1.5.2 Nanomaterials
Nanomaterials are generally defined as those materials that have a characteristic length
scale (that is,particle diameter,grain size,layer thickness,etc.)smaller than 100 nm
(1 nm=10-9 m)Nanomaterials can be metallic,ploymeric,ceramic,electronic,or
composite.in this respect,ceramic powder aggregates of less than 100 nm on size,bilk
metals with grain size less than 100 nm,thin polymeric films with thickness less than
100 nm,and electronic wires with diameter less than 100 nm are all considered nanoma-terials
or nanostructured materials.at the nanoscale,the properties of the material are
neither that of the molecular or atomic level nor that of the bulk material.Although
a tremendous amount of research and development activities has been devoted to this
topic in the past decade,early research on nanomaterials dates back to the 1960s
when chemical flame furnaces were used to produce particles smaller than one
micron(1 micron=10-6 m = 10 3 nm)in size. the early applications of nanoma-terials
were as chemical catalysts and pigments,Metallurgists have always been
aware that by refining the grain structure of a metal to ultrafine (submicron)levels,
its strength and hardness increases significantly in comparison to the coarse-grained
(micron-size)bulk metal,For example, nanostructured pure copper has a yield
strength six times that of coarse-grained copper.
1.5.2 NanomaterialsNanomaterials are generally defined as those materials that have a characteristic lengthscale (that is,particle diameter,grain size,layer thickness,etc.)smaller than 100 nm(1 nm=10-9 m)Nanomaterials can be metallic,ploymeric,ceramic,electronic,or composite.in this respect,ceramic powder aggregates of less than 100 nm on size,bilkmetals with grain size less than 100 nm,thin polymeric films with thickness less than 100 nm,and electronic wires with diameter less than 100 nm are all considered nanoma-terialsor nanostructured materials.at the nanoscale,the properties of the material areneither that of the molecular or atomic level nor that of the bulk material.Althougha tremendous amount of research and development activities has been devoted to thistopic in the past decade,early research on nanomaterials dates back to the 1960swhen chemical flame furnaces were used to produce particles smaller than onemicron(1 micron=10-6 m = 10 3 nm)in size. the early applications of nanoma-terials were as chemical catalysts and pigments,Metallurgists have always been aware that by refining the grain structure of a metal to ultrafine (submicron)levels,its strength and hardness increases significantly in comparison to the coarse-grained(micron-size)bulk metal,For example, nanostructured pure copper has a yieldstrength six times that of coarse-grained copper.
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