Metal Diffusion Techniques and Class Sealing Problems in the Electron Tube Industry
TL;DR: In this paper, the early techniques of chrome diffusion and the more recent methods of chromizing of metals are discussed, as well as their effect on the coefficient of thermal expansion and the interface between glass and metal.
Abstract: Summary-- This paper deals with early techniques of chrome diffusion and the more recent methods of chromizing of metals. Historical applications of the process as applied to certain glass sealing metals, its effect on the coefficient of thermal expansion and the interface between glass and metal, as well as proper seal geometry, are discussed. Precleaning, oxide formation, glass application, seal types, and postremoval of the oxide are explained.
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TL;DR: The thermal stability of chromized molybdenum depends on the nature of the diffusion coating, which is affected by the chromizing method and the composition of the powdered mixture as discussed by the authors.
Abstract: 1.
We investigated the thermal stability of molybdenum chromized by different methods. Molybdenum chromized by the gas method in a powdered mixture consisting of 70% Cr+25% Al2O3+5% NH4Cl had the highest thermal stability.
2.
The thermal stability of chromized molybdenum depends on the nature of the diffusion coating, which is affected by the chromizing method and the composition of the powdered mixture. The diffusion zone, consisting of a solid solution with a high chromium concentration at the surface, has a fairly high level of thermal stability, while the presence of nitride (Cr2N) lowers the thermal stability.
3.
We determined the relationship between the thermal stability of chromized molybdenum and the thickness of the diffusion coating and the surface finish.
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