Zirconium Foil: Grades, Specifications and Quality Control Guide
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What Zirconium Foil Is and Where It Is Used
Zirconium foil is a thin, cold-rolled product made from commercially pure zirconium or a zirconium alloy. It combines a low thermal neutron absorption cross section with outstanding resistance to corrosive media, so it appears in two very different fields: nuclear service, where zirconium alloys are used for fuel cladding and structural components, and chemical processing, where zirconium linings, heat exchangers, reactor internals and vessel internals handle aggressive acids that attack stainless steel. Foil and thin strip are also used for getters, sputtering targets, medical implants and laboratory components.
Thickness is the defining feature of the product. Foil is rolled down to a fraction of a millimetre and must remain flat, bright and free from wrinkles, because a crease or a thin spot cannot be corrected after rolling.
Grades and Standard Designations
Two families are normally offered: commercially pure zirconium and zirconium alloys containing tin, iron, chromium or niobium for higher strength in reactor service.
| Grade | Material | Typical characteristics | Typical use |
|---|---|---|---|
| Zr1 | Commercially pure zirconium | Lower alloy content, good ductility | Chemical process components, liners |
| Zr2 | Commercially pure zirconium | Higher strength than Zr1, good corrosion resistance | Heat exchangers, reaction vessels |
| Zr702 | Zirconium alloy with tin and iron | Balanced strength and corrosion resistance | General industrial and chemical service |
| Zr704 | Zirconium alloy with tin, iron and chromium | Improved corrosion resistance in specific media | Nuclear and chemical equipment |
| Zr705 | Zirconium alloy with niobium | Highest strength of the range | Pressure service, structural parts |
Rods, bars, plate, sheet and strip in these grades are specified under ASTM B550, ASTM B551 and related wrought zirconium standards, while nuclear applications call for alloys produced to the appropriate nuclear-grade specification. Buyers should quote the grade together with the applicable standard so that composition and mechanical requirements are unambiguous.
Dimensional and Physical Specification
| Parameter | Range or value |
|---|---|
| Material | Pure zirconium or zirconium alloy |
| Grades | Zr1, Zr2, Zr702, Zr704, Zr705 |
| Thickness | 0.05 to 20 mm |
| Width | 20 to 300 mm |
| Length | 20 to 3000 mm |
| Purity | 99.95 percent and 99.995 percent minimum |
| Density | 6.52 g/cm3 |
| Melting point | 1852 plus or minus 2 degrees Celsius |
| Supply condition | Cold rolled, bright surface |
Custom thickness, width and length are rolled to order within these windows. Because zirconium has a density only slightly above that of steel and a melting point close to that of titanium, foil is produced on precision rolling mills with tight control of roll gap, tension and pass schedule.
Rolling, Annealing and Surface Quality
The mechanical quality of zirconium foil is decided during rolling and intermediate annealing rather than in final inspection. A controlled pass schedule with accurately set anneal temperature and soak time produces a uniform internal metallographic structure, a smooth surface free from wrinkles, and an even thickness profile across the width and along the length. Edge quality matters as much as the surface: properly rolled foil does not develop longitudinal or transverse tears, so it can be handled and stamped without scrap.
Annealing control - grain structure is kept uniform to give consistent tensile properties and predictable forming behaviour.
Flatness and finish - bright, cold-rolled surfaces support subsequent welding, brazing and cladding operations.
Anti-blocking performance - coil layers must separate cleanly when unwound, so surface topography and winding tension are controlled together.
Thickness tolerance - closely held across the coil so that downstream forming and shielding calculations remain valid.
Testing and Inspection
Every lot is verified before packing:
Chemical composition analysis to confirm grade and interstitial content.
Mechanical property testing, including tensile strength, yield strength and elongation.
Ultrasonic testing to detect internal defects and delamination.
Appearance and dimensional inspection covering thickness, width, length and flatness.
Additional flaw detection or eddy current testing when the end use calls for it.
Test results are reported per heat number so that material can be traced from the ingot through rolling to the finished coil.
Packaging, Handling and Storage
After coiling, each roll is wrapped in pearl cotton and packed into a wooden box. That combination prevents coil layers as well as packed rolls from striking one another in transit and keeps outside objects from denting the edges during loading, shipping and final delivery. Zirconium is not damaged by ordinary humidity, but the bright surface can pick up fingerprints and handling marks, so rolls should be stored indoors, kept dry and lifted with clean gloves and spreader bars rather than hooks. Material awaiting use should stay in its original packing until the moment of cutting or forming.
Frequently Asked Questions
Q: What is the difference between Zr702 and Zr705?
Both are wrought zirconium alloys, but Zr705 contains niobium and reaches noticeably higher strength, while Zr702 offers a well balanced combination of strength, ductility and corrosion resistance for general industrial service.
Q: What purity levels can be supplied?
Two grades are routinely produced, with minimum purity of 99.95 percent and 99.995 percent respectively; the higher level is chosen for applications sensitive to trace impurities.
Q: Can foil be supplied in custom sizes?
Yes. Thickness, width and length are rolled to order within the standard windows of 0.05 to 20 mm, 20 to 300 mm and 20 to 3000 mm.
Q: Why is flatness so important for zirconium foil?
A crease or wavy edge cannot be rolled out afterwards and causes misalignment during stamping, welding or cladding, so flatness is controlled during rolling and checked in final inspection.
Q: How is the coil protected during transport?
Each coil is wrapped in pearl cotton and placed in a wooden box, which isolates the layers and shields the edges from impact damage in transit.
Q: What testing is carried out before shipment?
Chemical composition, mechanical properties, ultrasonic testing and appearance and dimensional inspection are standard, with flaw detection or eddy current testing added when required.
