Effect Of Substrate Porosity Research Articles

Characterization of superhydrophobic a-C:F thin film deposited on porous silicon via laser ablation of a PTFE target

Fluorinated amorphous carbon (a-C:F) thin films are deposited on both flat silicon and porous silicon (PS) surfaces via laser ablation of a polished polytetrafluoroethylene (PTFE). Porous silicon (PS) is prepared by anodic etching of p-type silicon wafers in HF based solution. The film deposited on the flat silicon surface exhibits a highly hydrophobic state with water contact angle (WCA) of ~146°. In comparison, the surface of film deposited on PS layer shows a roll-off superhydrophobic state, where the water droplet is seen to roll off without wetting its surface with contact angle hysteresis of ~4.5°. Micro-Raman results show that the graphite domain of the film deposited on PS has higher disorder level and lower average gain size. The effect of substrate porosity on chemical composition of deposited films has been investigated by using both Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). It is found that the porous substrate improves the incorporation of the fluorine into the film. Atomic force microscopy (AFM) results revealed that the film deposited on PS has higher surface roughness and lower grain size as compared to the film deposited on flat silicon surface.

Influence of mesoporous substrate morphology on the structural, optical and electrical properties of RF sputtered ZnO layer deposited over porous silicon nanostructure

Morphological, optical and transport characteristics of the RF sputtered zinc oxide (ZnO) thin films over the mesoporous silicon (PS) substrates have been studied. Effect of substrate porosity on the grain growth and transport properties of ZnO has been analyzed. Physical and optical properties of ZnO–PS structures were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence (PL) spectroscopy. Our experimental results indicate that on changing porosity of the PS substrates, regularity of the spatial distribution of the ZnO nanocrystallites can be controlled. While the morphology and grain size of ZnO depended strongly on the morphology and pore size of the PS substrates, the rectifying factors of the metal semiconductor junction were found to be different by a factor of 3. The deposition of semiconducting oxides on such mesoporous substrates/templates offers the possibility to control their properties and amplify their sensing response.

Effect of substrate porosity on photoluminescence properties of ZnS films prepared on porous Si substrates by pulsed laser deposition

ZnS films were deposited on porous Si (PS) substrates with different porosities by pulsed laser deposition. The photoluminescence spectra of the samples were measured to study the effect of substrate porosity on luminescence properties of ZnS/porous Si composites. After deposition of ZnS films, the red photoluminescence peak of porous Si shows a slight blueshift compared with as-prepared porous Si samples. With an increase of the porosity, a green emission at about 550 nm was observed which may be ascribed to the defect-center luminescence of ZnS films, and the photoluminescence of ZnS/porous Si composites is very close to white light. Good crystal structures of the samples were observed by x-ray diffraction, showing that ZnS films were grown in preferred orientation. Due to the roughness of porous Si surface, some cracks appear in ZnS films, which could be seen from scanning electron microscope images.

Effect of Substrate Porosity on the Coating Adhesion of Iron Sintered Plated Parts with Infiltration Pretreatment

Plating of the sintered components has some problems due to interconnected porosities in those parts. In this research, iron-based sintered specimens infiltrated with copper were used. The pretreated specimens were then plated with nickel and the adhesion of coated layer to substrate was investigated. The results showed that the adhesion of coated layer in copper infiltrated iron sintered components is independent of substrate initial density.

Effect of substrate porosity on the corrosion behaviour of electro less nickel-phosphorus coated powder metallurgy iron compacts and strip

Powder metallurgy (PM) sintered iron compacts having 2-9% porosity, and full density PM iron strip were electro less coated successfully with nickel-phosphorus alloy from baths containing sodium hypophosphite. Corrosion behaviour of such specimens in l·0M HCl was investigated. It was shown that anodic and cathodic polarisation plots of such PM iron specimens, irrespective of substrate porosity exhibit Tafel behaviour. Corrosion rates of PM iron compacts of 2-9% porosity and full density strip coated with electro less nickelphosphorus alloy for shorter periods, of the order of 0·5 h increase with substrate porosity. However, the corrosion rate of such PM iron compacts and strip coated for more than 0·5 h, first increases with substrate porosity and then remains practically constant.

Effect of substrate porosity on the corrosion behaviour of electro less nickel-phosphorus coated powder metallurgy iron compacts and strip

Powder metallurgy (PM) sintered iron compacts having 2-9% porosity, and full density PM iron strip were electro less coated successfully with nickel-phosphorus alloy from baths containing sodium hypophosphite. Corrosion behaviour of such specimens in l·0M HCl was investigated. It was shown that anodic and cathodic polarisation plots of such PM iron specimens, irrespective of substrate porosity exhibit Tafel behaviour. Corrosion rates of PM iron compacts of 2-9% porosity and full density strip coated with electro less nickelphosphorus alloy for shorter periods, of the order of 0·5 h increase with substrate porosity. However, the corrosion rate of such PM iron compacts and strip coated for more than 0·5 h, first increases with substrate porosity and then remains practically constant.