The NRNU MEPhI Department No. 9 “Physical Problems of Materials Science” project led by Oleg Nikolaevich Sevryukov, “Effect of the compositions of rapidly quenched active filler alloys and high-temperature brazing regimes on the thermomechanical properties of metal-ceramic joints”, has won the “Fundamental and Exploratory Scientific Research by Individual Research Groups” competition, organised by the Russian Science Foundation (RSF) in 2025. The project is devoted to creating new precision filler alloys that will be used to join advanced ceramics with metals.
Metal-ceramic joints are widely used across various industries. Metal-ceramic assemblies are used in the electronic, radio-electronic and electrical engineering industries, where they serve as housings for electrovacuum and semiconductor devices, hermetic switches, vacuum-tight connectors, electrical and optical vacuum feedthroughs, insulators and similar components. The most common pairing for producing such joints is 29NK alloy and alumina ceramic (often VK94-1 or VK100 grade ceramics). The rapid development of technology increases the operational requirements for such structures every year. Among these requirements are hermeticity and thermal resistance at operating temperatures, as well as the mechanical strength of the joints. Research into producing metal-ceramic joints dates back to the 1940s. At that time, the main research focus was developing a method for metallising ceramics with refractory-metal powders through firing, followed by brazing of the metallised ceramic. This technology involves multiple steps. The main achievement of this period was the industrial introduction of pastes consisting of 80–90% molybdenum/tungsten and 10–20% manganese with silicon additives. This technology remains the primary method for producing metal-ceramic joints at most enterprises today. Further development in this field led to the need to simplify the existing multi-step technology for producing metal-ceramic joints. This became achievable through the active brazing method, which is a single-step process. The essence of this method lies in using filler alloys doped with active elements (Ti, Zr). The active additives promote interaction between the filler alloy and the ceramic surface through redox reactions, ensuring wetting of the ceramic. However, there is limited and unsystematised data on the properties of brazed joints produced using such filler alloys. Sevryukov’s project plans to develop and produce 6 compositions of rapidly quenched filler alloys based on Ag, Cu and Ag-Cu, with Ti and Zr additives, for creating hermetic metal-ceramic joints between 29NK alloy components and VK100 ceramic. The work will study the effect of the brazing temperature-time regime on the interaction zones in the braze joint area. To study the thermal resistance of the joints, a structure will be used consisting of a cylindrical ceramic vessel brazed to a metal plug using a ceramic compensator. It is known that the design of the assembly significantly affects the ability to obtain hermetic joints, owing to stresses arising during cooling after brazing. Accordingly, finite element calculations will be carried out to optimise the design of the specimens used for hermeticity and thermal-resistance testing, in order to minimise stresses in the braze joint area. Using these specimens, the relationship between the number of hermetic joints and the number of thermal cycles will be established. Shear tests will be carried out to determine the mechanical properties of the brazed joints produced under different brazing regimes. This data will expand the body of knowledge on the formation of the structural-phase state of metal-ceramic joints during active brazing using rapidly quenched silver- and copper-based filler alloys, and will allow assessment of the effect of filler alloy compositions and brazing parameters on the complex stress state, strength and thermal resistance of the specimens.