New method of free silicon determination in pressureless sintered silicon nitride by Raman spectroscopy and XRD
Autor: | A.A. Parkhomenko, A.P. Kuzmenko, V. V. Krasil’nikov, O.A. Lukianova, A.N. Khmara |
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Rok vydání: | 2019 |
Předmět: |
Materials science
Silicon Sintering chemistry.chemical_element 02 engineering and technology Hot pressing 01 natural sciences chemistry.chemical_compound symbols.namesake 0103 physical sciences Materials Chemistry Ceramic Composite material 010302 applied physics Process Chemistry and Technology 021001 nanoscience & nanotechnology Microstructure Surfaces Coatings and Films Electronic Optical and Magnetic Materials Silicon nitride chemistry visual_art Ceramics and Composites symbols visual_art.visual_art_medium Grain boundary 0210 nano-technology Raman spectroscopy |
Zdroj: | Ceramics International. 45:14338-14346 |
ISSN: | 0272-8842 |
Popis: | Formation of silicon affects different physical properties of silicon nitride ceramics. Decomposition of Si3N4 and formation of free Si are highly important processes and depend on many factors. The proposed method of combined nano-Raman spectroscopy and X-ray diffraction (XRD) allows quantitative analysis of Si in silicon nitride. Raman spectroscopy enables the determination of atomic bonds and rapid and easy identification of free silicon. Further analysis of the crystalline phases by XRD enables the calculation of the amount of free silicon. The proposed complex method allows the characterization of such complicated processes as silicon nitride decomposition, microstructure formation and, in particular, the formation of the nanoscale grain boundary phase because Si nanosized precipitates are the nucleants of secondary phases during crystallization. Strong 522.8 cm−1 mode and 943.1–984.3 cm−1 transverse optical modes of free Si were clearly observed in the investigated silicon nitride that was subjected to pressureless sintering at 1800 °C. Reported ceramics demonstrated typical microstructures with elongated grains and relatively high microhardness and Young's modulus. It was shown that the aspect ratio depended linearly on the microhardness and Young's modulus. High values of the Young's modulus (more than 290 GPa) and microhardness (more than 1800 HV) were shown for reported silicon nitride produced by hot pressing and pressureless sintering via cold isostatic pressing with a higher quantity of sintering agent. The features of molecular structure of the reported Si3N4 ceramics were clearly described and discussed in detail and were found to be in good agreement with the microstructure and phase composition of these ceramics. |
Databáze: | OpenAIRE |
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