Andrew Briggs and Oleg Kolosov
- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199232734
- eISBN:
- 9780191716355
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199232734.001.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
Acoustic microscopy enables you to image and measure the elastic properties of materials with the resolution of a good microscope. By using frequencies in the microwave range, it is possible to make ...
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Acoustic microscopy enables you to image and measure the elastic properties of materials with the resolution of a good microscope. By using frequencies in the microwave range, it is possible to make the acoustic wavelength comparable with the wavelength of light, and hence to achieve a resolution comparable with an optical microscope. The contrast gives information about the elastic properties and structure of the sample. Since acoustic waves can propagate in materials, acoustic microscopy can be used for interior imaging, with high sensitivity to defects such as delaminations. Solids can support both longitudinal and transverse acoustic waves. At surfaces a combination of the two known as Rayleigh waves can propagate, and in many circumstances these dominate the contrast in acoustic microscopy. Contrast theory accounts for the variation of signal with defocus, V(z). Acoustic microscopy can image and measure properties such as anisotropy and features such as surface boundaries and cracks. A scanning probe microscope can be used to detect ultrasonic vibration of a surface with resolution in the nanometre range, thus beating the diffraction limit by operating in the extreme near‐field. This 2nd edition of Acoustic Microscopy has a major new chapter on the technique and applications of acoustically exited probe microscopy.Less
Acoustic microscopy enables you to image and measure the elastic properties of materials with the resolution of a good microscope. By using frequencies in the microwave range, it is possible to make the acoustic wavelength comparable with the wavelength of light, and hence to achieve a resolution comparable with an optical microscope. The contrast gives information about the elastic properties and structure of the sample. Since acoustic waves can propagate in materials, acoustic microscopy can be used for interior imaging, with high sensitivity to defects such as delaminations. Solids can support both longitudinal and transverse acoustic waves. At surfaces a combination of the two known as Rayleigh waves can propagate, and in many circumstances these dominate the contrast in acoustic microscopy. Contrast theory accounts for the variation of signal with defocus, V(z). Acoustic microscopy can image and measure properties such as anisotropy and features such as surface boundaries and cracks. A scanning probe microscope can be used to detect ultrasonic vibration of a surface with resolution in the nanometre range, thus beating the diffraction limit by operating in the extreme near‐field. This 2nd edition of Acoustic Microscopy has a major new chapter on the technique and applications of acoustically exited probe microscopy.
Vikas Mittal
- Published in print:
- 2011
- Published Online:
- September 2011
- ISBN:
- 9780199581924
- eISBN:
- 9780191728853
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199581924.003.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
Polymer nanocomposites are the materials with much improved properties than the constituent polymers. The nanoscale dispersion of the filler in the polymer matrix leads to the generation of ...
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Polymer nanocomposites are the materials with much improved properties than the constituent polymers. The nanoscale dispersion of the filler in the polymer matrix leads to the generation of tremendous amount of interfacial contacts between the organic and inorganic components. The polymer matrices generally used for the synthesis of polymer nanocomposites are non-biodegradable, which poses an environmental hazard. Thus, to generate more environmentally friendly materials, as well as to decrease the dependence from the fossil based resources, use of a number of biopolymers has been developed in the recent years. As the properties of such polymer are sometimes inferior to the commercial non-biodegradable polymers, thus, nanocomposites of such biopolymers have been developed to improve performance. Polymers which are finding increasing use in the composite technology to replace the non-biodegradable polymers include starch, cellulose, poly(lactic acid), poly(hydroxy alkanoates), pectin, chitosan, etc. The other polymers which though have fossil based sources but are still biodegradable incuse poly(caprolactone), poly(butylene succinate) etc. Significant improvement sin the mechanical, barrier and thermal properties have been reported in such bio-nanocomposites as compared to pure polymer. Biodegradation of the polymer after the incorporation of the clay has also been mostly observed to enhance, but on some occasions, it has also been observed to decrease, but still happening in principle. Thus, such bio-nanocomposites represent potentially high value materials of the future.Less
Polymer nanocomposites are the materials with much improved properties than the constituent polymers. The nanoscale dispersion of the filler in the polymer matrix leads to the generation of tremendous amount of interfacial contacts between the organic and inorganic components. The polymer matrices generally used for the synthesis of polymer nanocomposites are non-biodegradable, which poses an environmental hazard. Thus, to generate more environmentally friendly materials, as well as to decrease the dependence from the fossil based resources, use of a number of biopolymers has been developed in the recent years. As the properties of such polymer are sometimes inferior to the commercial non-biodegradable polymers, thus, nanocomposites of such biopolymers have been developed to improve performance. Polymers which are finding increasing use in the composite technology to replace the non-biodegradable polymers include starch, cellulose, poly(lactic acid), poly(hydroxy alkanoates), pectin, chitosan, etc. The other polymers which though have fossil based sources but are still biodegradable incuse poly(caprolactone), poly(butylene succinate) etc. Significant improvement sin the mechanical, barrier and thermal properties have been reported in such bio-nanocomposites as compared to pure polymer. Biodegradation of the polymer after the incorporation of the clay has also been mostly observed to enhance, but on some occasions, it has also been observed to decrease, but still happening in principle. Thus, such bio-nanocomposites represent potentially high value materials of the future.
C. Mathew Mate and Robert W. Carpick
- Published in print:
- 2019
- Published Online:
- October 2019
- ISBN:
- 9780199609802
- eISBN:
- 9780191747724
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780199609802.003.0012
- Subject:
- Physics, Condensed Matter Physics / Materials, Atomic, Laser, and Optical Physics
This chapter outlines common mechanisms that contribute to wear, which is broadly defined to be any form of surface damage caused by rubbing one surface against another. Such wear mechanisms include ...
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This chapter outlines common mechanisms that contribute to wear, which is broadly defined to be any form of surface damage caused by rubbing one surface against another. Such wear mechanisms include delamination wear, adhesive wear (where adhesion followed by plastic shearing plucks the ends off the softer asperities, typically described by Archard’s law), abrasive wear (where hard particles or asperities gouge a surface and displace material), and oxidative wear (where surfaces react with atmospheric oxygen prior to being worn). Sliding conditions often determine which wear mechanism dominates, with the main factors being temperature, sliding velocity, oxidation, plasticity, loading force, and mechanical stresses. How wear rates respond to changes to these factors can be diagramed on a wear map. The last part of the chapter discusses how transition state theory can describe nanoscale wear by atomic attrition, and how plasticity and fracture occur at the nanoscale.Less
This chapter outlines common mechanisms that contribute to wear, which is broadly defined to be any form of surface damage caused by rubbing one surface against another. Such wear mechanisms include delamination wear, adhesive wear (where adhesion followed by plastic shearing plucks the ends off the softer asperities, typically described by Archard’s law), abrasive wear (where hard particles or asperities gouge a surface and displace material), and oxidative wear (where surfaces react with atmospheric oxygen prior to being worn). Sliding conditions often determine which wear mechanism dominates, with the main factors being temperature, sliding velocity, oxidation, plasticity, loading force, and mechanical stresses. How wear rates respond to changes to these factors can be diagramed on a wear map. The last part of the chapter discusses how transition state theory can describe nanoscale wear by atomic attrition, and how plasticity and fracture occur at the nanoscale.
Roy Livermore
- Published in print:
- 2018
- Published Online:
- April 2018
- ISBN:
- 9780198717867
- eISBN:
- 9780191860492
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198717867.003.0007
- Subject:
- Physics, Geophysics, Atmospheric and Environmental Physics, History of Physics
Well into the 1970s, the poor old geologists were still refusing to mend their ways, despite what they regarded as a ‘reign of terror’ by geophysicists. ‘Plate tectonics is fine’, they admitted ...
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Well into the 1970s, the poor old geologists were still refusing to mend their ways, despite what they regarded as a ‘reign of terror’ by geophysicists. ‘Plate tectonics is fine’, they admitted grudgingly, ‘but it does not work in my area’. One of the most progressive, John Dewey, later recalled that, on being shown a long marine magnetic anomaly profile in 1965, and having its implications spelled out to him by geophysicists, he was only mildly impressed and remarked ‘Interesting, but keep it in the oceans and don’t let it onto the continents.’ The reaction of the geophysicists, who ‘muttered darkly about the ignorance and narrow-mindedness of geologists’, was, he recollected, ‘slightly scathing’.Less
Well into the 1970s, the poor old geologists were still refusing to mend their ways, despite what they regarded as a ‘reign of terror’ by geophysicists. ‘Plate tectonics is fine’, they admitted grudgingly, ‘but it does not work in my area’. One of the most progressive, John Dewey, later recalled that, on being shown a long marine magnetic anomaly profile in 1965, and having its implications spelled out to him by geophysicists, he was only mildly impressed and remarked ‘Interesting, but keep it in the oceans and don’t let it onto the continents.’ The reaction of the geophysicists, who ‘muttered darkly about the ignorance and narrow-mindedness of geologists’, was, he recollected, ‘slightly scathing’.
