Effect of electroplating time on microstructure, corrosion and wear behaviour of Ni-P-W-TiO2 coating

Ni-P-W-TiO2 coating has been deposited on the AISI 304L steel substrate using the electroplating method. Electroplating has been performed at 30, 45, and 60 min, and the effect of electroplating time on microstructure, corrosion and wear behaviour has been investigated. The coatings have been characterized by use of scanning electron microscopy (SEM). In order to investigate corrosion resistance, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests have been used in 3.5% of NaCl aqueous solution. A pin on disk test has been used to test the wear resistance of uncoated and coated samples. Sample micro-hardness has also been measured by the Vickers hardness test. Examination of the microstructure has shown that the best time for deposition is 45 min. The results of potentiodynamic polarization and electrochemical impedance spectroscopy tests are also consistent with microscopic images, and the results have shown that the coating created within 45 min has the highest corrosion resistance (7058 Ω.cm2) compared to coated sample within 30 (4142 Ω.cm2) and 60 (3059 Ω.cm2) minutes. Also, the results of the wear test and micro-hardness have shown that composite coating formed within 45 minutes has the highest wear resistance and micro-hardness (677 Vickers) compared to coated sample within 30 (257 Vickers) and 60 (638 Vickers) minutes

Effect of electroplating temperature on microstructure, corrosion, and wear behavior of Ni-P-W-TiO2 coating

108-115Nickel-phosphorus-titanium oxide coating is fabricated on the AISI 304L steel substrate using the electroplating method. Electroplating is performed at temperatures of 55°C, 60°C, and 65°C, and the effect of electroplating temperature on microstructure, corrosion behavior, and wear behavior is investigated. The coatings are characterized using scanning electron microscopy (SEM). In order to investigate corrosion resistance, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests are performed in a 3.5% NaCl aqueous solution. A pin-on-disk test is employed to investigate the wear resistance of uncoated and coated samples. Sample micro-hardness is also measured by the Vickers hardness test. The results of potentiodynamic polarization and EIS tests show that the coating created at the temperature of 60°C has the highest corrosion resistance (7058 Ω.cm2) compared with the samples coated at temperatures of 55°C (2115 Ω.cm2) and 65°C (2289 Ω.cm2). Moreover, the results of the wear and micro-hardness test show that the composite coating formed at the temperature of 60°C has the highest wear resistance and micro-hardness (677 Vickers) compared with the samples coated at temperatures of 55°C (411 Vickers) and 65°C (536 Vickers)

Effect of electroplating temperature on microstructure, corrosion and wear behavior of Ni-P-W-TiO2 coating

Nickel-phosphorus-titanium  oxide  coating  was  fabricated  on  the  AISI  304L  steel  substrate  using  the  electroplating  method.  Electroplating  was  performed  at  temperatures  of  55,  60  and  65  °C,  and  the  effect  of  electroplating  temperature  on  microstructure,  corrosion  behavior,  and  wear  behavior  was  investigated.  The  coatings  were  characterized  by  use  of  scanning  electron  microscopy  (SEM).  In  order  to  investigate  corrosion  resistance,  potentiodynamic  polarization  and  electrochemical  impedance  spectroscopy  (EIS)  tests  were  performed  in  3.5%  of  NaCl  aqueous  solution.  A  pin  on  disk  test  was  employed  to  investigate  the  wear  resistance  of  uncoated  and  coated  samples.  Sample  micro-hardness  was  also  measured  by  the  Vickers  hardness  test.  The  results  of  potentiodynamic  polarization  and  electrochemical  impedance  spectroscopy  tests  results  showed  that  the  coating  created  at  temperature  of  60  °C  had  the  highest  corrosion  resistance  (7058  Ω.cm2)  compared  to  coated  sample  at  temperature  of  55  °C  (2115  Ω.cm2)  and  65  °C  (2289  Ω.cm2).  Also,  the  results  of  the  wear  and  micro-hardness  test  showed  that  composite  coating  formed  at  temperature  of  60  °C  had  the  highest  wear  resistance  and  micro-hardness  (677  Vickers)  compared  to  coated  sample  at  temperature  of  55  °C  (411  Vickers)  and  65  °C  (536  Vickers)

Evaluation of electrical conductivity activation energy of manganese coated Fe-17%Cr ferritic stainless steel

From an electrical conductivity perspective, only chromia forming alloys can be considered as candidates for interconnect application in solid oxide fuel cell. In this research, AISI 430 ferritic stainless steel was coated in a Mn-base pack mixture by pack cementation method. Electrical conductivity of the coated coupons was measured as a function of temperature by oxidizing the samples from room temperature to 800ºC. Also the electrical conductivity has been studied as a function of oxidation time during isothermal oxidation at 800ºC. Results showed the increase of temperature caused to the decrease of electrical conductivity and also, the coating layer transformed to manganese spinels during isothermal oxidation. The spinel compositions ameliorated the electrical conductivity activation energy of coated coupons (0.029 eV) compared to uncoated ones (0.031 eV)

Reduced parabolic rate constant at presence of Mn3O4 and MnFe2O4

Long-term stability and oxidation resistance of AISI 430 ferritic stainless steel which is employed as an interconnect in solid oxide fuel cells (SOFCs) for intermediate temperature operation, can be ameliorated with a protective coating layer. In this study the pack cementation method was employed to coat AISI 430 ferritic stainless steel. Isothermal oxidation and cyclic oxidation were applied to evaluate the parabolic rate constant. Spinels forming (Mn3O4 and MnFe2O4) during oxidation improves oxidation resistance. The coated samples demonstrated lower kp in each test and it indicates that the coating layer could have acted as a mass barrier against the outward diffusion of cations specially Cr

Investigation on parabolic rate constant in presence of MnCo2O4, CoCr2O4, CoFe2O4 and Co3O4 coatings at 700ºC

Oxidation resistance of solid oxide fuel cells interconnects can be ameliorated by use of a protective, effective, relatively dense and well adherent spinel coating. In this study the pack cementation method was employed to coat AISI 430 ferritic stainless steel. Isothermal oxidation and cyclic oxidation were applied at 700ºC to evaluate the parabolic rate constant (kp). The formation of MnCo2O4, CoCr2O4, CoFe2O4 and Co3O4 Spinels during oxidation improved oxidation resistance. The coated samples demonstrated lower kp in each test and it indicate that the coating layer has acted as a mass barrier against the outward diffusion of cations specially Cr

Electrical conductivity of interconnects in presence of two manganese spinel coatings

Intermediate temperature solid oxide fuel cells(SOFCs) allow the use of ferritic stainless steel interconnect. The bare plates can not remain the electrical conductivity after long term oxidation. The purpose of this work was to investigate the electrical conductivity of AISI 430 stainless steel which was coated in a Co-base pack mixture by pack cementation method. Coated samples were characterized using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). Electrical conductivity of the coated substrates was tested as a function of temperature by annealing the samples from room temperature to 800ºC. Also electrical conductivity has been investigated as a function of oxidation time during isothermal oxidation at 800ºC. Results showed the increase of temperature caused to the decrease of electrical conductivity and also, X-ray diffraction pattern revealed, that the coating layer converted to Mn3O4 and MnFe2O4 spinels during isothermal oxidation. These spinels improved electrical conductivity of coated substrates (54.7 S.cm-1) compared to uncoated substrates (27.7 S.cm-1) after 200h oxidation at 800ºC

Study of parabolic rate constant for coated AISI 430 steel with Mn₃O₄ and MnFe₂O₄spinels

314-320The oxidation resistance of AISI 430 ferritic stainless steels which are used as interconnects in solid oxide fuel cells (SOFCs) for the intermediate temperature operation can be improved with a protective coating layer. In this study, the pack cementation method is employed to coat AISI 430 ferritic stainless steel. Isothermal oxidation, cyclic oxidation and oxidation at different temperatures (600-900°C) are applied to evaluate the parabolic rate constant. The coated samples demonstrated lower parabolic rate constant (kp) in each test and it indicates that the coating layer has acted as a mass barrier against the outward diffusion of cations specially chromium. XRD analysis revealed that the formation of Mn3O4 and MnFe2O4 spinels during oxidation caused to the improvement of the oxidation resistance

Studies on electrical resistance activation energy in presence of cobalt spinels

The formation of oxide layer on the surface of used interconnects in solid oxide fuel cells (SOFCs), decrease the electrical conductivity and therefore energy losses can be occurred. The electrical conductivity of ferritic stainless steels can be improved by applying a protective/ conductive layer. In this study pack cementation method was employed to coat the AISI 430 ferritic stainless steel. Isothermal oxidation was applied at 700ºC for 200 h to evaluate the area specific resistance (ASR) values. Electrical resistance activation energy was evaluated by use of previous consequences. The formation of MnCo2O4, CoCr2O4, CoFe2O4 and Co3O4 spinels during oxidation improved oxidation resistance and electrical conductivity. Results showed that the activation energy decreased when the temperature decreased and the coated samples electrical resistance activation energy (0.026eV) was lower than uncoated ones (0.033eV)

Effect of electroplating time on microstructure, corrosion and wear behaviour of Ni-P-W-TiO2 coating

76-84Ni-P-W-TiO2 coating has been deposited on the AISI 304L steel substrate using the electroplating method. Electroplating has been performed at 30, 45, and 60 min, and the effect of electroplating time on microstructure, corrosion and wear behaviour has been investigated. The coatings have been characterized by use of scanning electron microscopy (SEM). In order to investigate corrosion resistance, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests have been used in 3.5% of NaCl aqueous solution. A pin on disk test has been used to test the wear resistance of uncoated and coated samples. Sample micro-hardness has also been measured by the Vickers hardness test. Examination of the microstructure has shown that the best time for deposition is 45 min. The results of potentiodynamic polarization and electrochemical impedance spectroscopy tests are also consistent with microscopic images, and the results have shown that the coating created within 45 min has the highest corrosion resistance (7058 Ω.cm2) compared to coated sample within 30 (4142 Ω.cm2) and 60 (3059 Ω.cm2) minutes. Also, the results of the wear test and micro-hardness have shown that composite coating formed within 45 minutes has the highest wear resistance and micro-hardness (677 Vickers) compared to coated sample within 30 (257 Vickers) and 60 (638 Vickers) minutes