Liapina K. Development of technological fundamentals of producing porous and powderlike metallic materials by the method of their vacuum deposition in vapours of alkali metal halogens

The work is devoted to establishing the features of the influence of the conditions of vacuum deposition of metals in the presence of alkali metal halogenides on microstructural features of the condensates and development on their basis of methods to produce porous and unconsolidated (powderlike) materials for functional purposes. Proceeding from the conducted investigations of microstructural characteristics of metal condensates at their simultaneous deposition with alkali metal halogenides, depending on substrate temperature, ratio of vapour flows and deposition rate, it was established that metal condensates with a porous structure form at the ratio of salt/vapour flows smaller than 0/5 and substrate temperature above that of salt melting. In the case of metals, which have no polymorphous transformations, the characteristics of the porous structure of the condensates have a non-monotonic dependence on substrate temperature, and metals with polymorphous transformations have a monotonic dependence. A method is proposed to produce materials with controllable characteristics of the porous structure (type of porosity (closed or open), pore shape, average size and total porosity). Such a method can be used in producing materials for implants (for instance, a stent), or their coatings, the porous structure of which can ensure absorption of the necessary volume of pharmacological preparation, and its gradual release into the biological environment, thus improving the process of their implantation. It is shown that at the ratio of salt/metal vapour flows greater than 0.5 and substrate temperature lower than that of salt and metal melting, it is possible to form encapsulated into the salt matrix metal powder with a small dispersion of dimensions of nano-scale particles resistant to agglomeration and interaction with the environment. A method is proposed of producing nano-sized powders of metals and their compounds, allowing their long-term storage under atmospheric conditions.