Trace Impurity Review Table
Semiconductor programs should define restricted elements before sample production. The table helps procurement and process teams turn purity expectations into a measurable qualification file.
| Element | Typical Limit | Why Controlled |
|---|---|---|
| Oxidation loss | Anti-oxidation route selected by temperature and exposure time | Oxidation near the liquid line is a leading cause of shaft thinning and breakage. |
| Thermal shock cracking | Preheat and operating procedure reviewed with graphite grade | Fast immersion and thermal cycling can crack rotors even when material quality is acceptable. |
| Thread damage | Visual and dimensional thread acceptance required | Damaged or mismatched threads increase wobble, assembly failure, and head loss risk. |
| Surface erosion / metal wetting | Reviewed by alloy, flux, chlorine-free process needs, and treatment route | Molten-metal chemistry and flux exposure drive rotor erosion and surface degradation. |









