Smooth Finish Research Articles

A multi-aspect study of commercial coatings under the effect of surface roughness and fouling

The paper presents an experimental study of surface and hydrodynamic characteristics for biocidal, non-biocidal antifouling coatings and hard coatings. In the study both smooth panels (Rt(50)≈40-90 μm) and panels with roughness commonly found on ship hulls (Rt(50)≈110-125 μm) were used. Measurements of drag were obtained from torque measurements in a rotating disk rig and the biocide content (Cu) of the coatings was measured using X-Ray Fluorescence instrument. The results show that Cu concentrations in coatings were sufficient to deter hard fouling such as by barnacles. The results from the drag measurements show that over the range of investigated test velocities, poorly applied antifouling biocidal coating with an induced roughness (Rt(50) = 116 μm) caused on average 13% higher moment coefficient (Cm) when compared to the same type of biocidal coating but with a smooth finish (Rt(50) = 43 μm). This paper demonstrates primarily how field-grown fouling affects the antifouling efficacy and drag performances of both biocidal and non-biocidal coatings. In addition, the paper also presents a correlation of drag and surface characteristics using a new scaling based on fouling pattern, fouling % cover and surface free energy.

Nanoscale electropolishing of high-purity nickel with an ionic liquid

High purity (>99.9% composition) nickel metal specimens were used in electropolishing treatments with an acid-free ionic liquid electrolyte prepared from quaternary ammonium salts as a green polishing solution. Voltammetry and chronoamperometry tests were conducted to determine the optimum conditions for electrochemical polishing. Atomic force microscopy (AFM) revealed nanoscale effectiveness of each polishing treatment. Atomic force microscopy provided an overall observation of the material interface between the treated and unpolished regions. Surface morphology comparisons summarized electrochemical polishing efficiency by providing root-mean-square roughness averages before and after electrochemical polishing to reveal a mirror finish six times smoother than the same nickel metal surface prior to electropolishing. This transition manifested in a marked change in root-mean-squared roughness from 112.58 nm to 18.64 nm and producing a smooth mirror finish. Finally, the mechanism of the ionic liquid during electropolishing revealed decomposition of choline in the form of a transient choline radical by acceptance of an electron from the nickel-working electrode to decompose to trimethylamine and ethanol.

Controlling the Morphology of Organic-Inorganic Hybrid Perovskites through Dual Additive-Mediated Crystallization for Solar Cell Applications.

To realize a high-efficiency perovskite solar cell (PSC), it is critical to optimize the morphology of the perovskite film for a uniform and smooth finish with large grain size during film formation. Using a chemical compound as an additive to the precursor solution has recently been established as a promising method to control the morphology of the perovskite film. In this study, we propose a new method to achieve an improved morphology of the methylammonium lead iodide perovskite film by simultaneous addition of dimethyl sulfoxide (DMSO) and methoxyammonium salt (MeO) (dual additives). We demonstrated that an appropriate amount of the MeO additive helps the precursors form a stable intermediated PbI2-DMSO adduct during film formation and enlarges the perovskite grains by retarding the kinetics of conversion of the adduct to the perovskite. Furthermore, we experimentally observed that the optical band gaps and crystal structures of perovskite films are reasonably unaffected by the MeO additive because MeO is almost eliminated during annealing. By optimizing the amount of MeO, we achieved improved device performances of the PSCs with a high power conversion efficiency of 19.71% that is ∼15% higher than that obtained for the control device (17.15%).

Admixtures Used in Self-Compacting Concrete: A Review

Self-compacting concrete or self-consolidated concrete is a highly flowable, non-segregating concrete which spreads into congested reinforcement area and fills the formwork without the use of any vibrators. Self-compacting concrete allows denser reinforcement, optimized concrete section and shapes, and greater degree of freedom. It has the advantages of maintaining the durability and characteristics and meeting expected performance requirements. It has been used ideally in bridges, drilled shaft, and earth-retaining structure, columns and area with high concentration of rebars and pipes. The self-compacting concrete improves constructability, reduces skilled labor and noise level, minimizes the voids in highly reinforced area, gives superior strength and durability and smooth and uniform surface finishing and accelerates the project schedules. In the present study, various mineral admixtures, i.e., ground-granulated blast-furnace slag, limestone powder, silica fume, fly ash and chemical admixtures such as sulfonated melamine formaldehyde condensate, melamine formaldehyde, sulfonated naphthalene formaldehyde condensates and polycarboxylate ether-based superplasticizer, have been studied in the self-compacting concrete. A critical review of the effect of combination of these mineral and chemical admixtures on various rheological, strength and durability properties of the self-compacting concrete is presented in this paper.

Formation of SS316L Single Tracks in Micro Selective Laser Melting: Surface, Geometry, and Defects

To fabricate complex parts with a fine resolution and smooth finish, micro selective laser melting (SLM) has been developed recently by combining three attributes: small laser beam spot, fine powder size, and thin layer thickness. This paper studies the effect of the micro-SLM process parameters on the single track formation of 316L stainless steel. The surface morphology, geometrical features, and defects have been analyzed in detail. The results highlight that laser power and scanning velocity have a significant effect on the formation of single tracks. The single tracks fabricated through micro-SLM with varying process parameters are classified into four types: no melting, discontinuous, continuous but unstable, and continuous tracks. Besides, the top surface of the tracks is observed with “double-crest” morphology, due to the high recoil pressure gradient generated by the extremely fine spot size. In addition, molten pool geometry (width, depth, and height) has been characterized to study the mode of the molten pool in micro-SLM. Finally, the occurrence of two typical defects within the tracks, keyhole pore and cavity at the edges, has been studied.

The Corrosion Behavior of Anti-Graffiti Polyurethane Powder Coatings

Anti-graffiti coatings have become more important. These layers must guarantee excellent corrosion protection properties, and graffiti must be easily removable, without reducing protection and aesthetic properties. In this study, anti-graffiti and corrosion behavior of two anti-graffiti polyurethane powder coatings were studied. These layers were deposited on aluminum substrate, with two different surface finishes, smooth, and wrinkled. The action of four different removers are investigated. Graffiti were drawn on coatings by means of red acrylic spray paint. Methyl-ethyl-ketone (MEK) and a “commercial” remover were the most effective solvents, in terms of graffiti removal capability, producing limited change in aesthetical surface aspect for smooth finishing. The wrinkled surface was less resistant. Corrosion protection properties, after removal action and contact with the remover, were evaluate by electrochemical impedance spectroscopy. After approximately 5 hours, coatings were no longer protective due to formation of defects. To simulate the weathering effect, UV-B cyclic test (4 hours of UV exposure followed by 4 hours of saturated humidity at 50 °C) were performed for 2000 hours. Gloss and color changes were measured, and electrochemical impedance spectroscopy measurements were performed after aging and graffiti removal.

Diffusion behavior of Cr in gradient nanolaminated surface layer on an interstitial-free steel

Nanolaminated structures composed of low-angle grain boundaries (LAGBs) possess high thermal stability. In this paper, a gradient nanolaminated (GNL) surface layer with smooth finish was fabricated on an interstitial-free steel by means of surface mechanical rolling treatment. Microstructural observations demonstrated that the average lamellar thickness is about 80 nm in the topmost surface layer and increases with increasing depth. High thermal stability was confirmed in the GNL surface layer after annealing at 500 °C. Diffusion measurements showed that effective diffusivity of Cr in GNL layer is 4–6 orders of magnitude higher than lattice diffusivity within the temperature range from 400 to 500 °C. This might be attributed to numerous LAGBs or dislocation structures with a higher energy state in the GNL surface layer. This work demonstrates the possibility to advanced chromizing (or other surface alloying) processes of steels with formation of GNL surface layer, so that a thicker alloyed surface layer with a stable nanostructure is achieved.

Improvement acoustic quality room live music P-Two cafe Surabaya

Music room needs good sound clarity to make the intonation tone can be delivered clearly. Room acoustic parameter which used are Reverberation Time, Clarity (C50), and Clarity (C80). The object of this research is P-Two cafe Surabaya. The purpose of this research is to redesign P-Two cafe room and to make an appropriate room for live music according to the international standard. The design is done by giving insulators and absorbers to the room. Method of interpretation data is Impulse Response. Besides, simulation from calculated results done by using EASE 4.3. The result of calculated sound pressure level has been able to reduce the sound pressure level for about 42 dB for wall which is made by glass. The simulation result of alternative redesign which used gypsum board material, wood floor carpet, concrete smooth finish and wood surface showed 1,43 second for room RT the result before are 0,6 second smaller. Simulation result of Clarity (C50) is -1 and Clarity (C80) is 1,67 that also showed the room is according to the standard which means the speech and live music of room are getting better.

A 3D Printed Linear Pneumatic Actuator for Position, Force and Impedance Control

Although 3D printing has the potential to provide greater customization and to reduce the costs of creating actuators for industrial applications, the 3D printing of actuators is still a relatively new concept. We have developed a pneumatic actuator with 3D-printed parts and placed sensors for position and force control. So far, 3D printing has been used to create pneumatic actuators of the bellows type, thus having a limited travel distance, utilizing low pressures for actuation and being capable of only limited force production and response rates. In contrast, our actuator is linear with a large travel distance and operating at a relatively higher pressure, thus providing great forces and response rates, and this the main novelty of the work. We demonstrate solutions to key challenges that arise during the design and fabrication of 3D-printed linear actuators. These include: (1) the strategic use of metallic parts in high stress areas (i.e., the piston rod); (2) post-processing of the inner surface of the cylinder for smooth finish; (3) piston head design and seal placement for strong and leak-proof action; and (4) sensor choice and placement for position and force control. A permanent magnet placed in the piston head is detected using Hall effect sensors placed along the length of the cylinder to measure the position, and pressure sensors placed at the supply ports were used for force measurement. We demonstrate the actuator performing position, force and impedance control. Our work has the potential to open new avenues for creating less expensive, customizable and capable actuators for industrial and other applications.

Estimation of Zwitterionic Surfactant Response in Electroless Composite Coating and Properties of Ni–P–CuO (Nano)Coating

Electroless Ni–P and Ni–P–CuO coating on mild steel was developed successfully with the addition of Zwitterionic surfactant. The usage of nano-CuO in electroless coating was intermittent though the cost is low with high catalytic activity. Zwitterionic surfactant was introduced into the composite coating for the first time to increase the suspension of nanoparticles effectively during the coating process. Surfactant helps to reduce the intermolecular attraction between the solid and liquid interfaces and hence binding of nanoparticles with the hydrogen gas bubbles was eliminated. Also agglomeration of nanoparticles was controlled by stirring the electrolyte continuously using magnetic stirrer. The characterization and tribological properties were tested for the newly developed composites. Scanning electron microscope micrograph reveals the deposits are produced without any defects and the presence of CuO nanoparticles in the deposit. Energy-dispersive spectroscopy measurement shows the changes of weight percentage of elements available in the substrate. The surface roughness of the deposit was improved with the addition of CuO, it packs the gap between two grains and offers smooth finish and as the result the surface properties are modified. Microhardness of the substrate was improved for the substrate added with nano-CuO. The corrosion resistance of the substrate was improved when compared to the substrate produced using electroless Ni–P binary coating. Zwitterionic surfactant reduces the agglomeration of nanoparticles during chemical reaction and allows the particles to coat only on the target. Similarly, this technique can be implemented in the production of other composites in electroless coatings.

Use of Cement Stabilized Rammed Earth for Load Bearing Wall with Appropriate Finishes-Case Study

Rammed earth is one of the traditional technology used for putting up houses in most parts of the world and it is being now rapidly developed through researches due to its valuable qualities especially strength, durability, environmental friendly and affordability. As a result, cement has been introduced as a stabilizer to gain high strength and durability. Local building codes and guidelines have been established to design and construct rammed earth walls successfully in buildings. Aim of this paper is to demonstrate the application of cement stabilized rammed earth for making load bearing walls of two storey house combining with reinforced cement concrete beams, lintels, slab and stairway. These walls have been structurally designed by following the code of engineering design of earth buildings NZS 4297:1998 published by New Zealand and applying strength parameters derived for local soils. House construction was totally completed in 2015 with smooth and rough wall finishes for internal and external surfaces of walls to get the good appearance to the house.

Masquelet technique: The effect of altering implant material and topography on membrane matrix composition, mechanical and barrier properties in a rat defect model

The Masquelet technique is a surgical procedure to regenerate segmental bone defects. The two-phase treatment relies on the production of a vascularized foreign-body membrane to support bone grafts over three times larger than the traditional maximum. Historically, the procedure has always utilized a bone cement spacer to evoke membrane production. However, membrane formation can easily be effected by implant surface properties such as material and topology. This study sought to determine if the membrane’s mechanical or barrier properties are affected by changing the spacer material to titanium or roughening the surface finish. Ten-week-old, male Sprague Dawley rats were given an externally stabilized, 6 mm femur defect which was filled with a pre-made spacer of bone cement (PMMA) or titanium (TI) with a smooth (∼1 μm) or roughened (∼8 μm) finish. After 4 weeks of implantation, the membranes were harvested, and the matrix composition, tensile mechanics, shrinkage, and barrier function was assessed. Roughening the spacers resulted in significantly more compliant membranes. TI spacers created membranes that inhibited solute transport more. There were no differences between groups in collagen or elastin distribution. This suggests that different membrane characteristics can be created by altering the spacer surface properties. Surgeons may unknowingly effecting membrane formation via bone cement preparation techniques.

Micro-beam plasma polishing of ground alloy steel surfaces

Polishing provides a commendable approach to gain high quality surfaces after machining or forming processes. A micro-beam plasma polishing was presented in this paper. Several metal materials were tested and SUS304 was used to find optimized parameters. A numerical simulation model was established on COMSOL software to help digest melt pool dynamics which influences roughness a lot. The experiment showed a reduction of roughness from Ra=4.07μm to Ra=0.46μm with optimized parameters. The simulation proved that the increase in electric current can increase melt pool velocity, which is in favor of obtaining a smooth finish surface.

Analysis of Process Parameters in Surface Grinding Process

Surface grinding is a familiar method used in the division of manufacturing in order to generate smooth finish on flat surface. Surface finish and metal removal rate are the two major characteristics to be considered in the grinding process. In this paper, Taguchi method L18-OA of design of experiments is used to analyse the grinding process parameters such as grinding wheel speed, table speed & depth of cut in order to get superior surface finish. The depth of cut, table speed and wheel speed are used to find dominant factor affecting surface finish and metal removal rate of the grinding process.

Atomic-scale finishing of carbon face of single crystal SiC by combination of thermal oxidation pretreatment and slurry polishing

Single-crystal silicon carbide (4H-SiC) has a range of useful physical, mechanical and electronic properties that make it a promising material for fabrication of next-generation semiconductor devices. In this work, we report a hybrid polishing process combining thermal oxidation pretreatment and soft abrasive polishing to realize the damage-free and atomic-scale smooth finishing of the carbon face of 4H-SiC. By thermal oxidation pretreatment, the hardness of the carbon face has been reduced from 4.6GPa to 1.7GPa, which enables highly efficient polishing using CeO2 slurry. For conventional CeO2 slurry polishing without pretreatment, scratches still existed after a long polishing duration for 16h. The probable scratch removal mechanism in CeO2 slurry polishing has been proposed based on surface morphology changes during polishing. Whereas a scratch-free surface with well-ordered SiC atomic steps was obtained within a short polishing duration of only 3h when polishing was conducted on a thermally oxidized surface. Our results demonstrate that hybrid polishing combining surface pretreatment and soft abrasive polishing is a promising approach to realize the damage-free and atomic-scale smooth finishing of the carbon face of 4H-SiC.

Study the Effect of SiO2 Based Flux on Dilution in Submerged Arc Welding

This paper highlights the method for prediction of dilution in submerged arc welding (SAW). The most important factors of weld bead geometry are governed by the weld dilution which controls the chemical and mechanical properties. Submerged arc welding process is used generally due to its very easy control of process variables, good penetration, high weld quality, and smooth finish. Machining parameters, with suitable weld quality can be achieved with the different composition of the flux in the weld. In the present study Si02-Al2O3-CaO flux system was used. In SiO2 based flux NiO, MnO, MgO were mixed in various proportions. The paper investigates the relationship between the process parameters like voltage, % of flux constituents and dilution with the help of Taguchi’s method. The experiments were designed according to Taguchi L9 orthogonal array, while varying the voltage at two different levels in addition to alloying elements. Then the optimal results conditions were verified by confirmatory experiments.

Effect of impact assembly on the interface deformation and fretting corrosion of modular hip tapers: An in vitro study.

Wear and corrosion at the modular head-neck junction has been recognised to be a potential clinical concern, with multiple reports on adverse local tissue reactions and subsequent early failure of metal-on-metal hip replacements. Furthermore, reports on head-neck taper corrosion are also being described with conventional metal-on-polyethylene bearings. Manufacturing tolerances, surgical technique, non-axial alignment, material combination, high frictional torque and high bending moment have all been implicated in the failure process. There is limited guidance on the force of impaction with which surgeons should assemble modular hip prostheses. This study aims to investigate the effect of impaction force on the deformation and corrosion of modular tapers. Short neck tapers with high surface roughness (average Rz = 16.58 μm, Ra = 4.14μm) and long neck tapers with low surface roughness (average Rz = 3.82 μm, Ra = 0.81μm), were assembled with CoCrMo alloy heads (smooth finish) under controlled conditions with 2, 4 or 8 kN of impaction force. Material combinations tested included CoCrMo-head/CoCrMo-neck and CoCrMo-head/Ti-6Al-4V-neck. Assessment of surface deformation before and after impaction was made using surface profilometry. Measurement of fretting current during sinusoidal cyclic loading evaluated mechanically assisted corrosion for each assembly load during short-term cyclic loading (1000-cycles) and long-term cyclic loading (5 million-cycles). Deformation on head and neck tapers increased with assembly load. Fretting currents during short term simulation testing showed significantly lower currents (p < 0.05), in 8 kN assemblies when compared to 2 and 4 kN, especially for the short-rough tapers. Long-term simulator testing demonstrated a progressive reduction in fretting corrosion for samples impacted with 4 and 8 kN; however, this reduction was greater for samples impacted at 8 kN even at the start of testing. Based on our results, surgeons could minimise mechanically assisted crevice corrosion by using higher impact loads when assembling the head to the stem in total hip arthroplasty. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:405-416, 2018.

Gait of dairy cows on floors with different slipperiness.

This study assessed the slip resistance of different types of solid flooring in cattle housing using a range of technical tests and gait analysis. Dynamic and static coefficient of friction, skid resistance, and abrasiveness were tested on concrete flooring with a smooth finish, a grooved pattern, or a tamped pattern, acid-resistant mastic asphalt, soft rubber mats, and a worn slatted concrete floor. Coefficients of friction and skid resistance were tested under clean and slurry-soiled conditions. Linear kinematic variables were assessed in 40 cows with trackway measurements after the cows passed over the floors in a straight walk. All gait variables were assessed as deviations from those obtained on the slatted concrete floor, which was used as a baseline. The coefficient of friction tests divided the floors into 3 categories: concrete flooring, which had a low coefficient of friction (0.29-0.41); mastic asphalt flooring, which had medium values (0.38-0.45); and rubber mats, which had high values (0.49-0.57). The highest abrasion (g/10 m) was on the asphalt flooring (4.48), and the concrete flooring with a tamped pattern had significantly higher abrasiveness (2.77) than the other concrete floors (1.26-1.60). Lowest values on the skid-resistance tests (dry/wet) were for smooth concrete (79/35) and mastic asphalt (65/47), especially with a slurry layer on the surface. Gait analysis mainly differentiated floors with higher friction and abrasion by longer strides and better tracking. Step asymmetry was lower on floors with high skid-resistance values. The most secure cow gait, in almost every aspect, was observed on soft rubber mats. Relationships between gait variables and physical floor characteristics ranged from average to weak (partial correlations 0.54-0.16). Thus, none of the physical characteristics alone was informative enough to characterize slip resistance. With reference to gait analysis, the abrasiveness of the hard surfaces was more informative than the coefficient of friction, but the effect of pattern was better detected by skid-resistance measurements. Consequently, several physical characteristics are needed to objectively describe the slip resistance of cattle floors. Soft rubber mats gave better tracking than hard, solid floors, even with a grooved surface or a tamped pattern.

Highlighting the Build: Using Lighting to Showcase the Sydney Opera House

Highlighting the Build: Using Lighting to Showcase the Sydney Opera House

A facile technique for fabricating poly (2-methacryloyloxyethyl phosphorylcholine) coatings on titanium alloys

Poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC) has been widely used for surface modification of titanium (Ti) alloys to improve antifouling properties and blood compatibility. To achieve antifouling and anticoagulant capacities via a facile and efficient technique, PMPC coatings were covalently immobilized on a Ti surface simply by a sequential dip-coating method. The Ti surface was first dipped into hydrochloric acid (HCl) solution to remove surface contaminants and acquire a hydroxyl-enriched surface. Then, the surface was dipped into dopamine solution to acquire the surface bearing –NH2 groups. N-acryloxysuccinimide solution was used for introduction of double linkage which could graft with PMPC via in situ free-radical polymerization. Thus, the surface modification processes were under mild conditions and easy scale up. The obtained PMPC coatings endowed the Ti surface with smooth finish and relatively high packing density. Water contact angle measurements showed that the hydrophilicity of the Ti surface was markedly improved by coating PMPC with the water contact angle of 6.2°. Furthermore, the PMPC coatings could effectively resist protein adsorption and suppress platelet adhesion and activation. The facile and efficient method of immobilization of PMPC on a Ti surface could be promising for a variety of cardiovascular applications.