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M. I. Grechanyuk, V. G. Grechanyuk, V. A. Shapovalov, I. M. Grechanyuk, O. V. Matsenko, A. V. Kozyrev, and V. I. Gots
Massive Microporous Composites Condensed from the Vapour Phase
0883–0894 (2022)

PACS numbers: 61.43.Gt, 62.23.Pq, 81.05.Rm, 81.10.Bk, 81.15.Gh, 81.40.Lm, 81.70.Bt

The problems of microporous condensed materials obtained from the vapour phase are discussed in this article. The influence of the secondary-phase amount on the pore sizes and the pore-sizes’ dependence on the deposition temperature as well as on conditions, under which they are regulated, are shown. As established, the creation of materials with adjustable open porosity is possible with a content of refractory nanoparticles of not less than 4 wt.% and a deposition temperature of not less than 600°C. The concentration of the refractory phase has a significant effect on the volume and size of the pores; so, increasing the concentration of the refractory phase at a constant substrate temperature increases the probability of interaction of condensed atoms of the refractory compound. An increase of the annealing temperature leads to an intensification of pore fusion processes. With increasing annealing time in vacuum, a significant part of the porosity turns into open porosity in condensates containing 20–30 wt.% Al₂O₃. As shown, the coalescence processes of the pores are completed after 25 hours of annealing in vacuum at a temperature of 1200°C. As a secondary phase, it can be used such inclusions as oxides, fluorides, sulphides. The salt content in the titanium matrix of more than 45 wt.% is undesirable, because it violates significantly the continuity of the material. Therefore, the average pore size depends significantly on the deposition temperature and the annealing time of the condensates in vacuum. Open porosity can be adjusted in the range 0–50% of the total porosity with average pore sizes from 0.1 to 8 μm. As proved, the open porosity prevails at higher substrate temperatures in the relative balance of open–closed porosities. In addition, the physical and mechanical properties of condensate after exposure in water and after vacuum annealing are presented. Concentrations of refractory particles over 10 wt.% in the porous composite leads to significant deterioration of plasticity and strength. Vacuum annealing increases significantly the strength. Compacted microporous materials can be applied as coatings on the surface of any shape or in the form of precursors up to 6 mm in thick and up to 1 m in diameter.

Key words: electron-beam equipment, evaporation–condensation method, melting of metals and alloys, vapour-condensed composite materials, open porosity, shadow zones.

https://doi.org/10.15407/nnn.20.04.883