The key to preventing sintering failure after magnesium oxide refilling is to strictly control process parameters, ensure material purity and environmental cleanliness, and have the entire process performed by a compliant manufacturer. The following are specific preventative measures:
1. Strict Control of Sintering Process Parameters
Parameter Correct Practice Risk Avoidance
Temperature Range Precisely controlled at 800–1000℃, using calibrated thermocouples for real-time monitoring. Prevents incomplete recrystallization due to excessively low temperatures or deformation of the tube shell due to excessively high temperatures.
Holding Time Must be maintained for 1–2 hours to ensure sufficient grain growth. Avoids structural loosening and decreased insulation strength due to insufficient time.
Heating Rate ≤5℃/min, uniform heating. Reduces thermal shock and prevents cracks between the metal and magnesium oxide layers.
Cooling Method Natural cooling with the furnace to <200℃. Water cooling or air cooling is strictly prohibited. Prevents thermal stress cracks caused by rapid cooling, which can damage the seal.
It is recommended to choose professional equipment with a PID temperature control system to ensure a stable and traceable temperature curve.
2. Ensuring Material and Filler Quality
Use high-purity magnesium oxide powder (≥99.9%): conforming to HG/T 6445-2025 standard, Cl⁻ ≤0.05%, SO₄²⁻ ≤0.03%;
Preferred particle size: 100–200 mesh; ensures consistent thermal conductivity and insulation;
Filling density controlled at 2.8–3.2 g/cm³: achieving uniform compaction through an automated powder feeder and high-frequency vibration table;
Industrial-grade or recycled powder is prohibited: impurities can easily form conductive paths, leading to breakdown.
Consider requesting the manufacturer to provide a component analysis certificate and X-ray inspection report to verify the absence of off-cores and voids.
3. Ensure Atmosphere and Environmental Standards Meet Standards
Sintering Atmosphere: Must be conducted in a high-purity nitrogen or vacuum environment, with an oxygen content <100ppm;
Workshop Environment: Operation must be carried out in a cleanroom with a dust-free environment (≤100,000 class) and constant humidity (RH≤30%);
Sealing Process: Use high-temperature ceramic sealing adhesive or metal sealant to ensure an IP65 or higher protection rating.
Moisture and dust are the main causes of failure in the moisture test; contamination prevention must be implemented throughout the process.
4. Select Compliant Repair Service Providers
Prioritize units that participated in the drafting of the HG/T 6445-2025 standard, such as:
Liaoning Jiashun Technology
Dashiqiao Meier Magnesium Products
Shanghai Shiye Zhentai Chemical
These manufacturers have complete testing capabilities and can provide factory test reports and pressure/moisture test data, ensuring traceable repair quality.
