NI-BASE ALLOY POWDER FOR THERMAL SPRAYING AND ITS PRODUCTION

摘要

PURPOSE:To stably manufacture an alloy powder of superior quality for thermal spraying in high efficiency, by melting an Ni-base alloy material of low oxygen content in a crucible made of special oxide refractory under an inert-gas atmosphere and then by atomizing the resulting molten alloy while avoiding reaction with moisture or air. CONSTITUTION:The inside of a melting furnace 11 is filled with inert atmosphere, and the crucible 12 composed of an oxide refractory difficult to be dissociated or reduced is provided to the inside of the furnace 11. The Ni-base alloy with low oxygen content is melted in the crucible 12, and the resulting molten alloy is poured into a tundish 13 composed of the same material as mentioned above, which is allowed to flow down through a nozzle 13a composed of the same material as mentioned above into an atomizing chamber 14 to undergo powdering by means of a high-speed stream of inert gas. Heaters 15 are provided onto the external wall of this chamber 14, by which moisture and air sticking to the inner wall 14c are evaporated and discharged from the chamber 14. In this way, the spherical powder of Ni-base alloy for thermal spraying having =2,000ppm oxygen content, =0.45 apparent density ratio, and =21sec/50g flow velocity can be obtained.