Engineering Sciences and Technology

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Near-net Shaping of Simple and Complex Ceramic Parts by 3D Printing and Investigations on the Physico-Chemical, Thermal, Mechanical and Microstructural Properties

(University of Hyderabad, 2021-09) Mamatha, S ; Das, Dibakar

3D printing of ceramics is an emerging area due to the flexibility and advantages for complex prototyping of the components/parts with the micro-features for versatile applications as revealed by recent increasing trends not only in publications but also in patents. In the current study, four advanced ceramic formulations such as alumina, magnesium aluminate spinel, cordierite and kaolinite clay has been established starting from the powder characterization through printing of various configurations. An indigenously supplied 3D printer was modified to suite a ram type/screw type extruders designed and fabricated in the current study. A naturally occurring environmentally friendly cellulose derivative (Methylcellulose) and its thermal gelation property in the temperature range of 35-42oC was used for the first time in 3D printing process. A pseudo-plastic paste was prepared with proper additives for each ceramic formulation and printing parameters such as printing speed, length to Diameter (L/D) ratio and self-standing distance are found to be critical to minimize the defects. The various configurations such as honeycombs, corrugated monoliths, discs, cylinders etc., were sintered to achieve the acceptable theoretical densities for various applications targeted. Collaborative research was also carried out at Baylor College of Medicine, USA and 3D printed fine spinel mesh for the possible applications in cranioplasty. The printed specimens were characterized for their physico-chemical, thermal, mechanical and microstructural properties using advanced ceramic characterization techniques and correlated with the processing parameters. Additionally, highly porous ceramic honeycomb structures were also prepared for the first time using the 3D printed poly lactic acid based (PLA) template replication process. Hot isostatic pressing (HIPing) of encapsulated green alumina compact is demonstrated for minimization of defects originating from layer by layer deposition while printing. The current study have also explored for the applications of various 3D printed ceramic formulations as high surface area substrates for wetland phytorid sewage treatment system and also corrugated monolith substrates for de-fluoridisation of potable water and have shown encouraging results.

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Synthesis, characterization and properties of Ti-Zr-Cu-Ni based metallic glasses and their use as filler materials for brazing joints

(University of Hyderabad, 2018-12-30) Rama Rao, P. ; Koteswararao, V. Rajulapati