Sputtering targets are used in vacuum vapor deposition machines as a source of the material to be deposited. A hot plasma or electron beam is used to blast material off the surface of a disk of material like this inside a vacuum chamber. The material is vaporized and travels through the vacuum to strike the surface of something you want to have coated. This is done very commonly with chromium and other shiny metals. I'm not sure why you'd want to do it with titanium, but I'm sure there's a good reason.
Source: eBay seller anish62
Contributor: Theodore Gray
Acquired: 10 February, 2007
Text Updated: 10 February, 2007