Ceramic Slab Research Articles

Mucins 5b and 7 and secretory IgA in the oral acquired pellicle of children with caries and caries-free children

ObjectiveThe objective of this study was to determine whether differences in the abundance of mucins 5b and 7 as well as secretory IgA exist in the oral acquired pellicle between children with active caries and caries-free children. DesignPellicle formation was performed for 10 min in-situ on ceramic slabs in the oral cavity of children (5–7 years of age) with caries (n = 15) and without signs of caries (n = 13). Furthermore, unstimulated saliva was collected. Concentrations of Muc5b, Muc7 and sIgA were measured in desorbed pellicle eluates and in saliva. ResultsSignificantly larger concentrations of Muc5b, Muc7 and sIgA were detected in the pellicle obtained from children with caries compared to caries-free children. However, in the salivary samples concentrations of mucins Muc5b and Muc7 as well as sIgA did not differ significantly between the two groups. ConclusionsAll three pellicle components Muc5b, Muc7 as well as sIgA could be identified as potential biomarkers for early childhood caries with high sensitivity and specificity. This could contribute to a better understanding of the different caries susceptibility in children.

Study of a thermal dispersion in buildings and advantages of ceramic coatings for the reduction of energy expenditure

Energy consumption in buildings is due to the low efficiency of thermal and electrical systems and the high rate of thermal dispersion of the building envelope, defined as one or more layers of material that separate the internal environment from the external environment of a building. Their function is to protect the internal environment from external agents such as cold, heat, moisture, rain, hail, snow, wind, light, sources of noise pollution and, based on the criticality of the place, air pollution. To reduce energy consumption, it is therefore necessary to act primarily on the building envelope, which should be designed and constructed with the aim of guaranteeing thermo-hygrometric comfort and reducing energy consumption (and consequently CO2 emissions). This means the ability to meet certain performance requirements without significantly impacting energy consumption, such as maintaining the environmental temperature during the wintertime and a better thermal comfort during the summer period. Therefore, when designing a new building or renovating an existing housing unit, technologies and materials must be used to improve the energy performance of the building. This work demonstrates that with the addition of a ceramic slab as external coating, the heat losses decrease by 42% with respect to a traditional wall configuration without any thermal insulator installed. As for the existing houses already equipped with an internal insulation or a coat, the addition of the ceramic slab results in decreases in thermal variation of 31 and 40% for the internal thermal coat installation and a post construction ready-to-use insulation, respectively.

Real Cyclic Load-Bearing Test of a Ceramic-Reinforced Slab

Ceramic-reinforced slabs were widely used in Spain during the second half of the 20th century, especially for industrial buildings. This solution was popular due to the lack of materials at that time, as it requires almost no concrete and low ratios of reinforcement. In this study, we present and discuss the results of a real load-bearing test of a real ceramic-reinforced slab, which was loaded and reloaded cyclically for a duration of one week in order to describe any damage under a high-demand loading series. Due to the design of these slabs, the structural response is based more on shear than on bending due to the low levels of concrete and the geometry and location of re-bars. The low ratio of concrete makes these slabs ideal for short-span structures, mainly combined with steel or RC frames. The slab which was analyzed in this study covers a span of 4.88 m between two steel I-beams (IPN400), and corresponds to a building from the mid-1960s in the city of Igualada (Barcelona, Spain). A load-bearing test was carried out up to 7.50 kN/m2 by using two-story sacks full of sand. The supporting steel beams were propped up in order to avoid any interference in the results of the test; without the shoring of the steel structure, deflections would come from the combination of the ceramic slab together with the steel profiles. A process of loading and unloading was repeated for a duration of six days in order to describe the cyclic response of the slab under high levels of loading. Finally, vibration analysis of the slab was also done; the higher the load applied, the higher the fundamental frequency of the cross section, which is more comfortable in terms of serviceability.

Performance comparison of Yb:YAG ceramics and crystal gain material in a large-area, high-energy, high average-power diode-pumped laser.

We compare for the first time the influence of different Yb:YAG gain media on the performance of a large-area, high average-power laser system with an output energy of up to 6 J. Monocrystalline slabs grown by a new technique without central growth defect are compared with ceramics. Small signal gain, maximum output energy and thermal lensing are compared for ceramic slabs with co-sintered amplified spontaneous emission (ASE) absorber cladding, monocrystalline slab with and without optically bonded ASE absorber cladding, and surface structured monocrystalline slabs. We show that these large monocrystals with optically bonded absorber cladding have similar performance to cladded ceramics, so far the only material for high-energy Yb:YAG lasers.

Study on Thermally Induced Crack Propagation Behavior of Functionally Graded Materials Using a Modified Peridynamic Model

Peridynamic (PD) theory is used to study the thermally induced cracking behavior of functionally graded materials (FGMs). A modified thermomechanical peridynamic model is developed. The thermal crack propagation of a ceramic slab in quenching is calculated to validate the modified PD model. The results predicted by the modified PD model agree with previously published numerical and experimental ones. Compared with the original PD model, the calculation accuracy of the modified PD model for thermal cracking is improved. The thermal cracking in FGMs is also simulated. The effects of material shape, initial temperature, and ceramic fracture toughness on thermal crack propagation behaviors are studied. It can be found that the thermal cracks in FGMs are still in periodical and hierarchical forms. The metal materials in FGMs can prevent crack initiation and arrest the long cracks. The crack number tends to be increased with the increasing initial temperature, while the strengthened ceramic fracture toughness can decrease it.

A Triple-Layer Electromagnetic Heat Exchanger With Plane Poiseuille Flow: Control and Local Onset of Thermal Runaway

An electromagnetic (EM) heat exchanger (HX) is a device which converts EM energy into a usable form of heat. In this article, we present a 2-D multiphysics model mimicking the operation of a layered EM HX and simulating the nonlinear interaction between EM wave propagation, energy transport, and fluid flow. A triple-layer geometry of the EM HX represents a lossy ceramic slab surrounded by two channels with a plane Poiseuille flow of a lossless coolant. Validation of the model developed in COMSOL Multiphysics is done by comparing the results with the output of another numerical model, which uses a second-order implicit–explicit scheme where advective and diffusive terms are treated implicitly and the nonlinear heat source is treated explicitly. Layer thicknesses are chosen such that an electric field resonance is achieved in the central layer. Because of the resonance, a power response curve is found to be a double S-curve. We show that EM HXs operating on the middle branch of the double S-curve are favorable and efficient compared to the those operating on the lower or upper branch. Careful examination of transient evolution of temperature confirms that thermal runaway occurs when the local maximum temperature reaches a critical value. The model predicts a hotspot in ceramic region when thermal runaway initiated locally. We generate power response curves for increasing Peclet numbers, which is defined as the ratio of heat convection to conduction within the fluid region, and show that temperatures of upper and middle branches keep dropping with Peclet numbers.

6.2 kW quasi-continuous-wave diode-pumped Yb:YAG ceramic slab laser

We demonstrate a high power quasi-continuous-wave (QCW) diode-pumped Yb:YAG ceramic slab laser. The wavefront distortion of the assembled large-sized Yb:YAG ceramic slab module is evaluated firstly. Through a short cavity setup, the average output power of a single ceramic slab laser oscillator is up to 6.2 kW. The corresponding optical-to-optical efficiency with respect to the absorbed pump power is 64.8% and a slope efficiency of 72.1%, operating at a pulse duration of 560 μs and a repetition rate of 160 Hz. To the best of our knowledge, this represents a highest output power for a QCW Yb:YAG ceramic single slab laser oscillator ever reported to date. This result proves the way to the further development of high power solid-state Yb:YAG ceramic slab laser.

Opportune inward waste materials toward a zero waste ceramic slabs production in a circular economy perspective

AbstractThis work is related to the preliminary lab‐scale preparation of ceramic slabs, reproducing the characteristics of natural stones, containing up to more than 40 wt.% of different waste materials, namely laboratory glass, cullet glass (both thought as fluxing agents replacing feldspar), and ceramic waste obtained from drying squaring operations (for partial quartz sand replacement). Indeed, in order to pursue the circular economy principles, the possibility of turning different kinds of wastes into resources for the ceramic industry, surely represents the first concern to be addressed and demonstrated, with also the aim to reduce the environmental impact associated with landfill, minimizing manufacturing cost and contributing to preserve nonrenewable natural resources, which are known to be consistently depleted by the ceramic industries.

Size effect of thermal shock crack patterns in ceramics: Insights from a nonlocal numerical approach

A new weakly coupled thermoelastic ordinary state-based peridynamic (SB-PD) model considering strain-softening characteristics is developed to investigate the size effect on thermal shock crack patterns of ceramic slabs in water quenching tests. In the new weakly coupled thermoelastic ordinary (SB-PD) model, the general SB-PD model is derived by considering thermal effects. The new microscopic thermal conductivity that establishes the relationship between the microscopic geometries and macroscopic geometric conditions is derived from the analytical temperature distributions. Moreover, the new general form of the critical stretch takes the peridynamic state into consideration and is presented based on an equivalent energy relationship in which the softening tensile parts are taken into consideration. The numerically predicted thermal shock crack patterns are in good agreement with previous experimental observations, which demonstrates that the new nonlocal model is effective in capturing thermal shock crack patterns in cold quenching tests. Moreover, differences from the effects of the brittle ceramic specimen size and the water quenching temperature that affect the energy evolution and crack propagation speed during thermal shock fracturing processes are investigated.

Fabrication and microstructural characterizations of lasing grade Nd:Y2O3 ceramics

AbstractTransparent 0.6 at% Nd:Y2O3 ceramics were fabricated by vacuum sintering at 1550°C and hot isostatic pressing (HIP) at 1540°C. The ceramics sintered at such temperatures had good homogeneity with dense microstructures, without any residual pores and secondary phases. The in‐line transmittance reached 81.6% at 1000 nm and remained 81.1% at 650 nm. Continuous wave (CW) laser operation of an uncoated ceramic slab was evaluated. A maximum output power of 3.6 W with slope efficiency of 45.2% at 1.08 μm was obtained.

Fabrication, microstructure and optical properties of large-sized Nd:YAG and composite Yb:YAG transparent ceramic slabs

Abstract Large-sized Nd:YAG and composite Yb:YAG transparent ceramic slabs of high quality were fabricated by the conventional solid-state reaction sintering technique. The Yb:YAG transparent ceramic slabs were surrounded by undoped YAG transparent ceramics and this composite structure was built in the process of ceramic shaping. The difference in microstructure between Yb:YAG and YAG transparent ceramics was not observed and the composite Yb:YAG slabs showed fully dense and pore-free microstructure. The in-line transmittances at 400 nm reached 81.7% and 79.7 % for YAG and Yb:YAG transparent ceramics, respectively, indicating good optical quality of the composite ceramic slab. And the optical transmission micrograph was very homogeneous with only a few isolated scattering centers. These results suggested that building composite structure in the process of ceramic shaping was a simple and reliable technical scheme. Moreover, the large-sized Nd:YAG transparent ceramic slab with size of 150.0 mm × 50.0 mm × 4.0 mm was also prepared. The calculated absorption coefficient was about 0.002 cm-1 @1064 nm, which suggested that the optical quality of this Nd:YAG transparent ceramic slab had reached the level of Nd:YAG crystals.

Kinematics optimization of the polishing process of large-sized ceramic slabs

Although large-sized ceramic slabs have become a common market product nowadays, their finishing processes still lack proper analyses and optimizations. The finishing is carried out on energy-consuming polishing machines by a train of rotating abrasive heads, which oscillates in a transverse direction on translating slabs. In this paper, a computational method able to investigate the effect of the kinematics on the texture distribution is proposed. Its algorithms allow to map the number of contacts and the scratching angles, relevant factors in the definition of the polished surface quality, but also, differently from the previous studies, the easy use of any preferred law of motion. After validation, the method is applied to a traditional polishing machine in order to assess the optimal process parameters as the forward motion of the conveyor belt and the transverse oscillation of the beam carrying the rotating head with the fickerts. An enhancement in terms of surface quality and machining process is evident. In particular, results suggest to adopt a specific frequency value for the transverse motion, nearly the half of the original one: in spite of a very similar texture, a significant reduction of energy is permitted. Finally, the optimization of motions and processes may lead to other general benefits, such as a reduction of the tool wear and mitigation of possible issues as mechanical vibrations or noise.

Istraživanje keramičkih procesa numeričkim pristupima

The considerable increase in computers performance has led in recent decades to a growing diffusion of numerical modelling as a valuable tool to support the manufacturing industry. Among the industrial sectors that may take advantage of this methodology there is the ceramic one. In fact, the production of large format ceramic slabs have introduced new technological challenges in a sector already subject to complex product-development procedures, often based on a trial and error approach. For this reason, numerical simulations have become an actual and attractive method to overcome practical limitations and give a deeper insight into each phase of the production process. In this paper, advanced application of numerical modelling applied to the ceramic industry are presented, with special consideration for the production of ceramic slabs. Advantages and limitations of the adopted numerical techniques are discussed.

Fractal characterization of ceramic crack patterns after thermal shocks

AbstractThis work utilized a combination of experimental evidence and fractal geometric method to assess the effect of crack extension concerning the thermal shock on residual strength of ceramics. Sintered alumina (Al2O3) ceramic slabs were bundled and quenched in water under different thermal shock temperatures. The fractal dimension of thermal shock crack patterns on the interior surface and the cooled surface was calculated by the Box‐counting method. Fracture energy of a fractal pattern of microcracks in quasi‐brittle solids was employed to explain the relationship between crack length and fractal dimensions. The results show that if the crack propagation has the same crack length but a larger fractal dimension, it will absorb more fracture energy. The thermal shock crack patterns of Al2O3 ceramics with different grain sizes were analyzed, and the smaller grain size ceramic had a higher fractal dimension of crack patterns than the larger one.

Submicron‐grained Yb:Lu2O3 transparent ceramics with lasing quality

AbstractWe report on our recent progress of fabricating Yb3+‐doped Lu2O3 transparent ceramics for 1 μm solid‐state laser application. Well‐dispersed 3.3 at.% Yb:Lu2O3 nanopowders were synthesized using a co‐precipitation method. Without using any sintering aids, the Yb:Lu2O3 nanopowders could be densified by vacuum sintering at 1500°C/10 hours followed by HIPing at 1480°C/4 hours. Such obtained Yb:Lu2O3 ceramics had not only dense microstructure and submicron grain size of about 0.6 μm, but also in‐line transmission of 80.0% at 600 nm. Preliminary continuous wave (CW) laser experiments with an uncoated Yb:Lu2O3 ceramic slab have demonstrated highly efficient CW laser oscillation at 1079.8 nm.

Fabrication andkW‐levelMOPAlaser output of planar waveguideYAG/Yb:YAG/YAGceramic slab

AbstractUsing the tape casting method combined with vacuum sintering and hot isostatic pressing, high‐quality planar waveguideYAG/10 at.%Yb:YAG/YAGceramics were successfully prepared. For the sample presintered at 1750°C for 30 hours and thenHIPed at 1700°C for 3 hours in 200MPa argon, the in‐line transmittance reached 82.5% at 400 nm and the average grain size was ~17.1 μm. The diffusion behaviors of Yb ions across the contact boundary between the claddingYAGlayer and the core Yb:YAGlayer were determined by Fick's second law. Then, a 1030 nm continuous‐wave (CW) Yb:YAGplanar waveguide ceramic laser based on the structure of master oscillator power amplification (MOPA) was realized. After a single‐pass amplification, the maximum output of the ceramic slab (60 × 10 × 1 mm3) reached 1251 W and the corresponding optical‐to‐optical efficiency was 30.0%, which is the highest output power of a Yb:YAGplanar waveguide ceramic laser to the best of our knowledge.

Assessment of conversion efficiency of Cr4+ ions by aliovalent cation additives in Cr:YAG ceramic for edge cladding

Abstract0.25at.% Cr:YAG ceramics were successfully fabricated as the edge cladding of Yb:YAG transparent ceramic slabs through vacuum sintering of co‐precipitated powders, using oxide additives to introduce different cations. The effects of various cation additives (Si4+, Ca2+, and Si4+ + Ca2+) on the conversion efficiency of Cr4+ ions and optical characteristics of the Cr:YAG edge cladding were investigated. Measurements of the absorption spectra of the Cr:YAG ceramics without any additives revealed 2 absorption bands centered at 430 nm and 600 nm, which imparted the sample with a green color. The introduction of only Si4+‐bearing additive did not promote the transition of Cr ions from the 3+ to 4+ state. Theoretical analysis and experimentation revealed that the addition of CaO not only enhanced the microstructure and improved the transmittance of the Cr:YAG ceramic, but also introduced vacancies that assisted in the formation of Cr4+ ions. It was determined that CaO has the same effect on the conversion efficiency of Cr4+ ions whether it is added as a single additive or in combination with SiO2. The underlying mechanisms by which these aliovalent cation additives influence the formation of Cr4+ ions and affect optical properties are discussed in detail. High quality composite ceramics with Yb:YAG transparent ceramic slabs and dark brown‐colored Cr4+: YAG ceramic edge cladding were achieved through the addition of 0.05 wt.% CaO to the edge cladding, with no interfacial effects between the 2 regions being observed.

Femtosecond Yb:YGAG ceramic slab regenerative amplifier

We present a femtosecond regenerative Yb:YGAG (Y3Ga2Al3O12) ceramic slab amplifier delivering 405 fs pulses at a wavelength of 1030 nm with a bandwidth limit of 306 fs, 1.1 W of average power, 8 μJ of pulse energy, and a repetition rate of 100 kHz. The amplifier is seeded by 9 pJ pulses generated by a Yb-doped fiber ring oscillator with extra-cavity spectral shaping to minimize gain narrowing. The net-gain of the pulses is 60 dB, the spectral bandwidth is 4.1 nm (FWHM), and the M2 beam quality factor is < 1.2. Due to similar optical and thermo-mechanical properties to Yb:YAG, the Yb:YGAG gain medium is a promising alternative for upgrading the existing Yb:YAG picosecond disk amplifiers to the femtosecond regime.

Structural and Morphological Evaluation of Presintered Zirconia following Different Surface Treatments.

The aim of this study was to evaluate the effect of different surface treatments on roughness, grain size, and phase transformation of presintered zirconia. Surface treatments included airborne particle abrasion (APA) before and after sintering with different particles shape, size, and pressure (50 μm Al2O3, 50 μm glass beads, and ceramic powder). Thirty-five square-shaped presin-tered yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic slabs (Zenostar ZR bridge, Wieland) were prepared (4 mm height × 10 mm width × 10 mm length) and polished with silicon carbide grit papers #800, 1000, 1200, 1500, and 2000 to ensure identical initial roughness. Specimens were divided into five groups according to surface treatment: group I (control): no surface treatment; group II: APA 50 μm Al2O3 after sintering; group III: APA 50 μm Al2O3 particles before sintering; group IV: APA 50 μm glass bead particles before sintering; and group V: APA ceramic powder before sintering. Specimens were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) analyses, and tested for shear bond strength (SBS). Data were statistically analyzed using one-way analysis of variance (ANOVA) followed by post hoc tests for multiple comparisons Tukey's test (a > 0.05). Air abrasion before sintering significantly increased the surface roughness when compared with groups I and III. The highest tetragonal to monoclinic (t-m) phase transformation (0.07%) was observed in group III, and a reverse transformation was observed in presintered groups (0.01%). Regarding bond strength, there was a significant difference between APA procedures pre- and postsintering. Air abrasion before sintering is a valuable method for increasing surface roughness and SBS. The abrasive particles' size and type used before sintering had a little effect on phase transformation. Air abrasion before sintering could be supposed to be an alternative surface treatment method to air abrasion after sintering.

Strain-Stress Formation and Deformation of Molded Materials by Drying-Induced Shrinkage

Drying-induced strain-stress and deformation was modeled for molded materials such as ceramics and foods. The transient three-dimensional problem of strain-stress and heat and moisture transfer was solved simultaneously by the finite element method. The behaviors of internal strain-stress formation and deformation are compared among three modes of hot air heating, intermittent heating and internal heating for a ceramic slab. The concepts of the mass transfer potential and a linear viscoelasticity were introduced to consider the different sorption isotherm for layered foods consisting of two ingredients and creep phenomenon. The tensile and compressive stresses fluctuate and fall remarkably during lower heating period when the slab is heated intermittently. In the internal heating mode, drying proceeds fastest as well as stress formation is maintained at the lowest level in the three modes. This effectiveness of the internal heating is investigated experimentally by employing the microwave heating as well. The combination of different foods influences significantly not only the drying characteristic but also the internal strain-stress generation. The drying behavior could be analyzed with a high accuracy even if only heat and moisture transfer were solved without strain-stress analysis. This fact results in that heat and mass transfer and strain-stress are not always necessary to be analyzed simultaneously for saving the CPU time.