553 99.9% Si vs 441 99.5% Si silicon metal powder
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Silicon Metal Powder Grades 553 vs 441: Composition and Application Guide
1. Grade Designations
Silicon metal powder grades 553 and 441 are designated by the impurity limits of iron, aluminum and calcium: grade 553 = Fe ≤ 0.5%, Al ≤ 0.5%, Ca ≤ 0.3%; grade 441 = Fe ≤ 0.4%, Al ≤ 0.4%, Ca ≤ 0.1%. The silicon content of both grades is typically in the 98.5–99.5% range. (Purity figures such as "99.9%" quoted in some materials do not correspond to the grade designation and should be verified against the actual analysis.)
2. Applications by Grade
| Feature | 553 | 441 |
|---|---|---|
| Fe/Al/Ca limits | 0.5 / 0.5 / 0.3% | 0.4 / 0.4 / 0.1% |
| Typical use | Steelmaking, aluminum alloys, foundry inoculants | Chemical-grade applications, silicone production, higher-purity alloys |
| Particle size | Coarser (-40/-80 mesh) for metallurgy | Finer (-100/-200 mesh) for chemical reactivity |
3. Selection Guidance
Use coarser powders for metallurgical operations (steelmaking deoxidation, aluminum alloys) where reactivity control matters less.
Use fine, uniform powders for chemical processes (silicone, silanes) where consistent reactivity is required.
Verify the actual Si content, Fe/Al/Ca limits and particle size distribution against the applicable standard (e.g. GB/T 2881) and the mill certificate.
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