研究目的
Investigating the effect of preliminary heat treatment on the durability of reaction bonded silicon nitride crucibles for solar cells applications.
研究成果
The crucible heat treatment is a limiting factor to the number of its runs, as it must precede each solidification run and it contributes to the oxide accumulation in the entire crucible. At a certain threshold of the internal oxide content, crucibles crack due to the severe thermal stresses. The relatively high oxidation rates of the crucibles reduce the time to reach the threshold and hence the number of runs. Developing a passive oxide film on the outer surface of the crucible can hinder the oxygen penetration to the bulk, and hence the internal oxidation.
研究不足
The study is limited to the investigation of heat treatment's effect on the durability of silicon nitride crucibles under specific conditions. The applicability of findings to other materials or under different conditions is not explored.
1:Experimental Design and Method Selection:
The study involves heat treatment experiments on coated and uncoated silicon nitride crucibles at temperatures ranging from 900 to 1200 °C in air atmosphere.
2:Sample Selection and Data Sources:
Reaction bonded silicon nitride (RBSN) crucibles of two different porosities are investigated.
3:List of Experimental Equipment and Materials:
Thermogravimetry (TG) and Differential Thermal Analyzer (DTA) are used for measuring mass gain and oxidation rates. JEOL JXA-8500F Electron Probe Microanalyzer for oxygen compositional profiles, Bruker D8 A25 DaVinci X-ray Diffractometer for phase composition analysis, and LV-Fe-SEM (Zeiss Supra 55 VP) for secondary electron images, backscattered electron images, and EDS analysis.
4:Experimental Procedures and Operational Workflow:
Crucibles are subjected to oxidation cycles at different temperatures, with heating rate of 100 °C/hr. The oxidation degree is measured by oxygen compositional profile, oxide compounds content, and mass gain.
5:Data Analysis Methods:
Data refinement and quantitative analysis are performed using DIFFRAC.TOPAS 5.0.
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