What are the specific steps of professional refilling and sintering?

The specific steps of professional refilling and sintering include disassembly and cleaning, vacuum drying, high-purity magnesium oxide filling, vibration compaction, high-temperature sintering, and sealing testing. The entire process is completed in a dust-free and humidity-controlled workshop to ensure that the insulation performance is restored to the factory standard.

1. Disassembly and Deep Cleaning: Completely disassemble the failed heating element and remove the old magnesium oxide powder; Use ultrasonic cleaning equipment to remove residual carbides, scale, and metal debris from the cavity; Use compressed air to purge to ensure no particles remain inside.

2. Vacuum Drying of the Cavity: Place the cleaned metal tube in a vacuum drying oven at 120–150℃ and bake for 2–4 hours; Control the vacuum degree to ≤10Pa to thoroughly remove moisture adsorbed on the tube wall; Prevent insulation performance degradation due to moisture during subsequent filling.

3. High-purity magnesium oxide powder filling: Using an automated powder feeder, electrical-grade magnesium oxide powder with a purity ≥99.9% is uniformly injected into the tube;

The filling density is strictly controlled at 2.8–3.2 g/cm³ to avoid voids or off-center filling; Powder with a particle size of 100–200 mesh is preferred to improve thermal conductivity and insulation consistency.

4. Vibration compaction and hydraulic pressing: A high-frequency vibration table is used to tightly arrange the magnesium oxide particles, eliminating micropores;

Axial compaction is performed using a hydraulic device to ensure the stability of the filling structure;

This process prevents localized overheating or breakdown due to loosening during operation.

5. High-temperature sintering and shaping: Sintering is performed at 800–1000℃ in an inert atmosphere (such as nitrogen) for 1–2 hours;

This promotes the recrystallization of magnesium oxide grains, forming a dense and stable insulating structure;

This significantly improves withstand voltage performance and anti-aging ability.

6. Sealing and Terminal Treatment

Use high-temperature ceramic sealing adhesive or metal sealing structures to seal the outgoing terminals;

Ensure a sealing rating of IP65 or higher to prevent moisture infiltration along the leads;

Install high-quality terminals and perform anti-oxidation treatment.

7. Mandatory Performance Testing