| 摘要 |
Shaped parts are formed from a powder having the desired chemistry of the finished part by mixing the powder with a thermosetting condensation resin that acts as a binder. The resin may be partially catalyzed, or additives or surfactants added to improve rheology, mixing properties, or processing time. Upon heating, the inherently low viscosity mixture will solidify without pressure being applied to it. A rigid form is produced which is capable of being ejected from a mold. Pre-sintered shapes or parts are made by injection molding, by using semi-permanent tooling, or by prototyping. Binder removal is accomplished by thermal means and without a separate debinding step, despite the known heat resistance of thermosetting resins. Removal is due to the film forming characteristic of the binder leaving open the part's pores, by providing oxidizing conditions within the part's pores as the part is heated, and by insuring that the evolving resin vapor diffuses through the pores by heating the part in a vacuum. |
