Emery Paper Research Articles

A Cost-effective Method to Fabricate a Super-non-wetting Self-cleaning Transparent Emulsion Paint Coating

The procedure to fabricate an industrially-producible, practically-applicable and easily-reconstructible transparent paint coating with luminescence is introduced step- -by-step in this paper. Without chemical modification, an ultrahydrophobic transparent paint coating with luminescence can be readily created using cost-effective commercially available materials. Grinding the ultrahydrophobic transparent paint coating surfaces using appropriate emery papers can generate appropriate surface roughness and thereby endows the coating surfaces with super-non-wettability and self-cleaning property. The applications of the coating to the external walls of buildings can provide the walls with self-cleaning property, decorate the walls and save outdoor illumination power during the night.

EFFECTS OF WC, SiC, IRON AND GLASS FILLERS AND THEIR HIGH PERCENTAGE CONTENT ON ADHESIVE BOND STRENGTH OF AN ALUMINIUM ALLOY BUTT JOINT: AN EXPERIMENTAL STUDY

Improving of epoxy adhesive tensile joint strength is a major interest relevant to many industries. In this study, four types of fillers were chosen (tungsten carbide, silicon carbide, iron, and glass). Fillers were in the form of powder with a particle size of 140 μm. Adherents were 6061-T6 aluminium alloys fabricated according to ASTM D 2094-00 (2014). Bonding surfaces were prepared by grinding using 400 grit emery paper. The surfaces were then chemically etched using CSA solution. Two distance copper wires were used per specimen having a diameter of 180 μm. Five replicas per adhesive condition were adopted. Four volume filler fractions were chosen (10%, 15%, 20%, and 25%). A comparison of average tensile adhesive joint strength was made between the reference (no filler specimen) and other fillers. It was concluded that SiC and iron fillers had negative results on the joint strength, with the worse results occurring at high fractions. Glass with low fractions slightly enhanced the joint strength but showed negative results when the volume fraction was increased. Tungsten carbide showed a slight improvement at 10% fraction, but a major improvement was achieved. In particular, at 20% fraction the strength was enhanced by 41.33%.

Abrasive wear behaviour of SBR/HIPS (%35–55) polymer blends

Styrene Butadiene Rubber (SBR), being the most widely produced synthetic rubber, is a random copolymer of styrene and butadiene. The physical properties of SBR are related to the amount of styrene in copolymer chains and styrene/butadiene ratios in the copolymer. SBR is used in many areas such as tires, conveyor belts, mats, shoe soles, and heels, while Polystyrene, due to its brittle nature, its usage is limited. This study examines the abrasive wear behavior of SBR and High-Impact Polystyrene (HIP) polymer blends. For the experiments, SBR /HIPS polymer blends were prepared by adding HIPS at different ratios (35%–55%) to SBR. Using emery paper of 240 G and 500 G, wear tests were carried out on a pin-on disc wear test apparatus under the load value of 5 N, for sliding distances ranging from 25 to 100 m and at a sliding speed of 1 m s−1. Density and hardness measurements of the samples were carried out. The worn surfaces of the pin were examined using an optical microscope. It is clearly shown that the wear coefficients of polymer blends are dependent on both abrasive nature and the ratio of blends.

Ni-Fe Hydroxide/Oxide Nanostructures Generated on Stainless Steels for Efficient Alkaline Water Electrolysis

Introduction Developing highly active and durable electrocatalysts for oxygen evolution reaction (OER) have been needed for efficient hydrogen generation by electrochemical water splitting. Although various transition metal-based oxides, hydroxides, selenides etc. have been extensively explored as OER catalysts for alkaline water electrolyzer (AWE) (1, 2), detachments of the effective materials for the OER are serious issues from the electrode surface by vigorous oxygen gas evolution under the practical condition (3). Stainless steels (SS) have much attractive attentions as low-cost, highly active and stable electrode materials at high current density (4). However, relation between nano-level structures of the surface oxide layers on the SS substrate and OER properties should be clarified. In this study, we investigated changes in OER properties and nanostructures of the surface oxide layers generated on the 316SS electrode during the electrolysis. Experimental 316SS (ø = 5mm, t = 4mm) substrate was used as a working electrode after the surface polishing by Emery papers (#800, #1200, #2000) and alumina paste (1 μm, 0.3 μm, 0.05 μm). Polarization curves for the OER with a disk rotation rate of 1600 rpm were measured in N­2-purged 1 M KOH solution at 75 ℃ at 5 mV/sec. Cyclic voltammograms were collected at 50 mV/sec without disk rotation. After that, constant current density electrolysis (CCE) was conducted at 30 mA/cm2 for 10 h at 1600 rpm. Nanostructures and compositions of the surface oxide layers generated after the electrolysis were investigated by scanning transmission electron microscopy (STEM) with electron dispersive spectroscopy (EDS). Results and Discussions Fig.1 (a) shows changes in the OER overpotentials estimated by the polarization curves at 10 (red) and 100 (blue) mA/cm2 as a function of the CCE times. The overpotentials decreased with increasing the CCE times. In addition, as shown in (b), the cyclic voltammograms indicate the Ni-oxidation peaks of the CCE-5h sample (red) shift to lower potential compared with the pristine substrate(CCE-0h), suggesting the electrochemical property of the SS substrate surface changed during the electrolysis. STEM images of the CCE-5h sample with different magnifications are presented in (c). The surface oxide layers are composed of 20nm-thick dense nanoporous-like (substrate side)and 60nm-thick nanofiber-like layers. The selected area electron diffraction (SAED) patterns suggests that crystal structures of each oxide layers are rock-salt NiO and β-Ni(OH)2, respectively. Furthermore, corresponding STEM-EDS mappings (d) reveals that Fe and Ni are only metal elements and Cr is almost absent in both the oxide layers. Therefore, increase in OER activity during the CCE probably stems from generation of the specific Ni-Fe hydroxide nanostructures that acting as highly-OER-active sites (5). The results in this study clearly show that electrochemical synthesis of such the hetero-structured hydroxide/oxide layers on the SS substrate is an effective approach for developments of the practical anode for AWE. Acknowledgments This study was partly supported by JSPS KAKENHI Grant Number 18H01741, Toyota Mobility Foundation Hydrogen Initiative, and Yazaki Memorial Foundation for Science and Technology (N.T.). References N.-T. Suen, S.-F. Hung, Q. Quan, N. Zhang, Y.-J. Xu and H. M. Chen, Chem. Soc. Rev., 46, 337 (2017).S. Anantharaj, S. R. Ede, K. Sakthikumar, K. Karthick, S. Mishra and S. Kundu, ACS Catal., 6, 8069 (2016).C. Spöri, J. T. H. Kwan, A. Bonakdarpour, D. P. Wilkinson and P. Strasser, Angew. Chem. Int. Ed., 56, 5994 (2017).H. Schäfer and M. Chatenet, ACS Energy Lett., 3, 574 (2018).D. Friebel, M. W. Louie, M. Bajdich, K. E. Sanwald, Y. Cai, A. M. Wise, M.-J. Cheng, D. Sokaras, T.-C. Weng, R. Alonso-Mori, R. C. Davis, J. R. Bargar, J. K. Nørskov, A. Nilsson and A. T. Bell, J. Am. Chem. Soc., 137, 1305 (2015). Figure 1

Hydrogen charging of Al–Mg–Si-based alloys by friction in water and its effect on tensile properties

In order to introduce high amounts of hydrogen into aluminum alloys, hydrogen charging in peak-aged Al–Mg–Si-based alloys (A6061-T6) by means of friction in water (FW) was investigated and the hydrogen embrittlement (HE) sensitivity of the samples was evaluated. Al–Mg–Si alloys containing different amounts of iron (from 0.1 to 0.7 mass %) were prepared in order to clarify the effect of iron on the HE sensitivity. Hydrogen charging was carried out by polishing the alloy surface for 1 h with a silicon carbide emery paper in water at room temperature. For comparison, hydrogen-uncharged alloy specimens were also prepared. The total amount of hydrogen in the Al–Mg–Si alloys clearly increased after the FW process, during which hydrogen was generated by the chemical reaction between water and the non-oxide coated aluminum alloys. After hydrogen charging by the FW process, the Al–Mg–Si alloy with a low iron content (0.1 mass %) showed a decrease in ductility in conventional strain rate tensile testing; conversely, alloys with higher iron contents (0.2 and 0.7 mass %) did not show a decrease in ductility. This suggests that peak-aged Al–Mg–Si alloys with high iron contents are less sensitive to HE.

Silicon Carbide Ceramic Particulate Reinforced AA2024 Alloy Composite - Part I: Evaluation of Mechanical and Sliding Tribology Performance

In this research work, a master batch (comprising of AA2024 alloy, Silicon Nitride (Si3N4) and Graphite particulates) was reinforced by Silicon-Carbide (SiC) ceramic particulates (0–6 wt.-%; at steps of 2%; i.e. four composites samples viz. ASC-0; ASC-2; ASC-4; ASC-6) with the aim of enhancing mechanical and sliding tribology performance. The semi-automatic stir-casting fabrication process was followed as per standard industrial practice in-order-to fabricate the sample plates of the said alloy composites as per design. Thereafter, the sample specimens were prepared via wire EDM cutting followed by polishing over emery paper; as per ASTM standard dimensions and various physical (density and void content), mechanical (tensile strength, flexural strength, impact strength, hardness etc.), sliding tribology performance (steady state sliding wear; ASTM G-99; Pin-on-Disc tribo-meter), thermal (thermal conductivity, Thermo-Gravimetric Analysis (TGA)); thermo-mechanical (Dynamic Mechanical Analysis (DMA)), fracture-analysis, X-ray diffraction (XRD) etc. characterisation were performed and discussed. In Part-1: Physical, mechanical and sliding tribology performances were discussed. The Taguchi design of experiment technique was employed for designing of experimental runs having input controlling parameters like sliding velocity (0.654–2.616 m/s), sliding distance (784.8–3139.2 m), normal load (5–50 N), reinforcement content (0–6 wt.-%) and environment temperature (20–50 °C). The worn surface morphology studies were performed to understand prevalent wear mechanism using Field Emission Scanning Electron Microscope (FESEM) along with Energy-dispersive X-ray spectroscopy (EDS) that reveals elemental composition and its dispersion on the surface. In Part-2: evaluation of characterizations like thermal, thermo-mechanical, fracture-analysis, X-ray diffraction (XRD) etc. were discussed in correlation with mechanical and sliding wear performance. In Part-3: the entire performance data are analysed using hybrid AHP-TOPSIS technique (an MCDM technique; computationally simple and easy to understand) in-order-to rank the composites formulations.

Effect of Soil Particle Size on Corrosion Behavior of Buried Carbon Steel

Introduction The fundamental cause of the deterioration of buried steel structures is soil corrosion. Soil corrosion is a complicated phenomenon because various environmental factors are related to each other. Additionally, due to the complexity of soil and its pores constituted by a solid phase, water liquid phase, and air and gas phases, the soil corrosion mechanism is still unclear. In spite of the inherent complexity of the soil environment, corrosion of carbon steel in soil is considered to be similar to that in a neutral solution. That is, soil corrosion is considered to be promoted by water and dissolved oxygen (DO) in soil water. With this nature of soil corrosion, environmental factors in soil can be represented as two principal ones: soil particle size, which influences the state of water in the soil and DO diffusion behavior, and soil water content. In this study, we evaluated the effects of soil particle size and water content on the corrosion rate of buried carbon steel by electrochemical impedance spectroscopy in a simulated soil environment. Experimental Carbon steel with an exposed electrode area of 10 × 10 mm was polished with #800 emery paper. The soil samples used for the experiment were prepared from reddish gardening soil, which was sifted with sieves into coarse- (0.5­­­­–2 mm) and fine- (<0.5 mm) grains. By mixing the coarse grains with the fine grains, the soil samples were classified into three levels coarse: fine = 1:0, 1:1, and 0:1. The soil was placed in a glass container and the electrode was buried in the soil. At the beginning of the experiment, enough water was supplied so that the soil was immersed. Water was gradually drained with time through a filter installed on the bottom of the container. The AC impedance measurements were carried out at constant time intervals. In the test chamber, the temperature was held constant at 25ºC with relative humidity of 60%. Results and discussion Figure 1 shows Nyquist plots obtained from the AC impedance measurement of carbon steel in the coarse: fine = 1:0 soil with water content of 43%. The equivalent circuit is also shown, where Rs is the solution resistance, Cs is the soil capacitance, Rct is the charge transfer resistance, and Cdl is the electric double-layer capacitance. As shown in Fig. 1, capacitive loops appeared in the high- and low-frequency regions. In the Nyquist plots, the low-frequency represents Rct. Figure 2 shows change in reciprocal Rct, calculated at each water content while water content was decreased. The horizontal axis is water content and the vertical axis is 1/Rct, which is directly proportional to the corrosion rate. The 1/Rct showed a maximum peak at a certain water content in all soil samples, and that water content showed smaller values as the particle size was smaller. Further, the maximum corrosion rate increased with decreasing particle size. It is considered that the maximum corrosion rate appears when the condition that the water film is thin and the effective wet area is large. As the particle size decreases, the pressure applied to capillary water becomes stronger. So, the effective wet area doesn’t decrease and thinner water film is formed. Accordingly, the water content satisfying the above condition becomes low, and the maximum corrosion rate increases. Conclusion The effects of soil particle size and soil water content on the corrosion rate of buried carbon steel were evaluated by the AC impedance technique. The maximum corrosion rate appeared at a certain water content, which varied depending on the soil particle size. The measured trends were rationally interpreted in terms of the balance between the effective wet area of the steel surface and the DO diffusion path distance depending on soil particle size and water content. Figure 1

Experimental investigation of mechanical properties of epoxy based composites

In this study, the investigation of mechanical properties of epoxy based composites was conducted experimentally. The matrix material used in the research work was epoxy resin and jute and basalt fibre were used as the reinforcement material for the preparation of the hybrid composite. Each hybrid composite consists of eight stack of layers of fibres oriented accordingly to achieve high strength. Tensile test, compressive test and wear test were performed to investigate the mechanical properties and machinability of the composite material. Tests were carried out according to the ASTM standards. Tensile test and compressive test were performed in universal testing machine and wear test was performed on pin-on-disc wear testing machine. Each hybrid composite consists of eight stacks of layers of fibres oriented accordingly to achieve high strength. It was observed that the tensile modulus of the epoxy based hybrid composite increases with increase of layers of basalt fibre. It was observed that the compressive modulus and compressive strength also increase rapidly. Silicon carbide emery paper was used for the testing of abrasive wear rate of the specimen. Taguchi technique was used to optimize the parameters and the input parameters used in the wear analysis includes; the type of the specimen, load and density. Specific wear rate for each specimen was calculated and the main effects plots for signal-to-noise ratio were drawn and analyzed in this research work.

Effect of topspin on the apparent speed of a tennis court

Experimental results are presented concerning the impact of a tennis ball incident obliquely with topspin on a rigid, horizontal surface. The ball was launched at speeds between 12 and 17 m/s onto P800 emery paper attached to a heavy block of granite. The angle of incidence to the surface was varied from $$14^{\circ }$$ to $$65^{\circ }$$ and the spin of the ball was varied from 0 to 360 rad/s to examine the effects on the horizontal rebound speed. The ratio of the rebound to the incident horizontal speed increased from 0.5 to 0.95 as the incident spin was increased. The classification or perception of a tennis court as being fast or slow is therefore of limited value, given that most players strike the ball with topspin.

Abrasive Wear Characteristics of Composite Material (AA 7075 / SiC) Synthesized by Stir Casting

Aluminum Metal Matrix Composites (ALMMCs) was prepared by using stir casting technique for AA 7075 aluminum alloy as a matrix reinforced with SiC particles at various percentages (3, 6, 9 and 12 wt. % ) and 75µm in grain size. The prepared composite material can be used for many applications such as aerospace, automobiles and many industrial sectors. Abrasive wear test was carried out by two stages: the first stage was done by changing the emery papers at various grit sizes 180, 320, 500, and 1000µm with constant applied load 15N. While the second stage was carried out by changing the applied loads 5, 10, 15, 20 and 25N with constant emery paper at 320 µm grit size. Microstructure examination, hardness test and roughness test were performed before and after abrasive wear test. The results of this investigation showed the increasing in weight percentage of the reinforcement material leads to increase the hardness, roughness and improving the abrasive wear resistance.&#x0D;

Mechanical and abrasive wear behavior of cenosphere filled carbon reinforced epoxy composites using Taguchi-Grey relational analysis

Carbon fabric reinforced Epoxy (C-E) composites filled with different weight percentage of silane treated flyash cenosphere (CSP) particles were synthesized using hand layup process followed by compression moulding method. The fabricated samples were subjected to mechanical tests and two body multipass abrasive wear test (2BMAW) in accordance with American society for testing and materials (ASTM). Mechanical results showed addition of CSP particles in C-E composites tends to improve property such as density, hardness, flexural and impact strength. Meanwhile Taguchi method with Grey relational analysis (GRA) was implemented for 2BMAW test to optimize the wear process parameters with multi-response characteristics. Filler wt% (Filler content), Grit size of abrasive (emery paper), sliding distance (m) and Load (N) were selected as wear process parameters for which responses were coefficient of friction (COF), specific wear rate (SWR) and hardness (BH) of the composites. Analysis of variance (ANOVA) result based on grey relational grade (GRG) revealed that filler wt% (filler content) and sliding distance were found as most significant process parameter influencing the wear performance of the composites by 55% and 19% respectively followed by Grit size of emery paper and applied load. Finally microstructure analysis of the fractured and worn sample has been studied using scanning electron microscope to understand the mode of failure mechanism.

Study of Corrosion Rate of Buried Steel in Soil By Electrochemical Impedance Spectroscopy

Introduction Buried steel structures generally deteriorate due to soil corrosion. The rate of the deterioration depends on soil environment factors such as the water content, temperature, pH value, resistivity, and oxygen concentration. Therefore, preventing the deterioration of buried steel structures or predicting their lifetime requires clarification of the quantitative relationship between these soil environment factors and the corrosion rate. However, it is difficult to determine the relationship because soil is a complex environment constituted by solid, liquid, and gas phases. Therefore, we are investigating the influence of the soil environment factors on the corrosion rate by using electrochemical measurements. In this study, we focused on the influence of soil water content on the corrosion rate of buried steel because it is one of the most important parameters in soil corrosion. According to our previous investigation, the soil water content is not constant and usually changes with precipitation. Here, we evaluated the corrosion rate of carbon steel buried in soil by electrochemical impedance spectroscopy in a simulated soil environment with changing water content. Experimental The electrode cell for the AC impedance measurements were fabricated from a carbon steel plate with dimensions of 10 × 10 mm and embedded in epoxy resin. The electrode was polished with #800 SiC emery paper. The soil used in this study was reddish gardening soil. The soil was sifted and then classified into several levels of particle size. The electrode cell and soil were placed in a glass container. At the beginning of the measurement, enough water was added to the container to thoroughly wet the soil, and the water content in the soil decreased with elapsed time. The surrounding temperature of the container was maintained at 298 K during measurements. The AC impedance measurements were carried out at constant time interval in order to evaluate the corrosion rate of the carbon steel with changing water content in the soil. Results and Discussion Figure 1 shows a Nyquist plot obtained from the AC impedance measurement of steel buried in the reddish soil with water content of 33.4%. The equivalent circuit is also shown, where Rs and Cs are the resistance and capacitance in soil, and Rct and Cdl are the charge transfer resistance and the double layer capacitance. As shown in Fig. 1, a capacitive loop appeared in the low-frequency region. The radius of this loop represents the charge transfer resistance Rct, which is inversely proportional to the corrosion rate. Therefore, the integration of the 1/Rct versus elapsed time curve provides the total amount of corrosion that occurred during the electrochemical measurement. The monitored water content in the soil and the 1/Rct values with elapsed time are shown in Fig. 2. The water content in soil gradually decreases with elapsed time. However, the change in the value of 1/Rct that is proportional to the corrosion rate was not monotonic. Figure 3 shows the dependence of the 1/Rct changes on the water content in soil. The value of 1/Rct showed a maximum peak at nearly 35% water content. This indicates that the corrosion rate and water content are not in a simple proportional relationship. It is considered that the water liquid and oxygen gas phases in soil are competing with each other. Then the corrosion rate shows the maximum peak when the proportions of these two phases are balanced. Conclusion Corrosion rate monitoring by electrochemical impedance spectroscopy was carried to reveal the quantitative relationship between the corrosion rate and the water content in soil. It was found that there is no proportional relationship between them, and the corrosion rate has the maximum value at a certain water content, which is determined by the balance between the water liquid and oxygen gas phases in soil. Figure 1

Effects of rolling friction on a spinning coin or disk

Experimental and theoretical results are presented concerning the motion of a spinning disk on a horizontal surface. The disk precesses about a vertical axis while falling either quickly or slowly onto the surface depending on the coefficient of rolling friction. The rate of fall also depends on the offset distance, in the rolling direction, between the centre of mass and the line of action of the normal reaction force. Euler’s angular momentum equations are solved to obtain estimates of both the coefficient of friction and the offset distance for a 50.6 mm diameter brass disk spinning on three different surfaces. The fall times varied from about 3 s on P800 emery paper to about 30 s on glass.

Evaluation of Surface Roughness of 316L Stainless Steel Substrate on Nanohydroxyapatite by Electrophoretic Deposition

The present work was designed on producing nanohydroxyapatite layers using electrophoretic deposition (EPD) on 316L stainless steel substrate. The EPD coatings were prepared by the deposition of hydroxyapatite (HA)-chitosan nanocomposites on different substrate roughness (polish surface, 220 grit SiC grind, and sand blast surfaces). Depositions were performed using the suspensions of HA nano particles (3 g/L) in the mixture of alcohol and distilled water (ethanol, 5 vol. %water and containing 0.5 g/L of chitosan dissolved in 1 vol.% acetic acid. Coatings were achieved on the cathode at constant voltage, time and temperature (90 V, 5 min and 40 °C respectively); the pH value was performed and fitted at 4. After deposition, the coated samples were dried at room temperature for 24 h. The surface topography of coatings was analyzed using atomic force microscopy (AFM). SEM was used to postulate both the surface and the cross section morphology of the coatings. The adhesion bonding between the deposited coatings and substrate were measured using tape tester to evaluate the adhesion bonding between the coating and substrate. The results showed the deposited coatings on sand blasted substrate has less porosity compared with the polish surface and 220 emery paper SiC grinding substrate respectively. The coating on the sand blasted substrate showed higher nanoroughness (122 nm), better adhesion bonding (removal area 15%) and higher thickness layer (12 µm) than that of the polish substrate and 220 emery paper SiC grinding substrate.

Study of a super-non-wetting self-cleaning solar reflective blue-grey paint coating with luminescence

A method for generating a solar reflective blue-grey paint coating with yellow-green luminescence that is cost-effective, industrially scalable, widely applicable, easily repairable, super-non-wetting, self-cleaning, and solar reflective, is introduced. The coating can be manufactured using as-received commercially available materials and following a simple industrial procedure. Grinding the coating surfaces using emery papers with appropriate grit numbers can readily yield appropriate surface roughness, generate suitable micro-grooves and expose micro- and nano-particles on the coating surfaces, thus endowing the coating surfaces with super-non-wettability and self-cleaning property. The surface free energy of the coating only depends on the dispersive component and both the Lewis acid component and the Lewis base component are 0mN/m. The solar reflective blue-grey coating with solar reflectance of 0.808 can yield a cooling effect of 22.6°C relative to a flat or low-sloped concrete roof on a typical clear summer sunny day. It emits yellow-green luminescence during the night, thus decorating the buildings to some extent when applied to the external walls of buildings. Although the super-non-wettability of the coating surfaces might be destroyed mainly by the periodic spraying of water (simulated by 400h of artificial accelerated weathering tests), the super-non-wettability and the self-cleaning property can be completely re-established after roughening the weathered coating surfaces using emery papers with appropriate grit numbers. In terms of optical properties, the solar reflective blue-grey coating with yellow-green luminescence has good resistance to artificial accelerated weathering.

A novel strategy for durable superhydrophobic coating on glass substrate via using silica chains to fix silica particles

The practical application of superhydrophobic coatings on glass is usually restricted by their poor wear resistance due to the insufficient adhesion. A double-silica-layered structure was proposed to reinforce the coating adhesion on glass substrate. The wettability, surface morphologies, and chemical composition were investigated by water contact angle measurement, scanning electron microscopy (SEM), and fourier transformed infrared (FTIR) spectroscopy. The prepared superhydrophobic coating displays a good wear-resistance by emery paper and sand abrasion, which also has excellent thermal stability and UV resistance. This strategy shows a bright future for durable superhydrophobic coating on glass.

High temperature wettability studies for development of unmatched glass-metal joints in solar receiver tube

Abstract This paper presents the high-temperature wettability studies carried out during glass-metal joining for parabolic trough solar receiver tube. The bonding characteristics of the glass and metal directly depend upon the wettablity measured in terms of (contact angle) the types of oxide formed at the metal surface and the microstructural changes during the fabrication process. In this research work three different substrate materials, namely, Austenitic Stainless Steel SS304, copper and low carbon steel (AISI 1018) were polished against different grades of emery paper in order to generate variations in their surface roughness. Borosilicate glass pallet was melted over these specimens and high-temperature wettablity (contact angle) of glass over candidate material substrate specimen was examined. X-ray diffraction was used to detect the types of oxide formed on the substrate during the wetability study. Microstructural and macroscopic examination of the substrates revealed the morphological changes on substrate surfaces at different length scales. The wettablity of borosilicate glass over Austenitic Stainless steel SS 304 substrate was better as compared to copper and low carbon steel substrates. In the case of low carbon steel, metal specimen got distorted at joining temperature because of poor thermal stability of low carbon steel and no bonding was observed.

Biomécanique des nerfs collatéraux digitaux – étude cadavérique

Injuries to digital collateral nerves after hand trauma are frequent and results from surgical treatment are poor. Characterization of mechanical behavior of healthy collateral nerves is necessary to produce numeric models and enhance the comprehension of nerve repair and regeneration process. There is no standard in the literature to characterize healthy nerve mechanics. The mechanical properties of the repaired nerve should be as similar as the healthy nerves, following the principles of mechanobiology. The aim of this study was to characterize the mechanical properties of human digital collateral nerves to look for a correlation with density as an intrinsic property of materials. 4 hands, 18 digital collateral nerves of 5 cm average length, were harvested and preserved by immersion in a NaCl 0.9 % solution to be tested. Each nerve was labelled to identify the corresponding finger during the tensile test. The nerves were positioned in a frame of emery paper, sutured and glued with ethyl-2-cyanoacrylate. Once positioned and aligned in the tensile test machine, Instron ® 3345 the tensile test was performed at speed of 6 mm min. During the test the nerve was continuously rehydrated with a NaCl 0.9 % solution. Density was measured using a Pycnometer and registered for each nerve. The test was recorded by a high-speed camera to identify the failure pattern according to wether the failure occurs in distal, middle and proximal area of the nerve. Finally, the diameter was measured using ImageJ software in a posterior image analysis. The results concern 3 thumbs, 2 index fingers, 6 middle fingers, 3 ring fingers and 4 pinky fingers There is no statistical significant difference between the studied variables among fingers. The failure pattern was distal in 72.22 %, middle 11.11 % and proximal in 16.67 % of the cases in contrast to the results presented by Goldberg et al. [Goldberg SH et al., 2007]. Our study presented a specific modulus characterization of human digital collateral nerves, we do not found other studies to compare our results. A pattern for each finger can be expected, but due to the scanty number of probes patterns do not emerge. We presented the human digital collateral nerve specific modulus constituted of 18 nerves. The failure pattern was distal in 70 % cases. Further studies in nerve composition must be conducted to enhance the knowledge of nerve biomechanical behaviour.

CATHODIC HYDROGEN EVOLUTION ON COBALT MONOSILICIDE IN POTASSIUM HYDROXIDE SOLUTION

The kinetics of hydrogen evolution reaction on cobalt monosilicide CoSi in potassium hydroxide solution was studied using methods of polarization and impedance measurements. Electrochemical impedance of CoSi was studied in 1 M KOH at 21-22 °C in the range of potentials of hydrogen evolution. Solutions were prepared from high-purity reagents and de-ionized water (Milli-Q). The working solutions were de-aerated with hydrogen (purity 99.999 %). Cobalt silicide was prepared from silicon (99.99 % purity) and electrolytic cobalt (99.98 % purity) by Czochralski method (pulling from the melt at speed of 0.4 mm/min). Electrodes were cut using electric-spark method. The working electrode surface was 0.4 – 0.6 cm2. Before measurements, the working electrode surface was abraded with emery papers of 1000 and 2000, cleaned with ethanol and washed in the working solution. Electrochemical measurements were carried out in three-electrode electrochemical cell with cathodic and anodic compartments separated with a porous glass diaphragm. Potentials Е were changed from low to high cathodic polarisations and vice versa. Before recording an impedance spectrum at each potential value, the electrode was polarised under potentiostatic conditions until constant value of current was reached. The electrode potentials are given with respect to the SHE. Impedance measurements were carried out using FRA Solartron and potentiostat Solartron 1280 (Solartron Analytical) in the frequency range from 10 kHz to 0.01 Hz (10 points per decade). The alternating signal amplitude was 10 mV. The CorrWare2, ZPlot2 and ZView2 software (Scribner Associates, Inc.) was used for measuring and processing the impedance data. In 1 М KOH polarization curve for CoSi-electrode has Tafel plot with the slope bk = 0.113 V. Earlier it was established that b for Со2Ѕі and CoSi2 at these conditions were 0.123 and 0.105 V, respectively, while b for Co was equal to 0.144 V. Tafel slope for cobalt monosilicide is less than Co, i.e. the difference between the current densities on the silicide and cobalt increases with increasing in cathodic polarization. At a constant electrode potential E, the current density i for CoSi is higher than for Co (at E = -1.2 V the value of i for CoSi is equal to 1.58 mA/cm2, and for Co i = 0.32 mA/cm2). Nyquist diagrams consist of the combination of capacitive semicircle at high frequencies and an inductive arc at low frequencies. Impedance spectra of cobalt silicide can not be accurately described by a simple equivalent circuit consisting of parallel-connected charge transfer resistance and the double layer capacitance. In order to describe the behavior of CoSi - electrode in 1 M KOH solution in the range of investigated potentials the equivalent circuit was used which was obtained in several works as a model of two-stage process with the adsorption of intermediate substances, in particular for hydrogen evolution reaction. In order to analyze the impedance data we used the diagnostic criteria for hydrogen evolution reaction mechanisms, based on the dependence of equivalent circuit elements on the overvoltage and OH- ions concentration, which were previously proposed. Determination of the kinetic parameters (rate constants and transfer coefficients) of hydrogen evolution reaction steps on the basis of the impedance data has been considered. Hydrogen evolution reaction on CoSi electrode in alkaline solution is discussed using the proposed criteria. It has been shown that hydrogen evolution reaction on CoSi in potassium hydroxide solution proceeds through the Volmer-Heyrovsky route with Heyrovsky reaction as the rate-determining and with the Langmuir isotherm for hydrogen adsorption. Forcitation:Shamsutdinov A.Sh., Shein A.B. Cathodic hydrogen evolution on cobalt monosilicide in potassium hydroxide solution. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 9-15

Production of paper from pineapple leaves

Wood is used as the major raw material in paper production around the world and this has resulted in severe deforestations having direct negative impact on our environment. This has led to the need of finding alternative raw materials for paper production. Mauritius has around 300ha of land under pineapple cultivation resulting in agro-waste materials of the leaves. This paper aims at determining the feasibility of using pineapple leaf fibres for paper production. Samples of pineapple leaf fibre were mixed with cane-bagasse in different ratios namely, 20:80, 40:60, 60:40, 80:20,100:0. Pineapple leaf fibres were also mixed with wastepaper in the same ratios. Pulping of pineapple leaf was achieved through soda pulping at a concentration of 15%w/v for 90min at 90°C. The papers obtained were tested for their physical and mechanical properties. The average thickness of all the papers produced, ranged from 0.232mm to 0.304mm showing an increase in paper thickness with increasing grammage from 58.19g/m2 to 63.3g/m2. The most absorbent paper(1.19s) was found to be the 100% pineapple which also demonstrated the highest Tensile Index and Burst Index (6.5Nm/g and 0.84kPam2/g respectively). The bagasse and pineapple composite of ratio 40:60 was found to be the most abrasion resistant paper with 21 turns and a weight loss of 0.86% with the use of emery paper of grade zero as abradant and 200g load cells. The most crease resistant paper was the wastepaper and pineapple composite of ratio 80:20 with a crease recovery angle of 59.8°.