RIESENKÖRNER UND EINKRISTALLE AUS CHROM UND IHRE HERSTELLUNG

摘要

A giant particle and a single crystal of chromium are produced by sintering Cr containing 0.0002-0.1 wt.% in terms of their oxides of Ti, Al, Si and/or Ca and optionally 0.01-3 wt.% of Co and heat-treating it. The sintered chromium can be given a desired shape before the heat-treatment. The sintering can be carried out for 10 mins. or longer under pressure (1000 atm or higher) at a temp. between 1200 deg. C and the m.pt. of Cr. The shaping is carried out by hot-rolling, moulding, or pressing. The temp. of hot-rolling is 700 deg. C or lower and the rolling percentage is 30-90%. The heat-treatment (sec. crystallisation) is carried out at 1300-1860 deg. C (the m.pt. of Cr) for pref. 30 mins. or longer. However, when Cr contains Co, which functions as a catalyst, the heat-treatment is carried out at 1300 deg. C.