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Prepn of shape memory alloy film with very small heat stagnation

A memory alloy and thin film technology, applied in the field of micromachining, can solve problems such as multiple heating and cooling times, limit driving frequency, etc., and achieve the effect of solving low response frequency, improving dynamic characteristics, and broadening the scope of application.

Inactive Publication Date: 2003-02-26
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This means that more heating and cooling time is required to overcome the thermal hysteresis during the phase transition, thus limiting the increase in driving frequency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] Using a glass substrate, the background vacuum before sputtering: 8×10 -5 pa; sputtering argon working pressure: 0.8Pa; sputtering power: 250W; sputtering time: 100 minutes; crystallization temperature: 500°C, time: 30 minutes. The weight percentages of the film components obtained by deposition are: Ni: 52.6%, Ti: 47.4%, and the film thickness is 5 microns. After the film is peeled off from the substrate, it is soft and deformable with good mechanical properties. The resistance-temperature test curve shows that the phase transition process above room temperature is R phase transition and reverse phase transition, that is, austenite phase transition, which has complete phase transition characteristics. The average temperature of the R phase transition is 58°C, and the thermal hysteresis width of the phase transition is almost 0°C. X-ray diffraction analysis results show that the film structure is R phase and a small amount of Ti at room temperature 2 Ni precipitated ...

Embodiment 2

[0013] Ni: 51.9%, Ti: 48.1%, and a film thickness of 8 micrometers. A thin film is deposited on the deformable region on top of the silicon cavity of the micropump, which serves as the driver of the micropump. The sputtering conditions are: background vacuum: 6×10 -5 pa; argon working pressure: 0.4Pa; sputtering power: 200W; sputtering time: 110 minutes; crystallization temperature: 530°C, the time is about 30 minutes.

[0014] The thickness of the film deposited by the above sputtering parameters is about 5 microns, and the R phase transition is above room temperature. After the film is stripped by resistance, it is heated by applying a pulse current of a certain frequency to produce a periodic phase change. The displacement changes of NiTi / Si thin films with R phase transition and martensitic phase transition were measured by optical interferometric micro-displacement measuring instrument. When the frequency is less than 20 Hz, the displacement of the driven membrane with...

Embodiment 3

[0016] Ni: 52.25%, Ti: 47.75%, the film thickness is 6.5 microns. The thin film is deposited on the deformable area on the top of the silicon chamber of the micropump as the driver of the micropump. The sputtering conditions are: background vacuum: 4×10 -5 pa; argon working pressure: 0.1Pa; sputtering power: 150W; sputtering time: 120 minutes; crystallization temperature: 550°C, the time is about 20 minutes.

[0017] The shape memory alloy / silicon drive film with R-phase characteristics was deposited under the above conditions, and assembled into a micropump. Under the condition of the same driving area and shape, compare the working conditions of R phase transformation and martensitic transformation. The characteristic frequency of the R phase change micropump under water load can reach 167Hz (the flow rate is 7um / min), and the characteristic frequency is 6 times that of the martensitic phase transformation. In addition, the advantages of high reliability and long working l...

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Abstract

The present invention invention belongs to the field of film material and film technology. The invented very small thermo-lag shape memory alloy film consists of two-element NiTi alloy with Ni 51.9-52.6 wt% and Ti 47.4-48.1 wt% and has a thickness of 5-8 microns. It is prepared through magnetically controlled sputtering and post-crystallizing process including the step of: selecting cast NiTi alloy as sputtering target; sputtering NiTi film and post-crystallizing treatment of the NiTi film. The present invention has typical R phase change characteristic at room temperature, and can take complete R phase change and inverse phase change. NiTi / Si driving film has characteristic frequency up to 400 Hz and obvious raised dynamic characteristic. The present invention raises the response frequency of the shape memory alloy.

Description

technical field [0001] The invention relates to a method for preparing a shape memory alloy film, in particular to a method for preparing a shape memory alloy film with extremely small thermal hysteresis, and belongs to the technical field of micromachining. Background technique [0002] Shape memory alloys are widely used as temperature and force detection and control elements due to their unique mechanical properties. Its application fields involve industrial control, electronic technology, medical and health care, aerospace, military defense and many other fields. NiTi shape memory alloy is one of the most widely used shape memory alloy materials. After decades of research and accumulation, the application technology of its bulk material forms such as block, plate, thin strip and silk has been very mature. Since the 1980s, with the rapid development of micro-electromechanical system technology, the research on micro-actuators, an important and key component in this tech...

Claims

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Application Information

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IPC IPC(8): C22C19/03C23C14/14C23C14/34
Inventor 徐东程秀兰蔡炳初王莉
Owner SHANGHAI JIAO TONG UNIV
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