PlasmaPure-UC alumina is said to be 99.9% Al2O3. It has one-sixth the sodium, half the iron, and about one-twentieth the silicon of 99.5%-pure alumina.
The material etches less than 0.2 nm/min in 15% KOH or 10% HF with 30% HNO3. Its dielectric loss tangent is less than 0.00002. The fine-grained material is also said to have four times better corrosion resistance than 99.5%-pure alumina.
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