Disclosed is a process of surface hardening for titanium alloys comprising .alpha. phase by carburization in a molten salt which consists of carbonate as the carbon-yielding agent with electrolysis within 790.degree. C. to 930.degree. C. The hardness within the effective carburizing layer is influenced by bath temperature, applied current density and carburizing period. The major hardening effect is due to the formation of solid solution of carbon in .alpha.-Ti.

There is formed a silicon-base antimigration barrier layer by projection, on a hot surface of a glass object, in an unconfined ambient atmosphere from a gaseous mixture comprising neutral gas, a silicon precursor, typically a silane, between 10 and 60% of ammonia and preferably less than 5% oxygen, the ratio of the oxygen and silane contents being comprised between 0 and 4. It is useful particularly for the treatment of sodium-calcium glass receptacles to prevent migration of ions into liquids contained in the receptacles.