Abstract
The kinetics of dispersion of thin nickel-silver films deposited onto alumina and zirconia ceramics and annealed in vacuum at temperatures up to 1000 °C with different exposition times at each temperature (from 5 up to 20 min) was studied. The double films consisted of two layers: the first metallization layer was 150 nm nickel nanofilm deposited onto the oxide surface, and the second silver layer 1.5 mm thick deposited over the first one as a solder was used for joining of metallized oxide samples. It was found that these films remain rather dense during short-term heating up to 900 °C; and, after annealing at 950 °C and 1000 °C, they decompose immediately into individual droplets covering more than half the area of the ceramic substrates. The kinetic curves for the dispersion of these films were plotted.
Highlights
Joining ceramic materials with each other and with metals is carried out by two main methods: 1) brazing with molten metallic solders [1]-[3]; 2) solid-phase pressure welding [4]-[6]
With further annealing during ten minutes, the dispersion of the film increased (Fig. 3, b; 2); and after twenty minutes the dispersed silver film covered about 70 % of the whole surface of the nickel metallization coating on the ceramic specimen surface (Fig. 3, c; 2)
Studies of the behavior of double nickel-silver thin films deposited onto samples of alumina and zirconia ceramics during annealing found that such films b c
Summary
Joining ceramic materials with each other and with metals is carried out by two main methods: 1) brazing with molten metallic solders [1]-[3]; 2) solid-phase pressure welding [4]-[6]. In literature there is information on the use of twoand multilayer metal coatings in production of aircrafts, in structures to be implanted into the human body, in devices for flat displays, light-emitting devices and solar panels, in friction units, as sensitive elements of strain gauges, in erosion-resistant coatings of blades for engines of various purposes, as coatings for cutting tools and machine parts [13]-[18] The structure of such two- or multiphase coatings, determination of the optimal ratio of the thickness of each layer, processes of interaction at the phases interface, including the ceramic phase, is an important area of research. The study of two-layer nickel-silver coatings (films) on oxide materials during annealing in vacuum and the creation of brazed and welded oxide ceramics joints based on them with super-thin brazed seam, the thickness of which does not exceed 5 μm, is the main task of the present work
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