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1
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Corrosion Properties of AISI 4140 Industrial Steels Coated with Aniline in Different Storage Conditions

100%
Karahan İ.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 1
286-288
EN
Polyaniline (PANI) was successfully deposited by means of cyclic voltammetry technique from 0.10 M aniline containing 0.30 M oxalic acid and 1 g/l H₃BO₃ solution on AISI 4140 steel electrode. In this investigation nominate scan rates 25, 50, 75, and 100 mV/s have been examined. PANI film was characterized using optical microscope; it was covered with a dark green-yellow homopolymer film of strongly adherent homogeneous characteristic. The corrosion behaviour of the steel electrodes with and without PANI film in 3.5% NaCl solution was investigated through anodic polarization curves. The results indicated that PANI coating led to decrease of the permeability of metallic plating. The PANI homopolymer film provided an effective barrier property and a remarkable anodic protection to substrate.
2
Content available remote

Effects of Blanking Speed on the Shear Surface of Mild Steel (St37)

80%
Kanca E., Eyercıoğlu O., Karahan I., Günen A., Göv K.
Acta Physica Polonica A
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2016
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vol. 130
|
issue 1
370-374
EN
Blanking operation is widely used to cut sheet or plates by a shearing process between punch and die. The process of shearing and the conditions of the sheared surface are influenced by the punch, the die, the speed of punching, the clearance between the punch and the die. In this study, effects of high speed blanking on surface quality and corrosion properties of mild steel St37 shear surface have been investigated. The work presented in this paper aims at evaluating the shear surface quality improvements of the St37 resulting from the use of high energy rate forging machine. The appraisal is based on criteria related to surface accuracy and corrosion resistance characterization. For this purpose, St37 mild steels were cut using three different punch speeds hydraulic presses at nearly quasistatic, conventional mechanical presses at low punch velocity (0.2 m/s) and high energy rate forging machine at high punch velocity (10 m/s), for different die clearances (4.5%-6% of sheet thickness). After accelerated corrosion tests, blanks were performed in conjunction with scanning electron microscopy technique to study the cutting process of the blanks at room temperature. In fact, by using high energy rate forging machine, a reduction of more than 25% of the surface roughness (R_{a}) was realized and better resistance to stress corrosion cracking and pitting corrosion was noticed. It was observed that the corrosion resistance of the high energy rate forging-cut specimen was better than that of the hydraulic-cut and mechanical-cut specimens.
3
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Synthesis and Characterization of Phenol/Urea/Formaldehyde and Clay Composites

80%
Doğar Ç., Gürses A., Köktepe S., Mindivan F., Güneş K., Aktürk S.
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vol. 125
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issue 2
374-378
EN
Recently, so-called "phenol-formaldehyde-urea resins", which are generally made only by mechanical blending of UF resin and alkaline type PF resins, have been used as adhesives for the manufacturing of wood products. Faster curing PF resins can be also prepared by the addition of urea during or after the resin synthesis to yield co-condensed phenol-urea-formaldehyde (PUF) resins. In this study, resin/clay composites were prepared by in situ polymerization of phenol(18.2%)-urea(36.3%)-formaldehyde(45.5%) (PUF) with the various ratios of organoclay (7.69-45.45%) and colored organoclay (3.22-20.0%). The objective of our work is the investigation of the effect of addition of both organoclay and colored organoclay at different ratios on the textural characteristics. The composites are characterized by X-ray diffraction, Fourier transform infrared spectroscopy techniques and using high resolution transmission electron microscopy images of the samples. It was found that clay layers exfoliated in the resin matrix.
4
Content available remote

Electrodeposition and Corrosive Properties of Environmental ZnFe/Polyaniline on Low Carbon Steel

80%
Karahan İ., Tiltil F.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 1
282-285
EN
Zinc-iron alloy plating (ZnFe) was successfully deposited on AISI 4140 steel applying cyclic voltammetry technique. Polyaniline (PANI) film was synthesized with cyclic voltammetry technique from 0.10 M aniline containing 0.30 M oxalic acid solution on zinc-iron plated carbon steel (AISI4140/ZnFe) electrode. ZnFe film was characterized by scanning electron microscopy and X-ray diffraction technique. The corrosion behaviour of zinc-iron deposited carbon steel electrodes with and without PANI film in 3.5% NaCl solution was investigated with polarization curves. Effect of pH and current density on the synthesis of the aniline was also examined. The results showed that PANI coating led to decrease of the permeability of metallic plating. The PANI homopolymer film provided an effective barrier property on zinc-iron coating and a remarkable anodic protection to substrate. ZnFe particles had more homogeneous, smooth prismatic structure. It is suggested that ZnFe/PANI deposits produced in the bath applying 0.1 mA/cm² current density probably offer bigger protection to the steel substrate.
5
Content available remote

Silicon Etching in XeF_2 Environment

80%
Knizikevičius R.
Acta Physica Polonica A
|
2013
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vol. 124
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issue 1
137-140
EN
Enhancement of silicon etching rate in XeF_2 environment is considered by a proposed model, which includes processes of adsorption, activation, chemical reactions, relaxation, desorption, and sputtering. The enhancement of silicon etching rate is explained by considering hydrocarbon molecules from background gas contamination in the vacuum chamber, and assuming that hydrocarbon radicals enhance the etching rate. The composition of the adsorbed layer during silicon etching in XeF_2 environment is calculated. It is found that hydrocarbon radicals intensify reaction of XeF_2 molecules with Si atoms on the surface and that this changes the kinetics of the etching rate. Using the obtained theoretical results the difference in kinetics of the etching rates of first and subsequent run is explained.
6
Content available remote

Micro-Abrasion Wear Behavior of Thermal-Spray-Coated Steel Tooth Drill Bits

80%
Günen A.
Acta Physica Polonica A
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2016
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vol. 130
|
issue 1
217-222
EN
Wear behavior of four kinds of thermally sprayed coatings on steel tooth drill bits have been investigated by micro-abrasion wear test. The fixed ball micro abrasion wear test was applied for bare substrate and for thermal sprayed substrate of each sample. SiC and Al₂O₃ abrasive powders with grain size of 5 μm were used in the abrasion experiments. Ball rotational speed values of 140 rpm and applied loads of 1, 2 and 3 N were used. Experimental results show that the wear mechanisms of the coatings are micro-grooving and micro-rolling. Application of the coatings was found to have an influence on the wear mechanism of the samples. The results also indicate that wear resistance of thermally sprayed coatings can be correlated to porosity, hardness, plasticity, toughness, and cohesion properties of the coatings. In addition, wear resistance of the coated samples had increased in accordance with the increasing coating thickness.
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