US 7,368,406 B2
Whisker-reinforced ceramic containing aluminum oxynitride and method of making the same
Russell L. Yeckley, Latrobe, Pa. (US); and Shanghua Wu, Latrobe, Pa. (US)
Assigned to Kennametal Inc., Latrobe, Pa. (US)
Filed on Sep. 23, 2005, as Appl. No. 11/234,013.
Application 11/234013 is a division of application No. 11/101260, filed on Apr. 07, 2005, granted, now 7,262,145.
Application 11/101260 is a continuation in part of application No. 10/831383, filed on Apr. 23, 2004, abandoned.
Prior Publication US 2006/0030474 A1, Feb. 09, 2006
Int. Cl. C04B 35/81 (2006.01); C04B 35/515 (2006.01); C04B 35/577 (2006.01)
U.S. Cl. 501—95.3  [501/92; 501/96.1] 30 Claims
OG exemplary drawing
 
1. A process to make a ceramic body comprising the steps of:
providing a starting powder mixture comprising ceramic whiskers, a ceramic additive powder other than aluminum oxynitride, and aluminum oxynitride powder that contains less than or equal to about 0.1 weight percent aluminum nitride wherein the aluminum oxynitride powder is made by a process comprising the steps of: forming a powder mixture by mixing alumina powder and aluminum nitride powder according to the following formula: ((4−x)/3) alumina and x aluminum nitride wherein x is in mole percent and ranges between about 0.31 and about 0.61; adding between about 0.1 mole percent and about 1.0 mole percent of pure aluminum powder to the powder mixture; and reacting the powder mixture containing aluminum at a temperature between about 1600° C. and about 1900° C. for a duration between about 2 hours and about 24 hours in a flowing nitrogen atmosphere so as to form aluminum oxynitride;
consolidating the starting powder mixture into the ceramic body, and wherein the ceramic body having a Vicker's Hardness Number (VHN) determined per ASTM E384-99e1 being at least about 15.00, and a fracture toughness (KIC) per Evans and Charles being at least about 5.0 MPa·m1/2.