BEHAVIOR STUDY OF SAPPHIRE WOOL ALUMINUM AND ALUMINUM ALLOY COMPOSITES

The program was concerned with (a) the improvement of methods for fabricating Al/Al2O3 and Al-alloy/Al2O3 composites, (b) the determination of their properties as a function of volume fraction and temperature, and (c) the interpretation of the test results in terms of existing theories of composite behavior. The results of this program over the past contract year are summarized as follows: (1) The maximum composite tensile strength attained at 500C was 67,800 psi, representing a strength to density ratio of 6.77 x 100,000 in. At the same temperature, the maximum 100-hour rupture life was 18,000 psi. It was found that the static tensile modulus was the same as the dynamic bending modulus. The damping characteristics of Al/Al2O3 composites showed no correlation with tensile strength. A total of 110 specimens were fabricated during this period. (2) Automatic methods were developed to beneficiate, to classify, and to obtain semi-orientation in alumina wool tapes. These tapes were used to fabricate composite specimen. (3) Square specimens 1/8 inch x 1/8 inch x 2.0 inches were successfully fabricated and tested. The fiber distribution around the edges was good. (4) The fatigue strength of Al/Al2O3 composites at room temperature was not a strong function of the number of cycles. (Author)