Young’s modulus and fatigue investigation of aluminum nitride films deposited on 304 stainless steel foils using micro-fabricated cantilevers

Zheng, Qiu; Minh, Le Van; Kuwano, Hiroki

doi:10.1016/j.sna.2018.11.022

Cited by 7 publications

(13 citation statements)

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“…The resonant fatigue testing system developed in a previous study (15) was used. This system can detect the amplitude of the vibrating specimen by using a laser displacement sensor (Keyence, LK-H050).…”

Section: Methodsmentioning

confidence: 99%

“…(15) After the SUS430 substrate was micromachined to from the cantilever shape by electrochemical etching [ Fig. 1(c)], (15,20) chromium (Cr) and gold (Au) films were deposited on a cantilever specimen for positioning when measuring the amplitude of the specimen during fatigue tests [ Fig. 1(d)].…”

Section: Fabrication Of Specimensmentioning

confidence: 99%

“…(9)(10)(11)(12)(13) Also, the fatigue behavior of materials with heterolayered structures is affected by the material-layer composition. (14,15) A previous study on the fatigue of 1-μm-thick AlN films deposited on both sides of a 50-μm-thick SUS304 foil showed that the fatigue limit of the materials in the AlN/ SUS304/AlN structure was higher than that of SUS304 foils. (15) Recently, metal foils with a low coefficient of thermal expansion (CTE) close to that of piezoelectric films have become more attractive for use as structural materials for micro-PVEHs.…”

Section: Introductionmentioning

confidence: 99%

“…(14,15) A previous study on the fatigue of 1-μm-thick AlN films deposited on both sides of a 50-μm-thick SUS304 foil showed that the fatigue limit of the materials in the AlN/ SUS304/AlN structure was higher than that of SUS304 foils. (15) Recently, metal foils with a low coefficient of thermal expansion (CTE) close to that of piezoelectric films have become more attractive for use as structural materials for micro-PVEHs. SUS430 foils with a lower CTE than SUS304 and whose manufacturing can be scaled up as easily as SUS304 are the focus of our interest.…”

Section: Introductionmentioning

confidence: 99%

“…Then fatigue tests of SUS430 foils and AlN/SUS430/ AlN heterolayered materials were subsequently conducted by using a resonant fatigue testing system. (15,17,18) The stress-number of cycle (S-N) curves, fatigue limit, and fatigue failure are discussed in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Fatigue Analysis of AlN/SUS430/AlN Heterolayered Foils in Micromachined Devices

Zheng¹,

Minh²,

Nguyen³

et al. 2020

Sensors and Materials

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The combination of piezoelectric aluminum nitride (AlN) films with flexible substrates made of stainless steel (SUS) foils has been applied in low-frequency and robust microdevices, especially in piezoelectric vibration energy harvesters (PVEHs). To find guides in the design of PVEHs, the fatigue properties of micromachined specimens fabricated using SUS430 foils and AlN/SUS430/AlN heterolayered foils were investigated in this work. In particular, the thickness dependence of AlN films on the fatigue behavior of AlN/SUS430/AlN heterolayered foils was investigated. AlN films with different thicknesses of 1 and 2 μm were deposited on 50-μm-thick SUS430 substrates. The specimens for fatigue tests were prepared as cantilevers by microfabrication processes. First, Young's moduli were measured. Fatigue tests were subsequently conducted by resonant bending. The fatigue behavior is discussed in this paper on the basis of both the stress-number of cycle (S-N) curves and the fatigue failures on the surfaces of the cantilevers. The fatigue limits of SUS430 (50 μm), AlN (1 μm)/ SUS430 (50 μm)/AlN (1 μm), and AlN (2 μm)/SUS430 (50 μm)/AlN (2 μm) were estimated to be 264, 291, and 368 MPa, respectively. The larger stiffness of the foils with a heterolayered AlN/SUS430/AlN structure indicated their larger fatigue limit than the SUS430 foil. Fatigue failure in the form of cracks was observed on the surface of SUS430 for AlN (1 μm)/SUS430/ AlN (1 μm) when vibrating at the maximum stress of 488 MPa for 2.9 × 10 7 cycles. Surface defects of intrusions and slip bands rather than cracks were observed on the SUS430 substrate for the heterolayered AlN (2 μm)/SUS430/AlN (2 μm) structure when vibrated at the maximum stress of 605 MPa for 2.9 × 10 7 cycles, resulting in its higher fatigue limit than that of AlN (1 μm)/SUS430/AlN (1 μm). No surface defects on AlN films were observed after undergoing the aforementioned long-cycle vibration.

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Section: Methodsmentioning

confidence: 99%