Engineering Ceramics: Microstructure-Property-Performance Relations and Applications: Advanced Processing and Properties of Engineering Ceramics
Sponsored by: ACerS Engineering Ceramics Division
Program Organizers: Young-Wook Kim, University of Seoul; Hua-Tay Lin, Guangdong University of Technology; Junichi Tatami, Yokohama National University; Michael Halbig, NASA Glenn Research Center
Monday 2:00 PM
October 10, 2022
Room: 415
Location: David L. Lawrence Convention Center
Session Chair: Young-Wook Kim, University of Seoul; Soshu Kirihara, Osaka University
2:00 PM Invited
Influence of Inversion Level of Ti:MgGa2O4 Ceramics on the Optical Absorption: Guangran Zhang1; Yiquan Wu1; Alexander Shemes2; Adrian Goldstein3; 1Alfred University; 2Ben-Gurion University of the Negev; 3Israel Ceramic and Silicate Institute
Ti-doped transparent MgGa2O4 ceramics, possessing a high inversion level, compare to MgAl2O4, were fabricated by Pulsed Electric Current Sintering at 950 °C under vacuum for 30–90 min. Optical transmission, emission, and electron paramagnetic resonance spectra were recorded. The maximal transmission level was ~70%, for a thickness of ~1 mm, which, while not very high, permitted the observation of the optical absorption bands location and profile. Comparison of the Ti doped MgGa2O4 (high inversion) and MgAl2O4 (low inversion) spinels, spectral characteristics revealed that a significant increase in the inversion level drives Ti3+ cations from octahedral toward tetrahedral sites. Interpretation of the fluorescence spectra suggests Ti4+ cations (mostly hexacoordinated) were accommodated by the host-despite the scarcity of oxygen in the atmosphere during the sintering process.
2:30 PM Invited
Transparent and Fluorescent Rare-earth-doped α-SiAlON Ceramics: Junichi Tatami1; Kohei Aminaka1; Motoyuki Iijima1; Takuma Takahashi2; Tsukaho Yahagi2; 1Yokohama National University; 2Kanagawa Institute of Industrial Science and Technology
α-SiAlON ceramics were prepared by doping various rare earths. As a result, transparent ceramics with high α-SiAlON fraction was able to be fabricated by adding Ho, Er, Tm, Yb, and Lu oxides. Smaller ionic radii of rare earth ions result in the easier nucleation of α-SiAlON due to the wide α-SiAlON formation region, and the suppression of grain growth due to higher viscosity of liquid phase existing in the ceramics. Consequently, the microstructure composed of finer α-SiAlON grains is attributed to the high transparency. The obtained transparent α-SiAlON ceramics also exhibit luminescence due to Ho3+, Er3+, Tm3+, Yb3+, and Yb2+. Furthermore, by co-doping Lu3+ and Ce3+, α-SiAlON ceramics with high transparency and blue luminescence due to the 4f-5d transition of Ce3+ were also obtained.
3:00 PM
Novel Gel-casting Route for Radially Graded All-ceramic Structures for Microwave Metamaterial Antenna Applications: Abhijeet Sarangi1; Dmitry Isakov1; Claire Dancer1; 1University of Warwick
Ceramics are required for metamaterial-based high efficiency microwave frequency antennas due to their high dielectric permittivity and breakdown strength, low thermal expansion and conductivity, and tolerance of harsh environments. However, the difficulties in producing graded structures entirely of ceramics mean that most transformation optics-based metamaterial dielectric structures comprise polymer matrices with varied loadings of high permittivity ceramic. Using polymers limits the working temperature and environment, as well as reducing the dielectric properties. We have developed a novel gel casting route for all-ceramic graded structures. Using ceramic materials with a range of dielectric performance and careful control of porosity, we demonstrate how permittivity variations can be controlled through microstructural variations alone. Key parameters of the gel casting route are described, as well as microstructural and spatially resolved permittivity measurement at microwave frequencies. This manufacturing route for functionally graded materials represents a significant development towards new metamaterial devices with customised electromagnetic properties.
3:20 PM
Effect of Initial α-phase Content on Mechanical, Thermal, and Electrical Properties of Pressureless Sintered SiC Ceramics: Young-Wook Kim1; Shynar Kultayeva1; Rohit Malik1; 1University of Seoul
By using α- and β-SiC starting powders, the effects of initial α-phase content on the properties of pressureless sintered SiC ceramics were investigated. For β-SiC starting powders, a coarse-grained microstructure with elongated platelet grains was formed by the β to α transformation of SiC in both solid state sintered (SSS) and liquid-phase sintered (LPS) SiC ceramics. In contrast, materials prepared from α-SiC powders exhibited a fine-grained microstructure with platelet grains in SSS-SiC and a fine-grained microstructure with equiaxed grains in LPS-SiC ceramics. This study revealed the beneficial effect of α-SiC starting powders in achieving low electrical resistivity and high thermal conductivity in SiC ceramics, which was attributable to their higher sinterability, lower impurity content, and lower phase transformation rate compared to β-SiC powders. The flexural strength increased by approximately 16% and 49% in SSS-SiC and LPS-SiC, respectively, with increasing initial α-phase content due to a decreased grain size.
3:40 PM Break
4:00 PM
Mechanical Properties and Fragmentation Mechanisms of Si/SiC Core-shell Nanoparticles: Kevin Kayang1; Alexey Volkov1; 1The University of Alabama
The porous material composed of nanoparticles (NPs) covered by ceramic coatings can be used in various applications as the materials for energy absorption, damping, and generation, as well as optical and light-weight multifunctional aerospace materials. The goal of the present work is to reveal the fundamental mechanisms of load transfer and fragmentation in hybrid NPs considered as building blocks of porous nanocomposites. For this purpose, the molecular dynamics compression and tension simulations of NPs composed of Si cores and SiC shells are performed. The shells represent coatings of individual nanoparticles, which can partially overlap and increase the mechanical integrity and durability of the material composed of such hybrid NPs. The effects of shell thickness, degree of shell overlap, NP size, temperature, shell polytype on the key mechanical properties of the NPs, such as elastic modulus, fracture stress, and toughness, are determined and compared with computational results obtained for single-material NPs.
4:20 PM
The Role of Micro-Scale Analysis Tools in Industrial Problem Solving: Jeanette Vass1; 1Auto and Materials
Detecting, testing, preventing, and controlling manufacturing and production failures is key to ensuring the reliability of commercial and consumer products. Characterization and identification of micron and submicron size particles is essential for understanding and managing certain manufacturing processes. Focusing on achieving manufacturer goals, such as producing quality products with consistent, reliable performance at a competitive price, requires careful planning and proper methodology. Microscale-Analysis tools are selected to aid manufacturers goals.The objective of this presentation is to demonstrate the value of SEM/EDS, FT-IR, Raman, and other non-destructive, micro-spectroscopic tools. My presentation will classify, compare, and contrast the advantages and limitations of common micro-scale analytical instruments, thereby providing the audience with a convenient Instrument-selection guide. Through specific case studies, I will establish the practical applications of Micro-Scale-Analysis-Tools for problem solving. I will conclude by discussing the need for accurate data acquisition and results interpretation to ensure meaningful results.
4:40 PM
Modular Piezoceramic/Polymer Composites with Locally Adjustable Piezoelectric Properties: Patrizia Hoffmann1; David Köllner1; Tobias Fey1; 1Friedrich-Alexander-Universität Erlangen-Nürnberg Institute Glass and Ceramics
Piezoceramic polymer composites combine piezoelectric sensitivity of the brittle ceramic with the high dielectric strength of the flexible polymer to gain novel properties. Typical composites for piezoelectric applications possess exclusively the same piezoelectric properties in the entire material. Therefore, we designed modular periodic composites of ceramic building blocks and polymer-matrix with individual piezoelectric properties for each block. The modular arrangement offers variable polarization directions and a new opportunity for local control of piezoelectric properties. Barium titanate building blocks were prepared by injection molding and assembled to 2-2 layer composites and honeycomb structures, which were bonded with ceramic-filled epoxy resin. The piezoelectric response was determined using direct excitation via Berlincourt method and indirectly by P-E-loop measurements. The influence of the different polarization directions of individual building blocks as well as the matrix thickness and filler content was investigated.