Coating Quartz Samples by Metallic Titanium in Molten Salts

摘要

Different possibilities to coat quartz samples by metallic titanium in molten NaCl-KCl salts are discussed in the present paper. The most straightforward way to coat quartz by Ti is to bring it to direct contact with metallic Ti in the molten salt. In this case the deposit was obtained only in the region of contact; in regions far froni the place of the contact Ti-deposit was not obtained at all. The second possibility to coat quartz by Ti is to shift the equilibrium in the Ti/NaCl-KCl system containing ions of different valences (Ti~(+2) - Ti~(+3) - Ti~(+4)) towards the higher valences, by adding NaF into the system, leading to the formation of dispersed metallic Ti. However, due to high corrosion rates of quartz in the presence of NaF no traces of Ti were found on the surface of the quartz sample in this case. Thin, homogeneous, shiny metallic coating has been obtained on quartz when Ti~(+2) ions were constantly added into the melt by anodic dissolution of Ti in NaCl-KCl melt (with a quartz sample having no direct contact with the Ti anode or with the cathode). The electroless deposition of the Ti-coating on quartz in this case is accompanied by the formation of TiSi_2 intcrmetallic compound, with the formation of the double-coating: quartz/TiSi_2/Ti.