Abstract
Compacting pressures similar to those for P/M parts were applied to alumina-based ceramic granules, which were produced for IC-substrates, to investigate the spring-back during compacting and the shrinkage during sintering. Cylinders, d10 × h10 mm, were compacted with die-wall lubrication under 50-800 MPa. They were heated in air at the rate of 3.5°C/min, and held at 600°C for 10 min for dewaxing and at 1400°C for 2 hr for sintering.
The axial spring-back was measured with a couple of electric micrometers attached to the punches. The radial spring-back was derived from the diametral difference between the die and the compact.
The spring-back of the granules was larger than those of the iron and copper powders. Increased compacting pressure led to increased green density, accompanied by increased axial spring-back by the unloading and decreased axial spring-back by the ejecting. It also led to decreased shrinkage in both directions during the sintering.
