Abstract
The dimensional change during bonding and the transverse rupture strength of joints of iron powder compacts were investigated. Most compacts were 10 mm regular cubes produced by pressing a reduced-ore powder with 0.7 mass% of zinc stearate as a lubricant under 600 MPa, and sintered and bonded at 1130°C for 35 min in a single cycle heating process in hydrogen. Some were sintered at 1130°C for 60 min before bonding.
During bonding of green compacts on the pressed faces, the shrinkage increased in the pressing direction of bonding, while the expansion increased in the perpendicular one, with increase in the bonding pressure. The joint area and the transverse rupture strength increased with increasing bonding pressure in the low pressure range.
During bonding of green compacts on the side faces, the shrinkage increased in the pressing direction of bonding, while the expansion increased in the perpendicular one, with increase in the bonding pressure. And the width of microcracks perpendicular to the pressing direction which had originally existed in green compacts grew larger. It caused a remarkable expansion in the pressing direction and a decrease of the transverse rupture strength.
During bonding of sintered compacts on the side faces, the microcracks did not grow larger and the transverse rupture strength increased with increase in the bonding pressure.
