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Ceramic material for use in casting reactive metals
| Details |
Inventors: Dodds, Gerald C.; Alexander, Ricky A.;
Assignee: PCC Airfoils, Inc. (Cleveland, OH)
Primary Examiner: Bell; Mark L.
Assistant Examiner: Sample; David
Attorney, Agent or Firm: Tarolli, Sundheim & Covell
An improved sintered ceramic core is used in a mold during the casting of a reactive metal. Prior to sintering, the core contains ceramic material which includes yttrium aluminate and alumina (Al.sub.2 O.sub.3). It is preferred to have the ceramic material contain between 10% and 40% yttrium aluminate. Prior to sintering, the yttrium aluminate has a mean particle size of less than 20 microns and, preferably, less than 10 microns. Particularly advantageous results has been obtained by using yttrium aluminate having a mean particle size, prior to sintering, of approximately 3 microns. It is contemplated that the ceramic material will be utilized to form other articles, such as a mold, filter, or liner for a ladle, which are exposed to reactive metals during casting. |
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DETAILED DESCRIPTION The present invention relates to an article surface, for example, a core surface, which is exposed to a reactive metal during casting of the reactive metal.
The article surface is formed from a ceramic material which, prior to sintering, includes yttrium aluminate and alumina (Al.
sub.
2 O.
sub.
3).
The ceramic material advantageously contains between 10% and 40% yttrium aluminate.
The yttrium aluminate has a mean particle size of less than 20 microns prior to sintering and preferably has a mean particle size less than 10 microns.
It has been found to be particularly advantageous to use yttrium aluminate having a mean particle size of approximately 3 microns.
During forming of the core or other article having a surface which is exposed to reactive metal during casting, a binder and the ceramic material which contains yttrium aluminate and alumina are mixed to form a compact.
Thereafter, at least a portion of the binder is removed by exposing the compact to water.
The compact is then sintered.
During sintering, the yttrium aluminate and the alumina interact to yield a ceramic body which subsequently prevents reactions from occurring between the resulting ceramic surface and a reactive metal.
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Manufacturing Materials 
