High-purity sponge titanium material and its production method

Abstract

The object of the present invention is to economically produce a high-purity sponge titanium material containing fewer amounts of oxygen and metal elements. To realize this object the vacuum separation time t in a vacuum separation step is t=t o +(15˜35) hour where the time t is the vacuum separation time in a vacuum separation step and t o is defined as the time from the start of the vacuum separation till the time when the temperature of the central part of the material in a reaction vessel reaches a stable temperature. At and near the central part of the material where the amounts of metal elements are small, the specific area measured by the BET method is 0.05 m 2 /g or less. Thus, even if the cutting and crushing of the material are performed in the atmosphere, the amount of oxygen in the cut and crushed material can be suppressed to a low level.

1 . A high-purity sponge titanium material produced by Kroll method wherein a specific area measured by the BET method is set at 0.05 m 2 /g or less and the content of respective metal elements of Fe, Ni, Cr, Al and Si is set at 10 ppm or less.  
     
     
         2 . A production method of a high-purity sponge titanium material of the present invention is one in which when a sponge titanium material is produced by Kroll method, the vacuum separation time t in a vacuum separation step is set at t=t o +(15˜35) hour while defining t o  as the time from the start of vacuum separation till the time when the temperature Tc of the central part of the material in a reaction vessel reaches a stable temperature To near the furnace temperature, and after the completion of vacuum separation, a part at and near the central part other than the upper part, the lower part and the outer circumferential part of the material in the reaction vessel is commercialized.  
     
     
         3 . A high-purity sponge titanium material according to  claim 1  wherein the amount of oxygen of cut and crushed high purity sponge titanium material is 200 ppm or less.  
     
     
         4 . The production method of the high-purity sponge titanium material according to  claim 2 , wherein said high-purity sponge titanium material has a specific area measured by the BET method of 0.05 m 2 /g or less and a content of respective metal elements of Fe, Ni, Cr, Al and Si of 10 ppm or less.  
     
     
         5 . The production method of  claim 4 , wherein an amount of oxygen of cut and crushed high purity sponge titanium material is 200 ppm or less.