Application Of Zirconia Research Articles

Novel protein stabilization in white wine: A study on thermally treated zirconia-alumina composites

A major concern for wineries is haze formation in white wines due to protein instability. Despite its prevalent use, the conventional bentonite method has shortcomings, including potential alteration of color and aroma, slow processing times, and notable wine wastage. Zirconium oxide (ZrO2) effectively removes proteins without affecting wine characteristics. However, producing cost-effective ZrO2 materials with efficient protein removal capabilities poses a significant challenge. This research aims to assess the viability of designing a porous material impregnated with zirconia to remove turbidity-causing proteins effectively. For this purpose, the support material alone (Al2O3) and the zirconia-impregnated support (ZrO2/Al2O3) were subjected to different calcination temperatures. It was observed that high-temperature treatments (750 °C) enhanced wine stability and protein adsorption capacity. The optimal adsorbent achieved a notable reduction in turbidity, decreasing the ΔNTU from 42 to 18, alongside a significant 44 % reduction in the total protein content, particularly affecting proteins in the molecular weight range of 10 to 70 kDa. This result is attributed to modifying the textural properties of ZrO2/Al2O3, characterized by the reduction of acidic sites, augmented pore diameters from 4.81 to 7.74 nm, and the emergence of zirconia clusters across the surface of the porous support. In summary, this study presents the first application of zirconia on the alumina support surface for protein stabilization in white wine. Combining ZrO2/Al2O3 and a high-temperature treatment emerges as a promising, cost-efficient, and environmentally sustainable strategy for protein removal in white wine.

Femtosecond Pulsed Laser Irradiation of Zirconia for Embedding Silver Nanoparticles in Surface Nanopores

Femtosecond pulsed laser irradiation was performed to investigate the feasibility and fundamental characteristics of embedding silver nanoparticles onto zirconia ceramic surfaces. By irradiating laser, nanopores were fabricated on the surface of the yttria-stabilized zirconia (YSZ) substrate, and silver nanoparticles were infiltrated and immobilized into the pores using a commercial nano-silver dispersion solution. Numerous nanopores embedded with silver nanoparticles were successfully obtained on the YSZ surface while keeping the grains’ shapes unchanged by controlling laser parameters. Optimizing laser fluence and scanning speed near the ablation threshold made it possible to remove only the excess dispersant that remained on the surface while keeping silver in the pores and without causing machining of the surface of the YSZ substrate. In addition, about 60% embedding in the nanopores was achieved. It was found that the shorter pulse width was suitable to avoid evaporating both dispersant and silver. Cross-sectional observation revealed that the silver nanoparticles were agglomerated to form clumps and were embedded without a gap at the bottom of the pores at a depth of about 600 nm. After laser irradiation, no significant laser-induced phase change was observed in the YSZ substrate, indicating that there was no in-process thermal damage to the bulk. These findings demonstrated the possibility of adding a metal nanoparticle to the zirconia surface by using only a laser process without damaging the properties of the base material during the process. New applications of zirconia, such as the generation of functional surfaces with antibacterial properties, are expected.

Comparison of zirconia degradation in dental implants and femoral balls: an X-ray diffraction and nanoindentation study

BackgroundNew tetragonal zirconia polycrystal dental implants stabilized with yttria (Y-TZP) have appeared in the implantology market in the form of single piece or two-piece zircona implant system. These new type of implants improve the aesthetical properties compared to conventional commercially pure (c.p.) titanium used for implants, although the long term mechanical behavior of these new implants is not yet well known. In orthopaedics, the application of zirconia as femoral balls presented an important controversial use due to the premature fracture once implanted. Y-TZP dental implants can be affected by hydrothermal degradation and its behavior should be analysed to avoid a premature fracture. The scientific question behind the study is to analyse if the degradation mechanism observed in orthopaedics applications of Y-TZP is similar to that of Y-TZP for dental applications.Materials and methodsFor this purpose, 30 original Y-TZP dental implants and 42 Y-TZP femoral balls fractured in vivo have been studied. Dental implants were submitted to an accelerated hydrothermal degradation to compare with the femoral balls fractured in vivo. Phase transformation as well as the mechanical behaviour of the degraded samples was studied by X ray diffraction and nanoindentation tests, respectively.ResultsResults have shown that the fracture mechanism of dental implants does not resemble the mechanism observed in orthopaedic samples, presenting a good long-term behaviour.ConclusionThe results ensure the good performance of zirconia dental implants, because the degradation of the ceramic is very limited and does not affect the mechanical properties.

The Survival Of All Ceramic Crowns With A Zirconia Core (Lava™)

Background: Few studies have assessed the survival of restorations and particularly zirconia based crowns in the restoration of the severely worn dentition. This study aimed to determine survival and factors associated with failure in anterior teeth worn through to dentine restored with Lava™ crowns. Methods: A convenience sample of 30 participants (27 male, 3 female) had 161 Lava™ crowns placed by one specialist clinician in a hospital setting. Follow-up was over a median 72 month period. Results: Of the 161 Lava™ crowns only 25 failed (15.5%) in 15 individuals up to 84 months for the longest case. Major failures were total debond (N=7) or minor delamination chips within the veneer ceramic layer (N=18). The mean time to first failure was 25.23 months. The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months (95%CI 70.4, 77.3). Failures by subject were not associated with an increase in Occlusal Vertical Dimension using a Dahl approach but were associated with an edge-to-edge incisal relation (p<0.05), attrition (p<0.05) and bruxism (p<0.005). Conclusion: The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months. The high loads in bruxism result in increased risk of fracture or debond. Clinical relevance: A protective bi-laminar splint is thus advisable. Nonetheless, application of zirconia based crowns in a difficult clinical situation such as bruxism can be a successful treatment modality.

Fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal clasps for removable partial dentures.

With the rapid development of computer-aided design/computer-aided manufacturing (CAD/CAM) systems, the application of zirconia in removable partial dentures is expected to expand. Clasps composed of zirconia should improve esthetics without inducing the risk of metal allergy. The aim of this study was to examine the fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) clasps for removable partial dentures. Yttria-stabilized tetragonal zirconia polycrystal and cobalt-chromium (Co-Cr) alloy were prepared using CAD/CAM systems. Specimens were either of the semicircular type or of the flat type, with cross-sectional areas of taper ratios of 0.50, 0.75, and 1.00. All specimens were tested using the cantilever test and the constant displacement fatigue test, and data were analyzed using ANOVA. During the cantilever test, the maximum displacement prior to fracture was greater than the required undercut, and the semicircular-type specimen exhibited a higher fracture load than the flat type. None of the specimens displayed permanent deformation and showed almost the same degree of deformation after fatigue testing. A lower taper ratio was associated with lower average load values and greater displacement. Within the limitations of this study, it was possible to conclude that Y-TZP provides the required undercut and adequate retentive force for removable partial denture clasps. Additionally, Y-TZP and Co-Cr alloy had almost the same degree of deformation even after the simulated lifespan of removable partial dentures.

SURFACE CHARACTERIZATION OF ZrO2/Zr COATING ON Ti6Al4V AND IN VITRO EVALUATION OF CORROSION BEHAVIOR AND BIOCOMPATIBILITY

Biocompatibility is crucial for implants. In recent years, numerous researches were conducted aiming to modify titanium alloys, which are the most extensively used materials in orthopedic fields. The application of zirconia in the biomedical field has recently been explored. In this study, the biological ZrO2 coating was synthesized on titaniumalloy (Ti6Al4V) substrates by a duplex-treatment technique combining magnetron sputtering with micro-arc oxidation (MAO) in order to further improve the corrosion resistance and biocompatibility of Ti6Al4V alloys. The microstructures and phase constituents of the coatings were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the surface wettability was evaluated by contact angle measurements. The results show that ZrO2 coatings are porous with pore sizes less than 2[Formula: see text][Formula: see text]m and consist predominantly of the tetragonal ZrO2 (t-ZrO[Formula: see text] and cubic ZrO2(c-ZrO[Formula: see text] phase. Electrochemical tests indicate that the corrosion rate of Ti6Al4V substrates is appreciably reduced after surface treatment in the phosphate buffer saline (PBS). In addition, significantly improved cell adhesion and growth were observed from the ZrO2/Zr surface. Therefore, the hybrid approach of magnetron sputtering and MAO provides a surface modification for Ti6Al4V to achieve acceptable corrosion resistance and biocompatibility.

Zirconia Surface Treatment by Different Output Powers of Er: YAG Laser and Sandblasting: SEM Evaluation

Background: Application of zirconia in dentistry has increased due to its good properties. Since zirconia is not possible to be etched, evaluation of the other methods of surface treatment is important. Objectives: The aim of this study was to evaluate zirconia surfaces treated by different output powers of Er: YAG laser and sandblasting technique by scanning electron microscope (SEM). Materials and Methods: 15 specimens were prepared of 3Y-TZP ceramic material. After polishing of all the samples, divided into 5 groups; control group, 1.5 W Er: YAG laser irradiated group, 2.5W Er: YAG laser irradiated group, 3.5 W Er: YAG laser irradiated and sandblasted group. Then SEM image of each group were prepared and analyzed. Results: The SEM images of study groups showed there is no significant difference between control group and laser groups at × 3000, but at the more magnifications (× 15000 and × 60000), with increasing laser power, surface roughness and deformation of crystals increases. SEM of Sandblasted group showed a change in surface texture with the formation of microretentive grooves and deformation of zirconia crystals shape. Conclusions: By increasing the Er: YAG laser power on zirconia ceramics, the surface roughness increases but not impressive. Application of sandblasting technique on zirconia provides greater surface roughness than Er: YAG laser treatment. 1.5 W (150 mJ) Er: YAG laser radiation has no significant effect on surface morphology of zirconia but 2.5 W (250 mJ) and 3.5 W (350 mJ) outputs, change the surface morphology.

Electrocatalytic Enhancement Effects at Platinized Nanoporous Substrates: Oxidation of Ethanol at PtRu Nanoparticles Dispersed over Rh-Containing ZrO2 Support

Nanostructured platinum is so far the best-known and the most active catalyst for the activation of small organic molecules via their specific adsorption and interfacial dissociation However, the ability of platinum to break effectively the C–C bonds is largely limited by side poisoning effects originating from the strong adsorption of COads on Pt surfaces at low (below 60 or even 80 oC). Several two-carbon containing molecules have been reported as undesirable intermediates during ethanol oxidation at polycrystalline Pt, most of them requiring relatively high potentials for complete oxidation.It is commonly accepted that the highest efficiency for electrooxidation of ethanol was achieved at carbon-supported PtSn (PtSn/C) catalysts and, more recently, very promising result were obtained with PtRh type systems. Despite the relatively good performance of the PtSn/C based anodes, the overall efficiency is still poor when compared to oxidation of hydrogen (at Pt) or even methanol (at PtRu). The main products remain acetaldehyde (2-electron oxidation) and acetic acid (4-electron oxidation) thus further modification of existing catalysts is necessary to obtain higher efficiency. There is a need to remove not only the poisoning CO adsorbates but also to activate the ethanol molecule and to break C-C bonds effectively. More recently, modification of the platinum-based surface is achieved by adding the second additive namely by introducing the second alloying metal.We propose a hybrid electrocatalytic material for oxidation of ethanol utilized PtRu nanoparticles dispersed over thin-films of rhodium-containing zirconia. The system is particularly active when it has been deposited onto such platinized nanoporous substrate as silica-nanosphere-layered solid-assembly. Morphologies of the resulting catalytic surfaces were characterized here using electrochemical techniques as well as transmission and scanning electron microscopies. The enhancement of activity of PtRu nanoparticles (in 0.5 mol dm-3 H2SO4 at room temperature in the presence of ethanol) has been evident from the comparative electrochemical (voltammetric, chronoamperometric) experiments performed with use of Rh-containing and Rh-free ZrO2 films deposited onto platinized nanoporous plates. It is apparent from additional diagnostic chronoamperometric experiments (executed at inert glassy carbon electrode substrates) that electrocatalytic currents measured at potentials as low as 0.3 V (vs. RHE) are significantly larger upon application of zirconia and, particularly, Rh-containing zirconia supports for dispersed PtRu nanoparticles. The results are also consistent with the strong enhancement effect originating from the use of platinized silica-nanosphere-layered solid-assemblies. The overall activation effect may have origin in the existence of large population of hydroxyl groups (from zirconia) in the vicinity of platinum (from PtRu alloy nanoparticles) capable of inducing oxidative removal of passivating CO adsorbates. The presence of rhodium within zirconia seems to not only enhance conductivity but also to interact specifically with the oxide and/or dispersed catalytic centers. By analogy to titania, zirconia may influence activity of ruthenium oxo species in the oxidative removal of passivating (e.g. CO) intermediates. High surface area platinized nanoporous substrates enlarge the overall catalytic active area and, most likely, provide reactive sites for C-C bond breaking in the ethanol molecule.

Insights into Porcelain to Zirconia Bonding

The application of zirconia, ZrO2, as a biomaterial in medicine started in the early 1980s. Since then, numerous studies have been conducted on this special ceramic material to assess and discover its unique characteristics in practical biomedical applications. Also, zirconia has manifested its extraordinary advantages for use in dental clinical practice since the late 1990s, such as its excellent biocompatibility, good aesthetical appeal and outstanding biomechanical properties. With the development of fabrication methods and more extensive comprehension of this material, zirconia has been employed in more and more dental restorations from single crowns and root canal posts to long-span fixed dentures and, very recently, even as dental implants. However, there are still some drawbacks in its dental applications. Such drawbacks are its relatively weak bonding with porcelain when compared with metal-ceramic system, less reliable bonding with resin-based adhesives, and possible failures caused, e.g., by the effects of low temperature degradation. Although many studies have been carried out on porcelain to zirconia bonding, a thorough understanding of its real mechanism is still far from being achieved. The effects of different treatments before or during the veneering procedure are not clearly elucidated, thus they need further investigations. The aim of this article is to outline the characteristics of zirconia and descriptions of porcelain to zirconia interfacial bonding based on the research conducted in the past few years.

Zirconia-Based Stationary Phases for Chiral Separation: Mini Review

Separation of enantiomers is one of the most interesting and challenging tasks in the field of separation science. High-performance liquid chromatography (HPLC) and recently capillary electrochromatography (CEC) using chiral stationary phases (CSP) are two of the most useful techniques for both enantioseparation and determination of enantiomeric composition. Although silica has been extensively used as the base material for the stationary phases due to attractive properties including desirable mechanical strength, surface characteristics, catalytic inertness, and surface derivatization possibilities, it has some inherent shortcomings including the narrow range of pH and thermal stability. The zirconia-based stationary phases have shown excellent performance in the separation of wide range of compounds and have been considered as an alternative to silica-based stationary phases due to desirable chemical and physical properties such as resistance to thermal conditions, resistance to extreme pHs, and mechanical stability. Recently, zirconia-based CSPs in either particle-packed or monolithic columns have received considerable attention. This mini-review reports the development and applications of zirconia based stationary phases for chiral separations by HPLC and CEC.

Zirconia in Fixed Implant Prosthodontics

CAD/CAM technology in combination with zirconia ceramic has increasingly gained popularity in implant dentistry. This narrative review presents the current knowledge on zirconia utilized as framework material for implant-borne restorations and implant abutments, laboratory tests and developments, clinical performance, and possible future trends for implant dentistry are addressed. A review of available literature from 1990 through 2010 was conducted with search terms zirconia,""implants,""abutment,""crown," and "fixed dental prosthesis" using electronic databases (PubMed) and manual searching. Latest applications of zirconia in implant dentistry include implant abutments, multiple unit and full-arch frameworks as well as custom-made bars to support fixed and removable prostheses. High biocompatibility, low bacterial surface adhesion as well as favorable chemical properties of zirconia ceramics are reported. Zirconia stabilized with yttrium oxide exhibits high flexural strength and fracture toughness due to a transformation toughening mechanism. Preliminary clinical data confirmed the high stability of zirconia for abutments and as a framework material for implant borne crowns and fixed dental prostheses. Zirconia abutment or framework damage has rarely been encountered. However, veneering porcelain fractures are the most common technical complication in implant-supported zirconia restorations. These porcelain veneer failures have led to concerns regarding differences in coefficient of thermal expansions between core and veneering porcelain and their respective processing techniques. As presently evidence of clinical long-term data is missing, caution with regard to especially extensive implant-borne zirconia frameworks is recommended.

Manufacturing of new nano-structured ceramic–metallic composite microporous membranes consisting of ZrO 2, Al 2O 3, TiO 2 and stainless steel

Frequently, the membrane employed in a traditional nano-filtration (NF) or gas separation (GS) membrane device consists of a polymeric material, having significant disadvantages including a restricted mechanical, chemical and thermal stability. As an alternative for the polymeric membranes, ceramic membranes with an improved stability have been introduced, but the current membranes still suffer from stability problems (e.g. brittle material, restricted chemical stability in water vapour). This paper reports the preparation of novel hybrid metallic–ceramic membranes, based on a porous 316L stainless-steel support material. The optimized membranes were made by deposition of a fine suspension with a particle size of ~ 180 nm, a colloidal sol with a particle size of ~ 30 nm and a nano-particle sol with a particle size of ~ 5 nm and show a comparable multilayer structure as current ceramic membranes for micro-, ultra- and nano-filtration and gas separation. The essential new features of the membranes include the use of an alternative metallic support material, which provides a high mechanical stability to the membrane, and the application of zirconia- and titania based functional membrane layers, which display a high chemical and thermal stability for potential filtration or gas separation applications.

The Pore Structure of Zirconia for Liquid Chromatography

Interest in zirconia as a chromatography support has increased considerably recently because of its chemical inertness and its promise as a useful support, particularly in biological systems. While studies have mainly focused on applications using zirconia or the control of complex elution behaviour that is often observed on this surface, many of the papers presented have not considered the importance of using materials with optimised pore structures. As a result, the efficiency of some separations may have been compromised. In this review we focus on what is perhaps the most important feature of such supports, namely, the pore structure and recent developments in this area. We have not attempted to review the many applications of zirconia in chromatography as they have been comprehensively reviewed by Nawrocki and co-workers in 19931 and again as a new material for biotechnology in 1994.2 In these reviews the usefulness of zirconia was demonstrated by the many applications that were referenced, particularly with respect to the chromatography of biological species.

Development of ceramic waste forms for actinide-rich waste— Radiation stability of perovskite and phase and chemical stabilities of ZR-and AL-based ceramics

Ceramics are considered as most promising materials for conditioning of long-lived radionuclides because of their outstanding durability for long term. The Japan Atomic Energy Research Institute (JAERI) has developed ceramic waste forms, e.g. Synroc and zirconia-based ceramics, for the actinide-rich wastes arising from partitioning and transmutation processes. In the present study, α-decay damage effects on the density and leaching behavior of perovskite (one of three main minerals forming Synroc) were investigated by an accelerated experiment using the actinide doping technique. A decrease in density of Cm-doped perovskite reached 1.3 % at a dose of 9 × 10 17 α-decays·g −1. The leach rates (MCC-1 leach test inpH ∼ 2 solution at 90°C for 2 months) of perovskite specimens with accumulated doses of 1.6 × 10 17, 4.0 × 10 17 and 8.3 × 10 17 α-decays·g −1 were 1.7, 2.3 and 3.0 μ·m −2·day −1, respectively. Application of zirconia- and alumina-based ceramics for incorporating actinides was also investigated by the experiments using non-radioactive elements (Ce and Nd) with an emphasis on crystallographic phase stability and chemical durability. The yttria-stabilized zirconia was stable crystallographically in the wide ranges of Ce and/ or Nd content and had excellent chemical durability.

Characterization of pre-shaped zirconia bodies for catalytic applications

Literature indicates that application of zirconia in a supported dehydrogenation catalyst is viable. Textural and structural properties of commercial pre-shaped zirconia supports from various suppliers were characterized using electron microscopy, element analysis, nitrogen physisorption, mercury intrusion porosimetry and X-ray diffraction. Most zirconias are sufficiently pure (>97 %) and thermostable to be applied in supported catalysts. Specific surface areas as large as 10 m2g−1 are stable at temperatures of about 850 °C. Specific surface areas up to about 30 m2g−1 can be established by a thermal treatment in air at temperatures up to the operating temperatures of the dehydrogenation process. Steam treatment affects the texture differently from treatment in dry air: sintering proceeds more rapidly in the presence of steam. The preshaped supports show a porosity (about 50%) which is higher than that reported for zirconia powders with the same pore-size distribution (5%). This is advantageous, both in the catalyst preparation step and in the catalytic reaction. However, the pre-shaped supports exhibit some microporosity.

Technical applications of zirconia

Technical applications of zirconia