Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia
I. G. Gun, Dr. Eng., Prof., Dept. of Technology, Certification and Service of Automotives, e-mail: tssa@magtu.ru
E. G. Kasatkina, Cand. Eng., Associate Prof., Dept. of Technology, Certification and Service of Automotives, e-mail: kasatkina_tssa@mail.ru
I. Yu. Mezin, Dr. Eng., Prof., Head of the Dept. of Technology, Certification and Service of Automotives, e-mail: i.mezin@magtu.ru
A. S. Limarev, Cand. Eng., Associate Prof., Dept. of Technology, Certification and Service of Automotives, e-mail: aslimarev@mail.ru

The paper analyzes the influence of platinite wire parameters on its functional properties. Platinite is a bimetallic composite material for special purposes, including a core made of precision iron-nickel alloy 43N and an outer shell made of electrical copper. The parameters being studied are the coefficient of linear thermal expansion (CLTE), the value of which is influenced by the thickness of platinite components and the presence of an oxide layer on the wire surface. In this work, a functional property is understood as the possibility of forming a vacuum-tight junction of platinite with glass. The study of regularities of influence of platinite wire thickness variation on CLTE was carried out by the method of theoretical analysis and design experiment. Test calculations were carried out using the analytical dependencies obtained during the theoretical study, taking into account the information on physical and mechanical properties of the materials under study. It is noted that the actual value of CLTE of platinite is sensitive to two factors: the nickel content in the core material and the mass fraction of copper in the composition. Dependencies are presented that make it possible to calculate the numerical values of the mass fraction of copper in the directions of the maximum and minimum thickness of the shell, which determine the radial thermal expansion of the composition in these directions and reflect the unevenness of the thermal deformation of the cross-sectional contour as a whole. The analysis showed that even full compliance of platinite quality with the requirements of current regulatory documents does not exclude the appearance of defects in the form of glass coming off or cracking even at the stage of device manufacturing. The possibility of loss of tightness of electrovacuum devices during further operation is also not excluded.

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