STP1111: The Relative Ignitability and Flammability of Lead-Tin Binary Alloys in Oxygen

    Sircar, S
    Principal ScientistMechanical EngineerAerospace Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test Facility, Las Cruces, New Mexico

    Stoltzfus, JM
    Principal ScientistMechanical EngineerAerospace Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test Facility, Las Cruces, New Mexico

    Gunaji, MV
    Principal ScientistMechanical EngineerAerospace Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test Facility, Las Cruces, New Mexico

    Pages: 10    Published: Jan 1991


    Abstract

    The relative ignitability and flammability of pure lead (Pb), pure tin (Sn), and a series of binary Pb-Sn alloys in liquid and gaseous oxygen was studied. Resistance to ignition by mechanical impact in liquid oxygen was studied using the Standard Test Method for Compatibility of Materials with Liquid Oxygen (the ASTM D-2512 technique) with slight modifications. Flammability was studied using the NASA White Sands Test Facility's (WSTF) promoted combustion tester. There were no reactions in the mechanical impact test for pure Pb, pure Sn, Pb-98.5Sn, Pb-10Sn, Pb-5Sn, and Pb-2Sn. However, the other alloys exhibited between two and six reactions out of twenty impacts. In the promoted combustion test, the threshold oxygen pressure required for complete consumption of a pure Pb sample was about 5 MPa (700 psig), whereas, for all the binary alloys tested and for pure Sn, the value was about 2 MPa (300 psig). The results obtained from the tests have been correlated with the Pb-Sn equilibrium binary phase diagram, the thermophysical properties of Pb-Sn binary alloys, and the thermodynamic properties of the oxides of both Pb and Sn. The chemical segregation characteristics of Pb and Sn in the presence of pure oxygen at high temperatures have been used to explain the results of the promoted combustion tests.

    Keywords:

    Lead-tin alloys, oxygen, flammability, ignitability, lead, mechanical impact, promoted combustion, tin, solders, safety


    Paper ID: STP17767S

    Committee/Subcommittee: G04.01

    DOI: 10.1520/STP17767S


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