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Non-destructive evaluation of ceramics by scanning acoustic microscopy
optical microscope. These make it possible to measure range to a thousandth of a wavelength. Other techniques involving scanning optical microscopy have been demonstrated which make it possible to carry out profiling of semiconductor circuits. Developments of these methods are now being actively pursued for use in the semiconductor industry. Developments of acoustic technology pioneered on this program have proved extremely important for measuring internal defects in composites and surface cracks on ceramics. 41219
Roth, D.J.
Flaw characterization in structural ceramics using scanning laser acoustic microscopy National Aeronautics and Space Administration, Cleveland, Ohio (United States) Lewis Research Centre, N88-22415/9/GAR 16 pp. (May 1988) The ability of scanning laser acoustic microscopy (SLAM) to characterize artificially seeded voids in sintered silicon nitride structural ceramic specimens was investigated. The voids ranged from 20 to 430 microns in diameter and were embedded up to 2 mm beneath the surface of the specimens. Probability of detection was determined as a function of void depth and size. Trigonometric relationships and Airy's diffraction theory were used to obtain predictions of void depth and size from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain because of measurement uncertainty and the limitations of the 100 MHz SLAM applied to typical ceramic specimens. 41206
Som, A.K.; Bond, L.J.
microscopy (SAM), scanning laser acoustic microscopy (SLAM), and thermoacoustic microscopy (TAM). These techniques are evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture (MOR) bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described, with the emphasis being on statistics of detectability of flaws that constitute potential fracture origins. Further, it is shown that radiographic evaluation and guidance helped develop uniform high-density Si3N4 MOR bars with improved four-point flexural strength (875,544, and 462 MPa at room temperature, 1200 deg C, 1370 C, respectively) and reduced scatter in bend strength. 40959
Dussoulier, A.
Optimal non-destructive defect inspection of airplane turbine ceramic parts (In French) Direction des Recherches, Et ude s et Techniques, Paris (France). Centre de D o c u m e n t a t i o n de L ' A r m e m e n t , PB88-205158/GAR, PCE04/MF E04, 64 pp. (Dec. 1987) The report sums up previous research on non-destructive defect inspection techniques applied to thermomechanical ceramics and gives the latest developments on those methods selected as most sensitive and most easily adapted for industrial use. Results are discussed for five major techniques: conventional x-ray photography, micro-focus x-ray photography, immersion ultrasound, fluorescent penetration studies, and acoustic microscopy. Combined use of fluorescent dye studies and acoustic microscopy gives the best results for detection of surface flaws (cracks). X-ray photography and immersion ultrasound techniques complement each other perfectly for detection of internal defects (cavities or inclusions).
Scruby, C.B.
High frequency ultrasonic inspection
40809
Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1661-1666. E d i t e d by J. Boogaard and G.M. van Dijk, Elsevier, 1989. A high frequency digital ultrasonic system has been developed for acoustic imaging and material characterisation. The system functions in a pulse-echo configuration in the frequency range 25 MHz to 100 MHz, at a frequency depending on transducer selection. It can be used as an acoustic microscope and employ compression waves to give high resolution C-scans. Addition imaging techniques, which employ leaky Rayleigh waves, are being investigated together with the supporting theory. Digital capture capability for the 'RF' (radiofrequency) signal received at selected points is included. The application of various signal processing techniques is being considered together with the use of inversion algorithms which can combine to give a complete characterisation of the material. Examples of images, RF output and spectra are provided.
Acoustic microscopy
41202
Morsch, A.; Arnold, W.
Holographic reconstruction by backpropagation of defect images obtained by scanning laser acoustic microscopy Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1617-1619. E d i t e d by J. Boogaard and G.M. van Dijk, Elsevier, 1989. Scanning Laser Acoustic Microscope (SLAM) images which are acoustic holograms can be improved by backpropagation in the Fourier domain of the displacement field measured at the surface of the sample. This technique is applied to delineate the size of defects in advanced ceramics.
U K A E A Underlying Research Programme A n n u a l Rep o r t, A p r il 1987 - M a r c h 1988, C ha pt e r 10.4.3, p. 124 (Nov. 1988) Two areas of improvement in acoustic microscopy work being undertaken at UKAEA, Harwell are described. Improvements in the electronic drive, amplification and analysis units mean very thin layers and small defects can be studied. The second area is the characterization of ceramics and composites. Cracks in engineering ceramics are being studied. The microscope also reveals the large elastic mismatch between matrix and fibres, in ceramic and metal composites. Buried fibres may also be imaged with the device.
Stelwagen, U.; Ramaekers, P.P.J.; van't Veen, P.P.; van der Wal, L. F.
40798
Non-destructive evaluation of ceramics by scanning acoustic microscopy Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands) 23-28 Apr. 1989, Vol. 1, pp. 747-752. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989 The principles, possibilities and limitations of low frequency, (10 to 100 MHz) scanning acoustic microscopy for NDE of technical ceramics are discussed. Volume flaws of 130 micro meters diameter at a depth of 500 micro meters in AI203 are detected and imaged. Surface breaking cracks of 10 to 15 micro meters width as well as a delamination in a 400 micro meters ZrO2-coating are imaged. 40728
41195
Hoffmann, B.; Arnold, W.
Photoacoustie microscopy of ceramic bending specimens Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1573-1578. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. A Photoacoustic Microscope was used to investigate surface and subsurface areas of ceramic bending specimens with artificial flaws. After this the samples were broken in a four-point-bending test. The comparison of the results of the fracture specification and the results of the nondestructive evaluation shows that a large fraction of the flaws causing the fractures were detected. An explanation is attempted for why the other part of the flaws causing the fractures could not be detected, and a quantitative evaluation of the detection probability is given for defects using photoacoustic phase images. 41167
Anon.
Nondestructive testing of ceramics. January 1970-September 1988 (Citations from the NTIS Database) National Technical Information Service, Springfield, Virginia (United States) PB88-868260/GAR, 177 pp. (Sep. 1988) This bibliography contains citations concerning the nondestructive techniques for testing or examining ceramic materials and ceramic bodies for the detection of flaws or defects. Applications for testing ceramic gas turbine engine materials, high performance structural ceramic materials, and the use of scanning laser acoustic microscopy (SLAM) are presented. 41163
Baaklini, G. Y.; Slima, S.J.; Sanders, W.A.
Nondestructive evaluation of sintered ceramics National Aeronautics and Space Administration, Cleveland, Ohio (United States) Lewis Research Centre, N88-22416/7/GAR 11 pp. (May 1988) Radiography and several acoustic and thermoacoustic microscopy techniques are investigated for application to structural ceramics for advanced heat engines. A coniparison is made of the results obtained from the use of scanning acoustic
40
Olympus Kogaku Kogyo Kabushiki Kaisha
Acoustic lens for use in acoustic microscope British Patent No. GB2192281 (6 Jun. 1988) An acoustic lens, for use in an acoustic microscope, comprises a solid state medium for propagating an acoustic wave having a wavelength lambdaA and having opposed end surfaces, an electric-acoustic transducer applied on one end surface of the solid state medium and having a radius a, and a spherical lens portion formed in the other end surface of the solid state medium and having an aperture of a radius w. The length 1 and the aperture radius w is normalized by the transducer radius a such that Z = llambda/a 2 and W = w/a. Values of Z and W are selected from such a region in a first quadrant of a Z-W coordinate system that desired power and/or phase are obtained, except for a known region neighbouring a point Z= 1 and W= 1. 40727
Busse, G.
Characterisation through thermal waves: applications of optoaconstic and phototherrnal methods Ultrasonic Methods in Evaluation of I n h o m o g e n e o u s Materials, Proceedings, Erice, (Italy), 15-25 Oct. 1985, pp. 105-119. E d ited by A. Alippi and W.G. Mayer. N A T O A d v a n c e d Study Institute Series E A ppl i e d Sciences, Vol. 126, Martinus Nijhoff, 1987 This paper considers the use of thermal waves for non destructive testing, through optoacoustic or photothermal methods. The generation and detection of thermal waves is described as well as their physical characteristics. Scanned thermal wave inspection, or imaging is discussed and applications suggested.
Ashurov, A.M.; Madvaliev, U.; Proklov, V. V.; Beremzhanov, I.M.; Zhavoronkov, A.A.
40716
Photoacoustic microscope with optical scanning Instruments and E x p e r i m e n t a l Techniques, Vol. 31, No. 2, Pt. 2, pp. 439-442 (Oct. 1988) A scanning photoacoustic microscope with a unit for control of twodimensional optical scanning and formation of a photoacoustic image is presented. The control circuit and photoacoustic cell are described. The
NDT International February 1990
Roth, D.J.
Flaw characterization in structural ceramics using scanning laser acoustic microscopy National Aeronautics and Space Administration, Cleveland, Ohio (United States) Lewis Research Centre, N88-22415/9/GAR 16 pp. (May 1988) The ability of scanning laser acoustic microscopy (SLAM) to characterize artificially seeded voids in sintered silicon nitride structural ceramic specimens was investigated. The voids ranged from 20 to 430 microns in diameter and were embedded up to 2 mm beneath the surface of the specimens. Probability of detection was determined as a function of void depth and size. Trigonometric relationships and Airy's diffraction theory were used to obtain predictions of void depth and size from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain because of measurement uncertainty and the limitations of the 100 MHz SLAM applied to typical ceramic specimens. 41206
Som, A.K.; Bond, L.J.
microscopy (SAM), scanning laser acoustic microscopy (SLAM), and thermoacoustic microscopy (TAM). These techniques are evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture (MOR) bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described, with the emphasis being on statistics of detectability of flaws that constitute potential fracture origins. Further, it is shown that radiographic evaluation and guidance helped develop uniform high-density Si3N4 MOR bars with improved four-point flexural strength (875,544, and 462 MPa at room temperature, 1200 deg C, 1370 C, respectively) and reduced scatter in bend strength. 40959
Dussoulier, A.
Optimal non-destructive defect inspection of airplane turbine ceramic parts (In French) Direction des Recherches, Et ude s et Techniques, Paris (France). Centre de D o c u m e n t a t i o n de L ' A r m e m e n t , PB88-205158/GAR, PCE04/MF E04, 64 pp. (Dec. 1987) The report sums up previous research on non-destructive defect inspection techniques applied to thermomechanical ceramics and gives the latest developments on those methods selected as most sensitive and most easily adapted for industrial use. Results are discussed for five major techniques: conventional x-ray photography, micro-focus x-ray photography, immersion ultrasound, fluorescent penetration studies, and acoustic microscopy. Combined use of fluorescent dye studies and acoustic microscopy gives the best results for detection of surface flaws (cracks). X-ray photography and immersion ultrasound techniques complement each other perfectly for detection of internal defects (cavities or inclusions).
Scruby, C.B.
High frequency ultrasonic inspection
40809
Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1661-1666. E d i t e d by J. Boogaard and G.M. van Dijk, Elsevier, 1989. A high frequency digital ultrasonic system has been developed for acoustic imaging and material characterisation. The system functions in a pulse-echo configuration in the frequency range 25 MHz to 100 MHz, at a frequency depending on transducer selection. It can be used as an acoustic microscope and employ compression waves to give high resolution C-scans. Addition imaging techniques, which employ leaky Rayleigh waves, are being investigated together with the supporting theory. Digital capture capability for the 'RF' (radiofrequency) signal received at selected points is included. The application of various signal processing techniques is being considered together with the use of inversion algorithms which can combine to give a complete characterisation of the material. Examples of images, RF output and spectra are provided.
Acoustic microscopy
41202
Morsch, A.; Arnold, W.
Holographic reconstruction by backpropagation of defect images obtained by scanning laser acoustic microscopy Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1617-1619. E d i t e d by J. Boogaard and G.M. van Dijk, Elsevier, 1989. Scanning Laser Acoustic Microscope (SLAM) images which are acoustic holograms can be improved by backpropagation in the Fourier domain of the displacement field measured at the surface of the sample. This technique is applied to delineate the size of defects in advanced ceramics.
U K A E A Underlying Research Programme A n n u a l Rep o r t, A p r il 1987 - M a r c h 1988, C ha pt e r 10.4.3, p. 124 (Nov. 1988) Two areas of improvement in acoustic microscopy work being undertaken at UKAEA, Harwell are described. Improvements in the electronic drive, amplification and analysis units mean very thin layers and small defects can be studied. The second area is the characterization of ceramics and composites. Cracks in engineering ceramics are being studied. The microscope also reveals the large elastic mismatch between matrix and fibres, in ceramic and metal composites. Buried fibres may also be imaged with the device.
Stelwagen, U.; Ramaekers, P.P.J.; van't Veen, P.P.; van der Wal, L. F.
40798
Non-destructive evaluation of ceramics by scanning acoustic microscopy Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands) 23-28 Apr. 1989, Vol. 1, pp. 747-752. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989 The principles, possibilities and limitations of low frequency, (10 to 100 MHz) scanning acoustic microscopy for NDE of technical ceramics are discussed. Volume flaws of 130 micro meters diameter at a depth of 500 micro meters in AI203 are detected and imaged. Surface breaking cracks of 10 to 15 micro meters width as well as a delamination in a 400 micro meters ZrO2-coating are imaged. 40728
41195
Hoffmann, B.; Arnold, W.
Photoacoustie microscopy of ceramic bending specimens Proceedings of the 12th World Conference on Non-Destructive Testing, A m s t e r d a m (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1573-1578. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. A Photoacoustic Microscope was used to investigate surface and subsurface areas of ceramic bending specimens with artificial flaws. After this the samples were broken in a four-point-bending test. The comparison of the results of the fracture specification and the results of the nondestructive evaluation shows that a large fraction of the flaws causing the fractures were detected. An explanation is attempted for why the other part of the flaws causing the fractures could not be detected, and a quantitative evaluation of the detection probability is given for defects using photoacoustic phase images. 41167
Anon.
Nondestructive testing of ceramics. January 1970-September 1988 (Citations from the NTIS Database) National Technical Information Service, Springfield, Virginia (United States) PB88-868260/GAR, 177 pp. (Sep. 1988) This bibliography contains citations concerning the nondestructive techniques for testing or examining ceramic materials and ceramic bodies for the detection of flaws or defects. Applications for testing ceramic gas turbine engine materials, high performance structural ceramic materials, and the use of scanning laser acoustic microscopy (SLAM) are presented. 41163
Baaklini, G. Y.; Slima, S.J.; Sanders, W.A.
Nondestructive evaluation of sintered ceramics National Aeronautics and Space Administration, Cleveland, Ohio (United States) Lewis Research Centre, N88-22416/7/GAR 11 pp. (May 1988) Radiography and several acoustic and thermoacoustic microscopy techniques are investigated for application to structural ceramics for advanced heat engines. A coniparison is made of the results obtained from the use of scanning acoustic
40
Olympus Kogaku Kogyo Kabushiki Kaisha
Acoustic lens for use in acoustic microscope British Patent No. GB2192281 (6 Jun. 1988) An acoustic lens, for use in an acoustic microscope, comprises a solid state medium for propagating an acoustic wave having a wavelength lambdaA and having opposed end surfaces, an electric-acoustic transducer applied on one end surface of the solid state medium and having a radius a, and a spherical lens portion formed in the other end surface of the solid state medium and having an aperture of a radius w. The length 1 and the aperture radius w is normalized by the transducer radius a such that Z = llambda/a 2 and W = w/a. Values of Z and W are selected from such a region in a first quadrant of a Z-W coordinate system that desired power and/or phase are obtained, except for a known region neighbouring a point Z= 1 and W= 1. 40727
Busse, G.
Characterisation through thermal waves: applications of optoaconstic and phototherrnal methods Ultrasonic Methods in Evaluation of I n h o m o g e n e o u s Materials, Proceedings, Erice, (Italy), 15-25 Oct. 1985, pp. 105-119. E d ited by A. Alippi and W.G. Mayer. N A T O A d v a n c e d Study Institute Series E A ppl i e d Sciences, Vol. 126, Martinus Nijhoff, 1987 This paper considers the use of thermal waves for non destructive testing, through optoacoustic or photothermal methods. The generation and detection of thermal waves is described as well as their physical characteristics. Scanned thermal wave inspection, or imaging is discussed and applications suggested.
Ashurov, A.M.; Madvaliev, U.; Proklov, V. V.; Beremzhanov, I.M.; Zhavoronkov, A.A.
40716
Photoacoustic microscope with optical scanning Instruments and E x p e r i m e n t a l Techniques, Vol. 31, No. 2, Pt. 2, pp. 439-442 (Oct. 1988) A scanning photoacoustic microscope with a unit for control of twodimensional optical scanning and formation of a photoacoustic image is presented. The control circuit and photoacoustic cell are described. The
NDT International February 1990