Composite materials

A composite material which is curable to form a panel that is not penetrated by a lightning strike, said composite material being made by a method comprising the steps of:

• providing a resin formulation comprising polymeric resin and electrically conductive particles dispersed therein wherein the amount of said electrically conductive particles is such that said resin formulation is electrically non-conductive;
• and
• combining said resin formulation with at least four carbon fiber layers to form said composite material which comprises at least four carbon fiber layers having interleafs located therebetween, said interleafs comprising said polymeric resin and said electrically conductive particles wherein the thickness of said interleafs between said carbon fiber layers is such that electrically conductive bridges are formed across said interleafs to electrically connect said carbon fiber layers together wherein said electrically conductive bridges each comprises an electrically conductive particle which has a particle size that is substantially equal to the thickness of said interleaf and wherein the number of said electrically conductive bridges is sufficient to prevent penetration of said composite material by a lightning strike once said composite material has been cured to form said panel.