Tribology Measurement by Thin Layer Activation Method Using Proton Beam

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A method of measuring iron wear using thin layer activation is discussed. The iron surface is activated by a ^<56>Fe(p, n)^<56>Co reaction etc., using a 7.00 MeV protom beam from a tandem Van de Graff accelerator. Irradiation of 0.5-1 muA bean currents produces 1-10 muCi of ^<56>Co activities in a layer about 50 mum thick. To get the basic Depth profile of cobalt activities, a 1.5 cm iron cube with a 3 mm diameter activation area is used to produce a wear calibration curve. Wear is produced by a polishing machine and wear thickness is measured by a precise electric micrometer. Monitoring radiation instruments are a 3 in. diameter X 3 in. NaI (Tl) scintillator and a high-purity Ge detector. A detailed iron wear calibration curve using ^<56>Co, ^<57>Co and ^<58>Co activities is obtained in accordance with iron wear thickness.Thin layer activation technique was applied to the on-line iron wear measurement of engine cam nose. The wearing amount of this activated part was measured using Ge semiconductor detector by on-line and nondestructive method. For the application of this method to the real car engine part (engine cam nose), the data acquisition system using microcomputers was built. The wear characteristics were successfully measured and an effectiveness of this method was verified.