Ryujiro Udo

Cross comparison of thin-film tensile-testing methods examined using single-crystal silicon, polysilicon, nickel, and titanium films

This paper reports on the results of comparing different types of tensile testing methods that are used to evaluate thin-film properties. We tested the same material fabricated on a single wafer using different testing techniques at five different research institutions. The testing methods were different in the way the specimen was gripped. Materials tested were single-crystal silicon (SCS), polysilicon, nickel, and titanium films. Specimens with three different shapes were processed through the same fabrication steps. The tensile strength, fracture strain, and Youngs modulus of the films were measured and compared. The measured values of the mechanical properties of all the testing methods were in good agreement with each other, thus demonstrating their accuracy.

Cross comparison of thin film tensile-testing methods examined with single-crystal silicon, polysilicon, nickel, and titanium films

This paper reports on the results of comparing different types of tensile testing methods that are used to evaluate thin-film properties. We tested the same material fabricated on a single wafer using different testing techniques at five different research institutions. The testing methods were different in the way the specimen was gripped. Materials tested were single-crystal silicon (SCS), polysilicon, nickel, and titanium films. Specimens with three different shapes were processed through the same fabrication steps. The tensile strength, fracture strain, and Youngs modulus of the films were measured and compared. The measured values of the mechanical properties of all the testing methods were in good agreement with each other, thus demonstrating their accuracy.This paper reports the results of a comparison of the different types of tensile testing methods used to evaluate thin films properties. We tested the same material fabricated on a single wafer using different testing techniques at five different research institutions. The testing methods are different in the way of gripping the specimen. Materials tested were single-crystal silicon, polysilicon, nickel, and titanium films. Specimens of three different shapes were processed through the same fabrication steps. The tensile strength, fracture strain, and Youngs modulus of the films were measured and compared. The measured values of the mechanical properties were in good agreement with each other among the testing methods, thus demonstrating the accuracy of these testing methods.

Prediction of Cavitation Intensity in Pumps Based on Propagation Analysis of Bubble Collapse Pressure Using Multi-Point Vibration Acceleration Method

We developed a `multi-point vibration acceleration method` for accurately predicting the cavitation intensity in pumps. Pressure wave generated by cavitation bubble collapse propagates and causes pump vibration. We measured vibration accelerations at several points on a casing, suction and discharge pipes of centrifugal and mixed-flow pumps. The measured vibration accelerations scattered because the pressure wave damped differently between the bubble collapse location and each sensor. In a conventional method, experimental constants are proposed without evaluating pressure propagation paths, then, the scattered vibration accelerations cause the inaccurate cavitation intensity. In our method, we formulated damping rate, transmittance of the pressure wave, and energy conversion from the pressure wave to the vibration along assumed pressure propagation paths. In the formulation, we theoretically defined a `pressure propagation coefficient,` which is a correlation coefficient between the vibration acceleration and the bubble collapse pressure. With the pressure propagation coefficient, we can predict the cavitation intensity without experimental constants as proposed in a conventional method. The prediction accuracy of cavitation intensity is improved based on a statistical analysis of the multi-point vibration accelerations. The predicted cavitation intensity was verified with the plastic deformation rate of an aluminum sheet in the cavitation erosion area of the impeller blade. The cavitation intensities were proportional to the measured plastic deformation rates for three kinds of pumps. This suggests that our method is effective for estimating the cavitation intensity in pumps. We can make a cavitation intensity map by conducting this method and varying the flow rate and the net positive suction head (NPSH). The map is useful for avoiding the operating conditions having high risk of cavitation erosion.