US 4,051,272 A · Low-temperature thermionic emitter

Abstract

An improved photodelineatable cathode material is disclosed comprising a combination of triple carbonate (TC) and a hydrocarbon polymeric photoresist PR. A mixture of TC powder and PR is applied to a cathode by spraying, spinning or dipping and is then subjected to activation at a temperature from about 800.degree. C up to the melting temperature. The cathodes can be activated at a temperature as low as 800.degree. C and still deliver a 0-field, temperature-limited current density of 750 milliamperes per sq. centimeter at 600.degree. C. If a pattern is desired, the coating is exposed through a suitable mask to actinic light to harden the photoresist in the desired areas. Following exposure, the exposed image areas are developed and the unexposed portions of the coating are removed with solvent. When dry, the cathode is ready for activation.

Claims8

Dependent claims

A method of forming a low temperature thermionic emitter comprising the steps of:

a. forming a layer comprising a mixture of a pyrolitically decomposable alkaline earth oxide precursor dispersed in an actinically hardenable organic binder photoresist resin on the surface of a conductive substrate, said dispersion containing from 15% to 75% by weight of said precursor based on resin solids;
b. exposing said layer to actinic radiation to harden said binder;
and
c. heating said layer to a temperature sufficiently high to pyrolitically decompose said precursor and volatize said binder, said precursor being primarily reduced by the carbon remaining in said layer after said binder has volatized, to form a porous alkaline earth oxide containing coating on said surface.

1 more element

Dependencies are inferred from the claim text.

Low-temperature thermionic emitter

Life of this patent

Low-temperature thermionic emitter

Life of this patent

Abstract

Claims8