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Volume 22 (2022): Issue 2 (June 2022)

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Volume 21 (2021): Issue 2 (June 2021)

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Volume 15 (2015): Issue 4 (December 2015)

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Volume 12 (2012): Issue 4 (December 2012)

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Journal Details
Format
Journal
eISSN
2083-4799
First Published
23 Sep 2008
Publication timeframe
4 times per year
Languages
English

Search

Volume 22 (2022): Issue 2 (June 2022)

Journal Details
Format
Journal
eISSN
2083-4799
First Published
23 Sep 2008
Publication timeframe
4 times per year
Languages
English

Search

5 Articles
access type Open Access

Effects of B Addition on the Microstructure and Microhardness of Melt-Spun Al-7075 Alloy

Published Online: 12 Jul 2022
Page range: 5 - 18

Abstract

Abstract

Main aim of this study is to examine change of microstructural and the mechanical properties of Al-7075 alloy depending on B content added with different proportions. Rapid solidification process used to produce the alloys was carried out with a single roll melt spinner via a wheel with a rotational speed of 25 m/s. For the microstructural characterization of the alloys, a scanning electron microscope and X-ray diffraction analyzes were used. According to obtained results, it can be said that B addition led to modification of dimensions and shapes of both α−Al and intermetallic phases occurred, it reduced average grain size from 0.45 μm to 0.34 μm in the microstructure. The B addition also led to dramatically increase in microhardness of the Al-7075 alloy. The microhardness of the alloy with 0.4 wt. % B is 0.19 GPa, this is clearly one times higher than that of the alloy without B addition. The microhardness of the alloy with 1 wt. % B is 0.21 GPa, this is also slightly higher than that of the alloy with 0.4 wt. % B.

Keywords

  • Al-7075
  • B addition
  • microhardness
  • microstructure
  • rapid solidification
access type Open Access

Corrosion of Transparent Electrodes Study

Published Online: 12 Jul 2022
Page range: 19 - 27

Abstract

Abstract

This work reports a study of corrosion lifetime of transparent electrodes deposited on the microscopic glass substrate. A procedure was developed for obtaining the transparent electrode by spray method. The corrosion lifetime variation in the presence of 1.5 M NaOH medium chemically degraded at room temperature before and after gamma irradiation was determined by measuring the evolution of the structure, electrical and optical characteristics. The mean values of transmittance up to 25 month before and after irradiation were calculated 91% ±6% and 96±7%, respectively. The average value of resistivity after corrosion and age time after γ-irradiation was 0.016±9% Ω.cm and 0.017± 4% at 1.0 kHz. No significant changes observed for 27 hr corrosion and 25 month age time of the transparent electrodes in NaOH solution.

Keywords

  • electrodes
  • corrosion
  • γ-irradiation
access type Open Access

Enhancement Photocatalytic Activity of Mn Doped Cds/Zno Nanocomposites for the Degradation of Methylene Blue Under Solar Light Irradiation

Published Online: 12 Jul 2022
Page range: 28 - 48

Abstract

Abstract

In this study, Mn doped CdS/ZnO nanocomposites synthesized by co-precipitation method and its photocatalytic activity was tested using methylene blue under solar light irradiation. The prepared hybrid nanocomposites are characterized by using different physicochemical techniques including XRD, FESEM, EDX, TEM, UV-vis DRS and PL analysis. From the XRD analysis, Mn doped ZnO/CdS nanocomposite diffraction peaks only reflect the binary crystalline structures of ZnO and CdS. However, there is no characteristic peak of Mn is found that may be because of low content of Mn doped on ZnO/CdS. But Mn (2.9 wt%) was detected in the Mn doped ZnO/CdS nanocomposite, which was measured by EDX analysis. The FESEM and TEM results exhibit the surface particle of Mn doped ZnO/CdS nanocomposite which have spherical nature and confirmed the formation of Mn doped ZnO/CdS nanocomposites. The photocatalytic degradation results have revealed that the Mn doped CdS/ZnO nanocomposites exhibit admirable activity toward the photocatalytic degradation of the MB. The reason for excellent photocatalytic activity of Mn doped CdS/ZnO nanocomposites indicates the absorbance band shifted to red region and reduction of recombination of photogenerated electron-hole, which is in good agreement with UV-visible DRS analysis and PL study results. The fitted kinetic plots showed a pseudo-first-order reaction model and the appropriate rate constants were found to be 0.0068 min−1, 0.00846 min−1, and 0.0188 min−1, for ZnO, 25 % CdS/ZnO, and 0.8 mol% Mn doped CdS/ZnO nanocomposites, respectively. The maximum photocatalytic activity was achieved by 0.8 mol% Mn doped CdS/ZnO nanocomposites with a 95% degradation efficiency of MB. Hydroxyl and superoxide radicals, having a vital role in the degradation of MB, confirmed scavenging experiments. In addition, the recycling tests displays that the Mn doped CdS/ZnO nanocomposites have shown good stability and long durability. The enhanced photodegradation activity of Mn doped CdS/ZnO nanocomposites indicates the potential of the nanocomposite for the treatment of organic pollutants from the textile wastewater.

Keywords

  • Mn doped CdS/ZnO nanocomposites
  • methylene blue dye
  • solar light
  • dye degradation
  • TEM analysis
access type Open Access

Effect of Shop-Primer Coating on S235JR Steel on MAG Weldability

Published Online: 12 Jul 2022
Page range: 49 - 63

Abstract

Abstract

In this study, S235JR structural steel samples in uncoated condition and coated (shop-primer) in different thicknesses were welded by MAG (Metal Active Gas) welding method, and the effects of these applications on the mechanical and microstructure properties of the material were investigated. In the experimental studies, the first specimen group were used without any sandblasting and coating application, the second group specimens were sandblasted at Sa 2 ½ degree, and 25 µm, 50 µm, and 75 µm coatings were applied to the specimens in the other group. Surface conditions and coating thicknesses were selected as the variable parameters. With the examination of the radiography films, it was observed that the surface conditions affected the welded joint. As a result of the study, it was observed that altered coating thicknesses caused defects in the welding zone. It was determined that the coating thickness partially affected the mechanical properties, and the highest hardness values occurred in the weld zone in all samples. Relatively low values were obtained in tensile, bending and Charpy impact tests performed on sample groups with 75 µm coating thickness. The results were verified by the surface fracture, SEM, and EDS studies.

Keywords

  • Sandblasting, surface coating
  • shop-primer
  • MAG welding
  • microstructure
access type Open Access

Electrical Characteristics of Dry Cement – Based Composites Modified with Coconut Husk Ash Nanomaterial

Published Online: 12 Jul 2022
Page range: 64 - 77

Abstract

Abstract

Coconut husk is generated yearly as waste in large quantities but majorly under-utilized. Also, as a result of high embodied carbon, cement production is one of the largest contributors to construction sector carbon footprint. Since accumulation of unmanaged agro-waste like coconut husk has an increased environmental concern due to its pollution effect, recycling it into sustainable construction materials is a viable solution for future generation. In this study, experiments were performed to investigate the influence of coconut husk ash nanomaterial (CHAN) inclusion on electrical characteristics of plain cement paste (BCP) and mortar (CSM) samples at curing ages of 7 and 28 days. The results showed increase in electrical resistivity, thermal constant, and activation energy with curing duration for heating and cooling cycles of BCP and CSM. With inclusion of CHAN, the developed cement paste (CAP) and mortar (CASM) possessed lower values in all cases compared to their counterparts. Also, during heating at 28 days, both the CAP and CASM exhibited decrease in thermal constant. Though electrical resistance of all the samples varied inversely with temperature, CAP and CASM were found to possess greater potentials to make building structures intrinsically smart. Hence, in addition to solving disposal problems, utilization of coconut husks as described herein could enhance development of safe, inexpensive, and sustainable buildings that have large temperature sensing volume.

Keywords

  • Activation energy
  • building
  • electrical resistivity
  • temperature sensing
  • thermal constant
5 Articles
access type Open Access

Effects of B Addition on the Microstructure and Microhardness of Melt-Spun Al-7075 Alloy

Published Online: 12 Jul 2022
Page range: 5 - 18

Abstract

Abstract

Main aim of this study is to examine change of microstructural and the mechanical properties of Al-7075 alloy depending on B content added with different proportions. Rapid solidification process used to produce the alloys was carried out with a single roll melt spinner via a wheel with a rotational speed of 25 m/s. For the microstructural characterization of the alloys, a scanning electron microscope and X-ray diffraction analyzes were used. According to obtained results, it can be said that B addition led to modification of dimensions and shapes of both α−Al and intermetallic phases occurred, it reduced average grain size from 0.45 μm to 0.34 μm in the microstructure. The B addition also led to dramatically increase in microhardness of the Al-7075 alloy. The microhardness of the alloy with 0.4 wt. % B is 0.19 GPa, this is clearly one times higher than that of the alloy without B addition. The microhardness of the alloy with 1 wt. % B is 0.21 GPa, this is also slightly higher than that of the alloy with 0.4 wt. % B.

Keywords

  • Al-7075
  • B addition
  • microhardness
  • microstructure
  • rapid solidification
access type Open Access

Corrosion of Transparent Electrodes Study

Published Online: 12 Jul 2022
Page range: 19 - 27

Abstract

Abstract

This work reports a study of corrosion lifetime of transparent electrodes deposited on the microscopic glass substrate. A procedure was developed for obtaining the transparent electrode by spray method. The corrosion lifetime variation in the presence of 1.5 M NaOH medium chemically degraded at room temperature before and after gamma irradiation was determined by measuring the evolution of the structure, electrical and optical characteristics. The mean values of transmittance up to 25 month before and after irradiation were calculated 91% ±6% and 96±7%, respectively. The average value of resistivity after corrosion and age time after γ-irradiation was 0.016±9% Ω.cm and 0.017± 4% at 1.0 kHz. No significant changes observed for 27 hr corrosion and 25 month age time of the transparent electrodes in NaOH solution.

Keywords

  • electrodes
  • corrosion
  • γ-irradiation
access type Open Access

Enhancement Photocatalytic Activity of Mn Doped Cds/Zno Nanocomposites for the Degradation of Methylene Blue Under Solar Light Irradiation

Published Online: 12 Jul 2022
Page range: 28 - 48

Abstract

Abstract

In this study, Mn doped CdS/ZnO nanocomposites synthesized by co-precipitation method and its photocatalytic activity was tested using methylene blue under solar light irradiation. The prepared hybrid nanocomposites are characterized by using different physicochemical techniques including XRD, FESEM, EDX, TEM, UV-vis DRS and PL analysis. From the XRD analysis, Mn doped ZnO/CdS nanocomposite diffraction peaks only reflect the binary crystalline structures of ZnO and CdS. However, there is no characteristic peak of Mn is found that may be because of low content of Mn doped on ZnO/CdS. But Mn (2.9 wt%) was detected in the Mn doped ZnO/CdS nanocomposite, which was measured by EDX analysis. The FESEM and TEM results exhibit the surface particle of Mn doped ZnO/CdS nanocomposite which have spherical nature and confirmed the formation of Mn doped ZnO/CdS nanocomposites. The photocatalytic degradation results have revealed that the Mn doped CdS/ZnO nanocomposites exhibit admirable activity toward the photocatalytic degradation of the MB. The reason for excellent photocatalytic activity of Mn doped CdS/ZnO nanocomposites indicates the absorbance band shifted to red region and reduction of recombination of photogenerated electron-hole, which is in good agreement with UV-visible DRS analysis and PL study results. The fitted kinetic plots showed a pseudo-first-order reaction model and the appropriate rate constants were found to be 0.0068 min−1, 0.00846 min−1, and 0.0188 min−1, for ZnO, 25 % CdS/ZnO, and 0.8 mol% Mn doped CdS/ZnO nanocomposites, respectively. The maximum photocatalytic activity was achieved by 0.8 mol% Mn doped CdS/ZnO nanocomposites with a 95% degradation efficiency of MB. Hydroxyl and superoxide radicals, having a vital role in the degradation of MB, confirmed scavenging experiments. In addition, the recycling tests displays that the Mn doped CdS/ZnO nanocomposites have shown good stability and long durability. The enhanced photodegradation activity of Mn doped CdS/ZnO nanocomposites indicates the potential of the nanocomposite for the treatment of organic pollutants from the textile wastewater.

Keywords

  • Mn doped CdS/ZnO nanocomposites
  • methylene blue dye
  • solar light
  • dye degradation
  • TEM analysis
access type Open Access

Effect of Shop-Primer Coating on S235JR Steel on MAG Weldability

Published Online: 12 Jul 2022
Page range: 49 - 63

Abstract

Abstract

In this study, S235JR structural steel samples in uncoated condition and coated (shop-primer) in different thicknesses were welded by MAG (Metal Active Gas) welding method, and the effects of these applications on the mechanical and microstructure properties of the material were investigated. In the experimental studies, the first specimen group were used without any sandblasting and coating application, the second group specimens were sandblasted at Sa 2 ½ degree, and 25 µm, 50 µm, and 75 µm coatings were applied to the specimens in the other group. Surface conditions and coating thicknesses were selected as the variable parameters. With the examination of the radiography films, it was observed that the surface conditions affected the welded joint. As a result of the study, it was observed that altered coating thicknesses caused defects in the welding zone. It was determined that the coating thickness partially affected the mechanical properties, and the highest hardness values occurred in the weld zone in all samples. Relatively low values were obtained in tensile, bending and Charpy impact tests performed on sample groups with 75 µm coating thickness. The results were verified by the surface fracture, SEM, and EDS studies.

Keywords

  • Sandblasting, surface coating
  • shop-primer
  • MAG welding
  • microstructure
access type Open Access

Electrical Characteristics of Dry Cement – Based Composites Modified with Coconut Husk Ash Nanomaterial

Published Online: 12 Jul 2022
Page range: 64 - 77

Abstract

Abstract

Coconut husk is generated yearly as waste in large quantities but majorly under-utilized. Also, as a result of high embodied carbon, cement production is one of the largest contributors to construction sector carbon footprint. Since accumulation of unmanaged agro-waste like coconut husk has an increased environmental concern due to its pollution effect, recycling it into sustainable construction materials is a viable solution for future generation. In this study, experiments were performed to investigate the influence of coconut husk ash nanomaterial (CHAN) inclusion on electrical characteristics of plain cement paste (BCP) and mortar (CSM) samples at curing ages of 7 and 28 days. The results showed increase in electrical resistivity, thermal constant, and activation energy with curing duration for heating and cooling cycles of BCP and CSM. With inclusion of CHAN, the developed cement paste (CAP) and mortar (CASM) possessed lower values in all cases compared to their counterparts. Also, during heating at 28 days, both the CAP and CASM exhibited decrease in thermal constant. Though electrical resistance of all the samples varied inversely with temperature, CAP and CASM were found to possess greater potentials to make building structures intrinsically smart. Hence, in addition to solving disposal problems, utilization of coconut husks as described herein could enhance development of safe, inexpensive, and sustainable buildings that have large temperature sensing volume.

Keywords

  • Activation energy
  • building
  • electrical resistivity
  • temperature sensing
  • thermal constant

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