Composite fabrication process to achieve flatness

Abstract

A method and a HIP can structure for hot isostatically pressed (HIP) production of flat sheet metal matrix composites having a dimension greater than about 4×5 inches. The HIP can is constructed so that most of the expensive components are reusable for further processing of other composites. The side walls of the HIP can have reduced thickness relative to the top and bottom walls and the can has a reinforced centerpiece between the two composites used in the example. Molybdenum foils are utilized to separate the composites from the stiffening structure so that when the HIP can is opened by breaking the weld at one of its wings, the components of the can and the composites come apart so that the most expensive structural members of the HIP can be reused.

What is claimed is: 
     
       1. A hot isostatic press method for forming flat sheet metal matrix composites having a dimension greater than 4×5 inches, the method comprising the steps of: providing at least one mat having aligned reinforcing fibers;   plasma spraying the at least one mat with a matrix metal to form at least one monotape structure;   providing at least one slab of metal having a high melting point and two flat parallel sides;   disposing at least one monotape structure, on each of the two flat parallel sides to form a generally symmetric assembly;   enclosing the symmetric assembly symmetrically within a HIP can enclosure having a top and a bottom and two side walls;   sealing the HIP can;   evacuating the HIP can enclosure; and   subjecting the canned assembly to a hot isostatic press process such that at least one essentially flat metal matrix composite structure is formed.   
     
     
       2. The method of claim 1 further comprising the step of: removing the composites from the can and from the slab of metal.   
     
     
       3. The method of claim 1 wherein the two side walls are thicker than the top and bottom walls. 
     
     
       4. The method of claim 3 wherein the side walls are about twice as thick as the top and bottom walls. 
     
     
       5. The method of claim 1 wherein the formed metal matrix composite structure is flat to within about 0.010 inches at a distance of about 0.25 inches from the edge. 
     
     
       6. The method of claim 1 wherein the formed metal matrix composite structure is flat within about 0.020 inches with the largest deviation being about 0.5 inches at the edge. 
     
     
       7. The method of claim 6 wherein the formed metal matrix composite structure is flat to within about 0.01 inches at distances greater than 0.5 inches from the edge.