in lighting and optical sensors applications, such as pressure sensors and biosensors. Following the demand for outstanding luminescent materials, there is also a request for fast, economic and an easy scale-up process for their production. Regarding these demands, laser floating zone, solution combustion synthesis and pulsed laser ablation in liquid techniques are explored in this thesis for the production of single crystals, nanopowders and nanoparticles of lanthanides doped zirconia based hosts. Simultaneously, a detailed study of the morphological, structural and optical properties of the produced materials is made. The luminescent characteristics of zirconia and yttria stabilized zirconia (YSZ) doped with different lanthanide ions (Ce3+ (4f1), Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8), Dy3+ (4f9), Er3+ (4f11), Tm3+ (4f12), Yb3+ (4f13)) and co-doped with Er3+,Yb3+ and Tm3+,Yb3+ are analysed. Besides the Stokes luminescence, the anti- Stokes emission upon infrared excitation (upconversion and black body radiation) is also analysed and discussed. The comparison of the luminescence characteristics in materials with different dimensions allowed to analyse the effect of size in the luminescent properties of the dopant lanthanide ions. The potentialities of application of the produced luminescent materials in solid state light, biosensors and pressure

Phenyl boron-based compounds as anion receptors for non-aqueous battery electrolytes

DOEpatents

Lee, Hung Sui; Yang, Xiao-Qing; McBreen, James; Sun, Xuehui

2002-01-01

Novel fluorinated boronate-based compounds which act as anion receptors in non-aqueous battery electrolytes are provided. When added to non-aqueous battery electrolytes, the fluorinated boronate-based compounds of the invention enhance ionic conductivity and cation transference number of non-aqueous electrolytes. The fluorinated boronate-based anion receptors include different fluorinated alkyl and aryl groups.

Water-based thixotropic polymer gel electrolyte for dye-sensitized solar cells.

PubMed

Park, Se Jeong; Yoo, Kichoen; Kim, Jae-Yup; Kim, Jin Young; Lee, Doh-Kwon; Kim, Bongsoo; Kim, Honggon; Kim, Jong Hak; Cho, Jinhan; Ko, Min Jae

2013-05-28

For the practical application of dye-sensitized solar cells (DSSCs), it is important to replace the conventional organic solvents based electrolyte with environmentally friendly and stable ones, due to the toxicity and leakage problems. Here we report a noble water-based thixotropic polymer gel electrolyte containing xanthan gum, which satisfies both the environmentally friendliness and stability against leakage and water intrusion. For application in DSSCs, it was possible to infiltrate the prepared electrolyte into the mesoporous TiO2 electrode at the fluidic state, resulting in sufficient penetration. As a result, this electrolyte exhibited similar conversion efficiency (4.78% at 100 mW cm(-2)) and an enhanced long-term stability compared to a water-based liquid electrolyte. The effects of water on the photovoltaic properties were examined elaborately from the cyclic voltammetry curves and impedance spectra. Despite the positive shift in the conduction band potential of the TiO2 electrode, the open-circuit voltage was enhanced by addition of water in the electrolyte due to the greater positive shift in the I(-)/I3(-) redox potential. However, due to the dye desorption and decreased diffusion coefficient caused by the water content, the short-circuit photocurrent density was reduced. These results will provide great insight into the development of efficient and stable water-based electrolytes.

A review of engineered zirconia surfaces in biomedical applications

PubMed Central

Yin, Ling; Nakanishi, Yoshitaka; Alao, Abdur-Rasheed; Song, Xiao-Fei; Abduo, Jaafar; Zhang, Yu

2017-01-01

Zirconia is widely used for load-bearing functional structures in medicine and dentistry. The quality of engineered zirconia surfaces determines not only the fracture and fatigue behaviour but also the low temperature degradation (ageing sensitivity), bacterial colonization and bonding strength of zirconia devices. This paper reviews the current manufacturing techniques for fabrication of zirconia surfaces in biomedical applications, particularly, in tooth and joint replacements, and influences of the zirconia surface quality on their functional behaviours. It discusses emerging manufacturing techniques and challenges for fabrication of zirconia surfaces in biomedical applications. PMID:29130030

Effect of sandblasting on surface roughness of zirconia-based ceramics and shear bond strength of veneering porcelain.

PubMed

He, Min; Zhang, Zutai; Zheng, Dongxiang; Ding, Ning; Liu, Yan

2014-01-01

This study aims to investigate the effect of sandblasting on the surface roughness of zirconia and the shear bond strength of the veneering porcelain. Pre-sintered zirconia plates were prepared and divided into four groups. Group A were not treated at all; group B were first sandblasted under 0.2 MPa pressure and then densely sintered; group C and D were sintered first, and then sandblasted under 0.2 MPa and 0.4 MPa pressures respectively. Surface roughness was measured and 3D roughness was reconstructed for the specimens, which were also analyzed with X-ray diffractometry. Finally after veneering porcelain sintering, shear bond tests were conducted. Sandblasting zirconia before sintering significantly increased surface roughness and the shear bond strength between zirconia and veneering porcelain (p<0.05). Sandblasting zirconia before sintering is a useful method to increase surface roughness and could successfully improve the bonding strength of veneering porcelain.

Reactions of yttria-stabilized zirconia with oxides and sulfates of various elements

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1978-01-01

The reactions between partially stabilized zirconia, containing 8 weight-percent yttria, and oxides and sulfates of various elements were studied at 1200, 1300, and 1400 C for times to 800, 400, and 200 hours, respectively. These oxides and sulfates represent impurities and additives potentially present in gas turbine fuels or impurities in the turbine combustion air as well as the elements of the substrate alloys in contact with zirconia. Based on the results, these compounds can be classified in four groups: (1) compounds which did not react with zirconia (Na2SO4, K2SO4, Cr2O3, Al2O3 and NiO); (2) compounds that reached completely with both zirconia phases (CaO, BaO, and BaSO4); (3) compounds that reacted preferentially with monoclinic zirconia (Na2O, K2O, CoO, Fe2O3, MgO, SiO2, and ZnO); and (4) compounds that reacted preferentially with cubic zirconia (V2O5, P2O5).

Evaluation of experimental coating to improve the zirconia-veneering ceramic bond strength.

PubMed

Matani, Jay D; Kheur, Mohit; Jambhekar, Shantanu Subhashchandra; Bhargava, Parag; Londhe, Aditya

2014-12-01

To evaluate the shear bond strength (SBS) between zirconia and veneering ceramic following different surface treatments of zirconia. The efficacy of an experimental zirconia coating to improve the bond strength was also evaluated. Zirconia strips were fabricated and were divided into four groups as per their surface treatment: polished (control), airborne-particle abrasion, laser irradiation, and application of the experimental coating. The surface roughness and the residual monoclinic content were evaluated before and after the respective surface treatments. A scanning electron microscope (SEM) analysis of the experimental surfaces was performed. All specimens were subjected to shear force in a universal testing machine. The SBS values were analyzed with one-way ANOVA followed by Bonferroni post hoc for groupwise comparisons. The fractured specimens were examined to observe the failure mode. The SBS (29.17 MPa) and roughness values (0.80) of the experimental coating group were the highest among the groups. The residual monoclinic content was minimal (0.32) when compared to the remaining test groups. SEM analysis revealed a homogenous surface well adhered to an undamaged zirconia base. The other test groups showed destruction of the zirconia surface. The analysis of failure following bond strength testing showed entirely cohesive failures in the veneering ceramic in all study groups. The experimental zirconia surface coating is a simple technique to increase the microroughness of the zirconia surface, and thereby improve the SBS to the veneering ceramic. It results in the least monoclinic content and produces no structural damage to the zirconia substructure. © 2014 by the American College of Prosthodontists.

Electrical, structural, thermal and electrochemical properties of corn starch-based biopolymer electrolytes.

PubMed

Liew, Chiam-Wen; Ramesh, S

2015-06-25

Biopolymer electrolytes containing corn starch, lithium hexafluorophosphate (LiPF6) and ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) are prepared by solution casting technique. Temperature dependence-ionic conductivity studies reveal Vogel-Tamman-Fulcher (VTF) relationship which is associated with free volume theory. Ionic liquid-based biopolymer electrolytes show lower glass transition temperature (Tg) than ionic liquid-free biopolymer electrolyte. X-ray diffraction (XRD) studies demonstrate higher amorphous region of ionic liquid-added biopolymer electrolytes. In addition, the potential stability window of the biopolymer electrolyte becomes wider and stable up to 2.9V. Conclusively, the fabricated electric double layer capacitor (EDLC) shows improved electrochemical performance upon addition of ionic liquid into the biopolymer electrolyte. The specific capacitance of EDLC based on ionic liquid-added polymer electrolyte is relatively higher than that of ionic liquid-free polymer electrolyte as depicted in cyclic voltammogram. Copyright © 2015 Elsevier Ltd. All rights reserved.

Osseointegration of zirconia implants: an SEM observation of the bone-implant interface.

PubMed

Depprich, Rita; Zipprich, Holger; Ommerborn, Michelle; Mahn, Eduardo; Lammers, Lydia; Handschel, Jörg; Naujoks, Christian; Wiesmann, Hans-Peter; Kübler, Norbert R; Meyer, Ulrich

2008-11-06

The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.

Effect of conductive additives to gel electrolytes on activated carbon-based supercapacitors

NASA Astrophysics Data System (ADS)

Barzegar, Farshad; Dangbegnon, Julien K.; Bello, Abdulhakeem; Momodu, Damilola Y.; Johnson, A. T. Charlie; Manyala, Ncholu

2015-09-01

This article is focused on polymer based gel electrolyte due to the fact that polymers are cheap and can be used to achieve extended potential window for improved energy density of the supercapacitor devices when compared to aqueous electrolytes. Electrochemical characterization of a symmetric supercapacitor devices based on activated carbon in different polyvinyl alcohol (PVA) based gel electrolytes was carried out. The device exhibited a maximum energy density of 24 Wh kg-1 when carbon black was added to the gel electrolyte as conductive additive. The good energy density was correlated with the improved conductivity of the electrolyte medium which is favorable for fast ion transport in this relatively viscous environment. Most importantly, the device remained stable with no capacitance lost after 10,000 cycles.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.

1988-01-01

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.

1988-09-13

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

Anion Solvation in Carbonate-Based Electrolytes

DOE PAGES

von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; ...

2015-11-16

The correlation between Li + solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. Now, most studies are dedicated to the solvation of Li +, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. Moreover, as a mirror effort to prior Li + solvation studies, this work focuses on the interactions between carbonate-based solvents andmore » two anions (hexafluorophosphate, PF 6–, and tetrafluoroborate, BF 4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.« less

Zinc-based electrolyte compositions, and related electrochemical processes and articles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kniajanski, Sergei; Soloveichik, Grigorii Lev

An aqueous electrolyte composition is described, including a zinc salt based on zinc acetate or zinc glocolate. The saturation concentration of zinc in the electrolyte composition is in the range of about 2.5M to about 3.5M. The composition also contains at least one salt of a monovalent cation. The molar ratio of zinc to the monovalent cation is about 1:2. An aqueous zinc electroplating bath, containing the aqueous electrolyte composition, is also disclosed, along with a method for the electrochemical deposition of zinc onto a substrate surface, using the electroplating bath. Related flow batteries are also described, including a catholyte,more » as well as an anolyte based on the aqueous electrolyte composition, with a membrane between the catholyte and the anolyte.« less

Zirconia in dental implantology: A review

PubMed Central

Apratim, Abhishek; Eachempati, Prashanti; Krishnappa Salian, Kiran Kumar; Singh, Vijendra; Chhabra, Saurabh; Shah, Sanket

2015-01-01

Background: Titanium has been the most popular material of choice for dental implantology over the past few decades. Its properties have been found to be most suitable for the success of implant treatment. But recently, zirconia is slowly emerging as one of the materials which might replace the gold standard of dental implant, i.e., titanium. Materials and Methods: Literature was searched to retrieve information about zirconia dental implant and studies were critically analyzed. PubMed database was searched for information about zirconia dental implant regarding mechanical properties, osseointegration, surface roughness, biocompatibility, and soft tissue health around it. The literature search was limited to English language articles published from 1975 to 2015. Results: A total of 45 papers met the inclusion criteria for this review, among the relevant search in the database. Conclusion: Literature search showed that some of the properties of zirconia seem to be suitable for making it an ideal dental implant, such as biocompatibility, osseointegration, favourable soft tissue response and aesthetics due to light transmission and its color. At the same time, some studies also point out its drawbacks. It was also found that most of the studies on zirconia dental implants are short-term studies and there is a need for more long-term clinical trials to prove that zirconia is worth enough to replace titanium as a biomaterial in dental implantology. PMID:26236672

Implant-supported fixed dental prostheses with CAD/CAM-fabricated porcelain crown and zirconia-based framework.

PubMed

Takaba, Masayuki; Tanaka, Shinpei; Ishiura, Yuichi; Baba, Kazuyoshi

2013-07-01

Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs. © 2012 by the American College of Prosthodontists.

Light transmittance of zirconia as a function of thickness and microhardness of resin cements under different thicknesses of zirconia

PubMed Central

Egilmez, Ferhan; Ergun, Gulfem; Kaya, Bekir M.

2013-01-01

Objective: The objective of this study was to compare microhardness of resin cements under different thicknesses of zirconia and the light transmittance of zirconia as a function of thickness. Study design: A total of 126 disc-shaped specimens (2 mm in height and 5 mm in diameter) were prepared from dual-cured resin cements (RelyX Unicem, Panavia F and Clearfil SA cement). Photoactivation was performed by using quartz tungsten halogen and light emitting diode light curing units under different thicknesses of zirconia. Then the specimens (n=7/per group) were stored in dry conditions in total dark at 37°C for 24 h. The Vicker’s hardness test was performed on the resin cement layer with a microhardness tester. Statistical significance was determined using multifactorial analysis of variance (ANOVA) (alpha=.05). Light transmittance of different thicknesses of zirconia (0.3, 0.5 and 0.8 mm) was measured using a hand-held radiometer (Demetron, Kerr). Data were analyzed using one-way ANOVA test (alpha=.05). Results: ANOVA revealed that resin cement and light curing unit had significant effects on microhardness (p < 0.001). Additionally, greater zirconia thickness resulted in lower transmittance. There was no correlation between the amount of light transmitted and microhardness of dual-cured resin cements (r = 0.073, p = 0.295). Conclusion: Although different zirconia thicknesses might result in insufficient light transmission, dual-cured resin cements under zirconia restorations could have adequate microhardness. Key words:Zirconia, microhardness, light transmittance, resin cement. PMID:23385497

Subsurface segregation of yttria in yttria stabilized zirconia

NASA Astrophysics Data System (ADS)

de Ridder, M.; van Welzenis, R. G.; van der Gon, A. W. Denier; Brongersma, H. H.; Wulff, S.; Chu, W.-F.; Weppner, W.

2002-09-01

The segregation behavior in 3 and 10 mol % polycrystalline yttria stabilized zirconia (YSZ), calcined at temperatures ranging from 300 to 1600 degC, is characterized using low-energy ion scattering (LEIS). In order to be able to separate the Y and Zr LEIS signals, YSZ samples have been prepared using isotopically enriched 94ZrO2 instead of natural zirconia. The samples are made via a special precipitation method at a low temperature. The segregation to the outermost surface layer is dominated by impurities. The increased impurity levels are restricted to this first layer, which underlines the importance of the use of LEIS for this study. For temperatures of 1000 degC and higher, the oxides of the impurities Na, Si, and Ca even cover the surface completely. The performance of a device like the solid oxide fuel cell which has an YSZ electrolyte and a working temperature around 1000 degC, will, therefore, be strongly hampered by these impurities. The reduction of impurities, to prevent accumulation at the surface, will only be effective if the total impurity bulk concentration can be reduced below the 10 ppm level. Due to the presence of the impurities, yttria cannot accumulate in the outermost layer. It does so, in contrast to the general belief, in the subsurface layer and to much higher concentrations than the values reported previously. The difference in the interfacial free energies of Y2O3 and ZrO2 is determined to be -21plus-or-minus3 kJ/mol.

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

NASA Astrophysics Data System (ADS)

Aliahmad, Nojan; Shrestha, Sudhir; Varahramyan, Kody; Agarwal, Mangilal

2016-06-01

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10-3 S cm-1. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providing flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g-1 for standard metallic current collectors and (ii) 99.5 mAh g-1 for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed.

Towards long lasting zirconia-based composites for dental implants. Part I: innovative synthesis, microstructural characterization and in vitro stability.

PubMed

Palmero, Paola; Fornabaio, Marta; Montanaro, Laura; Reveron, Helen; Esnouf, Claude; Chevalier, Jérôme

2015-05-01

In order to fulfill the clinical requirements for strong, tough and stable ceramics used in dental applications, we designed and developed innovative zirconia-based composites, in which equiaxial α-Al2O3 and elongated SrAl12O19 phases are dispersed in a ceria-stabilized zirconia matrix. The composite powders were prepared by an innovative surface coating route, in which commercial zirconia powders were coated by inorganic precursors of the second phases, which crystallize on the zirconia particles surface under proper thermal treatment. Samples containing four different ceria contents (in the range 10.0-11.5 mol%) were prepared by carefully tailoring the amount of the cerium precursor during the elaboration process. Slip cast green bodies were sintered at 1450 °C for 1 h, leading to fully dense materials. Characterization of composites by SEM and TEM analyses showed highly homogeneous microstructures with an even distribution of both equiaxial and elongated-shape grains inside a very fine zirconia matrix. Ce content plays a major role on aging kinetics, and should be carefully controlled: sample with 10 mol% of ceria were transformable, whereas above 10.5 mol% there is negligible or no transformation during autoclave treatment. Thus, in this paper we show the potential of the innovative surface coating route, which allows a perfect tailoring of the microstructural, morphological and compositional features of the composites; moreover, its processing costs and environmental impacts are limited, which is beneficial for further scale-up and real use in the biomedical field. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of an internal coating technique on tensile bond strengths of resin cements to zirconia ceramics.

PubMed

Kitayama, Shuzo; Nikaido, Toru; Maruoka, Rena; Zhu, Lei; Ikeda, Masaomi; Watanabe, Akihiko; Foxton, Richard M; Miura, Hiroyuki; Tagami, Junji

2009-07-01

This study was conducted to enhance the tensile bond strengths of resin cements to zirconia ceramics. Fifty-six zirconia ceramic specimens (Cercon Base) and twenty-eight silica-based ceramic specimens (GN-1, GN-1 Ceramic Block) were air-abraded using alumina. Thereafter, the zirconia ceramic specimens were divided into two subgroups of 28 each according to the surface pretreatment; no pretreatment (Zr); and the internal coating technique (INT). For INT, the surface of zirconia was coated by fusing silica-based ceramics (Cercon Ceram Kiss). Ceramic surfaces were conditioned with/without a silane coupling agent followed by bonding with one of two resin cements; Panavia F 2.0 (PF) and Superbond C&B (SB). After 24 hours storage in water, the tensile bond strengths were tested (n=7). For both PF and SB, silanization significantly improved the bond strength to GN-1 and INT (p<0.05). The INT coating followed by silanizaton demonstrated enhancement of bonding to zirconia ceramics.

Synthesis and characterization of thermally stable zirconia based mesoporous nanosilica with metalloporphyrin encapsulation

NASA Astrophysics Data System (ADS)

Nadeem, Saad; Iqbal, Farukh; Mutalib, Mohamed Ibrahim Abdul; Abdullah, Bawadi; Shaharun, Maizatul Shima

2017-10-01

Metal composite materials-48 (MCM-48) with silica zirconia mesoporous matrix (having a Zr/Si ratio of 0.02) has been developed successfully using autogenous conditions and Copper tetra phenyl porphyrin (CuTPP) inclusion via flexible ligand approach. Thermo gravimetric analysis (TGA) was used to study the thermal stability which gives the stability up to 700°C, Fourier transform infrared spectroscopy (FTIR) for the functional group attachment also confirmed the MCM-48 structure and the Zirconia addition and X-Ray photon spectroscopy (XPS) for the binding energies and bonding also revealed the surface Zr4+ states. DRS-UV-Vis study for the photophysical behaviour, visible light activation and band gap reduction which reduced from 5.6 to 2.8 eV. All the characterizations have confirmed that nanoscale mesoporous silica with successful inclusion of zirconia in the matrix and the encapsulation of CuTPP was confirmed via diffuse reflectance (DR Uv-Vis) spectroscopy.

Magnesium-based energy storage systems and methods having improved electrolytes

DOEpatents

Liu, Tianbiao; Li, Guosheng; Liu, Jun; Shao, Yuyan

2016-12-20

Electrolytes for Mg-based energy storage devices can be formed from non-nucleophilic Mg.sup.2+ sources to provide outstanding electrochemical performance and improved electrophilic susceptibility compared to electrolytes employing nucleophilic sources. The instant electrolytes are characterized by high oxidation stability (up to 3.4 V vs Mg), improved electrophile compatibility and electrochemical reversibility (up to 100% coulombic efficiency). Synthesis of the Mg.sup.2+ electrolytes utilizes inexpensive and safe magnesium dihalides as non-nucleophilic Mg.sup.2+ sources in combination with Lewis acids, MR.sub.aX.sub.3-a (for 3.gtoreq.a.gtoreq.1). Furthermore, addition of free-halide-anion donors can improve the coulombic efficiency of Mg electrolytes from nucleophilic or non-nucleophilic Mg.sup.2+ sources.

Shear bond strength of veneering porcelain to zirconia: Effect of surface treatment by CNC-milling and composite layer deposition on zirconia.

PubMed

Santos, R L P; Silva, F S; Nascimento, R M; Souza, J C M; Motta, F V; Carvalho, O; Henriques, B

2016-07-01

The purpose of this study was to evaluate the shear bond strength of veneering feldspathic porcelain to zirconia substrates modified by CNC-milling process or by coating zirconia with a composite interlayer. Four types of zirconia-porcelain interface configurations were tested: RZ - porcelain bonded to rough zirconia substrate (n=16); PZ - porcelain bonded to zirconia substrate with surface holes (n=16); RZI - application of a composite interlayer between the veneering porcelain and the rough zirconia substrate (n=16); PZI - application of a composite interlayer between the porcelain and the zirconia substrate treated by CNC-milling (n=16). The composite interlayer was composed of zirconia particles reinforced porcelain (30%, vol%). The mechanical properties of the ceramic composite have been determined. The shear bond strength test was performed at 0.5mm/min using a universal testing machine. The interfaces of fractured and untested specimens were examined by FEG-SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The one-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results (α=0.05). The shear bond strength of PZ (100±15MPa) and RZI (96±11MPa) specimens were higher than that recorded for RZ (control group) specimens (89±15MPa), although not significantly (p>0.05). The highest shear bond strength values were recorded for PZI specimens (138±19MPa), yielding a significant improvement of 55% relative to RZ specimens (p<0.05). This study shows that it is possible to highly enhance the zirconia-porcelain bond strength - even by ~55% - by combining surface holes in zirconia frameworks and the application of a proper ceramic composite interlayer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliahmad, Nojan; Shrestha, Sudhir; Varahramyan, Kody

2016-06-15

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10{sup −3} S cm{sup −1}. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providingmore » flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g{sup −1} for standard metallic current collectors and (ii) 99.5 mAh g{sup −1} for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed.« less

Novel fabrication method for zirconia restorations: bonding strength of machinable ceramic to zirconia with resin cements.

PubMed

Kuriyama, Soichi; Terui, Yuichi; Higuchi, Daisuke; Goto, Daisuke; Hotta, Yasuhiro; Manabe, Atsufumi; Miyazaki, Takashi

2011-01-01

A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramic bonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed in this study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconia plate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconia specimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) were carried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89 MPa). SCT revealed that the bonding strengths of test groups using resin cement were significantly higher than those of Control. Notably, the bonding strengths of RE and ML were above 25 MPa even after 10,000 times of thermal cycling -adequately meeting the ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in that a CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement.

Bonding of Resin Cement to Zirconia with High Pressure Primer Coating

PubMed Central

Wang, Ying-jie; Jiao, Kai; Liu, Yan; Zhou, Wei; Shen, Li-juan; Fang, Ming; Li, Meng; Zhang, Xiang; Tay, Franklin R.; Chen, Ji-hua

2014-01-01

Objectives To investigate the effect of air-drying pressure during ceramic primer coating on zirconia/resin bonding and the surface characteristics of the primed zirconia. Methods Two ceramic primers (Clearfil Ceramic Primer, CCP, Kuraray Medical Inc. and Z-Prime Plus, ZPP, Bisco Inc.) were applied on the surface of air-abraded zirconia (Katana zirconia, Noritake) and dried at 4 different air pressures (0.1–0.4 MPa). The primed zirconia ceramic specimens were bonded with a resin-based luting agent (SA Luting Cement, Kuraray). Micro-shear bond strengths of the bonded specimens were tested after 3 days of water storage or 5,000× thermocycling (n = 12). Failure modes of the fractured specimens were examined with scanning electron miscopy. The effects of air pressure on the thickness of the primer layers and the surface roughness (Sa) of primed zirconia were evaluated using spectroscopic ellipsometry (n = 6), optical profilometry and environmental scanning electron microscopy (ESEM) (n = 6), respectively. Results Clearfil Ceramic Primer air-dried at 0.3 and 0.4 MPa, yielding significantly higher µSBS than gentle air-drying subgroups (p<0.05). Compared to vigorous drying conditions, Z-Prime Plus air-dried at 0.2 MPa exhibited significantly higher µSBS (p<0.05). Increasing air-drying pressure reduced the film thickness for both primers. Profilometry measurements and ESEM showed rougher surfaces in the high pressure subgroups of CCP and intermediate pressure subgroup of ZPP. Conclusion Air-drying pressure influences resin/zirconia bond strength and durability significantly. Higher air-drying pressure (0.3-0.4 MPa) for CCP and intermediate pressure (0.2 MPa) for ZPP are recommended to produce strong, durable bonds between resin cement and zirconia ceramics. PMID:24992678

Ion Pairing and Diffusion in Magnesium Electrolytes Based on Magnesium Borohydride.

PubMed

Samuel, Devon; Steinhauser, Carl; Smith, Jeffrey G; Kaufman, Aaron; Radin, Maxwell D; Naruse, Junichi; Hiramatsu, Hidehiko; Siegel, Donald J

2017-12-20

One obstacle to realizing a practical, rechargeable magnesium-ion battery is the development of efficient Mg electrolytes. Electrolytes based on simple Mg(BH 4 ) 2 salts suffer from poor salt solubility and/or low conductivity, presumably due to strong ion pairing. Understanding the molecular-scale processes occurring in these electrolytes would aid in overcoming these performance limitations. Toward this goal, the present study examines the solvation, agglomeration, and transport properties of a family of Mg electrolytes based on the Mg(BH 4 ) 2 salt using classical molecular dynamics. These properties were examined across five different solvents (tetrahydrofuran and the glymes G1-G4) and at four salt concentrations ranging from the dilute limit up to 0.4 M. Significant and irreversible salt agglomeration was observed in all solvents at all nondilute Mg(BH 4 ) 2 concentrations. The degree of clustering observed in these divalent Mg systems is much larger than that reported for electrolytes containing monovalent cations, such as Li. The salt agglomeration rate and diffusivity of Mg 2+ were both observed to correlate with solvent self-diffusivity: electrolytes using longer- (shorter-) chain solvents had the lowest (highest) Mg 2+ diffusivity and agglomeration rates. Incorporation of Mg 2+ into Mg 2+ -BH 4 - clusters significantly reduces the diffusivity of Mg 2+ by restricting displacements to localized motion within largely immobile agglomerates. Consequently, diffusion is increasingly impeded with increasing Mg(BH 4 ) 2 concentration. These data are consistent with the solubility limitations observed experimentally for Mg(BH 4 ) 2 -based electrolytes and highlight the need for strategies that minimize salt agglomeration in electrolytes containing divalent cations.

Long-Term Effects on Graphene Supercapacitors of Using a Zirconia Bowl and Zirconia Balls for Ball-Mill mixing of Active Materials

NASA Astrophysics Data System (ADS)

Song, Dae-Hoon; Kim, Jin-Young; Kahng, Yung Ho; Cho, Hoonsung; Kim, Eung-Sam

2018-04-01

Improving the energy storage performance of supercapacitor electrodes based on reduced graphene oxide (RGO) is one of the main subjects in this research field. However, when a zirconia bowl and zirconia balls were used for ball-mill mixing of the active materials for RGO supercapacitors, the energy storage performance deteriorated over time. Our study revealed that the source of the problem was the inclusion of zirconia bits from abrasion of the bowl and the balls during the ballmill mixing, which increased during a period of 1 year. We probed two solutions to this problem: 1) hydrofluoric (HF) acid treatment of the RGO supercapacitors and 2) use of a tempered steel bowl and tempered steel balls for the mixing. For both cases, the energy storage performance was restored to near the initial level, showing a specific capacitance ( C sp ) of 200 F/g. Our results should lead to progress in research on RGO supercapacitors.

Bioactivity and biocompatibility of hydroxyapatite-based bioceramic coatings on zirconium by plasma electrolytic oxidation.

PubMed

Aktuğ, Salim Levent; Durdu, Salih; Yalçın, Emine; Çavuşoğlu, Kültigin; Usta, Metin

2017-02-01

In the present work, hydroxyapatite (HAP)-based plasma electrolytic oxide (PEO) coatings were produced on zirconium at different current densities in a solution containing calcium acetate and β-calcium glycerophosphate by a single step. The phase structure, surface morphology, functional groups, thickness and roughness of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), eddy current method and surface profilometer, respectively. The phases of cubic-zirconia, calcium zirconate and HAP were detected by XRD. The amount of HAP and calcium zirconate increased with increasing current density. The surface of the coatings was very porous and rough. Moreover, bioactivity and biocompatibility of the coatings were analyzed in vitro immersion simulated body fluid (SBF) and MTT (3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyl tetrazolium bromide) assay, hemolysis assay and bacterial formation. The apatite-forming ability of the coatings was evaluated after immersion in SBF up to 28days. After immersion, the bioactivity of HAP-based coatings on zirconium was greater than the ones of uncoated zirconium and zirconium oxide-based surface. The bioactivity of PEO surface on zirconium was significantly improved under SBF conditions. The bacterial adhesion of the coatings decreased with increasing current density. The bacterial adhesion of the coating produced at 0.370A/cm 2 was minimum compared to uncoated zirconium coated at 0.260 and 0.292A/cm 2 . The hemocompatibility of HAP-based surfaces was improved by PEO. The cell attachment and proliferation of the PEO coatings were better than the one of uncoated zirconium according to MTT assay results. Copyright © 2016 Elsevier B.V. All rights reserved.

[Influence on mechanical properties and microstructure of nano-zirconia toughened alumina ceramics with nano-zirconia content].

PubMed

Wang, Guang-Kui; Kang, Hong; Bao, Guang-Jie; Lv, Jin-Jun; Gao, Fei

2006-10-01

To investigate the mechanical properties and microstructure of nano -zirconia toughened alumina ceramics with variety of nano-zirconia content in centrifugal infiltrate casting processing of dental all-ceramic. Composite powder with different ethanol-water ratio, obtained serosity from ball milling and centrifugal infiltrate cast processing of green, then sintered at 1 450 degrees C for 8 h. The physical and mechanical properties of the sintered sample after milling and polishing were tested. Microstructures of the surface and fracture of the sintered sample were investigated by SEM. The experimental results showed that there had statistical significience (P < 0.01) on static three-point flexure strength and Vickers Hardness in three kinds of different nano-zirconia content sintered sample. Fracture toughness of 20% group was different from other two groups, while 10% group had not difference from 30% group (P < 0.05). The mechanical properties of this ceramic with 20% nano-zirconia was the best of the three, the static three-point flexure strength was (433 +/- 19) MPa and fracture toughness was (7.50 +/- 0.56) MPa x min 1/2. The intra/inter structure, fracture of intragranular and intergranular on the surface and fracture of sintered sample in microstrucre was also found. Intra/inter structure has strengthen toughness in ceramics. It has better toughness with 20% nano-zirconia, is suitable dental all-ceramic restoratives.

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, John J.

1995-01-01

Compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Novel Non-Carbonate Based Electrolytes for Silicon Anodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Ye; Yang, Johnny; Cheng, Gang

2016-09-09

Substantial improvement in the energy density of rechargeable lithium batteries is required to meet the future needs for electric and plug-in electric vehicles (EV and PHEV). Present day lithium ion battery technology is based on shuttling lithium between graphitic carbon and inorganic oxides. Non-graphitic anodes, such as silicon can provide significant improvements in energy density but are currently limited in cycle life due to reactivity with the electrolyte. Wildcat/3M proposes the development of non-carbonate electrolyte formulations tailored for silicon alloy anodes. Combining these electrolytes with 3M’s anode and an NMC cathode will enable up to a 20% increase in themore » volumetric cell energy density, while still meeting the PHEV/EV cell level cycle/calendar life goals.« less

Ether-based nonflammable electrolyte for room temperature sodium battery

NASA Astrophysics Data System (ADS)

Feng, Jinkui; Zhang, Zhen; Li, Lifei; Yang, Jian; Xiong, Shenglin; Qian, Yitai

2015-06-01

Safety problem is one of the key points that hinder the development of room temperature sodium batteries. In this paper, four well-known nonflammable organic compounds, Trimethyl Phosphate (TMP), Tri(2,2,2-trifluoroethyl) phosphite (TFEP), Dimethyl Methylphosphonate (DMMP), Methyl nonafluorobuyl Ether (MFE), are investigated as nonflammable solvents in sodium batteries for the first time. Among them, MFE is stable towards sodium metal at room temperature. The electrochemical properties and electrode compatibility of MFE based electrolyte are investigated. Both Prussian blue cathode and carbon nanotube anode show good electrochemical performance retention in this electrolyte. The results suggest that MFE is a promising option as nonflammable electrolyte additive for sodium batteries.

Energetics of zirconia stabilized by cation and nitrogen substitution

NASA Astrophysics Data System (ADS)

Molodetsky, Irina

Tetragonal and cubic zirconia are used in advanced structural ceramics, fuel cells, oxygen sensors, nuclear waste ceramics and many other applications. These zirconia phases are stabilized at room temperature (relative to monoclinic phase for pure zirconia) by cation and nitrogen substitution. This work is aimed at a better understanding of the mechanisms of stabilization of the high-temperature zirconia. phases. Experimental data are produced on the energetics of zirconia stabilized by yttria and calcia, energetics of nitrogen-oxygen substitution in zirconia and cation doped zirconia, and energetics of x-ray amorphous zirconia. obtained by low-temperature synthesis. High-temperature oxide melt solution enables direct measurement of enthalpies of formation of these refractory oxides. The enthalpy of the monoclinic to cubic phase transition of zirconia is DeltaHm-c = 12.2 +/- 1.2 kJ/mol. For cubic phases of YSZ at low yttria contents, a straight line DeltaH f,YSZ = -(52.4 +/- 3.6)x + (12.2 +/- 1.2) approximates the enthalpy of formation as a function of the yttria content, x (0. 1 < x < 0.3). Use of the quadratic fit DeltaHf,YSZ = 126.36 x 2 - 81.29 x + 12.37 (0.1 ≲ x ≲ 0.53) indicates that yttria stabilizes the cubic phase in enthalpy at low dopant content and destabilizes the cubic phase as yttria content increases. Positive entropy of mixing in YSZ and small enthalpy of long range ordering in 0.47ZrO2-0.53YO1.5, DeltaHord = -2.4 +/- 3.0 kJ/mol, indicate presence of short range ordering in YSZ. The enthalpy of formation of calcia stabilized zirconia as a function of calcia content x, is approximated as DeltaHf,c = (-91.4 +/- 3.8) x + (13.5 +/- 1.7) kJ/mol. The enthalpy of oxygen-nitrogen substitution, DeltaHO-N, in zirconium oxynitrides is a linear function of nitrogen content. DeltaH O-N ˜ -500 kJ/mol N is for Ca (Y)-Zr-N-O and Zr-N-O oxynitrides and DeltaHO-N ˜ -950 kJ/mol N is for Mg-Zr-N-O oxynitrides. X-ray amorphous zirconia is 58.6 +/- 3.3 kJ/mol less

Study and development of sulfated zirconia based proton exchange fuel cell membranes

NASA Astrophysics Data System (ADS)

Kemp, Brittany Wilson

With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with NafionRTM, the main membrane for PEMFCs, has not been solved. NafionRTM restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to NafionRTM in PEMFCs. The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. The fabricated membranes showed a proton conductivity of 0.016 S/cm in comparison to the proton conductivity of Nafion RTM (0.05 S/cm). Both formic acid and methanol had a lower crossover flux through the sulfated zirconia membranes (formic acid- 2.89x10 -7 mols/cm2s and methanol-1.78x10-9 mols/cm2s) than through NafionRTM (formic acid-2.03x10 -8 mols/cm2s methanol-2.42x10-6 mols/cm 2s), indicating that a sulfated zirconia PEMFC may serve as a replacement for NafionRTM.

[Effects of colorants on yttria stabilized tetragonal zirconia polycrystals powder].

PubMed

Wang, Bo; Chen, Jianfeng; Zhang, Yanchun; Wang, Ru

2015-10-01

To evaluate the effect of Fe2O3 and CeO2 as colorants on yttria stabilized tetragonal zirconia poly-crystals (Y-TZP) powder. The spray granulation slurry of colored zirconia was prepared with different concentrations of Fe2O3 (0.15%) and CeO2 (4%), which were added in Y-TZP. Zirconia powder was made by spray granulation. The powder specimens were divided into three groups: uncolored zirconia, Fe2O3 (0.15%) zirconia, and CeO2 (4%) zirconia. The particle morphologies of the powder specimens were measured with a laser particle size analyzer and an optical microscope. The differences in D50 among the three groups were statistically significant (P<0.05). Group Fe2O3 showed a significant difference from groups CeO2 and uncolored zirconia (P<0.05). Group uncolored zirconia showed no significant difference from group CeO2 (P>0.05). Mostly spherical powder was observed in the three groups. Fe2O3 as a colorant can affect particles, whereas CeO2 has no effect.

Synthesis and characterization of nanocrystalline mesoporous zirconia using supercritical drying.

PubMed

Tyagi, Beena; Sidhpuria, Kalpesh; Shaik, Basha; Jasra, Raksh Vir

2006-06-01

Synthesis of nano-crystalline zirconia aerogel was done by sol-gel technique and supercritical drying using n-propanol solvent at and above supercritical temperature (235-280 degrees C) and pressure (48-52 bar) of n-propanol. Zirconia xerogel samples have also been prepared by conventional thermal drying method to compare with the super critically dried samples. Crystalline phase, crystallite size, surface area, pore volume, and pore size distribution were determined for all the samples in detail to understand the effect of gel drying methods on these properties. Supercritical drying of zirconia gel was observed to give thermally stable, nano-crystalline, tetragonal zirconia aerogels having high specific surface area and porosity with narrow and uniform pore size distribution as compared to thermally dried zirconia. With supercritical drying, zirconia samples show the formation of only mesopores whereas in thermally dried samples, substantial amount of micropores are observed along with mesopores. The samples prepared using supercritical drying yield nano-crystalline zirconia with smaller crystallite size (4-6 nm) as compared to higher crystallite size (13-20 nm) observed with thermally dried zirconia.

Resin adhesion strengths to zirconia ceramics after primer treatment with silane coupling monomer or oligomer.

PubMed

Okada, Masahiro; Inoue, Kazusa; Irie, Masao; Taketa, Hiroaki; Torii, Yasuhiro; Matsumoto, Takuya

2017-09-26

Resin bonding to zirconia ceramics is difficult to achieve using the standard methods for conventional silica-based dental ceramics, which employ silane coupling monomers as primers. The hypothesis in this study was that a silane coupling oligomer -a condensed product of silane coupling monomers- would be a more suitable primer for zirconia. To prove this hypothesis, the shear bond strengths between a composite resin and zirconia were compared after applying either a silane coupling monomer or oligomer. The shear bond strength increased after applying a non-activated ethanol solution of the silane coupling oligomer compared with that achieved when applying the monomer. Thermal treatment of the zirconia at 110°C after application of the silane coupling agents was essential to improve the shear bond strength between the composite resin cement and zirconia.

A GdAlO3 Perovskite Oxide Electrolyte-Based NOx Solid-State Sensor.

PubMed

Xiao, Yihong; Wang, Dongmei; Cai, Guohui; Zheng, Yong; Zhong, Fulan

2016-11-25

NO x is a notorious emission from motor vehicles and chemical factories as the precursor of acid rain and photochemical smog. Although zirconia-based NO x sensors have been developed and showed high sensitivity and selectivity at a high temperature of above 800 °C, they fail to show good performance, and even don't work at the typical work temperature window of the automotive engine (<500 °C). It still is a formidable challenge for development of mild-temperature NO x detector or sensor. Herein, a novel amperometric solid-state NO x sensor was developed using perovskite-type oxide Gd 1-x Ca x AlO 3-δ (GCA) as the electrolyte and NiO as the sensing electrode. NO x sensing properties of the device were investigated at the temperature region of 400-500 °C. The response current value at -300 mV was almost linearly proportional to the NO x concentration between 300 and 500 ppm at 500 °C. At such a temperature, the optimal sensor gave the highest NO 2 sensitivity of 20.15 nA/ppm, and the maximum response current value reached 5.57 μA. Furthermore, a 90% response and 90% recover time to 500 ppm NO 2 were about 119 and 92 s, respectively. The excellent selectivity and stability towards NO x sensing showed the potential application of the sensor in motor vehicles.

A GdAlO3 Perovskite Oxide Electrolyte-Based NOx Solid-State Sensor

NASA Astrophysics Data System (ADS)

Xiao, Yihong; Wang, Dongmei; Cai, Guohui; Zheng, Yong; Zhong, Fulan

2016-11-01

NOx is a notorious emission from motor vehicles and chemical factories as the precursor of acid rain and photochemical smog. Although zirconia-based NOx sensors have been developed and showed high sensitivity and selectivity at a high temperature of above 800 °C, they fail to show good performance, and even don’t work at the typical work temperature window of the automotive engine (<500 °C). It still is a formidable challenge for development of mild-temperature NOx detector or sensor. Herein, a novel amperometric solid-state NOx sensor was developed using perovskite-type oxide Gd1-xCaxAlO3-δ(GCA) as the electrolyte and NiO as the sensing electrode. NOx sensing properties of the device were investigated at the temperature region of 400-500 °C. The response current value at -300 mV was almost linearly proportional to the NOx concentration between 300 and 500 ppm at 500 °C. At such a temperature, the optimal sensor gave the highest NO2 sensitivity of 20.15 nA/ppm, and the maximum response current value reached 5.57 μA. Furthermore, a 90% response and 90% recover time to 500 ppm NO2 were about 119 and 92 s, respectively. The excellent selectivity and stability towards NOx sensing showed the potential application of the sensor in motor vehicles.

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, J.J.

1995-01-17

Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Stable dye-sensitized solar cells based on a gel electrolyte with ethyl cellulose as the gelator

NASA Astrophysics Data System (ADS)

Vasei, Maryam; Tajabadi, Fariba; Jabbari, Ali; Taghavinia, Nima

2015-09-01

A simple gelating process is developed for the conventional acetonitrile-based electrolyte of dye solar cells, based on ethyl cellulose as the gelator. The electrolyte becomes quasi-solid-state upon addition of an ethanolic solution of ethyl cellulose to the conventional acetonitrile-based liquid electrolyte. The photovoltaic conversion efficiency with the new gel electrolyte is only slightly lower than with the liquid electrolyte, e.g., 6.5 % for liquid electrolyte versus 5.9 % for gel electrolyte with 5.8 wt% added ethyl cellulose. Electrolyte gelation has small effect on the ionic diffusion coefficient of iodide, and the devices are remarkably stable for at least 550 h under irradiation at 55 °C.

High-efficiency dye-sensitized solar cells with ferrocene-based electrolytes.

PubMed

Daeneke, Torben; Kwon, Tae-Hyuk; Holmes, Andrew B; Duffy, Noel W; Bach, Udo; Spiccia, Leone

2011-03-01

Dye-sensitized solar cells based on iodide/triiodide (I(-)/I(3)(-)) electrolytes are viable low-cost alternatives to conventional silicon solar cells. However, as well as providing record efficiencies of up to 12.0%, the use of I(-)/I(3)(-) in such solar cells also brings about certain limitations that stem from its corrosive nature and complex two-electron redox chemistry. Alternative redox mediators have been investigated, but these generally fall well short of matching the performance of conventional I(-)/I(3)(-) electrolytes. Here, we report energy conversion efficiencies of 7.5% (simulated sunlight, AM1.5, 1,000 W m(-2)) for dye-sensitized solar cells combining the archetypal ferrocene/ferrocenium (Fc/Fc(+)) single-electron redox couple with a novel metal-free organic donor-acceptor sensitizer (Carbz-PAHTDTT). These Fc/Fc(+)-based devices exceed the efficiency achieved for devices prepared using I(-)/I(3)(-) electrolytes under comparable conditions, revealing the great potential of ferrocene-based electrolytes in future dye-sensitized solar cells applications. This improvement results from a more favourable matching of the redox potential of the ferrocene couple with that of the new donor-acceptor sensitizer.

Internal Nano Voids in Yttria-Stabilised Zirconia (YSZ) Powder

PubMed Central

Barad, Chen; Shekel, Gal; Shandalov, Michael; Hayun, Hagay; Kimmel, Giora; Shamir, Dror; Gelbstein, Yaniv

2017-01-01

Porous yttria-stabilised zirconia ceramics have been gaining popularity throughout the years in various fields, such as energy, environment, medicine, etc. Although yttria-stabilised zirconia is a well-studied material, voided yttria-stabilised zirconia powder particles have not been demonstrated yet, and might play an important role in future technology developments. A sol-gel synthesis accompanied by a freeze-drying process is currently being proposed as a method of obtaining sponge-like nano morphology of embedded faceted voids inside yttria-stabilised zirconia particles. The results rely on a freeze-drying stage as an effective and simple method for generating nano-voided yttria-stabilised zirconia particles without the use of template-assisted additives. PMID:29258227

Internal Nano Voids in Yttria-Stabilised Zirconia (YSZ) Powder.

PubMed

Barad, Chen; Shekel, Gal; Shandalov, Michael; Hayun, Hagay; Kimmel, Giora; Shamir, Dror; Gelbstein, Yaniv

2017-12-18

Porous yttria-stabilised zirconia ceramics have been gaining popularity throughout the years in various fields, such as energy, environment, medicine, etc. Although yttria-stabilised zirconia is a well-studied material, voided yttria-stabilised zirconia powder particles have not been demonstrated yet, and might play an important role in future technology developments. A sol-gel synthesis accompanied by a freeze-drying process is currently being proposed as a method of obtaining sponge-like nano morphology of embedded faceted voids inside yttria-stabilised zirconia particles. The results rely on a freeze-drying stage as an effective and simple method for generating nano-voided yttria-stabilised zirconia particles without the use of template-assisted additives.

[Microwave sintering of nanometer powder of alumina and zirconia-based dental ceramics].

PubMed

Chen, Yi-Fan; Lu, Dong-Mei; Wan, Qian-Bing; Jin, Yong; Zhu, Ju-Mu

2006-02-01

The objective of the present study was to investigate the feasibility and reliability of sintering alumina and zirconia-based all-ceramic materials through a recently introduced microwave heating technique. The variation of crystal phases, the growth of grain sizes and microstructural features of these materials were evaluated after sintering. Four different groups of powder (l00%Al2O3, 60%Al2O3+40%ZrO2, 40% Al2O3+60%ZrO2, 100% ZrO2) were respectively press-compacted to fabricate green disk samples, 5 specimen of each group were prepared. All the samples were surrounded by refractory materials for heat containment and processed at 1 600 degrees C in a domestic microwave oven (850 W, 2 450 MHz), 1 600 degrees C/5 min for heating rate, 10 min for holding time. After sintering, the phase composition and average grain size of these ceramics were examined using X-ray diffraction (XRD). Their microstructure characteristics were studied by scanning electron microscopy (SEM). All the specimens were successfully sintered with the application of microwave heating system in combination with a suitable thermal insulator. No phase change was found in alumina while monoclinic-zirconia was found to be transformed to tetragonal-zirconia. A little grain size growth of Al2O3 and ZrO2 has been observed with Al2O3 24.1 nm/before and 51.8 nm/after; ZrO2 25.3 nm/before and 29.7 nm/after. The SEM photos indicated that the microwave-sintered Al2O3-ZrO2 ceramics had a uniform crystal distribution and their crystal sizes could be maintained within the range of nanometers. It is expected that in the near future microwave heating system could be a promising substitute for conventional processing methods due to its unparalled advantages, including more rapid heating rate, shortened sintering time, superfine grain size, improved microstructure and much less expensive equipment.

Homogeneous lithium electrodeposition with pyrrolidinium-based ionic liquid electrolytes.

PubMed

Grande, Lorenzo; von Zamory, Jan; Koch, Stephan L; Kalhoff, Julian; Paillard, Elie; Passerini, Stefano

2015-03-18

In this study, we report on the electroplating and stripping of lithium in two ionic liquid (IL) based electrolytes, namely N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyr14FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), and mixtures thereof, both on nickel and lithium electrodes. An improved method to evaluate the Li cycling efficiency confirmed that homogeneous electroplating (and stripping) of Li is possible with TFSI-based ILs. Moreover, the presence of native surface features on lithium, directly observable via scanning electron microscope imaging, was used to demonstrate the enhanced electrolyte interphase (SEI)-forming ability, that is, fast cathodic reactivity of this class of electrolytes and the suppressed dendrite growth. Finally, the induced inhomogeneous deposition enabled us to witness the SEI cracking and revealed previously unreported bundled Li fibers below the pre-existing SEI and nonrod-shaped protuberances resulting from Li extrusion.

Electrolyte and acid-base abnormalities associated with purging behaviors.

PubMed

Mehler, Philip S; Walsh, Kristine

2016-03-01

Eating disorders that are associated with purging behaviors are complicated by frequent blood electrolyte and acid-base abnormalities. Herein, we review the major electrolyte and acid-base abnormalities and their treatment methods. The body of rigorous, eating disorder-specific literature on this topical area is not robust enough to perform a systematic review as defined by PRISMA guidelines. Therefore, a qualitative review of mostly medical literature was conducted. Hypokalemia, hyponatremia, and sodium chloride-responsive metabolic alkalosis are the most common serum changes that occur as a result of purging behaviors. They vary depending on the mode and frequency of purging behaviors. They can all potentially cause dangerous medical complications and are in need of definitive medical treatment. Eating disorders that are associated with purging behaviors are associated with a number of electrolyte and acid-base changes which are complex in their origin, documented to be medically dangerous and this definitive treatment is necessary to help achieve a successful treatment outcome, and in need of definitive treatment as described herein. © 2016 Wiley Periodicals, Inc.

Sulfation of ceria-zirconia model automotive emissions control catalysts

NASA Astrophysics Data System (ADS)

Nelson, Alan Edwin

Cerium-zirconium mixed metal oxides are used in automotive emissions control catalysts to regulate the partial pressure of oxygen near the catalyst surface. The near surface oxygen partial pressure is regulated through transfer of atomic oxygen from the ceria-zirconia solid matrix to the platinum group metals to form metal oxides capable of oxidizing carbon monoxide and unburned hydrocarbons. Although the addition of zirconium in the cubic lattice of ceria increases the oxygen storage capacity and thermal stability of the ceria matrix, the cerium-zirconium oxide system remains particularly susceptible to deactivation from sulfur compounds. While the overall effect of sulfur on these systems is understood (partially irreversible deactivation), the fundamental and molecular interaction of sulfur with ceria-zirconia remains a challenging problem. Ceria-zirconia metal oxide solid solutions have been prepared through co-precipitation with nitrate precursors. The prepared powders were calcined and subsequently formed into planer wafers and characterized for chemical and physical attributes. The prepared samples were subsequently exposed to a sulfur dioxide based environment and characterized with spectroscopic techniques to characterize the extent of sulfation and the nature of surface sulfur species. The extent of sulfation of the model ceria-zirconia systems was characterized with Auger electron spectroscopy (AES) prior to and after treatment in a microreactor. Strong dependencies were observed between the atomic ratio of ceria to zirconia and the extent of sulfation. In addition, the partial pressure of sulfur dioxide during treatments also correlated to the extent of sulfation, while temperature only slightly effected the extent of sulfation. The AES data suggests the gas phase sulfur dioxide preferentially chemisorbs on surface ceria atoms and the extent of sulfation is heavily dependent on sulfur dioxide concentrations and only slightly dependent on catalyst

Synthesis and thermal stability of zirconia and yttria-stabilized zirconia microspheres.

PubMed

Leib, Elisabeth W; Vainio, Ulla; Pasquarelli, Robert M; Kus, Jonas; Czaschke, Christian; Walter, Nils; Janssen, Rolf; Müller, Martin; Schreyer, Andreas; Weller, Horst; Vossmeyer, Tobias

2015-06-15

Zirconia microparticles produced by sol-gel synthesis have great potential for photonic applications. To this end, identifying synthetic methods that yield reproducible control over size uniformity is important. Phase transformations during thermal cycling can disintegrate the particles. Therefore, understanding the parameters driving these transformations is essential for enabling high-temperature applications. Particle morphology is expected to influence particle processability and stability. Yttria-doping should improve the thermal stability of the particles, as it does in bulk zirconia. Zirconia and YSZ particles were synthesized by improved sol-gel approaches using fatty acid stabilizers. The particles were heated to 1500 °C, and structural and morphological changes were monitored by SEM, ex situ XRD and high-energy in situ XRD. Zirconia particles (0.4-4.3 μm in diameter, 5-10% standard deviation) synthesized according to the modified sol-gel approaches yielded significantly improved monodispersities. As-synthesized amorphous particles transformed to the tetragonal phase at ∼450 °C with a volume decrease of up to ∼75% and then to monoclinic after heating from ∼650 to 850 °C. Submicron particles disintegrated at ∼850 °C and microparticles at ∼1200 °C due to grain growth. In situ XRD revealed that the transition from the amorphous to tetragonal phase was accompanied by relief in microstrain and the transition from tetragonal to monoclinic was correlated with the tetragonal grain size. Early crystallization and smaller initial grain sizes, which depend on the precursors used for particle synthesis, coincided with higher stability. Yttria-doping reduced grain growth, stabilized the tetragonal phase, and significantly improved the thermal stability of the particles. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Overview of zirconia with respect to gas turbine applications

NASA Technical Reports Server (NTRS)

Cawley, J. D.

1984-01-01

Phase relationships and the mechanical properties of zirconia are examined as well as the thermal conductivity, deformation, diffusion, and chemical reactivity of this refractory material. Observations from the literature particular to plasma-sprayed material and implications for gas turbine engine applications are discussed. The literature review indicates that Mg-PSZ (partially stabilized zirconia) and Ca-PSZ are unsuitable for advanced gas turbine applications; a thorough characterization of the microstructure of plasma-sprayed zirconia is needed. Transformation-toughened zirconia may be suitable for use in monolithic components.

Acid-base and electrolyte disorders in patients with diabetes mellitus.

PubMed

Sotirakopoulos, Nikolaos; Kalogiannidou, Irini; Tersi, Maria; Armentzioiou, Karmen; Sivridis, Dimitrios; Mavromatidis, Konstantinos

2012-01-01

Diabetes mellitus is the most common metabolic disorder in the community. The diabetics may suffer from acid-base and electrolyte disorders due to complications of diabetes mellitus and the medication they receive. In this study, acid-base and electrolyte disorders were evaluated among outpatient diabetics in our hospital. The study consisted of patients with diabetes mellitus who visited the hospital as outpatients between the period January 1, 2004 to December 31, 2006. The patients' medical history, age and type of diabetes were noted, including whether they were taking diuretics and calcium channel blockers or not. Serum creatinine, proteins, sodium, potassium and chloride and blood gases were measured in all patients. Proteinuria was measured by 24-h urine collection. Two hundred and ten patients were divided in three groups based on the serum creatinine. Group A consisted of 114 patients that had serum creatinine < 1.2 mg/dL, group B consisted of 69 patients that had serum creatinine ranging from 1.3 to 3 mg/dL and group C consisted of 27 patients with serum creatinine > 3.1 mg/dL. Of the 210 patients, 176 had an acid-base disorder. The most common disorder noted in group A was metabolic alkalosis. In groups B and C, the common disorders were metabolic acidosis and alkalosis, and metabolic acidosis, respectively. The most common electrolyte disorders were hypernatremia (especially in groups A and B), hyponatremia (group C) and hyperkalemia (especially in groups B and C). It is concluded that: (a) in diabetic outpatients, acid-base and electrolyte disorders occurred often even if the renal function is normal, (b) the most common disorders are metabolic alkalosis and metabolic acidosis (the frequency increases with the deterioration of the renal function) and (c) the common electrolyte disorders are hypernatremia and hypokalemia.

Antagonist wear of monolithic zirconia crowns after 2 years.

PubMed

Lohbauer, Ulrich; Reich, Sven

2017-05-01

The aim of this study was to evaluate the amount of wear on the antagonist occlusal surfaces of clinically placed monolithic zirconia premolar and molar crowns (LAVA Plus, 3M ESPE). Fourteen in situ monolithic zirconia crowns and their opposing antagonists (n = 26) are the subject of an ongoing clinical trial and have been clinically examined at baseline and after 24 months. Silicone impressions were taken and epoxy replicas produced for qualitative SEM analysis and quantitative analysis using optical profilometry. Based on the baseline replicas, the follow-up situation has been scanned and digitally matched with the initial topography in order to calculate the mean volume loss (in mm 3 ) as well as the mean maximum vertical loss (in mm) after 2 years in service. The mean volume loss for enamel antagonist contacts (n = 7) was measured to 0.361 mm 3 and the mean of the maximum vertical loss to 0.204 mm. The mean volume loss for pure ceramic contacts (n = 10) was measured to 0.333 mm 3 and the mean of the maximum vertical loss to 0.145 mm. The wear rates on enamel contacts were not significantly different from those measured on ceramic antagonists. Based on the limitations of this study, it can be concluded for the monolithic zirconia material LAVA Plus that the measured wear rates are in consensus with other in vivo studies on ceramic restorations. Further, that no significant difference was found between natural enamel antagonists and ceramic restorations as antagonists. The monolithic zirconia restorations do not seem to be affected by wear within the first 2 years. The monolithic zirconia crowns (LAVA Plus) show acceptable antagonist wear rates after 2 years in situ, regardless of natural enamel or ceramics as antagonist materials.

A fractographic study of clinically retrieved zirconia-ceramic and metal-ceramic fixed dental prostheses.

PubMed

Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

2015-10-01

A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia-ceramic and metal-ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia-ceramic systems occurred more frequently than those in metal-ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Vinyl-polysiloxane impressions of 12 zirconia-ceramic and 6 metal-ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3±2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Among the 12 zirconia-ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal-ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Zirconia-ceramic and metal-ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia-ceramic FDPs relative to their metal-ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia-ceramic FDPs. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Nonflammable perfluoropolyether-based electrolytes for lithium batteries.

PubMed

Wong, Dominica H C; Thelen, Jacob L; Fu, Yanbao; Devaux, Didier; Pandya, Ashish A; Battaglia, Vincent S; Balsara, Nitash P; DeSimone, Joseph M

2014-03-04

The flammability of conventional alkyl carbonate electrolytes hinders the integration of large-scale lithium-ion batteries in transportation and grid storage applications. In this study, we have prepared a unique nonflammable electrolyte composed of low molecular weight perfluoropolyethers and bis(trifluoromethane)sulfonimide lithium salt. These electrolytes exhibit thermal stability beyond 200 °C and a remarkably high transference number of at least 0.91 (more than double that of conventional electrolytes). Li/LiNi1/3Co1/3Mn1/3O2 cells made with this electrolyte show good performance in galvanostatic cycling, confirming their potential as rechargeable lithium batteries with enhanced safety and longevity.

Nonflammable perfluoropolyether-based electrolytes for lithium batteries

PubMed Central

Wong, Dominica H. C.; Thelen, Jacob L.; Fu, Yanbao; Devaux, Didier; Pandya, Ashish A.; Battaglia, Vincent S.; Balsara, Nitash P.; DeSimone, Joseph M.

2014-01-01

The flammability of conventional alkyl carbonate electrolytes hinders the integration of large-scale lithium-ion batteries in transportation and grid storage applications. In this study, we have prepared a unique nonflammable electrolyte composed of low molecular weight perfluoropolyethers and bis(trifluoromethane)sulfonimide lithium salt. These electrolytes exhibit thermal stability beyond 200 °C and a remarkably high transference number of at least 0.91 (more than double that of conventional electrolytes). Li/LiNi1/3Co1/3Mn1/3O2 cells made with this electrolyte show good performance in galvanostatic cycling, confirming their potential as rechargeable lithium batteries with enhanced safety and longevity. PMID:24516123

Lithium air batteries having ether-based electrolytes

DOEpatents

Amine, Khalil; Curtiss, Larry A.; Lu, Jun; Lau, Kah Chun; Zhang, Zhengcheng; Sun, Yang-Kook

2016-10-25

A lithium-air battery includes a cathode including a porous active carbon material, a separator, an anode including lithium, and an electrolyte including a lithium salt and polyalkylene glycol ether, where the porous active carbon material is free of a metal-based catalyst.

Li-air batteries having ether-based electrolytes

DOEpatents

Amine, Khalil; Curtiss, Larry A; Lu, Jun; Lau, Kah Chun; Zhang, Zhengcheng; Sun, Yang-Kook

2015-03-03

A lithium-air battery includes a cathode including a porous active carbon material, a separator, an anode including lithium, and an electrolyte including a lithium salt and polyalkylene glycol ether, where the porous active carbon material is free of a metal-based catalyst.

Selection of new Kynar-based electrolytes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Christie, Alasdair M.; Christie, Lynn; Vincent, Colin A.

New electrolyte solution compositions have been identified for use in lithium-ion batteries after gelling with an appropriate quantity of Kynar polymer. Since the Li + conducting medium is largely the liquid electrolyte component, the assessment of these solutions as suitable lithium-ion cell candidates were investigated before adding the polymer. Selected electrolyte solutions were then used in the preparation of polymer gels. The specific conductivities of Kynar-based gels were determined as a function of salt concentration and polymer concentration. Optimised self-supporting polymer films, based on mixtures of ethylene carbonate (EC), ethylmethyl carbonate (EMC) and lithium hexafluorophosphate (LiPF 6) or lithium tetrafluoroborate (LiBF 4), showed good high current density cycling performance when used as separators in coke and Li 1- xMn 2O 4 (spinel) half-cells.

Electrolyte-gated transistors based on conducting polymer nanowire junction arrays.

PubMed

Alam, Maksudul M; Wang, Jun; Guo, Yaoyao; Lee, Stephanie P; Tseng, Hsian-Rong

2005-07-07

In this study, we describe the electrolyte gating and doping effects of transistors based on conducting polymer nanowire electrode junction arrays in buffered aqueous media. Conducting polymer nanowires including polyaniline, polypyrrole, and poly(ethylenedioxythiophene) were investigated. In the presence of a positive gate bias, the device exhibits a large on/off current ratio of 978 for polyaniline nanowire-based transistors; these values vary according to the acidity of the gate medium. We attribute these efficient electrolyte gating and doping effects to the electrochemically fabricated nanostructures of conducting polymer nanowires. This study demonstrates that two-terminal devices can be easily converted into three-terminal transistors by simply immersing the device into an electrolyte solution along with a gate electrode. Here, the field-induced modulation can be applied for signal amplification to enhance the device performance.

Functionally Graded Bismuth Oxide/Zirconia Bilayer Electrolytes for High-Performance Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs).

PubMed

Joh, Dong Woo; Park, Jeong Hwa; Kim, Doyeub; Wachsman, Eric D; Lee, Kang Taek

2017-03-15

A functionally graded Bi 1.6 Er 0.4 O 3 (ESB)/Y 0.16 Zr 0.84 O 1.92 (YSZ) bilayer electrolyte is successfully developed via a cost-effective screen printing process using nanoscale ESB powders on the tape-cast NiO-YSZ anode support. Because of the highly enhanced oxygen incorporation process at the cathode/electrolyte interface, a novel bilayer solid oxide fuel cell (SOFC) yields extremely high power density of ∼2.1 W cm -2 at 700 °C, which is a 2.4 times increase compared to that of the YSZ single electrolyte SOFC.

Process Developed for Generating Ceramic Interconnects With Low Sintering Temperatures for Solid Oxide Fuel Cells

NASA Technical Reports Server (NTRS)

Zhong, Zhi-Min; Goldsby, Jon C.

2005-01-01

Solid oxide fuel cells (SOFCs) have been considered as premium future power generation devices because they have demonstrated high energy-conversion efficiency, high power density, and extremely low pollution, and have the flexibility of using hydrocarbon fuel. The Solid-State Energy Conversion Alliance (SECA) initiative, supported by the U.S. Department of Energy and private industries, is leading the development and commercialization of SOFCs for low-cost stationary and automotive markets. The targeted power density for the initiative is rather low, so that the SECA SOFC can be operated at a relatively low temperature (approx. 700 C) and inexpensive metallic interconnects can be utilized in the SOFC stack. As only NASA can, the agency is investigating SOFCs for aerospace applications. Considerable high power density is required for the applications. As a result, the NASA SOFC will be operated at a high temperature (approx. 900 C) and ceramic interconnects will be employed. Lanthanum chromite-based materials have emerged as a leading candidate for the ceramic interconnects. The interconnects are expected to co-sinter with zirconia electrolyte to mitigate the interface electric resistance and to simplify the processing procedure. Lanthanum chromites made by the traditional method are sintered at 1500 C or above. They react with zirconia electrolytes (which typically sinter between 1300 and 1400 C) at the sintering temperature of lanthanum chromites. It has been envisioned that lanthanum chromites with lower sintering temperatures can be co-fired with zirconia electrolyte. Nonstoichiometric lanthanum chromites can be sintered at lower temperatures, but they are unstable and react with zirconia electrolyte during co-sintering. NASA Glenn Research Center s Ceramics Branch investigated a glycine nitrate process to generate fine powder of the lanthanum-chromite-based materials. By simultaneously doping calcium on the lanthanum site, and cobalt and aluminum on the

A plasticized polymer-electrolyte-based photoelectrochemical solar cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, D.; Ibrahim, M.A.; Frank, A.J.

1998-01-01

A photoelectrochemical solar cell based on an n-GaAs/polymer-redox-electrolyte junction is reported. Di(ethylene glycol) ethyl ether acrylate containing ferrocene as a redox species and benzoin methyl ether as a photoinitiator is polymerized in situ. Propylene carbonate is used as a plasticizer to improve the conductivity of the polymer redox electrolyte. For thin (1 {micro}m) polymer electrolytes, the series resistance of the cell is negligible. However, the short-circuit photocurrent density of the cell at light intensities above 10 mW/cm{sup 2} is limited by mass transport of redox species within the polymer matrix. At a light intensity of 70 mW/cm{sup 2}, a moderatemore » light-to-electrical energy conversion efficiency (3.1%) is obtained. The interfacial charge-transfer properties of the cell in the dark and under illumination are studied.« less

Preparation and Characterization of Anode-Supported YSZ Thin Film Electrolyte by Co-Tape Casting and Co-Sintering Process

NASA Astrophysics Data System (ADS)

Liu, Q. L.; Fu, C. J.; Chan, S. H.; Pasciak, G.

2011-06-01

In this study, a co-tape casting and co-sintering process has been developed to prepare yttria-stabilized zirconia (YSZ) electrolyte films supported on Ni-YSZ anode substrates in order to substantially reduce the fabrication cost of solid oxide fuel cells (SOFC). Through proper control of the process, the anode/electrolyte bilayer structures with a size of 7.8cm × 7.8cm were achieved with good flatness. Scanning electron microscopy (SEM) observation indicated that the YSZ electrolyte film was about 16 μm in thickness, highly dense, crack free and well-bonded to the anode support. The electrochemical properties of the prepared anode-supported electrolyte film was evaluated in a button cell mode incorporating a (LaSr)MnO3-YSZ composite cathode. With humidified hydrogen as the fuel and stationary air as the oxidant, the cell demonstrated an open-circuit voltage of 1.081 V and a maximum power density of 1.01 W/cm2 at 800°C. The obtained results represent the important progress in the development of anode-supported intermediate temperature SOFC with reduced fabrication cost.

Assessment of Lithium-based Battery Electrolytes Developed under the NASA PERS Program

NASA Technical Reports Server (NTRS)

Bennett, William R.; Baldwin, Richard S.

2006-01-01

Recently, NASA formally completed the Polymer Energy Rechargeable System (PERS) Program, which was established in 2000 in collaboration with the Air Force Research Laboratory (AFRL) to support the development of polymer-based, lithium-based cell chemistries and battery technologies to address the next generation of aerospace applications and mission needs. The goal of this program was to ultimately develop an advanced, space-qualified battery technology, which embodied a solid polymer electrolyte (SPE) and complementary components, with improved performance characteristics that would address future aerospace battery requirements. Programmatically, the PERS initiative exploited both interagency collaborations to address common technology and engineering issues and the active participation of academia and private industry. The initial program phases focused on R&D activities to address the critical technical issues and challenges at the cell level. A variety of cell and polymeric electrolyte concepts were pursued as part of the development efforts undertaken at numerous governmental, industrial and academic laboratories. Numerous candidate electrolyte materials were developed, synthesized and optimized for evaluation. Utilizing the component screening facility and the "standardized" test procedures developed at the NASA Glenn Research Center, electrochemical screening and performance evaluations of promising candidate materials were completed. This overview summarizes test results for a variety of candidate electrolyte materials that were developed under the PERS Program. Electrolyte properties are contrasted and compared to the original project goals, and the strengths and weaknesses of the electrolyte chemistries are discussed. Limited cycling data for full-cells using lithium metal and vanadium oxide electrodes are also presented. Based on measured electrolyte properties, the projected performance characteristics and temperature limitations of batteries utilizing

Synthesis of zirconia (ZrO2) nanowires via chemical vapor deposition

NASA Astrophysics Data System (ADS)

Baek, M. K.; Park, S. J.; Choi, D. J.

2017-02-01

Monoclinic zirconia nanowires were synthesized by chemical vapor deposition using ZrCl4 powder as a starting material at 1200 °C and 760 Torr. Graphite was employed as a substrate, and an Au thin film was pre-deposited on the graphite as a catalyst. The zirconia nanostructure morphology was observed through scanning electron microscopy and transmission electron microscopy. Based on X-ray diffraction, selected area electron diffraction, and Raman spectroscopy data, the resulting crystal structure was found to be single crystalline monoclinic zirconia. The homogeneous distributions of Zr, O and Au were studied by scanning transmission electron microscopy with energy dispersive X-ray spectroscopy mapping, and there was no metal droplet at the nanowire tips despite the use of an Au metal catalyst. This result is apart from that of conventional metal catalyzed nanowires.

Comparison of bond strengths of ceramic brackets bonded to zirconia surfaces using different zirconia primers and a universal adhesive.

PubMed

Lee, Ji-Yeon; Ahn, Jaechan; An, Sang In; Park, Jeong-Won

2018-02-01

The aim of this study is to compare the shear bond strengths of ceramic brackets bonded to zirconia surfaces using different zirconia primers and universal adhesive. Fifty zirconia blocks (15 × 15 × 10 mm, Zpex, Tosoh Corporation) were polished with 1,000 grit sand paper and air-abraded with 50 µm Al 2 O 3 for 10 seconds (40 psi). They were divided into 5 groups: control (CO), Metal/Zirconia primer (MZ, Ivoclar Vivadent), Z-PRIME Plus (ZP, Bisco), Zirconia Liner (ZL, Sun Medical), and Scotchbond Universal adhesive (SU, 3M ESPE). Transbond XT Primer (used for CO, MZ, ZP, and ZL) and Transbond XT Paste was used for bracket bonding (Gemini clear ceramic brackets, 3M Unitek). After 24 hours at 37°C storage, specimens underwent 2,000 thermocycles, and then, shear bond strengths were measured (1 mm/min). An adhesive remnant index (ARI) score was calculated. The data were analyzed using one-way analysis of variance and the Bonferroni test ( p = 0.05). Surface treatment with primers resulted in increased shear bond strength. The SU group showed the highest shear bond strength followed by the ZP, ZL, MZ, and CO groups, in that order. The median ARI scores were as follows: CO = 0, MZ = 0, ZP = 0, ZL = 0, and SU = 3 ( p < 0.05). Within this experiment, zirconia primer can increase the shear bond strength of bracket bonding. The highest shear bond strength is observed in SU group, even when no primer is used.

Comparison of bond strengths of ceramic brackets bonded to zirconia surfaces using different zirconia primers and a universal adhesive

PubMed Central

2018-01-01

Objectives The aim of this study is to compare the shear bond strengths of ceramic brackets bonded to zirconia surfaces using different zirconia primers and universal adhesive. Materials and Methods Fifty zirconia blocks (15 × 15 × 10 mm, Zpex, Tosoh Corporation) were polished with 1,000 grit sand paper and air-abraded with 50 µm Al2O3 for 10 seconds (40 psi). They were divided into 5 groups: control (CO), Metal/Zirconia primer (MZ, Ivoclar Vivadent), Z-PRIME Plus (ZP, Bisco), Zirconia Liner (ZL, Sun Medical), and Scotchbond Universal adhesive (SU, 3M ESPE). Transbond XT Primer (used for CO, MZ, ZP, and ZL) and Transbond XT Paste was used for bracket bonding (Gemini clear ceramic brackets, 3M Unitek). After 24 hours at 37°C storage, specimens underwent 2,000 thermocycles, and then, shear bond strengths were measured (1 mm/min). An adhesive remnant index (ARI) score was calculated. The data were analyzed using one-way analysis of variance and the Bonferroni test (p = 0.05). Results Surface treatment with primers resulted in increased shear bond strength. The SU group showed the highest shear bond strength followed by the ZP, ZL, MZ, and CO groups, in that order. The median ARI scores were as follows: CO = 0, MZ = 0, ZP = 0, ZL = 0, and SU = 3 (p < 0.05). Conclusions Within this experiment, zirconia primer can increase the shear bond strength of bracket bonding. The highest shear bond strength is observed in SU group, even when no primer is used. PMID:29487838

Flexible thin-film battery based on solid-like ionic liquid-polymer electrolyte

NASA Astrophysics Data System (ADS)

Li, Qin; Ardebili, Haleh

2016-01-01

The development of high-performance flexible batteries is imperative for several contemporary applications including flexible electronics, wearable sensors and implantable medical devices. However, traditional organic liquid-based electrolytes are not ideal for flexible batteries due to their inherent safety and stability issues. In this study, a non-volatile, non-flammable and safe ionic liquid (IL)-based polymer electrolyte film with solid-like feature is fabricated and incorporated in a flexible lithium ion battery. The ionic liquid is 1-Ethyl-3-methylimidazolium dicyanamide (EMIMDCA) and the polymer is composed of poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP). The electrolyte exhibits good thermal stability (i.e. no weight loss up to 300 °C) and relatively high ionic conductivity (6 × 10-4 S cm-1). The flexible thin-film lithium ion battery based on solid-like electrolyte film is encapsulated using a thermal-lamination process and demonstrates excellent electrochemical performance, in both flat and bent configurations.

Molecular interactions in high conductive gel electrolytes based on low molecular weight gelator.

PubMed

Bielejewski, Michał; Łapiński, Andrzej; Demchuk, Oleg

2017-03-15

Organic ionic gel (OIG) electrolytes, also known as gel electrolytes or ionogels are one example of modern functional materials with the potential to use in wide range of electrochemical applications. The functionality of OIGs arises from the thermally reversible solidification of electrolytes or ionic liquids and their superior ionic conductivity. To understand and to predict the properties of these systems it is important to get the knowledge about the interactions on molecular level between the solid gelator matrix and the electrolyte solution. This paper reports the spectroscopic studies (FT-IR, UV-Vis and Raman) of the gel electrolyte based on low molecular weight gelator methyl-4,6-O-(p-nitrobenzylidene)-α-d-glucopyranoside and solution of quaternary ammonium salt, tetramethylammonium bromide. The solidification process was based on sol-gel technique. Below characteristic temperature, defined as gel to sol phase transition temperature, T gs , the samples were solid-like and showed high conductivity values of the same order as observed for pure liquid electrolytes. The investigations were performed for a OIGs in a wide range of molar concentrations of the electrolyte solution. Copyright © 2016 Elsevier Inc. All rights reserved.

Shear bond strength of a denture base acrylic resin and gingiva-colored indirect composite material to zirconia ceramics.

PubMed

Kubochi, Kei; Komine, Futoshi; Fushiki, Ryosuke; Yagawa, Shogo; Mori, Serina; Matsumura, Hideo

2017-04-01

To evaluate the shear bond strengths of two gingiva-colored materials (an indirect composite material and a denture base acrylic resin) to zirconia ceramics and determine the effects of surface treatment with various priming agents. A gingiva-colored indirect composite material (CER) or denture base acrylic resin (PAL) was bonded to zirconia disks with unpriming (UP) or one of seven priming agents (n=11 each), namely, Alloy Primer (ALP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Act), Metal Link (MEL), Meta Fast Bonding Liner (MFB), MR. bond (MRB), and V-Primer (VPR). Shear bond strength was determined before and after 5000 thermocycles. The data were analyzed with the Kruskal-Wallis test and Steel-Dwass test. The mean pre-/post-thermalcycling bond strengths were 1.0-14.1MPa/0.1-12.1MPa for the CER specimen and 0.9-30.2MPa/0.1-11.1MPa for the PAL specimen. For the CER specimen, the ALP, CPB, and CPB+Act groups had significantly higher bond strengths among the eight groups, at both 0 and 5000 thermocycles. For the PAL specimen, shear bond strength was significantly lower after thermalcycling in all groups tested. After 5000 thermocycles, bond strengths were significantly higher in the CPB and CPB+Act groups than in the other groups. For the PAL specimens, bond strengths were significantly lower after thermalcycling in all groups tested. The MDP functional monomer improved bonding of a gingiva-colored indirect composite material and denture base acrylic resin to zirconia ceramics. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Crystallization stabilization mechanism of yttria-doped zirconia by hydrothermal treatment of mechanical mixtures of zirconia xerogel and crystalline yttria

NASA Astrophysics Data System (ADS)

Dell'Agli, G.; Mascolo, G.; Mascolo, M. C.; Pagliuca, C.

2005-06-01

Mechanical mixtures of zirconia xerogel and crystalline Y 2O 3 were hydrothermally treated by microwave and traditional route, respectively. Some mixtures were used either as powders form or as cylindrical compacts isostatically pressed at 150 MPa. The microwave-hydrothermal treatments were performed at 110, 150 and 200 °C for reaction times up to 2 h, whereas the traditional hydrothermal treatments were performed at 110 °C at increasing reaction times up to 7 days. All the treatments were performed in the presence of diluted (0.2 M) or concentrated (2.0 M) solution of (K 2CO 3+KOH) mineralizer. The crystallization-stabilization mechanism of synthesized Y-based zirconia powders and the reaction times for the full crystallization at the low temperature of hydrothermal treatments are discussed.

Synthesis of Mesoporous Nanocrystalline Zirconia by Surfactant-Assisted Hydrothermal Approach.

PubMed

Nath, Soumav; Biswas, Ashik; Kour, Prachi P; Sarma, Loka S; Sur, Ujjal Kumar; Ankamwar, Balaprasad G

2018-08-01

In this paper, we have reported the chemical synthesis of thermally stable mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted hydrothermal approach. We have employed different type of surfactants such as CTAB, SDS and Triton X-100 in our synthesis. The synthesized nanocrystalline zirconia multistructures exhibit various morphologies such as rod, mortar-pestle with different particle sizes. We have characterized the zirconia multistructures by X-ray diffraction study, Field emission scanning electron microscopy, Attenuated total refection infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The thermal stability of as synthesized zirconia multistructures was studied by thermo gravimetric analysis, which shows the high thermal stability of nanocrystalline zirconia around 900 °C temperature.

On the interfacial fracture of porcelain/zirconia and graded zirconia dental structures.

PubMed

Chai, Herzl; Lee, James J-W; Mieleszko, Adam J; Chu, Stephen J; Zhang, Yu

2014-08-01

Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bending fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a finite-element analysis taking into account stress-shielding effects due to the presence of adjacent channel cracks. The resulting GC was considerably less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred via a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good esthetic quality, graded Y-TZP emerges as a viable material concept for dental restorations. Copyright © 2014 Acta Materialia Inc. All rights reserved.

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro

PubMed Central

Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J.; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

2013-01-01

Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO2) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential. PMID:28788415

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro.

PubMed

Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

2013-12-04

Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro . Four implant biomaterials were incubated with Enterococcus faecalis , Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO₂) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO₂ coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential.

Long-term Bond Strength between Layering Indirect Composite Material and Zirconia Coated with Silicabased Ceramics.

PubMed

Fushiki, Ryosuke; Komine, Futoshi; Honda, Junichi; Kamio, Shingo; Blatz, Markus B; Matsumura, Hideo

2015-06-01

This study evaluated the long-term shear bond strength between an indirect composite material and a zirconia framework coated with silica-based ceramics, taking the effect of different primers into account. A total of 165 airborne-particle abraded zirconia disks were subjected to one of three pretreatments: no pretreatment (ZR-AB), airborne-particle abrasion of zirconia coated with feldspathic porcelain (ZR-PO-AB), and 9.5% hydrofluoric acid etching of zirconia coated with feldspathic porcelain (ZR-PO-HF). An indirect composite material (Estenia C&B) was then bonded to the zirconia disks after they were treated with one of the following primers: Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid B (PLB), or no priming (CON, control group). Shear bond strength was tested after 100,000 thermocycles, and the data were analyzed using the Steel-Dwass U-test (α = 0.05). For ZR-PO-AB and ZR-PO-HF specimens, bond strength was highest in the CPB+Activator group (25.8 MPa and 22.4 MPa, respectively). Bond strengths were significantly lower for ZR-AB specimens in the CON and PLB groups and for ZR-PO-AB specimens in the CON, CPB, and EOP groups. Combined application of a hydrophobic phosphate monomer (MDP) and silane coupling agent enhanced the long-term bond strength of indirect composite material to a zirconia coated with silica-based ceramics.

Optical properties of pre-colored dental monolithic zirconia ceramics.

PubMed

Kim, Hee-Kyung; Kim, Sung-Hun

2016-12-01

The purposes of this study were to evaluate the optical properties of recently marketed pre-colored monolithic zirconia ceramics and to compare with those of veneered zirconia and lithium disilicate glass ceramics. Various shades of pre-colored monolithic zirconia, veneered zirconia, and lithium disilicate glass ceramic specimens were tested (17.0×17.0×1.5mm, n=5). CIELab color coordinates were obtained against white, black, and grey backgrounds with a spectrophotometer. Color differences of the specimen pairs were calculated by using the CIEDE2000 (ΔE 00 ) formula. The translucency parameter (TP) was derived from ΔE 00 of the specimen against a white and a black background. X-ray diffraction was used to determine the crystalline phases of monolithic zirconia specimens. Data were analyzed with 1-way ANOVA, Scheffé post hoc, and Pearson correlation testing (α=0.05). For different shades of the same ceramic brand, there were significant differences in L * , a * , b * , and TP values in most ceramic brands. With the same nominal shade (A2), statistically significant differences were observed in L * , a * , b * , and TP values among different ceramic brands and systems (P<0.001). The color differences between pre-colored monolithic zirconia and veneered zirconia or lithium disilicate glass ceramics of the corresponding nominal shades ranged beyond the acceptability threshold. Due to the high L * values and low a * and b * values, pre-colored monolithic zirconia ceramics can be used with additional staining to match neighboring restorations or natural teeth. Due to their high value and low chroma, unacceptable color mismatch with adjacent ceramic restorations might be expected. Copyright © 2016 Elsevier Ltd. All rights reserved.

SEM evaluation of human gingival fibroblasts growth onto CAD/CAM zirconia and veneering ceramic for zirconia

PubMed Central

Zizzari, Vincenzo; Borelli, Bruna; De Colli, Marianna; Tumedei, Margherita; Di Iorio, Donato; Zara, Susi; Sorrentino, Roberto; Cataldi, Amelia; Gherlone, Enrico Felice; Zarone, Fernando; Tetè, Stefano

2013-01-01

Summary Aim To evaluate the growth of Human Gingival Fibroblasts (HGFs) cultured onto sample discs of CAD/CAM zirconia and veneering ceramic for zirconia by means of Scanning Electron Microscope (SEM) analysis at different experimental times. Methods A total of 26 experimental discs, divided into 2 groups, were used: Group A) CAD/CAM zirconia (3Y-TZP) discs (n=13); Group B) veneering ceramic for zirconia discs (n=13). HGFs were obtained from human gingival biopsies, isolated and placed in culture plates. Subsequently, cells were seeded on experimental discs at 7,5×103/cm2 concentration and cultured for a total of 7 days. Discs were processed for SEM observation at 3h, 24h, 72h and 7 days. Results In Group A, after 3h, HGFs were adherent to the surface and showed a flattened profile. The disc surface covered by HGFs resulted to be wider in Group A than in Group B samples. At SEM observation, after 24h and 72h, differences in cell attachment were slightly noticeable between the groups, with an evident flattening of HGFs on both surfaces. All differences between Group A and group B became less significant after 7 days of culture in vitro. Conclusions SEM analysis of HGFs showed differences in terms of cell adhesion and proliferation, especially in the early hours of culture. Results showed a better adhesion and cell growth in Group A than in Group B, especially up to 72h in vitro. Differences decreased after 7 days, probably because of the rougher surface of CAD/CAM zirconia, promoting better cell adhesion, compared to the smoother surface of veneering ceramic. PMID:24611089

A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

NASA Technical Reports Server (NTRS)

Baldwin, Richard S.; Bennett, William R.

2007-01-01

The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

An overview of zirconia ceramics: basic properties and clinical applications.

PubMed

Manicone, Paolo Francesco; Rossi Iommetti, Pierfrancesco; Raffaelli, Luca

2007-11-01

Zirconia (ZrO2) is a ceramic material with adequate mechanical properties for manufacturing of medical devices. Zirconia stabilized with Y2O3 has the best properties for these applications. When a stress occurs on a ZrO2 surface, a crystalline modification opposes the propagation of cracks. Compression resistance of ZrO2 is about 2000 MPa. Orthopedic research led to this material being proposed for the manufacture of hip head prostheses. Prior to this, zirconia biocompatibility had been studied in vivo; no adverse responses were reported following the insertion of ZrO2 samples into bone or muscle. In vitro experimentation showed absence of mutations and good viability of cells cultured on this material. Zirconia cores for fixed partial dentures (FPD) on anterior and posterior teeth and on implants are now available. Clinical evaluation of abutments and periodontal tissue must be performed prior to their use. Zirconia opacity is very useful in adverse clinical situations, for example, for masking of dischromic abutment teeth. Radiopacity can aid evaluation during radiographic controls. Zirconia frameworks are realized by using computer-aided design/manufacturing (CAD/CAM) technology. Cementation of Zr-ceramic restorations can be performed with adhesive luting. Mechanical properties of zirconium oxide FPDs have proved superior to those of other metal-free restorations. Clinical evaluations, which have been ongoing for 3 years, indicate a good success rate for zirconia FPDs. Zirconia implant abutments can also be used to improve the aesthetic outcome of implant-supported rehabilitations. Newly proposed zirconia implants seem to have good biological and mechanical properties; further studies are needed to validate their application.

Phase field modeling of tetragonal to monoclinic phase transformation in zirconia

NASA Astrophysics Data System (ADS)

Mamivand, Mahmood

Zirconia based ceramics are strong, hard, inert, and smooth, with low thermal conductivity and good biocompatibility. Such properties made zirconia ceramics an ideal material for different applications form thermal barrier coatings (TBCs) to biomedicine applications like femoral implants and dental bridges. However, this unusual versatility of excellent properties would be mediated by the metastable tetragonal (or cubic) transformation to the stable monoclinic phase after a certain exposure at service temperatures. This transformation from tetragonal to monoclinic, known as LTD (low temperature degradation) in biomedical application, proceeds by propagation of martensite, which corresponds to transformation twinning. As such, tetragonal to monoclinic transformation is highly sensitive to mechanical and chemomechanical stresses. It is known in fact that this transformation is the source of the fracture toughening in stabilized zirconia as it occurs at the stress concentration regions ahead of the crack tip. This dissertation is an attempt to provide a kinetic-based model for tetragonal to monoclinic transformation in zirconia. We used the phase field technique to capture the temporal and spatial evolution of monoclinic phase. In addition to morphological patterns, we were able to calculate the developed internal stresses during tetragonal to monoclinic transformation. The model was started form the two dimensional single crystal then was expanded to the two dimensional polycrystalline and finally to the three dimensional single crystal. The model is able to predict the most physical properties associated with tetragonal to monoclinic transformation in zirconia including: morphological patterns, transformation toughening, shape memory effect, pseudoelasticity, surface uplift, and variants impingement. The model was benched marked with several experimental works. The good agreements between simulation results and experimental data, make the model a reliable tool for

Shear bond strength between resin cement and colored zirconia made with metal chlorides.

PubMed

Kim, Ga-Hyun; Park, Sang-Won; Lee, Kwangmin; Oh, Gye-Jeong; Lim, Hyun-Pil

2015-06-01

Although the application of zirconia in esthetic prostheses has increased, the shear bond strength (SBS) between colored zirconia and resin cement has not been investigated. The purpose of this study was to compare the SBS between resin cement and colored zirconia made with metal chlorides. Sixty-four zirconia specimens were divided into 2 groups: one in which the specimens were bonded with resin cement, including 4-META (4-methacryloxyethyl trimellitic anhydride), and one in which the specimens were bonded with resin cement (SEcure, Sun Medical) after being processed with zirconia primer (Zirconia Liner), including 4-META. Each group was then divided into 4 subgroups depending on the coloring liquid. The subgroups were noncolored (control), commercial coloring liquid VITA In-Ceram 2000 YZ LL1, aqueous chromium chloride solution 0.1 wt%, and aqueous molybdenum chloride solution 0.1 wt%. Composite resin cylinders (Filtek Z250, 3M ESPE) were fabricated and bonded to the surface of the zirconia specimen with resin cement (SEcure). All specimens were stored in 37°C distilled water for 24 hours, and the SBS was measured with a universal testing machine. All data were analyzed statistically with 2-way ANOVA and tested post hoc with the Tukey test (α=.05). Significant differences were observed among the SBS values of the colored zirconia depending on the coloring liquid (P<.001) and whether they were processed with zirconia primer (P<.001). The SBS between colored zirconia and resin cement was significantly higher than that of noncolored zirconia and resin cement in groups processed with zirconia primer (P<.05). Colored zirconia immersed in aqueous molybdenum chloride solution showed a significantly higher SBS. Coloring liquid enhanced the SBS between resin cement and zirconia processed with zirconia primer. In particular, colored zirconia immersed in aqueous molybdenum chloride solution showed the highest SBS. Copyright © 2015 Editorial Council for the Journal of

Chemical interaction mechanism of 10-MDP with zirconia

PubMed Central

Nagaoka, Noriyuki; Yoshihara, Kumiko; Feitosa, Victor Pinheiro; Tamada, Yoshiyuki; Irie, Masao; Yoshida, Yasuhiro; Van Meerbeek, Bart; Hayakawa, Satoshi

2017-01-01

Currently, the functional monomer 10-methacryloyloxy-decyl-dihydrogen-phosphate (10-MDP) was documented to chemically bond to zirconia ceramics. However, little research has been conducted to unravel the underlying mechanisms. This study aimed to assess the chemical interaction and to demonstrate the mechanisms of coordination between 10-MDP and zirconium oxide using 1H and 31P magic angle spinning (MAS) nuclear magnetic resonance (NMR) and two dimensional (2D) 1H → 31P heteronuclear correlation (HETCOR) NMR. In addition, shear bond-strength (SBS) tests were conducted to determine the effect of 10-MDP concentration on the bonding effectiveness to zirconia. These SBS tests revealed a 10-MDP concentration-dependent SBS with a minimum of 1-ppb 10-MDP needed. 31P-NMR revealed that one P-OH non-deprotonated of the PO3H2 group from 10-MDP chemically bonded strongly to zirconia. 1H-31P HETCOR NMR indicated that the 10-MDP monomer can be adsorbed onto the zirconia particles by hydrogen bonding between the P=O and Zr-OH groups or via ionic interactions between partially positive Zr and deprotonated 10-MDP (P-O−). The combination of 1H NMR and 2D 1H-31P HETCOR NMR enabled to describe the different chemical states of the 10-MDP bonds with zirconia; they not only revealed ionic but also hydrogen bonding between 10-MDP and zirconia. PMID:28358121

Bonding effectiveness to different chemically pre-treated dental zirconia.

PubMed

Inokoshi, Masanao; Poitevin, André; De Munck, Jan; Minakuchi, Shunsuke; Van Meerbeek, Bart

2014-09-01

The objective of this study was to evaluate the effect of different chemical pre-treatments on the bond durability to dental zirconia. Fully sintered IPS e.max ZirCAD (Ivoclar Vivadent) blocks were subjected to tribochemical silica sandblasting (CoJet, 3M ESPE). The zirconia samples were additionally pre-treated using one of four zirconia primers/adhesives (Clearfil Ceramic Primer, Kuraray Noritake; Monobond Plus, Ivoclar Vivadent; Scotchbond Universal, 3M ESPE; Z-PRIME Plus, Bisco). Finally, two identically pre-treated zirconia blocks were bonded together using composite cement (RelyX Ultimate, 3M ESPE). The specimens were trimmed at the interface to a cylindrical hourglass and stored in distilled water (7 days, 37 °C), after which they were randomly tested as is or subjected to mechanical ageing involving cyclic tensile stress (10 N, 10 Hz, 10,000 cycles). Subsequently, the micro-tensile bond strength was determined, and SEM fractographic analysis performed. Weibull analysis revealed the highest Weibull scale and shape parameters for the 'Clearfil Ceramic Primer/mechanical ageing' combination. Chemical pre-treatment of CoJet (3M ESPE) sandblasted zirconia using Clearfil Ceramic Primer (Kuraray Noritake) and Monobond Plus (Ivoclar Vivadent) revealed a significantly higher bond strength than when Scotchbond Universal (3M ESPE) and Z-PRIME Plus (Bisco) were used. After ageing, Clearfil Ceramic Primer (Kuraray Noritake) revealed the most stable bond durability. Combined mechanical/chemical pre-treatment, the latter with either Clearfil Ceramic Primer (Kuraray Noritake) or Monobond Plus (Ivoclar Vivadent), resulted in the most durable bond to zirconia. As a standard procedure to durably bond zirconia to tooth tissue, the application of a combined 10-methacryloyloxydecyl dihydrogen phosphate/silane ceramic primer to zirconia is clinically highly recommended.

Osteogenic Responses to Zirconia with Hydroxyapatite Coating by Aerosol Deposition

PubMed Central

Cho, Y.; Hong, J.; Ryoo, H.; Kim, D.; Park, J.

2015-01-01

Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. PMID:25586588

Neurologic complications of electrolyte disturbances and acid-base balance.

PubMed

Espay, Alberto J

2014-01-01

Electrolyte and acid-base disturbances are common occurrences in daily clinical practice. Although these abnormalities can be readily ascertained from routine laboratory findings, only specific clinical correlates may attest as to their significance. Among a wide phenotypic spectrum, acute electrolyte and acid-base disturbances may affect the peripheral nervous system as arreflexic weakness (hypermagnesemia, hyperkalemia, and hypophosphatemia), the central nervous system as epileptic encephalopathies (hypomagnesemia, dysnatremias, and hypocalcemia), or both as a mixture of encephalopathy and weakness or paresthesias (hypocalcemia, alkalosis). Disabling complications may develop not only when these derangements are overlooked and left untreated (e.g., visual loss from intracranial hypertension in respiratory or metabolic acidosis; quadriplegia with respiratory insufficiency in hypermagnesemia) but also when they are inappropriately managed (e.g., central pontine myelinolisis when rapidly correcting hyponatremia; cardiac arrhythmias when aggressively correcting hypo- or hyperkalemia). Therefore prompt identification of the specific neurometabolic syndromes is critical to correct the causative electrolyte or acid-base disturbances and prevent permanent central or peripheral nervous system injury. This chapter reviews the pathophysiology, clinical investigations, clinical phenotypes, and current management strategies in disorders resulting from alterations in the plasma concentration of sodium, potassium, calcium, magnesium, and phosphorus as well as from acidemia and alkalemia. © 2014 Elsevier B.V. All rights reserved.

New Supercapacitors Based on the Synergetic Redox Effect between Electrode and Electrolyte

PubMed Central

Zhang, You; Cui, Xiuguo; Zu, Lei; Cai, Xiaomin; Liu, Yang; Wang, Xiaodong; Lian, Huiqin

2016-01-01

Redox electrolytes can provide significant enhancement of capacitance for supercapacitors. However, more important promotion comes from the synergetic effect and matching between the electrode and electrolyte. Herein, we report a novel electrochemical system consisted of a polyanilline/carbon nanotube composite redox electrode and a hydroquinone (HQ) redox electrolyte, which exhibits a specific capacitance of 7926 F/g in a three-electrode system when the concentration of HQ in H2SO4 aqueous electrolyte is 2 mol/L, and the maximum energy density of 114 Wh/kg in two-electrode symmetric configuration. Moreover, the specific capacitance retention of 96% after 1000 galvanostatic charge/discharge cycles proves an excellent cyclic stability. These ultrahigh performances of the supercapacitor are attributed to the synergistic effect both in redox polyanilline-based electrolyte and the redox hydroquinone electrode. PMID:28773855

Electric current-producing device having sulfone-based electrolyte

DOEpatents

Angell, Charles Austen; Sun, Xiao-Guang

2010-11-16

Electrolytic solvents and applications of such solvents including electric current-producing devices. For example, a solvent can include a sulfone compound of R1--SO2--R2, with R1 being an alkyl group and R2 a partially oxygenated alkyl group, to exhibit high chemical and thermal stability and high oxidation resistance. For another example, a battery can include, between an anode and a cathode, an electrolyte which includes ionic electrolyte salts and a non-aqueous electrolyte solvent which includes a non-symmetrical, non-cyclic sulfone. The sulfone has a formula of R1--SO2--R2, wherein R1 is a linear or branched alkyl or partially or fully fluorinated linear or branched alkyl group having 1 to 7 carbon atoms, and R2 is a linear or branched or partially or fully fluorinated linear or branched oxygen containing alkyl group having 1 to 7 carbon atoms. The electrolyte can include an electrolyte co-solvent and an electrolyte additive for protective layer formation.

[Measurement of chromaticity of five hued zirconia].

PubMed

Wen, Ning; Shao, Long-quan; Yi, Yuan-fu; Deng, Bin; Liu, Hong-chen

2009-05-01

To determine the chroma value of sintered IL1-IL5 zirconia materials in comparison with the Vita In-Ceram YZ color shade. Five types of shading dental zirconia ceramics with color gradient were prepared by adding Fe2O3, CeO2, and Bi2O3 to the zirconia powder, and their chroma values were determined using a spectrophotometer and the color difference was calculated. The chroma value ranges were L: 67.76-77.78, a: -2.19-3.80, and b: 12.13-25.01. Slight deltaE was found between IL1 and LL1, IL2 and LL2, and IL3 and LL3. The deltaE between IL4 and LL4 could be compensated by veneering porcelain, whereas deltaL between IL5 and LL5 could not be compensated in this manner. Shading dental zirconia ceramics can be prepared by addition of metal oxides with color similar to the Vita In-Ceram YZ color shades to match that of the veneering porcelain in clinical practice.

Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors

NASA Astrophysics Data System (ADS)

Gómez, A.; Villanueva, R.; Vie, D.; Murcia-Mascaros, S.; Martínez, E.; Beltrán, A.; Sapiña, F.; Vicent, M.; Sánchez, E.

2013-01-01

Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10-15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition, Rietveld refinement of the XRD profiles of selected samples allows detecting the coexistence of the tetragonal and the cubic phases for high doping concentration and high thermal treatment temperatures. Raman experiments suggest the presence of both phases also at relatively low treatment temperatures.

Positron annihilation studies of zirconia doped with metal cations of different valence

NASA Astrophysics Data System (ADS)

Prochazka, I.; Cizek, J.; Melikhova, O.; Konstantinova, T. E.; Danilenko, I. A.; Yashchishyn, I. A.; Anwand, W.; Brauer, G.

2013-06-01

New results obtained by applying positron annihilation spectroscopy to the investigation of zirconia-based nanomaterials doped with metal cations of different valence are reported. The slow-positron implantation spectroscopy combined with Doppler broadening measurements was employed to study the sintering of pressure-compacted nanopowders of tetragonal yttria-stabilised zirconia (t-YSZ) and t-YSZ with chromia additive. Positronium (Ps) formation in t-YSZ was proven by detecting 3γ-annihilations of ortho-Ps and was found to gradually decrease with increasing sintering temperature. A subsurface layer with enhanced 3γ-annihilations, compared to the deeper regions, could be identified. Addition of chromia was found to inhibit Ps formation. In addition, first results of positron lifetime measurements on nanopowders of zirconia phase-stabilised with MgO and CeO2 are presented.

Processing of Alumina-Toughened Zirconia Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Choi, Sung R.

2003-01-01

Dense and crack-free 10-mol%-yttria-stabilized zirconia (10YSZ)-alumina composites, containing 0 to 30 mol% of alumina, have been fabricated by hot pressing. Release of pressure before onset of cooling was crucial in obtaining crack-free material. Hot pressing at 1600 C resulted in the formation of ZrC by reaction of zirconia with grafoil. However, no such reaction was observed at 1500 C. Cubic zirconia and -alumina were the only phases detected from x-ray diffraction indicating no chemical reaction between the composite constituents during hot pressing. Microstructure of the composites was analyzed by scanning electron microscopy and transmission electron microscopy. Density and elastic modulus of the composites followed the rule-of-mixtures. Addition of alumina to 10YSZ resulted in lighter, stronger, and stiffer composites by decreasing density and increasing strength and elastic modulus.

Operation of Thin-Film Electrolyte Metal-Supported Solid Oxide Fuel Cells in Lightweight and Stationary Stacks: Material and Microstructural Aspects

PubMed Central

Roehrens, Daniel; Packbier, Ute; Fang, Qingping; Blum, Ludger; Sebold, Doris; Bram, Martin; Menzler, Norbert

2016-01-01

In this study we report on the development and operational data of a metal-supported solid oxide fuel cell with a thin film electrolyte under varying conditions. The metal-ceramic structure was developed for a mobile auxiliary power unit and offers power densities of 1 W/cm2 at 800 °C, as well as robustness under mechanical, thermal and chemical stresses. A dense and thin yttria-doped zirconia layer was applied to a nanoporous nickel/zirconia anode using a scalable adapted gas-flow sputter process, which allowed the homogeneous coating of areas up to 100 cm2. The cell performance is presented for single cells and for stack operation, both in lightweight and stationary stack designs. The results from short-term operation indicate that this cell technology may be a very suitable alternative for mobile applications. PMID:28773883

Gel polymer electrolytes based on nanofibrous polyacrylonitrile–acrylate for lithium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dul-Sun; Woo, Jang Chang; Youk, Ji Ho, E-mail: youk@inha.ac.kr

2014-10-15

Graphical abstract: - Highlights: • Nanofibrous polyacrylonitrile–acrylate membranes were prepared by electrospinning. • Trimethylolpropane triacrylate was used as a crosslinking agent of fibers. • The GPE based on PAN–acrylate (1/0.5) showed good electrochemical properties. - Abstract: Nanofibrous membranes for gel polymer electrolytes (GPEs) were prepared by electrospinning a mixture of polyacrylonitrile (PAN) and trimethylolpropane triacrylate (TMPTA) at weight ratios of 1/0.5 and 1/1. TMPTA is used to achieve crosslinking of fibers thereby improving mechanical strength. The average fiber diameters increased with increasing TMPTA concentration and the mechanical strength was also improved due to the enhanced crosslinking of fibers. GPEs basedmore » on electrospun membranes were prepared by soaking them in a liquid electrolyte of 1 M LiPF{sub 6} in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1, v/v). The electrolyte uptake and ionic conductivity of GPEs based on PAN and PAN–acrylate (weight ratio; 1/1 and 1/0.5) were investigated. Ionic conductivity of GPEs based on PAN–acrylate was the highest for PAN/acrylate (1/0.5) due to the proper swelling of fibers and good affinity with liquid electrolyte. Both GPEs based on PAN and PAN–acrylate membranes show good oxidation stability, >5.0 V vs. Li/Li{sup +}. Cells with GPEs based on PAN–acrylate (1/0.5) showed remarkable cycle performance with high initial discharge capacity and low capacity fading.« less

The effect of plasma on shear bond strength between resin cement and colored zirconia

PubMed Central

2017-01-01

PURPOSE To investigate the effect of non-thermal atmospheric pressure plasma (NTAPP) treatment on shear bond strength (SBS) between resin cement and colored zirconia made with metal chlorides. MATERIALS AND METHODS 60 zirconia specimens were divided into 3 groups using coloring liquid. Each group was divided again into 2 sub-groups using plasma treatment; the experimental group was treated with plasma, and the control group was untreated. The sub-groups were: N (non-colored), C (0.1 wt% aqueous chromium chloride solution), M (0.1 wt% aqueous molybdenum chloride solution), NP (non-colored with plasma), CP (0.1 wt% aqueous chromium chloride solution with plasma), and MP (0.1 wt% aqueous molybdenum chloride solution with plasma). Composite resin cylinders were bonded to zirconia specimens with MDP-based resin cement, and SBS was measured using a universal testing machine. All data was analyzed statistically using a 2-way ANOVA test and a Tukey test. RESULTS SBS significantly increased when specimens were treated with NTAPP regardless of coloring (P<.001). Colored zirconia containing molybdenum showed the highest value of SBS, regardless of NTAPP. The molybdenum group showed the highest SBS, whereas the chromium group showed the lowest. CONCLUSION NTAPP may increase the SBS of colored zirconia and resin cement. The NTAPP effect on SBS is not influenced by the presence of zirconia coloring. PMID:28435621

Translucency of Zirconia Ceramics before and after Artificial Aging.

PubMed

Walczak, Katarzyna; Meißner, Heike; Range, Ursula; Sakkas, Andreas; Boening, Klaus; Wieckiewicz, Mieszko; Konstantinidis, Ioannis

2018-03-11

The aging of zirconia ceramics (Y-TZP) is associated with tetragonal to monoclinic phase transformation. This change in microstructure may affect the optical properties of the ceramic. This study examines the effect of aging on the translucency of different zirconia materials. 120 disc-shaped specimens were fabricated from four zirconia materials: Cercon ht white, BruxZir Solid Zirconia, Zenostar T0, Lava Plus (n = 30 per group). Accelerated aging was performed in a steam autoclave (134°C, 0.2 MPa, 5 hours). CIELab coordinates (L*, a*, b*) and luminous reflectance (Y) were measured with a spectrophotometer before and after aging. Contrast ratio (CR) and translucency parameter (TP) were calculated from the L*, a*, b*, and Y tristimulus values. The general linear model (Bonferroni adjusted) was used to compare both parameters before and after aging, as well as between the different zirconia materials (p ≤ 0.05). CR and TP differed significantly before and after aging in all groups tested. Before aging, Zenostar T showed the highest and Lava Plus showed the lowest translucency. After aging, Cercon ht and Zenostar T showed the highest and BruxZir and Lava Plus the lowest translucency. Aging reduced the translucency in all specimens tested. Furthermore, translucency differed between the zirconia brands tested. Nevertheless, the differences were below the detectability threshold of the human eye. The aging process can influence the translucency and thus the esthetic outcome of zirconia restorations; however, the changes in translucency were minimal and probably undetectable by the human eye. © 2018 by the American College of Prosthodontists.

Hot Corrosion of Yttrium Stabilized Zirconia Coatings Deposited by Air Plasma Spray on a Nickel-Based Superalloy

NASA Astrophysics Data System (ADS)

Vallejo, N. Diaz; Sanchez, O.; Caicedo, J. C.; Aperador, W.; Zambrano, G.

In this research, the electrochemical impedance spectroscopy (EIS) and Tafel analysis were utilized to study the hot corrosion performance at 700∘C of air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) coatings with a NiCrAlY bond coat grown by high velocity oxygen fuel spraying (HVOF), deposited on an INCONEL 625 substrate, in contact with corrosive solids salts as vanadium pentoxide V2O5 and sodium sulfate Na2SO4. The EIS data were interpreted based on proposed equivalent electrical circuits using a suitable fitting procedure performed with Echem AnalystTM Software. Phase transformations and microstructural development were examined using X-ray diffraction (XRD), with Rietveld refinement for quantitative phase analysis, scanning electron microscopy (SEM) was used to determinate the coating morphology and corrosion products. The XRD analysis indicated that the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation from tetragonal to monoclinic zirconia phase.

Selective catalytic reduction system and process using a pre-sulfated zirconia binder

DOEpatents

Sobolevskiy, Anatoly; Rossin, Joseph A.

2010-06-29

A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO.sub.2)SO.sub.4, palladium, and a pre-sulfated zirconia binder. The inclusion of a pre-sulfated zirconia binder substantially increases the durability of a Pd-based SCR catalyst system. A system for implementing the disclosed process is further provided.

Correlative tomography at the cathode/electrolyte interfaces of solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Wankmüller, Florian; Szász, Julian; Joos, Jochen; Wilde, Virginia; Störmer, Heike; Gerthsen, Dagmar; Ivers-Tiffée, Ellen

2017-08-01

This paper introduces a correlative tomography technique. It visualizes the spatial organization of primary and secondary phases at the interface of La0.58Sr0.4Co0.2Fe0.8O3-δ cathode/10 mol% Gadolinia doped Ceria/8 mol% Yttria stabilized Zirconia electrolyte. It uses focused ion beam/scanning electron microscope tomography (FIB/SEM), and combines data sets from Everhart-Thornley and Inlens detector differentiating four primary and two secondary material phases. In addition, grayscale information is correlated to elemental distribution gained by energy dispersive X-ray spectroscopy in a scanning transmission electron microscope. Interdiffusion of GDC into YSZ and SrZrO3 as secondary phases depend (in both amount and spatial organization) on the varied co-sintering temperature of the GDC/YSZ electrolyte. The ion-blocking SrZrO3 forms a continuous layer on top of the temperature-dependent GDC/YSZ interdiffusion zone (ID) at and below a co-sintering temperature of 1200 °C; above it becomes intermittent. 2D FIB/SEM images of primary and secondary phases at 1100, 1200, 1300 and 1400 °C were combined with a 3D FIB/SEM reconstruction (1300 °C). This reveals that ;preferred; oxygen ion transport pathways from the LSCF cathode through GDC and the ID into the YSZ electrolyte only exist in samples sintered above 1200 °C. The applied correlative technique expands our understanding of this multiphase cathode/electrolyte interface region.

Electrolyte formulations

DOEpatents

Zhu, Ye; Strand, Deidre; Cheng, Gang

2018-05-29

An electrochemical cell including a silicon-based anode and an electrolyte, where the electrolyte is formulated to contain solvents having cyclic sulfone or cyclic sulfite chemical structure. Specific additional solvent and salt combinations yield superior performance in these electrochemical cells.

Air breathing lithium power cells

DOEpatents

Farmer, Joseph C.

2014-07-15

A cell suitable for use in a battery according to one embodiment includes a catalytic oxygen cathode; a stabilized zirconia electrolyte for selective oxygen anion transport; a molten salt electrolyte; and a lithium-based anode. A cell suitable for use in a battery according to another embodiment includes a catalytic oxygen cathode; an electrolyte; a membrane selective to molecular oxygen; and a lithium-based anode.

Electronic Structure at Electrode/Electrolyte Interfaces in Magnesium based Batteries

NASA Astrophysics Data System (ADS)

Balachandran, Janakiraman; Siegel, Donald

2015-03-01

Magnesium is a promising multivalent element for use in next generation electrochemical energy storage systems. However, a wide range of challenges such as low coulombic efficiency, low/varying capacity and cyclability need to be resolved in order to realize Mg based batteries. Many of these issues can be related to interfacial phenomena between the Mg anode and common electrolytes. Ab-initio based computational models of these interfaces can provide insights on the interfacial interactions that can be difficult to probe experimentally. In this work we present ab-initio computations of common electrolyte solvents (THF, DME) in contact with two model electrode surfaces namely -- (i) an ``SEI-free'' electrode based on Mg metal and, (ii) a ``passivated'' electrode consisting of MgO. We perform GW calculations to predict the reorganization of the molecular orbitals (HOMO/LUMO) upon contact with the these surfaces and their alignment with respect to the Fermi energy of the electrodes. These computations are in turn compared with more efficient GGA (PBE) & Hybrid (HSE) functional calculations. The results obtained from these computations enable us to qualitatively describe the stability of these solvent molecules at electrode-electrolyte interfaces

Effect of cements on fracture resistance of monolithic zirconia crowns

PubMed Central

Nakamura, Keisuke; Mouhat, Mathieu; Nergård, John Magnus; Lægreid, Solveig Jenssen; Kanno, Taro; Milleding, Percy; Örtengren, Ulf

2016-01-01

Abstract Objectives The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a standard (ISO 9917-1:2004). Second, load-to-failure test was performed to analyze the crown fracture resistance. CAD/CAM-produced monolithic zirconia crowns with a minimal thickness of 0.5 mm were prepared and cemented to dies with each cement. The crown–die samples were loaded until fracture. Results The compressive strength of SRC, RC-D and RC-C was significantly higher than those of ZPC and GIC (p < 0.05). However, there was no significant difference in the fracture load of the crown between the groups. Conclusion The values achieved in the load-to-failure test suggest that monolithic zirconia crowns with a minimal thickness of 0.5 mm may have good resistance against fracture regardless of types of cements. PMID:27335900

Comparison of light transmittance in different thicknesses of zirconia under various light curing units

PubMed Central

Egilmez, Ferhan; Ergun, Gulfem

2012-01-01

PURPOSE The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (α=.05). RESULTS ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance (P<.001). CONCLUSION Greater thickness of zirconia results in lower light transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials. PMID:22737314

Development of PVA based micro-porous polymer electrolyte by a novel preferential polymer dissolution process

NASA Astrophysics Data System (ADS)

Subramania, A.; Kalyana Sundaram, N. T.; Sukumar, N.

A micro-porous polymer electrolyte based on PVA was obtained from PVA-PVC based polymer blend film by a novel preferential polymer dissolution technique. The ionic conductivity of micro-porous polymer electrolyte increases with increase in the removal of PVC content. Finally, the effect of variation of lithium salt concentration is studied for micro-porous polymer electrolyte of high ionic conductivity composition. The ionic conductivity of the micro-porous polymer electrolyte is measured in the temperature range of 301-351 K. It is observed that a 2 M LiClO 4 solution of micro-porous polymer electrolyte has high ionic conductivity of 1.5055 × 10 -3 S cm -1 at ambient temperature. Complexation and surface morphology of the micro-porous polymer electrolytes are studied by X-ray diffraction and SEM analysis. TG/DTA analysis informs that the micro-porous polymer electrolyte is thermally stable upto 277.9 °C. Chronoamperommetry and linear sweep voltammetry studies were made to find out lithium transference number and stability of micro-porous polymer electrolyte membrane, respectively. Cyclic voltammetry study was performed for carbon/micro-porous polymer electrolyte/LiMn 2O 4 cell to reveal the compatibility and electrochemical stability between electrode materials.

Dehydration and crystallization kinetics of zirconia-yttria gels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramanathan, S.; Muraleedharan, R.V.; Roy, S.K.

1995-02-01

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process.more » The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ``glow effect`` reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form.« less

Scandia-and-Yttria-Stabilized Zirconia for Thermal Barriers

NASA Technical Reports Server (NTRS)

Mess, Derek

2003-01-01

yttria in suitable proportions has shown promise of being a superior thermal- barrier coating (TBC) material, relative to zirconia stabilized with yttria only. More specifically, a range of compositions in the zirconia/scandia/yttria material system has been found to afford increased resistance to deleterious phase transformations at temperatures high enough to cause deterioration of yttria-stabilized zirconia. Yttria-stabilized zirconia TBCs have been applied to metallic substrates in gas turbine and jet engines to protect the substrates against high operating temperatures. These coatings have porous and microcracked structures, which can accommodate strains induced by thermal-expansion mismatch and thermal shock. The longevity of such a coating depends upon yttria as a stabilizing additive that helps to maintain the zirconia in an yttria-rich, socalled non-transformable tetragonal crystallographic phase, thus preventing transformation to the monoclinic phase with an associated deleterious volume change. However, at a temperature greater than about 1,200 C, there is sufficient atomic mobility that the equilibrium, transformable zirconia phase is formed. Upon subsequent cooling, this phase transforms to the monoclinic phase, with an associated volume change that adversely affects the integrity of the coating. Recently, scandia was identified as a stabilizer that could be used instead of, or in addition to, yttria. Of particular interest are scandia-and-yttria-stabilized zirconia (SYSZ) compositions of about 6 mole percent scandia and 1 mole percent yttria, which have been found to exhibit remarkable phase stability at a temperature of 1,400 C in simple aging tests. Unfortunately, scandia is expensive, so that the problem becomes one of determining whether there are compositions with smaller proportions of scandia that afford the required high-temperature stability. In an attempt to solve this problem, experiments were performed on specimens made with reduced

Impedance spectroscopy of reduced monoclinic zirconia.

PubMed

Eder, Dominik; Kramer, Reinhard

2006-10-14

Zirconia doped with low-valent cations (e.g. Y3+ or Ca2+) exhibits an exceptionally high ionic conductivity, making them ideal candidates for various electrochemical applications including solid oxide fuel cells (SOFC) and oxygen sensors. It is nevertheless important to study the undoped, monoclinic ZrO2 as a model system to construct a comprehensive picture of the electrical behaviour. In pure zirconia a residual number of anion vacancies remains because of contaminants in the material as well as the thermodynamic disorder equilibrium, but electronic conduction may also contribute to the observed conductivity. Reduction of zirconia in hydrogen leads to the adsorption of hydrogen and to the formation of oxygen vacancies, with their concentration affected by various parameters (e.g. reduction temperature and time, surface area, and water vapour pressure). However, there is still little known about the reactivities of defect species and their effect on the ionic and electronic conduction. Thus, we applied electrochemical impedance spectroscopy to investigate the electric performance of pure monoclinic zirconia with different surface areas in both oxidizing and reducing atmospheres. A novel equivalent circuit model including parallel ionic and electronic conduction has previously been developed for titania and is used herein to decouple the conduction processes. The concentration of defects and their formation energies were measured using volumetric oxygen titration and temperature programmed oxidation/desorption.

Three- to nine-year survival estimates and fracture mechanisms of zirconia- and alumina-based restorations using standardized criteria to distinguish the severity of ceramic fractures.

PubMed

Moráguez, Osvaldo D; Wiskott, H W Anselm; Scherrer, Susanne S

2015-12-01

The aims of this study were set as follows: 1. To provide verifiable criteria to categorize the ceramic fractures into non-critical (i.e., amenable to polishing) or critical (i.e., in need of replacement) 2. To establish the corresponding survival rates for alumina and zirconia restorations 3. To establish the mechanism of fracture using fractography Fifty-eight patients restored with 115 alumina-/zirconia-based crowns and 26 zirconia-based fixed dental prostheses (FDPs) were included. Ceramic fractures were classified into four types and further subclassified into "critical" or "non-critical." Kaplan-Meier survival estimates were calculated for "critical fractures only" and "all fractures." Intra-oral replicas were taken for fractographic analyses. Kaplan-Meier survival estimates for "critical fractures only" and "all fractures" were respectively: Alumina single crowns: 90.9 and 68.3 % after 9.5 years (mean 5.71 ± 2.6 years). Zirconia single crowns: 89.4 and 80.9 % after 6.3 years (mean 3.88 ± 1.2 years). Zirconia FDPs: 68.6 % (critical fractures) and 24.6 % (all fractures) after 7.2 and 4.6 years respectively (FDP mean observation time 3.02 ± 1.4 years). No core/framework fractures were detected. Survival estimates varied significantly depending on whether "all" fractures were considered as failures or only those deemed as "critical". For all restorations, fractographic analyses of failed veneering ceramics systematically demonstrated heavy occlusal wear at the failure origin. Therefore, the relief of local contact pressures on unsupported ceramic is recommended. Occlusal contacts on mesial or distal ridges should systematically be eliminated. A classification standard for ceramic fractures into four categories with subtypes "critical" and "non-critical" provides a differentiated view of the survival of ceramic restorations.

Fracture load of metal-ceramic, monolithic, and bi-layered zirconia-based posterior fixed dental prostheses after thermo-mechanical cycling.

PubMed

López-Suárez, Carlos; Castillo-Oyagüe, Raquel; Rodríguez-Alonso, Verónica; Lynch, Christopher D; Suárez-García, María-Jesús

2018-06-01

This study aims to evaluate the fracture load of differently fabricated 3-unit posterior fixed dental prostheses (FDPs) with an intermediate pontic. Fifty sets of two stainless-steel abutments were randomly assigned to five groups (n = 10 each) depending on the material and technique used for manufacturing the FDPs: (1) Metal-ceramic (MC, control); (2) Lava Zirconia (LZ, bi-layered); (3) Lava Plus (LM, monolithic); (4) VITA In-Ceram YZ (YZ, bi-layered); and (5) IPS e-max ZirCAD (ZZ, bi-layered). After being luted to the dies, all FDPs were submitted to thermo-mechanical cycling (120,000 masticatory cycles, 50 N; plus 774 thermal cycles of 5 °C/55 °C, dwell time: 30 s). Samples were then subjected to a three-point bending test until fracture in a universal testing machine (cross-head speed: 1 mm/min). Fracture load of the veneering ceramic (VF) and total fracture load (TF) were recorded. Microstructure and failure patterns were assessed. Data was analysed using one-way ANOVA and Tukey HSD post-hoc tests (α = 0.05). MC restorations recorded higher VF and TF values than did zirconia FDPs (p = 0.0001), which showed no between-group differences. Within the bi-layered groups, TF was significantly higher than VF. LM pieces registered lower average grain size than did LZ specimens (p = 0.001). Overall, the connector was the weakest part. All of the groups tested could withstand clinical chewing forces in terms of average fracture load. Zirconia-based samples performed similarly to each other, but showed lower mean fracture load values than did metal-ceramic ones. Monolithic zirconia may be recommendable for solving the chipping problem. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solid state oxygen sensor

DOEpatents

Garzon, Fernando H.; Chung, Brandon W.; Raistrick, Ian D.; Brosha, Eric L.

1996-01-01

Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer.

Solid state oxygen sensor

DOEpatents

Garzon, F.H.; Chung, B.W.; Raistrick, I.D.; Brosha, E.L.

1996-08-06

Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer. 4 figs.

A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

PubMed Central

Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

2016-01-01

A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system. PMID:26878890

Effect of fabrication parameters on coating properties of tubular solid oxide fuel cell electrolyte prepared by vacuum slurry coating

NASA Astrophysics Data System (ADS)

Son, Hui-Jeong; Song, Rak-Hyun; Lim, Tak-Hyoung; Lee, Seung-Bok; Kim, Sung-Hyun; Shin, Dong-Ryul

The process of vacuum slurry coating for the fabrication of a dense and thin electrolyte film on a porous anode tube is investigated for application in solid oxide fuel cells. 8 mol% yttria stabilized zirconia is coated on an anode tube by vacuum slurry-coating process as a function of pre-sintering temperature of the anode tube, vacuum pressure, slurry concentration, number of coats, and immersion time. A dense electrolyte layer is formed on the anode tube after final sintering at 1400 °C. With decrease in the pre-sintering temperature of the anode tube, the grain size of the coated electrolyte layer increases and the number of surface pores in the coating layer decreases. This is attributed to a reduced difference in the respective shrinkage of the anode tube and the electrolyte layer. The thickness of the coated electrolyte layer increases with the content of solid powder in the slurry, the number of dip-coats, and the immersion time. Although vacuum pressure has no great influence on the electrolyte thickness, higher vacuum produces a denser coating layer, as confirmed by low gas permeability and a reduced number of defects in the coating layer. A single cell with the vacuum slurry coated electrolyte shows a good performance of 620 mW cm -2 (0.7 V) at 750 °C. These experimental results indicate that the vacuum slurry-coating process is an effective method to fabricate a dense thin film on a porous anode support.

Wear properties of alumina/zirconia composite ceramics for joint prostheses measured with an end-face apparatus.

PubMed

Morita, Yusuke; Nakata, Kenichi; Kim, Yoon-Ho; Sekino, Tohru; Niihara, Koichi; Ikeuchi, Ken

2004-01-01

While only alumina is applied to all-ceramic joint prostheses at present, a stronger ceramic is required to prevent fracture and chipping due to impingement and stress concentration. Zirconia could be a potential substitute for alumina because it has high strength and fracture toughness. However, the wear of zirconia/zirconia combination is too high for clinical use. Although some investigations on composite ceramics revealed that mixing of different ceramics was able to improve the mechanical properties of ceramics, there are few reports about wear properties of composite ceramics for joint prosthesis. Since acetabular cup and femoral head of artificial hip joint are finished precisely, they indicate high geometric conformity. Therefore, wear test under flat contact was carried out with an end-face wear testing apparatus for four kinds of ceramics: alumina monolith, zirconia monolith, alumina-based composite ceramic, and zirconia based composite ceramic. Mean contact pressure was 10 MPa and sliding velocity was 40 mm/s. The wear test continued for 72 hours and total sliding distance was 10 km. After the test, the wear factor was calculated. Worn surfaces were observed with a scanning electron micrograph (SEM). The results of this wear test show that the wear factors of the both composite ceramics are similarly low and their mechanical properties are much better than those of the alumina monolith and the zirconia monolith. According to these results, it is predicted that joint prostheses of the composite ceramics are safer against break down and have longer lifetime compared with alumina/alumina joint prostheses.

Mechanical behavior of single-layer ceramized zirconia abutments for dental implant prosthetic rehabilitation

PubMed Central

Jiménez-Melendo, Manuel; Llena-Blasco, Oriol; Bruguera, August; Llena-Blasco, Jaime; Yáñez-Vico, Rosa-María; García-Calderón, Manuel; Vaquero-Aguilar, Cristina; Velázquez-Cayón, Rocío; Gutiérrez-Pérez, José-Luis

2014-01-01

Objectives: This study was undertaken to characterize the mechanical response of bare (as-received) and single-layer ceramized zirconia abutments with both internal and external connections that have been developed to enhanced aesthetic restorations. Material and Methods: Sixteen zirconia implant abutments (ZiReal Post®, Biomet 3i, USA) with internal and external connections have been analyzed. Half of the specimens were coated with a 0.5mm-thick layer of a low-fusing fluroapatite ceramic. Mechanical tests were carried out under static (constant cross-head speed of 1mm/min until fracture) and dynamic (between 100 and 400N at a frequency of 1Hz) loading conditions. The failure location was identified by electron microscopy. The removal torque of the retaining screws after testing was also evaluated. Results: The average fracture strength was above 300N for all the abutments, regardless of connection geometry and coating. In most of the cases (94%), failure occurred by abutment fracture. No significant differences were observed either in fatigue behavior and removal torque between the different abutment groups. Conclusions: Mechanical behavior of Zireal zirconia abutments is independent of the type of internal/external connection and the presence/absence of ceramic coating. This may be clinically valuable in dental rehabilitation to improve the aesthetic outcome of zirconia-based dental implant systems. Key words:Dental implant, zirconia, ceramic structure, mechanical properties. PMID:25674313

Use of Additives to Improve Performance of Methyl Butyrate-Based Lithium-Ion Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Bugga, Ratnakumar V.

2011-01-01

This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. To this end, a number of electrolyte formulations have been developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl butyrate-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalato)borate (LiBOB), which have been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. Improved performance has been demonstrated of Li-ion cells with methyl butyrate-based electrolytes, including 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %); 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 4% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + lithium oxalate; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% VC; and 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 0.10M LiBOB. These electrolytes have been shown to improve performance in MCMB-LiNiCoO2 and graphite-LiNi1/3Co1/3Mn1/3O2 experimental Li-ion cells. A number of LiPF6-based mixed carbonate electrolyte formulations have been developed that contain ester co-solvents, which have been optimized for operation at low temperature, while still providing reasonable performance at high temperature. For example, a number of ester co-solvents were investigated, including methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), and butyl butyrate (BB) in multi-component electrolytes of the following composition: 1.0M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (20:60:20 v/v %) [where X = ester co-solvent]. ["Optimized Car bon ate and Ester-Based Li-Ion Electrolytes", NASA Tech Briefs, Vol. 32, No. 4 (April 2008), p. 56.] Focusing upon improved rate

A Model-based Prognostics Methodology for Electrolytic Capacitors Based on Electrical Overstress Accelerated Aging

NASA Technical Reports Server (NTRS)

Celaya, Jose; Kulkarni, Chetan; Biswas, Gautam; Saha, Sankalita; Goebel, Kai

2011-01-01

A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated aging test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation progression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognostics methods typically used for remaining useful life predictions in other applications.

Multinuclear NMR study of silica fiberglass modified with zirconia.

PubMed

Lapina, O B; Khabibulin, D F; Terskikh, V V

2011-01-01

Silica fiberglass textiles are emerging as uniquely suited supports in catalysis, which offer unprecedented flexibility in designing advanced catalytic systems for chemical and auto industries. During manufacturing fiberglass materials are often modified with additives of various nature to improve glass properties. Glass network formers, such as zirconia and alumina, are known to provide the glass fibers with higher strength and to slow down undesirable devitrification processes. In this work multinuclear (1)H, (23)Na, (29)Si, and (91)Zr NMR spectroscopy was used to characterize the effect of zirconia on the molecular-level fiberglass structure. (29)Si NMR results help in understanding why zirconia-modified fiberglass is more stable towards devitrification comparing with pure silica glass. Internal void spaces formed in zirconia-silica glass fibers after acidic leaching correlate with sodium and water distributions in the starting bulk glass as probed by (23)Na and (1)H NMR. These voids spaces are important for stabilization of catalytically active species in the supported catalysts. Potentials of high-field (91)Zr NMR spectroscopy to study zirconia-containing glasses and similarly disordered systems are illustrated. Copyright © 2011 Elsevier Inc. All rights reserved.

High-temperature zirconia insulation and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.; Lewis, J. Jr.

The present invention is directed to a highly pure, partially stabilized, fibrous zirconia composite for use as thermal insulation in environments where temperatures up to about 2,000/sup 0/C are utilized. The composite of the present invention is fabricated into any suitable configuration such as a cone, cylinder dome or the like by vacuum molding an aqueous slurry of partially stabilized zirconia fibers into a desired configuration on a suitably shaped mandrel. The molded fibers are infiltrated with zirconyl nitrate and the resulting structure is then dried to form a rigid structure which may be removed and placed in a furnace. The structure is then heated in air to a temperature of about 600/sup 0/C for driving off the nitrate from the structure and for oxidizing the zirconyl ion to zirconia. Thereafter, the structure is heated to about 950/sup 0/ to 1,250/sup 0/C to fuse the zirconia fibers at their nexi in a matrix of zirconia. The composite produced by the present invention is self-supporting and can be readily machined to desired final dimensions. Additional heating to about 1800/sup 0/ to 2000/sup 0/C further improves structural rigidity.

High-temperature zirconia insulation and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.; Lewis, J. Jr.

1988-05-10

The present invention is directed to a highly pure, partially stabilized, fibrous zirconia composite for use as thermal insulation in environments where temperatures up to about 2,000 C are utilized. The composite of the present invention is fabricated into any suitable configuration such as a cone, cylinder, dome or the like by vacuum molding an aqueous slurry of partially stabilized zirconia fibers into a desired configuration on a suitably shaped mandrel. The molded fibers are infiltrated with zirconyl nitrate and the resulting structure is then dried to form a rigid structure which may be removed and placed in a furnace. The structure is then heated in air to a temperature of about 600 C for driving off the nitrate from the structure and for oxidizing the zirconyl ion to zirconia. Thereafter, the structure is heated to about 950 to 1,250 C to fuse the zirconia fibers at their nexi in a matrix of zirconia. The composite produced by the present invention is self-supporting and can be readily machined to desired final dimensions. Additional heating to about 1,800 to 2,000 C further improves structural rigidity.

High-temperature zirconia insulation and method for making same

DOEpatents

Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.; Lewis, Jr., John

1988-01-01

The present invention is directed to a highly pure, partially stabilized, fibrous zirconia composite for use as thermal insulation in environments where temperatures up to about 2000.degree. C. are utilized. The composite of the present invention is fabricated into any suitable configuration such as a cone, cylinder, dome or the like by vacuum molding an aqueous slurry of partially stabilized zirconia fibers into a desired configuration on a suitably shaped mandrel. The molded fibers are infiltrated with zirconyl nitrate and the resulting structure is then dried to form a rigid structure which may be removed and placed in a furnace. The structure is then heated in air to a temperature of about 600.degree. C. for driving off the nitrate from the structure and for oxidizing the zirconyl ion to zirconia. Thereafter, the structure is heated to about 950.degree. to 1,250.degree. C. to fuse the zirconia fibers at their nexi in a matrix of zirconia. The composite produced by the present invention is self-supporting and can be readily machined to desired final dimensions. Additional heating to about 1800.degree. to 2000.degree. C. further improves structural rigidity.

Novel choline-based ionic liquids as safe electrolytes for high-voltage lithium-ion batteries

NASA Astrophysics Data System (ADS)

Yong, Tianqiao; Zhang, Lingzhi; Wang, Jinglun; Mai, Yongjin; Yan, Xiaodan; Zhao, Xinyue

2016-10-01

Three choline-based ionic liquids functionalized with trimethylsilyl, allyl, and cynoethyl groups are synthesized in an inexpensive route as safe electrolytes for high-voltage lithium-ion batteries. The thermal stabilities, viscosities, conductivities, and electrochemical windows of these ILs are reported. Hybrid electrolytes were formulated by doping with 0.6 M LiPF6/0.4 M lithium oxalydifluoroborate (LiODFB) as salts and dimethyl carbonate (DMC) as co-solvent. By using 0.6 M LiPF6/0.4 M LiODFB trimethylsilylated choline-based IL (SN1IL-TFSI)/DMC as electrolyte, LiCoO2/graphite full cell showed excellent cycling performance with a capacity of 152 mAh g-1 and 99% capacity retention over 90 cycles at a cut-off voltage of 4.4 V. The propagation rate of SN1IL-TFSI)/DMC electrolyte is only one quarter of the commercial electrolyte (1 M LiPF6 EC/DEC/DMC, v/v/v = 1/1/1), suggesting a better safety feature.

An experimental study on PEO polymer electrolyte based all-solid-state supercapacitor

NASA Astrophysics Data System (ADS)

Yijing, Yin

Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I 2 mediator was added to improve the conductivity of PEO electrolyte and

Solid oxide fuel cell operable over wide temperature range

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

2001-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Interfacial material for solid oxide fuel cell

DOEpatents

Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

1999-01-01

Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

Twenty-nine-month follow-up of a paediatric zirconia dental crown.

PubMed

Lopez Cazaux, Serena; Hyon, Isabelle; Prud'homme, Tony; Dajean Trutaud, Sylvie

2017-06-14

The aim of this paper is to present the long-term follow-up of one paediatric zirconia crown on a deciduous molar. Preformed crowns are part of the armamentarium in paediatric dentistry. In recent years, aesthetic alternatives to preformed metal crowns have been developed, first preveneered crowns and then zirconia crowns. This paper describes the restoration of a primary molar with a zirconia crown (EZ-Pedo, Loomis, California, USA) in an 8-year-old boy. In this clinical case, the protocol for the implementation and maintenance of zirconia crowns is detailed. The patient was followed up for 29 months until the natural exfoliation of his primary molar. The adaptation of the zirconia crown, the gingival health and the wear on the opposing tooth were considered. In this case, the paediatric zirconia crown allowed sustainable functional restoration while restoring a natural appearance of the tooth. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Influence of cement thickness on resin-zirconia microtensile bond strength

PubMed Central

Lee, Tae-Hoon; Ahn, Jin-Soo; Shim, June-Sung; Han, Chong-Hyun

2011-01-01

PURPOSE The aim of this study was to evaluate the influence of resin cement thickness on the microtensile bond strength between zirconium-oxide ceramic and resin cement. MATERIALS AND METHODS Thirty-two freshly extracted molars were transversely sectioned at the deep dentin level and bonded to air-abraded zirconium oxide ceramic disks. The specimens were divided into 8 groups based on the experimental conditions (cement type: Rely X UniCem or Panavia F 2.0, cement thickness: 40 or 160 µm, storage: thermocycled or not). They were cut into microbeams and stored in 37℃ distilled water for 24 h. Microbeams of non-thermocycled specimens were submitted to a microtensile test, whereas those of thermocycled groups were thermally cycled for 18,000 times immediately before the microtensile test. Three-way ANOVA and Sheffe's post hoc tests were used for statistical analysis (α=95%). RESULTS All failures occurred at the resin-zirconia interface. Thermocycled groups showed lower microtensile bond strength than non-thermocycled groups (P<.001). Differences in cement thickness did not influence the resin-zirconia microtensile bond strength given the same resin cement or storage conditions (P>.05). The number of adhesive failures increased after thermocycling in all experimental conditions. No cohesive failure was observed in any experimental group. CONCLUSION When resin cements of adhesive monomers are applied over air-abraded zirconia restorations, the degree of fit does not influence the resin-zirconia microtensile bond strength. PMID:22053241

Conductivity studies of PEG based polymer electrolyte for applications as electrolyte in ion batteries

NASA Astrophysics Data System (ADS)

Patil, Ravikumar V.; Praveen, D.; Damle, R.

2018-05-01

Development of lithium ion batteries employing solid polymer electrolytes as electrolyte material has led to efficient energy storage and usage in many portable devices. However, due to a few drawbacks like lower ionic conductivity of solid polymer electrolytes (SPEs), studies on SPEs for improvement in conductivity still have a good scope. In the present paper, we report the conductivity studies of a new SPE with low molecular weight poly ethylene glycol (PEG) as host polymer in which a salt with larger anion Lithium trifluro methane sulphonate (LTMS). XRD studies have revealed that the salt completely dissociates in the polymer giving a good stable electrolyte at lower salt concentration. Conductivity of the SPEs has been studied as a function of temperature and we reiterate that the conductivity is a thermally activated process and follows Arrhenius type behavior.

Solid-state supercapacitors with ionic liquid based gel polymer electrolyte: Effect of lithium salt addition

NASA Astrophysics Data System (ADS)

Pandey, G. P.; Hashmi, S. A.

2013-12-01

Performance characteristics of the solid-state supercapacitors fabricated with ionic liquid (IL) incorporated gel polymer electrolyte and acid treated multiwalled carbon nanotube (MWCNT) electrodes have been studied. The effect of Li-salt (LiPF6) addition in the IL (1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate, EMImFAP) based gel electrolyte on the performance of supercapacitors has been specifically investigated. The LiPF6/IL/poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) gel electrolyte film possesses excellent electrochemical window of 4 V (from -2.0 to 2.0 V), high ionic conductivity ∼2.6 × 10-3 S cm-1 at 20 °C and high enough thermal stability. The comparative performance of supercapacitors employing electrolytes with and without lithium salt has been evaluated by impedance spectroscopy and cyclic voltammetric studies. The acid-treated MWCNT electrodes show specific capacitance of ∼127 F g-1 with IL/LiPF6 containing gel polymer electrolyte as compared to that with the gel polymer electrolyte without Li-salt, showing the value of ∼76 F g-1. The long cycling stability of the solid state supercapacitor based on the Li-salt containing gel polymer electrolyte confirms the electrochemical stability of the electrolyte.

Single Crystal Growth of Zirconia Utilizing a Skull Melting Technique,

DTIC Science & Technology

1979-08-01

23 REFERENCES 24 Illustrations 1. Cutaway View of Skull Crucible 11 2. Section View of Skull Crucible 11 3. Stabilized Zirconia Powder Being Added to...E. R., (1968) J. Cryst. Growth, 2:243. 11 ... . . l l&I. .. . .:. . . N ’ - . . . . . . i . . . . . . . . .: P Figure 3. Stabilized Zirconia Powder Figure...colorless. The zirconia powder used in these experiments was obtained from N. L. Industries, Inc. Samples of the powder with 25 weight percent Y 2 0 3

Effect of nanoparticles dispersion on viscoelastic properties of epoxy–zirconia polymer nanocomposites

NASA Astrophysics Data System (ADS)

Singh, Sushil Kumar; Kumar, Abhishek; Jain, Anuj

2018-03-01

In the present work zirconia-nanoparticles were dispersed in epoxy matrix to form epoxy-zirconia polymer nanocomposites using ultrasonication and viscoelastic properties of nanocomposites were investigated. For the same spherical zirconia-nanoparticles (45 nm) were dispersed in weight fraction of 2, 4, 6 and 8 % to reinforce the epoxy. DMA results show the significant enhancement in viscoelastic properties with the dispersion of zirconia nanoparticles in the epoxy matrix. The value of storage modulus and glass transition temperature increases from 179 MPa (pristine) to 225 MPa (6 wt.% ZrO2) and 61 °C (pristine) to 70 °C (6 wt.% ZrO2) respectively with the dispersion of zirconia nanoparticles in the epoxy.

Effect of nanoparticles dispersion on viscoelastic properties of epoxy-zirconia polymer nanocomposites

NASA Astrophysics Data System (ADS)

Singh, Sushil Kumar; Kumar, Abhishek; Jain, Anuj

2018-03-01

In the present work zirconia-nanoparticles were dispersed in epoxy matrix to form epoxy-zirconia polymer nanocomposites using ultrasonication and viscoelastic properties of nanocomposites were investigated. For the same spherical zirconia-nanoparticles (45 nm) were dispersed in weight fraction of 2, 4, 6 and 8 % to reinforce the epoxy. DMA results show the significant enhancement in viscoelastic properties with the dispersion of zirconia nanoparticles in the epoxy matrix. The value of storage modulus and glass transition temperature increases from 179 MPa (pristine) to 225 MPa (6 wt.% ZrO2) and 61 °C (pristine) to 70 °C (6 wt.% ZrO2) respectively with the dispersion of zirconia nanoparticles in the epoxy.

Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing.

PubMed

Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

2014-12-01

The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.

Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing

PubMed Central

Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

2014-01-01

The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces. PMID:25059249

Organosilicon-Based Electrolytes for Long-Life Lithium Primary Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenton, Kyle R.; Nagasubramanian, Ganesan; Staiger, Chad L.

2015-09-01

This report describes advances in electrolytes for lithium primary battery systems. Electrolytes were synthesized that utilize organosilane materials that include anion binding agent functionality. Numerous materials were synthesized and tested in lithium carbon monofluoride battery systems for conductivity, impedance, and capacity. Resulting electrolytes were shown to be completely non-flammable and showed promise as co-solvents for electrolyte systems, due to low dielectric strength.

Bond Strength of Resin Cements to Zirconia Ceramic Using Adhesive Primers.

PubMed

Stefani, Ariovaldo; Brito, Rui Barbosa; Kina, Sidney; Andrade, Oswaldo Scopin; Ambrosano, Gláucia Maria Bovi; Carvalho, Andreia Assis; Giannini, Marcelo

2016-07-01

To evaluate the influence of adhesive primers on the microshear bond strength of resin cements to zirconia ceramic. Fifty zirconia plates (12 mm × 5 mm × 1.5 mm thick) of a commercially available zirconium oxide ceramic (ZirCad) were sintered, sandblasted with aluminum oxide particles, and cleaned ultrasonically before bonding. The plates were randomly divided into five groups of 10. Three resin cements were selected (RelyX ARC, Multilink Automix, Clearfil SA Cement self-adhesive resin cement), along with two primers (Metal-Zirconia Primer, Alloy Primer) and one control group. The primers and resin cements were used according to manufacturers' recommendations. The control group comprised the conventional resin cement (RelyX ARC) without adhesive primer. Test cylinders (0.75 mm diameter × 1 mm high) were formed on zirconia surfaces by filling cylindrical Tygon tube molds with resin cement. The specimens were stored in distilled water for 24 hours at 37°C, then tested for shear strength on a Shimadzu EZ Test testing machine at 0.5 mm/min. Bond strength data were analyzed statistically by two-way ANOVA and Dunnett's test (5%). The bond strength means in MPa (± s.d.) were: RelyX ARC: 28.1 (6.6); Multilink Automix: 37.6 (4.5); Multilink Automix + Metal-Zirconia Primer: 55.7 (4.0); Clearfil SA Cement: 46.2 (3.3); and Clearfil SA Cement + Alloy Primer: 47.0 (4.1). Metal-Zirconia Primer increased the bond strength of Multilink Automix resin cement to zirconia, but no effect was observed for Alloy Primer using Clearfil SA Cement. RelyX ARC showed the lowest bond strength to zirconia. © 2015 by the American College of Prosthodontists.

Retention Forces between Titanium and Zirconia Components of Two-Part Implant Abutments with Different Techniques of Surface Modification.

PubMed

von Maltzahn, Nadine Freifrau; Holstermann, Jan; Kohorst, Philipp

2016-08-01

The adhesive connection between titanium base and zirconia coping of two-part abutments may be responsible for the failure rate. A high mechanical stability between both components is essential for the long-term success. The aim of the present in-vitro study was to evaluate the influence of different surface modification techniques and resin-based luting agents on the retention forces between titanium and zirconia components in two-part implant abutments. A total of 120 abutments with a titanium base bonded to a zirconia coping were investigated. Two different resin-based luting agents (Panavia F 2.0 and RelyX Unicem) and six different surface modifications were used to fix these components, resulting in 12 test groups (n = 10). The surface of the test specimens was mechanically pretreated with aluminium oxide blasting in combination with application of two surface activating primers (Alloy Primer, Clearfil Ceramic Primer) or a tribological conditioning (Rocatec), respectively. All specimens underwent 10,000 thermal cycles between 5°C and 55°C in a moist environment. A pull-off test was then conducted to determine retention forces between the titanium and zirconia components, and statistical analysis was performed (two-way anova). Finally, fracture surfaces were analyzed by light and scanning electron microscopy. No significant differences were found between Panavia F 2.0 and RelyX Unicem. However, the retention forces were significantly influenced by the surface modification technique used (p < 0.001). For both luting agents, the highest retention forces were found when adhesion surfaces of both the titanium bases and the zirconia copings were pretreated with aluminium oxide blasting, and with the application of Clearfil Ceramic Primer. Surface modification techniques crucially influence the retention forces between titanium and zirconia components in two-part implant abutments. All adhesion surfaces should be pretreated by sandblasting. Moreover, a

Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

NASA Astrophysics Data System (ADS)

Sherly, K. B.; Rakesh, K.

2014-01-01

Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl2ṡ8H2O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherly, K. B.; Rakesh, K.

Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}⋅8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with themore » theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.« less

Processing and Mechanical Properties of Various Zirconia/Alumina Composites for Fuel Cell Applications

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Bansal, Narottam P.

2002-01-01

Various electrolyte materials for solid oxide fuel cells were fabricated by hot pressing 10 mol% yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina, particulates and platelets, each containing 0 to 30 mol% alumina. Flexure strength and fracture toughness of both particulate and platelet composites at ambient temperature increased with increasing alumina content, reaching a maximum at 30 mot% alumina. For a given alumina content, strength of particulate composites was greater than that of platelet composites, whereas, the difference in fracture toughness between the two composite systems was negligible. No virtual difference in elastic modulus and density was observed for a given alumina content between particulate and platelet composites. Thermal cycling up to 10 cycles between 200 to 1000 C did not show any effect on strength degradation of the 30 mol% platelet composites, indicative of negligible influence of CTE mismatches between YSZ matrix and alumina grains.

3D-characterization of the veneer-zirconia interface using FIB nano-tomography.

PubMed

Mainjot, Amélie K; Douillard, Thierry; Gremillard, Laurent; Sadoun, Michaël J; Chevalier, Jérôme

2013-02-01

The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a challenge. However this interface has been reported to act on residual stress in the veneering ceramic, which plays a significant role in clinical failures such as chipping. The objective of this study was thus to investigate the veneer-zirconia interface using a recent 3D-analysis tool and to confront these observations to residual stress measurements in the veneering ceramic. Two cross-sectioned bilayered disc samples (veneer on zirconia), exhibiting different residual stress profiles in the veneering ceramic, were investigated using 2D and 3D imaging (respectively Scanning Electron Microscopy (SEM) and Focused Ion Beam nanotomography (FIB-nt), associated with chemical analysis by Energy Dispersive X-ray Spectroscopy (EDS). The observations did not reveal any structural change in the bulk of zirconia layer of both samples. However the presence of structural alterations and sub-surface microcracks were highlighted in the first micrometer of zirconia surface, exclusively for the sample exhibiting interior tensile stress in the veneering ceramic. No interdiffusion phenomena were observed. FIB nanotomography was proven to be a powerful technique to study the veneer-zirconia interface. The determination of the origin and the nature of zirconia alterations need to be further studied. The results of the present study support the hypothesis that zirconia surface property changes could be involved in the development of tensile stress in the veneering ceramic, increasing the risk of chipping. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Surface crystalline phases and nanoindentation hardness of explanted zirconia femoral heads.

PubMed

Catledge, Shane A; Cook, Monique; Vohra, Yogesh K; Santos, Erick M; McClenny, Michelle D; David Moore, K

2003-10-01

One new and nine explanted zirconia femoral heads were studied using glancing angle X-ray diffraction, scanning electron microscopy, and nanoindentation hardness techniques. All starting zirconia implants consisted only of tetragonal zirconia polycrystals (TZP). For comparison, one explanted alumina femoral head was also studied. Evidence for a surface tetragonal-to-monoclinic zirconia phase transformation was observed in some implants, the extent of which was varied for different in-service conditions. A strong correlation was found between increasing transformation to the monoclinic phase and decreasing surface hardness. Microscopic investigations of some of the explanted femoral heads revealed ultra high molecular weight polyethylene and metallic transfer wear debris.

A study of alternative methods for reclaiming oxygen from carbon dioxide and water by a solid-electrolyte process for spacecraft applications

NASA Technical Reports Server (NTRS)

1971-01-01

Two alternative technical approaches were studied for application of an electrochemical process using a solid oxide electrolyte (zirconia stabilized by yttria or scandia) to oxygen reclamation from carbon dioxide and water, for spacecraft life support systems. Among the topics considered are the advisability of proceeding to engineering prototype development and fabrication of a full scale model for the system concept, the optimum choice of method or approach to be carried into prototype development, and the technical problem areas which exist.

Fracture resistance and failure mode of posterior fixed dental prostheses fabricated with two zirconia CAD/CAM systems

PubMed Central

López-Suárez, Carlos; Gonzalo, Esther; Peláez, Jesús; Rodríguez, Verónica

2015-01-01

Background In recent years there has been an improvement of zirconia ceramic materials to replace posterior missing teeth. To date little in vitro studies has been carried out on the fracture resistance of zirconia veneered posterior fixed dental prostheses. This study investigated the fracture resistance and the failure mode of 3-unit zirconia-based posterior fixed dental prostheses fabricated with two CAD/CAM systems. Material and Methods Twenty posterior fixed dental prostheses were studied. Samples were randomly divided into two groups (n=10 each) according to the zirconia ceramic analyzed: Lava and Procera. Specimens were loaded until fracture under static load. Data were analyzed using Wilcoxon´s rank sum test and Wilcoxon´s signed-rank test (P<0.05). Results Partial fracture of the veneering porcelain occurred in 100% of the samples. Within each group, significant differences were shown between the veneering and the framework fracture resistance (P=0.002). The failure occurred in the connector cervical area in 80% of the cases. Conclusions All fracture load values of the zirconia frameworks could be considered clinically acceptable. The connector area is the weak point of the restorations. Key words:Fixed dental prostheses, zirconium-dioxide, zirconia, fracture resistance, failure mode. PMID:26155341

Optical properties and light irradiance of monolithic zirconia at variable thicknesses.

PubMed

Sulaiman, Taiseer A; Abdulmajeed, Aous A; Donovan, Terrence E; Ritter, André V; Vallittu, Pekka K; Närhi, Timo O; Lassila, Lippo V

2015-10-01

The aims of this study were to: (1) estimate the effect of polishing on the surface gloss of monolithic zirconia, (2) measure and compare the translucency of monolithic zirconia at variable thicknesses, and (3) determine the effect of zirconia thickness on irradiance and total irradiant energy. Four monolithic partially stabilized zirconia (PSZ) brands; Prettau® (PRT, Zirkonzahn), Bruxzir® (BRX, Glidewell), Zenostar® (ZEN, Wieland), Katana® (KAT, Noritake), and one fully stabilized zirconia (FSZ); Prettau Anterior® (PRTA, Zirkonzahn) were used to fabricate specimens (n=5/subgroup) with different thicknesses (0.5, 0.7, 1.0, 1.2, 1.5, and 2.0mm). Zirconia core material ICE® Zircon (ICE, Zirkonzahn) was used as a control. Surface gloss and translucency were evaluated using a reflection spectrophotometer. Irradiance and total irradiant energy transmitted through each specimen was quantified using MARC® Resin Calibrator. All specimens were then subjected to a standardized polishing method and the surface gloss, translucency, irradiance, and total irradiant energy measurements were repeated. Statistical analysis was performed using two-way ANOVA and post-hoc Tukey's tests (p<0.05). Surface gloss was significantly affected by polishing (p<0.05), regardless of brand and thickness. Translucency values ranged from 5.65 to 20.40 before polishing and 5.10 to 19.95 after polishing. The ranking from least to highest translucent (after polish) was: BRX=ICE=PRTzirconia and the amount was brand dependent (p<0.05). Brand selection, thickness, and polishing of monolithic zirconia can affect the ultimate clinical outcome of the optical properties of zirconia restorations. FSZ is relatively more polishable and translucent than PSZ. Copyright © 2015 Academy of Dental

Influence of cleaning methods on resin bonding to saliva-contaminated zirconia.

PubMed

Yoshida, Keiichi

2018-02-08

The aim of this study was to investigate the influence of different cleaning methods on the shear bond strengths of 2 resin cements to saliva-contaminated zirconia. After saliva contamination, alumina-blasted zirconia specimens were cleaned with 1 of 5 methods of water-rinsing (SA), K-etchant GEL phosphoric acid (PA), Ivoclean (IC), AD Gel (ADG), or additional alumina-blasting (AB). Alumina-blasted zirconia without saliva contamination was used as control group (Cont). Composite cylinders were bonded to the zirconia with 1 of 2 dual-cured resin cements. The bond strengths were measured by shear testing after 24 hours (TC0) and after thermal cycling at 4°C-60°C (TC10 000) and specimen surfaces were evaluated using X-ray photoelectron spectroscopy (XPS). Data were statistically analyzed using 3-way analysis of variance and Tukey test (α = 0.05). There were no significant differences in the bond strengths of 2 resin cements between the Cont ADG, and AB groups before and after TCs (P > .05). SA, PA, and IC groups did not exhibit durable resin bonding to zirconia. XPS showed that carbon and nitrogen increased in the SA group in comparison to the Cont group. The concentration of carbon in other 4 groups returned to the concentration range of the Cont group; however, nitrogen was not detected in the only AB group. Saliva contamination significantly reduced the bond strength of 2 resin cements to zirconia. Additional AB or cleaning with ADG resulted in effective cleaning of saliva contamination and preserved resin cement bond strength to zirconia. Saliva contamination occurs during clinical procedures for adjustment of zirconia ceramic restorations in the oral environment. AD Gel application is effective for removing saliva contaminants on the alumina-blasted zirconia surface beforehand by the dental laboratory instead of additional AB since AD Gel application and AB had a similar effect on the removal of organic components of saliva. © 2018 Wiley Periodicals

Fracture of Reduced-Diameter Zirconia Dental Implants Following Repeated Insertion.

PubMed

Karl, Matthias; Scherg, Stefan; Grobecker-Karl, Tanja

Achievement of high insertion torque values indicating good primary stability is a goal during dental implant placement. The objective of this study was to evaluate whether or not two-piece implants made from zirconia ceramic may be damaged as a result of torque application. A total of 10 two-piece zirconia implants were repeatedly inserted into polyurethane foam material with increasing density and decreasing osteotomy size. The insertion torque applied was measured, and implants were checked for fractures by applying the fluorescent penetrant method. Weibull probability of failure was calculated based on the recorded insertion torque values. Catastrophic failures could be seen in five of the implants from two different batches at insertion torques ranging from 46.0 to 70.5 Ncm, while the remaining implants (all belonging to one batch) survived. Weibull probability of failure seems to be low at the manufacturer-recommended maximum insertion torque of 35 Ncm. Chipping fractures at the thread tips as well as tool marks were the only otherwise observed irregularities. While high insertion torques may be desirable for immediate loading protocols, zirconia implants may fracture when manufacturer-recommended insertion torques are exceeded. Evaluating bone quality prior to implant insertion may be useful.

Lithium batteries using poly(ethylene oxide)-based non-aqueous electrolytes

DOEpatents

Chen, Zonghai; Amine, Khalil

2015-09-08

Lithium-air cells employing poly(ethyleneoxide) phosphate-based electrolytes may be prepared and exhibit improved charge carrying capacity. Such PEO phosphates generally have the formulas IIa, IIb, IIc, where: ##STR00001##

Infrared wire-grid polarizer with sol-gel zirconia grating

NASA Astrophysics Data System (ADS)

Yamada, Itsunari; Ishihara, Yoshiro

2017-05-01

The infrared wire-grid polarizer consisting of an Al grating, Si, and sol-gel derived zirconia grating film was fabricated by soft imprint process and Al shadow coating processes. A silicone mold was used because of its low surface energy, flexibility, and capability of transferring submicrosized patterns. As a result, the Al grating with a pitch of 400 nm and a depth of 100 nm was obtained on the zirconia grating film. The fabricated polarizer exhibited a polarization function with the TM transmittance greater than that of the Si substrate in the specific wavelength range of 3.6-8.5 μm, because the zirconia film acted as an antireflection film. The maximum value was 63% at a wavelength of 5.2 μm. This increment of the TM transmission spectrum results in interference within the zirconia film. Also, the extinction ratio exceeded almost 20 dB in the 3-8.8 μm wavelength range.

Masking ability of a zirconia ceramic on composite resin substrate shades.

PubMed

Tabatabaian, Farhad; Shabani, Sima; Namdari, Mahshid; Sadeghpour, Koroush

2017-01-01

Masking ability of a restorative material plays an important role to cover discolored tooth structure; however, this ability has not yet been well understood in zirconia-based restorations. This study assessed the masking ability of a zirconia ceramic on composite resin substrates with different shades. Ten zirconia disc specimens, with 0.5 mm thickness and 10 mm diameter, were fabricated by a computer-aided design/computer-aided manufacturing system. A white substrate (control) and six composite resin substrates with different shades including A1, A2, A3, B2, C2, and D3 were prepared. The substrates had a cylindrical shape with 10 mm diameter and height. The specimens were placed onto the substrates for spectrophotometric evaluation. A spectrophotometer measured the L*, a*, and b* values for the specimens. ΔE values were calculated to determine the color differences between the groups and the control and then were compared with a perceptional threshold (ΔE = 2.6). Repeated measures ANOVA and Bonferroni tests were used for data analysis ( P < 0.05). The mean and standard deviation of ΔE values for A1, A2, A3, B2, C2, and D3 groups were 6.78 ± 1.59, 8.13 ± 1.66, 9.81 ± 2.64, 9.61 ± 1.38, 9.59 ± 2.63, and 8.13 ± 1.89, respectively. A significant difference was found among the groups in the ΔE values ( P = 0.006). The ΔE values were more than the perceptional threshold in all the groups ( P < 0.0001). Within the limitations of this study, it can be concluded that the tested zirconia ceramic could not thoroughly mask different shades of the composite resin substrates. Moreover, color masking of zirconia depends on the shade of substrate.

Operando X-ray Investigation of Electrode/Electrolyte Interfaces in Model Solid Oxide Fuel Cells

PubMed Central

2016-01-01

We employed operando anomalous surface X-ray diffraction to investigate the buried interface between the cathode and the electrolyte of a model solid oxide fuel cell with atomic resolution. The cell was studied under different oxygen pressures at elevated temperatures and polarizations by external potential control. Making use of anomalous X-ray diffraction effects at the Y and Zr K-edges allowed us to resolve the interfacial structure and chemical composition of a (100)-oriented, 9.5 mol % yttria-stabilized zirconia (YSZ) single crystal electrolyte below a La0.6Sr0.4CoO3−δ (LSC) electrode. We observe yttrium segregation toward the YSZ/LSC electrolyte/electrode interface under reducing conditions. Under oxidizing conditions, the interface becomes Y depleted. The yttrium segregation is corroborated by an enhanced outward relaxation of the YSZ interfacial metal ion layer. At the same time, an increase in point defect concentration in the electrolyte at the interface was observed, as evidenced by reduced YSZ crystallographic site occupancies for the cations as well as the oxygen ions. Such changes in composition are expected to strongly influence the oxygen ion transport through this interface which plays an important role for the performance of solid oxide fuel cells. The structure of the interface is compared to the bare YSZ(100) surface structure near the microelectrode under identical conditions and to the structure of the YSZ(100) surface prepared under ultrahigh vacuum conditions. PMID:27346923

High-efficiency and high-power rechargeable lithium–sulfur dioxide batteries exploiting conventional carbonate-based electrolytes

PubMed Central

Park, Hyeokjun; Lim, Hee-Dae; Lim, Hyung-Kyu; Seong, Won Mo; Moon, Sehwan; Ko, Youngmin; Lee, Byungju; Bae, Youngjoon; Kim, Hyungjun; Kang, Kisuk

2017-01-01

Shedding new light on conventional batteries sometimes inspires a chemistry adoptable for rechargeable batteries. Recently, the primary lithium-sulfur dioxide battery, which offers a high energy density and long shelf-life, is successfully renewed as a promising rechargeable system exhibiting small polarization and good reversibility. Here, we demonstrate for the first time that reversible operation of the lithium-sulfur dioxide battery is also possible by exploiting conventional carbonate-based electrolytes. Theoretical and experimental studies reveal that the sulfur dioxide electrochemistry is highly stable in carbonate-based electrolytes, enabling the reversible formation of lithium dithionite. The use of the carbonate-based electrolyte leads to a remarkable enhancement of power and reversibility; furthermore, the optimized lithium-sulfur dioxide battery with catalysts achieves outstanding cycle stability for over 450 cycles with 0.2 V polarization. This study highlights the potential promise of lithium-sulfur dioxide chemistry along with the viability of conventional carbonate-based electrolytes in metal-gas rechargeable systems. PMID:28492225

Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

PubMed Central

Kwon, Taek-Ka; Pak, Hyun-Soon; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun

2013-01-01

PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS The mean fracture strengths were as follows: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain. PMID:23755332

Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns.

PubMed

Kwon, Taek-Ka; Pak, Hyun-Soon; Yang, Jae-Ho; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun; Yeo, In-Sung

2013-05-01

All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. THE MEAN FRACTURE STRENGTHS WERE AS FOLLOWS: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.

In Vitro Cell Proliferation and Mechanical Behaviors Observed in Porous Zirconia Ceramics

PubMed Central

Li, Jing; Wang, Xiaobei; Lin, Yuanhua; Deng, Xuliang; Li, Ming; Nan, Cewen

2016-01-01

Zirconia ceramics with porous structure have been prepared by solid-state reaction using yttria-stabilized zirconia and stearic acid powders. Analysis of its microstructure and phase composition revealed that a pure zirconia phase can be obtained. Our results indicated that its porosity and pore size as well as the mechanical characteristics can be tuned by changing the content of stearic acid powder. The optimal porosity and pore size of zirconia ceramic samples can be effective for the increase of surface roughness, which results in higher cell proliferation values without destroying the mechanical properties. PMID:28773341

Influence of full-contour zirconia surface roughness on wear of glass-ceramics.

PubMed

Luangruangrong, Palika; Cook, N Blaine; Sabrah, Alaa H; Hara, Anderson T; Bottino, Marco C

2014-04-01

The purpose of this study was to evaluate the influence of full-contour (Y-TZP) zirconia surface roughness (glazed vs. as-machined) on the wear behavior of glass-ceramics. Thirty-two full contour Y-TZP (Diazir®) specimens (hereafter referred to as zirconia sliders) (ϕ = 2 mm, 1.5 mm in height) were fabricated using CAD/CAM and sintered according to the manufacturer's instructions. Zirconia sliders were embedded in brass holders using acrylic resin and then randomly assigned (n = 16) according to the surface treatment received, that is, as-machined or glazed. Glass-ceramic antagonists, Empress/EMP and e.max/EX, were cut into tabs (13 × 13 × 2 mm(3) ), wet-finished, and similarly embedded in brass holders. Two-body pin-on-disk wear testing was performed at 1.2 Hz for 25,000 cycles under a 3 kg load. Noncontact profilometry was used to measure antagonist height (μm) and volume loss (mm(3) ). Qualitative data of the zirconia testing surfaces and wear tracks were obtained using SEM. Statistics were performed using ANOVA with a significance level of 0.05. As-machined yielded significantly higher mean roughness values (Ra = 0.83 μm, Rq = 1.09 μm) than glazed zirconia (Ra = 0.53 μm, Rq = 0.78 μm). Regarding glass-ceramic antagonist loss, as-machined zirconia caused significantly less mean height and volume loss (68.4 μm, 7.6 mm(3) ) for EMP than the glazed group (84.9 μm, 9.9 mm(3) ), while no significant differences were found for EX. Moreover, EMP showed significantly lower mean height and volume loss than EX (p < 0.0001). SEM revealed differences on wear characteristics between the glass-ceramics tested. e.max wear was not affected by zirconia surface roughness; however, Empress wear was greater when opposing glazed zirconia. Overall, surface glazing on full-contour zirconia did not minimize glass-ceramic wear when compared with as-machined zirconia. © 2013 by the American College of Prosthodontists.

A sol-powder coating technique for fabrication of yttria stabilised zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wattanasiriwech, Darunee; Wattanasiriwech, Suthee; Stevens, Ron

Yttria stabilised zirconia has been prepared using a simple sol-powder coating technique. The polymeric yttria sol, which was prepared using 1,3 propanediol as a network modifier, was homogeneously mixed with nanocrystalline zirconia powder and it showed a dual function: as a binder which promoted densification and a phase modifier which stabilised zirconia in the tetragonal and cubic phases. Thermal analysis and X-ray diffraction revealed that the polymeric yttria sol which decomposed at low temperature into yttrium oxide could change the m {sup {yields}} t phase transformation behaviour of the zirconia, possibly due to the small particle size and very highmore » surface area of both yttria and zirconia particles allowing rapid alloying. The sintered samples exhibited three crystalline phases: monoclinic, tetragonal and cubic, in which cubic and tetragonal are the major phases. The weight fractions of the individual phases present in the selected specimens were determined using quantitative Rietveld analysis.« less

Electrolyte disorders with platinum-based chemotherapy: mechanisms, manifestations and management.

PubMed

Oronsky, Bryan; Caroen, Scott; Oronsky, Arnold; Dobalian, Vaughn E; Oronsky, Neil; Lybeck, Michelle; Reid, Tony R; Carter, Corey A

2017-11-01

Platinum chemotherapy, particularly cisplatin, is commonly associated with electrolyte imbalances, including hypomagnesemia, hypokalemia, hypophosphatemia, hypocalcemia and hyponatremia. The corpus of literature on these dyselectrolytemias is large; the objective of this review is to synthesize the literature and summarize the mechanisms responsible for these particular electrolyte disturbances in the context of platinum-based treatment as well as to present the clinical manifestations and current management strategies for oncologists and primary care physicians, since the latter are increasingly called on to provide care for cancer patients with medical comorbidities. Correct diagnosis and effective treatment are essential to improved patient outcomes.

Operating mechanisms of electrolytes in magnesium ion batteries: chemical equilibrium, magnesium deposition, and electrolyte oxidation.

PubMed

Kim, Dong Young; Lim, Younhee; Roy, Basab; Ryu, Young-Gyoon; Lee, Seok-Soo

2014-12-21

Since the early nineties there have been a number of reports on the experimental development of Mg electrolytes based on organo/amide-magnesium chlorides and their transmetalations. However, there are no theoretical papers describing the underlying operating mechanisms of Mg electrolytes, and there is no clear understanding of these mechanisms. We have therefore attempted to clarify the operating mechanisms of Mg electrolytes by studying the characteristics of Mg complexes, solvation, chemical equilibrium, Mg-deposition processes, electrolyte-oxidation processes, and oxidative degradation mechanism of RMgCl-based electrolytes, using ab initio calculations. The formation and solvation energies of Mg complexes highly depend on the characteristics of R groups. Thus, changes in R groups of RMgCl lead to changes in the equilibrium position and the electrochemical reduction and oxidation pathways and energies. We first provide a methodological scheme for calculating Mg reduction potential values in non-aqueous electrolytes and electrochemical windows. We also describe a strategy for designing Mg electrolytes to maximize the electrochemical windows and oxidative stabilities. These results will be useful not only for designing improved Mg electrolytes, but also for developing new electrolytes in the future.

The Effect of Zirconia in Hydroxyapatite on Staphylococcus epidermidis Growth.

PubMed

Siswomihardjo, Widowati; Sunarintyas, Siti; Tontowi, Alva Edy

2012-01-01

Synthetic hydroxyapatite (HA) has been widely used and developed as the material for bone substitute in medical applications. The addition of zirconia is needed to improve the strength of hydroxyapatite as the bone substitute. One of the drawbacks in the use of biomedical materials is the occurrence of biomaterial-centred infections. The recent method of limiting the presence of microorganism on biomaterials is by providing biomaterial-bound metal-containing compositions. In this case, S. epidermidis is the most common infectious organism in biomedical-centred infection. Objective. This study was designed to evaluate the effect of zirconia concentrations in hydroxyapatite on the growth of S. epidermidis. Methods and Materials. The subjects of this study were twenty hydroxyapatite discs, divided into four groups in which one was the control and the other three were the treatment groups. Zirconia powder with the concentrations of 20%, 30%, and 40% was added into the three different treatment groups. Scanning electron microscope analysis was performed according to the hydroxyapatite and hydroxyapatite-zirconia specimens. All discs were immersed into S. epidermidis culture for 24 hours and later on they were soaked into a medium of PBS. The cultured medium was spread on mannitol salt agar. After incubation for 24 hours at 37°C , the number of colonies was measured with colony counter. Data obtained were analyzed using the ANOVA followed by the pairwise comparison. Result. The statistical analysis showed that different concentrations of zirconia powder significantly influenced the number of S. epidermidis colony (P < 0.05) . Conclusion. The addition of zirconia into hydroxyapatite affected the growth of S. epidermidis. Hydroxyapatite with 20% zirconia proved to be an effective concentration to inhibit the growth of S. epidermidis colony.

Bioactive and Thermally Compatible Glass Coating on Zirconia Dental Implants

PubMed Central

Kirsten, A.; Hausmann, A.; Weber, M.; Fischer, J.

2015-01-01

The healing time of zirconia implants may be reduced by the use of bioactive glass coatings. Unfortunately, existing glasses are either bioactive like Bioglass 45S5 but thermally incompatible with the zirconia substrate, or they are thermally compatible but exhibit only a very low level of bioactivity. In this study, we hypothesized that a tailored substitution of alkaline earth metals and alkaline metals in 45S5 can lead to a glass composition that is both bioactive and thermally compatible with zirconia implants. A novel glass composition was analyzed using x-ray fluorescence spectroscopy, dilatometry, differential scanning calorimetry, and heating microscopy to investigate its chemical, physical, and thermal properties. Bioactivity was tested in vitro using simulated body fluid (SBF). Smooth and microstructured glass coatings were applied using a tailored spray technique with subsequent thermal treatment. Coating adhesion was tested on implants that were inserted in bovine ribs. The cytocompatibility of the coating was analyzed using L929 mouse fibroblasts. The coefficient of thermal expansion of the novel glass was shown to be slightly lower (11.58·10–6 K–1) than that of the zirconia (11.67·10–6 K–1). After storage in SBF, the glass showed reaction layers almost identical to the bioactive glass gold standard, 45S5. A process window between 800 °C and 910 °C was found to result in densely sintered and amorphous coatings. Microstructured glass coatings on zirconia implants survived a minimum insertion torque of 60 Ncm in the in vitro experiment on bovine ribs. Proliferation and cytotoxicity of the glass coatings was comparable with the controls. The novel glass composition showed a strong adhesion to the zirconia substrate and a significant bioactive behavior in the SBF in vitro experiments. Therefore, it holds great potential to significantly reduce the healing time of zirconia dental implants. PMID:25421839

The Effect of Zirconia in Hydroxyapatite on Staphylococcus epidermidis Growth

PubMed Central

Siswomihardjo, Widowati; Sunarintyas, Siti; Tontowi, Alva Edy

2012-01-01

Synthetic hydroxyapatite (HA) has been widely used and developed as the material for bone substitute in medical applications. The addition of zirconia is needed to improve the strength of hydroxyapatite as the bone substitute. One of the drawbacks in the use of biomedical materials is the occurrence of biomaterial-centred infections. The recent method of limiting the presence of microorganism on biomaterials is by providing biomaterial-bound metal-containing compositions. In this case, S. epidermidis is the most common infectious organism in biomedical-centred infection. Objective. This study was designed to evaluate the effect of zirconia concentrations in hydroxyapatite on the growth of S. epidermidis. Methods and Materials. The subjects of this study were twenty hydroxyapatite discs, divided into four groups in which one was the control and the other three were the treatment groups. Zirconia powder with the concentrations of 20%, 30%, and 40% was added into the three different treatment groups. Scanning electron microscope analysis was performed according to the hydroxyapatite and hydroxyapatite-zirconia specimens. All discs were immersed into S. epidermidis culture for 24 hours and later on they were soaked into a medium of PBS. The cultured medium was spread on mannitol salt agar. After incubation for 24 hours at 37°C , the number of colonies was measured with colony counter. Data obtained were analyzed using the ANOVA followed by the pairwise comparison. Result. The statistical analysis showed that different concentrations of zirconia powder significantly influenced the number of S. epidermidis colony (P < 0.05) . Conclusion. The addition of zirconia into hydroxyapatite affected the growth of S. epidermidis. Hydroxyapatite with 20% zirconia proved to be an effective concentration to inhibit the growth of S. epidermidis colony. PMID:22919390

Electrolyte for EC-V profiling of InP and GaAs based structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faur, M.; Faur, M.; Goradia, M.

Electrochemical C-V (EC-V) profiling is the most often used and convenient method for accurate majority carrier concentration depth profiling of semiconductors. Although, according to the authors, FAP is the best electrolyte for accurate profiling of InP structures, it does not work well with other III-V compounds. To overcome this, recently, the authors have developed a new electrolyte, which they call UNIEL (UNIversal ELectrolyte), which works well with all the materials. However, as with the FAP electrolyte, the presence of HF makes the UNIEL incompatible with the electrochemical cell of Polaron EC-V profilers manufactured by BIO-RAD. By slightly modifying the electrochemicalmore » cell configuration the authors are able to use both the FAP and UNIEL electrolytes, without destroying the calomel electrode. Recently, they have, nevertheless, experimented with variations of the UNIEL with no HF content for EC-V profiling of structures based on InP and GaAs. Presently available results are presented here.« less

In vitro assessment of cutting efficiency and durability of zirconia removal diamond rotary instruments.

PubMed

Kim, Joon-Soo; Bae, Ji-Hyeon; Yun, Mi-Jung; Huh, Jung-Bo

2017-06-01

Recently, zirconia removal diamond rotary instruments have become commercially available for efficient cutting of zirconia. However, research of cutting efficiency and the cutting characteristics of zirconia removal diamond rotary instruments is limited. The purpose of this in vitro study was to assess and compare the cutting efficiency, durability, and diamond rotary instrument wear pattern of zirconia diamond removal rotary instruments with those of conventional diamond rotary instruments. In addition, the surface characteristics of the cut zirconia were assessed. Block specimens of 3 mol% yttrium cation-doped tetragonal zirconia polycrystal were machined 10 times for 1 minute each using a high-speed handpiece with 6 types of diamond rotary instrument from 2 manufacturers at a constant force of 2 N (n=5). An electronic scale was used to measure the lost weight after each cut in order to evaluate the cutting efficiency. Field emission scanning electron microscopy was used to evaluate diamond rotary instrument wear patterns and machined zirconia block surface characteristics. Data were statistically analyzed using the Kruskal-Wallis test, followed by the Mann-Whitney U test (α=.05). Zirconia removal fine grit diamond rotary instruments showed cutting efficiency that was reduced compared with conventional fine grit diamond rotary instruments. Diamond grit fracture was the most dominant diamond rotary instrument wear pattern in all groups. All machined zirconia surfaces were primarily subjected to plastic deformation, which is evidence of ductile cutting. Zirconia blocks machined with zirconia removal fine grit diamond rotary instruments showed the least incidence of surface flaws. Although zirconia removal diamond rotary instruments did not show improved cutting efficiency compared with conventional diamond rotary instruments, the machined zirconia surface showed smoother furrows of plastic deformation and fewer surface flaws. Copyright © 2016 Editorial Council

Shear bond strength of indirect composite material to monolithic zirconia.

PubMed

Sari, Fatih; Secilmis, Asli; Simsek, Irfan; Ozsevik, Semih

2016-08-01

This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia.

An harmonic smile resulted from the use of ceramic prosthesis with zirconia structure: a case report.

PubMed

Tavarez, Rudys Rodolfo de Jesus; Goncalves, Leticia Machado; Dias, Ana Paula; Dias, Anna Claudia Pereira; Malheiros, Adriana Santos; Silva, Alice Carvalho; Bandeca, Matheus Coelho

2014-06-01

The rehabilitation of patients requiring an esthetic smile demands a multidisciplinary approach. This clinical report describes a treatment plan for recovery aesthetics' smile of anterior teeth using ceramic prosthesis with zirconia structure. Initially, a review of aesthetic parameters, diagnostic waxing, mock-up and provisional restorations was performed. A contextual assessment of aesthetic, proportion and shape of teeth was done to recreate a natural looking for teeth in consonance with the smile line. Subsequently, based on these parameters, fixed prostheses of the upper anterior teeth using ceramic restorations with zirconia infrastructures were performed. The use of ceramic restorations with zirconia structures associated with a careful treatment plan allows the professional to integrate esthetic and function for satisfactory clinical results. How to cite the article: Tavarez RR, Gonçalves LM, Dias AP, Dias AC, Malheiros AS, Silva AC, Bandeca MC. An harmonic smile resulted from the use of ceramic prosthesis with zirconia structure: A case report. J Int Oral Health 2014;6(3):90-2.

Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method making the same

DOEpatents

Gerald, II, Rex E.; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL

2011-03-08

The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. A preferred embodiment of the invented electrochemical cell generally comprises a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. A preferred novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

Fracture resistance and reliability of new zirconia posts.

PubMed

Oblak, Cedomir; Jevnikar, Peter; Kosmac, Tomaz; Funduk, Nenad; Marion, Ljubo

2004-04-01

The radicular portion of zirconia endodontic posts often need to be reshaped to achieve a definitive form and may be airborne-particle abraded to improve adhesion during luting. Therefore, the surface of the tetragonal zirconia ceramics may be transformed and damaged, influencing the mechanical properties of the material. This study compared the fracture resistance of prefabricated zirconia posts with a new retentive post-head after different surface treatments. Experimental zirconia posts of 2 different diameters, 1.3 mm and 1.5 mm, were produced from commercially available zirconia powder. A cylindro-conical outline form was used for the root portion of the system and a post-head with 3 retentive rings was designed. Sixty posts of each diameter were divided into 3 groups (n=20). Group 1 was ground with a coarse grit diamond bur; Group 2 was airborne-particle abraded with 110-microm fused alumina particles, and Group 3 was left as-received (controls). Posts were luted into the root-shaped artificial canals with the Clearfil adhesive system and Panavia 21 adhesive resin luting agent. The posts were loaded in a universal testing machine at an inclination of 45 degrees with the constant cross-head speed of 1 mm/min. The fracture load (N) necessary to cause post fracture was recorded, and the statistical significance of differences among groups was analyzed with 1-way ANOVA followed by the Fischer LSD test (alpha=.05). The variability was analyzed using Weibull statistics. Load to fracture values of all zirconia posts depended primarily on post diameter. Mean fracture loads (SD) in Newtons were 518.4 (+/-101.3), 993.6 (+/-224.1), and 622.7 (+/-110.3) for Groups 1 through 3, respectively, for thicker posts, and 385.9 (+/-110.3), 627.0 (+/-115.1), and 451.2 (+/-81.4) for Groups 1 through 3, respectively, for thinner posts. Airborne-particle-abraded posts exhibited significantly higher resistance to fracture (P<.05) than those in the other 2 groups for diameters 1.3 mm

[Evaluation of alumina effects on the mechanical property and translucency of nano-zirconia all-ceramics].

PubMed

Jiang, Li; Zhao, Yong-qi; Zhang, Jing-chao; Liao, Yun-mao; Li, Wei

2010-06-01

To study the effects of alumina content on sintered density, mechanical property and translucency of zirconia nanocomposite all-ceramics. Specimens of zirconia nanocomposite all-ceramics were divided into five groups based on their alumina content which are 0% (control group), 2.5%, 5.0%, 7.5% and 10.0% respectively. The sintered densities were measured using Archimedes' method. Specimens' bending strengths were measured with three-point bending test (ISO 6872). The visible light transmittances were measured with spectrophotometric arrangements and the fractured surfaces were observed using scanning electron microscope (SEM). The control group of pure zirconia could be sintered to the theoretical density under pressure-less sintering condition. The bending strength was (1100.27 ± 54.82) MPa, the fracture toughness was (4.96 ± 0.35) MPa×m(1/2) and the transmittance could reach 17.03%. The sintered density and transmittance decreased as alumina content increased from 2.5% to 10%. However, the fracture toughness only increased slightly. In all four alumina groups, the additions of alumina had no significant effect on samples' bending strengths (P > 0.05). When the content of alumina was 10%, fracture toughness of specimens reached (6.13 ± 0.44) MPa×m(1/2) while samples' transmittance declined to 6.21%. SEM results showed that alumina particles had no significant effect on the grain size and distribution of tetragonal zirconia polycrystals. Additions of alumina to yttria-tetragonal zirconia polycrystals could influence its mechanical property and translucency. Additions of the other phase to zirconia ceramics should meet the clinical demands of strength and esthetics.

Finite Element Analysis of IPS Empress II Ceramic Bridge Reinforced by Zirconia Bar

PubMed Central

Kermanshah, H.; Bitaraf, T.; Geramy, A.

2012-01-01

Objective: The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS –Empress II core ceramics. Materials and Methods: The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB), zirconia bar with vertical trench (VZB) and zirconia bar with horizontal trench (HZB) (cross sections of these bars were circular). The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component and von Mises stresses were evaluated along a defined path. Results: In the connector area, von Mises stress in MPa were approximately identical in the specimens with ZB (at molar connector (MC): 4.75 and at premolar connector (PC): 6.40) and without ZB (MC: 5.50, PC: 6.68), and considerable differences were not recognized. Whereas, Von-Mises stress (MPa) in the specimens with horizontal trenched Zirconia bar (HZB) (MC: 3.91, PC: 2.44) and Vertical trenched Zirconia bar (VZB) (MC: 2.53, PC: 2.56) was decreased considerably. Conclusion: Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures. PMID:23323181

Finite Element Analysis of IPS Empress II Ceramic Bridge Reinforced by Zirconia Bar.

PubMed

Kermanshah, H; Bitaraf, T; Geramy, A

2012-01-01

The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS -Empress II core ceramics. The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB), zirconia bar with vertical trench (VZB) and zirconia bar with horizontal trench (HZB) (cross sections of these bars were circular). The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component and von Mises stresses were evaluated along a defined path. IN THE CONNECTOR AREA, VON MISES STRESS IN MPA WERE APPROXIMATELY IDENTICAL IN THE SPECIMENS WITH ZB (AT MOLAR CONNECTOR (MC): 4.75 and at premolar connector (PC): 6.40) and without ZB (MC: 5.50, PC: 6.68), and considerable differences were not recognized. Whereas, Von-Mises stress (MPa) in the specimens with horizontal trenched Zirconia bar (HZB) (MC: 3.91, PC: 2.44) and Vertical trenched Zirconia bar (VZB) (MC: 2.53, PC: 2.56) was decreased considerably. Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures.

Separators for Li-Ion and Li-Metal Battery Including Ionic Liquid Based Electrolytes Based on the TFSI− and FSI− Anions

PubMed Central

Kirchhöfer, Marija; von Zamory, Jan; Paillard, Elie; Passerini, Stefano

2014-01-01

The characterization of separators for Li-ion or Li-metal batteries incorporating hydrophobic ionic liquid electrolytes is reported herein. Ionic liquids made of N-butyl-N-methylpyrrolidinium (PYR14+) or N-methoxyethyl-N-methylpyrrolidinium (PYR12O1+), paired with bis(trifluoromethanesulfonyl)imide (TFSI−) or bis(fluorosulfonyl)imide (FSI−) anions, were tested in combination with separators having different chemistries and morphologies in terms of wetting behavior, Gurley and McMullin number, as well as Li/(Separator + Electrolyte) interfacial properties. It is shown that non-functionalized microporous polyolefin separators are poorly wetted by FSI−-based electrolytes (contrary to TFSI−-based electrolytes), while the ceramic coated separator Separion® allows good wetting with all electrolytes. Furthermore, by comparing the lithium solid electrolyte interphase (SEI) resistance evolution at open circuit and during cycling, depending on separator morphologies and chemistries, it is possible to propose a scale for SEI forming properties in the order: PYR12O1FSI > PYR14FSI > PYR14TFSI > PYR12O1TFSI. Finally, the impact the separator morphology is evidenced by the SEI resistance evolution and by comparing Li electrodes cycled using separators with two different morphologies. PMID:25153637

Electrolytes

MedlinePlus

... Chloride Magnesium Phosphorus Potassium Sodium Electrolytes can be acids, bases, or salts. They can be measured by different ... Saunders; 2013:464-467. DuBose TD. Disorders of acid-base balance. In: Skorecki K, Chertow GM, Marsden PA, ...

Concerns of Hydrothermal Degradation in CAD/CAM Zirconia

PubMed Central

Kim, J.-W.; Covel, N.S.; Guess, P.C.; Rekow, E.D.; Zhang, Y.

2010-01-01

Zirconia-based restorations are widely used in prosthetic dentistry; however, their susceptibility to hydrothermal degradation remains elusive. We hypothesized that CAD/CAM machining and subsequent surface treatments, i.e., grinding and/or grit-blasting, have marked effects on the hydrothermal degradation behavior of Y-TZP. CAD/CAM-machined Y-TZP plates (0.5 mm thick), both with and without subsequent grinding with various grit sizes or grit-blasting with airborne alumina particles, were subjected to accelerated aging tests in a steam autoclave. Results showed that the CAD/CAM-machined surfaces initially exhibited superior hydrothermal degradation resistance, but deteriorated at a faster rate upon prolonged autoclave treatment compared with ground and grit-blasted surfaces. The accelerated hydrothermal degradation of CAD/CAM surfaces is attributed to the CAD/CAM machining damage and the absence of surface compressive stresses in the fully sintered material. Clinical relevance for surface treatments of zirconia frameworks in terms of hydrothermal and structural stabilities is addressed. PMID:19966039

Surface Modification of Zirconia Substrate by Calcium Phosphate Particles Using Sol-Gel Method.

PubMed

Jin, So Dam; Um, Sang Cheol; Lee, Jong Kook

2015-08-01

Surface modification with a biphasic composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) was performed on a zirconia substrate using a sol-gel method. An initial calcium phosphate sol was prepared by mixing a solution of Ca(NO3)2 · 4H20 and (C2H5O)3P(O), while both porous and dense zirconia were used as substrates. The sol-gel coating was performed using a spin coater. The coated porous zirconia substrate was re-sintered at 1350 °C 2 h, while coated dense zirconia substrate was heat-treated at 750 °C 1 h. The microstructure of the resultant HA/TCP coatings was found to be dependent on the type of zirconia substrate used. With porous zirconia as a starting substrate, numerous isolated calcium phosphate particles (TCP and HA) were uniformly dispersed on the surface, and the particle size and covered area were dependent on the viscosity of the calcium phosphate sol. Conversely, when dense zirconia was used as a starting substrate, a thick film of nano-sized HA particles was obtained after heat treatment, however, substantial agglomeration and cracking was also observed.

Deposition of crystalline hydroxyapatite nano-particle on zirconia ceramic: a potential solution for the poor bonding characteristic of zirconia ceramics to resin cement.

PubMed

Azari, Abbas; Nikzad, Sakineh; Yazdani, Arash; Atri, Faezeh; Fazel Anvari-Yazdi, Abbas

2017-07-01

The poor bonding strength of zirconia to different dental substrates is one of the challenging issues in restorative dentistry. Hydroxyapatite is an excellent biocompatible material with fine bonding properties. In this study, it was hypothesized that hydroxyapatite coating on zirconia would improve its bond strength. Forty-five zirconia blocks were prepared and randomly divided into three groups: hydroxyapatite coating, sandblasting, and no preparation (control). The blocks were bonded to cement and the micro-shear bond strength was measured following load application. The bond strength values were analyzed with the Kruskal-Wallis test in 3 groups and paired comparisons were made using the Mann-Whitney U test. The failure patterns of the specimens were studied by a stereomicroscope and a scanning electron microscope and then analyzed by the chi-square test (significance level = 0.05). Deposition of hydroxyapatite on the zirconia surface significantly improved its bond strength to the resin cement in comparison with the control specimens (p < 0.0001). Also, the bond strength was similar to the sandblasted group (p = 0.34). The sandblasted and control group only showed adhesive failure, but the hydroxyapatite coated group had mixed failures, indicating the better quality of bonding (p < 0.0001). As a final point, hydroxyapatite coating on the zirconia surface improved the bond strength quality and values.

Aqueous-Phase Acetic Acid Ketonization over Monoclinic Zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Qiuxia; Lopez-Ruiz, Juan A.; Cooper, Alan R.

The effect of aqueous phase on the acetic acid ketonization over monoclinic zirconia has been investigated using first-principles based density functional theory (DFT) calculations. To capture the aqueous phase chemistry over the solid zirconia catalyst surface, the aqueous phase is represented by 111 explicit water molecules with a liquid water density of 0.93 g/cm3 and the monoclinic zirconia is modeled by the most stable surface structure . The dynamic nature of aqueous phase/ interface was studied using ab initio molecular dynamics simulation, indicating that nearly half of the surface Zr sites are occupied by either adsorbed water molecules or hydroxylmore » groups at 550 K. DFT calculations show that the adsorption process of acetic acid from the liquid water phase to the surface is nearly thermodynamically neutral with a Gibbs free energy of -2.3 kJ/mol although the adsorption strength of acetic acid on the surface in aqueous phase is much stronger than in vapor phase. Therefore it is expected that the adsorption of acetic acid will dramatically affects aqueous phase ketonization reactivity over the monoclinic zirconia catalyst. Using the same ketonization mechanism via the β-keto acid intermediate, we have compared acetic acid ketonization to acetone in both vapor and aqueous phases. Our DFT calculation results show although the rate-determining step of the β-keto acid formation via the C-C coupling is not pronouncedly affected, the presence of liquid water molecules will dramatically affect dehydrogenation and hydrogenation steps via proton transfer mechanism. This work was financially supported by the United States Department of Energy (DOE)’s Bioenergy Technologies Office (BETO) and performed at the Pacific Northwest National Laboratory (PNNL). PNNL is a multi-program national laboratory operated for DOE by Battelle Memorial Institute. Computing time and advanced catalyst characterization use was granted by a user proposal at the William R. Wiley

Suppressed Sr segregation and performance of directly assembled La0.6Sr0.4Co0.2Fe0.8O3-δ oxygen electrode on Y2O3-ZrO2 electrolyte of solid oxide electrolysis cells

NASA Astrophysics Data System (ADS)

Ai, Na; He, Shuai; Li, Na; Zhang, Qi; Rickard, William D. A.; Chen, Kongfa; Zhang, Teng; Jiang, San Ping

2018-04-01

Active and stable oxygen electrode is probably the most important in the development of solid oxide electrolysis cells (SOECs) technologies. Herein, we report the successful development of mixed ionic and electronic conducting (MIEC) La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite oxides directly assembled on barrier-layer-free yttria-stabilized zirconia (YSZ) electrolyte as highly active and stable oxygen electrodes of SOECs. Electrolysis polarization effectively induces the formation of electrode/electrolyte interface, similar to that observed under solid oxide fuel cell (SOFC) operation conditions. However, in contrast to the significant performance decay under SOFC operation conditions, the cell with directly assembled LSCF oxygen electrodes shows excellent stability, tested for 300 h at 0.5 A cm-2 and 750 °C under SOEC operation conditions. Detailed microstructure and phase analysis reveal that Sr segregation is inevitable for LSCF electrode, but anodic polarization substantially suppresses Sr segregation and migration to the electrode/electrolyte interface, leading to the formation of stable and efficient electrode/electrolyte interface for water and CO2 electrolysis under SOECs operation conditions. The present study demonstrates the feasibility of using directly assembled MIEC cobaltite based oxygen electrodes on barrier-layer-free YSZ electrolyte of SOECs.

Evaluation of a conditioning method to improve core-veneer bond strength of zirconia restorations.

PubMed

Teng, Jili; Wang, Hang; Liao, Yunmao; Liang, Xing

2012-06-01

The high strength and fracture toughness of zirconia have supported its extensive application in esthetic dentistry. However, the fracturing of veneering porcelains remains one of the primary causes of failure. The purpose of this study was to evaluate, with shear bond strength testing, the effect of a simple and novel surface conditioning method on the core-veneer bond strength of a zirconia ceramic system. The shear bond strength of a zirconia core ceramic to the corresponding veneering porcelain was tested by the Schmitz-Schulmeyer method. Thirty zirconia core specimens (10 × 5 × 5 mm) were layered with a veneering porcelain (5 × 3 × 3 mm). Three different surface conditioning methods were evaluated: polishing with up to 1200 grit silicon carbide paper under water cooling, airborne-particle abrasion with 110 μm alumina particles, and modification with zirconia powder coating before sintering. A metal ceramic system was used as a control group. All specimens were subjected to shear force in a universal testing machine at a crosshead speed of 0.5 mm/min. The shear bond strength values were analyzed with 1-way ANOVA and Tukey's post hoc pairwise comparisons (α=.05). The fractured specimens were examined with a scanning electron microscope to observe the failure mode. The mean (SD) shear bond strength values in MPa were 47.02 (6.4) for modified zirconia, 36.66 (8.6) for polished zirconia, 39.14 (6.5) for airborne-particle-abraded zirconia, and 46.12 (7.1) for the control group. The mean bond strength of the control (P=.028) and modified zirconia groups (P=.014) was significantly higher than that of the polished zirconia group. The airborne-particle-abraded group was not significantly different from any other group. Scanning electron microscopy evaluation showed that cohesive fracture in the veneering porcelain was the predominant failure mode of modified zirconia, while the other groups principally fractured at the interface. Modifying the zirconia surface

Ionic Liquid Hybrid Electrolytes for Lithium-Ion Batteries: A Key Role of the Separator-Electrolyte Interface in Battery Electrochemistry.

PubMed

Huie, Matthew M; DiLeo, Roberta A; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2015-06-10

Batteries are multicomponent systems where the theoretical voltage and stoichiometric electron transfer are defined by the electrochemically active anode and cathode materials. While the electrolyte may not be considered in stoichiometric electron-transfer calculations, it can be a critical factor determining the deliverable energy content of a battery, depending also on the use conditions. The development of ionic liquid (IL)-based electrolytes has been a research area of recent reports by other researchers, due, in part, to opportunities for an expanded high-voltage operating window and improved safety through the reduction of flammable solvent content. The study reported here encompasses a systematic investigation of the physical properties of IL-based hybrid electrolytes including quantitative characterization of the electrolyte-separator interface via contact-angle measurements. An inverse trend in the conductivity and wetting properties was observed for a series of IL-based electrolyte candidates. Test-cell measurements were undertaken to evaluate the electrolyte performance in the presence of functioning anode and cathode materials, where several promising IL-based hybrid electrolytes with performance comparable to that of conventional carbonate electrolytes were identified. The study revealed that the contact angle influenced the performance more significantly than the conductivity because the cells containing IL-tetrafluoroborate-based electrolytes with higher conductivity but poorer wetting showed significantly decreased performance relative to the cells containing IL-bis(trifluoromethanesulfonyl)imide electrolytes with lower conductivity but improved wetting properties. This work contributes to the development of new IL battery-based electrolyte systems with the potential to improve the deliverable energy content as well as safety of lithium-ion battery systems.

Comparison of peri-implant bone formation around injection-molded and machined surface zirconia implants in rabbit tibiae

PubMed Central

Kim, Hong-Kyun; Woo, Kyung mi; Shon, Won-Jun; Ahn, Jin-Soo; Cha, Seunghee; Park, Young-Seok

2017-01-01

The aim of this study was to compare osseointegration and surface characteristics of zirconia implants made by the powder injection molding (PIM) technique and made by the conventional milling procedure in rabbit tibiae. Surface characteristics of 2 types of implant were evaluated. Sixteeen rabbits received 2 types of external hex implants with similar geometry, machined zirconia implants and PIM zirconia implants, in the tibiae. Removal torque tests and histomorphometric analyses were performed. The roughness of PIM zirconia implants was higher than that of machined zirconia implants. The PIM zirconia implants exhibited significantly higher bone-implant contact and removal torque values than the machined zirconia implants (P < 0.001). The osseointegration of the PIM zirconia implant is promising, and PIM, using the roughened mold etching technique, can produce substantially rough surfaces on zirconia implants. PMID:26235717

Fracture loads and failure modes of customized and non-customized zirconia abutments.

PubMed

Moris, Izabela Cristina Maurício; Chen, Yung-Chung; Faria, Adriana Cláudia Lapria; Ribeiro, Ricardo Faria; Fok, Alex Sui-Lun; Rodrigues, Renata Cristina Silveira

2018-05-05

This study aimed to evaluate the fracture load and pattern of customized and non-customized zirconia abutments with Morse-taper connection. 18 implants were divided into 3 groups according to the abutments used: Zr - with non-customized zirconia abutments; Zrc - with customized zirconia abutments; and Ti - with titanium abutments. To test their load capacity, a universal test machine with a 500-kgf load cell and a 0.5-mm/min speed were used. After, one implant-abutment assembly from each group was analyzed by Scanning Electron Microscopy (SEM). For fractographic analysis, the specimens were transversely sectioned above the threads of the abutment screw in order to examine their fracture surfaces using SEM. A significant difference was noted between the groups (Zr=573.7±11.66N, Zrc=768.0±8.72N and Ti=659.1±7.70N). Also, the zirconia abutments fractured while the titanium abutments deformed plastically. Zrc presented fracture loads significantly higher than Zr (p=0.009). All the zirconia abutments fractured below the implant platform, starting from the area of contact between the abutment and implant and propagating to the internal surface of the abutment. All the zirconia abutments presented complete cleavage in the mechanical test. Fractography detected differences in the position and pattern of fracture between the two groups with zirconia abutments, probably because of the different diameters in the transmucosal region. Customization of zirconia abutments did not affect their fracture loads, which were comparable to that of titanium and much higher than the maximum physiological limit for the anterior region of the maxilla. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Translucency of zirconia copings made with different CAD/CAM systems.

PubMed

Baldissara, Paolo; Llukacej, Altin; Ciocca, Leonardo; Valandro, Felipe L; Scotti, Roberto

2010-07-01

Zirconia cores are reported to be less translucent than glass, lithium disilicate, or alumina cores. This could affect the esthetic appearance and the clinical choices made when using zirconia-based restorations. The purpose of this in vitro study was to evaluate the translucency of zirconia copings for single crowns fabricated using different CAD/CAM systems, using lithium disilicate glass ceramic as a control. Using impressions made from a stainless steel complete-crown master die, 9 stone cast replicas were fabricated, numbered, and distributed into 8 ceramic ZrO(2) CAD/CAM system groups (Lava Frame 0.3 and 0.5, IPS e.max ZirCAD, VITA YZ, Procera AllZircon, Digizon, DC Zircon, and Cercon Base) and to a lithium disilicate glass-ceramic control group (IPS e.max Press) using a simple computer-generated randomization method. From each die, the manufacturer's authorized milling centers supplied 5 copings per group without applying any dying technique to the ceramic base material. The copings were prepared to allow for a 40-mum cement layer and were of different thicknesses according to system specifications. Translucency was measured by the direct transmission method with a digital photoradiometer mounted in a dark chamber. The light source was a 150-W halogen lamp beam. Measurements were repeated 3 times for each specimen. Data obtained were analyzed using 1-way ANOVA and the Bonferroni multiple comparison test (alpha=.05). Among ZrO(2) copings, Lava (0.3 mm and 0.5 mm thick) showed the highest (P<.05) values of translucency measured as light flow units (3.572 + or - 018 x 10(3) lx and 3.181 + or - 0.13 x 10(3) lx, respectively). These values represent 71.7% and 63.9%, respectively, of the glass-ceramic control group (4.98 x 10(3) lx). All ZrO(2) copings demonstrated different levels of light transmission, with the 2 Lava specimens showing the highest values. Translucency of zirconia copings was significantly lower (P=.001) than that of the lithium disilicate glass

Non-aqueous aluminium-air battery based on ionic liquid electrolyte

NASA Astrophysics Data System (ADS)

Revel, Renaud; Audichon, Thomas; Gonzalez, Serge

2014-12-01

A promising metal-air secondary battery based on aluminium-oxygen couple is described. In this paper, we observed that an aluminium-air battery employing EMImCl, AlCl3 room temperature ionic liquid (RTIL) as electrolyte and aluminium as negative electrode, has an exceptional reduced self-discharged rate. Due to its new and innovative type of electrolyte, this aluminium-air battery can support relatively high current densities (up to 0.6 mA cm-2) and an average voltage of 0.6-0.8 V. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self-sustained energy source.

Effects of surface chemistry and microstructure of electrolyte on oxygen reduction kinetics of solid oxide fuel cells

DOE PAGES

Park, Joong Sun; An, Jihwan; Lee, Min Hwan; ...

2015-11-01

In this study, we report systematic investigation of the surface properties of yttria-stabilized zirconia (YSZ) electrolytes with the control of the grain boundary (GB) density at the surface, and its effects on electrochemical activities. The GB density of thin surface layers deposited on single crystal YSZ substrates is controlled by changing the annealing temperature (750-1450 °C). Higher oxygen reduction reactions (ORR) kinetics is observed in samples annealed at lower temperatures. The higher ORR activity is ascribed to the higher GB density at the YSZ surface where 'mobile' oxide ion vacancies are more populated. Meanwhile, oxide ion vacancies concurrently created withmore » yttrium segregation at the surface at the higher annealing temperature are considered inactive to oxygen incorporation reactions. Our results provide additional insight into the interplay between the surface chemistry, microstructures, and electrochemical activity. They potentially provide important guidelines for engineering the electrolyte electrode interfaces of solid oxide fuel cells for higher electrochemical performance.« less

Advances in the electrodeposition of aluminum from ionic liquid based electrolytes

NASA Astrophysics Data System (ADS)

Leadbetter, Kirt C.

Aluminum plating is of considerable technical and economic interest because it provides an eco-friendly substitute for cadmium coatings used on many military systems. However, cadmium has been determined to be a significant environmental safety and occupational health (ESOH) hazard because of its toxicity and carcinogenic nature. Furthermore, the cost of treating and disposing of generated wastes, which often contain cyanide, is costly and is becoming prohibitive in the face of increasingly stringent regulatory standards. The non-toxic alternative aluminum is equivalent or superior in performance to cadmium. In addition, it could serve to provide an alternative to hexavalent chromium coatings used on military systems for similar reasons to that of cadmium. Aluminum is a beneficial alternative in that it demonstrates self-healing corrosion resistance in the form of a tightly-bound, impervious oxide layer. A successfully plated layer would be serviceable over a wider temperature range, 925 °F for aluminum compared to 450 oF for cadmium. In addition, an aluminum layer can be anodized to make it non-conducting and colorable. In consideration of the plating process, aluminum cannot be deposited from aqueous solutions because of its reduction potential. Therefore, nonaqueous electrolytes are required for deposition. Currently, aluminum can be electrodeposited in nonaqueous processes that use hazardous chemicals such as toluene and pyrophoric aluminum alkyls. Electrodeposition from ionic liquids provides the potential for a safer method that could be easily scaled up for industrial application. The plating process could be performed at a lower temperature and higher current density than other commercially available aluminum electrodeposition processes; thus a reduced process cost could be possible. The current ionic liquid based electrolytes are more expensive; however production on a larger scale and a long electrolyte lifetime are associated with a reduction in price

Thermodynamic properties of some metal oxide-zirconia systems

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1989-01-01

Metal oxide-zirconia systems are a potential class of materials for use as structural materials at temperatures above 1900 K. These materials must have no destructive phase changes and low vapor pressures. Both alkaline earth oxide (MgO, CaO, SrO, and BaO)-zirconia and some rare earth oxide (Y2O3, Sc2O3, La2O3, CeO2, Sm2O3, Gd2O3, Yb2O3, Dy2O3, Ho2O3, and Er2O3)-zirconia system are examined. For each system, the phase diagram is discussed and the vapor pressure for each vapor species is calculated via a free energy minimization procedure. The available thermodynamic literature on each system is also surveyed. Some of the systems look promising for high temperature structural materials.

Tetragonal zirconia quantum dots in silica matrix prepared by a modified sol-gel protocol

NASA Astrophysics Data System (ADS)

Verma, Surbhi; Rani, Saruchi; Kumar, Sushil

2018-05-01

Tetragonal zirconia quantum dots (t-ZrO2 QDs) in silica matrix with different compositions ( x)ZrO2-(100 - x)SiO2 were fabricated by a modified sol-gel protocol. Acetylacetone was added as a chelating agent to zirconium propoxide to avoid precipitation. The powders as well as thin films were given thermal treatment at 650, 875 and 1100 °C for 4 h. The silica matrix remained amorphous after thermal treatment and acted as an inert support for zirconia quantum dots. The tetragonal zirconia embedded in silica matrix transformed into monoclinic form due to thermal treatment ≥ 1100 °C. The stability of tetragonal phase of zirconia is found to enhance with increase in silica content. A homogenous dispersion of t-ZrO2 QDs in silica matrix was indicated by the mapping of Zr, Si and O elements obtained from scanning electron microscope with energy dispersive X-ray analyser. The transmission electron images confirmed the formation of tetragonal zirconia quantum dots embedded in silica. The optical band gap of zirconia QDs (3.65-5.58 eV) was found to increase with increase in zirconia content in silica. The red shift of PL emission has been exhibited with increase in zirconia content in silica.

Shear bond strength of indirect composite material to monolithic zirconia

PubMed Central

2016-01-01

PURPOSE This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI). MATERIALS AND METHODS Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05). RESULTS Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05). CONCLUSION Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia. PMID:27555895

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes.

PubMed

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-17

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf(2)]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g(-1) at a current density of 2 A g(-1), when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg(-1) and 41 Wh kg(-1), respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes

NASA Astrophysics Data System (ADS)

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-01

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g-1 at a current density of 2 A g-1, when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg-1 and 41 Wh kg-1, respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

Elaboration of Alumina-Zirconia Composites: Role of the Zirconia Content on the Microstructure and Mechanical Properties

PubMed Central

Naglieri, Valentina; Palmero, Paola; Montanaro, Laura; Chevalier, Jérôme

2013-01-01

Alumina-zirconia (AZ) composites are attractive structural materials, which combine the high hardness and Young’s modulus of the alumina matrix with additional toughening effects, due to the zirconia dispersion. In this study, AZ composites containing different amounts of zirconia (in the range 5–20 vol %) were prepared by a wet chemical method, consisting on the surface coating of alumina powders by mixing them with zirconium salt aqueous solutions. After spray-drying, powders were calcined at 600 °C for 1 h. Green bodies were then prepared by two methods: uniaxial pressing of spray-dried granules and slip casting of slurries, obtained by re-dispersing the spray dried granulates. After pressureless sintering at 1500 °C for 1 h, the slip cast samples gave rise to fully dense materials, characterized by a quite homogeneous distribution of ZrO2 grains in the alumina matrix. The microstructure, phase composition, tetragonal to monoclinic transformation behavior and mechanical properties were investigated and are here discussed as a function of the ZrO2 content. The material containing 10 vol % ZrO2 presented a relevant hardness and exhibited the maximum value of KI0, mainly imputable to the t → m transformation at the crack tip. PMID:28809262

Effect of high intensity ultrasound on the mesostructure of hydrated zirconia

NASA Astrophysics Data System (ADS)

Kopitsa, G. P.; Baranchikov, A. E.; Ivanova, O. S.; Yapryntsev, A. D.; Grigoriev, S. V.; Pranzas, P. Klaus; Ivanov, V. K.

2012-02-01

We report structural changes in amorphous hydrated zirconia caused by high intensity ultrasonic treatment studied by means of small-angle neutron scattering (SANS) and X-ray diffraction (XRD). It was established that sonication affects the mesostructure of ZrO2×xH2O gels (i.e. decreases their homogeneity, increases surface fractal dimension and the size of monomer particles). Ultrasound induced structural changes in hydrated zirconia governs its thermal behaviour, namely decreases the rate of tetragonal to monoclinic zirconia phase transition.

Comparison of edge chipping resistance of PFM and veneered zirconia specimens

PubMed Central

Quinn, Janet B.; Sundar, Veeraraghavan; Parry, Edward E.; Quinn, George D.

2011-01-01

Objectives To investigate the chipping resistance of veneered zirconia specimens and compare it to the chipping resistance of porcelain fused to metal (PFM) specimens. Methods Veneered zirconia and PFM bar specimens were prepared in clinically relevant thicknesses. The specimen edges were chipped with different magnitude forces, producing chips of various sizes. The range of sizes included small chips that did not penetrate all the way through the veneers to the substrates, and also chips that were very large and reached the zirconia or metal substrates. The relationship between force magnitude and chip size (edge distance) was graphed. The resulting curves were compared for the veneered zirconia and PFM specimens. Knoop hardness vs. force graphs for the veneers and substrates were also obtained. Results The zirconia and PFM veneer chipping data followed a power law (coefficient of determination, R2 > 0.93) as expected from the literature. The curves overlapped within the combined data scatter, indicating similar resistance to chipping. The chips made in both types of specimens detached and did not penetrate into the substrate when they reached the veneer/substrate intersections. The hardness–load curves for the veneers and substrates all exhibited an indentation size effect (ISE) at low loads. The Knoop hardness values with uncertainties of ±one standard deviation at 4 N loads for the metal, zirconia, and the metal and zirconia veneers are: (2.02 ± 0.08, 12.01 ± 0.39, 4.24 ± 0.16 and 4.36 ± 0.02 GPa), respectively, with no statistically significant difference between the veneers (Tukey pairwise comparison at 0.95 family confidence). Significance This work indicates that a similar resistance to chipping might be expected for veneered zirconia and PFM restorations, in spite of the large difference in substrate hardness. Differences in susceptibility to chip spalling were not detected, but the chips in both specimen types detached off the sides in a similar

Zirconia based superhydrophobic coatings on cotton fabrics exhibiting excellent durability for versatile use

PubMed Central

Das, Indranee; De, Goutam

2015-01-01

A fluorinated silyl functionalized zirconia was synthesized by the sol-gel method to fabricate an extremely durable superhydrophobic coating on cotton fabrics by simple immersion technique. The fabric surfaces firmly attached with the coating material through covalent bonding, possessed superhydrophobicity with high water contact angle ≈163 ± 1°, low hysteresis ≈3.5° and superoleophilicity. The coated fabrics were effective to separate oil/water mixture with a considerably high separation efficiency of 98.8 wt% through ordinary filtering. Presence of highly stable (chemically and mechanically) superhydrophobic zirconia bonded with cellulose makes such excellent water repelling ability of the fabrics durable under harsh environment conditions like high temperature, strong acidic or alkaline solutions, different organic solvents and mechanical forces including extensive washings. Moreover, these coated fabrics retained self-cleanable superhydrophobic property as well as high water separation efficiency even after several cycles, launderings and abrasions. Therefore, such robust superhydrophobic ZrO2 coated fabrics have strong potential for various industrial productions and uses. PMID:26678754

Development of gas chromatographic methods for the analyses of organic carbonate-based electrolytes

NASA Astrophysics Data System (ADS)

Terborg, Lydia; Weber, Sascha; Passerini, Stefano; Winter, Martin; Karst, Uwe; Nowak, Sascha

2014-01-01

In this work, novel methods based on gas chromatography (GC) for the investigation of common organic carbonate-based electrolyte systems are presented, which are used in lithium ion batteries. The methods were developed for flame ionization detection (FID), mass spectrometric detection (MS). Further, headspace (HS) sampling for the investigation of solid samples like electrodes is reported. Limits of detection are reported for FID. Finally, the developed methods were applied to the electrolyte system of commercially available lithium ion batteries as well as on in-house assembled cells.

Non-flammable polyphosphonate electrolytes

NASA Astrophysics Data System (ADS)

Dixon, Brian G.; Morris, R. Scott; Dallek, Steven

This research is directed towards the development of safe, and thermally stable polymeric electrolytes. Advanced electrolytes are described, including thermal test data, which are ionically highly conductive, and non-flammable. These novel multi-heteropolymer electrolytes represent a significant advance in the design of high-performance rechargeable lithium systems that possess superior safety and handling characteristics. Representative results are shown by the figures contained in this text. These DSC/TGA results compare a typical liquid carbonate-based electrolyte system, ethylene carbonate and ethyl methyl carbonate, with novel polyphosphonates as synthesized in this program. These tests were performed with the electrolytes in combination with lithium metal, and the impressive relative thermal stability of the phosphonates is apparent.

Tailoring the electrode-electrolyte interface of Solid Oxide Fuel Cells (SOFC) by laser micro-patterning to improve their electrochemical performance

NASA Astrophysics Data System (ADS)

Cebollero, J. A.; Lahoz, R.; Laguna-Bercero, M. A.; Larrea, A.

2017-08-01

Cathode activation polarisation is one of the main contributions to the losses of a Solid Oxide Fuel Cell. To reduce this loss we use a pulsed laser to modify the surface of yttria stabilized zirconia (YSZ) electrolytes to make a corrugated micro-patterning in the mesoscale. The beam of the laser source, 5 ns pulse width and emitting at λ = 532 nm (green region), is computer-controlled to engrave the selected micro-pattern on the electrolyte surface. Several laser scanning procedures and geometries have been tested. Finally, we engrave a square array with 28 μm of lattice parameter and 7 μm in depth on YSZ plates. With these plates we prepare LSM-YSZ/YSZ/LSM-YSZ symmetrical cells (LSM: La1-xSrxMnO3) and determine their activation polarisation by Electrochemical Impedance Spectroscopy (EIS). To get good electrode-electrolyte contact after sintering it is necessary to use pressure-assisted sintering with low loads (about 5 kPa), which do not modify the electrode microstructure. The decrease in polarisation with respect to an unprocessed cell is about 30%. EIS analysis confirms that the reason for this decrease is an improvement in the activation processes at the electrode-electrolyte interface.

Enhanced structural stability of nanoporous zirconia under irradiation of He

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Tengfei; Huang, Xuejun; Wang, Chenxu

2012-01-01

This work reports a greatly enhanced tolerance for He irradiation-induced swelling in nanocrystalline zirconia film with interconnected nanoporous structure (hereinafter referred as to NC-C). Compared to bulk yttria-stabilized zirconia (YSZ) and another nanocrystalline zirconia film only with discrete nano voids (hereinafter referred as to NC-V), the NC-C film reveals good tolerance for irradiation of high-fluence He. No appreciable surface blistering can be found even at the highest fluence of 6 1017 cm2 in NCC film. From TEM analysis of as-irradiated samples, the enhanced tolerance for volume swelling in NCC film is attributed to the enhanced diffusion mechanism of deposited Hemore » via widely distributed nano channels. Furthermore, the growth of grain size is quite small for both nanocrystalline zirconia films after irradiation, which is ascribed to the decreasing of area of grain boundary due to loose structure and low energy of primary knock-on atoms for He ions.« less

Evaluation of a new carbon/zirconia-based sorbent for the cleanup of food extracts in multiclass analysis of pesticides and environmental contaminants

USDA-ARS?s Scientific Manuscript database

A novel carbon/zirconia based material, SupelTM QuE Verde (Verde), was evaluated in a filter-vial dispersive solid phase extraction (d-SPE) cleanup of QuEChERS extracts of pork, salmon, kale, and avocado for residual analysis of pesticides and environmental contaminants. Low pressure (LP) GC-MS/MS w...

Effects of multiple firings on the microstructure of zirconia and veneering ceramics.

PubMed

Alkurt, Murat; Yeşil Duymus, Zeynep; Gundogdu, Mustafa

2016-01-01

The aim of study was to evaluate the effects of multiple firings on the microstructures of zirconia and two ceramics. Vita VM9 (VMZ) and Cerabien ZR (C-Z) ceramics on a zirconia framework and zirconia without veneering ceramic (WO-Z) were evaluated. Firing methods included firing two, five, and ten times (n=10). The effects of multiple firings on the surface hardness of the materials were evaluated using a Vickers hardness (HV) tester. Data were analyzed by two-way ANOVA and Tukey's test (α=0.05). After firing five and ten times, the hardness of VM-Z and C-Z increased significantly (p<0.001). The HVs of the Cerabien ZR and Vita VM9 veneering ceramics were similar (p>0.05). In the XRD analysis, zirconia had similar tetragonal (t)-monoclinic (m) phase transformations of Y-TZP after the different firing times. Clinically, multiple firings did not affect the microstructure of zirconia, but the structures of the two ceramics were affected.

Bioactive and thermally compatible glass coating on zirconia dental implants.

PubMed

Kirsten, A; Hausmann, A; Weber, M; Fischer, J; Fischer, H

2015-02-01

The healing time of zirconia implants may be reduced by the use of bioactive glass coatings. Unfortunately, existing glasses are either bioactive like Bioglass 45S5 but thermally incompatible with the zirconia substrate, or they are thermally compatible but exhibit only a very low level of bioactivity. In this study, we hypothesized that a tailored substitution of alkaline earth metals and alkaline metals in 45S5 can lead to a glass composition that is both bioactive and thermally compatible with zirconia implants. A novel glass composition was analyzed using x-ray fluorescence spectroscopy, dilatometry, differential scanning calorimetry, and heating microscopy to investigate its chemical, physical, and thermal properties. Bioactivity was tested in vitro using simulated body fluid (SBF). Smooth and microstructured glass coatings were applied using a tailored spray technique with subsequent thermal treatment. Coating adhesion was tested on implants that were inserted in bovine ribs. The cytocompatibility of the coating was analyzed using L929 mouse fibroblasts. The coefficient of thermal expansion of the novel glass was shown to be slightly lower (11.58 · 10(-6) K(-1)) than that of the zirconia (11.67 · 10(-6) K(-1)). After storage in SBF, the glass showed reaction layers almost identical to the bioactive glass gold standard, 45S5. A process window between 800 °C and 910 °C was found to result in densely sintered and amorphous coatings. Microstructured glass coatings on zirconia implants survived a minimum insertion torque of 60 Ncm in the in vitro experiment on bovine ribs. Proliferation and cytotoxicity of the glass coatings was comparable with the controls. The novel glass composition showed a strong adhesion to the zirconia substrate and a significant bioactive behavior in the SBF in vitro experiments. Therefore, it holds great potential to significantly reduce the healing time of zirconia dental implants. © International & American Associations for Dental

Aluminum oxyhydroxide based separator/electrolyte and battery system, and a method of making the same

DOEpatents

Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL

2011-02-15

The instant invention relates a solid-state electrochemical cell and a novel separator/electrolyte incorporated therein. The invented electrochemical cell generally comprising: a unique metal oxyhydroxide based (i.e. AlOOH) separator/electrolyte membrane sandwiched between a first electrode and a second electrode. The novel separator/electrolyte comprises a nanoparticulate metal oxyhydroxide, preferably AlOOH and a salt which are mixed and then pressed together to form a monolithic metal oxyhydroxide-salt membrane.

Experimental research on the relationship between fit accuracy and fracture resistance of zirconia abutments.

PubMed

Sui, Xinxin; Wei, Huasha; Wang, Dashan; Han, Yan; Deng, Jing; Wang, Yongliang; Wang, Junjun; Yang, Jianjun

2014-10-01

The purpose of the study was to investigate the correlation between fit accuracy and fracture resistance of zirconia abutments, as well as its feasibility for clinical applications. Twenty self-made zirconia abutments were tested with 30 Osstem GSII implants. First, 10 Osstem GSII implants were cut into two parts along the long axis and assembled with the zirconia abutments. The microgaps between the implants and the zirconia abutments were measured under a scanning electron microscope. Second, the zirconia abutments were assembled with 20 un-cut implants and photographed before and after being fixed with a central screw of 30-Ncm torque. The dental films were measured by Digora for Windows 2.6 software. Then the fracture resistance of zirconia abutments was measured using the universal testing machine at 90°. All results were analyzed using SPSS13.0 software. The average internal-hexagon microgaps between the implants and zirconia abutments were 19.38±1.34μm. The average Morse taper microgap in the implant-abutment interface was 17.55±1.68μm. The dental film showed that the Morse taper gap in the implant-abutment interface disappeared after being fixed with a central screw of 30-Ncm torque, and the average moving distance of the zirconia abutments to the implants was 0.19±0.02mm. The average fracture resistance of zirconia abutments was 282.93±17.28N. The internal-hexagon microgap between the implants and zirconia abutments was negatively related to the fracture resistance of the abutments (r1=-0.97, p<0.01). The Morse taper microgap in the implant-abutment interface was negatively related to the fracture resistance of the abutments (r2=-0.84, p<0.01). The microgap between implant and abutment was negatively related to the fracture resistance of the abutment, while the internal-hexagon microgap has better correlation than the Morse taper microgap. The closure of microgap is helpful to improve the fracture resistance of zirconia abutments. The fracture

Electrolyte and Acid-Base Disturbances in End-Stage Liver Disease: A Physiopathological Approach.

PubMed

Jiménez, José Víctor; Carrillo-Pérez, Diego Luis; Rosado-Canto, Rodrigo; García-Juárez, Ignacio; Torre, Aldo; Kershenobich, David; Carrillo-Maravilla, Eduardo

2017-08-01

Electrolyte and acid-base disturbances are frequent in patients with end-stage liver disease; the underlying physiopathological mechanisms are often complex and represent a diagnostic and therapeutic challenge to the physician. Usually, these disorders do not develop in compensated cirrhotic patients, but with the onset of the classic complications of cirrhosis such as ascites, renal failure, spontaneous bacterial peritonitis and variceal bleeding, multiple electrolyte, and acid-base disturbances emerge. Hyponatremia parallels ascites formation and is a well-known trigger of hepatic encephalopathy; its management in this particular population poses a risky challenge due to the high susceptibility of cirrhotic patients to osmotic demyelination. Hypokalemia is common in the setting of cirrhosis: multiple potassium wasting mechanisms both inherent to the disease and resulting from its management make these patients particularly susceptible to potassium depletion even in the setting of normokalemia. Acid-base disturbances range from classical respiratory alkalosis to high anion gap metabolic acidosis, almost comprising the full acid-base spectrum. Because most electrolyte and acid-base disturbances are managed in terms of their underlying trigger factors, a systematic physiopathological approach to their diagnosis and treatment is required.

Simple Heat Treatment of Zirconia Ceramic Pre-Treated with Silane Primer to Improve Resin Bonding.

PubMed

Ha, Jung-Yun; Son, Jun Sik; Kim, Kyo-Han; Kwon, Tae-Yub

2015-01-01

Establishing a strong resin bond to dental zirconia ceramic remains difficult. Previous studies have shown that the conventional application of silane does not work well with zirconia. This paper reports that a silane pre-treatment of dental zirconia ceramic combined with subsequent heat treatment has potential as an adhesive cementation protocol for improving zirconia-resin bonding. Among the various concentrations (0.1 to 16 vol%) of experimental γ-methacryloxypropyltrimethoxysilane (γ-MPTS) primers assessed, the 1% solution was found to be the most effective in terms of the shear bond strength of the resin cement to dental zirconia ceramic. A high shear bond strength (approx. 30 MPa) was obtained when zirconia specimens were pre-treated with this primer and then heat-treated in a furnace for 60 min at 150 degrees C. Heat treatment appeared to remove the hydrophilic constituents from the silane film formed on the zirconia ceramic surface and accelerate the condensation reactions between the silanol groups of the hydrolyzed silane molecules at the zirconia/resin interface, finally making a more desirable surface for bonding with resin. This estimation was supported by Fourier transform infrared spectroscopy of the silanes prepared in this study.

[Application of plasma sprayed zirconia coating in dental implant: study in implant].

PubMed

Huang, Z F; Wang, Z F; Li, C H; Hao, D; Lan, J

2018-04-09

Objective: To investigate the osseointegration of a novel coating-plasma-sprayed zirconia in dental implant. Methods: Zirconia coating on non-thread titanium implant was prepared using plasma spraying, the implant surface morphology, surface roughness and wettability were measured. In vivo , zirconia coated implants were inserted in rabbit tibia and animals were respectively sacrificed at 2, 4, 8 and 12 weeks after implantation. The bond strength between implant and bone was measured by push-out test. The osseointegration was observed by scanning electron microscopy (SEM), micro CT and histological analyses. Quantified parameters including removal torque, and bone-implant contact (BIC) percentage were calculated. Results: The surface roughness (1.6 µm) and wettability (54.6°) of zirconia coated implant was more suitable than those of titanium implant (0.6 µm and 74.4°) for osseointegration. At 12 weeks, the push-out value of zirconia coated implant and titanium implant were (64.9±3.0) and (50.4±2.9) N, and BIC value of these two groups were (54.7±3.6)% and (41.5±3.6)%. All these differences had statistical significance. Conclusions: The surface characters of zirconia coated implant were more suitable for osseointegration and present better osseointegration than smooth titanium implant in vivo , especially at early stage.

Effect of Porosity of Alumina and Zirconia Ceramics toward Pre-Osteoblast Response

PubMed Central

Hadjicharalambous, Chrystalleni; Prymak, Oleg; Loza, Kateryna; Buyakov, Ales; Kulkov, Sergei; Chatzinikolaidou, Maria

2015-01-01

It is acknowledged that cellular responses are highly affected by biomaterial porosity. The investigation of this effect is important for the development of implanted biomaterials that integrate with bone tissue. Zirconia and alumina ceramics exhibit outstanding mechanical properties and are among the most popular implant materials used in orthopedics, but few data exist regarding the effect of porosity on cellular responses to these materials. The present study investigates the effect of porosity on the attachment and proliferation of pre-osteoblastic cells on zirconia and alumina. For each composition, ceramics of three different porosities are fabricated by sintering, and characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray powder diffraction. Cell proliferation is quantified, and microscopy is employed to qualitatively support the proliferation results and evaluate cell morphology. Cell adhesion and metabolic activity are found comparable among low porosity zirconia and alumina. In contrast, higher porosity favors better cell spreading on zirconia and improves growth, but does not significantly affect cell response on alumina. Between the highest porosity materials, cell response on zirconia is found superior to alumina. Results show that an average pore size of ~150 μm and ~50% porosity can be considered beneficial to cellular growth on zirconia ceramics. PMID:26579516

The Application of a Novel Ceramic Liner Improves Bonding between Zirconia and Veneering Porcelain

PubMed Central

Lee, Hee-Sung

2017-01-01

The adhesion of porcelain to zirconia is a key factor in the success of bilayered restorations. In this study, the efficacy of a novel experimental liner (EL) containing zirconia for improved bonding between zirconia and veneering porcelain was tested. Four ELs containing various concentrations (0, 3.0, 6.0, and 9.0 wt %) of zirconia were prepared. Testing determined the most effective EL (EL3 containing 3.0 wt % zirconia) in terms of shear bond strength value (n = 15). Three different bar-shaped zirconia/porcelain bilayer specimens were prepared for a three-point flexural strength (TPFS) test (n = 15): no-liner (NL), commercial liner (CL), and EL3. Specimens were tested for TPFS with the porcelain under tension and the maximum load was measured at the first sign of fracture. The strength data were analyzed using one-way ANOVA and Tukey’s test (α = 0.05) as well as Weibull distribution. When compared to NL, the CL application had no effect, while the EL3 application had a significant positive effect (p < 0.001) on the flexural strength. Weibull analysis also revealed the highest shape and scale parameters for group EL3. Within the limitations of this study, the novel ceramic liner containing 3.0 wt % zirconia (EL3) significantly enhanced the zirconia/porcelain interfacial bonding. PMID:28869512

Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia.

PubMed

Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH) 2 , nano-MgO, and nano-Zr(OH) 4 . A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were -583.892 (NaOH), -569.048 [Ca(OH) 2 ], -547.393 (MgO), and -530.279 kJ/mol [Zr(OH) 4 ]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH) 2 > MgO > Zr(OH) 4 . Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH) 4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH) 4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic.

Alkaline nanoparticle coatings improve resin bonding of 10-methacryloyloxydecyldihydrogenphosphate-conditioned zirconia

PubMed Central

Qian, Mengke; Lu, Zhicen; Chen, Chen; Zhang, Huaiqin; Xie, Haifeng

2016-01-01

Creating an alkaline environment prior to 10-methacryloyloxydecyldihydrogenphosphate (MDP) conditioning improves the resin bonding of zirconia. The present study evaluated the effects of four alkaline coatings with different water solubilities and pH values on resin bonding of MDP-conditioned zirconia. Two alkaline nanoparticle coatings were studied in particular. Thermodynamics calculations were performed to evaluate the strengths of MDP-tetragonal phase zirconia chemical bonds at different pH values. Zirconia surfaces with and without alkaline coatings were characterized by scanning electron microscope (SEM)/energy dispersive spectrometer and Fourier transform infrared spectroscopy; alkaline coatings included NaOH, Ca(OH)2, nano-MgO, and nano-Zr(OH)4. A shear bond strength (SBS) test was performed to evaluate the effects of the four alkaline coatings on bonding; the alkaline coatings were applied to the surfaces prior to conditioning the zirconia with MDP-containing primers. Gibbs free energies of the MDP-tetragonal zirconia crystal model coordination reaction in different pH environments were −583.892 (NaOH), −569.048 [Ca(OH)2], −547.393 (MgO), and −530.279 kJ/mol [Zr(OH)4]. Thermodynamic calculations indicated that the alkaline coatings improved bonding in the following order: NaOH > Ca(OH)2 > MgO > Zr(OH)4. Statistical analysis of SBS tests showed a different result. SBSs were significantly different in groups that had different alkaline coatings, but it was not influenced by different primers. All four alkaline coatings increased SBS compared to control groups. Of the four coatings, nano-Zr(OH)4 and -MgO showed higher SBS. Therefore, preparing nano-Zr(OH)4 or -MgO coatings prior to conditioning with MDP-containing primers may potentially improve resin bonding of zirconia in the clinic. PMID:27785013

Physico-mechanical and morphological features of zirconia substituted hydroxyapatite nano crystals

PubMed Central

Mansour, S. F.; El-dek, S. I.; Ahmed, M. K.

2017-01-01

Zirconia doped Hydroxyapatite (HAP) nanocrystals [Ca10(PO4)6−x(ZrO2)x(OH)2]; (0 ≤ x ≤ 1 step 0.2) were synthesized using simple low cost facile method. The crystalline phases were examined by X-ray diffraction (XRD). The crystallinity percentage decreased with increasing zirconia content for the as-synthesized samples. The existence of zirconia as secondary phase on the grain boundaries; as observed from scanning electron micrographs (FESEM); resulted in negative values of microstrain. The crystallite size was computed and the results showed that it increased with increasing annealing temperature. Thermo-gravimetric analysis (TGA) assured the thermal stability of the nano crystals over the temperature from room up to 1200 °C depending on the zirconia content. The corrosion rate was found to decrease around 25 times with increasing zirconia content from x = 0.0 to 1.0. Microhardness displayed both compositional and temperature dependence. For the sample (x = 0.6), annealed at 1200 °C, the former increased up to 1.2 times its original value (x = 0.0). PMID:28256557

Nonflammable Perfluoropolyether Electrolytes for Safer Lithiumbased Batteries

NASA Astrophysics Data System (ADS)

Olson, Kevin Raymond

The importance of batteries to sustainable energy is widely recognized. Lithium-ion batteries (LIBs) not only power handheld electronics but also are increasingly being implemented in electric vehicles and "smart-grid" applications to store energy from intermittent solar and wind sources, making sustainable energy a reality. Unfortunately, LIBs contain a highly flammable solvent and can exhibit catastrophic failure, as was brought to the public's attention by the Boeing 787, Samsung Galaxy Note 7, hoverboard, and Tesla battery fires. Thus, realizing the full potential of LIBs in large-scale systems requires the development of nonflammable electrolytes. Perfluoropolyether (PFPE)-based electrolytes address many of the shortcomings of conventional carbonate-based electrolytes or polymer electrolytes such as poly(ethylene oxide). PFPE-based electrolytes transport lithium more efficiently than conventional electrolytes, which has important implications on long-term battery performance. PFPEs make interesting electrolyte solvents because they are nonflammable, nonvolatile, liquid across a broad temperature range, chemically stable, and interact favorably with the anion of fluorinated salts. In this work, the molecular underpinnings for ion transport in PFPE electrolytes will be established by systematically probing how PFPE structure affects electrolyte performance including ionic conductivity, diffusivity, and transference number. End group polarity, end group concentration, and PFPE molecular weight all have important implications on electrolyte performance.

In-situ Preparation of Polymer-Coated Zirconia Nanoparticles by Decomposition of Zirconium-Tert-Butoxide

DTIC Science & Technology

2003-01-01

coated under conditions C are slightly yellow coloured. The zirconia powders collected at position 1 is white. Table I: Plasma parameters of the...pulsed) 99 1 39 40 2,5 2,5 379 400D. 2000 1000 - 20 0 40 4 140 20 [°1 Figure 2: XRD diffractrogram of zirconia powder coated with polymer Zirconia...wave nunter [crn"] Figure 3: FTIR spectra of plasma treated zirconia powders collected at position 2 (coated) prepared under A) continuous plasma B

Interface toughness of a zirconia-veneer system and the effect of a liner application.

PubMed

Wang, Gaoqi; Zhang, Song; Bian, Cuirong; Kong, Hui

2014-09-01

Chipping of veneering porcelain and delamination of a zirconia-veneer interface are 2 common clinical failure modes for zirconia-based restorations and may be partially due to weak interface bonding. The effect of liner on the bond strength of the interface has not been clearly identified. The purpose of the research was to evaluate the interface toughness between the zirconia core and veneering porcelain by means of a fracture mechanics test and to assess the effect of liner on the bond strength of the interface. Thirty bilayered beam-shape specimens were prepared and divided into 2 groups according to liner application. The specimens in each group were subdivided into 3 subgroups in accordance with 3 different veneer thicknesses. A fracture mechanics test was used on each specimen, and the energy release rate, G, and phase angle, ψ, were calculated according to the experimental results. A video microscope was used to monitor the crack propagation, and a scanning electron microscope was used to identify the fracture mode after testing. Two-way ANOVA and the Tukey honestly significant difference test were performed to analyze the experimental data (α=.05) . At each phase angle, the interfaces without a liner had higher mean G values than the interfaces with a liner. Both of the interfaces showed mixed failure mode with thin layers of a veneer or a liner that remained on the zirconia surfaces. Liner application before veneering reduced the interface toughness between zirconia and veneer. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Nanoporous Hybrid Electrolytes for High-Energy Batteries Based on Reactive Metal Anodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, Zhengyuan; Zachman, Michael J.; Choudhury, Snehashis

2017-01-06

Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high-energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high-surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ-Al2O3 ceramics with pore diameters below a cut-off value above 200 nm exhibit long-term stability even atmore » a current density of 3 mA cm-2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.« less

Comparison of shear bond strength of orthodontic brackets using various zirconia primers.

PubMed

Lee, Ji-Yeon; Kim, Jin-Seok; Hwang, Chung-Ju

2015-07-01

The aim of this study was to compare the shear bond strength (SBS) of orthodontic brackets bonded to zirconia surfaces using three different zirconia primers and one silane primer, and subjected to thermocycling. We designed 10 experimental groups following the surface treatment and thermocycling. The surface was treated with one of the following method: no-primer (NP), Porcelain Conditioner (PC), Z-PRIME Plus (ZP), Monobond Plus (MP) and Zirconia Liner Premium (ZL) (n=20). Then each group was subdivided to non-thermocycled and thermocycled groups (NPT, PC, ZPT, MPT, ZLT) (n=10). Orthodontic brackets were bonded to the specimens using Transbond™ XT Paste and light cured for 15 s at 1,100 mW/cm(2). The SBS was measured at a 1 mm/min crosshead speed. The failure mode was assessed by examination with a stereomicroscope and the amount of bonding resin remaining on the zirconia surface was scored using the modified adhesive remnant index (ARI). The SBS of all experimental groups decreased after thermocycling. Before thermocycling, the SBS was ZL, ZP ≥ MP ≥ PC > NP but after thermocycling, the SBS was ZLT ≥ MPT ≥ ZPT > PCT = NPT (p > 0.05). For the ARI score, both of the groups lacking primer (NP and NPT) displayed adhesive failure modes, but the groups with zirconia primers (ZP, ZPT, MP, MPT, ZL, and ZLT) were associated with mixed failure modes. Surface treatment with a zirconia primer increases the SBS relative to no-primer or silane primer application between orthodontic brackets and zirconia prostheses.

Electrodeposition of thin yttria-stabilized zirconia layers using glow-discharge plasma

NASA Astrophysics Data System (ADS)

Ogumi, Zempachi; Uchimoto, Yoshiharu; Tsuji, Yoichiro; Takehara, Zen-ichiro

1992-08-01

A novel process for preparation of thin yttria-stabilized zirconia (YSZ) layers was developed. This process differs from other vapor-phase deposition methods in that a dc bias circuit, separate from the plasma-generation circuit, is used for the electrodeposition process. The YSZ layer was electrodeposited from ZrCl4 and YCl3 on a nonporous calcia-stabilized zirconia substrate. Scanning electron microscopy, electron probe microanalysis, electron spectroscopy for chemical analysis, and x-ray-diffraction measurements confirmed the electrodeposition of a smooth, pinhole-free yttria-stabilized zirconia film of about 3 μm thickness.

High power density solid oxide fuel cells

DOEpatents

Pham, Ai Quoc; Glass, Robert S.

2004-10-12

A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

Method of Fabrication of High Power Density Solid Oxide Fuel Cells

DOEpatents

Pham, Ai Quoc; Glass, Robert S.

2008-09-09

A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O(LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

Novel thixotropic gel electrolytes based on dicationic bis-imidazolium salts for quasi-solid-state dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kim, Jun Young; Kim, Tae Ho; Kim, Dong Young; Park, Nam-Gyu; Ahn, Kwang-Duk

Novel thixotropic gel electrolytes have been successfully prepared by utilizing oligomeric poly(ethylene oxide) (PEO)-based bis-imidazolium diiodide salts and hydrophilic silica nanoparticles for application in quasi-solid-state dye-sensitized solar cells (DSSCs). The thixotropic gel-state of the ionic liquid-based composite electrolytes is confirmed by observing the typical hysteresis loop and temporary hydrogen bonding. On using the PEO-based composite electrolyte, a quasi-solid-state DSSC exhibited highly improved properties such as easy penetration of the electrolyte into the cell without leakage, long-term stability, high open-circuit voltage without the use of 4- tert-butylpyridine, and a high energy-conversion efficiency of 5.25% under AM 1.5 illumination (100 mW cm -2).

Zirconia dental implants degradation by confocal Raman microspectroscopy: analytical simulation and experiments

PubMed Central

Djaker, Nadia; Wulfman, Claudine; Sadoun, Michaël; Lamy de la Chapelle, Marc

2013-01-01

Subsurface hydrothermal degradation of yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) is presented. Evaluation of low temperature degradation (LTD) phase transformation induced by aging in 3Y-TZP is experimentally studied by Raman confocal microspectroscopy. A non-linear distribution of monoclinic volume fraction is determined in depth by using different pinhole sizes. A theoretical simulation is proposed based on the convolution of the excitation intensity profile and the Beer-Lambert law (optical properties of zirconia) to compare between experiment and theory. The calculated theoretical degradation curves matche closely to the experimental ones. Surface transformation (V0) and transformation factor in depth (T) are obtained by comparing simulation and experience for each sample with nondestructive optical sectioning. PMID:23667788

Electrode-Electrolyte Interfaces in Lithium-Sulfur Batteries with Liquid or Inorganic Solid Electrolytes.

PubMed

Yu, Xingwen; Manthiram, Arumugam

2017-11-21

Electrode-electrolyte interfacial properties play a vital role in the cycling performance of lithium-sulfur (Li-S) batteries. The issues at an electrode-electrolyte interface include electrochemical and chemical reactions occurring at the interface, formation mechanism of interfacial layers, compositional/structural characteristics of the interfacial layers, ionic transport across the interface, and thermodynamic and kinetic behaviors at the interface. Understanding the above critical issues is paramount for the development of strategies to enhance the overall performance of Li-S batteries. Liquid electrolytes commonly used in Li-S batteries bear resemblance to those employed in traditional lithium-ion batteries, which are generally composed of a lithium salt dissolved in a solvent matrix. However, due to a series of unique features associated with sulfur or polysulfides, ether-based solvents are generally employed in Li-S batteries rather than simply adopting the carbonate-type solvents that are generally used in the traditional Li + -ion batteries. In addition, the electrolytes of Li-S batteries usually comprise an important additive, LiNO 3 . The unique electrolyte components of Li-S batteries do not allow us to directly take the interfacial theories of the traditional Li + -ion batteries and apply them to Li-S batteries. On the other hand, during charging/discharging a Li-S battery, the dissolved polysulfide species migrate through the battery separator and react with the Li anode, which magnifies the complexity of the interfacial problems of Li-S batteries. However, current Li-S battery development paths have primarily been energized by advances in sulfur cathodes. Insight into the electrode-electrolyte interfacial behaviors has relatively been overshadowed. In this Account, we first examine the state-of-the-art contributions in understanding the solid-electrolyte interphase (SEI) formed on the Li-metal anode and sulfur cathode in conventional liquid-electrolyte

In vitro fracture resistance of three commercially available zirconia crowns for primary molars.

PubMed

Townsend, Janice A; Knoell, Patrick; Yu, Qingzhao; Zhang, Jian-Feng; Wang, Yapin; Zhu, Han; Beattie, Sean; Xu, Xiaoming

2014-01-01

The purpose of this study was to measure the fracture resistance of primary mandibular first molar zirconia crowns from three different manufacturers-EZ Pedo (EZP), NuSmile (NSZ), and Kinder Krowns (KK)-and compare it with the thickness of the zirconia crowns and the measured fracture resistance of preveneered stainless steel crowns (SSCs). The thickness of 20 zirconia crowns from three manufacturers were measured. The mean force required to fracture the crowns was determined. Preveneered NuSmile (NSW) SSCs were tested as a control. EZP crowns were significantly thicker in three of the six measured locations. The force required to fracture the EZP crown was significantly higher than that required for NSZ and KK. There was a positive correlation between fracture resistance and crown thickness in the mesial, distal, mesioocclusal, and distoocclusal dimensions. None of the zirconia crowns proved to be as resistant to fracture as the preveneered SSCs. Statistically significant differences were found among the forces required to fracture zirconia crowns by three different manufacturers. The increase in force correlated with crown thickness. The forces required to fracture the preveneered stainless steel crowns were greater than the forces required to fracture all manufacturers' zirconia crowns.

Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

2012-01-01

Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

Reactivity of nonaqueous organic electrolytes towards lithium

NASA Technical Reports Server (NTRS)

Shen, D. H.; Subbarao, S.; Deligiannis, F.; Huang, C.-K.; Halpert, G.

1990-01-01

The successful operation of an ambient temperature secondary lithium cell is primarily dependent on the stability of the electrolyte towards lithium. The lithium electrode on open circuit must be inert towards the electrolyte to achieve a long shelf life. The reactivity of tetrahydrofuran and 2-methyltetrahydrofuran based electrolytes with additives such as 2-methylfuran, ethylene carbonate, propylene carbonate, and 3-methylsulfolane was investigated by microcalorimetry and ac impedance spectroscopy techniques. Also the stability of electrolytes by open circuit stand tests was studied. Addition of ethylene carbonate and 2-methylfuran additives was found to improve the stability of tetrahydrofuran and 2-methyltetrahydrofuran based electrolytes. Long term microcalorimetry and ac impedance data clearly confirmed the higher stability of ethylene carbonate/2-methyltetrahydrofuran electrolyte compared to the 2-methyltetrahydrofuran and propylene carbonate/2-methyltetrahydrofuran electrolytes.

Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

NASA Astrophysics Data System (ADS)

Zhu, J. W.; Yang, D. W.

2007-07-01

In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance.

PubMed

Wotango, Aselefech Sorsa; Su, Wei-Nien; Haregewoin, Atetegeb Meazah; Chen, Hung-Ming; Cheng, Ju-Hsiang; Lin, Ming-Hsien; Wang, Chia-Hsin; Hwang, Bing-Joe

2018-05-09

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and Solid Electrolyte Interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at sub-zero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-Chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents - ethylene carbonate (EC), and fluoroethylene carbonate (FEC). The formation of an efficient passivation layer in propylene carbonate (PC) -based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation-deintercalation of lithium ions.

Ethylene carbonate-free fluoroethylene carbonate-based electrolyte works better for freestanding Si-based composite paper anodes for Li-ion batteries

NASA Astrophysics Data System (ADS)

Yao, K.; Zheng, J. P.; Liang, R.

2018-03-01

Fluoroethylene carbonate (FEC)-based electrolytes using FEC as the co-solvent (50 wt%) are investigated and compared with the electrolyte using FEC as the additive (10 wt%) for freestanding Si-carbon nanotubes (CNTs) composite paper anodes for Li-ion batteries. The ethylene carbonate (EC)-free FEC-based electrolyte is found to achieve higher specific capacity and better capacity retention in terms of long-term cycling. After 500 cycles, the capacity retention of the cell using diethyl carbonate (DEC)-FEC (1:1 w/w) is increased by 88% and 60% compared to the cells using EC-DEC-FEC (45:45:10 w/w/w) and EC-FEC (1:1 w/w), respectively. Through SEM-EDX and XPS analyses, a possible reaction route of formation of fluorinated semicarbonates and polyolefins from FEC is proposed. The inferior cell performance related to the EC-containing electrolytes is likely due to the formation of more polyolefins, which do not favor Li ion migration.

Effect of Polishing Systems on Surface Roughness and Topography of Monolithic Zirconia.

PubMed

Goo, C L; Yap, Auj; Tan, Kbc; Fawzy, A S

2016-01-01

This study evaluated the effect of different chairside polishing systems on the surface roughness and topography of monolithic zirconia. Thirty-five monolithic zirconia specimens (Lava PLUS, 3M ESPE) were fabricated and divided into five groups of seven and polished with the following: Group 1 (WZ)-Dura white stone followed by Shofu zirconia polishing kit; Group 2 (SZ)-Shofu zirconia polishing kit; Group 3 (CE)-Ceramiste porcelain polishers; Group 4 (CM)-Ceramaster porcelain polishers; and Group 5 (KZ)-Komet ZR zirconia polishers. All specimens were ground with a fine-grit diamond bur prior to polishing procedures to simulate clinical finishing. Baseline and post-polishing profilometric readings were recorded and delta Ra values (difference in mean surface roughness before and after polishing) were computed and analyzed using one-way analysis of variance and Scheffe post hoc test (p<0.05). Representative scanning electron microscopy (SEM) images of the ground but unpolished and polished specimens were acquired. Delta Ra values ranged from 0.146 for CE to 0.400 for KZ. Delta Ra values for KZ, WZ, and SZ were significantly greater than for CE. Significant differences in delta Ra values were also observed between KZ and CM. The SEM images obtained were consistent with the profilometric findings. Diamond-impregnated polishing systems were more effective than silica carbide-impregnated ones in reducing the surface roughness of ground monolithic zirconia.

Fracture and Fatigue Resistance of Cemented versus Fused CAD-on Veneers over Customized Zirconia Implant Abutments.

PubMed

Nossair, Shereen Ahmed; Aboushelib, Moustafa N; Morsi, Tarek Salah

2015-01-05

To evaluate the fracture mechanics of cemented versus fused CAD-on veneers on customized zirconia implant abutments. Forty-five identical customized CAD/CAM zirconia implant abutments (0.5 mm thick) were prepared and seated on short titanium implant abutments (Ti base). A second scan was made to fabricate 45 CAD-on veneers (IPS Empress CAD, A2). Fifteen CAD-on veneers were cemented on the zirconia abutments (Panavia F2.0). Another 15 were fused to the zirconia abutments using low-fusing glass, while manually layered veneers served as control (n = 15). The restorations were subjected to artificial aging (3.2 million cycles between 5 and 10 kg in a water bath at 37°C) before being axially loaded to failure. Fractured specimens were examined using scanning electron microscopy to detect fracture origin, location, and size of critical crack. Stress at failure was calculated using fractography principles (alpha = 0.05). Cemented CAD-on restorations demonstrated significantly higher (F = 72, p < 0.001) fracture load compared to fused CAD-on and manually layered restorations. Fractographic analysis of fractured specimens indicated that cemented CAD-on veneers failed due to radial cracks originating from the veneer/resin interface. Branching of the critical crack was observed in the bulk of the veneer. Fused CAD-on veneers demonstrated cohesive fracture originating at the thickest part of the veneer ceramic, while manually layered veneers failed due to interfacial fracture at the zirconia/veneer interface. Within the limitations of this study, cemented CAD-on veneers on customized zirconia implant abutments demonstrated higher fracture than fused and manually layered veneers. © 2014 by the American College of Prosthodontists.

Superior capacitive performance of hydrochar-based porous carbons in aqueous electrolytes.

PubMed

Fuertes, Antonio B; Sevilla, Marta

2015-03-01

Biomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g(-1) in H2 SO4 and >190 F g(-1) in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2 SO4. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adaptation of zirconia crowns created by conventional versus optical impression: in vitro study

PubMed Central

Bahrami, Babak; Fossoyeux, InÈs; Atash, Ramin

2017-01-01

PURPOSE The aim of this study was to compare the precision of optical impression (Trios, 3Shape) versus that of conventional impression (Imprint IV, 3M-ESPE) with three different margins (shoulder, chamfer, and knife-edge) on Frasaco teeth. MATERIALS AND METHODS The sample comprised of 60 zirconia half-crowns, divided into six groups according to the type of impression and margin. Scanning electron microscopy enabled us to analyze the gap between the zirconia crowns and the Frasaco teeth, using ImageJ software, based on eight reproducible and standardized measuring points. RESULTS No statistically significant difference was found between conventional impressions and optical impressions, except for two of the eight points. A statistically significant difference was observed between the three margin types; the chamfer and knife-edge finishing lines appeared to offer better adaptation results than the shoulder margin. CONCLUSION Zirconia crowns created from optical impression and those created from conventional impression present similar adaptation. While offering identical results, the former have many advantages. In view of our findings, we believe the chamfer margin should be favored. PMID:28680553

Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming.

PubMed

Oh, Gye-Jeong; Yun, Kwi-Dug; Lee, Kwang-Min; Lim, Hyun-Pil; Park, Sang-Won

2010-09-01

The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest® ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.

Sodium-oxygen batteries with alkyl-carbonate and ether based electrolytes.

PubMed

Kim, Jinsoo; Lim, Hee-Dae; Gwon, Hyeokjo; Kang, Kisuk

2013-03-14

Recently, metal-air batteries, such as lithium-air and zinc-air systems, have been studied extensively as potential candidates for ultra-high energy density storage devices because of their exceptionally high capacities. Here, we report such an electrochemical system based on sodium, which is abundant and inexpensive. Two types of sodium-oxygen batteries were introduced and studied, i.e. with carbonate and non-carbonate electrolytes. Both types could deliver specific capacities (2800 and 6000 mA h g(-1)) comparable to that of lithium-oxygen batteries but with slightly lower discharge voltages (2.3 V and 2.0 V). The reaction mechanisms of sodium-oxygen batteries in carbonate and non-carbonate electrolytes were investigated and compared with those of lithium-oxygen batteries.

Shear bond strength between an indirect composite layering material and feldspathic porcelain-coated zirconia ceramics.

PubMed

Fushiki, Ryosuke; Komine, Futoshi; Blatz, Markus B; Koizuka, Mai; Taguchi, Kohei; Matsumura, Hideo

2012-10-01

This study aims to evaluate the effect of both feldspathic porcelain coating of zirconia frameworks and priming agents on shear bond strength between an indirect composite material and zirconia frameworks. A total of 462 airborne-particle-abraded zirconia disks were divided into three groups: untreated disks (ZR-AB), airborne-particle-abraded zirconia disks coated with feldspathic porcelain, (ZR-PO-AB), and hydrofluoric acid-etched zirconia disks coated with feldspathic porcelain (ZR-PO-HF). Indirect composite (Estenia C&B) was bonded to zirconia specimens with no (CON) or one of four priming agents--Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + activator), Estenia Opaque primer, or Porcelain Liner M Liquid B (PLB)--with or without an opaque material (Estenia C&B Opaque). All specimens were tested for shear bond strength before and after 20,000 thermocycles. The Steel-Dwass test and Mann-Whitney U test were used to compare shear bond strength. In ZR-AB specimens, the initial bond strength of the CPB and CPB + Activator groups was significantly higher as compared with the other three groups (P < 0.05), whereas the PLB and CPB + Activator groups had the highest pre- and post-thermocycling bond strengths in ZR-PO-AB and ZR-PO-HF specimens. Among CON disks without opaque material, bond strength was significantly lower in ZR-AB specimens than in ZR-PO-AB and ZR-PO-HF specimens (P < 0.05). Feldspathic porcelain coating of a Katana zirconia framework enhanced the bond strength of Estenia C&B indirect composite to zirconia independent of surface treatment. The use of a silane coupling agent and opaque material yields durable bond strength between the indirect composite and feldspathic-porcelain-coated zirconia. The results of the present study suggest that feldspathic porcelain coating of zirconia frameworks is an effective method to obtain clinically acceptable bond strengths of a layering indirect

Influence of zirconia framework thickness on residual stress profile in veneering ceramic: measurement by hole-drilling.

PubMed

Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

2012-04-01

Framework design is reported to influence chipping in zirconia-based restorations, which is an important cause of failure of such restorations. Residual stress profile in the veneering ceramic after the manufacturing process is an important predictive factor of the mechanical behavior of the material. The objective of this study is to investigate the influence of framework thickness on the stress profile measured in zirconia-based structures. The stress profile was measured with the hole-drilling method in bilayered disc samples of 20mm diameter with a 1.5 mm thick veneering ceramic layer. Six different framework thicknesses from 0.5 mm to 3 mm were studied. Two different cooling procedures were also investigated. Compressive stresses were observed in the surface, and tensile stresses in the depth of most of the samples. The slow cooling procedure was found to promote the development of interior tensile stresses, except for the sample with a 3mm thick framework. With the tempering procedure, samples with a 1.5 mm thick framework exhibited the most favorable stress profile, while thicker and thinner frameworks exhibited respectively in surface or interior tensile stresses. The measurements performed highlight the importance of framework thickness, which determine the nature of stresses and can explain clinical failures encountered, especially with thin frameworks. The adequate ratio between veneering ceramic and zirconia is hard to define, restricting the range of indications of zirconia-based restorations until a better understanding of such a delicate veneering process is achieved. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Strength degradation and lifetime prediction of dental zirconia ceramics under cyclic normal loading.

PubMed

Li, Wanzhong; Xu, Yingqiang; He, Huiming; Zhao, Haidan; Sun, Jian; Hou, Yue

2015-01-01

Clinical cases show that zirconia restoration could happen fracture by accident under overloading after using a period of time. The purpose of this study is to research mechanical behavior and predict lifetime of dental zirconia ceramics under cyclic normal contact loading with experiments. Cyclic normal contact loading test and three point bending test are carried on specimens made of two brands of dental zirconia ceramic to obtain flexure strength and damage degree after different number of loading cycles. By means of damage mechanics model, damage degree under different number of contact loading cycles are calculated according to flexure strength, and verified by SEM photographs of cross section morphology of zirconia ceramics specimen phenomenologically. Relation curve of damage degree and number of cycles is fitted by polynomial fitting, then the number of loading cycles can be concluded when the specimen is complete damage. Strength degradation of two brands dental zirconia ceramics are researched in vitro, and prediction method of contact fatigue lifetime is established.

Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) Using Silver -Base Brazes

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Shpargel, Tarah P.; Asthana, Rajiv

2005-01-01

Three silver-base brazes containing either noble metal palladium (Palcusil-10 and Palcusil-15) or active metal titanium (Ticusil) were evaluated for high-temperature oxidation resistance, and their effectiveness in joining yttria stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel. Thermogravimetric analysis (TGA), and optical- and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) were used to evaluate the braze oxidation behavior and the structure and chemistry of the YSZ/braze/steel joints. The effect of the braze type and processing conditions on the interfacial microstructure and composition of the joint regions is discussed with reference to the chemical changes that occur at the interface. It was found that chemical interdiffusion of the constituents of YSZ, steel and the brazes led to compositional changes and/or interface reconstruction, and metallurgically sound joints.

Electrolytic cell stack with molten electrolyte migration control

DOEpatents

Kunz, H. Russell; Guthrie, Robin J.; Katz, Murray

1988-08-02

An electrolytic cell stack includes inactive electrolyte reservoirs at the upper and lower end portions thereof. The reservoirs are separated from the stack of the complete cells by impermeable, electrically conductive separators. Reservoirs at the negative end are initially low in electrolyte and the reservoirs at the positive end are high in electrolyte fill. During stack operation electrolyte migration from the positive to the negative end will be offset by the inactive reservoir capacity. In combination with the inactive reservoirs, a sealing member of high porosity and low electrolyte retention is employed to limit the electrolyte migration rate.

Electrolytic cell stack with molten electrolyte migration control

DOEpatents

Kunz, H.R.; Guthrie, R.J.; Katz, M.

1987-03-17

An electrolytic cell stack includes inactive electrolyte reservoirs at the upper and lower end portions thereof. The reservoirs are separated from the stack of the complete cells by impermeable, electrically conductive separators. Reservoirs at the negative end are initially low in electrolyte and the reservoirs at the positive end are high in electrolyte fill. During stack operation electrolyte migration from the positive to the negative end will be offset by the inactive reservoir capacity. In combination with the inactive reservoirs, a sealing member of high porosity and low electrolyte retention is employed to limit the electrolyte migration rate. 5 figs.

Zirconia toughened mica glass ceramics for dental restorations.

PubMed

Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

2018-03-01

The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Zirconia crowns for rehabilitation of decayed primary incisors: an esthetic alternative.

PubMed

Ashima, G; Sarabjot, K Bhatia; Gauba, K; Mittal, H C

2014-01-01

Esthetic management of extensively decayed primary maxillary anterior teeth requiring full coronal coverage restoration is usually challenging to the pediatric dentists especially in very young children. Many esthetic options have been tried over the years each having its own advantages, disadvantages and associated technical, functional or esthetic limitations. Zirconia crowns have provided a treatment alternative to address the esthetic concerns and ease of placement of extra-coronal restorations on primary anterior teeth. The present article presents a case where grossly decayed maxillary primary incisors were restored esthetically and functionally with ready made zirconia crowns (ZIRKIZ, HASS Corp; Korea). After endodontic treatment the decayed teeth were restored with zirconia crowns. Over a 30 months period, the crowns have demonstrated good retention and esthetic results. Dealing with esthetic needs in children with extensive loss of tooth structure, using Zirconia crowns would be practical and successful. The treatment described is simple and effective and represents a promising alternative for rehabilitation of decayed primary teeth.

Effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations: in vitro study of color masking ability

PubMed Central

Oh, Seon-Hee

2015-01-01

PURPOSE The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. MATERIALS AND METHODS Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ø10 mm × 0.4 mm) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (ø10 mm × 7 mm) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average L*, a*, b* values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (α=.05).The average shade difference (ΔE) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. RESULTS The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ΔE value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ΔE) than th ose between the A2 composite resin and other abutments. CONCLUSION This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations. PMID:26576252

Effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations: in vitro study of color masking ability.

PubMed

Oh, Seon-Hee; Kim, Seok-Gyu

2015-10-01

The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ø10 mm × 0.4 mm) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (ø10 mm × 7 mm) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average L*, a*, b* values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (α=.05).The average shade difference (ΔE) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ΔE value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ΔE) than th ose between the A2 composite resin and other abutments. This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations.

Cytotoxicity and biocompatibility of Zirconia (Y-TZP) posts with various dental cements.

PubMed

Shin, Hyeongsoon; Ko, Hyunjung; Kim, Miri

2016-08-01

Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP) blocks in combination with several dental cements. Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE), FujiCEM 2 (GC), and Panavia F 2.0 (Kuraray) were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6) mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR), and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA). The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant. The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells. Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement.

Cytotoxicity and biocompatibility of Zirconia (Y-TZP) posts with various dental cements

PubMed Central

Shin, Hyeongsoon; Ko, Hyunjung

2016-01-01

Objectives Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP) blocks in combination with several dental cements. Materials and Methods Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE), FujiCEM 2 (GC), and Panavia F 2.0 (Kuraray) were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6) mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR), and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA). The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant. Results The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells. Conclusions Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement. PMID:27508157

Method of making a cermet fuel electrode containing an inert additive

DOEpatents

Jensen, R.R.

1992-08-25

An electrode is attached to a solid electrolyte material by: (1) mixing a metallic nickel component and 1 wt% to 10 wt% of yttria stabilized zirconia having particle diameters up to 3 micrometers with an organic binder solution to form a slurry, (2) applying the slurry to a solid zirconia electrolyte material, (3) heating the slurry to drive off the organic binder and form a porous layer of metallic nickel substantially surrounded and separated by the zirconia particles, and (4) electro-chemical vapor depositing a skeletal structure between and around the metallic nickel and the zirconia particles where the metallic nickel components do not substantially sinter to each other, yet the layer remains porous. 4 figs.

Method of making a cermet fuel electrode containing an inert additive

DOEpatents

Jensen, Russel R.

1992-01-01

An electrode is attached to a solid electrolyte material by: (1) mixing a metallic nickel component and 1 wt% to 10 wt% of yttria stabilized zirconia having particle diameters up to 3 micrometers with an organic binder solution to form a slurry, (2) applying the slurry to a solid zirconia electrolyte material, (3) heating the slurry to drive off the organic binder and form a porous layer of metallic nickel substantially surrounded and separated by the zirconia particles, and (4) electro-chemical vapor depositing a skeletal structure between and around the metallic nickel and the zirconia particles where the metallic nickel components do not substantially sinter to each other, yet the layer remains porous.

Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

PubMed Central

Li, Rui; Zhou, Hui; Wei, Wei; Wang, Chen; Sun, Ying Chun; Gao, Ping

2015-01-01

The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future. PMID:26066349

In Situ Analysis of Gas Generation in Lithium-Ion Batteries with Different Carbonate-Based Electrolytes.

PubMed

Teng, Xin; Zhan, Chun; Bai, Ying; Ma, Lu; Liu, Qi; Wu, Chuan; Wu, Feng; Yang, Yusheng; Lu, Jun; Amine, Khalil

2015-10-21

Gas generation in lithium-ion batteries is one of the critical issues limiting their safety performance and lifetime. In this work, a set of 900 mAh pouch cells were applied to systematically compare the composition of gases generated from a serial of carbonate-based composite electrolytes, using a self-designed gas analyzing system. Among electrolytes used in this work, the composite γ-butyrolactone/ethyl methyl carbonate (GBL/EMC) exhibited remarkably less gassing because of the electrochemical stability of the GBL, which makes it a promising electrolyte for battery with advanced safety and lifetime.

Cutting efficiency of diamond burs operated with electric high-speed dental handpiece on zirconia.

PubMed

Nakamura, Keisuke; Katsuda, Yusuke; Ankyu, Shuhei; Harada, Akio; Tenkumo, Taichi; Kanno, Taro; Niwano, Yoshimi; Egusa, Hiroshi; Milleding, Percy; Örtengren, Ulf

2015-10-01

Zirconia-based dental restorations are becoming used more commonly. However, limited attention has been given to the difficulties experienced, concerning cutting, in removing the restorations when needed. The aim of the present study was to compare the cutting efficiency of diamond burs, operated using an electric high-speed dental handpiece, on zirconia (Zir) with those on lithium disilicate glass-ceramic (LD) and leucite glass-ceramic (L). In addition, evaluation of the cutting efficiency of diamond burs on Zir of different thicknesses was performed. Specimens of Zir were prepared with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm, and specimens of LD and L were prepared with a thickness of 1.0 mm. Cutting tests were performed using diamond burs with super coarse (SC) and coarse (C) grains. The handpiece was operated at 150,000 rpm with a cutting force of 0.9 N. The results demonstrated that cutting of Zir took about 1.5- and 7-fold longer than cutting of LD and L, respectively. The SC grains showed significantly higher cutting efficiency on Zir than the C grains. However, when the thickness of Zir increased, the cutting depth was significantly decreased. As it is suggested that cutting of zirconia is time consuming, this should be taken into consideration in advance when working with zirconia restorations. © 2015 Eur J Oral Sci.

Polymer Electrolytes for Lithium/Sulfur Batteries

PubMed Central

Zhao, Yan; Zhang, Yongguang; Gosselink, Denise; Doan, The Nam Long; Sadhu, Mikhail; Cheang, Ho-Jae; Chen, Pu

2012-01-01

This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S) batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes. PMID:24958296

Effect of artificial aging and surface treatment on bond strengths to dental zirconia.

PubMed

Perdigão, J; Fernandes, S D; Pinto, A M; Oliveira, F A

2013-01-01

The objective of this project was to study the influence of artificial aging and surface treatment on the microtensile bond strengths (μTBS) between zirconia and a phosphate monomer-based self-adhesive cement. Thirty zirconia disks (IPS e.max ZirCAD, Ivoclar Vivadent) were randomly assigned to two aging regimens: AR, used as received, which served as a control, and AG, artificial aging to simulate low-temperature degradation. Subsequently, the disks of each aging regimen were assigned to three surface treatments: NT, no surface treatment; CO, surface silicatization with CoJet sand (3M ESPE); and ZP, zirconia surface treated with Z-Prime Plus (Bisco Inc). Thirty discs were made of Filtek Z250 (3M ESPE) composite resin and luted to the zirconia discs using RelyX Unicem (3M ESPE). The specimens were sectioned with a diamond blade in X and Y directions to obtain bonded beams with a cross-section of 1.0 ± 0.2 mm. The beams were tested in tensile mode in a universal testing machine at a speed of 0.5 mm/min to measure μTBS. Selected beams were selected for fractographic analysis under the SEM. Statistical analysis was carried out with two-way analysis of variance and Dunnett T3 post hoc test at a significance level of 95%. The mean μTBS for the three AR subgroups (AR-NT, AR-CO, and AR-ZP) were significantly higher than those of the corresponding AG groups (p<0.0001). Both AR-CO and AR-ZP resulted in statistically significant higher mean bond strengths than the group AR-NT (p<0.006 and p<0.0001, respectively). Both AG-CO and AG-ZP resulted in statistically significant higher mean bond strengths than the group AG-NT (both at p<0.0001). Overall, AG decreased mean μTBS. Under the SEM, mixed failures showed residual cement attached to the zirconia side of the beams. CO resulted in a characteristic roughness of the zirconia surface. AR-ZP was the only group for which the amount of residual cement occupied at least 50% of the interface in mixed failures.

A facile prestrain-stick-release assembly of stretchable supercapacitors based on highly stretchable and sticky hydrogel electrolyte

NASA Astrophysics Data System (ADS)

Tang, Qianqiu; Chen, Mingming; Wang, Gengchao; Bao, Hua; Saha, Petr

2015-06-01

A facile prestrain-stick-release assembly strategy for the stretchable supercapacitor device is developed based on a novel Na2SO4-aPUA/PAAM hydrogel electrolyte, saving the stretchable rubber base conventionally used. The Na2SO4-aPUA/PAAM hydrogel electrolyte exhibits high stretchability (>1000%), electrical conductivity (0.036 S cm-1) and stickiness. Due to the unique features of the hydrogel electrolyte, the carbon nanotube@MnO2 film electrodes can be firmly stuck to two sides of the prestrained hydrogel electrolyte. Then, by releasing the hydrogel electrolyte, homogenous buckles are formed for the film electrodes to get a full stretchable supercapacitor device. Besides, the high stickiness of the hydrogel electrolyte ensures its strong adhesion with the film electrodes, facilitating ion and electronic transfer of the supercapacitor. As a result, excellent electrochemical performance is achieved with the specific capacitance of 478.6 mF cm-2 at 0.5 mA cm-2 (corresponding to 201.1 F g-1) and capacitance retention of 91.5% after 3000 charging-discharging cycles under 150% strain, which is the best for the stretchable supercapacitors.

Zirconia Dental Implants: Investigation of Clinical Parameters, Patient Satisfaction, and Microbial Contamination.

PubMed

Holländer, Jens; Lorenz, Jonas; Stübinger, Stefan; Hölscher, Werner; Heidemann, Detlef; Ghanaati, Shahram; Sader, Robert

2016-01-01

In recent years, dental implants made from zirconia have been further developed and are considered a reliable treatment method for replacing missing teeth. The aim of this study was to analyze dental implants made from zirconia regarding their clinical performance compared with natural teeth (control). One hundred six zirconia implants in 38 adults were analyzed in a clinical study after 1 year of loading. The plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD), probing attachment level (PAL), and creeping or recession (CR/REC) of the gingiva were detected and compared with natural control teeth (CT). Furthermore, the papilla index (PAP), Periotest values (PTV), microbial colonization of the implant/dental sulcus fluid, and patient satisfaction were assessed. The survival rate was 100%. No statistical significance was observed between implants and teeth regarding BOP, PPD, and PAL. A statistical significance was detected regarding PI and CR/REC with significantly less plaque accumulation and recession in the study group. Mean PAP was 1.76 ± 0.55, whereas the mean PTV was -1.31 ± 2.24 (range from -5 to +6). A non-statistically significant higher colonization of periodontitis/peri-implantitis bacteria was observed in the implant group. The questionnaire showed that the majority of the patients were satisfied with the overall treatment. One-piece zirconia dental implants exhibited similar clinical results (BOP, PPD, and PAL) compared with natural teeth in regard to adhesion of plaque (PI) and creeping attachment (CR/REC); zirconia implants performed even better. The favorable results for PAL and CR/REC reflect the comparable low affinity of zirconia for plaque adhesion. Patient satisfaction indicated a high level of acceptance for zirconia implants. However, a long-term follow-up is needed to support these findings.

Grinding model and material removal mechanism of medical nanometer zirconia ceramics.

PubMed

Zhang, Dongkun; Li, Changhe; Jia, Dongzhou; Wang, Sheng; Li, Runze; Qi, Xiaoxiao

2014-01-01

Many patents have been devoted to developing medical nanometer zirconia ceramic grinding techniques that can significantly improve both workpiece surface integrity and grinding quality. Among these patents is a process for preparing ceramic dental implants with a surface for improving osseo-integration by sand abrasive finishing under a jet pressure of 1.5 bar to 8.0 bar and with a grain size of 30 µm to 250 µm. Compared with other materials, nano-zirconia ceramics exhibit unmatched biomedical performance and excellent mechanical properties as medical bone tissue and dentures. The removal mechanism of nano-zirconia materials includes brittle fracture and plastic removal. Brittle fracture involves crack formation, extension, peeling, and chipping to completely remove debris. Plastic removal is similar to chip formation in metal grinding, including rubbing, ploughing, and the formation of grinding debris. The materials are removed in shearing and chipping. During brittle fracture, the grinding-led transverse and radial extension of cracks further generate local peeling of blocks of the material. In material peeling and removal, the mechanical strength and surface quality of the workpiece are also greatly reduced because of crack extension. When grinding occurs in the plastic region, plastic removal is performed, and surface grinding does not generate grinding fissures and surface fracture, producing clinically satisfactory grinding quality. With certain grinding conditions, medical nanometer zirconia ceramics can be removed through plastic flow in ductile regime. In this study, we analyzed the critical conditions for the transfer of brittle and plastic removal in nano-zirconia ceramic grinding as well as the high-quality surface grinding of medical nanometer zirconia ceramics by ELID grinding.

Dual jaw treatment of edentulism using implant-supported monolithic zirconia fixed prostheses.

PubMed

Altarawneh, Sandra; Limmer, Bryan; Reside, Glenn J; Cooper, Lyndon

2015-01-01

This case report describes restoration of the edentulous maxilla and mandible with implant supported fixed prostheses using monolithic zirconia, where the incisal edges and occluding surfaces were made of monolithic zirconia. Edentulism is a debilitating condition that can be treated with either a removable or fixed dental prosthesis. The most common type of implant-supported fixed prosthesis is the metal acrylic (hybrid), with ceramo-metal prostheses being used less commonly in complete edentulism. However, both of these prostheses designs are associated with reported complications of screw loosening or fracture and chipping of acrylic resin and porcelain. Monolithic zirconia implant-supported fixed prostheses have the potential for reduction of such complications. In this case, the CAD/CAM concept was utilized in fabrication of maxillary and mandibular screw-retained implant-supported fixed prostheses using monolithic zirconia. Proper treatment planning and execution coupled with utilizing advanced technologies contributes to highly esthetic results. However, long-term studies are required to guarantee a satisfactory long-term outcome of this modality of treatment. This case report describes the clinical and technical procedures involved in fabrication of maxillary and mandibular implant-supported fixed prostheses using monolithic zirconia as a treatment of edentulism, and proposes the possible advantages associated with using monolithic zirconia in eliminating dissimilar interfaces in such prostheses that are accountable for the most commonly occurring technical complication for these prostheses being chipping and fracture of the veneering material. © 2015 Wiley Periodicals, Inc.

Sintering behavior and mechanical properties of zirconia compacts fabricated by uniaxial press forming

PubMed Central

Oh, Gye-Jeong; Yun, Kwi-Dug; Lee, Kwang-Min; Lim, Hyun-Pil

2010-01-01

PURPOSE The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest® ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block. PMID:21165274

Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

PubMed

Sener, Isil; Turker, Begum; Valandro, Luiz Felipe; Ozcan, Mutlu

2014-01-01

This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (α = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 μm) were significantly higher than for DC-Zircon (75.3 ± 13.2 μm) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 μm) and MDP-RC (78.5 ± 12.5 μm) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC.

Resin cementation of zirconia ceramics with different bonding agents

PubMed Central

Tanış, Merve Çakırbay; Akay, Canan; Karakış, Duygu

2015-01-01

The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations. PMID:26019653

Surface fluorination of zirconia: adhesive bond strength comparison to commercial primers.

PubMed

Piascik, Jeffrey R; Swift, Edward J; Braswell, Krista; Stoner, Brian R

2012-06-01

This study evaluated contact angle and shear bond strength of three commercial zirconia primers and compared them to a recently developed fluorination pre-treatment. Earlier investigations reported that plasma fluorinated zirconia modifies the chemical bonding structure creating a more reactive surface. Yttria-stabilized zirconia (LAVA, 3M ESPE) plates were highly polished using 3μm diamond paste (R(a) ∼200nm) prior to pretreatments. After primer and fluorination treatment, contact angles were measured to quantify surface hydrophobicity before and after ethanol clean. Additionally, simple shear bond tests were performed to measure the adhesion strength to a composite resin. Plasma fluorination produced the lowest contact angle (7.8°) and the highest shear bond strength (37.3MPa) suggesting this pretreatment facilitates a more "chemically" active surface for adhesive bonding. It is hypothesized that plasma fluorination increase hydroxylation at the surface, making it more reactive, thus allowing for covalent bonding between zirconia surface and resin cement. A strong correlation was observed between contact angle and adhesion strength for all specimens; a relationship which may help understand the frequency and modes of failures, clinically. It is also believed that this surface treatment can increase long-term viability of zirconia restorations over other adhesive techniques. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

[Effect of two-step sintering method on properties of zirconia ceramic].

PubMed

Huang, Hui; Wei, Bin; Zhang, Fu-Qiang; Sun, Jing; Gao, Lian

2008-04-01

To study the influence of two-step sintering method on the sintering property, mechanical properties and microstructure of zirconia ceramic. The nano-size zirconia powder were compacted and divided into two groups, one group for one-step sintering method, another group for two-step sintering method. All samples sintered at different temperature. The relative density, three-bend strength, HV hardness, fracture toughness and microstructure of sintered block were investigated. Two-step sintering method influenced the sintering property and mechanical properties of zirconia ceramic. The maximal relative density was 98.49% at 900 degrees C/1,450 degrees C sintering temperature. There were significant difference of mechanical properties between one-step sintering and two-step sintering, the three-bend strength and fracture toughness declined, hardness increased at two-step sintering. The three-bend strength, HV hardness and fracture toughness reached to maximum value as 1,059.08 MPa +/- 75.24 MPa, 1,377.00 MPa +/- 16.37 MPa and 5.92 MPa x m1/2 +/- 0.37 MPa x m1/2 at 900 degrees C/1,450 degrees C sintering temperature respectively. Microscopy revealed the relationship between the porosity and shapes of grains was correlated to strength of the zirconia ceramics. Despite of the two-step sintering method influences the properties of zirconia, it also is a promising esthetic all-ceramic dental material.

Photoluminescent emission of Pr 3+ ions in different zirconia crystalline forms

NASA Astrophysics Data System (ADS)

Ramos-Brito, F.; Alejo-Armenta, C.; García-Hipólito, M.; Camarillo, E.; Hernández A, J.; Murrieta S, H.; Falcony, C.

2008-08-01

Polycrystalline praseodymium doped-zirconia powders were synthesized by crystallization of a saturated solution and annealed in air at T a = 950 °C. Monoclinic, tetragonal and cubic crystalline phases of zirconia were obtained. EDS studies showed homogeneous chemical composition over all the powders particles and chemical elemental contents in good agreement with the incorporation of Pr 3+ ion in Zr 4+ sites. XRD patterns showed stabilization of tetragonal and cubic phases at 1.28 and 2.87 at.% of Pr 3+ doping concentrations, respectively. Both unit cells expand when Pr 3+ content increases. All samples showed a crystallite size lower than 27 nm. Diffuse reflectance studies exhibited the presence of the 4f5d absorption band of Pr 3+, and absorption peaks in 440-610 nm region associated with 4f inter-level electronic transitions in Pr 3+ ion. Low temperature (20 K) photo-luminescent spectroscopic measurements over excitation of 488 nm for praseodymium doped zirconia, showed multiple emission peaks in the 520-900 nm range of the electromagnetic spectrum, associated with typical 4f inter-level electronic transition in Pr 3+. Incorporation of Pr 3+ in more than one zirconia crystalline phase and the incorporation in cubic C 2 sites, were observed. Zirconia powders presented significant differences in its emission spectra as a function of the type of crystalline phase compounds.

Electrolytes with Improved Safety Developed for High Specific Energy Li-Ion Cells with Si-Based Anodes

NASA Technical Reports Server (NTRS)

Smart, M. C.; Krause, F. C.; Hwang, C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Prakash, G. K. S.

2012-01-01

A number of electrolyte formulations that have improved safety characteristics have been developed for use with high capacity silicon-based anodes. To improve the compatibility with Si-based anodes, a number of technical approaches have been employed, including: (1) the use of mono-fluoroethylene carbonate (FEC) in conjunction with, or in lieu of, ethylene carbonate (EC), (2) the use of high proportions of fluorinated co-solvents, (3) the use of vinylene carbonate (VC) to stabilize the Si/C electrode, and (4) the use of lithium bis(oxalato)borate (LiBOB) to improve the compatibility of the electrolyte when Si/C electrodes are used in conjunction with high voltage cathodes. Candidate electrolytes were studied in Li/Si-C and Si-C/ Li(MnNiCo)O2 (NMC) coin cells, as well as in larger Si-C/NMC three-electrode cells equipped with lithium reference electrodes. In summary, many electrolytes that contain triphenyl phosphate (TPP), which is used as a flame retardant additive up to concentrations of 15 volume percent, and possess FEC as a co-solvent have been demonstrated to outperform the all-carbonate baseline electrolytes when evaluated in Si-C/ Li(MnNiCo)O2 cells.

Structure and properties of solid polymer electrolyte based on chitosan and ZrO{sub 2} nanoparticle for lithium ion battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudaryanto,, E-mail: dryanto@batan.go.id; Yulianti, Evi, E-mail: yulianti@batan.go.id; Patimatuzzohrah, E-mail: pzohrah@yahoo.com

In order to develop all solid lithium ion battery, study on the structure and properties of solid polymer electrolytes (SPE) based on chitosan has been done. The SPE were prepared by adding Zirconia (ZrO{sub 2}) nanoparticle and LiClO{sub 4} as lithium salt into the chitosan solution followed by casting method. Effect of the ZrO{sub 2} and salt concentration to the structure and properties of SPE were elaborated using several methods. The structure of the SPE cast film, were characterized mainly by using X-ray diffractometer (XRD). While the electrical properties of SPE were studied by electrochemical impedance spectrometer (EIS) and ionmore » transference number measurement. XRD profiles show that the addition of ZrO{sub 2} and LiClO{sub 4} disrupts the crystality of chitosan. The decrease in sample crytalinity with the nanoparticle and salt addition may increase the molecular mobility result in the increasing sample conductivity and cathionic transference number as determined by EIS and ion transference number measurement, respectively. The highest ionic conductivity (3.58×10{sup −4} S cm{sup −1}) was obtained when 4 wt% of ZrO{sub 2} nanoparticle and 40 wt% of LiClO{sub 4} salt were added to the chitosan. The ion transference number with that composition was 0.55. It is high enough to be used as SPE for lithium ion battery.« less

Loading capacity of zirconia implant supported hybrid ceramic crowns.

PubMed

Rohr, Nadja; Coldea, Andrea; Zitzmann, Nicola U; Fischer, Jens

2015-12-01

Recently a polymer infiltrated hybrid ceramic was developed, which is characterized by a low elastic modulus and therefore may be considered as potential material for implant supported single crowns. The purpose of the study was to evaluate the loading capacity of hybrid ceramic single crowns on one-piece zirconia implants with respect to the cement type. Fracture load tests were performed on standardized molar crowns milled from hybrid ceramic or feldspar ceramic, cemented to zirconia implants with either machined or etched intaglio surface using four different resin composite cements. Flexure strength, elastic modulus, indirect tensile strength and compressive strength of the cements were measured. Statistical analysis was performed using two-way ANOVA (p=0.05). The hybrid ceramic exhibited statistically significant higher fracture load values than the feldspar ceramic. Fracture load values and compressive strength values of the respective cements were correlated. Highest fracture load values were achieved with an adhesive cement (1253±148N). Etching of the intaglio surface did not improve the fracture load. Loading capacity of hybrid ceramic single crowns on one-piece zirconia implants is superior to that of feldspar ceramic. To achieve maximal loading capacity for permanent cementation of full-ceramic restorations on zirconia implants, self-adhesive or adhesive cements with a high compressive strength should be used. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of surface treatment on the in-vitro fracture resistance of zirconia-based all-ceramic anterior crowns.

PubMed

Schmitter, M; Lotze, G; Bömicke, W; Rues, S

2015-12-01

The purpose of this study was to assess the effect of surface treatment on the fracture resistance of zirconia-based all-ceramic anterior crowns. Sixty-four zirconia-based all-ceramic anterior crowns, veneered by use of a press-on technique, were produced. For 48 crowns intraoral adjustment was simulated (A-group), 16 crowns remained unadjusted (WA-group). The adjusted area was then treated in three ways: 1. no further surface treatment; 2. polishing, with irrigation, using polishers interspersed with diamond grit for ceramics; and 3. polishing and glaze firing. Half of the specimens were loaded until fracture in an universal testing device without artificial ageing; the other crowns underwent thermocycling and chewing simulation before ultimate-load testing. Explorative statistical analysis was performed by use of non-parametric and parametric tests. In addition, fracture-strength tests according to ISO 6872 were performed for veneer ceramic subjected to the different surface treatments. Finite element analysis was also conducted for the crowns, and surface roughness was measured. Crowns in the A-group were more sensitive to aging than crowns in the WA-group (p=0.038). Although both polishing and glaze firing slightly improved the fracture resistance of the specimens, the fracture resistance in the WA-group (initial fracture resistance (IFR): 652.0 ± 107.7N, remaining fracture resistance after aging (RFR): 560.6 ± 233.3N) was higher than the fracture resistance in the A-group (polished: IFR: 477.9 ± 108.8N, RFR: 386.0 ± 218.5N; glaze firing: IFR: 535.5 ± 128.0N, RFR: 388.6 ± 202.2N). Surface roughness without adjustment was Ra=0.1 μm; for adjustment but without further treatment it was Ra=1.4 μm; for adjustment and polishing it was Ra=0.3 μm; and for adjustment, polishing, and glazing it was Ra=0.6 μm. Stress distributions obtained by finite element analysis in combination with fracture strength tests showed that fractures most probably originated from

Porous zirconia ceramic as an alternative to dentin for in vitro dentin barriers cytotoxicity test.

PubMed

Hu, Meng-Long; Lin, Hong; Jiang, Ruo-Dan; Dong, Li-Min; Huang, Lin; Zheng, Gang

2018-06-01

This study assessed the potential of porous zirconia ceramic as an alternative to dentin via an in vitro dentin barrier cytotoxicity test. The permeability of dentin and porous zirconia ceramic was measured using a hydraulic-conductance system, and their permeability was divided into two groups: high and low. Using an in vitro dentin barrier test, the cytotoxicity of dental materials by dentin and porous zirconia ceramic was compared within the same permeability group. The L-929 cell viability was assessed by MTT assay. The mean (SD) permeability of the high and low group for dentin was 0.334 (0.0873) and 0.147 (0.0377) μl min -1  cm -2  cm H 2 O -1 and for zirconia porous ceramic was 0.336 (0.0609) and 0.146 (0.0340) μl min -1  cm -2  cm H 2 O -1 . The cell viability of experimental groups which are the low permeability group was higher than that of the high permeability group for both dentin and porous zirconia ceramic as a barrier except for Maxcem Elite ™ by porous zirconia ceramic. There was no significant difference between dentin and porous zirconia ceramic in cell viability, within either the high or low permeability group for all materials. The SD for cell viability of the porous zirconia ceramic was less than that of the dentin, across all materials within each permeability group, except for Maxcem Elite ™ in the high permeability group. Porous zirconia ceramic, having similar permeability to dentin at the same thickness, can be used as an alternative to dentin for in vitro dentin barrier cytotoxicity tests. In vitro dentin barrier cytotoxicity tests when a standardized porous zirconia ceramic was used as a barrier could be useful for assessing the potential toxicity of new dental materials applied to dentin before applying in clinical and may resolve the issue of procuring human teeth when testing proceeds.

Randomized clinical study of wear of enamel antagonists against polished monolithic zirconia crowns

PubMed Central

Esquivel-Upshaw, J.F.; Kim, M.J.; Hsu, S.M.; Abdulhameed, N.; Jenkins, R.; Neal, D.; Ren, F.; Clark, A.E.

2018-01-01

Objectives To test the hypothesis that there is no difference in the in vivo maximum wear of enamel opposing monolithic zirconia crowns, enamel opposing porcelain fused to metal crowns and enamel opposing enamel. Methods Thirty patients needing single crowns were randomized to receive either a monolithic zirconia or metal-ceramic crown. Two non-restored opposing teeth in the same quadrants were identified to serve as enamel controls. After cementation, quadrants were scanned for baseline data. Polyvinylsiloxane impressions were obtained and poured in white stone. Patients were recalled at six-months and one-year for re-impression. Stone models were scanned using a tabletop laserscanner to determine maximum wear. Statistical analysis was performed using Mann-Whitney U to determine any significant differences between the wear of enamel against zirconia and metal-ceramic crowns. Results Sixteen zirconia and 14 metal-ceramic crowns were delivered. There were no statistical differences in mean wear of crown types (p = 0.165); enamel antagonists (p = 0.235) and enamel controls (p = 0.843) after one year. Conclusion Monolithic zirconia exhibited comparable wear of enamel compared with metal-ceramic crowns and control enamel after one year. Significance This study is clinically significant because the use of polished monolithic zirconia demonstrated comparable wear of opposing enamel to metal-ceramic and enamel antagonists. PMID:29042241

Randomized trial investigating zirconia electroplated telescopic retainers: quality of life outcomes.

PubMed

Schwindling, Franz Sebastian; Deisenhofer, Ulrich Karl; Séché, Anne-Christiane; Lehmann, Franziska; Rammelsberg, Peter; Stober, Thomas

2017-05-01

The study aims to evaluate the effect of electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns on oral-health-related quality of life (OHRQoL). For E-RDPs, electroplating is used to produce precisely fitting gold copings on telescopic primary crowns. These copings are bonded intra-orally to the denture framework. Fifty-six participants in need of 60 removable restorations were randomly allocated one of two materials for the primary crowns: cobalt-chromium alloy or zirconia. OHRQoL was assessed by use of the 49-item Oral Health Impact Profile (OHIP-49) and by additional patient self-rating at baseline before treatment, and after 6 and 12 months. Statistical analysis was performed by use of one- and two-sample t-tests and analysis of covariance. Mean OHIP sum score at baseline was 53.4 (SD 37.4, 95 % CI 41.3-62). At follow-ups, it decreased significantly (after 6 months: mean 20, SD 26, 95 % CI 13-27.1; after 12 months: mean 16.4, SD 17.9, 95 % CI 11.6-21.2). The mean reduction in OHIP sum score after 12 months was 25 (SD 31.2, 95 % CI 13.1-36.9) for cobalt-chromium alloy and 44.4 (SD 32.3, 95 % CI 31.1-57.8) for zirconia. However, no statistically significant difference of the two materials on OHIP change or patient self-rating was detected. Although OHRQoL was improved by using both cobalt-chromium alloy and zirconia primary crowns for E-RDPs, post-treatment differences between the groups were not statistically significant. Zirconia E-RDPs enhance OHRQoL. However, zirconia primary crowns do not outperform cobalt-chromium alloy crowns regarding patient satisfaction-despite their tooth-like color.

Electrolyte diodes with weak acids and bases. I. Theory and an approximate analytical solution.

PubMed

Iván, Kristóf; Simon, Péter L; Wittmann, Mária; Noszticzius, Zoltán

2005-10-22

Until now acid-base diodes and transistors applied strong mineral acids and bases exclusively. In this work properties of electrolyte diodes with weak electrolytes are studied and compared with those of diodes with strong ones to show the advantages of weak acids and bases in these applications. The theoretical model is a one dimensional piece of gel containing fixed ionizable groups and connecting reservoirs of an acid and a base. The electric current flowing through the gel is measured as a function of the applied voltage. The steady-state current-voltage characteristic (CVC) of such a gel looks like that of a diode under these conditions. Results of our theoretical, numerical, and experimental investigations are reported in two parts. In this first, theoretical part governing equations necessary to calculate the steady-state CVC of a reverse-biased electrolyte diode are presented together with an approximate analytical solution of this reaction-diffusion-ionic migration problem. The applied approximations are quasielectroneutrality and quasiequilibrium. It is shown that the gel can be divided into an alkaline and an acidic zone separated by a middle weakly acidic region. As a further approximation it is assumed that the ionization of the fixed acidic groups is complete in the alkaline zone and that it is completely suppressed in the acidic one. The general solution given here describes the CVC and the potential and ionic concentration profiles of diodes applying either strong or weak electrolytes. It is proven that previous formulas valid for a strong acid-strong base diode can be regarded as a special case of the more general formulas presented here.

Synthesis and characterization of scandia ceria stabilized zirconia powders prepared by polymeric precursor method for integration into anode-supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Tu, Hengyong; Liu, Xin; Yu, Qingchun

2011-03-01

Scandia ceria stabilized zirconia (10Sc1CeSZ) powders are synthesized by polymeric precursor method for use as the electrolyte of anode-supported solid oxide fuel cell (SOFC). The synthesized powders are characterized in terms of crystalline structure, particle shape and size distribution by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). 10Sc1CeSZ electrolyte films are deposited on green anode substrate by screen-printing method. Effects of 10Sc1CeSZ powder characteristics on sintered films are investigated regarding the integration process for application as the electrolytes in anode-supported SOFCs. It is found that the 10Sc1CeSZ films made from nano-sized powders with average size of 655 nm are very porous with many open pores. In comparison, the 10Sc1CeSZ films made from micron-sized powders with average size of 2.5 μm, which are obtained by calcination of nano-sized powders at higher temperatures, are much denser with a few closed pinholes. The cell performances are 911 mW cm-2 at the current density of 1.25 A cm-2 and 800 °C by application of Ce0.8Gd0.2O2 (CGO) barrier layer and La0.6Sr0.4CoO3 (LSC) cathode.

Marginal accuracy of computer-aided design- and computer-aided manufacturing-fabricated full-arch zirconia restoration

PubMed Central

Sirisathit, Issarawas

2018-01-01

Objective This study evaluated marginal accuracy of full-arch zirconia restoration fabricated from two digital computer-aided design and computer-aided manufacturing (CAD-CAM) systems (Trios-3 and CS3500) in comparison to conventional cast metal restoration. Materials and methods A stainless steel model comprising two canine and two molar abutments was used as a master model for full-arch reconstruction. The canine and molar abutments were machined in a cylindrical shape with 5° taper and chamfer margin. The CAD-CAM systems based on the digital approach were used to construct the full-arch zirconia restoration. The conventional cast metal restoration was fabricated according to a conventional lost-wax technique using nickel–chromium alloys. Ten restorations were fabricated from each system. The marginal accuracy of each restoration was determined at four locations for each abutment. An analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) multiple comparisons were used to determine statistically significant difference at 95% confidence interval. Results The mean values of marginal accuracy of restorations fabricated from conventional casting, Trios-3, and CS3500 were 48.59±4.16 μm, 53.50±5.66 μm, and 56.47±5.52 μm, respectively. ANOVA indicated significant difference in marginal fit of restorations among various systems. The marginal discrepancy of zirconia restoration fabricated from the CS3500 system demonstrated significantly larger gap than that fabricated from the 3Shape system (p<0.05). Tukey’s HSD multiple comparisons indicated that the zirconia restoration fabricated from either CS3500 or Trios-3 demonstrated a significantly larger marginal gap than the conventional cast metal restoration (p<0.05). Conclusion Full-arch zirconia restoration fabricated from the Trios-3 illustrated better marginal fits than that from the CS3500, although, both were slightly less accurate than the conventional cast restoration. However, the

Marginal accuracy of computer-aided design- and computer-aided manufacturing-fabricated full-arch zirconia restoration.

PubMed

Juntavee, Niwut; Sirisathit, Issarawas

2018-01-01

This study evaluated marginal accuracy of full-arch zirconia restoration fabricated from two digital computer-aided design and computer-aided manufacturing (CAD-CAM) systems (Trios-3 and CS3500) in comparison to conventional cast metal restoration. A stainless steel model comprising two canine and two molar abutments was used as a master model for full-arch reconstruction. The canine and molar abutments were machined in a cylindrical shape with 5° taper and chamfer margin. The CAD-CAM systems based on the digital approach were used to construct the full-arch zirconia restoration. The conventional cast metal restoration was fabricated according to a conventional lost-wax technique using nickel-chromium alloys. Ten restorations were fabricated from each system. The marginal accuracy of each restoration was determined at four locations for each abutment. An analysis of variance (ANOVA) and Tukey's honest significant difference (HSD) multiple comparisons were used to determine statistically significant difference at 95% confidence interval. The mean values of marginal accuracy of restorations fabricated from conventional casting, Trios-3, and CS3500 were 48.59±4.16 μm, 53.50±5.66 μm, and 56.47±5.52 μm, respectively. ANOVA indicated significant difference in marginal fit of restorations among various systems. The marginal discrepancy of zirconia restoration fabricated from the CS3500 system demonstrated significantly larger gap than that fabricated from the 3Shape system ( p <0.05). Tukey's HSD multiple comparisons indicated that the zirconia restoration fabricated from either CS3500 or Trios-3 demonstrated a significantly larger marginal gap than the conventional cast metal restoration ( p <0.05). Full-arch zirconia restoration fabricated from the Trios-3 illustrated better marginal fits than that from the CS3500, although, both were slightly less accurate than the conventional cast restoration. However, the marginal discrepancies of restoration produced by both

Towards A Model-Based Prognostics Methodology for Electrolytic Capacitors: A Case Study Based on Electrical Overstress Accelerated Aging

NASA Technical Reports Server (NTRS)

Celaya, Jose R.; Kulkarni, Chetan S.; Biswas, Gautam; Goebel, Kai

2012-01-01

A remaining useful life prediction methodology for electrolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated aging test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation progression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognostics methods typically used for remaining useful life predictions in other applications.

Energy-density enhancement of carbon-nanotube-based supercapacitors with redox couple in organic electrolyte.

PubMed

Park, Jinwoo; Kim, Byungwoo; Yoo, Young-Eun; Chung, Haegeun; Kim, Woong

2014-11-26

We demonstrate for the first time that the incorporation of a redox-active molecule in an organic electrolyte can increase the cell voltage of a supercapacitor. The redox molecule also contributes to increasing the cell capacitance by a faradaic redox reaction, and therefore the energy density of the supercapacitor can be significantly increased. More specifically, the addition of redox-active decamethylferrocene in an organic electrolyte results in an approximately 27-fold increase in the energy density of carbon-nanotube-based supercapacitors. The resulting high energy density (36.8 Wh/kg) stems from the increased cell voltage (1.1 V→2.1 V) and cell capacitance (8.3 F/g→61.3 F/g) resulting from decamethylferrocene addition. We found that the voltage increase is associated with the potential of the redox species relative to the electrochemical stability window of the supporting electrolyte. These results will be useful in identifying new electrolytes for high-energy-density supercapacitors.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes

NASA Astrophysics Data System (ADS)

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-01

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ˜75 F g-1, ˜987 kW kg-1 and ˜27 W h kg-1, respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (˜158 F g-1) and energy density (˜53 W h kg-1). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices.

High-performance supercapacitors based on vertically aligned carbon nanotubes and nonaqueous electrolytes.

PubMed

Kim, Byungwoo; Chung, Haegeun; Kim, Woong

2012-04-20

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were ~75 F g(-1), ~987 kW kg(-1) and ~27 W h kg(-1), respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2 s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (~158 F g(-1)) and energy density (~53 W h kg(-1)). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube- and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices. © 2012 IOP Publishing Ltd

In vivo evaluation of zirconia ceramic in the DexAide right ventricular assist device journal bearing.

PubMed

Saeed, Diyar; Shalli, Shanaz; Fumoto, Hideyuki; Ootaki, Yoshio; Horai, Tetsuya; Anzai, Tomohiro; Zahr, Roula; Horvath, David J; Massiello, Alex L; Chen, Ji-Feng; Dessoffy, Raymond; Catanese, Jacquelyn; Benefit, Stephen; Golding, Leonard A R; Fukamachi, Kiyotaka

2010-06-01

Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14-91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device-induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

NASA Astrophysics Data System (ADS)

Ward, Antony J.; Pujari, Ajit A.; Costanzo, Lorenzo; Masters, Anthony F.; Maschmeyer, Thomas

2011-12-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%.

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

PubMed Central

2011-01-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%. PMID:21711725

Sol-gel derived bioactive coating on zirconia: Effect on flexural strength and cell proliferation.

PubMed

Shahramian, Khalil; Leminen, Heidi; Meretoja, Ville; Linderbäck, Paula; Kangasniemi, Ilkka; Lassila, Lippo; Abdulmajeed, Aous; Närhi, Timo

2017-11-01

The purpose of this study was to evaluate the effect of sol-gel derived bioactive coatings on the biaxial flexural strength and fibroblast proliferation of zirconia, aimed to be used as an implant abutment material. Yttrium stabilized zirconia disc-shaped specimens were cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n = 15) were fabricated, zirconia with sol-gel derived titania (TiO 2 ) coating, zirconia with sol-gel derived zirconia (ZrO 2 ) coating, and non-coated zirconia as a control. The surfaces of the specimens were analyzed through images taken using a scanning electron microscope (SEM), and a non-contact tapping mode atomic force microscope (AFM) was used to record the surface topography and roughness of the coated specimens. Biaxial flexural strength values were determined using the piston-on-three ball technique. Human gingival fibroblast proliferation on the surface of the specimens was evaluated using AlamarBlue assay™. Data were analyzed using a one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Additionally, the biaxial flexural strength data was also statistically analyzed with the Weibull distribution. The biaxial flexural strength of zirconia specimens was unaffected (p > 0.05). Weibull modulus of TiO 2 coated and ZrO 2 coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO 2 showed significantly lower fibroblast proliferation compared to other groups (p < 0.05). In conclusion, sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO 2 coated specimens showed significantly lower cell proliferation after 12 days than TiO 2 coated or non-coated control. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2401-2407, 2017. © 2016 Wiley Periodicals, Inc.

Zirconia-molybdenum disilicide composites

DOEpatents

Petrovic, John J.; Honnell, Richard E.

1991-01-01

Compositions of matter comprised of molybdenum disilicide and zirconium oxide in one of three forms: pure, partially stabilized, or fully stabilized and methods of making the compositions. The stabilized zirconia is crystallographically stabilized by mixing it with yttrium oxide, calcium oxide, cerium oxide, or magnesium oxide and it may be partially stabilized or fully stabilized depending on the amount of stabilizing agent in the mixture.

Fracture resistance of inter-joined zirconia abutment of dental implant system with injection molding technique.

PubMed

Yang, Jianjun; Wang, Ke; Liu, Guangyuan; Wang, Dashan

2013-11-01

Zirconia powder in nanometers can be fabricated into inter-joined abutment of dental implant system with the injection shaping technique. This study was to detect the resistance of inter-joined zirconia abutment with different angle loading for clinical applications. The inter-joined abutments were shaped with the technique of injection of zirconia powder in nanometers. Sixty Osstem GSII 5 × 10 mm implants were used with 30 zirconia abutments and 30 Osstem GSII titanium abutments for fixation using 40 N torque force. The loading applications included 90°, 30°, and 0° formed by the long axis of abutments and pressure head of universal test machine. The fracture resistances of zirconia and titanium abutments were documented and analyzed. The inter-joined zirconia abutments were assembled to the Osstem GSII implants successfully. In the 90° loading mode, the fracture resistance of zirconia abutment group and titanium abutment group were 301.5 ± 15.4 N and 736.4 ± 120.1 N, respectively. And those in the 30° groups were 434.7 ± 36.1 N and 1073.1 ± 74 N, correspondingly. Significant difference in the two groups was found using t-test and Wilcoxon test. No damage on the abutments of the two groups but S-shaped bending on the implants was found when the 0° loading was 1300-2000 N. Through the assembly of Zirconia abutments and implants, all the components presented sufficient resistance acquired for the clinical application under loadings with different angle. © 2012 John Wiley & Sons A/S.

Adsorption of dispersants on zirconia powder in tape-casting slip compositions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richards, V.L. II

This paper reports the determination of adsorption isotherms for menhaden fish oil and glycerol trioleate on doped zirconia powder in solvents composed of 70% methyl ethyl ketone (MEK) and 30% ethanol. In order to approach tape-casting zirconia on a sound technical basis, the correspondence of slip viscosities and tape sintered densities to the adsorption isotherms was studied.

Developing porous ceramics on the base of zirconia oxide with thin and permeable pores by crystallization of organic additive method

NASA Astrophysics Data System (ADS)

Kamyshnaya, K. S.; Khabas, T. A.

2016-11-01

In this paper porous ceramics on the base of ZrO2 nanopowders and micropowders has been developed by freeze-casting method. A zirconia/carbamide slurry was frozen in mold and dehydrated in CaCl2 at room temperature. This simple process enabled the formation of porous ceramics with highly aligned pores as a replica of the carbamide crystals. The samples showed higher porosity of 47.9%. In addition, these materials could be used as membrane for air cleaning.

Effect of Three Different Core Materials on Masking Ability of a Zirconia Ceramic.

PubMed

Tabatabaian, Farhad; Masoomi, Faeze; Namdari, Mahshid; Mahshid, Minoo

2016-09-01

Masking ability of a restorative material plays a role in hiding colored substructures; however, the masking ability of zirconia ceramic (ZRC) has not yet been clearly understood in zirconia-based restorations. This study evaluated the effect of three different core materials on masking ability of a ZRC. Ten zirconia disc samples, 0.5mm in thickness and 10mm in diameter, were fabricated. A white (W) substrate (control) and three substrates of nickel-chromium alloy (NCA), non-precious gold alloy (NPGA), and ZRC were prepared. The zirconia discs were placed on the four types of substrates for spectrophotometry. The L*, a*, and b* values of the specimens were measured by a spectrophotometer and color change (ΔE) values were calculated to determine color differences between the test and control groups and were then compared with the perceptual threshold. Randomized block ANOVA and Bonferroni test analyzed the data. A significance level of 0.05 was considered. The mean and standard deviation values of ΔE for NCA, NPGA, and ZRC groups were 10.26±2.43, 9.45±1.74, and 6.70±1.91 units, respectively. Significant differences were found in the ΔE values between ZRC and the other two experimental groups (NCA and NPGA; P<0.0001 and P=0.001, respectively). The ΔE values for the groups were more than the predetermined perceptual threshold. Within the limitations of this study, it was concluded that the tested ZRC could not well mask the examined core materials.

Tribochemical Glass Ceramic Coating as a New Approach for Resin Adhesion to Zirconia.

PubMed

Wandscher, Vinícius Felipe; Fraga, Sara; Pozzobon, João Luiz; Soares, Fabio Zovico Maxnuck; Foletto, Edson Luiz; May, Liliana Gressler; Valandro, Luiz Felipe

To investigate the effects of a novel tribochemical silica coating technique with powders made from feldspathic ceramic and leucite-based ceramic on the bond strength of zirconia to resin cement before and after aging. Zirconia blocks were divided into 3 groups according to the material used for airborne-particle abrasion: 1) SP (control): silica-coated alumina particles; 2) FP: feldspathic ceramic powder; 3) LP: leucite glass-ceramic powder. After silanization, composite resin cylinders were cemented on the zirconia surface using a dual-curing resin cement. Prior to the shear bond strength (SBS) test, half of the samples (n = 15) were stored in distilled water for 24 h; the other half (n = 15) were submitted to aging (10,000 thermocycles of 5°C to 55°C; 150 days of water storage). The bond strength data were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction analysis were performed. The initial bond strengths did not differ significantly between the groups (p = 0.053). However, after aging procedures, airborne-particle abrasion with feldspathic ceramic powder (FP) resulted in higher values of bond strength (p = 0.0001). SEM and EDS indicated that all the treatments promoted silica deposition on the Y-TZP surface ceramic. Airborne-particle abrasion with FP and LP induced a lower percentage of the monoclinic phase. Airborne abrasion with fine feldspathic ceramic particles is a novel tribochemical technique and appears to be suitable for improving the bond strength between zirconia and resin cements.

Role of perfluoropolyether-based electrolytes in lithium metal batteries: Implication for suppressed Al current collector corrosion and the stability of Li metal/electrolytes interfaces

NASA Astrophysics Data System (ADS)

Cong, Lina; Liu, Jia; Armand, Michel; Mauger, Alain; Julien, Christian M.; Xie, Haiming; Sun, Liqun

2018-03-01

The development of safe and high performance lithium metal batteries represents a major technological challenge for this new century. Historically, intrinsic instabilities of conventional liquid organic electrolytes induced battery failures and safety issues that hinder the practical utilization of advanced rechargeable lithium metal batteries. Herein, we report a multifunctional perfluoropolyether-based liquid polymer electrolyte (PFPE-MC/LiTFSI), presenting a unique "anion-solvent" interaction. This interaction optimizes the interfacial chemistry of lithium metal batteries, which effectively inhibits the corrosion of aluminum current collectors, suppresses lithium dendrite growth, and also facilitates the formation of a thin and stable SEI layer on Li anode. Even at a high current density of 0.7 mA cm-2, the lithium dendrites do not form after 1360 h of continuous operation. The LiFePO4|PFPE-MC/LiTFSI|Li cell delivers a stable cycling performance with over 99.9% columbic efficiency either at ambient temperature or high temperature, which is significantly superior to those using traditional carbonate electrolytes. In addition, PFPE-MC/LiTFSI electrolyte also possesses eye-catching properties, such as being non-flammable, non-volatile, non-hygroscopic, and existing in the liquid state between -90 °C and 200 °C, which further ensures the high safety of the lithium metal batteries, making this electrolyte promising for the development of high energy lithium metal batteries.

Twin and habit plane microstructures due to the tetragonal to monoclinic transformation of zirconia

NASA Astrophysics Data System (ADS)

Simha, N. K.

1997-02-01

We first construct Bain strains for the tetragonal to monoclinic ( t → m) transformation of zirconia (ZrO 2), and then examine the resulting twin and habit plane microstructures. The ( t → m) transformation in zirconia occurs via two paths; transformation along path I has two Bain strains that involve shearing of a rectangular face of the tetragonal unit cell, and shearing of the square base corresponds to path II. The monoclinic variants resulting from each of the three Bain strains can form 12 twins, and four of the twins corresponding to path II are neither of type I nor of type II. Habit planes do not exist for the transformation along path I, whereas transformation along path II has: (± 0.8139, ± 0.3898, - 0.4309) t, (± 0.6489, ± 0.6271, - 0.4309) t, (± 0.7804, ± 0.4530, - 0.4309) t. We predict the exact twin planes observed by Bailey [(1964) Phase transformation at high temperatures in hafnia and zirconia. Proc. Roy. Soc.279A, 395-412], Bansal and Heuer [(1972) On a martensitic phase transformation in Zirconia ZrO 2—I. Metallographic evidence. Acta Metall.20, 1281-1289] and Buljan et al. [(1976) Optical and X-ray single crystal studies of the monoclinic ↔ tetragonal transition in ZrO 2. J. Am. Ceram. Soc.59, 351-354]; additional twins and habit planes that we predict have not yet been observed.

[Effect of compaction pressure on the properties of dental machinable zirconia ceramic].

PubMed

Huang, Hui; Wei, Bin; Zhang, Fu-qiang; Sun, Jing; Gao, Lian

2010-10-01

To investigate the effect of compaction pressure on the linear shrinkage, sintering property and machinability of the dental zirconia ceramic. The nano-size zirconia powder was compacted at different isostatic pressure and sintered at different temperature. The linear shrinkage of sintered body was measured and the relative density was tested using the Archimedes method. The cylindrical surface of pre-sintering blanks was traversed using a hard metal tool. Surface and edge quality were checked visually using light stereo microscopy. The sintering behaviour depended on the compaction pressure. Increasing compaction pressure led to higher sintering rate and lower sintering temperature. Increasing compaction pressure also led to decreasing linear shrinkage of the sintered bodies, from 24.54% of 50 MPa to 20.9% of 400 MPa. Compaction pressure showed only a weak influence on machinability of zirconia blanks, but the higher compaction pressure resulted in the poor surface quality. The better sintering property and machinability of dental zirconia ceramic is found for 200-300 MPa compaction pressure.

Silicon carbide whisker-zirconia reinforced mullite and alumina ceramics

DOEpatents

Becher, Paul F.; Tiegs, Terry N.

1987-01-01

The flexural strength and/or fracture toughness of SiC whisker-reinforced composites utilizing mullite or alumina as the matrix material for the composite are increased by the addition of zirconia in a monoclinic or tetragonal phase to the matrix. The zirconia addition also provides for a lower hot-pressing temperature and increases the flexural strength and/or fracture toughness of the SiC whisker-reinforced composites over SiC whisker-reinforced composites of the similar matrix materials reinforced with similar concentrations of SiC whiskers.

Photocatalytic performance of freestanding tetragonal zirconia nanotubes formed in H2O2/NH4F/ethylene glycol electrolyte by anodisation of zirconium

NASA Astrophysics Data System (ADS)

Rozana, Monna; Izza Soaid, Nurul; Kian, Tan Wai; Kawamura, Go; Matsuda, Atsunori; Lockman, Zainovia

2017-04-01

ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glycol electrolyte. The as-anodised foils were then soaked in the anodising electrolyte for 12 h. Soaking weakens the adherence of the anodic layer from the substrate resulting in freestanding ZrNTs (FS-ZrNTs). Moreover, the presence of H2O2 in the electrolyte also aids in weakening the adhesion of the film from the foil, as foil anodised in electrolyte without H2O2 has good film adherence. The as-anodised FS-ZrNTs film was amorphous and crystallised to predominantly tetragonal phase upon annealing at >300 °C. Annealing must, however, be done at <500 °C to avoid monoclinic ZrO2 formation and nanotubes disintegration. FS-ZrNTs annealed at 450 °C exhibited the highest photocatalytic ability to degrade methyl orange (MO), whereby 82% MO degradation was observed after 5 h, whereas FS-ZrNTs with a mixture of monoclinic and tetragonal degraded 70% of MO after 5 h.

Synthesis and Characterization of Cellulose-Based Hydrogels to Be Used as Gel Electrolytes

PubMed Central

Navarra, Maria Assunta; Dal Bosco, Chiara; Serra Moreno, Judith; Vitucci, Francesco Maria; Paolone, Annalisa; Panero, Stefania

2015-01-01

Cellulose-based hydrogels, obtained by tuned, low-cost synthetic routes, are proposed as convenient gel electrolyte membranes. Hydrogels have been prepared from different types of cellulose by optimized solubilization and crosslinking steps. The obtained gel membranes have been characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical tests in order to investigate the crosslinking occurrence and modifications of cellulose resulting from the synthetic process, morphology of the hydrogels, their thermal stability, and viscoelastic-extensional properties, respectively. Hydrogels liquid uptake capability and ionic conductivity, derived from absorption of aqueous electrolytic solutions, have been evaluated, to assess the successful applicability of the proposed membranes as gel electrolytes for electrochemical devices. To this purpose, the redox behavior of electroactive species entrapped into the hydrogels has been investigated by cyclic voltammetry tests, revealing very high reversibility and ion diffusivity. PMID:26633528

Study of Laser Drilled Hole Quality of Yttria Stabilized Zirconia

NASA Astrophysics Data System (ADS)

Saini, Surendra K.; Dubey, Avanish K.; Pant, Piyush; Upadhyay, B. N.; Choubey, A.

2017-09-01

The Yttria Stabilized Zirconia ceramic is extensively used in aerospace, automotives, medical and microelectronics industries. These applications demand manufacturing of different macro and micro features with close tolerances in this material. To make miniature holes with accurate dimensions in advanced ceramics such as Yttria Stabilized Zirconia is very difficult due to its tailored attributes such as high toughness, hardness, strength, resistance to wear, corrosion and temperature. Due to inherent characteristics of laser drilling, researchers are working to fulfill the requirement of creation of micro holes in advanced ceramics. The present research investigates the laser drilling of 2 mm thick Yttria Stabilized Zirconia with the aim to achieve good micro holes with reduced geometrical inaccuracies and improved hole quality. The results show that multiple quality response comprising hole circularity, hole taper and recast layer thickness has been improved at optimally selected process parameters.

[Study on friction and wear properties of dental zirconia ceramics processed by microwave and conventional sintering methods].

PubMed

Guoxin, Hu; Ying, Yang; Yuemei, Jiang; Wenjing, Xia

2017-04-01

This study evaluated the wear of an antagonist and friction and wear properties of dental zirconia ceramic that was subjected to microwave and conventional sintering methods. Ten specimens were fabricated from Lava brand zirconia and randomly assigned to microwave and conventional sintering groups. A profile tester for surface roughness was used to measure roughness of the specimens. Wear test was performed, and steatite ceramic was used as antagonist. Friction coefficient curves were recorded, and wear volume were calculated. Finally, optical microscope was used to observe the surface morphology of zirconia and steatite ceramics. Field emission scanning electron microscopy was used to observe the microstructure of zirconia. Wear volumes of microwave and conventionally sintered zirconia were (6.940±1.382)×10⁻², (7.952±1.815) ×10⁻² mm³, respectively. Moreover, wear volumes of antagonist after sintering by the considered methods were (14.189±4.745)×10⁻², (15.813±3.481)×10⁻² mm³, correspondingly. Statistically significant difference was not observed in the wear resistance of zirconia and wear volume of steatite ceramic upon exposure to two kinds of sintering methods. Optical microscopy showed that ploughed surfaces were apparent in zirconia. The wear surface of steatite ceramic against had craze, accompanied by plough. Scanning electron microscopy showed that zirconia was sintered compactly when subjected to both conventional sintering and microwave methods, whereas grains of zirconia sintered by microwave alone were smaller and more uniform. Two kinds of sintering methods are successfully used to produce dental zirconia ceramics with similar friction and wear properties.
.

Outstanding features of alginate-based gel electrolyte with ionic liquid for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Soeda, Kazunari; Yamagata, Masaki; Ishikawa, Masashi

2015-04-01

An alginate-based gel electrolyte with an ionic liquid (Alg/IL) is investigated for electric double-layer capacitors (EDLCs) by using physicochemical and electrochemical measurements. The Alg/EMImBF4 (EMImBF4 = 1-ethyl-3-methylimidazolium tetrafluoroborate) gel electrolyte is thermally stable up to 280 °C, where EMImBF4 decomposes. Furthermore, the EDLC with the gel electrolyte can be operated even at high temperature. The cell containing Alg/EMImBF4 is also electrochemically stable even under high voltage (∼3.5 V) operation. Thus, the alginate is a suitable host polymer for the gel electrolyte for EDLCs. According to the result of charge-discharge characteristics, the voltage drop in the charge-discharge curve for the cell with Alg/EMImBF4 gel electrolyte is considerably smaller than that with liquid-phase EMImBF4 electrolyte. To clarify the effect of Alg in contact with the activated carbon electrode, we also prepared an Alg-containing ACFC electrode (Alg + ACFC), and evaluated its EDLC characteristics in liquid EMImBF4. The results prove that the presence of Alg close to the active materials significantly reduces the internal resistance of the EDLC cell, which may be attributed to the high affinity of Alg to activated carbon.

Influence of low temperature ageing on optical and mechanical properties of transparent yittria stabilized-zirconia cranial prosthesis

NASA Astrophysics Data System (ADS)

Davoodzadeh, Nami; Uahengo, Gottlieb; Halaney, David; Garay, Javier E.; Aguilar, Guillermo

2018-02-01

Laser-based diagnostics and therapeutics show promise for many neurological disorders. However, the poor transparency of cranial bone limits the spatial resolution and interaction depth that can be achieved. We addressed this limitation previously, by introducing a novel cranial prosthesis made of a transparent nanocrystalline yttria-stabilized zirconia (nc-YSZ) which aims to enhance the diagnosis and treatment of neurological diseases by providing chronic optical access to the brain. By using optical coherence tomography, we have demonstrated the initial feasibility of ncYSZ implants for cortical imaging in an acute murine model. Although zirconia-based implants have been known for their excellent mechanical properties, the in vivo application was found to be affected by long-term failures, due to low temperature degradation. Accelerated aging simulations in humid environments at slightly elevated temperatures and over long periods typically transforms the ceramic surface into a monoclinic structure through a stress-corrosion-type mechanism. It was expected that the new nc-YSZ would show sufficient resistance to humid environments in comparison to the conventional zirconia implant. However, even a modest amount of transformation can change optical characteristics such as transparency. Herein we present the results of a simulated ageing study following the guidelines from the ISO 13356:2008 on aging of surgical zirconia ceramics. Comparison of %monoclinic transformation, optical transparency and mechanical hardness of nc-YSZ samples at baseline and following 25 and 100 h hydrothermal treatments shows our implant can withstand these extended ageing treatments.

A comparison of fit of CNC-milled titanium and zirconia frameworks to implants.

PubMed

Abduo, Jaafar; Lyons, Karl; Waddell, Neil; Bennani, Vincent; Swain, Michael

2012-05-01

Computer numeric controlled (CNC) milling was proven to be predictable method to fabricate accurately fitting implant titanium frameworks. However, no data are available regarding the fit of CNC-milled implant zirconia frameworks. To compare the precision of fit of implant frameworks milled from titanium and zirconia and relate it to peri-implant strain development after framework fixation. A partially edentulous epoxy resin models received two Branemark implants in the areas of the lower left second premolar and second molar. From this model, 10 identical frameworks were fabricated by mean of CNC milling. Half of them were made from titanium and the other half from zirconia. Strain gauges were mounted close to the implants to qualitatively and quantitatively assess strain development as a result of framework fitting. In addition, the fit of the framework implant interface was measured using an optical microscope, when only one screw was tightened (passive fit) and when all screws were tightened (vertical fit). The data was statistically analyzed using the Mann-Whitney test. All frameworks produced measurable amounts of peri-implant strain. The zirconia frameworks produced significantly less strain than titanium. Combining the qualitative and quantitative information indicates that the implants were under vertical displacement rather than horizontal. The vertical fit was similar for zirconia (3.7 µm) and titanium (3.6 µm) frameworks; however, the zirconia frameworks exhibited a significantly finer passive fit (5.5 µm) than titanium frameworks (13.6 µm). CNC milling produced zirconia and titanium frameworks with high accuracy. The difference between the two materials in terms of fit is expected to be of minimal clinical significance. The strain developed around the implants was more related to the framework fit rather than framework material. © 2011 Wiley Periodicals, Inc.

The effect of subpressure on the bond strength of resin to zirconia ceramic.

PubMed

Li, Yong-Mei; Zhuge, Rui-Shen; Zhang, Zu-Tai; Tian, Yue-Ming; Ding, Ning

2017-01-01

This study was conducted to investigate the effect of subpressure on the bond strength of resin to zirconia ceramic. The subpressure would create a pressure gradient which could clean out the bubbles in the adhesives or bonding interface. Twenty-eight pre-sintered zirconia discs were fabricated. Half of them were polished (group P, n = 14), and the rest were sandblasted (group S, n = 14). After sintered,the surface roughness of the zirconia discs was measured. Then, they were randomly divided into two subgroups (n = 7). The groups were named as follows: PC: P + no additional treatments; PP: P + 0.04 MPa after application of adhesives; SC: S + no additional treatments; and SP: S + 0.04 MPa after application of adhesives. Resin columns were bonded to the zirconia specimens to determine shear bond strength (SBS). The bonding interfaces were observed and the fracture modes were evaluated. Statistical analysis was performed on all data. The surface roughness of group S was significantly higher than that of group P (P<0.05). The SBS values were PC = 13.48 ± 0.7 MPa, PP = 15.22 ± 0.8 MPa, SC = 17.23 ± 0.7 MPa and SP = 21.68 ± 1.4 MPa. There were significant differences among the groups (P<0.05). Scanning electron microscopy (SEM) results showed that the adhesives of group SP and PP were closer and denser to the zirconia ceramic than that of group PC and SC. The proportion of the mixed fracture mode significantly increased after adding subpressure (P< 0.05). Subpressure can improve the shear bond strength of resin to zirconia ceramics and increase micro-infiltration between the adhesives and the zirconia ceramics, especially on the rough surfaces.

[Synthesis and Characterization of a Sugar Based Electrolyte for Thin-film Polymer Batteries

NASA Technical Reports Server (NTRS)

1998-01-01

The work performed during the current renewal period, March 1,1998 focused primarily on the synthesis and characterization of a sugar based electrolyte for thin-film polymer batteries. The initial phase of the project involved developing a suitable sugar to use as the monomer in the polymeric electrolyte synthesis. The monomer has been synthesized and characterized completely. Overall the yield of this material is high and it can be produced in relatively large quantity easily and in high purity. The scheme used for the preparation of the monomer is outlined along with pertinent yields.

An advanced lithium-air battery exploiting an ionic liquid-based electrolyte.

PubMed

Elia, G A; Hassoun, J; Kwak, W-J; Sun, Y-K; Scrosati, B; Mueller, F; Bresser, D; Passerini, S; Oberhumer, P; Tsiouvaras, N; Reiter, J

2014-11-12

A novel lithium-oxygen battery exploiting PYR14TFSI-LiTFSI as ionic liquid-based electrolyte medium is reported. The Li/PYR14TFSI-LiTFSI/O2 battery was fully characterized by electrochemical impedance spectroscopy, capacity-limited cycling, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The results of this extensive study demonstrate that this new Li/O2 cell is characterized by a stable electrode-electrolyte interface and a highly reversible charge-discharge cycling behavior. Most remarkably, the charge process (oxygen oxidation reaction) is characterized by a very low overvoltage, enhancing the energy efficiency to 82%, thus, addressing one of the most critical issues preventing the practical application of lithium-oxygen batteries.

Robust High-performance Dye-sensitized Solar Cells Based on Ionic Liquid-sulfolane Composite Electrolytes.

PubMed

Lau, Genevieve P S; Décoppet, Jean-David; Moehl, Thomas; Zakeeruddin, Shaik M; Grätzel, Michael; Dyson, Paul J

2015-12-16

Novel ionic liquid-sulfolane composite electrolytes based on the 1,2,3-triazolium family of ionic liquids were developed for dye-sensitized solar cells. The best performing device exhibited a short-circuit current density of 13.4 mA cm(-2), an open-circuit voltage of 713 mV and a fill factor of 0.65, corresponding to an overall power conversion efficiency (PCE) of 6.3%. In addition, these devices are highly stable, retaining more than 95% of the initial device PCE after 1000 hours of light- and heat-stress. These composite electrolytes show great promise for industrial application as they allow for a 14.5% improvement in PCE, compared to the solvent-free eutectic ionic liquid electrolyte system, without compromising device stability.

Impedance studies of a green blend polymer electrolyte based on PVA and Aloe-vera

NASA Astrophysics Data System (ADS)

Selvalakshmi, S.; Mathavan, T.; Vijaya, N.; Selvasekarapandian, Premalatha, M.; Monisha, S.

2016-05-01

The development of polymer electrolyte materials for energy generating and energy storage devices is a challenge today. A new type of blended green electrolyte based on Poly-vinyl alcohol (PVA) and Aloe-vera has been prepared by solution casting technique. The blending of polymers may lead to the increase in stability due to one polymer portraying itself as a mechanical stiffener and the other as a gelled matrix supported by the other. The prepared blend electrolytes were subjected to Ac impedance studies. It has been found out that the polymer film in which 1 gm of PVA was dissolved in 40 ml of Aloe-vera extract exhibits highest conductivity and its value is 3.08 × 10-4 S cm-1.

Electrical conductivity enhancement in heterogeneously doped scandia-stabilized zirconia

NASA Astrophysics Data System (ADS)

Varanasi, Chakrapani; Juneja, Chetan; Chen, Christina; Kumar, Binod

Composites of 6 mol% scandia-stabilized zirconia materials (6ScSZ) and nanosize Al 2O 3 powder (0-30 wt.%) were prepared and characterized for electrical conductivity by the ac impedance method at various temperatures ranging from 300 to 950 °C. All the composites characterized showed improved conductivity at higher temperatures compared to the undoped ScSZ. An average conductivity of 0.12 S cm -1 was measured at 850 °C for 6ScSZ + 30 wt.% Al 2O 3 composite samples, an increase in conductivity up to 20% compared to the undoped 6ScSZ specimen at this temperature. Microstructural evaluation using scanning electron microscopy revealed that the ScSZ grain size was relatively unchanged up to 10 wt.% of Al 2O 3 additions. However, the grain size was reduced in samples with higher (20 and 30 wt.%) additions of Al 2O 3. Small grain size, reduced quantity of the 6ScSZ material (only 70%), and improved conductivity makes these ScSZ + 30 wt.% Al 2O 3 composites very attractive as electrolyte materials in view of their collective mechanical and electrical properties and cost requirements. The observed increase in conductivity values with the additions of an insulating Al 2O 3 phase is explained in light of the space charge regions at the 6ScSZ-Al 2O 3 grain boundaries.

Balanced Fluid Versus Saline-Based Fluid in Post-operative Severe Traumatic Brain Injury Patients: Acid-Base and Electrolytes Assessment

PubMed Central

Hassan, Mohamad Hasyizan; Hassan, Wan Mohd Nazaruddin Wan; Zaini, Rhendra Hardy Mohd; Shukeri, Wan Fadzlina Wan Muhd; Abidin, Huda Zainal; Eu, Chong Soon

2017-01-01

Background Normal saline (NS) is a common fluid of choice in neurosurgery and neuro-intensive care unit (ICU), but it does not contain other electrolytes and has the potential to cause hyperchloremic metabolic acidosis with prolonged infusion. These problems may be reduced with the availability of balanced fluid (BF), which becomes a more physiological isotonic solution with the presence of complete electrolyte content. This study aimed to compare the changes in electrolytes and acid–base between NS and BF (Sterofundin® ISO) therapy for post-operative severe traumatic brain injury (TBI) patients in neuro-ICU. Methods Sixty-six severe TBI patients who required emergency craniotomy or craniectomy and were planned for post-operative ventilation were randomised into NS (n = 33) and BF therapy groups (n = 33). The calculation of maintenance fluid given was based on the Holliday-Segar method. The electrolytes and acid–base parameters were assessed at an 8 h interval for 24 h. The data were analysed using repeated measures ANOVA. Results The NS group showed a significant lower base excess (−3.20 versus −1.35, P = 0.049), lower bicarbonate level (22.03 versus 23.48 mmol/L, P = 0.031), and more hyperchloremia (115.12 versus 111.74 mmol/L, P < 0.001) and hypokalemia (3.36 versus 3.70 mmol/L, P < 0.001) than the BF group at 24 h of therapy. The BF group showed a significantly higher level of calcium (1.97 versus 1.79 mmol/L, P = 0.003) and magnesium (0.94 versus 0.80 mmol/L, P < 0.001) than the NS group at 24 h of fluid therapy. No significant differences were found in pH, pCO2, lactate, and sodium level. Conclusion BF therapy showed better effects in maintaining higher electrolyte parameters and reducing the trend toward hyperchloremic metabolic acidosis than the NS therapy during prolonged fluid therapy for postoperative TBI patients. PMID:29386975

Balanced Fluid Versus Saline-Based Fluid in Post-operative Severe Traumatic Brain Injury Patients: Acid-Base and Electrolytes Assessment.

PubMed

Hassan, Mohamad Hasyizan; Hassan, Wan Mohd Nazaruddin Wan; Zaini, Rhendra Hardy Mohd; Shukeri, Wan Fadzlina Wan Muhd; Abidin, Huda Zainal; Eu, Chong Soon

2017-10-01

Normal saline (NS) is a common fluid of choice in neurosurgery and neuro-intensive care unit (ICU), but it does not contain other electrolytes and has the potential to cause hyperchloremic metabolic acidosis with prolonged infusion. These problems may be reduced with the availability of balanced fluid (BF), which becomes a more physiological isotonic solution with the presence of complete electrolyte content. This study aimed to compare the changes in electrolytes and acid-base between NS and BF (Sterofundin® ISO) therapy for post-operative severe traumatic brain injury (TBI) patients in neuro-ICU. Sixty-six severe TBI patients who required emergency craniotomy or craniectomy and were planned for post-operative ventilation were randomised into NS ( n = 33) and BF therapy groups ( n = 33). The calculation of maintenance fluid given was based on the Holliday-Segar method. The electrolytes and acid-base parameters were assessed at an 8 h interval for 24 h. The data were analysed using repeated measures ANOVA. The NS group showed a significant lower base excess (-3.20 versus -1.35, P = 0.049), lower bicarbonate level (22.03 versus 23.48 mmol/L, P = 0.031), and more hyperchloremia (115.12 versus 111.74 mmol/L, P < 0.001) and hypokalemia (3.36 versus 3.70 mmol/L, P < 0.001) than the BF group at 24 h of therapy. The BF group showed a significantly higher level of calcium (1.97 versus 1.79 mmol/L, P = 0.003) and magnesium (0.94 versus 0.80 mmol/L, P < 0.001) than the NS group at 24 h of fluid therapy. No significant differences were found in pH, pCO 2 , lactate, and sodium level. BF therapy showed better effects in maintaining higher electrolyte parameters and reducing the trend toward hyperchloremic metabolic acidosis than the NS therapy during prolonged fluid therapy for postoperative TBI patients.

Surface modification for enhanced silanation of zirconia ceramics.

PubMed

Piascik, J R; Swift, E J; Thompson, J Y; Grego, S; Stoner, B R

2009-09-01

The overall goal of this research was to develop a practical method to chemically modify the surface of high strength dental ceramics (i.e. zirconia) to facilitate viable, robust adhesive bonding using commercially available silanes and resin cements. Investigation focused on a novel approach to surface functionalize zirconia with a Si(x)O(y) "seed" layer that would promote chemical bonding with traditional silanes. ProCAD and ZirCAD blocks were bonded to a dimensionally similar composite block using standard techniques designed for silica-containing materials (silane and resin cement). ZirCAD blocks were treated with SiCl4 by vapor deposition under two different conditions prior to bonding. Microtensile bars were prepared and subjected to tensile forces at a crosshead speed of 1 mm/min scanning electron microscopy was used to analyze fracture surfaces and determine failure mode; either composite cohesive failure (partial or complete cohesive failure within composite) or adhesive failure (partial or complete adhesive failure). Peak stress values were analyzed using single-factor ANOVA (p<0.05). Microtensile testing results revealed that zirconia with a surface treatment of 2.6 nm Si(x)O(y) thick "seed" layer was similar in strength to the porcelain group (control). Analysis of failure modes indicated the above groups displayed higher percentages of in-composite failures. Other groups tested had lower strength values and displayed adhesive failure characteristics. Mechanical data support that utilizing a gas-phase chloro-silane pretreatment to deposit ultra-thin silica-like seed layers can improve adhesion to zirconia using traditional silanation and bonding techniques. This technology could have clinical impact on how high strength dental materials are used today.

Enhanced cycling performance of a Li metal anode in a dimethylsulfoxide-based electrolyte using highly concentrated lithium salt for a lithium-oxygen battery

NASA Astrophysics Data System (ADS)

Togasaki, Norihiro; Momma, Toshiyuki; Osaka, Tetsuya

2016-03-01

Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate-based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte.

Effect of coping thickness and background type on the masking ability of a zirconia ceramic.

PubMed

Tabatabaian, Farhad; Taghizade, Fateme; Namdari, Mahshid

2018-01-01

The masking ability of zirconia ceramics as copings is unclear. The purpose of this in vitro study was to evaluate the effect of coping thickness and background type on the masking ability of a zirconia ceramic and to determine zirconia coping thickness cut offs for masking the backgrounds investigated. Thirty zirconia disks in 3 thickness groups of 0.4, 0.6, and 0.8 mm were placed on 9 backgrounds to measure CIELab color attributes using a spectrophotometer. The backgrounds included A1, A2, and A3.5 shade composite resin, A3 shade zirconia, nickel-chromium alloy, nonprecious gold-colored alloy, amalgam, black, and white. ΔE values were measured to determine color differences between the specimens on the A2 shade composite resin background and the same specimens on the other backgrounds. The color change (ΔE) values were compared with threshold values for acceptability (ΔE=5.5) and perceptibility (ΔE=2.6). Repeated measures ANOVA, the Bonferroni test, and 1-sample t tests were used to analyze data (α=.05). Mean ΔE values ranged between 1.44 and 7.88. The zirconia coping thickness, the background type, and their interaction affected the CIELab and ΔE values (P<.001). To achieve ideal masking, the minimum thickness of a zirconia coping should be 0.4 mm for A1 and A3.5 shade composite resin, A3 shade zirconia, and nonprecious gold-colored alloy, 0.6 mm for amalgam, and 0.8 mm for nickel-chromium alloy. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Electrolyte for batteries with regenerative solid electrolyte interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Jie; Lu, Dongping; Shao, Yuyan

2017-08-01

An energy storage device comprising: an anode; and a solute-containing electrolyte composition wherein the solute concentration in the electrolyte composition is sufficiently high to form a regenerative solid electrolyte interface layer on a surface of the anode only during charging of the energy storage device, wherein the regenerative layer comprises at least one solute or solvated solute from the electrolyte composition.

Improved performance and safety of lithium ion cells with the use of fluorinated carbonate-based electrolytes

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Ryan, V. S.; Surampudi, S.; Prakashi, G. K. S.; Hu, J.; Cheung, I.

2002-01-01

There has been increasing interest in developing lithium-ion electrolytes that possess enhanced safety characteristics, while still able to provide the desired stability and performance. Toward this end, our efforts have been focused on the development of lithium-ion electrolytes which contain partially and fully fluorinated carbonate solvents. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming Characteristics on carbon. Specifically, we have demonstrated the beneficial effect of electrolytes which contain the following fluorinated carbonate-based solvents: methyl 2,2,2-trifluoroethyl carbonate (MTFEC), ethyl-2,2,2 trifluoroethyl carbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl-2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (MHFPC), ethyl- 2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (EHFPC), and di-2,2,2-trifluoroethyl carbonate (DTFEC). These solvents have been incorporated into multi-component ternary and quaternary carbonate-based electrolytes and evaluated in lithium-carbon and carbon-LiNio.8Coo.202 cells (equipped with lithium reference electrodes). In addition to determining the charge/discharge behavior of these cells, a number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalatiodde-intercalation kinetics. In addition to their evaluation in experimental cells, cyclic voltammetry (CV) and conductivity measurements were performed on select electrolyte formulations to further our understanding of the trends

Materials system for intermediate temperature solid oxide fuel cells based on doped lanthanum-gallate electrolyte

NASA Astrophysics Data System (ADS)

Gong, Wenquan

2005-07-01

The objective of this work was to identify a materials system for intermediate temperature solid oxide fuel cells (IT-SOFCs). Towards this goal, alternating current complex impedance spectroscopy was employed as a tool to study electrode polarization effects in symmetrical cells employing strontium and magnesium doped lanthanum gallate (LSGM) electrolyte. Several cathode materials were investigated including strontium doped lanthanum manganite (LSM), Strontium and iron doped lanthanum cobaltate (LSCF), LSM-LSGM, and LSCF-LSGM composites. Investigated Anode materials included nickel-gadolinium or lanthanum doped cerium oxide (Ni-GDC, or Ni-LDC) composites. The ohmic and the polarization resistances of the symmetrical cells were obtained as a function of temperature, time, thickness, and the composition of the electrodes. Based on these studies, the single phase LSM electrode had the highest polarization resistance among the cathode materials. The mixed-conducting LSCF electrode had polarization resistance orders of magnitude lower than that of the LSM-LSGM composite electrodes. Although incorporating LSGM in the LSCF electrode did not reduce the cell polarization resistance significantly, it could reduce the thermal expansion coefficient mismatch between the LSCF electrodes and LSGM electrolyte. Moreover, the polarization resistance of the LSCF electrode decreased asymptotically as the electrode thickness was increased thus suggesting that the electrode thickness needed not be thicker than this asymptotic limit. On the anode side of the IT-SOFC, Ni reacted with LSGM electrolyte, and lanthanum diffusion occurred from the LSGM electrolyte to the GDC barrier layer, which was between the LSGM electrolyte and the Ni-composite anode. However, LDC served as an effective barrier layer. Ni-LDC (70 v% Ni) anode had the largest polarization resistance, while all other anode materials, i.e. Ni-LDC (50 v% Ni), Ni-GDC (70 v% NO, and Ni-GDC (50 v% Ni), had similar polarization

Optimization of Microporous Carbon Structures for Lithium-Sulfur Battery Applications in Carbonate-Based Electrolyte.

PubMed

Hu, Lei; Lu, Yue; Li, Xiaona; Liang, Jianwen; Huang, Tao; Zhu, Yongchun; Qian, Yitai

2017-03-01

Developing appropriate sulfur cathode materials in carbonate-based electrolyte is an important research subject for lithium-sulfur batteries. Although several microporous carbon materials as host for sulfur reveal the effect, methods for producing microporous carbon are neither easy nor well controllable. Moreover, due to the complexity and limitation of microporous carbon in their fabrication process, there has been rare investigation of influence on electrochemical behavior in the carbonate-based electrolyte for lithium-sulfur batteries by tuning different micropore size(0-2 nm) of carbon host. Here, we demonstrate an immediate carbonization process, self-activation strategy, which can produce microporous carbon for a sulfur host from alkali-complexes. Besides, by changing different alkali-ion in the previous complex, the obtained microporous carbon exhibits a major portion of ultramicropore (<0.7 nm, from 54.9% to 25.8%) and it is demonstrated that the micropore structure of the host material plays a vital role in confining sulfur molecule. When evaluated as cathode materials in a carbonate-based electrolyte for Li-S batteries, such microporous carbon/sulfur composite can provide high reversible capacity, cycling stability and good rate capability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of modifying the screw access channels of zirconia implant abutment on the cement flow pattern and retention of zirconia restorations.

PubMed

Wadhwani, Chandur; Chung, Kwok-Hung

2014-07-01

The effect of managing the screw access channels of zirconia implant abutments in the esthetic zone has not been extensively evaluated. The purpose of this study was to determine the effect of an insert placed within the screw access channel of an anterior zirconia implant abutment on the amount of cement retained within the restoration-abutment system and on the dislodging force. Thirty-six paired zirconia abutments and restorations were fabricated by computer-aided design and computer-aided manufacturing and were divided into 3 groups: open abutment, with the screw access channel unfilled; closed abutment, with the screw access channel sealed; and insert abutment, with a thin, tubular metal insert projection continuous with the screw head and placed into the abutment screw access channel. The restorations were cemented to the abutments with preweighed eugenol-free zinc oxide cement (TempBond NE). Excess cement was removed, and the weight of the cement that remained in the restoration-abutment system was measured. Vertical tensile dislodging forces were recorded at a crosshead speed of 5 mm/min after incubation in a 37°C water bath for 24 hours. The specimens were examined for the cement flow pattern into the screw access channel after dislodgement. Data were analyzed with ANOVA, followed by multiple comparisons by using the Tukey honestly significant difference test (α = .05). The mean (standard deviation) of retentive force values ranged from 108.1 ± 29.9 N to 148.3 ± 21.0 N. The retentive force values differed significantly between the insert abutment and both the open abutment (P < .05) and closed abutment groups (P < .01). Distinct patterns of cement failure were noted. The weight of the cement that remained in the system differed significantly, with both open abutment and insert abutment being greater than closed abutment (P < .05). Modifying the internal configuration of the screw access channel of an esthetic zirconia implant abutment with a metal

[Structure and properties of colored dental tetragonal zirconia stabilized by yttrium ceramics].

PubMed

Yi, Yuan-fu; Wang, Chen; Wen, Ning; Lin, Yong-zhao; Tian, Jie-mo

2009-10-01

To investigate the structure, mechanical and low temperature aging properties of colored dental zirconia ceramics. 5 graded colored dental zirconia ceramics were made by adding colorants and their combinations into a 3Y-TZP (tetragonal zirconia stabilized by 3mol% yttrium) powder, the green body were compacted at 200 MPa, pre-sinter at 1,050 degrees C and maintained for 2 h, then densely sintered at 1,500 degrees C for 2 h. Specimens were cut from each of the 5 graded colored blocks. Physical, mechanical properties as well as chemical stability were tested, microstructure were observed, crystalline phase were identified by X-ray diffraction (XRD), aging properties were assessed by measurement of the relative content of monoclinic phase and bending strength testing. The overall density of colored zirconia ceramics was over 99.7%, linear shrinkage was about 20%, while thermal expansion coefficient was about 11 x 10(-6) x degrees C(-1), the crystalline phase was tetragonal, bending strength was over 900 MPa which was slightly lowered than that of the uncolored zirconia, fracture toughness was slightly higher. Good chemical stability in acetic acid was observed. After aging treatment, tetragonal-to-monoclinic phase transformation was detected up to 40%, while bending strength was not significantly degraded. The results showed that colored 3Y-TZP ceramics presented good mechanical properties even after aging treatments, and was suitable for dental clinical use.

Computational and experimental characterization of a pyrrolidinium-based ionic liquid for electrolyte applications

NASA Astrophysics Data System (ADS)

Torabifard, Hedieh; Reed, Luke; Berry, Matthew T.; Hein, Jason E.; Menke, Erik; Cisneros, G. Andrés

2017-10-01

The development of Li-ion batteries for energy storage has received significant attention. The synthesis and characterization of electrolytes in these batteries are an important component of this development. Ionic liquids (ILs) have been proposed as possible electrolytes in these devices. Thus, the accurate determination of thermophysical properties for these solvents becomes important for determining their applicability as electrolytes. In this contribution, we present the synthesis and experimental/computational characterization of thermodynamic and transport properties of a pyrrolidinium based ionic liquid as a first step to investigate the possible applicability of this class of ILs for Li-ion batteries. A quantum mechanical-based force field with many-body polarizable interactions has been developed for the simulation of spirocyclic pyrrolidinium, [sPyr+], with BF4- and Li+. Molecular dynamics calculations employing intra-molecular polarization predicted larger heat of vaporization and self-diffusion coefficients and smaller densities in comparison with the model without intra-molecular polarization, indicating that the inclusion of this term can significantly effect the inter-ionic interactions. The calculated properties are in good agreement with available experimental data for similar IL pairs and isothermal titration calorimetry data for [sPyr+][BF4-].

Adhesion, proliferation and differentiation of osteoblasts on zirconia films prepared by cathodic arc deposition.

PubMed

Zhang, Shailin; Sun, Junying; Xu, Ying; Qian, Shi; Wang, Bing; Liu, Fei; Liu, Xuanyong

2013-01-01

Zirconia films were prepared on titanium by cathodic arc deposition technique. The surface topography and element composition of the films were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Osteoblast-like MG63 cells were cultured on the surface of the zirconia films in vitro, and cell behaviour was investigated, with titanium as control. The results obtained from scanning electron microscopy and immunofluorescence studies showed that the MG63 cells on ZrO2 films spread better than those on Ti. The CCK8 assay indicated that the zirconia films promoted the proliferation of MG63 cells. The results of alkaline phosphatase (ALP) activity test and the expression of osteogenic marker genes, such as ALP, collagen I and osteocalcin, demonstrated that the differentiation of MG63 cells might be enhanced by zirconia films. In addition, the zirconia films possibly regulated osteoclastogenic gene expression by stimulating the expression of osteoprotegerin and reducing the expression of receptor activator of nuclear factor-kappaB ligand. The present work suggests that the ZrO2 film is worth further consideration for orthopedic implant applications.

Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients.

PubMed

Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Ozcan, Mutlu; Lassila, Lippo

2013-12-01

This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (P<0.001). While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering <1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.

Highly conducting leakage-free electrolyte for SrCoOx-based non-volatile memory device

NASA Astrophysics Data System (ADS)

Katase, Takayoshi; Suzuki, Yuki; Ohta, Hiromichi

2017-10-01

The electrochemical switching of SrCoOx-based non-volatile memory with a thin-film-transistor structure was examined by using liquid-leakage-free electrolytes with different conductivities (σ) as the gate insulator. We first examined leakage-free water, which is incorporated in the amorphous (a-) 12CaO.7Al2O3 film with a nanoporous structure (Calcium Aluminate with Nanopore), but the electrochemical oxidation/reduction of the SrCoOx layer required the application of a high gate voltage (Vg) up to 20 V for a very long current-flowing-time (t) ˜40 min, primarily due to the low σ [2.0 × 10-8 S cm-1 at room temperature (RT)] of leakage-free water. We then controlled the σ of the leakage-free electrolyte, infiltrated in the a-NaxTaO3 film with a nanopillar array structure, from 8.0 × 10-8 S cm-1 to 2.5 × 10-6 S cm-1 at RT by changing the x = 0.01-1.0. As the result, the t, required for the metallization of the SrCoOx layer under small Vg = -3 V, becomes two orders of magnitude shorter with increase of the σ of the a-NaxTaO3 leakage-free electrolyte. These results indicate that the ion migration in the leakage-free electrolyte is the rate-determining step for the electrochemical switching, compared to the other electrochemical process, and the high σ of the leakage-free electrolyte is the key factor for the development of the non-volatile SrCoOx-based electro-magnetic phase switching device.

Preparation and electrochemical characterization of gel polymer electrolyte based on electrospun polyacrylonitrile nonwoven membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Raghavan, Prasanth; Manuel, James; Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Jou-Hyeon; Nah, Changwoon

Electrospun membranes of polyacrylonitrile are prepared, and the electrospinning parameters are optimized to get fibrous membranes with uniform bead-free morphology. The polymer solution of 16 wt.% in N, N-dimethylformamide at an applied voltage of 20 kV results in the nanofibrous membrane with average fiber diameter of 350 nm and narrow fiber diameter distribution. Gel polymer electrolytes are prepared by activating the nonwoven membranes with different liquid electrolytes. The nanometer level fiber diameter and fully interconnected pore structure of the host polymer membranes facilitate easy penetration of the liquid electrolyte. The gel polymer electrolytes show high electrolyte uptake (>390%) and high ionic conductivity (>2 × 10 -3 S cm -1). The cell fabricated with the gel polymer electrolytes shows good interfacial stability and oxidation stability >4.7 V. Prototype coin cells with gel polymer electrolytes based on a membrane activated with 1 M LiPF 6 in ethylene carbonate/dimethyl carbonate or propylene carbonate are evaluated for discharge capacity and cycle property in Li/LiFePO 4 cells at room temperature. The cells show remarkably good cycle performance with high initial discharge properties and low capacity fade under continuous cycling.

Effects of Polishing Bur Application Force and Reuse on Sintered Zirconia Surface Topography.

PubMed

Fischer, N G; Tsujimoto, A; Baruth, A G

2018-03-16

Limited information is available on how to polish and finish zirconia surfaces following computer-aided design/computer-aided manufacturing (CAD/CAM), specifically, how differing application forces and reuse of zirconia polishing systems affect zirconia topography. To determine the effect of differing, clinically relevant, polishing application forces and multiple usages of polishing burs on the surface topography of CAD/CAM zirconia. One hundred twenty 220-grit carbide finished zirconia disks were sintered according to manufacturer's directions and divided into two groups for the study of two coarse polishing bur types. Each group was divided into subgroups for polishing (15,000 rpm) at 15 seconds for 1.0 N, 4.5 N, or 11 N of force using a purpose-built fixture. Subgroups were further divided to study the effects of polishing for the first, fifth, 15th, and 30th bur use, simulating clinical procedures. Unpolished surfaces served as a control group. Surfaces were imaged with noncontact optical profilometry (OP) and atomic force microscopy (AFM) to measure average roughness values (Ra). Polishing burs were optically examined for wear. Scanning electron microscopy (SEM) was performed on burs and zirconia surfaces. One-way ANOVA with post hoc Tukey HSD (honest significant difference) tests (α=0.05) were used for statistical analyses. AFM and OP Ra values of all polished surfaces were significantly lower than those of the unpolished control. Different polishing forces and bur reuse showed no significant differences in AFM Ra. However, significant differences in OP Ra were found due to differing application forces and bur reuse between the first and subsequent uses. SEM and optical micrographs revealed notable bur wear, increasing with increasing reuse. SEM and AFM micrographs clearly showed polished, periodic zirconia surfaces. Nanoscale topography, as analyzed with kurtosis and average groove depth, was found dependent on the specific polishing bur type. These in

Polymer Ni-MH battery based on PEO-PVA-KOH polymer electrolyte

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen

An alkaline polymer electrolyte film has been prepared by a solvent-casting method. Poly(vinyl alcohol), PVA is added to improve the ionic conductivity of the electrolyte. The ionic conductivity increases from 10 -7 to 10 -2 S cm -1 at room temperature when the weight percent ratio of poly(ethylene oxide), PEO to PVA is increased from 10:0 to 5:5. The activation energy of the ionic conductivity for the PEO-PVA-KOH polymer electrolyte is 3-8 kJ mol -1. The properties of the electrolyte film are characterized by a wide variety of techniques and it is found that the film exhibits good mechanical stability and high ionic conductivity at room temperature. The application of such electrolyte films to nickel-metal-hydride (Ni-MH) batteries is examined and the electrochemical characteristics of a polymer Ni-MH battery are obtained.

Lithium-Ion Electrolytes Containing Phosphorous-Based, Flame-Retardant Additives

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Smith, Kiah A.; Bugga, Ratnakumar V.; Prakash, G. K. Surya

2010-01-01

Future NASA missions aimed at exploring Mars, the Moon, and the outer planets require rechargeable batteries that can operate over a wide temperature range (-60 to +60 C) to satisfy the requirements of various applications. In addition, many of these applications will require improved safety, due to their use by humans. Currently, the state-of-the-art lithium-ion (Li-ion) system has been demonstrated to operate over a wide range of temperatures (-40 to +40 C); however, abuse conditions can often lead to cell rupture and fire. The nature of the electrolyte can greatly affect the propensity of the cell/battery to catch fire, given the flammability of the organic solvents used within. Li-ion electrolytes have been developed that contain a flame-retardant additive in conjunction with fluorinated co-solvents to provide a safe system with a wide operating temperature range. Previous work incorporated fluorinated esters into multi-component electrolyte formulations, which were demonstrated to cover a temperature range from 60 to +60 C. This work was described in Fluoroester Co-Solvents for Low-Temperature Li+ Cells (NPO-44626), NASA Tech Briefs, Vol. 33, No. 9 (September 2009), p. 37; and Optimized Li-Ion Electrolytes Con tain ing Fluorinated Ester Co-Solvents (NPO-45824), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 48. Other previous work improved the safety characteristics of the electrolytes by adding flame-retardant additives such as triphenyl phosphate (TPhPh), tri-butyl phosphate (TBuPh), triethyl phosphate (TEtPh), and bis(2,2,2-trifluoroethyl) methyl phosphonate (TFMPo). The current work involves further investigation of other types of flame-retardant additives, including tris(2,2,2-trifluoroethyl) phosphate, tris(2,2,2-trifluoroethyl) phosphite, triphenylphosphite, diethyl ethylphosphonate, and diethyl phenylphosphonate added to an electrolyte composition intended for wide operating temperatures. In general, many of the formulations investigated in this

Room-Temperature Performance of Poly(Ethylene Ether Carbonate)-Based Solid Polymer Electrolytes for All-Solid-State Lithium Batteries.

PubMed

Jung, Yun-Chae; Park, Myung-Soo; Kim, Duck-Hyun; Ue, Makoto; Eftekhari, Ali; Kim, Dong-Won

2017-12-13

Amorphous poly(ethylene ether carbonate) (PEEC), which is a copolymer of ethylene oxide and ethylene carbonate, was synthesized by ring-opening polymerization of ethylene carbonate. This route overcame the common issue of low conductivity of poly(ethylene oxide)(PEO)-based solid polymer electrolytes at low temperatures, and thus the solid polymer electrolyte could be successfully employed at the room temperature. Introducing the ethylene carbonate units into PEEC improved the ionic conductivity, electrochemical stability and lithium transference number compared with PEO. A cross-linked solid polymer electrolyte was synthesized by photo cross-linking reaction using PEEC and tetraethyleneglycol diacrylate as a cross-linking agent, in the form of a flexible thin film. The solid-state Li/LiNi 0.6 Co 0.2 Mn 0.2 O 2 cell assembled with solid polymer electrolyte based on cross-linked PEEC delivered a high initial discharge capacity of 141.4 mAh g -1 and exhibited good capacity retention at room temperature. These results demonstrate the feasibility of using this solid polymer electrolyte in all-solid-state lithium batteries that can operate at ambient temperatures.

A Comparison of Electrolytic Capacitors and Supercapacitors for Piezo-Based Energy Harvesting

DTIC Science & Technology

2013-07-01

A Comparison of Electrolytic Capacitors and Supercapacitors for Piezo-Based Energy Harvesting by Matthew H. Ervin, Carlos M. Pereira, John R...Capacitors and Supercapacitors for Piezo-Based Energy Harvesting Matthew H. Ervin Sensors and Electronic Devices Directorate, ARL Carlos M. Pereira... Supercapacitors for Piezo-Based Energy Harvesting 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Matthew H

In Situ Formation of Polysulfonamide Supported Poly(ethylene glycol) Divinyl Ether Based Polymer Electrolyte toward Monolithic Sodium Ion Batteries.

PubMed

Zhang, Jianjun; Wen, Huijie; Yue, Liping; Chai, Jingchao; Ma, Jun; Hu, Pu; Ding, Guoliang; Wang, Qingfu; Liu, Zhihong; Cui, Guanglei; Chen, Liquan

2017-01-01

Sodium ion battery is one of the promising rechargeable batteries due to the low-cost and abundant sodium sources. In this work, a monolithic sodium ion battery based on a Na 3 V 2 (PO 4 ) 3 cathode, MoS 2 layered anode, and polyether-based polymer electrolyte is reported. In addition, a new kind of polysulfonamide-supported poly(ethylene glycol) divinyl ether based polymer electrolyte is also demonstrated for monolithic sodium ion battery via in situ preparation. The resultant polymer electrolyte exhibits relatively high ionic conductivity (1.2 mS cm -1 ) at ambient temperature, wide electrochemical window (4.7 V), and favorable mechanical strength (25 MPa). Moreover, such a monolithic Na 3 V 2 (PO 4 ) 3 /MoS 2 sodium ion battery using this polymer electrolyte delivers outstanding rate capability (up to 10 C) and superior cyclic stability (84%) after 1000 cycles at 0.5 C. What is more essential, such a polymer electrolyte based soft-package monolithic sodium ion cell can still power a red light emitting diode lamp and run finite times without suffering from any internal short-circuit failures, even in the case of a bended and wrinkled state. Considering these aspects, this work no doubt provides a new approach for the design of a high-performance polymer electrolyte toward monolithic sodium ion battery with exceptional rate capability and high safety. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel electrochemical sensor based on zirconia/ordered macroporous polyaniline for ultrasensitive detection of pesticides.

PubMed

Wang, Yonglan; Jin, Jun; Yuan, Caixia; Zhang, Fan; Ma, Linlin; Qin, Dongdong; Shan, Duoliang; Lu, Xiaoquan

2015-01-21

A simple and mild strategy was proposed to develop a novel electrochemical sensor based on zirconia/ordered macroporous polyaniline (ZrO2/OMP) and further used for the detection of methyl parathion (MP), one of the organophosphate pesticides (OPPs). Due to the strong affinity of phosphate groups with ZrO2 and the advantages of OMP such as high catalytic activity and good conductivity, the developed sensor showed a limit of detection as low as 2.28 × 10(-10) mol L(-1) (S/N = 3) by square-wave voltammograms, and good selectivity, acceptable reproducibility and stability. Most importantly, this novel sensor was successfully applied to detect MP in real samples of apple and cabbage. It is expected that this method has potential applications in electrochemical sensing platforms with simple, sensitive, selective and fast analysis.

Thin film polymeric gel electrolytes

DOEpatents

Derzon, Dora K.; Arnold, Jr., Charles; Delnick, Frank M.

1996-01-01

Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

Present status of solid state photoelectrochemical solar cells and dye sensitized solar cells using PEO-based polymer electrolytes

NASA Astrophysics Data System (ADS)

Singh, Pramod Kumar; Nagarale, R. K.; Pandey, S. P.; Rhee, H. W.; Bhattacharya, Bhaskar

2011-06-01

Due to energy crises in the future, much effort is being directed towards alternate sources. Solar energy is accepted as a novel substitute for conventional sources of energy. Out of the long list of various types of solar cells available on the market, solid state photoelectrochemical solar cells (SSPECs) and dye sensitized solar cells (DSSCs) are proposed as an alternative to costly crystalline solar cell. This review provides a common platform for SSPECs and DSSCs using polymer electrolyte, particularly on polyethylene oxide (PEO)-based polymer electrolytes. Due to numerous advantageous properties of PEO, it is frequently used as an electrolyte in both SSPECs as well as DSSCs. In DSSCs, so far high efficiency (more than 11%) has been obtained only by using volatile liquid electrolyte, which suffers many disadvantages, such as corrosion, leakage and evaporation. The PEO-based solid polymer proves its importance and could be used to solve the problems stated above. The recent developments in SSPECs and DSSCs using modified PEO electrolytes by adding nano size inorganic fillers, blending with low molecular weight polymers and ionic liquid (IL) are discussed in detail. The role of ionic liquid in modifying the electrical, structural and photoelectrochemical properties of PEO polymer electrolytes is also described.