Fiber reinforced composite material and method for producing fibers for such material

A composite material, comprising fibers and a matrix material in which said fibers are embedded, each of said fibers having along its length first surface ring zones around the respective fiber with a first given adhesiveness or bonding ability and second surface ring zones around the respective fiber with a second adhesiveness or bonding ability higher than said given adhesiveness for providing different bonding abilities between the fiber surface and the embedding matrix material at said first and second ring zones along the length of said fibers, said second surface ring zones being interposed between said first surface ring zones along the length of the respective fiber for providing a crack stop characteristic at an interface between the fibers and said embedding matrix material at said first surface ring zones of lower adhesiveness.

A fiber reinforced composite material, comprising fibers selected from a group consisting of boron fibers, carbon fibers, graphite fibers, and silicon carbide fibers, and a matrix material in which said fibers are embedded, said matrix material being selected from a group consisting of aluminum, resin, and borosilicate glass, each of said fibers having along its length first and second surface ring zones around the respective fiber, each surface ring zone having one of first and second different bonding abilities for providing higher and lower strength bonds between the fiber surface and the embedding matrix material, said surface ring zones of higher and lower strength bonds alternating with each other along the length of said fibers for providing a crack stop characteristic at an interface between the fibers and said embedding matrix material at surface ring zones having said lower strength bonds.

A fiber reinforced composite material, comprising a matrix material of aluminum, and boron fibers embedded in said matrix material of aluminum, said boron fibers having first surface ring zones around the respective fiber, an adhesion reducing layer of aluminum oxide (Al.sub.2 O.sub.3) on each of said first surface ring zones, and second surface ring zones around the respective fiber, said second ring zones being free of said adhesion reducing layers for spacing said first surface ring zones from each other by said second surface ring zones along said fibers, said adhesion reducing layers providing a low or no bonding strength between the fibers and the matrix material, said second surface ring zones having a higher bonding strength between the fibers and the matrix materials for providing a crack stop characteristic at said first surface ring zones of low or no bonding strength between the boron fibers and the matrix material of aluminum.

A fiber reinforced composite material, comprising a resinous matrix material, and carbon fibers embedded in said resinous matrix material, said carbon fibers having first surface ring zones around the respective fiber, adhesion reducing means on said first surface ring zones, and second surface ring zones around the respective fiber intermediate said first surface ring zones, said adhesion reducing means providing a low or no bonding strength between said carbon fibers and said resinous matrix material, said second surface ring zones having a further bonding strength between said carbon fibers and said resinous matrix material, said further bonding strength being higher than said low or no bonding strength, for providing a crack stop characteristic at said adhesion reducing means on said first surface ring zones.

A fiber reinforced composite material, comprising a borosilicate glass matrix material and silicon carbide fibers embedded in said borosilicate matrix material, said silicon carbide fibers having first surface ring zones around said silicon carbide fibers, adhesion reducing means on said first surface ring zones, and second surface ring zones around said silicon carbide fibers intermediate said first surface ring zones, said adhesion reducing means providing a low or no bonding strength between said silicon carbide fibers and said borosilicate glass matrix material, said second surface ring zones having a further bonding strength between said silicon carbide fibers and said borosilicate glass matrix material, said further bonding strength being higher than said low or no bonding strength for providing a crack stop characteristic at said adhesion reducing means on said first surface ring zones.