Method for passivating tantalum metal surface and apparatus thereof

Abstract

A method for passivating tantalum metal surface is provided, the method comprises cooling tantalum metal to or below 32° C. and/or passivating tantalum metal surface by oxygen-containing gas with a temperature of 0° C. or below. Also provided is an apparatus for passivating tantalum metal surface for applying the method, comprising a heat treatment furnace, an argon forced-cooling device and/or a device for cooling oxygen-containing gas.

1 . (canceled) 
     
     
         2 . A method for passivating tantalum metal surface, characterized in that it comprises following steps:
 a). providing tantalum metal which has been subjected to heat treatment;   b). lowering the temperature of the tantalum metal to room temperature;   c). introducing an oxygen-containing gas at 0° C. or below, preferably 0° C. to −40° C., to passivate tantalum metal surface; and   d). optionally repeating the step c) once or more.   
     
     
         3 . A method for passivating tantalum metal surface, characterized in that it comprises following steps:
 a). providing tantalum metal which has been subjected to heat treatment;   b). lowering the temperature of the tantalum metal to 32° C. or below, preferably below 30° C., and more preferably 10° C.-30° C., by using cooled inert gases;   c). introducing an oxygen-containing gas at 0° C. or below, and preferably 0° C. to −40° C. to passivate tantalum metal surface; and   d), optionally repeating the step c) once or more.   
     
     
         4 . A method of passivating tantalum metal surface according to  claim 2 , characterized in that the oxygen-containing gas is air, a mixture gas of inert gas and oxygen, or a mixture gas of inert gas and air. 
     
     
         5 . A method of passivating tantalum metal surface according to  claim 2 , characterized in that the oxygen-containing gas is air, a mixture gas of inert gas and oxygen, or a mixture gas of inert gas and air. 
     
     
         6 . A method of passivating tantalum metal surface according to  claim 2 , characterized in that the oxygen-containing gas is a mixture gas of argon and air. 
     
     
         7 . A method of passivating tantalum metal surface according to  claim 2 , characterized in that the concentration of oxygen in the oxygen-containing gas is 21 vol. % or below, preferably 5-20 vol. %. 
     
     
         8 . A method of passivating tantalum metal surface according to  claim 3 , characterized in that said inert gas is argon. 
     
     
         9 . An apparatus for carrying out the method of  claim 1 , the apparatus comprising a heat treatment furnace, the heat treatment furnace comprising: a hearth, a shell with a water-cooling jacket constituting the hearth, an inlet for the oxygen-containing passivation gas to enter the hearth, aeration pipelines, a heater arranged within the hearth, and a heat treatment crucible for accommodating tantalum metal to be treated; characterized in that the apparatus further comprises a refrigeration system for an oxygen-containing gas, the refrigeration system of an oxygen-containing gas comprising:
 an inlet of an oxygen-containing gas, which is used for receiving an oxygen-containing gas for passivating tantalum metal;   a heat exchange chamber, the oxygen-containing gas is cooled in the heat exchange chamber by means of heat exchange; and   an outlet of an oxygen-containing gas, the cooled oxygen-containing gas leaves the heat exchange chamber from the outlet and enters the heat treatment furnace from the upper part of the heat treatment furnace through thermal insulation connection pipelines.   
     
     
         10 . An apparatus for carrying out the method of  claim 2 , the apparatus comprising a hearth, a shell with a water-cooling jacket constituting the hearth, an inlet for oxygen-containing passivation gas entering the hearth, an inlet for argon entering into the hearth, an argon outlet positioned at upper part of the heat treatment furnace, a heater arranged within the hearth, and a heat treatment crucible for accommodating tantalum metal to be treated; characterized in that the apparatus further comprises an argon forced-cooling device and a refrigeration system of an oxygen-containing gas,
 wherein the argon forced-cooling device comprising:
 an inlet for argon to be cooled, the inlet for argon to be cooled being connected to the argon outlet at the upper part of the heat treatment furnace; 
 a heat exchange chamber, the heat exchange chamber receives argon at a high temperature from the heat treatment furnace by means of the inlet for argon to be cooled and cools it by heat exchange manner; 
 an outlet of cooled argon, the argon cooled in the heat exchange chamber being discharged from the outlet of argon; 
 a circulating pump, the circulating pump receives the cooled argon from the outlet of cooled argon, and supplies the cooled argon into the heat treatment furnace from the inlet for argon at the lower part of the heat treatment furnace through connection pipelines; 
   and wherein the refrigeration system of an oxygen-containing gas comprising:
 an inlet of an oxygen-containing gas, which is used for receiving an oxygen-containing gas for passivating tantalum metal; 
 a heat exchange chamber, the oxygen-containing gas is cooled in the heat exchange chamber by means of heat exchange; and 
 an outlet of an oxygen-containing gas, the cooled oxygen-containing gas leaves the heat exchange chamber from the outlet and enters into the heat treatment furnace from the upper part of the heat treatment furnace through thermal insulation connection pipelines. 
   
     
     
         11 . An apparatus for passivating tantalum metal surface according to  claim 10 , characterized in that the tantalum metal is cooled to 32° C. or below, preferably 10° C. to 30° C., by means of the argon forced-cooling device. 
     
     
         12 . An apparatus for passivating tantalum metal surface according to  claim 10 , characterized in that the refrigeration system of an oxygen-containing gas cools the oxygen-containing gas to provide an oxygen-containing gas for passivation at a temperature of 0° C. or below, preferably −40° C. to 0° C. 
     
     
         13 . An apparatus according to  claim 11 , characterized in that the refrigeration, system of an oxygen-containing gas cools the oxygen-containing gas to provide an oxygen-containing gas for passivation at a temperature of 0oC or below, preferably −40oC to 0oC