Reinforced shell mold and method

Abstract

A method of making a ceramic shell mold comprises repeatedly coating a fugitive pattern of an article to be cast with a ceramic slurry layer and applying on the ceramic slurry layer a refractory stucco to form a plurality of ceramic slurry layers and stucco layers on the pattern wherein at least one of the stucco layers is formed by applying discontinuous stucco fibers followed by applying a granular stucco particles on the discontinuous stucco fibers.

We claim:  
     
         1 . A method of making a ceramic shell mold, comprising repeatedly coating a fugitive pattern of an article to be cast with a ceramic slurry layer and applying on the ceramic slurry layer a refractory stucco to form a plurality of ceramic slurry layers and stucco layers on the pattern wherein at least one of the stucco layers is formed by applying discontinuous stucco fibers followed by applying a granular stucco particles on the discontinuous stucco fibers.  
     
     
         2 . The method of  claim 1  wherein the granular stucco particles are applied on randomly oriented discontinuous stucco fibers to pack the discontinuous stucco fibers down on the slurry layer underlying the discontinuous fibers.  
     
     
         3 . The method of  claim 2  wherein the granular stucco particles are applied on the randomly oriented discontinuous stucco fibers while the underlying slurry layer is still wet such that a majority of the packed down discontinuous stucco fibers stick to the slurry layer.  
     
     
         4 . The method of  claim 2  wherein the granular stucco particles are applied on the randomly oriented discontinuous stucco fibers to form a stucco layer comprising packed down discontinuous stucco fibers and the granular stucco.  
     
     
         5 . The method of  claim 4  wherein some of the granular stucco particles fill spaces between the packed down discontinuous stucco fibers.  
     
     
         6 . The method of  claim 1  wherein the granular stucco particles are applied by raining the granular stucco particles by gravity down on the discontinuous stucco fibers.  
     
     
         7 . The method of  claim 6  wherein the discontinuous stucco fibers and the granular stucco particles comprise the same or different ceramic material.  
     
     
         8 . A ceramic shell mold, comprising a plurality of ceramic flour layers and refractory stucco layers wherein at least one of the stucco layers comprises both discontinuous stucco fibers and granular stucco particles.  
     
     
         9 . The shell mold of  claim 8  wherein said at least one stucco layer comprises packed down discontinuous stucco fibers with the granular stucco on and between the fibers.  
     
     
         10 . The shell mold of  claim 9  wherein some of the granular stucco particles occupy spaces between the packed down discontinuous stucco fibers.  
     
     
         11 . The shell mold of  claim 8  wherein the discontinuous stucco fibers and the granular stucco particles comprise the same or different ceramic material.