Determination of Carbon in Silicon Carbide

Significance of the topic

Silicon carbide (SiC) is a material prized for its hardness and thermal stability, finding applications from electronics to automotive components. Accurate determination of total carbon content in SiC is critical for quality control, ensuring material purity and proper ratio of silicon carbide to free carbon produced by carbothermic reduction.

Objectives and Study Overview

This application note describes a robust procedure for quantifying total carbon in SiC samples using the LECO 844 Series combustion analyzer. The goal is to demonstrate method accuracy, precision, and suitability for routine quality control in industrial environments.

Methodology

The procedure involves precise weighing of SiC powder (~0.075 g) and combustion under a purified oxygen flow. Inductive heating converts carbon in the sample to CO2 and CO; a heated catalyst ensures complete oxidation to CO2. Non-dispersive infrared detectors quantify the evolved CO2, with blank corrections and calibration performed using certified reference materials.

Instrumentation

The method utilizes the LECO 844 Series (C844, CS844, CS844ES) combustion analyzer equipped with:

• Induction furnace
• Heated dust filter and drying column
• High-temperature catalyst
• Non-dispersive infrared (NDIR) detectors
• 528-018/528-018HP ceramic crucibles, copper and iron accelerators

Main Results and Discussion

Calibration was performed using NMIJ 8002-a SiC (29.93% C) via a linear, zero-origin model. Analysis of standard and reagent-grade SiC yielded average carbon contents of 29.70% (s = 0.08) and 28.79% (s = 0.08), respectively. These results demonstrate method repeatability below 0.1% RSD and accuracy within ±0.15% of certified values.

Benefits and Practical Applications

The outlined approach provides:

• Rapid sample throughput with minimal preparation
• High precision and accuracy suitable for QC labs
• Compatibility with a wide range of SiC sample types

This method supports material manufacturers in ensuring product consistency and performance.

Future Trends and Potential Applications

Advancements may include automation of sample handling, integration with laboratory information management systems (LIMS), and multi-element simultaneous determination. Miniaturized sensors and enhanced detector technologies could further streamline carbon analysis in SiC and related materials.

Conclusion

The LECO 844 Series combustion analysis delivers accurate and reproducible total carbon measurements in silicon carbide, fulfilling stringent quality control requirements across diverse industrial sectors.

Reference

LECO Corporation. Determination of Carbon in Silicon Carbide. Application Note, Form No. 203-821-649, Rev.0, 2022.