High-porosity coated getter

Abstract

The importance of nonevaporable getters is recognized by the increasing number of various applications in vacuum technology. To meet some specific requirements of certain applications (e.g., special vacuum tubes) a nonevaporable getter layer (from a few tens to 100 μm or more) having high porosity (50%–60%) and very good gas sorption and mechanical characteristics has been developed. The special method used for the preparation of these getters produces gettering surfaces on conductive substrates of many different preformed shapes (very thin strips, cylinders, wires, etc.). This allows accomodation of the getters in special or restricted spaces. These results are reached by depositing on the substrates a mixture of powdered Ti (or Zr) and a nonevaporable getter alloy of the types: Zr–Fe–V or Zr–Al. The getter material is then partially sintered to obtain a good mechanical stability, keeping a relatively high porosity. The present paper describes the characteristics of the recently developed high-porosity coated getters in terms of their physical features (porosity, mechanical behavior in different working conditions, such as high H2 gas load, etc.) and sorption performances for some main gases under different activation conditions (from 300 to ∼750 °C), also making some comparisons with an evaporated Ti layer.