Kerosene immersion or ultrasonic cleaning is preferred for tantalum alloy tube billet, so that the surface of the material after cleaning is metallic and shiny, and the internal and external surfaces are free from oil pollution, impurities and other foreign pollutants. It is then subjected to vacuum heat treatment.
The tantalum alloy tube billet after vacuum heat treatment is optimized for surface oxidation treatment. The surface oxidation treatment produces a dense and high-priced oxide film on the surface, so as to avoid surface damage caused by the friction of the substrate and improve the friction during the drawing process. The optimal heating temperature of the surface oxidation treatment is 180°C~700°C, and the optimal time of the surface oxidation treatment is 2min~70min. The surface oxidation treatment preferably adopts box-type or well-type resistance furnace and is carried out in an atmospheric environment. The tantalum alloy tube billet after surface oxidation treatment is preferably pickled to remove surface impurities. The optimal solution of pickling is nitric acid and hydrofluoric acid, the optimal volume ratio of nitric acid and hydrofluoric acid is 20: (2~3), the concentration of nitric acid is 68wt%, the concentration of hydrofluoric acid is 50wt%. The pickling tube billet was preferably burned. The burning can decompose and wave the residual foreign pollutants on the inner and outer surfaces of fine diameters, especially the residual foreign pollutants on the inner surfaces, under the condition of medium-temperature extremely high vacuum negative pressure, so as to improve the cleanliness of the pipe. The burning is preferably carried out in the vacuum annealing furnace, the vacuum degree is preferably <1.6 X 10-3Pa, the temperature is preferably 450 °C~550 °C, and the time is preferably 20min~60min.
In order to make the tantalum alloy tube billet have better surface quality and comprehensive performance, the invention optimally adds oxidation treatment and burning on the material surface after emulsification. The present invention, in the process of preparation of tantalum alloy, in turn, has carried on the line - and hot - coating oxidation coating - heat - extrusion - vacuum heat treatment - milk - processing of vacuum heat treatment process, uniform deformation of tantalum alloy ingot, and avoids the process of material is not polluted, make preparation of the surface of the material quality is better and higher mechanical performance.
