Sintered objects made from chromium powder - with through-holes formed by ceramic tubes, or by steel rods which are dissolved by acid after sintering

摘要

A metal sheath or casing, which contains one or more tubes or rods located between two opposite surfaces of the casing, is filled with Cr powder. The casing is then evacuated, sealed so it is gastight, and subjected to a gas pressure of 700-3100 bars while being heated at 1300-1460 deg. C. The sealed casing is pref. subjected to 1200 bars at 1340 dec. C. The rods in the casing are pref. made of steel, and are dissolved out of the sintered prod. so the latter contains one or more through holes. Alternatively, ceramic tubes, esp. alumina tubes, are used and are left in the sintered prod. so through holes are obtd. with an alumina wall. Sintered Cr objects can be made contg. through holes with a length:dia. ratio exceeding 10:1.