Influence of CeO2 addition on the microstructure and mechanical properties of Zirconia-toughened alumina (ZTA) composite prepared by spark plasma sintering

In this study, zirconia-toughened alumina (ZTA) samples with different amounts of CeO₂ were prepared by the spark plasma sintering method. The phase composition and microstructure of the samples were examined by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The addition of CeO₂ results in grain refinement and density increase; moreover, CeO₂ stabilises the high-temperature metastable phase. As the amount of CeO₂ reaches 7 wt%, a new CeAl₁₁O₁₈ phase appears. The Vickers hardness, modulus, and fracture toughness of the samples depend to a large extent on the grain size, relative density, and existence of the second phase. Among the composites, that with 5 wt% CeO₂ shows the best performance with the highest values of relative density, Vickers hardness, and fracture toughness: 96.51%, 1688 HV, and 9.91 MPa.√m, respectively.     

The capability of hibonite elongated grains to influence physical,microstructural, and mechanical properties of zirconia toughened alumina–CeO2–MgO ceramics

This work investigated the capability of hibonite (CaAl₁₂O₁₉) phase on structure and microstructure of zirconia toughened alumina–CeO₂–MgO ceramics. Three different additives (CeO₂, MgO and CaCO₃) were introduced into zirconia toughened alumina ceramics prepared by solid state reaction. X-ray diffraction and FESEM analyses were employed to observe the role of secondary phases especially hibonite and its influence on the microstructural features and other properties. Among the secondary phases present, EDX analysis revealed that hibonite phase contributed to elongated grains. Vickers indentations hinted a strong difference in the efficiency of compositional adjustment among the composites. The excellent Vickers hardness and fracture toughness results obtained for 3 wt.% CaCO₃ additions showed the appearance of 5.9% hibonite with the value of 1485 HV and 7.10 MPa·√m, respectively.     

Troubleshooting forum

Plastics Additives & Compounding has collaborated with the online expert solutions provider SpecialChem - specialchem.com - to bring you a question and answer troubleshooting forum to help solve technical problems arising from the use of plastics additives.     

Generalized differential quadrature analysis of MHD mixed convective motion of Casson fluids past an isothermal irregular slender geometry via Cattaneo–Christov's approach

Classical Fourier's theory is well-known in continuum physics and thermal sciences. However, the primary drawback of this law is that it contradicts the principle of causality. To explore the thermal relaxation time characteristic, Cattaneo–Christov's theory is adopted thermally. In this regard, the features of magnetohydrodynamic (MHD) mixed convective flows of Casson fluids over an impermeable irregular sheet are revealed numerically. In addition, the resulting system of partial differential equations is altered via practical transformations into nonlinear ordinary differential equations. An advanced numerical algorithm is developed in this respect to get higher approximations for temperature and velocity fields, as well as their corresponding wall gradients. For validating our numerical code, the current outcomes are compared with the available literature results. Moreover, it is revealed that the velocity field is more prominent in the suction flow situation as compared with the injection flow case. It is also found that the Casson fluid is hastened in the case of lower yield stress. Larger values of thermal relaxation parameters create a lessening trend in the temperature distribution and its related boundary layer breadth.     

Performance Analysis of Novel Multi-band Monopole Antenna for Various Broadband Wireless Applications

Wireless Personal Communications - This study investigates a novel concept of using slot and Coplanar Waveguide fed antenna to obtain multiband operation. The compact antenna includes a star...     

Correction to: Automatic COVID-19 detection mechanisms and approaches from medical images: a systematic review

Multimedia Tools and Applications -     

Low-temperature sintering of coarse alumina powder compact with sufficient mechanical strength

Coarse alumina powder compacts doped with various amounts of titania and copper oxide were pressurelessly sintered from 900 °C to 1600 °C. Their phase assemblages and microstructural evolution, as well as their properties, were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry/thermogravimetric (DSC/TG) analysis, and three-point bending and wetting test. The role of TiO₂ and CuO during the sintering is discussed in detail. The experimental results show that the liquid phase from the copper oxide appeared at approximately 1200 °C, so the solid-state reaction between alumina and titania took place at a lower temperature. Such solid state-reaction sintering had a strong impact on the grain growth and greatly promoted the densification of the alumina compact. In addition, the liquid phase inhibited the abnormal grain growth and microcracking. As a result, the coarse alumina powder compacts doped with 5 wt% TiO₂–CuO were fully densified and exhibited sufficient flexural strength (342±21 MPa) when sintered at a temperature of 1450 °C for 2 h.     

Systematic measurements of pulse height defects for heavy ions in surface-barrier detectors

The pulse height defect (PHD) in several Si-surface-barrier detectors for ¹²C, ¹⁶O, ²⁸Si, ⁶³Cu, ⁷⁹Br and ¹²⁷I ions was measured. The electric field strength dependence as well as the energy dependence were investigated. The results are compared with the recombination model. An empirical formula that describes well the total PHD is suggested.