Strengthening a ceramic by post sinter coating with a compressive surface layer
 Strengthened ceramic and a method for increasing the mechanical strength of fully sintered ceramic articles, in particular alumina type ceramic and glass-ceramic articles. Such articles are strengthened by forming a compresssive material layer of amorphous silicon dioxide or refractory metal nitride on the surface of the article to be strengthened. 
International Business Machines Corporation
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Donald J. Jungihl Da-Yuan Jae M. Steven G. Hung-Chang Charles H.
Hunt Kim Shih Park Barbee Huang Perry