BUREAU OF STANDARDS NOTES. [J. F. I. military demands for these metals are considerable. These facts were responsible for the sponsoring by the War Department of recent studies at the bureau aimed towards the reduction or possible elimination of the amounts of tin and antimony needed for bearings.
One phase of this work was a study of the wear resistance and other mechanical properties of ten white-metal bearing alloys. The alloys tested included two tin-base and seven lead-base alloys and one alloy of cadmium and zinc.
Each of the properties, with the exception of wear, was determined at several temperatures ranging from 2o ยฐ to 200 ยฐ C. (68ยฐ-39 oยฐ F.), since it is in reality the properties at the higher temperatures that play the major part in determining the success or failure of a bearing metal under service conditions. Resistance to wear was determined only at 20 ยฐ C. No one of the alloys considered was found to excell in all of the mechanical properties studied. Thus, the tin-base alloys showed higher resistance to wear and in most cases had higher Izod impact values, at each temperature of test, than the lead-base alloys, but in most cases, showed lower resistance to pounding than the lead-base and cadmium-zinc alloys. The hardness numbers and compressive properties of the tinbase alloys were found to be lower than those for the alkalinemetal hardened lead and the cadmium-zinc alloys. The alkaline metals used for hardening lead were calcium and barium. The mechanical properties of the lead-antimonytin alloys, in most cases, were higher as the tin content was increased.
Crankshaft bearings of four compositions were prepared for service tests in U. S. Army Class B. trucks. These compositions consisted of two tin-base and two lead-base alloys. The results of these tests indicated that the tin-base alloys were superior in their wear resistance to the lead-base alloys. These results were consistent with those obtained on wear in the laboratory tests. FACTORS AFFECTING THE PHYSICAL PROPERTIES OF CAST RED BRASS.