Stress-rupture resistant sintered silicon nitride
AssigneeAlliedSignal Inc.
InventorChien-Wei Li
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Abstract
A silicon nitride sintered body has a composition consisting essentially of from 75 to 96 wt % of silicon nitride; yttrium oxide present in an amount ranging from about 2 to 10 wt %; at least one oxide of the Lanthanide (Ln) element, wherein the molar ratio of Ln to Y is smaller than 1; strontium oxide present in an amount wherein the molar ratio of Sr to the sum of Y and Ln is between 0.1 and 0.5; and 0.2 to 5 wt % of silicon carbide. Such a ceramic has high strength, high toughness and long term durability, and is especially suited for industrial applications such as components for gas turbine and automotive engines.
Claims10
A silicon nitride sintered body having a composition consisting essentially of
- (a) about 75% to 96 wt % silicon nitride;
- (b) about 2-10 wt % yttrium oxide;
- (c) at least one oxide of Lanthanide (Ln) present in an amount wherein the molar ratio of Ln to Y is smaller than 1;
- (d) strontium oxide present in an amount wherein the molar ratio of Sr to the sum of Y and Ln is between 0.1-0.5;
- and
- (e) about 0.2 to 5 wt % of silicon carbide.
A silicon nitride sintered body having a composition consisting essentially of
- (a) about 85 to 96 wt % of silicon nitride;
- (b) about 3-7 wt % yttrium oxide;
- (c) at least one oxide of Lanthanide (Ln) present in an amount wherein the molar ratio of Ln to Y is smaller than 1;
- (d) strontium oxide present in an amount wherein the molar ratio of Sr to the sum of Y and Ln is between 0.17-0.25;
- and
- (e) about 0.2 to 5 wt % of silicon carbide.
Dependencies are inferred from the claim text.