Piezoelectric thin films on high acoustic velocity non piezoelectric substrates, such as ZnO and AlN, deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films were epitaxialy grown on R-Al 2 O 3 and C-Al 2 O 3
Measurement of residual stresses in Al2O3/Ni laminated composites using an X-ray diffraction technique
β Scribed by L. Hehn; C. Zheng; J. J. Mecholsky; C. R. Hubbard
- Publisher
- Springer
- Year
- 1995
- Tongue
- English
- Weight
- 569 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0022-2461
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β¦ Synopsis
Using an X-ray diffraction technique, macro-residual stresses were measured in laminated composites consisting of alternating layers of ~-AI203 and nickel. The in-plane thermal mismatch stresses which develop during fabrication were found to be compressive and tensile in the ~-AI203 and nickel layers, respectively. The magnitude of the in-plane stresses was found to be ~ 110 MPa. Models of laminate structures predict the stress state to be biaxial in the plane of the layers. However, substantial stresses were observed perpendicular to the plane of the laminate; this stress might be due to the hot-pressing procedure used to fabricate the samples. The stress on the side surface of a laminate was measured using the indentation method and the results were consistent with those obtained by the X-ray method. Three samples were heated to 700, 900 and 1000 ~ respectively, and then cooled to test the effect of stress relaxation of the residual stresses due to the thermal expansion. The heat treatments (700-1000 ~ had no effect on the measured stress states of the laminates.
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The residual stresses in YAG phase in directionally solidified eutectic (DSE) Al 2 O 3 /Y 3 Al 5 O 12 (YAG) ceramic composite were estimated by X-ray diffraction technique. The YAG skeleton specimen without Al 2 O 3 phase, extracted from the composite, was used as a thermally-induced stress-free ref
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