In his case study Exploring and understanding non-thoriated GTAW electrodes, Michael Fletcher from Delta Consultants explains how in non-consumable electric arc welding, very high temperatures are generated. While tungsten has a high melting point and is potentially a good electrode material, the pure metal is unsuitable because of poor arc starting, instability, and high electrode wear.
While early research showed that the addition of thoria to the tungsten resulted in overall improvements in performance, it has been recognized that the use of thoriated products presents a health hazard, as the dust created during use and grinding is radio-toxic, Fletcher writes. A range of tungsten electrodes containing alternative oxide additions or dopants have been developed, which are referred to as multivariate electrodes.
For the full article, please email Catarina Muia at c.muia@kci-world.com for the article PDF.