Blīva augsttemperatūras mullīta-ZrO2 keramika
Abstract
Parādīta piedevu (mālu minerāla – illīta, Si3N4, SiAlON), kā arī izejas pulveru izstrādes veida ietekme uz mullīta-ZrO2 keramikas saķepināšanas procesu (pielietojot tradicionālo saķepināšanas procesu un plazmas izlādes saķepināšanas procesu jeb SPS), fāžu sastāvu, struktūru, mehāniskajām un keramiskajām īpašībām.
Mālu piedeva sekmē pulvera daļiņu izmēru samazināšanos, veicina keramikas paraugu sablīvēšanos tradicionālā saķepināšanas procesā, bet dod pretēju efektu, pielietojot SPS procesu. Silīcija nitrīda un SiAlON nanopulveru piedevas ir efektīvas SPS procesā, sasniegta paraugu spiedes izturība ap 600 MPa Si3N4 piedevas gadījumā, termiskā trieciena izturību un elastības moduļa vērtības 180 – 220 GPa, kuras termiskā trieciena 1000/20 °C rezultātā samazinās pieļaujamās robežās. Šīs vērtības ir par aptuveni 20–25 % zemākas, pielietojot SiAlON piedevu.
Keramikas paraugu, kas saķepināti tradicionāli un pielietojot SPS procesu, mikrostruktūrā ir mullīta vai pseidomullīta kristāliski veidojumi ar ieslēgtiem ZrO2 graudiem, kas pārsvarā ir kubiskā modifikācijā. Galvenā atšķirība starp abos saķepināšanas procesos iegūtajiem paraugiem ir tā, ka tradicionāli saķepināto paraugu mikrostruktūrā ir novērojama ‘tukšumu’ veidošanās, kuri aizpildās ar mullīta kristāliem, it sevišķi palielinoties Si3N4 piedevai. Mikrostruktūra keramikas paraugiem, kas saķepināti ar SPS tehnoloģiju ir blīvāka – mullīta kristāli ir blīvi izvietojušies, un tiem nav mullītam raksturīgās prizmatiskās formas.
Dense high-temperature mullite-ZrO2 ceramics
The influence of some additives (clay mineral illite, Si3N4, SiAlON) and the processing of the initial powders on sintering of mullite-ZrO2 ceramics (using traditional or plasma dispersion sintering processes), composition, structure, mechanical and ceramic properties of phases is shown.
The clay additive contributes to the reduction of the particle size of the powder, facilitates the densification of the ceramic samples in the traditional sintering process, but vice versa if SPS is used. Silicon nitride and SiAlON nanopowder additives are effective in the SPS process; samples reach a compressive strength of approximately 600 MPa in the case of Si3N4 additive; thermal shock resistance and elastic modulus are in the range of 180–220 GPa, which under a thermal shock of 1000/20 °C will reduce within the permissible limits. These values are about 20–25 % lower if SiAlON additive is used.
The microstructure of the ceramic samples traditionally sintered or sintered using a SPS process is formed by crystalline mullite or pseudomulite crystals with enclosed ZrO2 grains that mostly are in the cubic modification. The main difference between the samples obtained in both sintering processes is that formation of voids filled with mullite crystals can be observed in the microstructure of traditionally sintered samples, especially if the amount of Si3N4 additive is increased. The microstructure of the ceramic samples sintered with SPS technology is denser – the mullite crystals are densely distributed and do not have the prismatic shape that is characteristic to mullite.
Keywords: |
mullīta-ZrO2 keramika; piedevas; saķepināšana; struktūra; īpašības
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References
U. Sedmalis, G. Sedmale, and I. Šperberga, “Alumīnija silikāti un to veidošanās iežos un tehnoloģiskos izstrādājumos,” Materiālzinātne un lietišķā ķīmija, vol. 22, pp. 83–87, 2010.
G. Sedmale, I. Sperberga, and U. Sedmalis, “Phase Composition and Properties of Mullite Ceramic in High-temperature Testing,” In Proc. of 9th International Conference “Modern Building Materials, Structures and Techniques”, 2007, pp. 32–34.
G. Sedmale, A. Hmelov, I. Sperberga, J. Grabis, and A. Pludons, “Hydrothermal synthesis of Al2O3-SiO2-ZrO2(Y2O3) powder and their application for high-temperature ceramics,” Chemine Technologija, vol. 50, no. 1, pp. 56–61, 2009.
Г. П. Седмале, A. B. Хмелёв, “Характеристика муллито-циркониевой керамики, полученной из порошков, синтезированных гидротермальным способом,” Стекло и керамика, vol. 4, pp. 23–27, 2011.
G. Sedmale, I. Sperberga, A. Hmelov, and I. Steins, “Characterisation of mullite – ZrO2ceramics prepared by various methods,” IOP Conference Series: Materials Science and Engineering, vol. 18, no. 22, p. 222014, Sep. 2011. https://doi.org/10.1088/1757-899x/18/22/222014
G. Sedmale, J. Grabis, and A. Hmelov, “Phase development and mechanical properties of high-temperature ceramic in the system mullite-ZrO2,” In Proc. of the International Conference “Functional and structural ceramic and ceramic matrix composites”, 2009, pp. 237–243.
Г. П. Седмале, A. B. Хмелёв, “Влияние дисперсности керамических порошков на свойства муллито-ZrO2 керамики,” Новые огнеупоры, no. 1, pp. 41–46, 2011.
G. Sedmale, I. Sperberga, J. Grabis, A. Hmelov, and L. Lindina, “Characterization of mullite-zirconia ceramics produced from different synthesized powders,” In Proc. of the 2nd International Congress on Ceramics – Global Roadmap for Ceramics, 2008, pp. 1–6.
G. M. Sedmale, I. Sperberga, A. Hmelov, U. Sedmalis, and A. Actins, “Phase Formation and Structure of Mullite-Alumina-Zirconia and Spinel-Ensta- tite Ceramics Developed from Synthetic and Mineral Raw Materials,” Materials Science Forum, vol. 575–578, pp. 953–958, 2008. https://doi. org/10.4028/www.scientific.net/msf.575-578.953
Г. П. Седмале, И. Э. Шперберга, А. Хмелов, А. Патмалниекс, “Образование керамики в системе Al2O3-SiO2-ZrO2 в присутствии минерализаторов,” Огнеупоры и техническая керамика, vol. 5, pp. 18–23, 2008.
G. M. Sedmale, I. Sperberga, I. Zalite, A. Krumina, and M. Rundans, “Mullite-ZrO2 Based Ceramics with Si3N4 Additive,” In Proc. of International Conference on Applied Mineralogy & Advanced Materials (AMAM 2015), 2015, pp. 51–52.
G. Sedmale, I. Sperberga, N. Zilinska, and I. Steins, “Spark Plasma Sintering (SPS) to the Mullite-Zirconia Ceramics Development,” Materials Science, vol. 21, no. 1, Mar. 2015. https://doi.org/10.5755/j01. ms.21.1.5501
G. Sedmale, I. Steins, I. Zalite, and G. Mezinskis, “Microstructure and properties of mullite-ZrO2 ceramics with silicon nitride additive prepared by spark plasma sintering,” Ceramics International, vol. 42, no. 3, pp. 3745–3750, Feb. 2016. https://doi.org/10.1016/j.ceramint.2015.10.112
G. Sedmale, M. Rundans, I. Sperberga, J. Setina, and A. Cimmers, “Ceramic of the Mullite–ZrO2–SiAlON System During Spark Plasma Sintering,” Refractories and Industrial Ceramics, vol. 57, no. 2, pp. 146–150, Jul. 2016. https://doi.org/10.1007/s11148-016-9944-3
Г. Седмале, М. Рунданс, И. Шперберга, Я. Сетиня, А. Циммерс, “Керамика системы муллит-ZrO2-SiAlON в процессе спекания в плазме искрового разряда (SPS),” Новые Огнеупоры, no. 3, pp. 134– 139, 2016.
DOI: 10.7250/msac-2018-0005
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