What performance is affected by insufficient magnesium oxide purity?

Heating elements are extremely vulnerable to failure in high-temperature and high-humidity conditions due to inadequate magnesium oxide purity, which negatively impacts insulation performance, thermal stability, moisture resistance, and long-term dependability.

1. Reduced Performance of Insulation

Root Cause: Conductive or hygroscopic impurities, as Cl⁻, SO₄²⁻, and Fe₂O₃, provide leakage pathways;

Low cold-state insulating resistance (<500 MΩ); abrupt resistance drop during hot operation, even near zero; elevated risk of malfunction and short circuit, endangering personnel and equipment safety.

As "invisible killers," sulphates and chlorides can cause electrochemical corrosion even in tiny concentrations.

2. Thermal Stability Deterioration

Root Cause: Impurities prevent recrystallization by lowering magnesium oxide's melting temperature and lattice stability.

Signs: Micropores increase at high temperatures, causing unequal heat conduction and the production of localised hot spots, which can lead to carbonisation, bulging, and even pipe rupture; Grain expansion is impeded during sintering, resulting in a loose structure.

Experience demonstrates that the hot-state insulation pass rate drops by almost 30% when Fe2O3 > 0.05%.

3. Considerably Diminished Resistance to Moisture

Root Cause: Moisture is readily absorbed by impurities like CaO and Cl⁻, which vaporises and builds up at high temperatures;

Signs: Insulation resistance drastically decreases from ≥500 MΩ to <200 MΩ following a wet test; Moisture ingress during operation causes pipe bursting incidents; condensation and corrosion at the sealing points speed up seal failure.

The material's rate of moisture absorption more than doubles when the CaO level is greater than 0.2%, significantly raising the risk.

4. Considerably Diminished Long-Term Dependability

Root Cause: Impurities cause structural deterioration and ongoing electrochemical corrosion;

Symptoms include: a high rate of reworkable parts encountering repeated failures, producing a "cannot be repaired, cannot be used for long" conundrum; even if initial testing is successful, the probability of early failure within three months approaches 70%; elevated secondary hazards, like cascading damage and system outages.

The primary need for guaranteeing longevity is high purity (≥99.9%); the average lifespan is reduced by 15% for every 0.1% drop in purity.