会社のニュース How Furnace Atmosphere Affects SiC Performance in High-Temperature Applications？

In high-temperature processes such as lithium battery material production and ceramic sintering, silicon carbide (SiC) components are widely used for their strength and thermal stability.

However, field experience shows that the same SiC material can perform very differently under different furnace atmospheres.

The key variable is not just temperature—it is the atmosphere composition.

This article explains how different gas components affect SiC performance and why atmosphere control is critical.

At high temperature, SiC reacts with oxygen:

SiC + O₂ → SiO₂

• Forms a thin SiO₂ layer
• Acts as an initial protective barrier

In complex atmospheres (especially with lithium), this layer becomes unstable and can be destroyed.

• Hygroscopic raw materials
• Incomplete drying
• Ambient humidity

• Accelerates oxidation reactions
• Enhances transport of reactive species
• Promotes corrosion kinetics

Even small amounts of H₂O can significantly increase degradation rate

• Li vapor
• LiOH
• Li₂CO₃ decomposition products

These react with SiO₂:

SiO₂ + Li₂O → Li₂SiO₃

At 700–800°C:

• Lithium silicates soften or melt
• Form a molten phase

• Dissolution of protective SiO₂ layer
• Penetration into SiC structure
• Rapid material degradation

This is the dominant corrosion mechanism in NCM production

• Organic binders
• Carbon reactions
• Decomposition processes

• Carbon deposition (coking)
• Reduction reactions
• Surface contamination

Effects depend strongly on local process conditions

Used as protective atmospheres

• Do not directly react with SiC
• Help control oxidation

Impurities (O₂, H₂O, Li species) can still exist

“Inert atmosphere" ≠ “safe environment"

In real production environments, these gases do not exist independently.

Instead, they interact:

• O₂ → forms SiO₂
• Li species → destroy SiO₂
• H₂O → accelerates both

Result:

A dynamic cycle of oxidation → reaction → destruction

Different atmospheres lead to completely different outcomes:

• Rapid loss of protective layer
• Internal structural degradation
• Shortened service life

• Improve sealing
• Reduce air leakage

• Pre-dry raw materials
• Control humidity

• Optimize process conditions
• Reduce lithium vapor concentration

• Not just gas type—but purity

SiC performance is not only determined by material properties

It is strongly influenced by furnace atmosphere composition

Atmosphere → Reaction → Structure → Performance

Understanding and controlling furnace atmosphere is essential for:

• Extending SiC component life
• Reducing maintenance
• Improving production stability

In many cases, atmosphere control is as important as material selection.