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Journal Details
Format
Journal
eISSN
2083-4799
ISSN
1730-2439
First Published
23 Sep 2008
Publication timeframe
4 times per year
Languages
English

Search

Volume 12 (2012): Issue 2 (June 2012)

Journal Details
Format
Journal
eISSN
2083-4799
ISSN
1730-2439
First Published
23 Sep 2008
Publication timeframe
4 times per year
Languages
English

Search

4 Articles
Open Access

Quantum chemical study of organic inhibitors of corrosion and hydrogen absorption An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel

Published Online: 22 Oct 2012
Page range: 5 - 18

Abstract

ABSTRACT

Results of quantum chemical calculations of the molecules of organic inhibitors (Oin) of corrosion and hydrogen absorption by metals (particularly, p-R-C6H4-SO2-NH2 where R= F, Cl, Br, CH3) both in free state and adsorbed on cluster modeling aluminium surface containing 20 atoms of Al are compared to experimental data on efficiencies of protective action (EPA) against corrosion by this metal. Energies of boundary orbitals (HOMO, LUMO) and dipole moments of isolated molecules of Oin as well as changes of atomic charges on Oin atoms when Oin molecule adsorbed have been computed using semi-empiric MNDO quantum chemistry method. It was found that correlation coefficients between EPA and changes of electric charge on N atom [ΔQ(N)] and O atom [ΔQ(O)] due to adsorption of Oin on the metal surface are the most significant. At adsorption and eventually the protection action of Oin, the specific role of polar groups (such as hydroxile) and specific role of heteroatoms (such as N, S etc) in the framework of the concepts of molecular orbitals and donor-acceptor interaction between adsorbent and adsorbate.

Keywords:

  • Quantum Chemistry
  • Corrosion Inhibitor
  • Protective Action
  • Boundary Orbitals
  • HOMO
  • LUMO,Mulliken Charges
  • MNDO
  • Heteroatom
  • Adsorption
  • Hydrogen Absorption
  • Pair Correlation
  • QuantumChemical Descriptors.
Open Access

An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel

Published Online: 22 Oct 2012
Page range: 19 - 30

Abstract

ABSTRACT

The paper presents an investigation of the mechanism of bainite transformation in 0.2C-1V-2Mn steel using high speed dilatometry and TEM backed by thermodynamic analysis. Obtained results confirm the incomplete reaction phenomenon with the cessation of the bainite transformation well before paraequilibrium is achieved. These experimental data indicate that bainitic ferrite forms by a displacive transformation mechanism, but soon afterwards, excess of carbon is partitioned into the residual austenite. The results are discussed in terms of the mechanism of bainite transformation.

Keywords:

  • mechanism of bainite transformation
  • lower
  • upper bainite
  • carbon partitioning
Open Access

Heat treatment enhancement of natural orange-red sapphires

Published Online: 22 Oct 2012
Page range: 31 - 44

Abstract

ABSTRACT

Certain variety of Madagascar color sapphires (fancy sapphires) has orange-red color, which shades don’t let to consider them as the rubies. Heat treatment experiments in reducing atmosphere were carried out on such sapphires for the purpose of improving their color characteristics. Chromium (III), iron (II and III), titanium (IV) chromophore impurities in natural corundum and chromophore centers with their participitation are considered. A special attention is paid to spectral characteristics of chromophore centers. Behavior of the chromophore centers under heat treatment and their influence on the color of fancy sapphires are studied. Color modification mechanism was proposed on the basis of microprobe and spectral analyses data. The proposed enhancement technique allows to improve color characteristics of fancy sapphires.

Keywords

  • corundum
  • fancy sapphires
  • enhancement
  • heat treatment
  • chromophore center
Open Access

The influence of biological environment on the appearance of silver-coated implants

Published Online: 22 Oct 2012
Page range: 45 - 50

Abstract

ABSTRACT

Despite antibiotics preventive treatment before and after implantation, risk of infection is real. The infections at the implant surface developein a few months after applying them into the body. To prevent the development of bacteria and to reduce the risk of infection, implants coated with silver layer come into use. The paper presents the research results in biological environment on vein and orthopaedicimplants covered with silver.

Keywords:

  • vein implants
  • orthopaedic implant
  • silver
  • biological environment
4 Articles
Open Access

Quantum chemical study of organic inhibitors of corrosion and hydrogen absorption An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel

Published Online: 22 Oct 2012
Page range: 5 - 18

Abstract

ABSTRACT

Results of quantum chemical calculations of the molecules of organic inhibitors (Oin) of corrosion and hydrogen absorption by metals (particularly, p-R-C6H4-SO2-NH2 where R= F, Cl, Br, CH3) both in free state and adsorbed on cluster modeling aluminium surface containing 20 atoms of Al are compared to experimental data on efficiencies of protective action (EPA) against corrosion by this metal. Energies of boundary orbitals (HOMO, LUMO) and dipole moments of isolated molecules of Oin as well as changes of atomic charges on Oin atoms when Oin molecule adsorbed have been computed using semi-empiric MNDO quantum chemistry method. It was found that correlation coefficients between EPA and changes of electric charge on N atom [ΔQ(N)] and O atom [ΔQ(O)] due to adsorption of Oin on the metal surface are the most significant. At adsorption and eventually the protection action of Oin, the specific role of polar groups (such as hydroxile) and specific role of heteroatoms (such as N, S etc) in the framework of the concepts of molecular orbitals and donor-acceptor interaction between adsorbent and adsorbate.

Keywords:

  • Quantum Chemistry
  • Corrosion Inhibitor
  • Protective Action
  • Boundary Orbitals
  • HOMO
  • LUMO,Mulliken Charges
  • MNDO
  • Heteroatom
  • Adsorption
  • Hydrogen Absorption
  • Pair Correlation
  • QuantumChemical Descriptors.
Open Access

An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel

Published Online: 22 Oct 2012
Page range: 19 - 30

Abstract

ABSTRACT

The paper presents an investigation of the mechanism of bainite transformation in 0.2C-1V-2Mn steel using high speed dilatometry and TEM backed by thermodynamic analysis. Obtained results confirm the incomplete reaction phenomenon with the cessation of the bainite transformation well before paraequilibrium is achieved. These experimental data indicate that bainitic ferrite forms by a displacive transformation mechanism, but soon afterwards, excess of carbon is partitioned into the residual austenite. The results are discussed in terms of the mechanism of bainite transformation.

Keywords:

  • mechanism of bainite transformation
  • lower
  • upper bainite
  • carbon partitioning
Open Access

Heat treatment enhancement of natural orange-red sapphires

Published Online: 22 Oct 2012
Page range: 31 - 44

Abstract

ABSTRACT

Certain variety of Madagascar color sapphires (fancy sapphires) has orange-red color, which shades don’t let to consider them as the rubies. Heat treatment experiments in reducing atmosphere were carried out on such sapphires for the purpose of improving their color characteristics. Chromium (III), iron (II and III), titanium (IV) chromophore impurities in natural corundum and chromophore centers with their participitation are considered. A special attention is paid to spectral characteristics of chromophore centers. Behavior of the chromophore centers under heat treatment and their influence on the color of fancy sapphires are studied. Color modification mechanism was proposed on the basis of microprobe and spectral analyses data. The proposed enhancement technique allows to improve color characteristics of fancy sapphires.

Keywords

  • corundum
  • fancy sapphires
  • enhancement
  • heat treatment
  • chromophore center
Open Access

The influence of biological environment on the appearance of silver-coated implants

Published Online: 22 Oct 2012
Page range: 45 - 50

Abstract

ABSTRACT

Despite antibiotics preventive treatment before and after implantation, risk of infection is real. The infections at the implant surface developein a few months after applying them into the body. To prevent the development of bacteria and to reduce the risk of infection, implants coated with silver layer come into use. The paper presents the research results in biological environment on vein and orthopaedicimplants covered with silver.

Keywords:

  • vein implants
  • orthopaedic implant
  • silver
  • biological environment

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