DEVELOPMENT OF A CRACK GAUGE BY USING ION-BEAM MIXING

The ion beam mixing technique has been applied to develop a crack gaug e. This gauge consists of an array of insulator/conductor bands on an insulating substrate which is attached to the test piece. The principl e of a gauge is based on the measurement of resistance change brought by cutting of conductive bands due to crack growth in the test piece. An array of insulator/conductor sets was formed by ion bombardment on a thin conductor layer which had been evaporated onto the insulator su bstrate. For the insulator substrate, SiO2 was used, and Ru was the co nductor. An array pattern was produced with a mask by separating the i on beam. To confirm our idea, a crack gauge of 8 x 8 mm was fabricated on a compact tension test piece of stainless steel. The spacing of th e conductive bands of 0.1 mm width was 0.1 mm. To measure the resistiv ity, thin multilayers of Si(5 nm)/Ru(50 nm)/Si(30 nm)/SiO2(300 nm) fil ms were mixed by 300 keV Xe+ ions. The resistivity of the mixing regio n was found to change drastically at the dose of 7 x 10(16) Xe+/cm2. W hen the test piece cracked under tension, the gauge measured the crack length with good accuracy.