Journal of Metallurgical Engineering
[2 followers] Follow
Open Access journal
ISSN (Print) 2168-555X - ISSN (Online) 2168-5568
Published by Science and Eng Pub Co. [49 journals]
- Studies of Corrosion and Electrochemical Behavior of Cu-Zn Alloys in H2SO4
and HNO3 Acid Solutions
Abstract: Studies of Corrosion and Electrochemical Behavior of Cu-Zn Alloys in H2SO4 and HNO3 Acid Solutions
Author Walaa A. HusseinAmal S. I. AhmedWafaa A. GhanemGhalia A. Gabe
The electrochemical corrosion behavior of Cu-Zn alloys in different concentrations of H2SO4 and HNO3 acid solutions was studied using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Open-circuit measurements showed that both immersion potential (Eim.) and steady state potential (Es.s.) for the Cu-Zn alloys decreased and shifted to more negative values as the concentration of H2SO4 and HNO3 increased. The increase in acid concentration accompanied with increase in the corrosion current density, Icorr, corrosion rate, C.R. Also, it is observed that the anodic Tafel slope values are almost increased as the concentration of acid increased. The impedance response consisted of characteristic depressed semicircles which clarifying that the corrosion process occurs under charge transfer control. The presence of 2.43 % aluminum in the Alloy II improves the corrosion resistance in H2SO4 and HNO3 media as compared to Alloy I. The charge transfer resistance values, Rct, for the Cu-Zn alloys (I and II) in H2SO4 and HNO3 acid solutions follow the order: Alloy II > Alloy I. The results obtained from both methods were in good agreement. These results have also been confirmed through the SEM and EDX.
- Performance Evaluation of Conventional Tools and Hardfaced Chromium
Carbide Tools for Friction Stir Welded Copper Alloys Joints
Abstract: Performance Evaluation of Conventional Tools and Hardfaced Chromium Carbide Tools for Friction Stir Welded Copper Alloys Joints
Author Adimoolam BaskaranK ShanmugamV. Balasubramania
In the present work, an attempt was made to develop high temperature wear resistant hardfaced tools for friction stir welding (FSW) of commercial grade copper alloys. Hardfacing was applied on mild steel rod using chromium carbide forming powder by plasma transferred arc (PTA) hardfacing process and chromium carbide forming consumables by Shielded Metal Arc (SMA) hardfacing process. Commercially available tool material super high speed steel (SHSS) was also used to friction stir weld copper alloy for comparison purpose. From this investigation, it is found that the PTA hardfaced tool yielded defect free joints without tool wear compared with other tools. The optimum level of heat generation, formation of finer grains and higher hardness of stir zone are the main reasons for the superior tensile properties of the joints fabricated by PTA hardfaced chromium carbide tools.
- Effects of Bimodal and Monomodal SiC Particle on the Thermal Properties of
SiC-Particle-Dispersed Al-Matrix Composite Fabricated by SPS
Abstract: Effects of Bimodal and Monomodal SiC Particle on the Thermal Properties of SiC-Particle-Dispersed Al-Matrix Composite Fabricated by SPS
Author Kiyoshi MizuuchiKanryu InoueYasuyuki AgariMotohiro TanakaTakashi TakeuchiJun-ichi TaniMasakazu KawaharaYukio MakinoMikio It
Silicon carbide (SiC)-particle-dispersed-aluminum (Al) matrix composites were fabricated in continuous solid-liquid co-existent state by spark plasma sintering (SPS) process from the mixture of SiC powders, Al powders and Al-5mass%Si alloy powders. As the SiC powders, two kinds of powders, monomodal SiC powders of 109.8μm in diameter and a bimodal SiC powder mixture of 109.8μm and 14.3μm in diameter, were used. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 798K and 876K for 1.56ks during SPS process. No reaction at the interface between the SiC particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the monomodal composite decreased from 99.8% to 95.1% with increasing SiC volume fraction in a range of 55% and 65%, whereas that of the bimodal composite was 97% or higher than that in a SiC volume fraction range up to 70%. The thermal conductivity of the bimodal composite was higher than that of the monomodal composite in a SiC volume fraction range higher than 55%. The coefficient of thermal expansion of the composites falls in the upper line of Kerner’s model, indicating strong bonding between the SiC particle and the Al matrix in the composite.