Humidity is the silent killer of sintering furnaces. When MoSi2 elements are exposed to moisture during low-temperature phases, they fall victim to a phenomenon known as "Pest Oxidation."

What is Pest Oxidation?

Between 400°C and 600°C, the protective $SiO_2$ layer is not yet dense enough to seal the element. If moisture is present, oxygen and water vapor penetrate the material, causing rapid, volumetric expansion. This literally causes the heating element to crumble into a fine grey powder from the inside out.

Walla’s Pre-Heat Strategy

If your furnace has been sitting idle in a humid lab, never jump straight into a 1,500°C cycle. Use this Moisture-Purge Protocol:

• Low-Temp Soak: Run a program from 50°C to 300°C, holding for 60 minutes.
• Ventilation Max: Keep your exhaust system at maximum suction during this phase to pull the evaporating water vapor out of the chamber before it can condense on the elements.
• Monitor the Humidity: If your lab’s relative humidity exceeds 65%, consider using a dehumidifier in the sintering room.