The optimal process conditions for sintering magnesium oxide after refilling are: holding at 800–1000℃ for 1–2 hours, using high-purity nitrogen protection, segmented temperature control, and natural cooling with the furnace. This process ensures sufficient recrystallization of magnesium oxide grains, forming a dense and stable insulating structure.
Detailed Explanation of Optimal Process Parameters
|
Stage |
Optimal Conditions |
Key Role |
|
Heating Rate |
≤ 5℃/min |
Prevents thermal shock leading to deformation or internal cracks in metal tubes |
|
Sintering Temperature |
800–1000℃ |
Activates recrystallization of magnesium oxide grains, improving density and insulation strength |
|
Holding Time |
1–2 hours |
Ensures complete grain growth and eliminates internal stress |
|
Atmosphere |
High-purity nitrogen (≥99.99%) or vacuum, oxygen content <100ppm |
Prevents high-temperature oxidation and carbonization, ensuring material purity |
|
Cooling Method |
Natural cooling with the furnace to <200℃ |
Avoids rapid cooling causing thermal stress cracks, maintaining structural integrity |
The entire process must be carried out in a dust-free (≤100,000 class), constant humidity (RH≤30%) cleanroom to prevent dust and moisture contamination.
Supporting Quality Assurance Measures
Equipment Requirements: Use a sintering furnace with a PID temperature control system and automatic recording function to ensure traceable temperature curves;
Material Standards: The filler powder must be electrical grade high-purity magnesium oxide (≥99.9%), with a particle size of 100–200 mesh;
Filling Density: Controlled at 2.8–3.2 g/cm³, achieving uniform compaction through high-frequency vibration + hydraulic pressing;
Sealing Process: The outlet end uses ceramic sealing adhesive or metal sealing to achieve an IP65 or higher protection rating.
