List of Articles hot Corrosion

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  1 - Improving the Efficiency and Durability of Blast Furnace Air Tuyere Through Different Ceramic Coating Materials
  Hasan Bagheri Hasan Abadi Mohsen Hamedi
  Blast air tuyeres are one of the critical components of a blast furnace that are exposed to severe conditions caused by thermal shocks, mechanical erosion, hot chemical corrosion, wettability caused by penetration of molten cast iron, and cracks caused by the thermal cy More

  Blast air tuyeres are one of the critical components of a blast furnace that are exposed to severe conditions caused by thermal shocks, mechanical erosion, hot chemical corrosion, wettability caused by penetration of molten cast iron, and cracks caused by the thermal cycle. These factors decrease the lifetime of air tuyeres, causing unpredictable failure and costly production stoppages. The present study investigates the protection performance of three types of atmospheric plasma-sprayed ceramic coatings on air tuyeres against the harsh operating environment. As the substrate of air tuyeres, 99.95% pure copper is coated with Yttria Stabilized Zirconia YSZ8%, alumina-zirconia (AZ) and alumina-magnesia (AM). The performance of these three coatings was evaluated using mechanical wear and erosion tests, chemical hot corrosion tests, micro-hardness adhesion strength tests, and porosity measurements. Based on the results, AZ and AM coatings generally performed better than YSZ8% coating in all above-mentioned tests excluding the adhesion strength test. In the adhesion strength test, the AZ coating performance was found to be close to that of YSZ8% coating. Meanwhile, in the mechanical erosion and wear tests, the AM coating outperformed and underperformed the AZ coating, respectively. The porosity of AZ coating was also close to that of AM coating. Hence, it is expected that the blast air tuyere with AZ and AM coatings can offer better performance in blast furnace due to their superior metallurgical and mechanical properties. However, in practice, the AZ coating outperformed the AM coating in BF due to a three-fold increase in the lifecycle. Manuscript profile
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  2 - Electrochemical study on hot corrosion behavior of aluminide diffusion coating deposited on inconel 713C superalloy
  Esmaeil Taheri Mehdi Verdian
  In this study, the hot corrosion resistance of diffusion aluminide coating on Inconel 713C was investigated using electrochemical techniques. In this regard, potentiodynamic polarization tests were performed at 750 °C in two kinds of molten salts. The former contain More

  In this study, the hot corrosion resistance of diffusion aluminide coating on Inconel 713C was investigated using electrochemical techniques. In this regard, potentiodynamic polarization tests were performed at 750 °C in two kinds of molten salts. The former contained 70% sodium sulphate and 30% sodium chloride. The latter was composed of 70% sodium sulphate, 25% sodium chloride and 5% vanadium pentoxide. The phase composition and microstructure of coatings and corrosion products were investigated using XRD and SEM-EDS techniques. The results showed that in the presence of vanadium, the protection efficiency of coatings increased and a current-independent region was observed in anodic polarization curve. Here, a compact corrosion product layer was seen. In absence of vanadium, both coated and uncoated samples exhibited similar corrosion rates. However, in comparison to vanadium-containing environment, all samples showed lower corrosion rate. In this case, the coatings exhibited active anodic behavior. The corrosion products were porous and discontinuous in vanadium free environment. Manuscript profile
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  3 - The effect of Pt on type II hot corrosion behavior of Si-aluminide coatings with lower silicon than the critical amount
  Seyed Amir Azarmehr kourosh shirvani Jozdani
  In this paper, the effect of adding a low amount of platinum to slurry Si-modified aluminide coatings containing silicon less than the amount required to provide complete protection in these coatings is investigated. In addition to the coatings characterization, the rol More

  In this paper, the effect of adding a low amount of platinum to slurry Si-modified aluminide coatings containing silicon less than the amount required to provide complete protection in these coatings is investigated. In addition to the coatings characterization, the role of platinum on the type II hot corrosion behavior of coatings has been discussed. To create silicon and silicon-platinum aluminide coatings, a slurry silicoaluminzing method was applied to samples of Ni-base superalloy GTD-111 specimens, which was previously Pt-electroplated on some of them with a thickness of 2 μm. The amount of silicon in the slurry was 10% by weight relative to total solid of the slurry, so that the amount of silicon in the coating is less than the critical amount required for complete protection. The type II hot corrosion test was carried out using a furnace method with Na2SO4-60mol% V2O5 at 700 °C. After 20 hours of hot corrosion, Al2O3 protective oxide and non-protective oxide NiAl2O4 were detected in silicon-platinum- and silicon-aluminide coatings, respectively. In the absence of platinum, the Ni3V2O8 phase was also found to be a product of NiO and NiAl2O4 dissolution in type-II hot corrosion condition. At the end of the 80-hour hot corrosion, unlike the silicon-aluminide coating, silicon remained in the silicon-platinum-aluminide coating structure. Manuscript profile
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  4 - Developing in situ nano forsterite by adding micro silica and silicon and studying the role of ferrosilicon on physical and mechanical properties of magnesium forsterite carbon
  Marjan Monshi Ahmad Monshi
  When using Magnesia-Carbon refractories in slag line (1600 C) oxidation produces porosity and corrosion. In this research, micro silica is added to produce in situ nano forsterite inside the brick and act as a binding between MgO grains. This increases Brazilian (streng More

  When using Magnesia-Carbon refractories in slag line (1600 C) oxidation produces porosity and corrosion. In this research, micro silica is added to produce in situ nano forsterite inside the brick and act as a binding between MgO grains. This increases Brazilian (strength resistant to crack growth) and lowers chemical potential of silica between brick-slag and decreases diffusion of slag. 3% silicon (anti-oxidant), 1-10 % micro silica and in 2nd series of samples ferrosilicon was added. XRD showed increase of forsterite formation with ferrosilicon. Physical and mechanical properties after tempering at 250 C and sintering at 1600 C were studied at this time. Strength and crack resistance improved. Modified Scherer Equation which showed crystal size, measured crystals of forsterite as 32 nm. Ratio of Slopes Method used to calculated 10, 14 and 24 % forsterite respectively at 3, 5 and 10 % micro silica addition to yhe bricks. It shows that increase in silica, increase potencial of forsterite formation. Manuscript profile
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  5 - Investigation of the Wear Corrosion and Hot Corrosion Properties of Alumina Coating Applied on Steel Substrate via High Velocity Oxy-Fuel Method
  seyed Ali Khosravifard Amirhosein Yaghtin Amin Akhbarizadeh Alireza Araghi
  In the present work, Alumina coating with an approximate thickness of 240 µm was applied via high velocity oxy-fuel (HVOF) method on a 4340 hot-work tool steel substrate. The morphology of the coating and the influences of the corrosive medium which contained hydr More

  In the present work, Alumina coating with an approximate thickness of 240 µm was applied via high velocity oxy-fuel (HVOF) method on a 4340 hot-work tool steel substrate. The morphology of the coating and the influences of the corrosive medium which contained hydro-chloric acid (5-15 vol.%) were studied using scanning electron microscope (SEM). Afterwards, the wear behavior of the coatings in dry and acidic wet environments were studied using a pin-on-disk wear apparatus and the wear mechanism was analyzed through SEM studies. The results of the wear tests showed that the wear rate in the 5% acidic medium was approximately the same as that of the dry test. Furthermore, the results showed that increasing the concentration of acid in the wear medium (up to 15%), leads to a continuous increase of the wear rate which was ascribed to increased corrosion rate. The dominant wear mechanism in all the tested situations was determined as sticking wear. As the wear rate increased, the wear surfaces showed increased roughness. Finally, hot corrosion experiments were carried on the coated specimens at the temperature of 880 ˚C. At this condition, the coating lasted for about 460 hours. Manuscript profile