15524

1563 دكتري

دكتري

مهندسي نانومواد

اصفهان : دانشگاه صنعتي اصفهان

1398

سيزده، 123 ص: مصور، جدول، نمودار

علي شفيعي

فتح الله كريم زاده، رضا شجاع رضوي

محمد حسين عنايتي، بهروز موحدي، مهدي رنجبر

1399/01/25

كتابنامه

مواد

مهندسي مواد

1399/01/31

2603905

Abstract In this thesis formation of uniform and large area micro nanostructures on pure aluminumsurfaces using a continuous wave laser irradiation is presented Gold nanolayer coatingwas utilized as a confinement layer for controlling the possible hydrodynamic phenomenain a molten area Dependency of the laser induced morphology on the thickness of a goldcoating was investigated in this regard Results showed that the formation of uniformstructures of average sizes of 50 nm 5 m on aluminum surface was possible following theirradiation of a continuous wave CO2 laser delivering 130 W beam power Alterations ofthe surface morphology brought about an increase in specific absorption peaks at the UVregion and the appearance of an absorption peak in the visible range In addition thesestructure covered surfaces provided interesting reflection behaviors in different spectralareas which can clearly reflect their high potential to be used as selective solar absorbers The results of this investigation indicated that optical characteristics such as absorption andemission coefficients as well as factor were 0 98 0 13 and 7 53 respectively It cantherefore be concluded that this process can be considered an efficient and fast technique tofabricate selective solar absorbers Investigation results of the fabrication of Au Al2O3core shell nanoparticles were demonstrated by one step and a very fast method withcontinuous wave fiber laser ablation on a pure Al plate coated gold nanolayer filmimmersed into ethanol The core and shell of these nanoparticles contained completecrystalline structures Crystal structure identification calculation of lattice parameter andinterplanar spacing of core shell nanoparticles were performed by selected area electrondiffraction technique The shape of these nanoparticles was roughly spherical and theiraverage size was approximately 20 nm These core shell nanoparticles indicated acombined absorption spectrum containing two significant peaks in UV visible IR ranges Also the optical band gap was 2 9 eV which was in common and excellent semiconductorsrange This thesis is devoted to fabricate superhydrophobic surface on pure Al with goldnanolayer coating by irradiation of the continuous wave fiber laser ablation inside ethanolenvironment Microstructures combined with micro nanoparticles on Al surface wascreated by laser ablation as well The shape of these nanoparticles was roughly spherical In addition the static water contact angle technique to evolution of wettability propertieswas employed These fabricated structures exhibited superhydrophobic behavior withwater contact angle up to 152 2 Moreover influence of thickness of gold coating onlaser ablation process and manufacture of hydrophobic surface was studied in detailed These innovative core shell nanoparticles were characterized by transmission electronmicroscopy selected area electron diffraction technique Optical properties such asabsorption spectroscopy in UV visible IR ranges were investigated and calculation of bandgap energy of nanoparticles was performed The morphology and chemical compositionsof the surface substrate were investigated by a scanning electron microscopy atomic forcemicroscopy grazing test of the X ray diffraction and energy dispersive spectroscopy Keywords CO2 laser Fiber laser Continuous wave laser Aluminum Gold coating Nanostructure Core shell nanoparticle Optical property Superhydrophobic surface

علي شفيعي

فتح الله كريم زاده، رضا شجاع رضوي

محمد حسين عنايتي، بهروز موحدي، مهدي رنجبر