Manufacturing Process for Large Sheets of Transparent Single Crystal Aluminum Oxide by the Czochralski Method

摘要

The Czochralski technique was developed for the growth of single crystal aluminum oxide in plate form for transparent armor applications. A description of the growth process is given along with an assessment of the optical quality. Growth was described for two plate sizes, and the problems associated with crystal growth for both sizes are discussed. With the intermediate size plate, particular emphasis has been placed on the improvement of crystalline shape and optical qualities. A plate in unfinished form with dimensions 4 in x 8 in x 1/2 in thick was grown successfully and forwarded to the government for their inspection. With the exception of in-line transmission towards the UV end of the visible spectrum, the optical properties for this plate fell well within the stated specifications for the material. Growth was carried out from the large crucible and a plate with approximate dimensions of 6 in x 6 in x 1/2 in thick obtained. The material was single crystal, although some further development work is required in order to improve the optical quality. The problems of fabricating the large size plate was considered and the development work along these lines described. (Author)