The Role of SiO2 Gas in the Operation of Anti-Corrosion Coating Produced by PVD

This study examined theSiO2 gas present in the coatings used in corrosion industry.These layers have been created by physical vapor deposition (PVD), with an appropriate performance. Sublimation of SiO2is used to protect PVD aluminum flakes from water corrosionand to generate highly porous SiO2 flakes with holes in the nanometer range. SiOx/Al/SiOx sandwiches were made as well as Ag loaded porous SiO2 as antimicrobial filler

A Comparison between Thin-Film Transistors Deposited by Hot-Wire Chemical Vapor Deposition and PECVD

The effect of new growth techniques on the mobility and stability of amorphous silicon (a-Si:H) thin film transistors (TFTs) has been studied. It was suggested that the key parameter controlling the field-effect mobility and stability is the intrinsic stress in the a-Si:H layer. Amorphous and microcrystalline silicon films were deposited by radiofrequency plasma enhanced chemical vapor deposition (RF-PECVD) and hot-wire chemical vapor deposition (HW-CVD) at 100 ºC and 25 ºC. Structural properties of these films were measured by Raman Spectroscopy. Electronic properties were measured by dark conductivity, σd, and photoconductivity, σph. For amorphous silicon films deposited by RF-PECVD on PET, photosensitivity's of >105 were obtained at both 100 º C and 25 ºC. For amorphous silicon films deposited by HW-CVD, a photosensitivity of > 105 was obtained at 100 ºC. Microcrystalline silicon films deposited by HW-CVD at 95% hydrogen dilution show σph~ 10-4 Ω-1cm-1, while maintaining a photosensitivity of ~102 at both 100 ºC and 25 ºC. Microcrystalline silicon films with a large crystalline fraction (> 50%) can be deposited by HW-CVD all the way down to room temperature

The effects of extremely low frequency pulsed electromagnetic field on collagen synthesis of rat skin: A biochemical and histoligical approach

The efficacious effects of pulsed electromagnetic field (PEMF) under the certain field parameters like frequency and the field intensity have been reported for various tissue and molecules. Since collagen is found abundantly in most tissue structures, this research was designed to further investigate the effects of extremely low frequency (ELF) PEMF on the synthesis of the epidermal collagen. To do the task, six groups of animals each consisting of eight mature male rats were selected randomly as one group for the control and five for the test. The field was generated by using a parallel set of Helmholtz coil. The first set of experiments was carried out at the peak intensity of 2 mT (milli Tesla) for different frequencies of 25, 50 and 100 Hz. Since the most effective frequency turned out to be 25 Hz, another set of experiment was conducted using this frequency and two different field intensities of 1 and 4 mT. The field was applied for 2.5 h/day lasting for 8 days, keeping the same procedure for the control group except for the field turned off. On the ninth day, the rats were sacrificed and the skin samples from the dorsal region were taken for biochemical assessment of collagen by measuring hydroxyproline content using Stegeman-Stalder method and histological assessment. The data indicated that pulsed electromagnetic field of 2 mT at 25 Hz increased the collagen synthesis (P<0.05). The other intensities and frequency setting did not have much distinguishable effect, however, at the frequency of 25 Hz and 4 mT, the field effect on the collagen increase was also noticeable. It was concluded that applying the field parameters of 25 Hz and 2 mT peak intensity for 2.5 h/day during eight days rendered a significant increase in collagen synthesis in rat skin. Histological observations were consistent with the biochemical findings

Synthesis of Zinc Oxide Nanoparticles and Their Effect on the Compressive Strength and Setting Time of Self-Compacted Concrete Paste as Cementitious Composites

In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength

Properties of Silicon Dioxide Film Deposited By PECVD at Low Temperature/Pressure

conventional plasma enhanced chemical vapor deposition (PECVD) at low temperature/pressure with silane (SiH4) and nitrous oxide (N2O) as precursor gases. The ellipsometer and stress measurement system were used to test the thickness and refractive index uniformity of the SiO2 film fabricated. The effects of radio frequency (RF) power chamber pressure and N2O/SiH4 flow ratio on the properties of SiO2 film were studied. The results show that the refractive index of SiO2 film is mainly determined by N2O/SiH4 flow ratio .Moreover, the formation of SiO2 thin films is confirmed by Fourier transform infrared (FTIR) spectroscopy. The thickness and refractive indices of the films measured by ellipsometry C-V measurement show that the electrical properties are directly related to process parameters and Si/SiO2 interface. The MIS structures were also fabricated from optimized SiO2 layer to study C-V measurement and to estimate interface, oxide and effective border traps density. The deposited SiO2 films have good uniformity, compact structure, high deposition rate, low deposition temperature and controllable stress, which can be widely, used in semiconductor devices.  http://dx.doi.org/10.5937/metmateng1402089

The role of PECVD hard coatings on the performance of industrial tools

The advantages of the application of hard coatings, which are well knownfor cutting tools, are to a much lesser extent explored for casting, extrusion, molding and forming tools. Increasing the lifetime of these tools is an important task in surface engineering because of complex loading conditionsand often complicated tool geometry. The plasma-enhanced chemical vapor deposition (PECVD) technique is well suited to deposit hard coatings onto large dies and moulds. The aim of this study was to discuss deposition processes suitable for coating of the often large three-dimensional molds and dies used in metal forming. Furthermore, results obtained using different hard coatings in industrial applications for several case studies like aluminum pressure die-casting; plastics injection molding and sheet metal forming are presented and discussed. For best coating performance, a careful optimization of both substrate pretreatment and coating deposition is necessary. The plasma-enhanced chemical vapor deposition (PECVD) technique shows advantages for these applications because of the high flexibility in pre-treatment using chemical etching and plasma-nitriding, because of its ability to coat large complexly shaped tools and because of the possibility of deposition of low-chlorine containing low-friction coatings.  http://dx.doi.org/10.5937/metmateng1401015