Niobium is used are as diverse as the properties of the material itself. We briefly present two of these below: In actual fact, niobium, like all other metals, is gray. However, by applying a passifying oxide layer, we allow our metal to gleam in a beautiful array of colors. But niobium is not just pretty to look at. Niobium Sheet / Plate standard is ASTM B393, Grade RO4200, RO4210 . Application: electronics, metallurgy, chemical, hard alloy cutters, aerospace and aviation.