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Savko Malinov - One of the best experts on this subject based on the ideXlab platform.
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Surface gas nitriding: phase composition and microstructure
Titanium Alloys, 2009Co-Authors: Wei Sha, Savko MalinovAbstract:This chapter is about experimental research using differential scanning calorimeter while nitriding titanium alloys at various temperatures and for various periods. X-ray diffraction technique reveals the phase transformations that occur during gas nitriding. Because of the nitrogen interaction, a nitrided layer is formed that consists of titanium nitrides, followed by an Interstitial Solution of nitrogen in titanium. The microstructural changes in relation to the alloy composition and processing parameters are detailed. The microstructure of alloys nitrided at temperatures below their β-transus temperatures is uniform and homogeneous. With an increase of temperature above their β-transus temperatures, the microstructure changes to irregular.
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titanium alloys after surface gas nitriding
Surface & Coatings Technology, 2006Co-Authors: A. Zhecheva, Savko MalinovAbstract:Abstract Experimental studies using differential scanning calorimetry (DSC) for nitriding of four titanium-alloys near α Ti–8Al–1Mo–1V, near α Ti–6Al–2Sn–4Zr–2Mo, α + β Ti–6Al–4V and near β Ti–10V–2Fe–3Al at different temperatures and for different periods of time are presented. The X-ray diffraction (XRD) technique was used in order to study the phase transformations that occur during gas nitriding. As a result of the nitrogen interaction, a nitrided layer was formed that consists of titanium nitrides, followed by an Interstitial Solution of nitrogen in the hcp α titanium phase. The microstructural changes of these alloys in relation to the alloy composition and processing parameters were studied. It was found that the microstructure of alloys nitrided at temperatures below their β transus temperatures for various periods of time is uniform and homogeneous. With the increase of the temperature above their β transus temperatures the microstructure changes to irregular. Microindentation hardness testing using a Knoop indenter was conducted on the nitrided titanium alloys to analyse their hardness evolution in relation to the nitriding processing parameters and alloy composition. It was found that the microhardness increases with the increase of the temperature and time of nitriding. The surface morphology of the Ti–6Al–2Sn–4Zr–2Mo alloy in relation to the nitriding processing parameters was analysed.
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titanium alloys after surface gas nitriding
Surface & Coatings Technology, 2006Co-Authors: A. Zhecheva, Savko MalinovAbstract:Abstract Experimental studies using differential scanning calorimetry (DSC) for nitriding of four titanium-alloys near α Ti–8Al–1Mo–1V, near α Ti–6Al–2Sn–4Zr–2Mo, α + β Ti–6Al–4V and near β Ti–10V–2Fe–3Al at different temperatures and for different periods of time are presented. The X-ray diffraction (XRD) technique was used in order to study the phase transformations that occur during gas nitriding. As a result of the nitrogen interaction, a nitrided layer was formed that consists of titanium nitrides, followed by an Interstitial Solution of nitrogen in the hcp α titanium phase. The microstructural changes of these alloys in relation to the alloy composition and processing parameters were studied. It was found that the microstructure of alloys nitrided at temperatures below their β transus temperatures for various periods of time is uniform and homogeneous. With the increase of the temperature above their β transus temperatures the microstructure changes to irregular. Microindentation hardness testing using a Knoop indenter was conducted on the nitrided titanium alloys to analyse their hardness evolution in relation to the nitriding processing parameters and alloy composition. It was found that the microhardness increases with the increase of the temperature and time of nitriding. The surface morphology of the Ti–6Al–2Sn–4Zr–2Mo alloy in relation to the nitriding processing parameters was analysed.
A. Zhecheva - One of the best experts on this subject based on the ideXlab platform.
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titanium alloys after surface gas nitriding
Surface & Coatings Technology, 2006Co-Authors: A. Zhecheva, Savko MalinovAbstract:Abstract Experimental studies using differential scanning calorimetry (DSC) for nitriding of four titanium-alloys near α Ti–8Al–1Mo–1V, near α Ti–6Al–2Sn–4Zr–2Mo, α + β Ti–6Al–4V and near β Ti–10V–2Fe–3Al at different temperatures and for different periods of time are presented. The X-ray diffraction (XRD) technique was used in order to study the phase transformations that occur during gas nitriding. As a result of the nitrogen interaction, a nitrided layer was formed that consists of titanium nitrides, followed by an Interstitial Solution of nitrogen in the hcp α titanium phase. The microstructural changes of these alloys in relation to the alloy composition and processing parameters were studied. It was found that the microstructure of alloys nitrided at temperatures below their β transus temperatures for various periods of time is uniform and homogeneous. With the increase of the temperature above their β transus temperatures the microstructure changes to irregular. Microindentation hardness testing using a Knoop indenter was conducted on the nitrided titanium alloys to analyse their hardness evolution in relation to the nitriding processing parameters and alloy composition. It was found that the microhardness increases with the increase of the temperature and time of nitriding. The surface morphology of the Ti–6Al–2Sn–4Zr–2Mo alloy in relation to the nitriding processing parameters was analysed.
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titanium alloys after surface gas nitriding
Surface & Coatings Technology, 2006Co-Authors: A. Zhecheva, Savko MalinovAbstract:Abstract Experimental studies using differential scanning calorimetry (DSC) for nitriding of four titanium-alloys near α Ti–8Al–1Mo–1V, near α Ti–6Al–2Sn–4Zr–2Mo, α + β Ti–6Al–4V and near β Ti–10V–2Fe–3Al at different temperatures and for different periods of time are presented. The X-ray diffraction (XRD) technique was used in order to study the phase transformations that occur during gas nitriding. As a result of the nitrogen interaction, a nitrided layer was formed that consists of titanium nitrides, followed by an Interstitial Solution of nitrogen in the hcp α titanium phase. The microstructural changes of these alloys in relation to the alloy composition and processing parameters were studied. It was found that the microstructure of alloys nitrided at temperatures below their β transus temperatures for various periods of time is uniform and homogeneous. With the increase of the temperature above their β transus temperatures the microstructure changes to irregular. Microindentation hardness testing using a Knoop indenter was conducted on the nitrided titanium alloys to analyse their hardness evolution in relation to the nitriding processing parameters and alloy composition. It was found that the microhardness increases with the increase of the temperature and time of nitriding. The surface morphology of the Ti–6Al–2Sn–4Zr–2Mo alloy in relation to the nitriding processing parameters was analysed.
Vinod Raphael Palayoor - One of the best experts on this subject based on the ideXlab platform.
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Efficacies of sodium nitrite and sodium citrate–zinc acetate mixture to inhibit steel rebar corrosion in simulated concrete Interstitial Solution contaminated with NaCl
International Journal of Industrial Chemistry, 2018Co-Authors: Binsi Paulson Maliekkal, Joby Thomas Kakkassery, Vinod Raphael PalayoorAbstract:Investigations were carried out to compare the effectiveness of compounds such as sodium nitrite, trisodium citrate (TSC) and TSC–zinc acetate to inhibit the corrosion of steel rebar in simulated concrete Interstitial Solution contaminated with chloride and to explain the mechanism of corrosion inhibition on reinforcing steel by these systems. Inhibition efficiency of these systems was studied by electrochemical techniques such as potentiodynamic polarization and half cell potential measurements. Electronic spectral studies of simulated pore Solution and FT-IR spectral investigations of the film deposited on steel surface were carried out for understanding the mechanism of corrosion inhibition. Microscopic surface analysis was conducted to obtain the surface morphological behaviour of steel rebar. TSC alone was not exhibited good corrosion inhibition at very low and high concentrations according to electrochemical studies. However, in the presence of zinc acetate, corrosion protection efficiency of TSC increased appreciably. When comparing with sodium nitrite, TSC in the presence and absence of zinc acetate displayed good corrosion inhibition efficiency. Among a number of samples, TSC 100 ppm-zinc acetate 50 ppm combination showed maximum corrosion inhibition efficiency on steel rebar in simulated concrete Interstitial Solution.
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efficacies of sodium nitrite and sodium citrate zinc acetate mixture to inhibit steel rebar corrosion in simulated concrete Interstitial Solution contaminated with nacl
International Journal of Industrial Chemistry, 2018Co-Authors: Binsi Paulson Maliekkal, Joby Thomas Kakkassery, Vinod Raphael PalayoorAbstract:Investigations were carried out to compare the effectiveness of compounds such as sodium nitrite, trisodium citrate (TSC) and TSC–zinc acetate to inhibit the corrosion of steel rebar in simulated concrete Interstitial Solution contaminated with chloride and to explain the mechanism of corrosion inhibition on reinforcing steel by these systems. Inhibition efficiency of these systems was studied by electrochemical techniques such as potentiodynamic polarization and half cell potential measurements. Electronic spectral studies of simulated pore Solution and FT-IR spectral investigations of the film deposited on steel surface were carried out for understanding the mechanism of corrosion inhibition. Microscopic surface analysis was conducted to obtain the surface morphological behaviour of steel rebar. TSC alone was not exhibited good corrosion inhibition at very low and high concentrations according to electrochemical studies. However, in the presence of zinc acetate, corrosion protection efficiency of TSC increased appreciably. When comparing with sodium nitrite, TSC in the presence and absence of zinc acetate displayed good corrosion inhibition efficiency. Among a number of samples, TSC 100 ppm-zinc acetate 50 ppm combination showed maximum corrosion inhibition efficiency on steel rebar in simulated concrete Interstitial Solution.
K. H. J. Buschow - One of the best experts on this subject based on the ideXlab platform.
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R2Fe17Cx and R2Fe17Nx compounds studied by means of 57Fe,166Er and 169Tm Mössbauer spectroscopy
Journal of Magnetism and Magnetic Materials, 1992Co-Authors: P.c.m. Gubbens, T. H. Jacobs, A.a. Moolenaar, K. H. J. BuschowAbstract:Abstract The temperature dependence of the 57Fe Mossbauer spectra of R2Fe17Cx and R2Fe17N2.7 with R = Er and Tm shows a hyperfine field anomaly around the spin reorientation temperature. From the quadrupolar splitting of the 166Er and 169Tm Mossbauer spectra of R2Fe17Cx and R2Fe17N2.7 it was derived that Interstitial Solution of C or N atoms strongly increases the second order crystal field constant A02 with the exception of Tm2Fe17N2.7.
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Change of magnetic properties of Th2Fe17 due to Interstitial Solution of C and N
Journal of Applied Physics, 1991Co-Authors: T. H. Jacobs, Gary J. Long, O. Allan Pringle, F. Grandjean, K. H. J. BuschowAbstract:The changes in magnetic and crystallographic properties in the series Th2Fe17Cx and Th2Fe17Nx have been studied. The changes in the latter series were also studied by 57Fe Mossbauer spectroscopy. The ultimate enhancements of the saturation moments in these series are 13% and 24%, respectively. This is much larger than observed previously in the corresponding rare‐earth compounds, although the Curie temperature enhancements are of comparable magnitude. In the Th–Fe–C system a novel compound of the BaCd11 type was found, having a Curie temperature around 370 K.
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Nuclear magnetic resonance study and Curie temperature of Y2Co17Cx
Journal of the Less Common Metals, 1991Co-Authors: Cz. Kapusta, M. Rosenberg, K. V. Rao, Zheng-he Han, T. H. Jacobs, K. H. J. BuschowAbstract:Abstract The system Y2Co17Cx was investigated by nuclear magnetic resonance zero field spin echo spectroscopy of 89Y. From the satellite line intensity it was deduced that the limiting concentration of the Interstitial Solution of carbon is very low and corresponds to x = 0.07. The relative insensitivity of the Curie temperature to carbon concentration in this system is in agreement with this behaviour.
Jeanpaul Balayssac - One of the best experts on this subject based on the ideXlab platform.
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combination of the wenner resistivimeter and torrent permeameter methods for assessing carbonation depth and saturation level of concrete
Construction and Building Materials, 2018Co-Authors: Stephanie Bonnet, Jeanpaul BalayssacAbstract:Abstract Assessing carbonation depth is of great interest for the diagnosis of reinforced concrete structures because carbonation is one of the origins of steel corrosion. The assessment of carbonation depth is usually performed by a simple and reliable semi-destructive test consisting in spraying a colored indicator on a sample extracted from the structure. When the structure is large, this test must be reproduced many times if an assessment of the variability of carbonation depth is required. In this case, the extraction of multiple samples can be prohibitive from the technical and economic points of view. So, in this case, a non-destructive testing (NDT) method could be relevant. However, even when NDT methods can be used, there is a need to improve the interpretation of their results. In this study, the use of two usual NDT methods is proposed: resistivity measurement by a Wenner probe and surface permeability assessment by a Torrent permeameter. Both techniques are implemented on carbonated slabs having different carbonated depths and at different saturation degrees. The results show that the two techniques are sensitive to moisture and carbonation. For a given saturation level, resistivity increases when the carbonated depth increases and resistivity decreases when the saturation level increases. Torrent permeability decreases when the saturation degree and carbonated depth increase. Good repeatability is observed for resistivity measurements while a larger scatter is obtained for Torrent permeability. Empirical laws are built for the relationships between resistivity or permeability and saturation degree and carbonated depth. For resistivity, either a linear model between resistivity and saturation degree is used or Archie’s law is adapted to take the effect of carbonation into account. Following the same idea, a linear law between Torrent permeability and saturation degree is adapted to the effect of carbonation. Because resistivity can be measured only if the saturation degree is rather high, i.e. if there is a continuity of the Interstitial Solution, and because permeability assessment is impossible if the concrete is fully saturated, these laws are limited to saturation degrees in the 40–83% range. Then, these laws are used to predict carbonation depth and saturation degree on a wall designed with the same concrete but stored in different conditions. The results show that resistivity and Torrent permeability can be used for the combined assessment of carbonation depth and saturation degree in laboratory conditions.
