Determination of Carbon and Sulfur in Silicon Carbide (CS744)

Significance of the Topic

Silicon carbide (SiC) is a critical material in sectors ranging from power electronics and LEDs to automotive braking systems. Precise measurement of carbon and sulfur content in SiC is essential for ensuring material purity, optimizing production parameters, and meeting stringent quality standards.

Objectives and Study Overview

This application note evaluates the performance of the LECO CS744 Series carbon and sulfur determinator for both carbon-only and simultaneous carbon/sulfur analyses in silicon carbide. The goal is to demonstrate method precision, detection limits, and practicality for routine quality control.

Methodology and Instrumentation

All analyses were performed on the LECO CS744 Series elemental analyzer. Sample preparation involved obtaining homogenous powder or granules of SiC and loading approximately 0.1 g samples into preheated ceramic crucibles (528-018HP) alongside specific accelerators. Two workflows were applied:

• Carbon-only determination using copper and iron chip accelerators
• Sulfur-only or simultaneous carbon/sulfur determination using iron powder, vanadium pentoxide, and LECOCEL accelerators

Key instrument parameters included a 10 s purge, 20 s delay, 10 s cool time, and 60 s integration for both elements. Calibration and drift correction were performed using certified reference materials (LCRM, LRM, NIST).

Main Results and Discussion

Carbon-only analyses of reagent-grade and 99% metals-basis SiC yielded mean carbon values of 29.38% (s = 0.06) and 29.77% (s = 0.05), closely matching the certified 29.95% standard. Simultaneous determinations produced carbon averages of 29.26% (s = 0.16) and 29.61% (s = 0.09), and sulfur at 0.0053% (s = 0.0002) for reagent grade and 0.0102% (s = 0.0007) for SiC sample. These results highlight excellent precision and low-level sulfur detection capability.

Benefits and Practical Applications

The described method offers:

• High-precision total carbon measurement to monitor free carbon and SiC ratio
• Low detection limits for sulfur, crucial for impurity assessment
• Automated sample loading options for high throughput
• Robust calibration protocols ensuring data reliability

These advantages support routine quality control in SiC manufacturing and research laboratories.

Future Trends and Potential Applications

Advancements may include integration with Industry 4.0 data platforms, expanded analysis of other nonmetallic impurities, miniaturized detectors for in-line process monitoring, and application of machine learning for predictive maintenance and real-time quality assurance.

Conclusion

The LECO CS744 Series analyzer delivers accurate, precise, and efficient determination of carbon and sulfur in silicon carbide. Its versatility for both single-element and simultaneous analyses makes it a valuable tool for ensuring material quality and optimizing production processes.

Instrumentation Used

• LECO CS744 Series carbon and sulfur determinator
• Ceramic crucibles (528-018HP)
• Copper and iron chip accelerators (502-492HP, 502-231HP)
• Iron powder and vanadium pentoxide accelerators (501-078, 501-636-HAZ)
• LECOCEL combustion aid (763-266)

References

• LECO Corporation. Determination of Carbon and Sulfur in Silicon Carbide. Application Note, Form No. 203-821-635, May 2021.
• LECO CS744 Operator’s Instruction Manual.
• Certified reference materials from LECO (LCRM, LRM) and NIST.