Perforated laminated material

A perforate laminated material comprising first and second abutting sheets of high temperature resistant material having abutting surfaces bonded together in face-to-face relationship, each of the said sheets being provided with a plurality of perforations, the perforations in the adjacent sheets being out of alignment, at least one of the abutting surfaces of the sheets being provided with channels defining passageways in the material interconnecting said perforations of said first sheet with said perforations in said second sheet, said perforations in said first sheet being operable to meter the flow of a cooling fluid successively through said first and second sheets, whereby discrete flows of fluid pass through said perforations in said first sheet and impinge upon the inside surface of said second sheet, the total cross-sectional area of the perforations in said second sheet being at least double the total cross-sectional area of the perforations in the first sheet in a predetermined area of material whereby the velocity of the fluid passing through said second sheet perforations is less than that passing through said first sheet perforations and the fluid emitted from said second sheet perforations, tends to coalesce and substantially produce a film of fluid adjacent to the outer surface of said second sheet over said predetermined area.