Chrome Oxide for Sputtering Targets and Varistors: Purity at the ppm Scale

Two very different components — a plasma-deposited coating and a ceramic surge protector — share one raw material and one obsession: chemical शुद्धता measured in parts per million.

Cr₂O₃ Sputtering Targets

Chromium oxide coatings are the industrial standard for wear resistance: anilox rolls, pump seals, wire guides, textile machinery. The coatings are typically reactively sputtered or deposited from sintered Cr₂O₃ targets, and film quality is a direct photograph of powder quality.

EG-99H at ≤50 ppm Na₂O, ≤100 ppm Fe and ≤5 ppm magnetic impurities is the feed stock that lets a target house guarantee its own product.

ZnO Varistors: Chemistry at the Grain Boundary

A ZnO वेरिस्टर is a polycrystalline ceramic whose non-linear I-V curve lives almost entirely in a few nanometers of grain-boundary chemistry. The classic formulation — ZnO plus Bi₂O₃, Sb₂O₃, MnO, CoO and Cr₂O₃ — builds a double Schottky barrier at every grain boundary. Chromium stabilizes the boundary phase and suppresses the electrical aging that shifts clamping voltage over the surge lifetime.

Too much sodium or iron in that boundary chemistry, and the non-linearity coefficient α degrades; the device becomes a mediocre resistor. The डोपिंग window is small — which is exactly why वेरिस्टर makers buy इलेक्ट्रॉनिक ग्रेड Cr₂O₃ and not pigment.

Two Grades, Two Jobs

• EG-99 — the volume electronic grade for वेरिस्टर डोपिंग and thick-film work: ≥99.2 %, Na₂O ≤100 ppm.
• EG-99H — the clean-room grade for targets and premium परावैद्युतs: ≥99.5 %, Na₂O ≤50 ppm, iron and magnetics tightened to target-house levels.