Niobium cannot be annealed using traditional jewelry-making methods; annealing must be done in a vacuum chamber with inert gas and is typically done in an industrial setting. Although the metal is very tough, once annealed, it stays soft and is very slow to work-harden.
Because of the naturally occurring oxide layer, niobium cannot be soldered, but can be welded using fusion welders, such as the Sparkie® II, or mini arc welders such as the Orion 100c. Laser-welding is also effective. Niobium is also a terrific candidate for cold connections such as rivets and jeweler’s nuts & bolts or screws. Most adhesives, including cyanoacrylates (super glues), cannot bond with the oxide layer always present on the metal surface; Reactive Metals Studio has had good results using E6000.
Very ductile, niobium is extremely easy to form and manipulate--even wood tools effectively move the metal. In rolling, drawing and forging, the metal can be reduced up to 90%. In deep-drawing, where the draw is less deep than the metal diameter, niobium conforms beautifully; for multiple draws, pull at least 40% of the desired depth on the first draw. Use a tallow or drawing wax to lubricate. Note: Drawing is not recommended; in drawing, it is not advisable to use standard draw plates with the usual lubricants; a special (very costly) commercial lubricant would be required.
Drilling and Cutting
Niobium can be done with high-speed twist drills, checking often to watch for excessive wear. Use a good lubricant, such as a vegetable or water-soluble oil, water alone is not sufficient.
Blanking and Punching
Use steel dies or punches with a lubricant. Allow a clearance of at least 6% of the metal thickness.
The typical machining processes (surface speed approx. 80 ft./min.) are effective on niobium, which performs much like copper. Lubrication is a must, as the metal tends to gall easily. Avoid allowing shavings and chips to build up; this build-up can cause excess heat and pressure to accumulate and result in tool damage.
Grinding niobium, though not easy, can be accomplished using silicon carbide wheels or rubber-impregnated wheels; again, always use a cooling lubricant.
Polishing and Finishing
Hand-finishing is no different for niobium than for most other metals. Use polishing compounds like Zam and White Rouge and keep a separate polishing wheel dedicated only to your niobium work (other metals can contaminate the surface of the metal and prevent anodizing later). Use soft buffs and gentle pressure. Matte and textured surfaces offer a variety of interesting effects in finished pieces--particularly before anodizing.
Using standard vibratory machines, mass finishing of niobium pieces can be accomplished if the media and equipment are kept extremely clean and the media used is dedicated only to niobium work. Note: Media is a must; do not burnish niobium on itself. Avoid using highly concentrated compounds and do not over-process.