Zone-Refined Tungsten is an ultra-high purity tungsten material produced by applying the zone-refining (zone-melting) technique to already high-purity tungsten. This process raises tungsten purity to >99.995% (5N+), making it one of the cleanest metallic tungsten materials available.
A narrow molten zone is passed slowly along a tungsten rod under ultra-high vacuum or inert gas. Impurities migrate with the molten zone and are removed, leaving behind an exceptionally pure and structurally uniform tungsten crystal.
Strengthening & Metallurgical Behavior
Crystal Perfection:
✔ Reduced dislocation density
✔ Minimal grain boundary contamination
✔ Fewer lattice defects
✔ Directional or near-single-crystal growth possible
Strengthening Mechanism:
Intrinsic lattice strength driven purely by purity and crystal quality.
No alloying, no dopants, and no second-phase strengthening.
Refining & Processing Properties
Start with >99.97% tungsten rod
Localized induction or electron-beam heating
Slow molten-zone translation (mm/hr)
Impurities migrate to tail end
Impurity-rich section removed
Processing Challenges:
Extremely slow and costly
Limited cross-section sizes
Requires ultra-clean vacuum or inert atmosphere
Available Forms
Zone-refined rods (most common)
Single-crystal or near-single-crystal bars
Precision discs and cylinders
Ultra-clean sputtering targets
Research-grade specimens
Sheets and foils are rare due to recrystallization sensitivity.
Key Characteristics
✔ Ultra-high purity (5N+)
✔ Lowest impurity-driven embrittlement
✔ Exceptional thermal & electrical stability
✔ Superior UHV compatibility
✔ Reduced grain-boundary failure
✔ Extremely low contamination risk
Limitations
Very high cost
Limited size availability
Not suitable for mass-production applications
Typical Applications
Semiconductor & Electronics: Ultra-pure sputtering targets, gate electrodes, diffusion research
Ultra-High Vacuum: Ion sources, vacuum electrodes, accelerator components
Scientific & Metrology: Reference materials, high-temperature physics research
Fusion & Plasma: Diagnostic probes, plasma-interaction studies
Advantages of Zone-Refined Tungsten
✔ Highest purity tungsten commercially available
✔ Superior high-temperature reliability
✔ Lowest outgassing rate
✔ Improved radiation damage resistance
✔ Exceptional microstructural uniformity
Why Choose Zone-Refined Tungsten?
Choose Zone-Refined Tungsten when contamination tolerance is near zero, UHV or semiconductor environments are involved, and pristine high-temperature performance with repeatable material behavior is required for research-grade or mission-critical applications.