流動特性と射出成形性に及ぼすアルミナコンパウンド中のバインダー組成の影響

抄録

Alumina compounds with 20-40vol% powder concentrations in two mixture systems of organic binders were prepared to discuss their flow properties and feasibility for injection molding. The selected mixture systems (A) and (B) had the bonding resin/plasticizer/lubricant content ratio of 85/10/5 and 65/20/15, respectively. The results obtained were as follows:
All compounds showed a non-Newtonian flow and the type of flow could be characterized as shear thinning. Mixture system (A) flowed likely as a Bingham body, but (B) flowed as a pseudo-plastic body. The relation between apparent viscosity and powder concentration was well fit to Farris's Eq., and the inherent viscosity calculated was 8.3Pa·s for (A) and 1.1Pa·s for (B) at 165°C.
Mold inner pressure patterns during injection molding differed largely in two mixture systems (A, B). In the mixture system (A) the mold inner pressure less transmitted from the injection pressure, and the filling time was slower than in the mixture system (B).
Internal cracks appeared at the dewaxing stage, and their shape and size were influenced by the composition of organic binders.