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The aim of this paper was to evaluate the fracture resistance of 3D-printed zirconia occlusal veneers (OVs) of different thicknesses and supported by different abutment materials. Materials and Methods: The standard OV of a natural molar was prepared and digitized using a laboratory 3D scanner. The resulting digital tooth abutment was milled either using cobalt–chromium (CoCr) or a fiber-reinforced composite (FRC). All the abutments were digitized and standardized OVs (30° tilt of all the cusps) designed with 0.4 mm, 0.6 mm, or 0.8 mm wall thicknesses. The OVs were fabricated using either the Programill PM7 milling device (Ivoclar Vivadent, PM) or one of two 3D zirconia printers, Cerafab 7500 (Lithoz, LC) or Zipro-D (AON, ZD). The ZD samples were only tested on CoCr abutments. The completed OVs were luted to their abutments and subjected to artificial aging, consisting of thermocycling and chewing simulation before fracture testing with a steel sphere (d = 8 mm) as an antagonist with three contact points on the occlusal OV surface. Besides the total fracture resistance Fu,tot, the lowest contact force Fu,cont leading to the local fracture of a cusp was of interest. The possible effects of the factors fabrication approach, wall thickness, and abutment material were evaluated using ANOVA (α = 0.05; SPSS Ver.28). Results: The total fracture resistance/contact forces leading to failure ranged from Fu,tot = 416 ± 83 N/Fu,cont = 140 ± 22 N for the 0.4 mm OVs fabricated using LC placed on the FRC abutments to Fu,tot = 3309 ± 394 N (ZD)/Fu,cont = 1206 ± 184 N (PM) for the 0.8 mm thick OVs on the CoCr abutments. All the factors (the fabrication approach, abutment material, and OV wall thickness) had an independent effect on Fu,tot as well as Fu,cont (p < 0.032). In pairwise comparisons for Fu,tot of the OVs luted to the CoCr abutments, the ZD samples statistically outperformed the LC- and PM-fabricated teeth irrespective of the thickness (p < 0.001). Conclusions: Within the limitations of this study, the printed occlusal veneers exhibited comparable fracture resistances to those of the milled variants. However, more resilient abutments (FRC as a simulation of dentine) as well as a thinner wall thickness led to reduced OV fracture resistance, suggesting that 0.4 mm thick zirconia OVs should not be unreservedly used in every clinical situation. [ABSTRACT FROM AUTHOR]

Fabrication of transparent or pore‐free oxide ceramics usually requires sintering in a vacuum or reducing atmosphere. In the present paper, a near‐infrared transparent Dy2Zr2O7 ceramic was prepared by ordinary pressureless sintering under the air atmosphere, with a controlled pre‐calcining of raw powders process. The key point of the process is to control the content of the phases by pre‐calcination of the starting mixture of ZrO2 and Dy2O3 powders. The influence of pre‐calcining temperature on the content of phases, the particle sizes, on the sinterability of the mixture of Dy2O3 and ZrO2 powders has been investigated. It was found that when the pre‐calcination was conducted at 1200°C for 2 h, the powder contains 4 mol% Dy2Zr2O7, 18 mol% m‐ZrO2, 30 mol% Dy2O3, and about 50 mol% t/c‐ZrO2 which is beneficial for the sintering of pore‐free Dy2Zr2O7 ceramics. The mechanism is discussed in the paper. The transparency of the sintered Dy2Zr2O7 ceramic was measured, and their transmittance is about 63% at 1450 nm and 73% at 1900 nm. This work provides a simple and convenient way to prepare the near‐infrared transparency ceramic without special sintering facilities. [ABSTRACT FROM AUTHOR]

Ceramics is a promising material that has been widely used as artificial bones. However, most available investigations were devoted to new material development and implant structure design, while few of studies focused on innovative hybrid implants that can act not only as implants but also as surgery tools for solving specific health issues. This paper innovatively designed and additively-manufactured a zirconia ceramic surgery tool, which can not only act as a drilling tool, but also retain itself in the drilled hole after the surgery as bone scaffold, at the meantime delivery active ingredient (Vitamin C) for fast recovery. To achieve early intervention, the proposed zirconia ceramic tool was additively manufactured with inter-connected pore structures that can benefit the recovery. The zirconia ceramic surgery tools (with 50 %, 70 % and 80 % porosity) showed the required mechanical properties to act as a drilling tool. The tool also showed drug releasing function with the different diffusion rates based on drug diffusion experiments. The zirconia ceramic tool with Vitamin C coating also showed enhanced cell adhesion and accelerated cell growth based on the osteoblast induction assessment. Based on above, the proposed zirconia ceramic tool is expected to bring new possibilities for wide applications of ceramic tools in surgeries. [ABSTRACT FROM AUTHOR]

Zirconia ceramics have become an important material for the manufacture of key components in aerospace, military, energy, and other fields due to their excellent mechanical properties. However, their inherent high hardness and brittleness make them difficult to machine with high efficiency and low damage, resulting in poor surface integrity. Inspired by the ribbed groove structure of shark skin and the fractal structure of insect wing veins, two zirconia ceramics with different bionic textures are designed in this paper, and zirconia ceramic surfaces are bionically textured by using an ultrafast picosecond pulse laser. The effects of the special bionic textures on the grinding behavior of zirconia ceramics, specifically surface morphology, surface roughness, edge morphology, and subsurface damage, were investigated. The experimental results show that the surface integrity of the bionic textured zirconia ceramics is better compared to the untextured surface. In particular, the bionic insect wing veins texture exhibits the best surface quality with the least sub-surface damage, and the surface roughness S a is reduced by a maximum of 21.46 %, and S z is reduced by a maximum of 18.87 %. However, the best edge morphology is exhibited by the bionic shark skin texture. Additionally, bionic texturing improves grinding lubrication and cooling conditions. The results confirm that applying bionic texturing to zirconia ceramics effectively enhances grinding performance and improves grinding surface integrity. [ABSTRACT FROM AUTHOR]

In this paper, Al2O3‐TiC ceramic composites with intragranular nano‐ZrO2 were prepared in vacuum by spark plasma sintering (SPS). The effect of ZrO2 particles with different nano‐sizes on the microstructure and mechanical properties of ceramics was studied. The results show that SPS can achieve relative densification of materials without generating new impurity phases. At the same time, the sintering densification temperature of ceramic materials can be reduced by adding ZrO2 (20 nm) particles. Under the action of SPS strong electric field, the nano‐ZrO2 adsorbed on the surface of the matrix particles can enter the interior of matrix grains, and form intragranular nanostructures when the grain boundaries move and the particles merge. The microstructure and mechanical properties of ceramic materials can be improved through the intragranular structure formed by nanoparticles. The main reasons for the increased strength and toughness of ceramic materials are crack deflection, crack bridging and transgranular fracture. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of different forming processes on the surface morphology and dimensional accuracy of zirconia ceramics, and selects the optimal forming process for mechanical property analysis. A laboratory-built ceramic laser 3D printer was used to carry out the forming experiments on the specimens. Under the condition that only the forming process of the experimental target is changed, the effects of powder layering process, scanning spacing and scanning strategy on the surface morphology and properties of zirconia ceramics are investigated. The use of two powder spreading and scanning forming processes in the sample forming process effectively improved the forming defects of zirconia ceramics caused by powder splattering, and the zirconia ceramics had a better forming effect. Under this condition, the dimensional accuracy of the specimens increases and then decreases with the decrease of the scanning spacing, where the highest dimensional accuracy is obtained when the scanning spacing is 0.158 mm; among different scanning strategies, the best surface morphology is obtained by forming specimens with the island scanning strategy. In addition, the mechanical properties of the ceramics formed from zirconia showed that the Young's modulus and Vickers hardness of the samples increased by approximately 53.6 % and 15.7 %, respectively, compared to the traditional forming process. [ABSTRACT FROM AUTHOR]

With the increasing application of ceramic structural parts, how to realize the ductile cutting of ceramics and high-quality machining of ceramic structural parts have become an important research direction. In this paper, the micromilling of fully sintered zirconia ceramics is studied using customized PCD end mills with three different rake angles. The critical thickness for microcutting of ceramics during the micromilling process is theoretically analyzed and experimentally identified. Then, the ductile cutting of ceramic materials is to be realized by controlling the key cutting parameter (feed per tooth f z) considering the critical cutting thickness. Under the condition of ductile cutting, the high-aspect-ratio vortex curved thin walls of fully sintered zirconia ceramics are successfully fabricated. Furthermore, the tool wear of the customized PCD end mill is analyzed. The tool geometric parameters that are beneficial to ensure both ductile cutting and high tool life are identified. [ABSTRACT FROM AUTHOR]

This paper deals with the synthesis of a series of zirconoaluminosiloxane (ZAS) as monophasic liquid precursors in toluene for zirconia/mullite ceramics. Precursors are synthesized by the zirconium modification of aluminosiloxane. The effect of zirconium incorporation in the aluminosilicate network is studied by FTIR, NMR, and TG/DTA analysis. 29Si and 27Al clearly indicates that zirconium is chemically bonded to the aluminosilicate network and the network connectivity increases with increase in zirconium content. 27Al NMR also reveals the progressive distortion of octahedral symmetry of AlO 6 due to zirconium incorporation, validating the insertion of Zr through Al–O–Zr bonds where Al is four coordinated. These observations attest the monophasic nature and the chemical homogeneity of the synthesized precursors, which is the main factor contributing to the low temperature crystallization of ceramic phases. Ceramic conversion studies of the precursors confirmed the formation of crystalline zirconia/mullite ceramic phases at a low temperature of 900 °C. The XRD and microstructure analysis by SEM/EDX indicated that the mullite crystallization can be controlled by zirconia incorporation. This effect is discussed in terms of the occupancy of zirconia either as intra-granular or inter-granular particles. The zirconia concentration for maximum crystallization of mullite is optimized. [Display omitted] [ABSTRACT FROM AUTHOR]

Ceramics materials based on yttria stabilised tetragonal zirconia nanopowders (3Y-TZP) are widely used in the production fuel cells, oxygen sensors, refractories, etc. and intensively studied due to their outstanding mechanical and electrical properties. To obtain ceramics with specific properties different additives can be used. This allow for control over the features of a nanopowder’ structure and its consolidation during the sintering process. It is important examine in detail the initial sintering stage of tetragonal zirconia based nanopowders modified by third element additives. The present paper shows the impact of SiO2 and SnO2 additives and the influence of different methods of dopant addition (co-precipitation and mechanical mixing) on the kinetics of the initial sintering stage of tetragonal zirconia nanopowders. It demonstrates that sintering mechanism is changed by the addition of a small amount SiO2 and SnO2 by volume to the grain boundary diffusion in 3Y-TZP nanopowders obtained by the co-precipitation method. This change led to increased activation energy. This paper explores the reasons for the acceleration in the sintering process of nanopowders 3Y-TZP with SiO2 and SnO2 additives obtained by the mixing method. It shows that the sintering mechanism is the same as that of the initial 3Y-TZP powder obtained by the co-precipitation technique. The volume diffusion mechanism was the predominant mechanism at the initial sintering stage and was accompanied by a decrease in the activation energy of the sintering process. [ABSTRACT FROM AUTHOR]

In this paper, we report the preparation of a B4C/ZrB2 composite powder material via boron carbide reduction of zirconium oxide in the presence of carbon nanofiber as a carbon reducing agent. The material was synthesized in the temperature range 1200–1900°C in 20 min. The optimal synthesis temperature was 1650°C, independent of the starting-mixture composition. We have studied characteristics of the composite powders containing 10–30 mol % ZrB2. The 50% particle size of the composite powders with the compositions studied does not exceed 9.5 μm. The powders consist of aggregated particles of the B4C and ZrB2 phases up to 10 and 40 μm in size, respectively. Visual analysis of micrographs of the powders showed that the mixtures containing 20–30 mol % ZrB2 had a uniform modifying additive distribution over the B4C particles and that the content of large and medium inclusions did not exceed 15 vol %. The specific surface area of the samples ranged from 1.3 to 2.1 m2/g. The zirconium diboride particles were uniformly distributed over the boron carbide matrix. Increasing the ZrB2 content of the composite powder material from 10 to 30 mol % improved the thermal stability of the material in an oxidizing medium. The composite material is potentially attractive for ceramic fabrication. [ABSTRACT FROM AUTHOR]

Introduction: The conditioning procedures for glass-based ceramic restorations before adhesive cementation are generally recognized. In the case of polycrystalline ceramics, which include zirconium oxide, there is still no standardized protocol. The aim of this work was to present conditioning methods of the cementation surface of zirconium oxide fixed dentures. The new generation high translucency zirconia has been also considered. Material and method: The following keywords for the PUBMED and EMBASE databases were used: zirconium oxide, zirconium oxide with increased translucency, bond strength, bending strength, surface treatment. The inclusion criteria were original papers in English published between 2015–2021. Results: Out of 1537 publications, 53 articles were selected for the study, covering methods of conditioning zirconium ceramics, including new materials with increased translucency. These procedures were divided into 5 main groups. Summary: Due to the widespread use of zirconia ceramics and the introduction of new zirconia-based materials, the use of a predictable and standardized cementation protocol is one of the most important factors contributing to the long-term clinical success of prosthetic restorations. Therefore, the research showed differences in the properties of the covered materials after conditioning. It suggests the need to create separate conditioning protocols for highly translucent and traditional zirconia. [ABSTRACT FROM AUTHOR]

Microcracks and surface/subsurface damage are easily generated in engineering ceramics grinding. Fracture toughness is an important mechanical property that affects the grinding performance of engineering ceramics, and dynamic fracture toughness accurately reflects the mechanism of crack generation and propagation mechanism in different grinding conditions. Considering the dynamic fracture toughness and grinding process parameters for zirconia ceramics with different grain sizes (50 nm/500 nm/5000 nm) in this paper, the critical grinding force and maximum subsurface damage depth models for the crack generation were established and verified by grinding experiments. The effects of dynamic fracture toughness on the material removal mechanism during the ductile–brittle transition with different process parameters were analyzed, and the influence of different grain sizes on grinding force, workpiece surface roughness, surface cracking rate, and subsurface damage depth were discussed. Experiment results showed that the dynamic fracture toughness values range from 13.0 to 15.0 Mpam1/2 with grain size 50 nm, 9.8 to 11.3 Mpam1/2 with grain size 500 nm, and 6.1 to 6.8 Mpam1/2 with grain size 5000 nm in the experimental process parameters. The relative error of the dynamic maximum subsurface damage depth is respectively 15.77%, 11.65%, and 18.36%. And the subsurface damage depth of zirconia ceramics is respectively 27 μm, 31 μm, and 40 μm with the grain size of 50 nm, 500 nm, and 5000 nm in the 5th group process parameters, which showed that the small grain size exhibited excellent grinding quality. But the influence of grain size on dynamic fracture toughness was weaker than that of grinding process parameters. [ABSTRACT FROM AUTHOR]

The need for the new materials and advanced manufacturing techniques for achieving the highest characteristics of energy devices is an obvious trend. One of the possible ways to create structures for energy applications is to introduce complex geometries and promising features with additive manufacturing (AM). Using this approach, it is possible to create complex geometry and moreover decrease the weight of materials. In this paper, we developed the layer-by-layer fabrication approach of ceramic hierarchical lattice structures via the (micro-SLA) technology. As a feedstock material, the novel composition of partly stabilized-zirconia ceramics (6ScSZ, 8YSZ) was developed. Materials were selected as a solid slurry component due to high ionic conductivity at the working temperature of modern solid oxide fuel cells (SOFCs). For the sintering, the green body heat treatment process was optimized to one step, which decrease the time and production cost. The data from scanning electron microscopy and micro-CT shows that 112-layer samples of the octet truss did not show any critical defects, and the achieved relative density was close to the theoretical one. Totally, 22 samples with the total size of 6.5 mm * 6.5 mm * 2.8 mm and the diameter of struts in the range of 240–250 μm were fabricated at a rate of only 56 min per sample, using two modifications of advanced doped zirconia-ceramics. This study opens new opportunities for the development and transfer to the production of additive manufacturing of ceramics to build energy systems devices such as solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Zirconia, a bio-ceramic, is widely utilized in bioengineering, biomedical implants, dentistry, and the automotive industry due to high hardness, excellent wear resistance, etc. However, it is difficult to attain micro features on zirconia utilizing a laser machining system for the aforesaid properties. The paper deals with the study of the Heat Affected Zone (HAZ) formation during the micro-channel milling (V-shaped cross-sections) of zirconia utilizing a nanosecond fiber laser system. Experiments are accomplished to examine the consequence of control variables namely transverse feed, pulse frequency, laser power, scan number, and scan speed. The influence of each of the laser process variables on response parameter are studied in order to get the significant trends of laser parameters. With the increment of laser power, the number of pass and transverse feed, HAZ width dimensions tend to increase. The reverse phenomena are observed for pulse frequency and scan speed. The lower HAZ width which is achieved as 31.74 µm at a parametric setting of average power at 10 W, pulse frequency at 65 kHz, scanning speed at 11 mm/s, a number of pass at 1, transverse feed at 0.005 mm. [ABSTRACT FROM AUTHOR]

In zirconia‐based shape memory ceramics (SMCs), cracking during the martensitic transformation can be avoided in structures that reduce the relative presence of grain boundaries where high levels of transformation mismatch stress develop. This approach has been well established in single crystals, but only for sample sizes below about 5 microns. In this paper, we extend the strategy of eliminating grain boundaries to bulk specimen scales by fabricating mm‐scale single crystal SMCs via cold crucible induction melting. For 1.5 and 2.0 mol% Y2O3‐ZrO2, we study the cyclic martensitic transformation of both single crystal and polycrystal structures. Whereas single crystals have very repeatable transformation behavior in terms of hysteresis and strain amplitude, polycrystals degrade dramatically as they accumulate cracking damage with repeated cycling. As the polycrystal evolves from a pellet to granular packing of loose single crystals/grains, the energy dissipation converges with that of the single‐crystal structure, and the energy spent on cracking throughout that process is captured by calorimetry analysis. These results verify that grain boundaries play a key role in damage evolution during martensitic transformation and that microstructural control can extend the size‐scale of viable single crystal or oligocrystal SMCs from the micro‐ to the millimeter scale. [ABSTRACT FROM AUTHOR]

Forty years ago, Garvie and his Australian co‐workers reported that the stress‐induced transformation of metastable tetragonal zirconia grains to the monoclinic symmetry could give rise to a powerful toughening mechanism. Their results even led them to consider zirconia systems as analogues of certain steels. This seminal paper generated extraordinary excitement in the ceramic community and it is still the subject of extensive research. Transformation toughening is widely used in zirconia materials and results in an increase in strength and toughness when compared to nontransformable ceramics, but the implementation into strong, tough, and sufficiently stable materials has not been fully reached. Zirconia ceramics generally fail at low strains with a much larger scatter in the strength values than metals and require statistical approaches to failure. Here we describe in detail the mechanical behavior laws of ceria‐doped zirconia composites exhibiting a high degree of stress‐induced transformation. They present, to some extent, mechanical behavior analogous to a metal, displaying, (a) significant amount of transformation‐induced plasticity without damage, (b) very high flaw tolerance and (c) almost no dispersion in strength data. They potentially open new application avenues in situations where the advantages of ceramics were dampened by their brittle failure behavior. In particular, the consequences of such behavior for dental implants and additive‐manufactured structures are highlighted. [ABSTRACT FROM AUTHOR]

The present paper is devoted to the problem of sintering ceramics based on yttria-stabilized zirconia (Y-TZP). In this paper, we studied the effect of two obtaining methods (co-precipitation and technical hydrolysis) on sintering kinetics of Y-TZP nanopowders. We used the constant rate of heating (CRH) method at different heating rates for determining the sintering mechanisms. The basic mechanism and activation energy ( Q) of diffusion at the initial sintering stage were estimated using the sintering rate equations that are applicable to the CRH data. We found that nanopowder 3Y-TZP produced by the co-precipitation method (DIPE) was sintered according to the volume diffusion mechanism ( n = 1/2) and nanopowder TZ-3Y (TOSOH) produced by the technical hydrolysis was sintered according to the grain boundary diffusion mechanism ( n = 1/3). [ABSTRACT FROM AUTHOR]

The paper reports the data on the sensing properties of xCaO-(100-x)ZrO2 (CSZ, x=9, 12 and 15 mol.%) and 8Y2O3-92ZrO2 (YSZ) solid electrolytes, manufactured from nanosized lowagglomerated powder. Stabilized zirconia solid electrolytes (SE) were synthesized via the original co-precipitation technique and annealing at 1823K in air for 3 hours. Phase composition and conductivity of obtained ceramics was investigated via XRD and impedance spectroscopy techniques. Electromotive force (EMF) response on O2 partial pressure was obtained at 966K for sensors with stabilized zirconia membranes. The data obtained was compared with Nernst equation. The impact of the precursor powder synthesis technique on electrical and sensing properties was discussed. [ABSTRACT FROM AUTHOR]

This paper describes an efficient method of fabricating high-performance ceramic (HPC) parts by using solvent-based slurry stereolithography (3S) and sintering. In this study, zirconia was used as the structural material, methyl alcohol was used as the solvent, a waterborne inorganic pigment was used as the dispersant, and a visible-light-curing resin was used as the organic binder for forming the slurry. The slurry was photocured using a visible-light projector for layer-by-layer deposition in an enclosed cabinet to form a three-dimensional object. The obtained green part was sintered at high temperatures (up to 1600 °C) so that it densified and formed a rigid body. Thus, an HPC part with high material strength could be produced. A complete system was developed for producing complex zirconia ceramic parts with a high level of precision without the necessity of generating support structures for the overhang features. The system was determined to achieve a very fine-detailed shape (30 μm). The mechanical properties of the obtained zirconia parts, such as flexural strength, density, and average roughness, were also investigated in this study. [ABSTRACT FROM AUTHOR]

The 0.2Li2ZrO3-0.8MgO (Li2Mg4ZrO7) ceramics were prepared by conventional solid-state reaction method. The effects of lithium fluoride (LiF) addition on the microstructure, sintering temperature and microwave dielectric properties of Li2Mg4ZrO7 ceramics were investigated. The experimental results demonstrated a typical single phase existed in Li2Mg4ZrO7-LiF ceramics, in which LiF was proved to be an effective sintering aid for the Li2Mg4ZrO7 ceramic. LiF obviously lowed the optimum sintering temperature of Li2Mg4ZrO7 ceramic from 1500 to 1050 °C and improved the sintering ability of the matrix. In this paper, the microwave dielectric properties were strongly dependent on the amount of LiF additions and the sintering temperature. Optimum microwave dielectric properties (εr = 12.95, Q·f = 180,011 GHz and τf =− 23.51 ppm/°C) were obtained in Li2Mg4ZrO7-4 wt% LiF ceramics sintered at 1050 °C. [ABSTRACT FROM AUTHOR]

3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramics are promising restorative materials being extensively used for fabricating dental prosthodontics. However, peri-implant inflammation and the severe abrasive wear on occlusive natural teeth are two critical problems in the clinical application of zirconia dentures. The paper aims to improve the antibacterial and tribological performance of 3Y-TZP ceramics through laser surface texturing. Three types of surface textures, including micro-honeycombs, micro-composite grids, and micro-grooves, were fabricated onto the zirconia specimens. The effects of different microtextures on the surface behaviors, including wettability, bacteria adhesion, and wear behavior, of 3Y-TZP ceramics were rigorously studied. The results indicate that the introduction of microtextures can change the solid-liquid contact of the zirconia surface, thus affecting its wettability. Wettability is a decisive factor that determinines the antibacterial behavior of textured zirconia ceramics. A hydrophobic surface is more conducive to inhibiting the adhesion, extension, reproduction of bacteria and thus achieves a superior antibacterial performance. The examined microtextures yield the improvement of wear resistance for the zirconia ceramics, but their performances depend on the texture density and the structural strength. The results obtained can provide technical guidance for the design and application of microtextures in the restorative dental fields. [ABSTRACT FROM AUTHOR]

PURPOSE. This study assessed the effect of storage time on chemical structure of a single-bottle and a two-bottle experimental ceramic primer and micro-shear bond strength (µSBS) of composite to ceramic. MATERIALS AND METHODS. This study was conducted on 60 sintered zirconia and 60 feldspathic porcelain blocks. Half of the specimens (n = 30) were subjected to surface treatment with the single-bottle Clearfil ceramic primer (n = 15) and two-bottle experimental primer (n = 15) after 24 hours. The remaining half received the same surface treatments after 6 months storage in distilled water. Composite cylinders were bonded to the ceramics, and they were then subjected to µSBS test. Also, the primers underwent Fourier-transform infrared spectroscopy (FTIR) after 24 hours and 6 months to assess their chemical structure. Data were analyzed with 3-way ANOVA and adjusted Bonferroni test (alpha = 0.05). RESULTS. The µSBS of both ceramics significantly decreased at 6 months in one-bottle ceramic primer group (P = .001), but it was not significantly different from the two-bottle experimental primer group (P = .635). FTIR showed hydrolysis of single-bottle primer, cleavage of silane and 10-MDP bonds, and formation of siloxane bonds after 6 months. CONCLUSION. Six months of storage caused significant degradation of single-bottle ceramic primer, and consequently had an adverse effect on µSBS. [ABSTRACT FROM AUTHOR]

This study aimed to assess the suitability of printed zirconia (ZrO2) for adhesive cementation compared to milled ZrO2. Surface conditioning protocols and disinfection effects on bond strength were also investigated. ZrO2 discs (n = 14/group) underwent either alumina (Al2O3) airborne particle abrasion (APA; 50 µm, 0.10 MPa) or tribochemical silicatisation (TSC; 110 µm Al2O3, 0.28 MPa and 110 µm silica-modified Al2O3, 0.28 MPa), followed by disinfection (1 min immersion in 70% isopropanol, 15 s water spray, 10 s drying with oil-free air) for half of the discs. A resin cement containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) was used for bonding (for TSC specimens after application of a primer containing silane and 10-MDP). Tensile bond strength was measured after storage for 24 h at 100% relative humidity or after 30 days in water, including 7500 thermocycles. Surface conditioning significantly affected bond strength, with higher values for TSC specimens. Ageing and the interaction of conditioning, disinfection and ageing also impacted bond strength. Disinfection combined with APA mitigated ageing-related bond strength decrease but exacerbated it for TSC specimens. Despite these effects, high bond strengths were maintained even after disinfection and ageing. Adhesive cementation of printed ZrO2 restorations exhibited comparable bond strengths to milled ZrO2, highlighting its feasibility in clinical applications. [ABSTRACT FROM AUTHOR]

In dentistry, all ceramic restorations were widely used because of perfect esthetic, especially the zirconia ceramic. Now in digital dentistry, zirconia dental restorations are mostly made from digital manufacturing system such as the computer-aided design and computer-aided manufacturing (CAD/CAM) or three-dimension printing (3DP). After producing, the sintering process is indispensable due to the increase in the mechanical properties. Notably, the side effect of shrinkage of the sintering process is difficult to predict or control and cannot be studied deeply. Reflecting the accurate of zirconia restoration is lower, especially the most important factor of restoration fitness. So the poor fitness of restoration easily leads to secondary caries or micro leakage that the tooth will decay again and the remaining teeth will need to be removed completely. In this paper, the 3DP is the target manufacturing process to avoid the high cost of CAD/CAM processing; the 3DP product needs to be of high precision after the sintering process. However, the shrinkage of the 3DP product is difficult to predict and cannot be studied deeply. Therefore, different shrinkage rates of experimental pieces following the manufacturer's instructions of the sintering process are first predicted in CAE analysis, experimental design, and regression analysis. The results are then applied in the manufacture of incisor restoration to verify the shrinkage. This can make the restoration fit in the patient's mouth properly and reduce the medical operation time. It helps the 3DP to successfully apply the dentures. [ABSTRACT FROM AUTHOR]

The objective of this paper is to review the current knowledge on the development of nanostructured zirconia-based ceramics and composites suitable for application in dentistry. Isi Web of Science, Science Direct, Scientific.net databases, and Google were searched electronically for the period of 1980 to the present, matching the keywords "nano" with the keywords: "Zirconia, ZrO2, Y-TZP, and dental, dentistry". A total of 74 papers were found, with the majority coming from Asia, indicating a more active scientific interest on the topic in this geographic area, followed by Europe, South America, and North America. The research shows, even though the scientific activity on nanostructured ceramics was intense in the last fifteen years, the development of fully dense zirconia-based nanoceramics is yet at an initial stage, most of all from the point of view of the clinical applications. It has been demonstrated that nanostructured ceramics can show improved properties because of the reduction of the grain size to the nanoscale. This is also true for zirconia-based nanoceramics, where some improvements in mechanical, optical, as well as resistance in low-temperature degradation have been observed. Potential applications of this class of material in the dental field are discussed, summarizing the results of the latest scientific research. [ABSTRACT FROM AUTHOR]

Ceramics based on zirconium dioxide are very important compounds for dental, implant, and structural material applications. Despite the fact that tetragonally stabilized YSZ has been well studied, the search for new compositions of zirconia-based ceramics is still in progress. The ZrO2-CeO2 system is one of the alternatives for YSZ materials, but there is conflicting experimental data on its phase composition and mechanical properties depending on the ratio of components. In this study, we investigated the phase composition, and microstructural, mechanical, and physical properties of (1 − x)∙ZrO2-x∙CeO2 (step of x = 0.05) ceramics obtained by the solid-state sintering process from micron-sized powders. For the characterization of samples, XRD, Raman spectroscopy, SEM, the Vickers Microhardness Test, and dielectric spectroscopy were implemented. The results showed that by varying the CeO2 concentration, it is possible to synthesize stable tetragonal ZrO2 at room temperature with a high microhardness HV0.05 value of ~1500, low porosity (~2.5%), and a high dielectric constant of 36. The pronounced combined effect of tetragonal phase formation, densification, and grain size reduction on the mechanical and dielectric properties of the experimental samples was investigated. Refined experimental data make it possible to synthesize high-quality zirconia–ceria ceramics for use as refractories, dispersed nuclear fuel, or solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

The distribution of second phase particles in the microstructure of composite ceramics affects the mechanical properties, and the intragranular structures often result in better properties compared to the intergranular structures. However, it is difficult to obtain composite ceramics with intragranular structure by conventional route. To produce composite ceramics with an intragranular structure in a simpler route. In this work, starting powders with different phase compositions were obtained by the co-precipitation method, and zirconia toughened alumina (ZTA) composite ceramics were prepared with these starting powders by spark plasma sintering (SPS). The results show that it is easier to fabricate ZTA composite ceramics with an intragranular structure by using composite powders containing amorphous or transition phase Al2O3 as starting materials. The phase composition of the powder prepared by the co-precipitation method after calcination at 1100 °C is θ-Al2O3 and t-ZrO2, and the average grain size after sintering at 1500 °C is 1.04 ± 0.28 µm, and the maximum Vickers hardness and fracture toughness of the specimens reach 19.37 ± 0.43 GPa and 6.18 ± 0.06 MPa·m1/2, respectively. The ZrO2 particles were the core of crystallization and grow together with the Al2O3 matrix, forming the intragranular structure of ZTA ceramics. This work may provide a new idea for preparing composite ceramics with intragranular structure. [ABSTRACT FROM AUTHOR]

The paper presents the results of finite element analysis and experimental testing under simulated physiological loading conditions on issues shaping the functional properties of individual all-ceramic abutments manufactured by CAD/CAM technology. The conducted research have cognitive significance showing the all-ceramic abutment behavior, as a key element of the implantological system, under the action of cyclic load. The aim of this study was evaluation the fatigue behavior of yttria-stabilized zirconia abutment submitted to cyclic stresses, conducted in accordance with EN ISO 14801 applies to dynamic fatigue tests of endosseous dental implants. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of the electrical conductivity of tantalum-doped zirconia ceramics prepared by spark plasma sintering. In this study, the temperature dependence of conductivity in as-prepared specimens and in those previously annealed in air is determined and compared. A semi-empirical model, which is based on the oxidation states of the cations, has been developed and successfully assessed. According to this, the conductivity is basically controlled by the diffusion of tetravalent zirconium cations in both cases, although the concentration of these species varies drastically with the amount of induced oxygen vacancies. This is a quite unexpected fact, since conductivity is normally controlled by anionic diffusion in zirconia ceramics. This option is forbidden here due to the presence of substitutional pentavalent cations. Therefore, conductivity values are much lower than those reported in trivalent or divalent substitutional cation doped zirconia ceramics. [ABSTRACT FROM AUTHOR]

This paper presents the micro-shot peening of zirconia (ZrO)-advanced ceramics applicable for bio-medical, dental, automotive and aerospace sectors. A ZrO-advanced ceramic was micro-shot blasted with selected parameters as a first-step investigation focused on the topography, microstructure, surface hardness and the surface fracture toughness ( K) characteristics. A new technique of micro-blasting was conducted using a portable shot blaster. A white-light interferometer, scanning electron microscopy and Vickers indentation technique were employed for the analysis. This was followed by determining the K using an empirical equation. Surface roughness was improved by 34 % after micro-shot blasting treatment. No surface cracking was present which generally exists due to the brittle nature of the ceramic. The hardness, however, reduced by 5.6 % with a reduction in the Vickers crack length of 9 %. This improved the K by 3 % when comparing the micro-shot peened surface to the original, as-received surface. It is difficult to conclude if the ZrO-advanced ceramic has undergone plastic deformation and the movement of dislocations increased to strengthen the ZrO ceramic at this stage. However, based on the results, it can be predicted that a level of surface compression was induced beneath the micro-shot peened layer as indicated from the result of the surface topography and integrity. This would justify the hardness modification and the enhancement in K. [ABSTRACT FROM AUTHOR]

The paper discusses structure investigations of the zirconium oxide-multiwalled carbon nanotube composite produced by electrophoretic codeposition of the components. Thermal analysis, Raman spectroscopy, and TEM analysis have revealed the strong influence of multiwalled carbon nanotubes on the sintering kinetics of zirconium oxide, as well as the structure and phase composition of sintered ceramics. [ABSTRACT FROM AUTHOR]

Motivated by the prevailing assisted techniques in wheel grinding of brittle and hard materials, an attempt is made in this paper to identify the feasibility of robot-assisted abrasive belt grinding of zirconia ceramics. Owing to the flexible machining system, the challenge of this attempt resides in achieving the required profile accuracy and surface quality, in which the evolution of grinding-induced micro-cracks is prioritized. The single-grit scratching simulation based on an improved chip-thickness model that incorporates elastic modules of tool-workpiece engagement is employed to explore the damage mechanism in terms of the initiation, propagation and suppression of micro-cracks. The simulation results demonstrate that the critical depth of cut for brittle-to-ductile transition of zirconia ceramics is determined as 0.42 μm according to the tentative maximum undeformed chip thickness (UCT) values. In ductile-regime grinding, the zirconia surface morphologies are independent of the abrasive particle velocity. Lateral cracks begin to initiate especially when the maximum UCT exceeds 0.42 μm, and the brittle removal becomes dominant. In brittle-regime grinding, high abrasive particle velocity could help substantially enhance the workpiece surface integrity by suppressing the median/radial cracks that initiate once the maximum UCT approaches 0.8 μm. Experiment concerning the force-controlled robotic belt grinding of zirconia ceramics is conducted to verify the simulation results via the microscope observation of ground surface morphologies. The findings are likely to provide experimental evidence on the feasibility of belt grinding of brittle and hard materials with a flexible industrial robot. [ABSTRACT FROM AUTHOR]

Partially stabilized zirconia (PSZ) ceramics play a significant role as fundamental ceramics and refractory materials. In this work, a CaO-PSZ ceramics material was synthesized from fused ZrO 2 by microwave sintering. The stability properties and structural characteristics of the products were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that in a microwave field, the duration and sintering temperature presented similar influence trends for the stability properties of ZrO 2 ceramics materials, which the finding was assigned to the phase transformation of ZrO 2 with temperature change. In addition, following the microwave treatment of the fused zirconia sample at 1450 °C for 2.0 h, a cubic and monoclinic mixed phase was formed. These outcomes corresponded to the results from the SEM and energy dispersive X-ray (EDAX) analysis, demonstrating the successful preparation of the CaO-PSZ ceramics. The toughness of the ceramics was improved, which could be attributed to the formation of CaO-stabilizer-precipitated acicular crystals. The theoretical fundamentals and the practical cases presented in this paper are beneficial for the application of the microwave sintering technology in the synthesis of CaO-PSZ ceramics. [ABSTRACT FROM AUTHOR]

Previous studies have shown that an "intragranular" structure can greatly improve the properties of composite ceramics. In this paper, the influence of ZrO2 content changes and different preparation methods of the composite powder on the formation of the "intragranular" structure and mechanical properties of composite ceramics was investigated. The results showed that 3 vol% ZrO2–Al2O3 composite ceramics prepared by mechanical grinding and dispersing technology contained a large number of "intragranular" structures after microwave sintering at 1500 °C for 30 min, and its relative density, flexural strength, fracture toughness and Vickers hardness were 99.07%, 520.21 MPa, 7.64 MPa.m1/2 and 18.79 GPa, respectively. In addition, the flexural strength and fracture toughness were increased by 50% and 83%, respectively, compared with those of 3 vol% ZrO2–AlO3 ceramics prepared by the conventional direct doping ZrO2 powder method. The "intragranular" ZrO2 particles were dispersed in the Al2O3 ceramic matrix and formed a superlattice structure, and there was a coherent relationship between the two interfaces. The strengthening and toughening mechanism of the "intragranular" structure of ZrO2–Al2O3 composite ceramics is discussed. [ABSTRACT FROM AUTHOR]

Interest in composite ceramics based on oxide and nitride compounds is due to the combination of their structural, strength and thermophysical parameters. Moreover, in the case of composites based on xSi3N4 - (1-x)ZrO2, the strength parameters, as well as resistance to thermal expansion, are determined by the characteristics of zirconium dioxide, while the thermophysical parameters are determined by silicon nitride, for which the thermal conductivity values are almost an order of magnitude higher than for zirconium dioxide. The main method for production of composite xSi3N4 - (1-x)ZrO2 ceramics was the mechanochemical solid-phase synthesis method using high-speed grinding and thermal annealing, used to stabilize structural deformations caused by mechanical action. During the research, it was determined that a change in the ratio of ceramic components due to an increase in the contribution of Si3N4 in the composition leads to an increase in thermophysical parameters, the change of which is due to the higher thermal conductivity of silicon nitride. In turn, a change in thermophysical parameters, and as a consequence, an alteration in the rate of heat transfer due to phonon mechanisms, causes an elevation in resistance to external influences during thermal shocks. Experiments to determine resistance to thermal influences have shown that the presence of a high density of dislocations in the near-surface layer of ceramics contributes to a rise in resistance to temperature changes, alongside external mechanical influences, which is expressed in less pronounced trends in decreasing hardness indicators during heat resistance tests. [ABSTRACT FROM AUTHOR]

Two-component micropowder injection molding allows two different materials and, hence, two different functions to be integrated in one microdevice. This requires both components to be matched precisely. Therefore, high dimensional accuracy is essential in the successful development of a two-component micropart. This paper is about studies of the accuracy of the diameters of the inner hole of a gear wheel to be used as the first component of a shaft-to-collar connection. Diameters were measured in two defined directions, oriented 90° relative to each other. Items discussed are the size accuracy of green bodies and sintered specimens as well as the effects of different gating concepts. Sometimes, the inner hole is eccentric, depending on the gating concept employed. It was shown that a point-shaped gate can exert pressure on the feedstock nearby, thus causing deformation and reducing the diameter in these areas compared to the diameter in areas far from the gating system. The results also show that the eccentricity of the inner hole after sintering differs from that measured on green bodies, which is an indication of anisotropy in sintering. Moreover, the types of powder were seen to have an effect. [ABSTRACT FROM AUTHOR]

This paper reports on improvement of the physical and mechanical properties of Y2O3-ZrO2 ceramics through compositional optimization, the use of nanograined powders and utilization of microwave sintering. ZrO2 with 2-5 mol% Y2O3, prepared from nanopowders, was sintered in both conventional and microwave furnaces under exactly the same heating schedule. It was found that microwave sintering improves physical and mechanical properties of Y2O3-ZrO2 ceramics compared with conventional sintering. Compositions containing 2 mol% Y2O3 exhibit the greatest improvement due to retention of tetragonal ZrO2, with a 5% increase in relative density compared with conventional sintering. Grain size analysis indicated that there was significant grain growth in microwave sintered (MWS) samples (353 nm) compared with their conventionally sintered (CS) counterparts (200 nm) which is thought to be related to enhanced diffusional effects during microwave sintering. Associated with this was a 22% increase in Young's modulus to 220 GPa, a 77% increase in Vicker's Hardness up to 11.5 GPa and a 165% increase in biaxial flexural strength up to 800 MPa. Owing to the differences in physical and mechanical properties along with the altered phase assemblages produced, it is apparent that microwave heating provides an additional driving force during sintering which enhances diffusion processes. [ABSTRACT FROM AUTHOR]

In this paper, the densification of a ceramic powder matrix that contained large macropores of the size much larger than the average grain size of the matrix was studied. The grain-boundary diffusion controlled sintering models of ceramic matrix contained large macropores were first established. A sintering potential associated with the macropores was also verified and introduced into the models. The experimental data were collected for the sintering of porous 8 mol% yttria-stabilized zirconia system with 20 vol% large pores. The predictions of the model were found in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

The processing of yttria-stabilised zirconia (Y-ZrO2)-based ceramic nanocomposites by means of pulsed electric current sintering (PECS) is described. A nanometer-sized electrically conductive secondary TiCN phase was added to the insulating zirconia matrix in order to make the composite electrically conductive. The paper focuses on the importance of processing conditions and highlights the benefits of the PECS method as compared to more traditional hot pressing. The mechanical and microstructural properties of the ZrO2–TiCN composites have been determined, and the benefits of using an electrical current to densify these composites were explained in terms of the evolution of the electrical properties of the densifying powder compact. [ABSTRACT FROM AUTHOR]

In this paper, a water-based colloidal processing method for manufacturing multilayers with very thin zirconia layers between thick alumina-based layers is presented. The procedure involves the dip coating of green tapes in binder-containing slurries and further lamination and sintering. Dipping studies show that thickness increases with soaking time until a higher limit is achieved, indicating the existence of interaction between slurry and substrate. After sintering, homogeneous, dense, and continuous zirconia layers with thicknesses between 3 and 0.8 μm alternated with 350 μm layers of alumina are obtained, thus meaning that the cross section of these thin layers range from four or five to only one or two grains. Although the residual stresses are estimated to be around 2 GPa, indentation cracks do not shown any interaction when passing through the compressive layers, indicating the existence of a lower thickness limit to achieve a threshold stress. [ABSTRACT FROM AUTHOR]

Millisecond-pulsed Nd:YAG laser systems can be used for high-speed cutting of ceramics, due to the high average power available. However, due to the relatively long pulse duration (0.3–5 ms), millisecond laser-machining is predominantly a thermal, melt-eject process. The quality of the finished surface is limited by a redeposited melt and a heat-affected zone, in particular surface cracking. Shorter pulse duration lasers can provide a better surface finish but with a significantly longer processing time. This paper presents a method of improving the finish of millisecond-machined yttria-stabilized tetragonal zirconia polycrystal surfaces by postprocessing with a nanosecond-pulsed laser. Nanosecond machining was carried out directly onto the as-cut surface produced after millisecond processing, yielding a dramatic improvement of the surface finish in a relatively short time. [ABSTRACT FROM AUTHOR]

This paper reports a method of performing electrophoretic deposition (EPD) on non-conducting substrates overcoming the requirement of a conducting substrate through the use of porous substrates. The conductivity of the substrate is therefore no longer a limiting factor in the application of EPD. This method is applicable to the fabrication of thick or thin layers of ceramic or metal for various applications. As an example, thin and dense yttria-stabilized zirconia (YSZ) layers have been deposited on a non-conducting NiO–YSZ substrate by EPD from a non-aqueous suspension. A solid oxide fuel cell constructed on these sintered bilayers exhibited power densities of 384 and 611 mW/cm2 at 750° and 850°C, respectively. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells are currently constructed using a yttria stabilised zirconia electrolyte membrane. However, zirconia has a number of disadvantages associated with its use, such as the high operational temperatures required for it to exhibit acceptable levels of ionic conductivity. Alternative ceramics such as doped cerium oxide show promise as electrolytes capable of operating at reduced temperatures, but introduce additional problems such as electronic conduction and inferior mechanical properties. This paper describes the manufacture and characterisation of a number of prototype electrolytes consisting of a mixture of yttria stabilised zirconia and gadolinium doped ceria. Traditional ceramic processing techniques were used to produce the samples, which were then examined using dilatometry, impedance spectroscopy and X-ray diffraction. Results show a lowering of the ionic conductivity of zirconia with the addition of doped ceria. X-ray diffraction patterns obtained from the samples suggested that this effect could be attributed to the formation of a solid solution of ceria in zirconia. [ABSTRACT FROM AUTHOR]

The present paper discusses the complications that can arise in using in the core melt trap of the European nuclear reactor being designed a sacrificial material of 40% FeOx–60% SiO2 composition. The investigation of the interaction of zirconium dioxide ceramics with the sacrificial material has permitted the conclusion that at a local baring of the refractory layer its destruction can occur. The addition of neodymium oxide to the melts lowers erosion and excludes regeneration of the ceramics structure. [ABSTRACT FROM AUTHOR]

In this work, the structural, electrical, and mechanical properties and phase composition of high-content cubic zirconium oxide ceramics stabilized with Ca were investigated. The novelty of this work lies in evaluating the potential use of porous ceramics obtained using calcium carbonate as a matrix for dispersed nuclear fuel. Experimental samples were prepared using solid-phase synthesis through sintering in air at 1500 °C. The X-ray diffraction method and Raman spectroscopy showed that the fraction of the cubic zirconium oxide ZrO2-c phase gradually increased as the mass concentration changed from Cw = 0.00 to Cw = 0.15, and the CaZrO3 phase was present at concentrations of Cw = 0.20 and Cw = 0.25. When the phase composition was altered, significant changes occurred in the internal microstructure of the ceramics due to the processes of grain sintering and pore formation. Quantitative XRD analysis demonstrated the incorporation of Ca into the cubic structure of the ZrO2-c polymorph. Dielectric spectroscopy at low frequencies revealed that the synthesized ceramics had a dielectric constant of 16.8–22 with a low dielectric loss of ~ 0.005. The microhardness value at a load of 200 kgf (HV0.2) of the obtained samples varied between 5 and 12 GPa and depended on the internal microstructure and phase composition. The obtained results clearly indicate that the mechanical and electrical properties and phase composition of synthesized ceramics make them suitable as a matrix for dispersed nuclear fuels. [ABSTRACT FROM AUTHOR]

This review outlines the state of the art, processing techniques, and mechanical testing methods of zirconia (ZrO2)-based composites reinforced by carbon nanotubes (CNTs). The use of CNTs as a secondary phase in a zirconia matrix is motivated by their outstanding crack self-healing ability, the possibility to tailor the desired nano-structural properties, and their exceptional wear behavior. Therefore, a detailed investigation into CNT features has been provided. The debate of using the different Vickers indentation fracture toughness equations to estimate the resistance of crack propagation was critically reviewed according to crack characteristics. Finally, this review particularly highlights the exceptional role of ZrO2-based composites as a promising material owing to their outstanding tribo-mechanical properties. [ABSTRACT FROM AUTHOR]

Zirconia ceramics (ZrO2) have been used for a variety of applications due to their superior physical properties, including in machining tools and dentures. Nonetheless, due to its extreme hardness and brittleness in both sintered and half-sintered forms, zirconia is difficult to machine. In this study, half-sintered zirconia blocks are milled with tungsten carbide milling tools which arecoated with diamond film using hot filament chemical vapor deposition (HFCVD) at various substrate-to-filament distances. The objective was to determine the effect of substrate-to-filament distances on the coating thickness, diamond purity, coating grain size, and ZrO2 machining performance during HFCVD. The experimental results show that, in HFCVD, the grain size and coating thickness of the diamond film on milling tools tend to decrease when the substrate-to-filament distances decrease. Tool failure happened at a cutting time of 200 min for all coated tools. However, the machining quality in terms of surface topology, surface roughness, and tool condition is superior for diamond-coated milling tools with smaller grain sizes and thinner thicknesses. It can be concluded that diamond milling tools with a smaller grain size and lesser thickness produced under shorter substrate-to-filament distances have a superior machining performance and a longer tool life. This study could potentially be used for parameter optimization in the production of coated tools. [ABSTRACT FROM AUTHOR]

Due to its unique properties, zirconia is increasingly being used in dentistry, but surface preparation for bonding is difficult because of its polycrystalline structure. This study aimed to determine the effect of a new etching technique (Zircos-E) on Ceramill Zi (Amann Girrbach). The effect of etching and the use of primers (Monobond Plus and MKZ Primer) on the bond strength of zirconia with resin cement (NX3) was assessed. Shear bond strength was evaluated after storage in water for 24 h and after thermal aging (5000 thermocycling at 5 °C/55 °C). A scanning electron microscope (Hitachi S-4700) was used to evaluate the surface structure before and after the Zircos-E system. The roughness parameters were assessed using an SJ-410 profilometer. The etched zirconia surface is more homogeneous over the entire surface, but some localized forms of erosion exist. The etching of zirconia ceramics caused changes in the surface structure of zirconia and a significant increase in the shear bond strength between zirconia and resin cement. The use of primers positively affects the adhesion between resin cement and zirconia. Aging with thermocycler significantly reduced the shear bond strength, with one exception—sandblasted samples with MKZ Primer. Standard ceramic surface preparation, involving only alumina sandblasting, does not provide a satisfactory bond. The use of etching with the Zircos-E system and primers had a positive effect on the strength of the zirconium–resin cement connection. [ABSTRACT FROM AUTHOR]

Highlights • The generalized maximum tangential strain (GMTSN) criterion is revisited. • The influence of T-term on crack initiation angle and onset of fracture is studied. • Fracture behavior of CeO 2 -TZP disk specimens is predicted using the GMTSN criterion. • The results of the GMTSN criterion and classical fracture criteria are then compared. • Improved correlation with experiments is observed when using the GMTSN criterion. Abstract Ceria stabilized tetragonal zirconia polycrystal (CeO 2 -TZP) is one of the zirconia-based materials which is reported to have high fracture toughness and strong resistance to low temperature aging degradation (LTAD). Owing to the brittle behavior of CeO 2 -TZP, its fracture properties can be estimated using the concept of linear elastic fracture mechanics (LEFM). In this paper, the generalized maximum tangential strain (GMTSN) criterion is applied to predict the fracture initiation angles and the onset of fractures of CeO 2 -TZP disk specimens under mixed mode I/II conditions. It is found that the inclusion of T-term, the first non-singular term in strain solution, in the GMTSN criterion would yield significantly improved predictions of the experimental data obtained for CeO 2 -TZP disk specimens and reported in the literature. [ABSTRACT FROM AUTHOR]