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TiH 2 powder is added as a reactant and pore-forming agent to produce porous NiTi shape-memory alloys (SMAs). The transformation behavior of porous NiTi alloys is investigated because it is relevant to the engineering and medical applications of SMAs. It is found that the transformation behavior of porous NiTi alloys is different from that of cast NiTi alloys. It is demonstrated for the first time, by in situ X-ray diffraction (XRD), that there is no R-phase transformation in porous NiTi alloys, and a broadened, two-peak phenomenon observed with a differential scanning calorimeter (DSC) is not associated with R-phase transformation. The characteristic transformation temperatures of porous NiTi alloys are independent of sintering temperature, sintering time, TiH 2 content, and the heating/cooling rate during thermal cycling between ϩ123 and ϩ423 K. Further, the latent heats of transformation are associated with the TiH 2 content and the sintering conditions.

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A water hydraulic throttle valve is often used to control the water flow in piping systems. When the water flows through the valve port, cavitation occurs frequently because of the high pressure drop across the valve. The cavitation can lead to wear, vibration and noise. To solve the problem, a modified throttle valve with a drainage device is proposed to suppress the cavitation. A contrasting test was conducted to analyze the effect of drainage device on the cavitation suppression. For evaluating the influence of inlet pressure and outlet pressure on the ability of the drainage device to suppress cavitation, the power spectrum density (PSD), normalized intensity, and cavitation suppression coefficient (CSC) of dynamic pressure are introduced. The results indicate that adopting the drainage device is a feasible method to suppress cavitation. In addition, the inlet pressure and outlet pressure have a great influence on the capacity for cavitation suppression of the drainage device (CCSDD) by changing the intensity of cavitation. When the inlet pressure is at 4.0 MPa, the cavitation is generated and the CCSDD is weak. With increasing inlet pressure, the intensity of cavitation and CCSDD is gradually enhanced. But when the inlet pressure increases to 7.0 MPa, the cavitation is saturated and the cavitation suppression by the drainage device begins to decrease. On the other hand, the effect of cavitation suppression decreases significantly when the outlet pressure increases from 1.4 MPa to 3.8 MPa.

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