Monolithic Ceramics Research Articles

Monolithic Ceramic Fixed Prosthetic Constructions In The Frontal Region

The most commonly used monolithic ceramics are lithium-disilicate and zirconium-dioxide ceramics. Lithium disilicate ceramics is the best choice for the reconstruction of front teeth because of the naturalness of the color and the translucency of the material. Zirconium-oxide ceramics have excellent mechanical properties and are most suitable for larger joint replacements in the area of strong dental forces. Case study of two patients. The first one has crowns made of monolithic lithium-disilicate ceramics in the frontal region, and the second patient has a crown made of monolithic translucent zirconium-dioxide ceramics. Monolithic fixed-prosthetic products successfully satisfy the patient's aesthetic and functional needs.

Bionic structural design and model calculation for high toughness Si3N4f/BNi fibrous monolithic ceramic: A strategy from the fibrous cell and interface

Preeminent mechanical and dielectric performances are demonstrated by covalently bonded Si3N4 ceramics, yet their application range is still challenged because of limited toughness and sintering density. In this work, the Si3N4f/BNi fibrous monolithic ceramic with uniaxially arranged Si3N4 fibers cells separated by BN interfaces were successfully synthesized via hot-pressed sintering based on bionic structural design. The Si3N4f/BNi fibrous monolithic ceramics with bionic structure exhibited flexural strength, fracture toughness, and density of up to 501 MPa, 10.99 MPa m1/2, and 3.43 g/cm3, respectively. The results revealed that bionic structural design enables to significantly increase the toughness of the ceramic without sacrificing its strength. Furthermore, an original model for determining the flexural strength of fibrous monolithic ceramics was proposed, which can account for various shapes of fibrous cells. The findings of this research open up new prospects for achieving competitive mechanical performance of ceramics.

Effect of machining environments on the crack behavior of ZrO2-Al2O3 composite during short-pulsed laser processing

The ZrO2-Al2O3 exhibits distinct behavior compared to monolithic ceramics when exposed to stress. The compelling quality of this trait makes it well-suited for any demanding supporting application that necessitates resilience. However, under a thermal process, it might cause functional concerns such as cracking patterns, which pose a threat to the endurance of orthopedic implants. This issue has lately attracted medical scrutiny. Being a thermal process, fiber laser treatment of ZrO2-Al2O3 is more complex than monolithic ceramic because of its unique thermal characteristics and varied rates of absorption, which rely on the matrix and the reinforcement material. This research aims to scrutinize the divergent characteristics of ZrO2-Al2O3 in terms of crack behavior while treating it with the same laser fluence under auxiliary environments. It has been found that ZrO2-Al2O3 prone to form cracks when processed under high-temperature environments due to the development of stress during phase transformation because of prolonged exposure, as evidenced by the surface characterization results. Meanwhile, when it was processed at low-temperature environments like water and ice, the detrimental effect of laser fluence factor appeared to be meager by reducing the likelihood of phase transformation and crack quantity. With this, the research demonstrates a promising approach that effectively maintains the overall structural integrity of ZrO2-Al2O3 by impeding the progression of the cracks along with a smooth, flawless surface during laser processing.

Fabrication of BiScO3–PbTiO3/epoxy 1–3 piezoelectric composites for high‐temperature transducer applications

Abstract1–3 piezoelectric composites are widely used in piezoelectric ultrasonic transducers due to their high thickness electromechanical coupling factor. However, the applications of the composites in high‐temperature fields are limited by the low heat resistance of both the piezoelectric and polymer phases. To tackle this, we designed and fabricated the BiScO3–PbTiO3/epoxy high‐temperature 1–3 piezoelectric composites. These composites exhibit a high thickness electromechanical coupling factor kt of 63%, a large piezoelectric coefficient d33 of 470 pC/N, and a pure thickness vibration mode. Furthermore, we fabricated a high‐temperature transducer based on the BiScO3–PbTiO3/epoxy 1–3 composites. The bandwidths of the composites measured in water and silicone oil (30% and 23%, respectively) are approximately 1.65 times greater than those of monolithic piezoelectric ceramics (18% and 14%, respectively). The bandwidth of the transducer can be increased to 78% by adding a porous alumina backing layer, with the working temperature reaching up to 300°C. The results indicate that the BS–PT/epoxy 1–3 composite is a potential candidate for high‐temperature transducer applications.

Novel synthesis of (Hf0.25Zr0.25Ti0.25Ta0.25)C-SiC biphasic ceramic micro-powders using single-source-precursor route

High-entropy carbides-SiC biphasic ceramics demonstrate outstanding mechanical and oxidation resistance properties. However, previous studies have predominantly focused on fabricating dense monolithic high-entropy carbides-SiC biphasic ceramics, with limited attention given to the production of high-purity, narrow particles size distribution high-entropy carbides-SiC biphasic ceramic powders. In this study, we successfully synthesized high-entropy carbides-SiC biphasic ceramic powders, specifically (Hf0.25Zr0.25Ta0.25Ti0.25)C-SiC, utilizing the polymer-derived-ceramic (PDC) route employing transition metal alcohol solution and methyltrimethoxysilane. The resultant powders exhibited an average particle size of ∼15 μm, with a narrow particle size distribution. Furthermore, variations in the heat treatment temperature demonstrated minimal impact on the particle size, while maintain compositional homogenous from nanoscale to microscale, and exhibiting low oxygen content less than 1.01 %. The introduction of the SiC phase also enhances the dynamic oxidation resistance of the high-entropy carbides. This pioneering work will not only provide a novel approach for obtaining other high-entropy carbides and SiC biphasic ceramic powder but also offers prospects for large-scale fabrication in industrial.

Experimental and numerical study on the ballistic performance of laminated ceramics

The ballistic performances of laminated ceramics were investigated experimentally and numerically and then compared with monolithic ceramics. Sixteen ceramic configurations were generated using two geometry types (hexagonal and square) and combination of three ceramic materials (Al2O3, SiC, and B4C). Depth of Penetration ballistic tests were employed to evaluate their ballistic performance. According to the results, monolithic ceramic has higher ballistic performance than all laminated ceramic combinations. In laminated ceramics, using thicker ceramic on the strike-face increases the ballistic efficiency more than using it on the backing face. In addition, when a backing-face ceramic is combined with a more efficient strike-face ceramic, the ballistic performance is better than combination of same ceramic material. Lastly, finite element analysis were performed to simulate some of the tested configurations having SiC ceramic type. A similar trend was observed between the simulations and the tests.

Warm Pressing of Organosilicon Polymer Toward Monolithic Ceramics

Warm pressing of organosilicon polymers is often challenging due to the formation of cracks due to release of volatile compounds during the warm pressing process. The focus of the present study is to warm press crosslinked SMP‐10 powders into crack‐free compacts and to pyrolyze them to get bulk SiC monoliths. Crack formation during warm pressing is addressed by optimizing the crosslinking temperature, and the loss of formability of the powders crosslinked at higher temperatures is overcome with the use of uncured polymer as a binder. The crosslinking temperature of the preceramic polymer plays a crucial role in developing crack‐free green bodies. The amount of binder used is varied to study its effect on the bulk density of the pyrolyzed product. The warm pressed green bodies pyrolyzed at 1400 °C result in the formation of bulk silicon carbide ceramics and are characterized using X‐ray diffractometer and FTIR spectroscopy. Warm pressing is performed at a lower temperature than reported in the literature, and this limits the incorporation of oxygen during the warm pressing.

A universal strategy towards the fabrication of ultra-high temperature ceramic matrix composites with outstanding mechanical properties and ablation resistance

Materials with both excellent mechanical properties and good ablation resistance are urgently needed for the applications of thermal protection system in extreme high temperature oxidizing environments. However, owing to the lack of efficient fabrication processes, the existing materials suffer from either insufficient mechanical properties or poor ablation resistance. Herein, we report a novel solid–liquid combination fabrication strategy that successfully achieves the efficient incorporation of ultra-high temperature ceramics into 3D continuous carbon fiber performs as well as rapid densification. The relative density of the green body approaches the cubic close packing of spherical particles. Using Cf/ZrB2–SiC as an example, the as-prepared composite exhibits outstanding mechanical properties with a flexural strength surpasses 600 MPa and an unprecedented work of fracture of 11,851 ± 838 J/m2, which is two orders of magnitude higher than that of the currently reported monolithic ultra-high temperature ceramics. Moreover, the high ZrB2 content endows the composites with excellent ablation resistance and is thus capable of maintaining long-term non-ablative conditions at 2500 °C. The strategy possesses remarkable universality and high design flexibility, providing a time-saving and cost-effective universal strategy for the on-demand design and fabrication of high-performance ceramic, carbon, metal, and polymer matrix composites.

Bonding Effectiveness of Saliva-Contaminated Monolithic Zirconia Ceramics Using Different Decontamination Protocols.

This research study investigated the effect of new decontamination protocols on the bonding capacity of saliva-contaminated monolithic zirconia (MZ) ceramics cemented with two different monomer-containing self-adhesive resin cements. Standardized tooth preparations (4 mm. axial height) were performed for eighty human maxillary premolars under constant water cooling system. Eighty monolithic zirconia crowns (Whitepeaks Supreme Monolith) (n = 8/10 groups) were manufactured by CAD-CAM. Specimens were kept in the artificial saliva at pH = 7.3 for 1 minute at 37°C except control groups. The specimens have not been prealumina blasted and grouped according to cleaning methods and resin cements: control groups (C) (no saliva contamination + GPDM + 4-META (N) (CN) and 10-MDP (M) containing resin cement (CM), alumina blasted (AL) + GPDM + 4-META (ALN) and 10-MDP containing resin cement (ALM), zirconium oxide containing universal cleaning agent (IC) applied + GPDM + 4-META (N) (ICN) and 10-MDP containing resin cement (ICM), pumice (P) applied + GPDM + 4-META (PN) and 10-MDP containing resin cement (PM), and air-water spray (AW) applied + GPDM + 4-META (AWN) and 10-MDP containing resin cement (AWM)). Monobond Plus was applied to all surfaces for 40 seconds before cementation. The thermal cycle was applied at 5,000 cycles after cementation. The crowns were tested in tensile mode at a speed of 1 mm/min. The mode of failure was recorded. SEM examinations were carried out at different magnifications. Data were analyzed using rank-based Kruskal-Wallis and Mann-Whitney tests. No significant differences were found between the surface treatments and between the two types of resin cements. Interaction effects between surface treatments and resin cements were found to be significant by two-way ANOVA analysis. ICM group resulted in significantly better bond strength results compared with CN. ICM was found to result in better bond strength results compared with PM. The combination of universal cleaning agent and 10-MDP containing resin cement had significantly the highest cementation bond strength values. The increasing order of mean tensile bond strength values of decontamination protocols was C < AW < P < AL < IC. The mean tensile bond strength of 10-MDP containing resin cement was slightly higher than GPDM + 4-META containing resin cement. Universal cleaning agents can be preferred as an efficient cleaning method with 10-MDP-containing cement after saliva contamination for better adhesive bond strength of 4 mm crown preparation height of monolithic zirconia ceramics.

Ablation performance and mechanism of fibrous monolithic ZrB2-SiC ceramics prepared by wet-spinning co-extrusion method under plasma flame

The fibrous monolithic structure exhibits extensive graded fracture as well as load redistribution upon fracture due to the unique layered microstructure, providing an effective way to toughen ceramic materials. In this work, fibrous monolithic ZrB2-SiC/SiCw (FZSw) and fibrous monolithic ZrB2-SiC/BN ceramics (FZB) were prepared by wet-spinning and co-extrusion method using SiCw and BN as the interfacial layer. The strengths, toughness, and the work of rupture of FZSw were 117 MPa, 3.9 MPa m1/2, 104 J/m2, while that of FZB were 103 MPa, 2.6 MPa m1/2, 98 J/m2, respectively. FZSw and FZB were subjected to 200 s plasma ablation tests under 12.84 MW/m2 and plasma flame above 3000 °C. The mass and linear ablation rates of FZSw after testing were -0.34 mg/s and -0.2 μm/s, respectively, and remain intact, showing non-ablation characteristics, while FZB underwent delamination and destruction. The introduction of SiCw interface layer improved the thermal conductivity of FZSw and reduced the surface temperature of FZSw. Higher oxidation temperature and higher SiC content of the SiCw interface layer result in a great quantity of SiO2, which effectively isolated oxygen from further erosion.

The metameric effect of monolithic zirconias with varying yttrium ratios.

To evaluate the metameric disparities among monolithic zirconia materials with differing yttrium compositions across various lighting conditions. Thirty-six square-shaped zirconia samples measuring 10 × 10 × 0.5 mm were prepared from monolithic zirconia materials with three different yttrium contents. A 0.2 mm thick layer of polymerized dual-polymerizable self-adhesive resin cement was created using a silicone mold with the same dimensions as the prepared zirconia specimens. To evaluate metamerism, color measurements were conducted using a spectrophotometer device on a neutral gray background in a color measurement cabinet that offers four different illumination environments. All samples underwent aging by subjecting them to 10000 thermal cycles using a thermal cycle tester. Following thermal aging, color measurements were taken once more, and the data were recorded using the CIE L*, a*, b* color system. Two-way ANOVA and Post-hoc Bonferroni tests were employed to analyze the data. It was observed that there was no statistical difference among the color measurements made in different illumination environments of the monolithic zirconia ceramics used to evaluate metamerism (P > .05). This observation remained consistent both before and after thermal aging. After thermal aging, the color of monolithic zirconia materials exhibited a tendency towards red and yellow hues, accompanied by a decrease in brightness levels. It can be stated that different illumination conditions did not affect the metamerism of monolithic zirconia materials, but there was a color change in monolithic zirconia materials after a thermal aging period equivalent to one year.

Surface treatment, liquid, and aging effects on color and surface properties of monolithic ceramics.

The purpose of this study was to investigate the effects of surface treatments, liquids, and aging on color, translucency, and surface properties of monolithic ceramics. Lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) ceramics (n = 135 each) were cut and divided into three groups [crystallization+glaze (single stage), crystallization-glaze (two stages), and crystallization-polish (two stages)]. One sample from each group was examined using scanning electron microscopy (SEM). Remaining samples were divided into four subgroups (distilled water, coffee, grape juice, and smoothie) (n = 11 each), stored for 12 d in the respective liquids, and thermally aged. One sample from each subgroup was analyzed using SEM. The color, gloss, and roughness values of the samples were analyzed after surface treatment (initial) and storage under different liquids+aging conditions. The initial data and both the aged data and data change values were analyzed using robust two- and three-way analyses of variance. The glazed groups exhibited smoother surfaces. Ceramic type and ceramic-surface treatment interactions affected the initial translucency parameter (TP) (P < .001) and the initial and aged roughness values (P ≤ .001). Surface treatment type affected the color change (P < .001), and ceramic type affected the aged TP values (P < .001). Type of ceramic, surface treatment, and their interactions affected both the initial and aged gloss (P ≤ .001) and TP change values (P ≤ .015). Surface treatment type and ceramic-surface treatment interactions affected the gloss change values (P ≤ .001). Although both ceramics and all surface treatments are clinically applicable, crystallization-glaze is recommended. When gloss and smoothness are important or when translucency is important, ZLS or LDS may be preferred, respectively.

Finite element simulation of mechanical properties of TaC-based core/graphite shell fibrous monolithic ceramics

Finite element simulation of mechanical properties of TaC-based core/graphite shell fibrous monolithic ceramics

Success rate of all-ceramic FPDs depending on the time of restoration between 2011 and 2023.

Studies about success of FPDs (fixed partial dentures) mostly include restorations built by different clinicians. This results in limited comparability of the data. The aim of this study was to evaluate complications of all-ceramic FPDs built by 1 dentist between 2011 to 2023. 342 all-ceramic FPDs were observed during follow-up care. 48 patients received 262 single crowns, 59 bridges and 21 veneers. Because of the different lengths of the bridges, units were defined as restored or replaced tooth. 465 units performed by the same dentist from Nov 2011 to Nov 2022 were included. Influencing factors "restoration", "construction", "abutment", "localization", "vitality" and "application period" were evaluated using Kaplan-Meier Analysis and Log-Rank Tests. 406 units (87.3 %) showed no complication. 7 correctable chippings (1.5 %) and 10 recementable decementations (2.1 %) occurred. Six decemented units got lost (1.3 %). 21 units failed due to fatal fracture (4.5 %). Crown margin complications, such as secondary caries, occurred in 15 units (3.2 %). Comparing the influencing factors resulted in higher complication rates of veneers (P < .001), of monolithic ceramics (P ≤ .050) and of molar-restorations (P = .047). The application period had no influence on the success and survival rate. Overall, all-ceramic FPDs showed good clinical results. Although less complications were observed with modern restorations, these more often led to complete failure. To generate evidence-based recommendations, further studies are needed to evaluate the mid- and short-term success and survival of current all-ceramic restorations.

Fracture resistance of binderless tungsten carbide consolidated by spark plasma sintering and flash sintering

Binderless tungsten carbide (WC) consolidated by spark plasma sintering (SPS) and electrical resistance flash sintering (ERFS) has emerged as a promising alternative to materials obtained by traditional sintering methods. In this study, we investigated the influence of SPS and ERFS techniques on the mechanical properties of binderless WC. Hardness, indentation fracture resistance and elastic modulus were compared and analysed with respect to the microstructure of the resulting material. The results show that SPS tungsten carbide is harder, stiffer and denser when compared to the material produced by ERFS. Nevertheless, the fracture resistance of SPS ceramics was limited due to the lack of macroscopic toughening mechanisms. Conversely, flash-sintered tungsten carbide, consolidated by ERFS, possesses unique biphasic WC/W2C microstructures that promote crack deflection and bridging toughening mechanisms. Additionally, flash-sintered materials exhibit a more ductile character and are characterised by a lower effect of the strain gradient on the material plasticity upon indentation. This study provides valuable insights into the mechanical properties of ultra-hard monolithic ceramics, such as WC, influenced by ultrafast/flash sintering techniques.

Improving Bond Strength of Translucent Zirconia Through Surface Treatment With SiO2-ZrO2 Coatings.

Translucent monolithic zirconia ceramics have been applied in dental clinics due to their esthetic translucent formulations and mechanical properties. Considering inherent ceramic brittleness, adhesive bonding with resin composite increases the fracture resistance of ceramic restorations. However, zirconia is a chemically stable material that is difficult to adhesively bond with resin. To investigate the influences of SiO2-ZrO2 coatings on adhesive bonding of zirconia and the surface characterization of those coatings. Translucent zirconia discs were classified into groups based on surface treatments: CT (control), SB (sandblasting), C21(SiO2:ZrO2=2:1), C11(SiO2:ZrO2=1:1), and C12 (SiO2:ZrO2=1:2) (n=10). Surface characterization of coatings on zirconia were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness assessment (Ra), X-ray diffraction (XRD), water contact angle (WCA), translucency parameter (TP), and shear bond strength (SBS). Two-way ANOVA for shear bond strength results and ANOVA for Ra and WCA were performed. SEM images revealed SiO2 islands on zirconia disks coated with SiO2-ZrO2. Surface roughness of C12, C11, and C21 groups was significantly larger than those of groups SB and CT (p<0.05). XRD results showed that phase transformation of zirconia disks was detected only in the SB group. In addition, SiO2-ZrO2 coatings reduced WCA. The translucency decreased only in group C21. Group C11 showed the highest shear bond strength under both aging conditions. SiO2-ZrO2 coating is a promising method to enhance the adhesive resin bonding of translucent zirconia without causing phase transformation of translucent zirconia.

Fabricating exotic boron carbide ceramics by shaker milling and reactive spark plasma sintering of B and C: Application to the elusive B6C

A route based on the shaker milling of B and C powders followed by reactive spark plasma sintering (SPS) of the resulting B+C powder mixture is presented for the fabrication of exotic boron carbide monolithic ceramics with controlled stoichiometry, and applied to the elusive B6C ceramics. Firstly, it is shown that shaker milling for only 1 h refines down to the nanoscale, mechanically activates, and intimately mixes the B and C powders, making the resulting B+C powder mixture far more sinterable. Secondly, it is shown that B and C react during the heating ramp of the SPS cycles, resulting in a fully dense superhard (∼30 GPa) boron carbide monolith with the desired stoichiometry (B6C in this case) and fine twinned-grain microstructure at an SPS temperature (1550 °C in this case) at which typical commercial B4C powders barely densify. This low-temperature densification is possible mainly due to the enhanced solid-state sinterability promoted by both shaker milling and structural ordering, with the exothermic heat released during the formation of the boron carbide contributing little. And thirdly, it is shown that there is an optimal SPS temperature above which the hardness of these exotic boron carbide monoliths decreases because there is less twinning hardening.

The Ablation Performance of Silicon Nitride/Boron Nitride Fibrous Monolithic Ceramics under an Oxyacetylene Combustion Torch.

In this study, Si3N4/BN fibrous monolithic ceramics were successfully prepared by wet spinning extrusion and hot pressing, and the effects on its ablation performance and microstructure were studied. The samples were burned in an oxyacetylene flame for 60 s × 30 to evaluate the ablation resistance. With the increase in ablation time, the fibrous monolithic ceramics exhibited specific mass and linear ablation rates, which show a trend of first increasing, then decreasing, and then increasing again. When the ablation time is 60 s × 10, 60 s × 20, and 60 s × 30, the mass ablation rates of the fibrous monolithic ceramics are 1 × 10-5 mg/s, -8.3 × 10-6 mg/s, -6.7 × 10-7 mg/s, respectively; the linear ablation rates are 4.7 × 10-5 μg/s, -1.2 × 10-5 μg/s and 1.7 × 10-6 μg/s. After 60 s × 30 of ablation, the surface oxides of the species are washed away by the oxyacetylene flame, revealing a porous coral-like structure with many cracks. A glass phase layer, predominantly constituted by sintering aids, envelops the Si3N4 ceramic surface on the ablated sample, serving as an effective barrier against additional ablation.

A step-by-step technique to create an ideal color match, form, and surface texture to all-ceramic restorations.

Although the presence of a chairside CAD/CAM system in the dental office saves time and cost, it deprives the dentist from the dental technologist' skills and experience. The dentist now has to gain and acquire knowledge and skills about how to finish, characterize, stain, and glaze ceramic restorations. The main objectives of this article is to teach novel and reproducible techniques for surface color, texture, glaze and polish for either the chairside or laboratory fabricated indirect ceramic restoration. A protocol for intraoral characterization of monolithic ceramics; the "Triple R" protocol for tooth color mimicking was followed. It consist of three steps: (1) "Recognize" tooth color shapes, (2) "Record" the present color shapes in the patient dentition by drawing a color map for the color shapes extension and determine which luster paste stain to be used for replicating them, and (3) "Replicate" intraorally the recorded color shapes guided by the adjacent natural teeth using low fusing ceramic pastes (shades and stains) for color shape replication. Also, the final touch technique was followed to shape, texture and final surface finish of dental restorations. It is composed of 5 basic levels which we call dental "micro-esthetics that define shape, texture, and surface luster. Following the steps of both; the "Triple R" protocol and the "FINAL TOUCH" technique will help to reproduce the final shade of the restoration to create the illusion of a natural tooth to the observer. This article shows how combining two practical methodologies to record and replicate both color shapes and surface texture of natural teeth may extend mimicking, that is, step by step natural tooth shade beyond the limitations of the available commercial shade guides.

A unique fiber laser processing of Z-A composite under dry, gas, liquid, and solid environments: A competitive ablation efficiency followed by surface analysis

Compared to monolithic ceramics, the Z-A composite exhibits distinct behavior when stressed. It serves to impede the propagation of the crack's endpoint and retains its structural integrity. This intriguing quality makes it a choice for any high-stress supportive application that necessitates robustness, particularly in the medical industry. However, the laser processing of Z-A is quite sophisticated than monolithic ceramic due to its different thermal properties and varying energy absorption rates that are contingent upon the reinforcing material and matrix. The current investigation outlines a unique approach called FLSDM (fiber laser step-down milling) to create the squircle pattern on Z-A (uniquely by laser) for possible implications as a bone scaffold. The present work has also paid close attention to the effectiveness of laser processing factors (LPFs) that might affect the efficacy of ablation under the disparate states of environments like dry, liquid, gas, and solid. Moreover, this article asserts experimental inquisitions for an extensive comparative study on a short-pulse laser ablation efficiency and laser-treated surface (LTS) analysis under disparate environments. The study examines various aspects such as laser-induced surface morphology, crack behavior, crystal structure, bonding pattern, and phase transformation. The current FLSDM methodology exhibits its suitability by offering a possibility for the adoptable configuration on the Z-A to meet scaffold requirements.