tailieunhanh - Báo cáo hóa học: " Elastic Properties of 4–6 nm-thick Glassy Carbon Thin Films"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Elastic Properties of 4–6 nm-thick Glassy Carbon Thin Films | Nanoscale Res Lett 2010 5 14-19 DOI S11671-009-9435-2 NANO EXPRESS Elastic Properties of 4-6 nm-thick Glassy Carbon Thin Films M. P. Manoharan H. Lee R. Rajagopalan H. C. Foley M. A. Haque Received 28 May 2009 Accepted 2 September 2009 Published online 23 September 2009 to the authors 2009 Abstract Glassy carbon is a disordered nanoporous form of carbon with superior thermal and chemical stability in extreme environments. Freestanding glassy carbon specimens with 4-6 nm thickness and nm average pore size were synthesized and fabricated from polyfurfuryl alcohol precursors. Elastic properties of the specimens were measured in situ inside a scanning electron microscope using a custom-built micro-electro-mechanical system. The Young s modulus fracture stress and strain values were measured to be about 62 GPa 870 MPa and respectively showing strong size effects compared to a modulus value of 30 GPa at the bulk scale. This size effect is explained on the basis of the increased significance of surface elastic properties at the nanometer length-scale. Keywords Young s modulus Glassy carbon Thin film Size effect Introduction Nanoporous glassy carbon derived from pyrolysis of the polymer precursor polyfurfuryl alcohol PFA is a M. P. Manoharan M. A. Haque El Department of Mechanical Nuclear Engineering The Pennsylvania State University University Park PA 16802 USA e-mail mah37@ H. Lee R. Rajagopalan Materials Research Institute The Pennsylvania State University University Park PA 16802 USA H. C. Foley Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA non-graphitizing carbon 1 that can act as a molecular sieve and has potential applications in catalysis 2 and air separation 3 . Bulk glassy carbon has been commercially used as an electrode material for over half a century due to its excellent thermal stability and resistance to chemical attacks. These properties also make it more suitable than zeolite .