A separate-target sputtering process has been applied to fabrication of TiNi shape memory alloy (SMA) for microelectromechanical systems (MEMS). This process employs separate Ti and Ni sputtering targets and independently controllable RF power source for each target. Since RF power ratio can change the composition of the films as required, the shape memory properties can be better controlled. This process would enable efficient batch production of MEMS devices and components similarly to the LSI batch process. This process is expected to be a more appropriate method for mass production than other techniques such as machining from bulk SMA sheets or wires and deposition of SMA films from a single TiNi alloy target. The TiNi SMA films in the present study were fabricated by co-sputtering from two separate targets and vacuum-annealing for crystallization. The phase transformation behavior of the crystallized films was observed by differential scanning calorimetry (DSC) and x-ray diffractometry (XRD). DSC showed exothermic/endothermic peaks corresponding to phase transformations: martensitic transformation around at 345 K and reverse martensitic transformation around at 365 K. The transformations of crystal structure were also examined by temperature-controlled XRD analysis. The formed films were confirmed to show shape memory effect (SME) by these results.
In the beginning stage of MITI micromachine project, the committee on the standardization established in Micromachine Center recognized the importance of measurement technique for the promotion and the systemization of the micromachine technology. Micromachine Center is the organizing body for private sectors working in the MITI micromachine project which started in 1991. MITI stands for Ministry of International Trade and Industry in Japan. In order to known the requirements on the measurement technologies, the questionnaire was organized by the measurement working group in the committee. This talk covers the questionnaire and its results, and some research results obtained at National Research Laboratory of Metrology working as a member in the project.
The mass production of silicon accelerometers has clarified that the current acceleration standard is not perfect. The acceleration standard is usually transferred by a reference accelerometer with the so-called back-to-back connection technique. Manufacturers, however do not explain what sort of calibration technique is applied to the reference accelerometer in the impact acceleration range. This paper proposes a novel impact technique for accelerometers calibration. The input acceleration to an accelerometer to be tested is generated by the reflection of an elastic pulse at one end surface of a bar. The bar is called Davies Bar, after Prof. Davies, who measured the dynamic displacement of the end surface of a metal bar by electrodes. The experiment was the comparison between the calibration of RION PV-44A accelerometer by ENDEVCO 2270 and that by NRLM method. The paper concludes that Davies' Bar should be used as the reference for the impact acceleration, ranging from roughly 200 [m/s2] to 1000,000 [m/s2] for mainly following reasons: (1) NRLM method is based on laser interferometer measurement with the reliable accuracy. (2) The frequency bandwidth of the impact acceleration generated using Davies bar is much wider than that of reference accelerometers. (3) Back to back connection does not always enable the comparison between the measurement of the connecting surface motion and the accelerometers' outputs.
This paper proposes the new technique for the frequency response characterization of the laser vibrometry or the laser displacementmetry, where the optical interference is the working principle. In order to investigate the frequency response of laser vibrometers or laser displacement meters, the surface of high speed translational motion with the broad frequency bandwidth is absolutely required. That motion is materialized by the reflection of an elastic pulse propagating in a metal bar. A projectile made of aluminum is accelerated by the pressurized air and impinges on one end surface of the bar. The elastic wave is generated by the collision and propagates in the bar axis direction and reflects at the other end surface of the bar. The bar is supported by four steel bearing balls which are placed on the V-shaped grooves. The motion of the end surface can be considered to be in plain based on the numerical calculation. The surface is measured simultaneously using the reference laser interferometer developed in NRLM and a laser displacement meter based on the heterodyne technique (Hoshin Electronics HS-1100). HS-1100 uses the real time fringe counting technique. The reference interferometer, on the other hand uses a transient recorder (Tektronix RTD-710) which stores all of the interference signals during the elastic pulse reflection. The analysis and the wave form calculation based on the phase analysis is done after the experiment, leading to the broad frequency bandwidth. The comparison in the frequency domain using Fast Fourier Transform provides the frequency response characteristics of the tested laser displacement meter. It turned out that bandwidth of HS-1100 was up to 20 kHz, though the design value was 100 kHz.
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