Molding process for fiber reinforced glass matrix composite articles

Abstract

A method of making complex shaped (e.g. having curved surfaces or walls) fiber reinforced glass matrix composites by injection molding is described. The injection molding can take place by heating and injecting a mixture of glass powder and chopped fibers or whiskers directly into the mold, or a billet of glass matrix material containing the chopped fibers or whiskers made with a density approximately equal to the density of the final composite can be prepared first. In one embodiment the billet is formed by admixing a polymeric binder, glass powder, and a carrier liquid with the reinforcing fibers, drying the mixture, cold pressing the mixture to less than its original volume, and hot pressing to the density desired in the final product. Either the glass powder-chopped fiber or whisker combination or the formed billet is next placed in the injection molding apparatus where it is heated at least to the softening point of the matrix glass and injected into the predetermined mold shape. It is then allowed to cool to a temperature below the strain point of the glass and ejected or otherwise removed from the mold. In addition to providing a method of making fiber reinforced glass parts which can be automated and mass produced, articles are produced which have fiber orientation and strengths in three dimensions.