How to determine if reworked magnesium oxide meets standards?

Triple verification of the chemical composition, physical structure, and electrical properties is necessary to ascertain whether reworked magnesium oxide satisfies criteria. The fundamental strategy is to use the HG/T 3928-2012 standard as the foundation, along with on-site testing and third-party CNAS testing for a thorough evaluation.

 

1. Testing for Chemical Composition (Authoritative Judgement Basis) For chemical analysis, samples must be forwarded to a facility with CNAS certification. The following are the qualifying criteria and test items:

Standard Testing Procedure for Testing Item Qualification

Acid-Base Titration: MgO Content ≥ 95%

Method of Active Magnesium Oxide > 60% Hydration

Method of Filtration and Weighing Hydrochloric Acid Insoluble Matter < 0.5%

Method of Cl⁻ < 0.02% Silver Nitrate Titration

Barium Sulphate Turbidity Method: SO₄²⁻ < 0.1%

Ignition Loss < 5% 950℃ Constant Weight Approach

Recommended Organisations: Zhongxi Testing, Wuhan Kehai Inspection Co., Ltd. Reports must be legally valid and contain the CMA/CNAS mark.

 

2. Structural and Physical Verification (Vital to Process Control)

Verification Method for Item Acceptance Criteria

After vibration and compression, the actual filling density was 2.8–3.2 g/cm³.

Grain Recrystallization Metallographic Analysis (Gold Standard) Grain development, distinct boundaries, and dense structure

Integrity of Internal Structure X-ray inspection revealed no voids, off-center cores, or uneven density (resolution ≥5μm).

The primary technique for ascertaining whether sintering is actually accomplished is metallographic analysis, which directly reflects the internal state of the material.

 

3. Performance Testing for Electrical and Sealing (Operational Reliability Assurance)

Test Subject

Acceptance Criteria

Test Situation

Resistance to Cold Insulation

500 MΩ or more

500V DC, 30% relative humidity

Resistance to Hot Insulation

200 MΩ or more

measured after 30 minutes of operation within two seconds of a power outage.

Performance of Withstand Voltage

AC 2000V, no malfunction after a minute

Typical surroundings

Tightness of Air

After 30 minutes of 0.3MPa pressure testing, there was no leakage.

Test of underwater pressure

Hot testing is essential since it can find hidden flaws like "passing cold but failing hot."

All-inclusive Judgement Procedure

X-ray and density screening should be done first to rule out structural abnormalities.

Next, validate grain recrystallization using metallographic analysis;

Lastly, send for full electrical testing and chemical composition testing to create a closed-loop verification.

It is advised to create a unique coded file, obtain complete lifecycle traceability, and sample at least three pieces from each batch.