Surface Roughness Of Substrate Research Articles

Preparation and Characterization of Thin‐Film Nanocomposite Membrane Incorporated with MoO3 Nanoparticles with High Flux Performance for Forward Osmosis

AbstractIn this research, thin film nanocomposite (TFN) membranes were developed using novel polyethersulfone– molybdenum oxide (PES–MoO3) nanocomposite substrate. The effects of MoO3 nanoparticles on the PES substrate morphologies, surface roughness, hydrophilicity, and water permeability were investigated by measuring the water contact angles, scanning electron microscope (SEM) imaging, FT‐IR spectroscopy, and atomic force microscope (AFM) analysis. The MoO3 nanoparticle modified membranes were used in the forward osmosis (FO) process with both PRO mode (the membrane active layer facing draw solution) and FO (the membrane active layer facing feed solution) mode. The results indicated enhanced water permeability of the modified membranes upon the MoO3 addition, leading to significant enhancement in the water flux and the desalination performance.

Textile Display with AMOLED Using a Stacked-Pixel Structure on a Polyethylene Terephthalate Fabric Substrate.

An active-mode organic light-emitting diode (AMOLED) display on a fabric substrate is expected to be a prominent textile display for e-textile applications. However, the large surface roughness of the fabric substrate limits the aperture ratio—the area ratio of the organic light-emitting diode (OLED) to the total pixel area. In this study, the aperture ratio of the AMOLED panel fabricated on the polyethylene terephthalate fabric substrate was enhanced by applying a stacked-pixel structure, in which the OLED was deposited above the organic thin-film transistor (OTFT) pixel circuit layer. The stacked pixels were achieved using the following three key technologies. First, the planarization process of the fabric substrate was performed by sequentially depositing a polyurethane and photo-acryl layer, improving the surface roughness from 10 μm to 0.3 μm. Second, a protection layer consisting of three polymer layers, a water-soluble poly-vinyl alcohol, dichromated-polyvinylalcohol (PVA), and photo acryl, formed by a spin-coating processes was inserted between the OTFT circuit and the OLED layer. Third, a high mobility of 0.98 cm2/V∙s was achieved at the panel scale by using hybrid carbon nano-tube (CNT)/Au (5 nm) electrodes for the S/D contacts and the photo-acryl (PA) for the gate dielectric, enabling the supply of a sufficiently large current (40 μA @ VGS = −10 V) to the OLED. The aperture ratio of the AMOLED panel using the stacked-pixel structure was improved to 48%, which was about two times larger than the 19% of the side-by-side pixel, placing the OLED just beside the OTFTs on the same plane.

Wetting kinetics and interfacial structure of AgCu alloy spreading on TB8 substrates

AgCu filler metal spreading over TB8 substrate under a high-purity argon atmosphere was conducted at 920 °C. Effects of surface roughness and topography of the substrate on the wetting kinetics were investigated. The interfacial microstructures of AgCu eutectic alloy/TB8 substrate solidified couples was analyzed by optical microscope, scanning electron microscope, energy dispersive spectrometer and transmission electron microscope. Results revealed that the substrate surface roughness and topography had significant influences on the wetting kinetics and spreading process. The spreading was preferential when AgCu molten metal over an anisotropically microstructured surface. When the surface of the substrate was not anisotropic, the spreading morphology was almost a perfect circle. An additional capillary driving force exists when the molten metal flows on the rough surface, which leads to a better wettability. The interfacial microstructure of the resolidified AgCu on the TB8 substrate was Ag(ss)/ Ti3Cu4/Ti2Cu/ /Ti(ss) + Ti2Cu/TB8, and the spreading edge domain near the triple-line is rich in Ag.

Effect of pretreatment on Al2O3 substrate by depositing Al2O3 film on the properties of Ni–Cr–Si based thin film resistor

In this study, a pretreatment on aluminum oxide substrate by sputtering with an aluminum oxide film is investigated to improve the surface roughness of a deposited NiCrSi (55/40/5) thin film resistor. Effect of sputtering parameters and thermal treatment on the deposited aluminum oxide film on aluminum oxide substrate are studied. Aluminum oxide thin film with Ar/O2 flow rate of (55/5) sccm shows the lowest surface energy at 41.5 J/m2 that would be helpful in improving the quality of the deposited resistive NiCrSi thin film. On the other hand, with increasing the thickness of aluminum oxide film, the surface roughness of the alumina substrate is observed to be significantly decreased and is quite helpful in improving the continuity of deposited resistive NiCrSi film. According to our investigations, developing a narrow distribution of high resistance thin film resistor by reducing the thickness of NiCrSi film is feasible when the aluminum oxide substrate was pretreated by sputtering aluminum oxide film and the continuity of NiCrSi thin film can be significantly improved, leading to a narrow resistance distribution of thin film resistor.

Polymer nanocomposite reinforced with selectively synthesized coiled carbon nanofibers

ABSTRACTCoiled carbon nanofiber were selectively synthesized over Inconel metal as substrate. Effect of different heating rates and substrate surface roughness on morphology of coiled carbon nanofibers was studied using various characterization techniques. After analysis of carbon growth, best heating rate for homogenous coiled growth was identified as 5°C min−1 with surface roughness of 1.7 µm for Inconel. The coiled carbon nanofibers were used as filler materials with different wt. % in polyurethane for fabrication of nanocomposite. Properties of nanocomposites and nanofibers were studied using FESEM and XRD. Mechanical properties were also investigated by nano indentation, wear and tensile testing. There was 114% and 48% increase in elastic modulus and hardness respectively. With increase in wt. % of carbon nanofibers there was also decrease in wear and increase in tensile strength of polymer nanocomposite.

Preparation of Irregular Silica Nanoparticles by the Polymer Templating for Chemical Mechanical Polishing of Sapphire Substrates

Irregular silica nanoparticles were prepared through polymer templating and their application on chemical mechanical polishing (CMP) of sapphire substrates was performed. Irregular silica nanoparticles were obtained by the chain structure of PEG200 and many oxygen functional groups. Silica seed particles can be rapidly coated through hydrogen bonding and also overlapped for two or more silica seed particles. The results show that the material removal rate of irregular silica nanoparticles increases by 58.7% compared to that of spherical silica nanoparticles. The surface roughness of the sapphire substrates measured by an Ambios Xi-100 surface profiler is 1.584 nm. Energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy revealed that some solid-state chemical reactions occurred during the CMP process. Possible mechanical effects of irregular silica nanoparticles in CMP process were also discussed.

Surface roughening of Al2O3/Al2O3-ceramic matrix composites by nanosecond laser ablation prior to thermal spraying

Al2O3/Al2O3 ceramic matrix composites are candidate materials for high-temperature applications such as gas turbines. As water vapor corrosion of Al2O3/Al2O3-CMC (ceramic matrix composite) is a major issue, the application of suitable environmental barrier coatings is inevitable. An important factor for coating adhesion, especially in thermal spraying, is mechanical interlocking. Therefore, a rough substrate surface is needed. Although it has been proven that laser ablation is a suitable method for surface preparation of metallic substrates, no studies on Al2O3/Al2O3-CMCs are available. Therefore, the suitability of surface preparation of an Al2O3/Al2O3-CMC by laser ablation for use prior to atmospheric plasma spraying was examined. The laser ablation threshold fluence for Al2O3/Al2O3-CMC was determined. The effects of different processing parameters on the surface were studied. Various surface morphologies were obtained, such as cauliflower and honeycomb structures. The samples were characterized by white light interferometry, laser microscopy, and scanning electron microscopy. The obtained surface structures were coated with Gd2Zr2O7. It was found that the adhesion strength of coatings on laser treated samples was drastically increased.

Study of Surface Roughness of Electronic Substrate on Abrasive Belt Grinding

Machining processing industries have continuously developed and improved technologies and processes to transform finished product to obtain better super finished product quality and thus increase products. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. Indeed, grinding is the process of removing metal by the application of abrasives which are bonded to form a rotating wheel or belt. When the moving abrasive particles contact the workpiece, they act as tiny cutting tools, each particle cutting a tiny chip from the workpiece. The abrasive belt grinding is efficient, economic, widely used and being said “universal grinding”. It can get high machining accuracy and surface quality. Surface quality is a very important aspect of machining quality and it is the most important parameter to measure the surface quality. Many factors affect the surface roughness such as performance of abrasive belt, the amount of abrasive belt grinding, hardness of contact wheel. And the most important one is the amount of grinding. For electronic packaging, before soldering, copper substrates have to be polished by both chemical and mechanical polishing. Therefore, this article is aimed at that status so that to design and manufacture a new abrasive belt grinding machine. And then the surfaces for soldering of Cu substrates are ground and polished using the machine. Finally, the surface roughness of copper substrates polished by the abrasive belt grinding machine is evaluated and compared with other grinding machines.

Enhanced adhesion of plasma-sprayed commercially pure titanium porous coatings to polished Mg-PSZ ceramic substrates.

The purpose of this study was to evaluate the suitability of a plasma sprayed titanium porous coating on polished magnesia-stabilized zirconia (Mg-PSZ) ceramic surfaces. We hypothesized that diffusion bonding was responsible for the adhesion of the coating to the ceramic substrate. Mg-PSZ tensile test coupons were vibratory polished (roughness Sa = 0.50 μm) or vibratory polished/lapped (Sa = 0.12 μm) before coating and testing. The exposed surfaces after tensile testing were examined by energy dispersive X-ray (EDX) analysis. Mg-PSZ shear test coupons were vibratory polished (Sa = 0.48 μm). As the surface roughness of the ceramic substrate decreased by a factor of 4.175, the coating tensile strength increased from 62.6 to 66.8 MPa, comparable to that of porous coated cobalt chromium (CoCr) and titanium (Ti-6Al-4V) coupons. EDX analyses found titanium everywhere on the ceramic surface after the titanium layer was pulled off with tensile testing, even on areas that appeared to be "clean" to the naked eye. This suggested that titanium oxide compounds were present at the interface, where the oxygen required could only result from diffusion bonding across the interface. Diffusion bonding may also explain the significantly higher amounts of zirconium on the coating surface that had been pulled off the smoother lapped ceramic coupons. The measured shear strength of porous-coated ceramic coupons was significantly higher than that of CoCr and Ti-6Al-4V coupons. The superior adherence of the titanium coating to Mg-PSZ suggests this process has great clinical potential in arthroplasty, especially for patients with metal sensitivity. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1925-1932, 2019.

Formation of antiphase boundaries in CuFe2O4 films induced by rough MgAl2O4 (001) substrates

Antiphase boundaries in spinel ferrites have been considered as the functional elements with great potential for applications in spintronic devices. Engineering the antiphase boundaries is a big challenge in experiments. Here, we report on that a high density of antiphase boundaries in CuFe2O4 films have been prepared on rough surface of MgAl2O4 (001) substrates. By means of advanced electron microscopy these antiphase boundaries are found to be of {011}14〈011〉-type and bound by interfacial dislocations with Burgers vector of a/4〈011〉 that contribute to relaxation of in-plane and out-of-plane lattice strain in the heterostructure. Our results provide evidence that the rough substrate surface can be applied for the formation of antiphase boundaries in the CuFe2O4/MgAl2O4 system to tune the magnetic and electrical transport properties of epitaxial spinel ferrite films.

Wear properties of esthetic dental materials against translucent zirconia.

To clarify the influence of translucent tetragonal zirconia polycrystals (TZP) on wear properties of esthetic dental materials, two-body wear test was performed using translucent TZP as abrader specimen, and bovine tooth enamel (BTE), two resin composites including hybrid filler (CRH) and nano filler (CRN), two glass ceramics including leucite reinforced feldspar porcelain (POR) and lithium disilicate (LDC), or translucent TZP as substrate specimen. After the wear test, wear volume were determined from substrate specimen and surface roughness were measured from abrader specimen. In addition, Vickers hardness was measured and surface morphologies were observed after wear test using a scanning electron microscope. The wear volume of the esthetic dental material against translucent TZP was greater in glass ceramics (POR, LDC), smaller in resin composite (CRH, CRN) and BTE, and no wear in translucent TZP. Microstructures of the esthetic dental material may play a crucial role for wear behavior against translucent TZP.

Electric field control of magnetism in Si3N4 gated Pt/Co/Pt heterostructures

In this work, we show the presence of a magnetoelectric coupling in silicon-nitride gated Pt/Co/Pt heterostructures using X-ray photoemission electron microscopy. We observe a change in magnetic anisotropy in the form of domain wall nucleation and a change in the rate of domain wall fluctuation as a function of the applied electric field to the sample. We also observe the coexistence of in-plane and out-of-plane magnetization in Pt/Co/Pt heterostructures in a region around the spin reorientation transition whose formation is attributed to substrate surface roughness comparable to the film thickness; with such domain configuration, we find that the in-plane magnetization is more sensitive to the applied electric field than out-of-plane magnetization. Although we find an effective magnetoelectric coupling in our system, the presence of charge defects in the silicon nitride membranes hampers the systematic electrostatic control of the magnetization.

Comparative study of surface modification techniques through average flank wear in high speed steel tools coated with thin TiN film

Hard coatings are usually applied to improve high speed steel (HSS) tools performance. However, to achieve this aim, a good adhesion between coating film and substrate is necessary. The coating failure, associated to the lack of adhesion to the substrate, can lead to tool premature wear, reducing its efficiency. The surface modification can improve the coating film adhesion levels by modifying substrates surface roughness, and then, ensuring better anchorage of the deposited layer. In this research two techniques of superficial modification, planar sputtering and chemical polishing, were compared. The sputtering uses plasma application, where cations formed in the reactor collide with samples surface, removing material from it. For chemical polishing, it was used acid and alkaline solutions. After surface treatments, all roughness levels were measured using a roughness tester. The Cathodic Cage Plasma Nitriding (CCPN) technique was used to deposit a TiN film on tools surface. Then, X-ray diffraction, Vickers microhardness and SEM tests were carried out to verify the presence of deposited film, as well as its thickness and mechanical properties, and then, machining tests with SAE 1045 steel where performed, applying the coated tools. Optical microscopy was carried out to track average flank wear up to 0.3 mm, characterizing the end of tool life. It can be observed that all the coated tools obtained an increase in its life, registering the variances according to the different roughness profiles. The best results were verified for chemical polishing with acid solution treatment condition, as it allowed longer machining time with less flank wear.

The elastic-plastic contact behavior of rough surfaces with hard coatings

Abstract An elastic-plastic coated rough surface contact model is presented, which incorporates existing single coated asperity contact models in a GW-based statistical multi-coated-asperity surface model. Effects of the coating thickness and its material properties as well as the substrate surface roughness on the mode of the coated surface contact deformation and its contact behavior are investigated through a qualitative parametric analysis. An equivalent plasticity index for the coated surface contact is defined to determine the mode of the coated surface contact deformation, which mainly depends on the coating material properties and the substrate surface roughness. It is found that a coated surface with a thicker, stiffer, harder coating and a rougher substrate has a higher separation and smaller real contact area under a given load.

Study of CuO Nanowire Growth on Different Copper Surfaces

Cupric oxide (CuO) nanowires were produced by thermal oxidation of copper surfaces at temperatures up to 450 °C. Three different surfaces, namely a copper foil as well as evaporation deposited copper and an application relevant sputtered copper film on Si(100) substrates were characterized ex-situ before and after the experiment. The development of oxide layers and nanowires were monitored in-situ using grazing incidence small angle X-ray scattering. The number density of nanowires is highest for the sputtered surface and lowest for the surface prepared by evaporation deposition. This can be linked to different oxide grain sizes and copper grain boundary diffusions on the different surfaces. Small grains of the copper substrate and high surface roughness thereby lead to promoted growth of the nanowires.

Effects of complex graphite-like carbon coating on gear vibration noise

Abstract In this paper, the effects of substrate surface roughness and the addition of yttrium, cerium and tantalum on thickness uniformity of graphite-like carbon (GLC) coatings on gears were studied by magnetron sputtering method using mosaic targets. And noise reduction effects of gear pump deposited with complex GLC coatings were evaluated at different rotate speeds. The results showed that target-substrate distance, sputtering angle and surface roughness had influences on thickness uniformity of GLC coatings on gear. The introduction of elements Y, Ce and Ta into GLC coatings could effectively improve their thickness uniformity. The complex GLC coating with optimal thickness uniformity on gear exhibited significantly reduction effect for gear noise and the reduction effect for axial vibration was better than that of radial vibrations. Compared with uncoated gears, the noise for the coated gears was decreased by 10 dB at 2000 rpm. Good high-frequency noise reduction was obtained, which could be decreased by 19 dB in the range of 4000–10,000 Hz.

PEG-assisted Sol-gel Synthesis of Compact Nickel Oxide Hole-Selective Layer with Modified Interfacial Properties for Organic Solar Cells.

As a p-type metal oxide, nickel oxide (NiO) has been extensively utilized for providing a favorable hole transport pathway in organic solar cells (OSCs). To obtain higher crystallinity, a post-annealing process at high temperature is required for the NiO layer. Therefore, fluorine-doped tin oxide (FTO) glass has been widely used for the substrate of NiO. However, the rough surface of the FTO substrate deteriorates the interfacial properties of the NiO layer, which hinders efficient charge extraction in OSCs. In this study, a facile polyethylene glycol (PEG)-assisted sol-gel synthesis of the compact NiO layer as the hole-selective layer is demonstrated. The compact NiO layer has a significantly uniform and smooth surface morphology, facilitating better interfacial properties for favorable charge transport. The modified interfacial properties outstandingly promote the charge migration and recombination blocking in OSCs. In addition, a hybrid structure with compact NiO and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is designed to form a cascade charge extraction and passivate possible pinholes on the NiO layer. Consequently, the compact NiO layer enhances all the parameters determining the power conversion efficiency, including the open-circuit potential (Voc), short-circuit current density (Jsc), and fill factor (FF).

Hygroexpansion and Surface Roughness Cause Defects and Increase the Electrical Resistivity of Physical Vapor Deposited Aluminum Coatings on Paper

Aluminum coatings, which are applied by physical vapor deposition (PVD), have to be virtually defect-free in barrier applications for the packaging industry. When aluminum is applied to paper, hygroexpansion and substrate roughness can impair the aluminum coating. Neither effect is easy to detect by microscopy, but both can manifest as an increase in electrical resistance. Here, we quantified the effect of substrate paper hygroexpansion and surface roughness on the effective resistivity ρEFF of aluminum coatings. The sheet resistance of aluminum coated onto four different rough paper surfaces was measured via eddy currents at different relative humidity (0%–95%). The mass of aluminum per unit area was determined by inductively-coupled plasma mass spectrometry (ICP–MS). We calculated ρEFF based on the measured resistance and aluminum mass per unit area, combined with a value for aluminum density from the literature. The substrate roughness was proportional to ρEFF. Relative humidity correlated with the moisture content of the paper substrate according to the Guggenheim, Anderson, and De Boer (GAB) equation, whereas the moisture content showed a linear correlation with hygroexpansion. At relative humidity of up to 50%, hygroexpansion was linearly correlated with the increase in ρEFF, which is related to the mechanical straining and deformation of aluminum. At higher humidity, aluminum started to crack first on rough substrates and later on smooth substrates. The increase in ρEFF was larger on rough substrates. The findings highlight the need for information about substrate roughness, humidity, and hygroexpansion when eddy current measurement results are compared, and will help to ensure that aluminum coatings, applied by PVD, are defect-free.

Experimental investigation of tribo-mechanical and chemical properties of TiN PVD coating on titanium substrate for biomedical implants manufacturing

Tribological, mechanical, and chemical properties of the TiN coatings on Ti substrate were experimentally investigated for implant applications. X-ray diffraction (XRD) demonstrated that the principal crystal structure of TiN coating was (111) preferred orientation with FCC structure. Experimental evaluation was conducted at two substrate surface roughness, i.e., 0.1 μm and 0.4 μm. TiN coatings having 0.4-μm substrate surface roughness and approximately 3.3-μm coating thickness demonstrated optimum results of adhesion strength, hardness, coefficient of friction, wear rate, and corrosion rate in simulation body fluid (SBF). The selected TiN-coated sample exhibited maximum of 16.585 GPa hardness, 238.7 GPa elastic modulus, approximately 20 N adhesion, and 0.088 coefficient of friction. TiN coating showed approximately 8 times more corrosion resistance and 4 times more wear resistance than the bare titanium substrate. Energy dispersive spectroscopy (EDS) analysis of the wear tracks of TiN coating in SBF showed no presence of any harmful ingredients and confirmed its biocompatibility over the usage time in SBF. TiN-coated sample with higher substrate surface roughness (0.4 μm) demonstrated better tribo-mechanical properties and could reduce the cost of production than the conventionally used TiN-coated Ti implants of lower substrate surface roughness (0.1 μm).

Investigation of Austenitic Stainless Steel Coatings on Mild Steel Produced by Friction Surfacing Using a Conventional CNC Machining Center

The friction surfacing process allows deposition of similar and dissimilar coatings in the solid state, avoiding some of the problems associated with conventional coating methods in which fusion is involved. In the present work, a viability assessment of producing AISI 304 austenitic stainless steel coatings on AISI 1020 low-carbon steel substrates using a machining center with Computerized Numerical Control (CNC) instead of dedicated friction surfacing equipment was pursued. The influence of consumable rod rotation and translation speed, as well as substrate surface roughness on the geometry and adhesion of the coatings was evaluated. The microstructure of the stainless steel coatings was investigated by optical and scanning electron microscopy, while microhardness analysis was performed in order to evaluate properties near the coating-substrate interface. Finally, the electrochemical corrosion behavior of the coatings and the as-received AISI 304 steel consumables in 0.5M H2SO4 solution containing naturally dissolved O2 was compared. The results revealed that the friction surfacing process can be applied in non-specialized machinery, since the manufactured coatings exhibited good adhesion and corrosion resistance. The formation of hard bands in the coatings was identified near the interface region and the adhesion of the coatings was found to be influenced by initial substrate roughness.