GB1452779A - Getter devices - Google Patents

Abstract

1452779 Gettering SAES GETTERS SpA 14 Dec 1973 [14 Dec 1972] 58037/73 Heading H1D A getter device comprises a metallic or ceramic foraminated support 20, which consists of a threedimensional network 21 which defines a plurality of inter-connecting cavities, and has powdered getter material contained in at least a part of the network. The getter materials may be evaporable, e.g. Ca, Sr, Mg and Ba, and alloyed with other metals, the particulate alloy being mixed with another particulate metal which reacts with the alloy on heating to release the getter by exothermic action. Alternatively the getter materials may be non-evaporable, e.g. Ti, Zn, W, Th, V, Ta, Nb, Hf and V, and may be alloyed with e.g. Al, Ce, Mn or mixed in divided form, e.g. a mixture of Ce and La. For use at temperatures from room temperature to about 400‹C, the particulate getter may be mixed with an anti-sintering agent such as graphite, or with a particulate Zr-Al alloy. Refractory oxides or carbides may be added. If the cavities are large, the powder is poured in, with mechanical or ultrasonic vibration as required. It is preferred, however, to form a suspension of the powder in a liquid and to immerse the support therein. The support is then heated to 800-1200‹C. As shown, the foraminated block 20 is filled with powdered Zr ( a non- evaporating low temperature getter) mixed with powdered Zr-Al alloy. Alternatively, a foraminous Ni-Cr alloy block is filled with Zr powder mixed with graphite powder. In a particular example, particles of Zr and graphite form a suspension in ethanol, and a foraminated disc of Ni-Cr alloy is immersed therein, and then placed in vacuum of 10<SP>-5</SP>-10<SP>-6</SP> torr. The temperature is increased over 25 minutes to between 800 and 1100‹C, and maintained at that temperature for 5 minutes. The disc is then allowed to cool to room temperature. The getter is placed in its evacuated enclosure and activated by heating to 900‹C for 10 minutes. The graphite may be replaced by Zr-Al alloy. In experiments, the getter was tested for absorption of gas. A cylinder of foraminated Ti was filled with getter and heat treated. When argon and hydrogen were passed through the getter, the impurity content was reduced.