ABSTRACT In this study, a plasma electrolytic oxidation (PEO) process was used to produce oxide coatings on commercially pure aluminium (1100 alloy) at a pulsed dc power mode. The effects of process parameters (i.e. current density and... more
ABSTRACT In this study, a plasma electrolytic oxidation (PEO) process was used to produce oxide coatings on commercially pure aluminium (1100 alloy) at a pulsed dc power mode. The effects of process parameters (i.e. current density and treatment time) on the plasma discharge behaviour during the PEO treatment were investigated using optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285–800 nm). The elements present in the plasma were identified. Stark shifts of spectral lines and line intensity ratios were utilized to determine the plasma electron concentrations and temperatures, respectively. The plasma electron temperature profile, coating surface morphology and coating composition were used to interpret the plasma discharging behaviour. The different coating morphologies and compositions at different coating surface regions are explained in terms of three types of discharge, which originate either at the substrate/coating interface, within the upper layer, or at the coating top layer. The high spike peaks on the plasma intensity and temperature profiles corresponded to discharges originated from the substrate/coating interface, while the base line and small fluctuations were due to discharges at the coating/electrolyte interface.
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... Phys., 45 (1974) 2313. 29 GC Vayenas and JN Michaels, Surf. Sei., 120 (1982) L405. 30 WE Bell and M. Tagami, J. Phys. Chem., 67 (1963) 2432. 31 M. Hecq and A. Hecq, J. Less-Common Met., 56 (1977) 133. 32 M. Hecq, A. Hecq and T.... more
... Phys., 45 (1974) 2313. 29 GC Vayenas and JN Michaels, Surf. Sei., 120 (1982) L405. 30 WE Bell and M. Tagami, J. Phys. Chem., 67 (1963) 2432. 31 M. Hecq and A. Hecq, J. Less-Common Met., 56 (1977) 133. 32 M. Hecq, A. Hecq and T. Robert, J. Vac. Sei. ...
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Ag and Pt nanoparticles have successfully been synthesized by hydrolysis of eitherAg2Naor PtNa at room temperature. The oxidation of sodium in the Pt-Na pellets was much faster than that in the Ag-Na pellets since Pt is a catalyst... more
Ag and Pt nanoparticles have successfully been synthesized by hydrolysis of eitherAg2Naor PtNa at room temperature. The oxidation of sodium in the Pt-Na pellets was much faster than that in the Ag-Na pellets since Pt is a catalyst forH2Oformation reaction from hydrogen and oxygen at room temperature. The hydrolysis byproduct, NaOH, has a high solubility and easily is removed. This method offers a simple method of preparing transition metal nanoparticles. The Ag and Pt nanoparticles prepared by this method were crystalline in nature, and spherical in shape with a mean size of around 10 nm.
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The influence of various alloying elements on the thermoelectric power (TEP) of zirconium is determined. The data indicate that the thermoelectric power is very sensitive to both the type of alloying element and its solubility in the... more
The influence of various alloying elements on the thermoelectric power (TEP) of zirconium is determined. The data indicate that the thermoelectric power is very sensitive to both the type of alloying element and its solubility in the α-phase of zirconium. For example, where tin strongly reduces the thermoelectric power of zirconium, the magnitude of the reduction increasing as the amount of tin in solution in α-Zr increases, the effect of niobium is much less pronounced and variable with first a decrease and then an increase in TEP with increasing niobium.
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MgNi2 has been shown to exhibit a hydrolysis behavior similar to that previously found for Mg2Ni. The Ni nanoparticles prepared by hydrolysis of MgNi2 were spherical in shape with a mean diameter of about 16 nm. Utilizing the hydrolysis... more
MgNi2 has been shown to exhibit a hydrolysis behavior similar to that previously found for Mg2Ni. The Ni nanoparticles prepared by hydrolysis of MgNi2 were spherical in shape with a mean diameter of about 16 nm. Utilizing the hydrolysis behavior of MgNi2 to produce Ni nanoparticles offers a higher efficiency than by using Mg2Ni, saves raw material and reduces any pollution resulting from the dissolution of the hydrolysis byproduct (Mg(OH)2) by using an acid.
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Traditional ‘indirect’ methods for studying microstructural changes include electrical resistivity, dilatometry and microhardness. These methods are ‘indirect’ in that they measure the variation of a property that is itself influenced by... more
Traditional ‘indirect’ methods for studying microstructural changes include electrical resistivity, dilatometry and microhardness. These methods are ‘indirect’ in that they measure the variation of a property that is itself influenced by changes in microstructure. A relatively new technique for this ‘indirect’ measurement of the microstructural changes is thermoelectric power (TEP) measurement. Such a technique has the advantages that it is
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... la. Page 488. MENG AND NORTHWOOD ON INTERMETALLIC PRECIPITATES 483 FIG. ... This is what was experimentally observed with there being not only less iron-containing intermetallic Page 489. 484 ZIRCONIUM IN THE NUCLEAR INDUSTRY «» SEC... more
... la. Page 488. MENG AND NORTHWOOD ON INTERMETALLIC PRECIPITATES 483 FIG. ... This is what was experimentally observed with there being not only less iron-containing intermetallic Page 489. 484 ZIRCONIUM IN THE NUCLEAR INDUSTRY «» SEC HI-HEW M FIG. ...
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The effects of temperature on the tensile properties and deformation behaviour of Ni/Ni3Al multilayer composites have been systematically investigated. With increasing tensile test temperature from room temperature to 600°C, the ultimate... more
The effects of temperature on the tensile properties and deformation behaviour of Ni/Ni3Al multilayer composites have been systematically investigated. With increasing tensile test temperature from room temperature to 600°C, the ultimate tensile strength decreased. The ‘abnormal’ strengthening of Ni3Al gave rise to a reduction in the capability for cooperative deformation between the Ni and the Ni3Al layers at elevated temperatures.
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Nitrocarburizing is an economical surface hardening process and is proposed as an alternative heat treatment method to carbonitriding. The focus of this study is to compare the size and shape distortion and residual stresses resulting... more
Nitrocarburizing is an economical surface hardening process and is proposed as an alternative heat treatment method to carbonitriding. The focus of this study is to compare the size and shape distortion and residual stresses resulting from the ferritic nitrocarburizing and gas ...