Determination of Carbon in Nitrides

Importance of the Topic

Accurate quantification of carbon in nitride materials is crucial for ensuring their desired mechanical, electrical and chemical properties. Trace levels of carbon impurities can influence performance and reliability in advanced ceramics, electronics and refractory applications. A robust analytical approach enables quality control, process optimization and compliance with material specifications.

Objectives and Overview of the Study

This application note describes a validated procedure for determining carbon content in various nitride samples using the LECO C744 combustion analyzer. The protocol covers sample preparation, instrument setup, blank correction, calibration and sample analysis. Certified reference materials (CRMs) are employed for method verification.

Methodology and Instrumentation

The analytical workflow comprises:

• Instrument: LECO C744 combustion analyzer
• Sample preparation: crush solid nitride samples to a uniform mesh; remove surface contamination
• Crucibles: preheated ceramic crucibles (528-018 or 528-018HP), baked at ≥1000 °C in a muffle or ≥1250 °C in a tube furnace, handled with clean tongs
• Accelerators: ~1 g copper (502-492) and ~1 g iron chip accelerator (502-231) per analysis
• Blank determination: minimum three replicates with copper and iron in empty crucibles
• Calibration/drift correction: use steel chip CRM (JK Nr 21) and nitride CRMs (JCRM R007, R008) with three replicates each; linear forced-through-origin calibration
• Analysis parameters: purge time 15 s, delay 20 s, cool time 10 s, furnace power 100 %, integration time 55 s, baselines 2 s
• Sample analysis: weigh 0.15–0.25 g nitride sample, add accelerators, analyze in triplicate

Main Results and Discussion

The method yields precise and accurate carbon measurements across multiple nitride matrices. Typical results:

• JCRM R007 (Si₃N₄) certified at 0.136 % C; measured average 0.132 % (s=0.001)
• JCRM R008 (Si₃N₄) certified at 0.097 % C; measured average 0.097 % (s=0.001)
• ZrN reagent grade; measured average 0.049 % C (s=0.001)
• AlN reagent and grade; measured average ~0.115 % C (s=0.001)
• BN reagent and grade; measured average ~0.064 % C (s=0.002–0.003)

These data demonstrate excellent repeatability and agreement with certification values. The steel chip calibration ensures linearity at low carbon levels.

Benefits and Practical Applications of the Method

This procedure offers:

• High sensitivity and precision for trace carbon in non-oxide ceramics
• Minimal sample mass and rapid throughput for routine analysis
• Robust blank correction and drift control for reliable data
• Applicability to QA/QC, research and industrial production environments

Future Trends and Potential Uses

Advances may include integration with automated sample handling, coupling with laser ablation sampling and expansion to other non-oxide matrices such as carbides and borides. Enhanced data processing and chemometric approaches could further lower detection limits and improve workflow efficiency.

Conclusion

The LECO C744 method provides a validated, reproducible approach for determining carbon in nitride materials. The use of preheated crucibles, accelerators and CRM-based calibration ensures accuracy and precision across a range of nitride compositions. This protocol supports rigorous quality assurance and material development needs.

Reference

LECO Corporation. Determination of Carbon in Nitrides, Application Note Form No. 203-821-513; 2017.