Ultra Pure Niobium

The business unit Special Metals Technology is specialised in the melting of high purity niobium ingots. In its pure form the metal niobium is used for high-frequency superconduction in the form of resonators, so-called cavaties. Fundamental to research in this area is the examination of subatomic particles (electrons, positrons, protons). The ingots distinguish themselves by possessing a high residual resistance ratio (RRR value of over 300) and can be processed into semi-finished goods such as blank sheets, seamless tubes or formed components which are of major use in high frequency superconduction applications.

RRR (Residual Resistivity Ratio) is used to ultimately measure the level of purity. It is the ratio between the electrical resistance at room temperature and the electrical resistance taken at the critical temperature. The latter being the temperature at which the sudden transition from conventional current to superconductivity occurs. The higher the RRR, then the better the quality of the niobium. Standard quality niobium has an RRR of between 20 and 40. The business unit Special Metals Technology smelts quality high purity niobium with RRR values of 300 and higher.

One of the newest technological trends is aiming to not only win the purest polycrystalline niobium possible, but also to release the metal from the smelting process with a large central intact grain. These coarse grain blocks can be directly cut into semi-finished goods for use in the production of resonators. From both polycrystalline and coarse grain blocks, the so-called ingots, semi-finished goods can be made to suit particular customer requirements.