ارزیابی خواص پوشش محافظ ایجاد شده روی تیتانیم توسط فرآیند اکسیداسیون الکترولیتی پلاسمایی در الکترولیت حاوی پتاسیم فسفات

نوع مقاله: مقاله پژوهشی

نویسندگان

1 پژوهشکده نانو و مواد پیشرفته، پژوهشگاه مواد و انرژی

2 هیات علمی پژوهشگاه مواد و انرژی

چکیده

پوشش­های محافظ اکسید تیتانیم به روش اکسیداسیون الکترولیتی پلاسمایی روی زیرلایه تیتانیم خالص تجاری در چگالی جریان A/cm2 15/0 و الکترولیت حاوی g/L 15-5 پتاسیم فسفات برای مدت زمان s 600-120 ایجاد شدند. تاثیر زمان اکسیداسیون و غلظت الکترولیت روی مورفولوژی سطح، ضخامت، زبری، تخلخل نسبی، توزیع حفرات، ریزساختار و رفتار خوردگی مورد ارزیابی قرار گرفت. بررسی تغییرات ولتاژ- زمان مشخص ساخت که افزایش غلظت الکترولیت تا g/L 15، سبب تسریع فرایند جرقه­زنی شده و ولتاژ شکست را از V 593 به V 516 کاهش داده است. ارزیابی مورفولوژی سطحی نشان داد که حفرات سطحی در فواصل دورتری از یکدیگر ایجاد و برآمدگی­های اطراف حفرات نمایان­تر شده است. با گذشت زمان پوشش­دهی تا s 600 ضخامت و زبری سطح لایه اکسیدی افزایش یافت و با توجه به تخلخل 11%  سطح پوشش، مجموع تعداد حفرات با قطر بیش از µm 1 به 18% کل حفرات سطحی رسید. بررسی رفتار خوردگی مشخص ساخت که ضخامت µm 3/0 2±/8 و تراکم سطحی کم حفرات، مقاومت به خوردگی نمونه پوشش­دهی شده در غلظت g/L 15 پتاسیم فسفات را تا  kΩ.cm21670 افزایش داده است.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluating the Properties of Protective Coating Prepared on Titanium Using Plasma Electrolytic Oxidation in Potassium Phosphate Electrolyte

نویسندگان [English]

  • Amin Hoseini 1
  • Benyamin Yarmand 1
  • Alireza Kolahi 2
1 Nanoscience and Advanced Materials Institute, Materials and Energy Research Center
2 Academic staff of the Institute of Materials and Energy Research Center
چکیده [English]

Titanium oxide coatings were prepared on commercially pure titanium substrates using plasma electrolytic oxidation process under current density of 0.15 A/cm2 in electrolyte containing 5-15 g/L potassium phosphate for period of 120-600 s. The effects of oxidation time and electrolyte concentration on surface morphology, thickness, roughness, relative porosity, pores size distribution, microstructure and corrosion behavior were evaluated. Investigation of voltage-time variations showed that increasing the electrolyte concentration up to 15 g/l caused an acceleration of microdischarge events and reduced the breakdown voltage from 593 V to 516 V. Morphological observations revealed that the pores were located at long distances and protuberances around the pores were more prominent. By increasing the oxidation time to 600 s, the thickness and roughness of the coatings increased, and due to the presence of 11% porosity of the coating surface, the total number of pores with diameters greater than 1 μm to 18% of the total surface pores reached. Investigation of the corrosion behavior revealed that the thickness of 8.2 ± 0.3 μm and low porosity, increased the corrosion resistance of the sample coated in the concentration of 15 g/L of potassium phosphate up to 1670 kΩ.cm2.

کلیدواژه‌ها [English]

  • Plasma electrolytic oxidation
  • Titanium
  • Potassium phosphate

1.      Shokouhfar, M., et al., Preparation of ceramic coating on Ti substrate by plasma electrolytic oxidation in different electrolytes and evaluation of its corrosion resistance: Part II. Applied Surface Science, 2012. 258(7): p. 2416-2423.

2.      Khan, R., etal., Influence of current density and electrolyte concentration on DC PEO titania coatings. Surface Engineering, 2014. 30(2): p. 102-108.

3.      Lv, G., et al., Characteristic of ceramic coatings on aluminum by plasma electrolytic oxidation in silicate and

 

         phosphate electrolyte. Applied Surface Science, 2006. 253(5): p. 2947-2952.

4.      Aliofkhazraei, M., et al., Effect of cerium ion addition on corrosion and wear characteristics of plasma electrolytic oxidation coating of CP-Ti. Protection of Metals and Physical Chemistry of Surfaces, 2016. 52(6): p. 1093-1099.

5.      Yerokhin, A., et al., Discharge characterization in plasma electrolytic oxidation of aluminium. Journal of Physics D: Applied Physics, 2003. 36(17): p. 2110.

6.      Dehnavi, V., et al., PRODUCTION OF CERAMIC COATINGS ON AA6061 ALUMINUM ALLOY USING PLASMA ELECTROLYTIC OXIDATION. Coatings for Corrosion and Wear-resistance Applications, 2013.

7.      Moon, S. and Y. Jeong, Generation mechanism of microdischarges during plasma electrolytic oxidation of Al in aqueous solutions. Corrosion Science, 2009. 51(7): p. 1506-1512.

8.      Dehnavi, V., Surface modification of aluminum alloys by plasma electrolytic oxidation. 2014.

9.      Khan, R.H., A. Yerokhin, and A. Matthews, Structural characteristics and residual stresses in oxide films produced on Ti by pulsed unipolar plasma electrolytic oxidation. Philosophical Magazine, 2008. 88(6): p. 795-807.

10.    Gowtham, S., T. Arunnellaiappan, and N. Rameshbabu, An investigation on pulsed DC plasma electrolytic oxidation of cp-Ti and its corrosion behaviour in simulated body fluid. Surface and Coatings Technology, 2016. 301: p. 63-73.

11.    Yangi, Y. and H. Wu, Effects of current density on microstructure of titania coatings by micro-arc oxidation. Journal of Materials Science & Technology, 2012. 28(4): p. 321-324.

12.    Stojadinović, S., et al., Characterization of the plasma electrolytic oxidation of titanium in sodium metasilicate. Applied Surface Science, 2013. 265: p. 226-233.

13.    Erfanifar, E., et al., Growth kinetics and morphology of microarc oxidation coating on titanium. Surface and Coatings Technology, 2017. 315: p. 567-576.

14.    Venkateswarlu, K., et al., Role of electrolyte chemistry on electronic and in vitro electrochemical properties of micro-arc oxidized titania films on CpTi. Electrochimica Acta, 2013. 105: p. 468-480.

15.    Adeleke, S., A. Bushroa, and I. Sopyan, Characteristic Features of Plasma Electrolytic Treated Layers in Na 3 PO 4 Solution. Procedia Engineering, 2017. 184: p. 732-736.

16.    Dehnavi, V., et al., Corrosion properties of plasma electrolytic oxidation coatings on an aluminium alloy–The effect of the PEO process stage. Materials Chemistry and Physics, 2015. 161: p. 49-58.

17.    Sarbishei, S., M.A.F. Sani, and M.R. Mohammadi, Effects of alumina nanoparticles concentration on microstructure and corrosion behavior of coatings formed on titanium substrate via PEO process. Ceramics International, 2016. 42(7): p. 8789-8797.

18.    Shin, K.R., Y.G. Ko, and D.H. Shin, Effect of electrolyte on surface properties of pure titanium coated by plasma electrolytic oxidation. Journal of Alloys and Compounds, 2011. 509: p. S478-S481.

19.    Dehnavi, V., et al., Phase transformation in plasma electrolytic oxidation coatings on 6061 aluminum alloy. Surface and Coatings Technology, 2014. 251: p. 106-114.

20.    Chang, L., Growth regularity of ceramic coating on magnesium alloy by plasma electrolytic oxidation. Journal of Alloys and Compounds, 2009. 468(1): p. 462-465.

21.    Ono, S., et al., Effect of Electrolyte Concentration on the Structure and Corrosion Resistance of Anodic Films Formed on Magnesium through Plasma Electrolytic Oxidation. Electrochimica Acta, 2017. 240: p. 415-423.

22.    Hariprasad, S., et al., Role of electrolyte additives on in-vitro corrosion behavior of DC plasma electrolytic oxidization coatings formed on Cp-Ti. Surface and Coatings Technology, 2016. 292: p. 20-29.

23.    Lv, G.-H., et al., Investigation of plasma electrolytic oxidation process on AZ91D magnesium alloy. Current Applied Physics, 2009. 9(1): p. 126-130.