Space scientists have increased the strength of pure silver five times by blending into it a small percentage of tiny sapphire "whiskers." At the same time they settled a long-standing question of whether the "whisker" technique can be used to produce ultra-strength metal materials.
Dr. Willard H. Sutton, of General Electric's Missile and Space Vehicle Department in Philadelphia, said similar techniques applied to highstrength metals can be expected to produce materials several times stronger at white heat than any high-strength alloy.
The purpose of the work, being done at the Department's Space Sciences Laboratory under a contract from the Bureau of Naval Weapons, is to help overcome one of the problems in space vehicle and advanced aircraft design--the heat barrier. There is a lack of structural materials that will maintain strength at the high temperatures created by reentry, hypersonic air speeds, and powerful jet and rocket engines.
The theory behind "whisker" reinforcement is : Laboratory-grown whiskers, which consist of a single crystal of alumina (or sapphire), have shown extremely high strength--some can withstand tensions up to several million pounds per square inch. However, they have neither the rigidity nor the bulk to be machined or used as structural pieces or engine parts.
Currently known high-strength metals, including steels, can be machined into precision parts and are rigid, but