Comparison of microwave and conventionally sintered manganese and niobium doped lanthanum germanate based apatites by micro Raman Spectroscopy

Sharma, Chetan; Singh, Kajal; Singh, Anirudh P.; Sharma, Payal; Mago, Sonia; Naithani, Vandana; Chadha, Rajiv

doi:10.1016/j.matchemphys.2019.122040

Cited by 3 publications

(2 citation statements)

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“…Regarding the electrically fast-fired samples, all data (with emphasis on the samples color) are indicative of a not fully fired body, even considering its lower total porosity. Based on the available data, and having in mind what others reported, concerning the effect on grain growth and greater crystallographic organization during microwave processing [ 21 , 25 , 28 , 29 ] (see Section 1.2 ), one can infer that faster microwave firing processes could potentiate the attainment of stoneware products with comparable features as those conventionally fired in less time and with lower pore sizes. More homogeneous microwave heating allows for faster firing processes, which potentiate faster crystallochemical transformations of the stoneware raw-materials [ 31 ], as well as the densification, not giving time for the pores to coalesce.…”

Section: Discussionmentioning

confidence: 88%

“…The authors stated that the desired phase transformation occurs at a lower sintering/firing temperature by MW heating, the microstructure of the sample exhibits more uniformly distributed grain sizes, and the relative density and crush load of ceramic pebbles are significantly enhanced. Sharma et al [ 28 ], investigated the effect of MW and conventional sintering on the doping behavior of Mn 2+ and Nb 5+ in lanthanum germanate based apatite. Microwave-fired apatites at 1400 °C for 30 min presented a higher density and more uniform grain growth than the samples conventionally fired at 1400 °C for 4 h. Moreover, MW-fired apatites showed higher Vickers hardness value, higher conductivity and lower activation energy values than the conventionally fired ones.…”

Section: Introductionmentioning

confidence: 99%

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A 3D-Printed Ceramics Innovative Firing Technique: A Numerical and Experimental Study

Santos,

Ramani,

Devesa

et al. 2023

Materials

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Additive manufacturing (AM), also known as three-dimensional (3D) printing, allows the fabrication of complex parts, which are impossible or very expensive to produce using traditional processes. That is the case for dinnerware and artworks (stoneware, porcelain and clay-based products). After the piece is formed, the greenware is fired at high temperatures so that these pieces gain its mechanical strength and aesthetics. The conventional (gas or resistive heating elements) firing usually requires long heating cycles, presently requiring around 10 h to reach temperatures as high as 1200 °C. Searching for faster processes, 3D-printed stoneware were fired using microwave (MW) radiation. The pieces were fired within 10% of the conventional processing time. The temperature were controlled using a pyrometer and monitored using Process Temperature Control Rings (PTCRs). An error of 1.25% was calculated between the PTCR (1207 ± 15 °C) and the pyrometer (1200 °C). Microwave-fast-fired pieces show similar mechanical strength to the references and to the electrically fast-fired pieces (41, 46 and 34 (N/mm2), respectively), presenting aesthetic features closer to the reference. Total porosities of ~4%, ~5% and ~9% were determined for microwave, electrically fast-fired and reference samples. Numerical studies have shown to be essential to better understand and improve the firing process using microwave radiation. In summary, microwave heating can be employed as an alternative to stoneware conventional firing methods, not compromising the quality and features of the processed pieces, and with gains in the heating time.

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