Bending strength of ceramic compounds bonded with silicate-based glass solder

In the field of dental technology, the length of ceramic pontics is limited to avoid mechanical failure. To reduce thermal-induced residual stress within the ceramic, using smaller subcomponents and subsequent bonding with silicate-based glass solder may be a favorable approach. Thus, the bending strength of zirconia compounds bonded with different silicate-based glass solders was investigated. For this purpose, rectangular specimens made of zirconia were bonded by glass solder. Parameters such as the scarf angle (45° and 90°), two different glass solders, as well as the soldering process (pressure and surface treatment) were varied. All specimens were subjected to quasi-static four-point bending tests according to DIN EN ISO 843-1. Additionally, the quality of the glass solder connection was evaluated using μCT and fractography. In the present study, zirconia compounds were sucessful bonded of zirconia compounds using silicate-based glass solder was. No significant differences in terms of bending strength were observed with respect to the different bonding parameters analyzed. The highest bending strength of 130.6 ± 50.5 MPa was achieved with a 90° scarf angle combined with ethanol treatment of the specimens before soldering and an additional application of a pressure of 2 bars in a dental pressure pot before subsequent soldering. Nevertheless, the bending strengths were highly decreased when compared to monolithic zirconia specimens (993.4 ± 125.5 MPa).

Novel hydrogen chemisorption properties of amorphous ceramic compounds consisting of p-block elements: exploring Lewis acid-base Al–N pair site formed in-situ within polymer-derived silicon-aluminum-nitrogen-based system

This paper reports on the relationship between the H2 chemisorption properties and reversible structural reorientation of the possible active site around Al formed in-situ within polymer-derived ceramics (PDCs) based on...

Resistance of High-Tc Superconductors: Review Article

"The origin of resistance and its relation to the superconducting mechanism remain a profound, unsolved mystery. Currently, model parameters used to fit normal state properties are specific and vary arbitrarily from one doping. This short review illustrates the electrical resistivity of ceramic high temperature superconductors copper oxides. The article gives a summary of the prevailing arguments of researchers to relate the material to ceramic HTS compounds. Keywords: superconductivity, HTC ceramic compounds, resistivity. "

Fabrication of Refractory Materials from Coal Fly Ash, Commercially Purified Kaolin, and Alumina Powders

Coal fly ash and kaolin are ceramic compounds utilized as raw materials in the production of refractories. Fly ash is an environmental pollutant that emanates abundantly from coal thermal power plants. The management of the large amounts of fly ash produced has been very challenging, with serious economic and environmental consequences. Kaolin, on the other hand, is a natural and synthetic clay material used in medicines, paper, plastics, and cosmetic preparations. In this research, refractory materials (cordierite (Mg2Al4Si5O18), mullite (3Al2O3·2SiO3), and kyanite (Al2SiO5)) were fabricated in four different experiments, and an assessment was made of the strength of each of the materials. Coal fly ash and kaolin were each blended with alumina as starting materials. MgO and AlF3·3H2O were each applied as additives to the reacting materials. The mixtures were molded and sintered at temperatures between 1000 °C and 1200 °C for three hours in a muffle furnace, and characterized by SEM and XRD. The analysis revealed the evolution of cordierite, mullite, and kyanite alongside other crystalline compounds. The formation of kyanite in experiment C, due to the addition of AlF3·3H2O, is unprecedented and phenomenal. The XRD figures show the corundum phases crystallize at 1100 °C in experiments A and B, and disappear at 1200 °C.

Investigation of Thermal Behavior of 3D PET Knits with Different Bioceramic Additives

The purpose of this study is to investigate the thermoregulatory properties of polyethylene terephthalate (PET) 3D knitted materials with bioceramic additives which are highly absorbing far-infrared (FIR) radiation. Ceramic materials are well-known and useful for thermal insulation applications. In order to compare different types of ceramic additives and coating methods for their incorporation into textile, several types of ceramic compounds with heat-retaining function were selected: germanium (Ge), aluminum (Al) and silicon (Si) additives were applied by impregnation in squeezing padder and titanium (Ti) by the screen printing method. The thermoregulatory properties (thermal resistance, heat-retaining effectiveness and air permeability) of 3D PET knits with bioceramic additives were estimated. In this study scanning electron microscopy (SEM) images were used to analyze the morphology of coated fabrics, X-ray fluorescence spectroscopy (XRF) analysis was applied to evaluate the number of minerals with high heat capacity in each formulation used for treatment. The knits coated with a formulation containing Ti ceramic additives demonstrated the most effective thermal behavior. Furthermore, better heat accumulation effectiveness of Ti ceramics containing knits was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. It was also determined that 3D knitted fabric with Ti ceramic additives showed the highest emissivity among tested samples and the implication is that this sample radiates its energy more efficiently than others.

EXPERIMENTAL STUDY ON RADIOACTIVE WASTE IMMOBILIZATION IN LOW-TEMPERATURE MAGNESIUMPOTASSIUM PHOSPHATE CERAMIC MATRIX

Results of the studies carried out in NSC KIPT on application of magnesium-potassium phosphate ceramic matrices for immobilization of cesium, clinoptilolite with a cesium and solidified simulators of highly-active waste with high salt content are presented. The high radiation stability and corrosion resistance of the magnesiumpotassium phosphate ceramic matrices to leaching of radionuclide simulators, as well as basic components of solidified ceramic compounds were determined. It was shown that magnesium-potassium phosphate matrices for the solidification of liquid radioactive wastes of low and middle activity level, including waste with increased salt content, can be used in Ukrainian NPPs.

Ablation Behavior of Silicone Rubber-Benzoxazine-Based Composites for Ultra-High Temperature Applications

A novel type of silicon rubber composite with benzoxazine resins (BZs) and ZrO2 was prepared. The ablative response of the composites was investigated. The results showed that the composites with BZs had superior thermal stability and higher resides compared to the pristine composites. The linear ablation rate of the composites decreased significantly with the increase in ZrO2 content. The maximum back-face temperature of the burnt samples was no more than 100 °C for the obtained composites. Three major ablation processes were carried out simultaneously during the ablation processing. These mainly involved the carbonization of the composite, and the formation of ceramic compounds such as SiC and ZrC, as well as the shielding effect of the ablated layer, which subsequently enhanced the ablation resistance of the composites.