The effect of joint shape geometry on the microstructural evolution, fracture toughness, and corrosion behavior of the welded joints of a Hadfield Steel

Anijdan

Asadian

2018

Effect of substrate temperature on microstructural evolution and hardenability of tungsten carbide coating produced by hot filament chemical vapor deposition (HFCVD) process was studied. Annealed sheets of 316L stainless steels were used as the substrate. HFCVD technique, with substrate temperatures of 400 and 500°C, was used to deposit tungsten carbide coating on these sheets. Field Emission Scanning Electron Microscope (FE‐SEM) was used to study the evolution of microstructure. X‐Ray Diffraction spectroscopy was used to analyze the phases formed and Raman spectroscopy was employed to differentiate molecular composition of the coatings. The amount of the porosity of the coatings was measured and Vickers hardness measurement was used for hardness assessment. Results show that the tungsten carbide coatings have a honeycomb structure and increasing the temperature of the substrate increases the amount of porosity of the coating. XRD results showed that 3 different crystalline structures containing W, WC, and W2C were formed in the coating deposited on the 316L stainless steel. Increasing the temperature of the deposition has increased the intensity of the peaks in the XRD results. Raman spectroscopy results indicated the presence of a carbon in the tungsten carbide coatings. Finally, microhardness of the tungsten carbide coating increases with increasing the temperature of the substrate.

Section: Resultsmentioning

confidence: 99%

The effect of substrate temperature on microstructural evolution and hardenability of tungsten carbide coating in hot filament chemical vapor deposition

Anijdan

Asadian

2018

“…In AgO‐C composite electrodes the extent of fluctuations in a corrosion potential plot per time has a direct relation to microscopic changes and the amount of porosity in the electrodes . This condition can be explained as followed, as the porosity of AgO‐C composite electrodes increases, the favorable conditions for localized corrosion is provided more and more . Also, it can be mentioned that after activation of electrochemical reaction in the corrosion cell, as soon as one pore in the AgO‐C composite electrodes is filled with corrosion products, another pore gets involved in the electrochemical reactions and results in release of the ions in the solution, which in turn shifts corrosion potential to more negative values.…”

Section: Resultsmentioning

confidence: 99%

A study on the effect of compositing silver oxide nanoparticles by carbon on the ‎electrochemical behavior and electronic properties of zinc‐silver oxide batteries ‎

Dezfuli

2018

In this study, the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide batteries have been investigated. For this purpose, firstly four silver oxide electrodes containing 5, 10, 15, and 20 wt% carbon powder were produced by powder metallurgy method. For the next step, all four silver oxide electrodes were sintered at 500°C for 10 minutes. Afterward and in order to investigate the microstructure, phase and elemental analysis of the electrodes were carried out using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X‐ray Diffraction (XRD), and Energy Dispersive Spectroscopy (EDS), respectively. Moreover, in order to investigate the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and electric discharge test in 1.4 wt%KOH electrolyte were carried out respectively. The microstructural observations revealed that increasing carbon content in the silver oxide electrodes results in increasing the apparent porosities in these electrodes. Investigating the phase and elemental analysis results showed that by increasing the content of carbon in the silver oxide electrode, the amount of Ag2O and AgO phases in this electrode reduces and also the extent of pure silver formation increases. Investigations on the results of electrochemical tests showed that increasing carbon content results in the reduction of corrosion resistance in silver oxide electrodes. Moreover, the results of electric discharge test revealed that the silver oxide electrode containing 10wt% carbon yields the highest energy efficiency in the zinc‐silver oxide batteries.

“…Overall, comparing the Nyquist curves for the two tungsten carbide coatings produced at the sub‐layer temperatures of 400°C and 500°C, it can be seen that the diameter of the half‐circle in the Nyquist curves for the coating deposited at 400°C is smaller. The half‐circle in the Nyquist curves is a sign of polarization resistance of the tungsten carbide . It is important to mention that the tungsten carbide coating produced at the sub‐layer temperature of 400°C contained lower amount of porosity compared to the tungsten carbide coating deposited at 500°C.…”

Section: Resultsmentioning

confidence: 99%

Effect of sub‐layer temperature during HFCVD process on morphology and corrosion behavior of tungsten carbide coating

Anijdan

Asadian

et al. 2018

WC coating was deposited on the polished and cleaned 316L stainless steel by Hot Filament Chemical Vapor Deposition (HFCVD) technique at 400°C and 500°C. Field Emission Gun Scanning Electron Microscope (FEG‐SEM) was used to study the corrosion morphology of the WC coatings. Energy dispersive spectroscopy (EDS) was used to analyze the chemical composition of the coatings. Coating porosity was measured by immersion in water. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to study the corrosion behavior of the coating in the solution of 1 mol/L H2SO4. Results showed that the WC coatings have a honeycomb microstructure where its porosity was increased at higher temperature of the sub‐layer. Also, the WC coating significantly increases the corrosion resistance of 316L stainless steel. And increasing the sub‐layer temperature in the HFCVD method reduces the corrosion resistance of the WC coating. Corrosion morphology was indicative of pitting corrosion of the WC coating.