joining together two materials by a mechanical interlock resulting from &# 34 ; chips &# 34 ; at their interface is disclosed . the chips , composed of one of the two materials to be joined or of a third material are partially embedded into the surface of the first material when that material is formed so as to form surfaces which &# 34 ; overhang &# 34 ; the first material . thereafter , the second material is formed against the overhanging surfaces of the chips to establish the mechanical interlock . this technique is particularly useful in anchoring a dissimilar material to a polymeric material having poor bondability and / or a high melt temperature , for example fluoropolymers , as illustrated by the forming of a liner for a pump casing , or the like , by rotational molding . in that illustration , small particles and chips are distributed uniformly over the surface of an enclosed mold heated to melt the particles and fuse the chips thereto , and cooled to form a layer with the chips projecting therefrom so as to provide an interlock when a casing is formed against the liner . other aspects of the present invention include the article of manufacture formed by the above method .