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Modification of Microstructure and Surface Properties of Ti-6Al-4V Alloy by MoSi2 Particles Using Micro-Arc Oxidation Process

Kadhim Nawar Fahem, Haleem Ali Hubi, Awad Samir Hamid

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

374--384

EN

As an effective surface modification technique, micro-arc oxidation (MAO) is now widely used to improve the hardness and wear resistance of Ti and its alloys by low-cost and thick ceramic coatings. In this study, MoSi2 – modified ceramic coatings were deposited on Ti–6Al–4V alloy (340 HV) by MAO using an aqueous solution of (Na2SiO3),(NaPO3)6 and (NaOH) and MoSi2 particles. MoSi2 particles (3, 5, and 7 g/l) from wastes of furnaces electrodes were introduced into the electrolyte to improve the microstructure and surface properties of Ti-6Al-4V alloys. A scanning electron microscope (SEM), dispersive spectroscopy (EDS), X-ray diffraction (XRD), and mechanical tests (microhardness and wear) were used to identify the coating properties, morphologies, and phases. The findings showed that the addition of (5g/l) MoSi2 increased the thickness and hardness of MAO coatings from (19.08µm) and (910 HV) to (33.12µm) and (1260 HV), respectively. Also, the wear resistance by means of weight losses of uncoated alloys enhanced by (68 %) and (100%) after MAO and (5g/l) MoSi2 modified-MAO coatings, respectively. Results of this work will promote future works in using of industrial wastes in surface engineering of Ti-6Al-4V alloys by MAO technique for wear resistance applications.

2

Fabrication and characterisation of porous coatings obtained by plasma electrolytic oxidation

Rokosz K., Hryniewicz T., Raaen S., Malorny W.

Journal of Mechanical and Energy Engineering

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2017

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Vol. 1, No 1

23--30

EN

In the paper, characteristics of porous coatings enriched in copper on pure Titanium and its alloys (NiTi, Ti6Al4V, TNZ, Ti2448) as well as on niobium obtained by Plasma Electrolytic Oxidation (PEO) in electrolyte containing H3PO4 within Cu(NO3)2, are presented. All obtained surfaces of PEO coatings have different shapes and diameters of pores. The binding energies of main peaks for titanium Ti2p3/2, niobium Nb3d5/2, zirconium Zr3d5/2, phosphorus (P2p) and oxygen (O1s) suggest the presence of titanium Ti4+, niobium Nb5+ and zirconium Zrx+ (x≤2) as well as PO4 3–.

3

SEM and EDS Characterization of Porous Coatings Obtained On Titaniumby Plasma Electrolytic Oxidation in Electrolyte Containing Concentrated Phosphoric Acid with Zinc Nitrate

Rokosz K., Hryniewicz T., Pietrzak K., Malorny W.

Advances in Materials Science

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2017

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Vol. 17, nr 2(52)

41--54

EN

The SEM and EDS results of porous coatings formed on pure titanium by Plasma Electrolytic Oxidation (Micro Arc Oxidation) under DC regime of voltage in the electrolytes containing of 500 g zinc nitrate Zn(NO3)2·6H2O in 1000 mL of concentrated phosphoric acid H3PO4 at three voltages, i.e. 450 V, 550 V, 650 V for 3 minutes, are presented. The PEO coatings with pores, which have different shapes and the diameters, consist mainly of phosphorus, titanium and zinc. The maximum of zinc-to-phosphorus (Zn/P) ratio was found for treatment at 650 V and it equals 0.43 (wt%) | 0.20 (at%), while the minimum of that coefficient was recorded for the voltage of 450 V and equaling 0.26 (wt%) | 0.12 (at%). Performed studies have shown a possible way to form the porous coatings enriched with zinc by Plasma Electrolytic Oxidation in electrolyte containing concentrated phosphoric acid H3PO4 with zinc nitrate Zn(NO3)2·6H2O.

4

Fabrication and characterisation of porous, calcium enriched coatings on titanium after plasma electrolytic oxidation under DC regime

Rokosz K., Hryniewicz T., Pietrzak K., Sadlak P., Valíček J.

Advances in Materials Science

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2017

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Vol. 17, nr 4(54)

55--67

EN

The purpose of this work is to produce and characterize (chemical composition and roughness parameters) porous coatings enriched in calcium and phosphorus on the titanium (CP Titanium Grade 2) by plasma electrolytic oxidation. As an electrolyte, a mixture of phosphoric acid H3PO4 and calcium nitrate Ca(NO3)2·4H2O was used. Based on obtained EDS and roughness results of PEO coatings, the effect of PEO voltages on the chemical composition and surface roughness of porous coatings was determined. With voltage increasing from 450 V to 650 V, the calcium in PEO coatings obtained in freshly prepared electrolyte was also found to increase. In addition, the Ca/P ratio increased linearly with voltage increasing according to the formula Ca/P = 0.035·U+0.176 (by wt%) and Ca/P = 0.03·U+0.13 (by at%). It was also noticed that the surface roughness increases with the voltage increasing, what is related to the change in coating porosity, i.e. the higher is the surface roughness, the bigger are pores sizes obtained.

5

Characteristic of MAO coatings formed on CuAl2 in-situ reinforced Aluminum Matrix Composites

Mafouz D. I., Paksoy A. H., Muhaffel F., Tazegul T., Cimenoglu H.

Archives of Materials Science and Engineering

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2016

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Vol. 79, nr 2

60--63

EN

Purpose: The aim of this study was to examine the structural and mechanical properties of coatings formed on CuAl2 in-situ reinforced aluminium matrix composites (AMCs) by micro arc oxidation (MAO) process. AMC, which were fabricated by powder metallurgy method upon addition of copper powder into aluminium powder at different percentages (0%, 15 wt.% and 30 wt.%), were exposed to MAO after sintering at 550°C for 6 h. During sintering process CuAl2 type intermetallic was precipitated in the microstructure of copper containing compacts. MAO caused covering of the surfaces of AMCs with an oxide layer mostly consisting of mullite and alumina. Mechanical performance of the coatings were determined by hardness measurements and wear tests. In summary, the oxide layers formed on the AMCs exhibit a reduction in hardness and tribological performance with increasing copper content of the AMC.

6

Energy-dispersive X-Ray spectroscopy mapping of porous coatings obtained on Titanium by plasma electrolytic oxidation in a solution containing concentrated phosphoric acid with copper nitrate

Rokosz K., Hryniewicz T., Dudek Ł., Schütz A., Heeg J., Wienecke M.

Advances in Materials Science

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2016

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Vol. 16, nr 3(49)

15--25

EN

The SEM and EDS study results of coatings obtained on titanium by Plasma Electrolytic Oxidation (PEO) in the electrolytes containing of 600 g copper nitrate in 1 liter of concentrated phosphoric acid at 450 V for 1 and 3 minutes, are presented. The obtained coatings are porous and consist mainly of phosphorus within titanium and copper. It was found that the time of PEO oxidation has impact on the chemical composition of the coatings. The longer time of PEO treatment, the higher amount of copper inside coating. The PEO oxidation of titanium for 1 minute has resulted in the creation of coating, on which 3 phases where found, which contained up to 13.4 wt% (9 at%) of copper inside the phosphate structure. In case of 1 minute PEO treatment of titanium, the 2 phases were found, which contained up to 13 wt% (8 at%) of copper inside the phosphate structure. The copper-to-phosphorus ratios after 1 minute processing belong to the range from 0.28 by wt% (0.14 by at%) to 0.47 by wt% (0.23 by at%), while after 3 minutes the same ratios belong to the range from 0.27 by wt% (0.13 by at%) to 0.35 by wt% (0.17 by at%). In summary, it should be stated that the higher amounts of phosphorus and copper were recorded on titanium after PEO oxidation for 3 minutes than these after 1 minute.

7

Characterization of coatings created on selected Titanium alloys by Plasma Electrolytic Oxidation

Rokosz K., Hryniewicz T., Malorny W.

Advances in Materials Science

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2016

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Vol. 16, nr 1(47)

5--16

EN

The SEM and EDS results of coatings obtained on pure niobium and titanium alloys (NiTi and Ti6Al4V) by Plasma Electrolytic Oxidation in the electrolytes containing of 300 g and 600 g copper nitrate in 1 litre of concentrated phosphoric acid at 450 V for 3 minutes, are presented. The obtained coatings are porous and consist mainly of phosphorus within titanium and copper. For each coating, the Cu/P ratios were calculated. The maximum of that coefficient was found for niobium and Ti6Al4V alloy oxidised in the electrolyte containing 600 g of Cu(NO3)2 in 1 dm3 of H3PO4 and equaling to 0.22 (wt%) | 0.11 (at%). The minimum of Cu/P ratio was recorded for NiTi and Ti6Al4V alloys oxidised by PEO in electrolyte consisting of 300 g of copper nitrate in 1 dm3 of concentrated phosphoric acid and equals to 0.12 (wt%) | 0.06 (at%). The middle value of that ratio was recorded for NiTi and it equals to 0.16 (wt%) | 0.08 (at%).

8

SEM and EDS analysis of nitinol surfaces treated by Plasma Electrolytic Oxidation

Rokosz K., Hryniewicz T., Dudek Ł., Malorny W.

Advances in Materials Science

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2015

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Vol. 15, nr 3(45)

41--47

EN

In the paper, the surface layers formed on nickel-titanium alloy during Plasma Electrolytic Oxidation (PEO), known also as Micro Arc Oxidation (MAO), are described. The mixture of phosphoric acid and copper nitrate as the electrolyte for all plasma electrochemical processes was used. Nitinol biomaterial was used for the studies. All the experiments were performed under the voltage of 450 V and current density of 0.3 A/dm2. The main purpose of the studies was to achieve the highest amount of copper in the surface layer versus amount of the copper nitrate in phosphoric acid. The highest copper concentration was found in the surface layer after the PEO treatment in the electrolyte consisting of 150g Cu(NO3)2 in 0.5 dm3 H3PO4. The worst results, in case of the amount of copper in the NiTi surface layer, were recorded after oxidizing in the solution with 5 g Cu(NO3)2.

9

Characterization and wear properties of carbon nanotubes incorporated ceramic coatings on Ti6Al4V and Ti6Al7Nb alloys

Yazıcı S.K., Muhaffel F., Yurekturk Y., Baydoğan M.

Journal of Achievements in Materials and Manufacturing Engineering

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2014

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Vol. 65, nr 2

73--78

EN

Purpose: of this paper is characterization and wear properties of carbon nanotubes incorporated ceramic coatings on Ti6Al4V and Ti6Al7Nb alloys. Design/methodology/approach: Carbon nanotubes (CNTs) incorporated ceramic coatings were fabricated by micro arc oxidation (MAO) method to improve the tribological performance of Ti6Al4V and Ti6Al7Nb alloys for wear resistant applications. Titania and CNTs incorporated titania coatings were formed on Ti6Al4V and Ti6Al7Nb alloys via MAO process. Surface and cross-sectional morphology, phase composition, thickness and roughness of the ceramic coatings were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometer. Findings: Wear behavior of bare titanium alloys and those of their oxidized surfaces (with and without CNTs addition) were evaluated by reciprocating wear test against 100Cr6 steel ball at dry sliding condition. XRD analyses of the oxidized samples demonstrated that coatings were consisted mainly of rutile and aluminum titanate. Surface morphologies of the coatings revealed that CNTs addition into the electrolyte led to generation of less porous, flat regions surrounded by relatively irregular-shaped pores on the surface of the coatings. Wear rate of CNTs incorporated coatings was decreased significantly compared to coatings generated without CNTs addition. Research limitations/implications: CNTs addition into the base electrolyte sharply decreases wear rate of both alloys, and there is no significant difference between the wear rates of Ti6Al4V and Ti6Al7Nb alloys oxidized in CNTs added electrolyte. Originality/value:Titanium and its alloys are attracting a great deal of attention especially in automotive and aerospace industries. However, titanium-based materials tend to have insufficient wear resistance in abrasive conditions. In an attempt to overcome this limitation, carbon nanotubes (CNTs) incorporated ceramic coatings were fabricated.

10

Preparation and characterization of hydrothermally treated hydroxyapatite containing titania layer on commercially pure titanium

Teker D., Muhaffel F., Cimenoglu H.

Archives of Materials Science and Engineering

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2014

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Vol. 68, nr 1

5--9

EN

Purpose: To investigate the effect of hydrothermal treatment (HT) on bioactivity of micro arc oxidized (MAO) and MAO/) commercially pure titanium (Cp-Ti). Design/methodology/approach: Cp-Ti (Grade IV) samples were oxidized in order to generate titania layer via micro arc oxidation (MAO) process. The samples were treated at 400 V for 5 minutes in a calcium acetate hydrate and disodium hydrogen phosphate anhydrous containing electrolyte. Subsequently, hydrothermal treatment (HT) was applied on oxidized surface in an autoclave with a water solution whose pH adjusted to 11.0-11.5 by adding NaOH, at 200 and 230°C for 2.5, 5 and 10 h and cooled in the autoclave to achieve improved bioactivity behaviour. The bioactivity tests were employed by soaking the samples in a 1.5X simulated body fluid (SBF) to characterize biological response of treated surfaces. The mean elemental composition, surface and cross-sectional morphology, phase composition and surface roughness were examined by energy dispersive spectrometer (EDS) equipped scanning electron microscopy (SEM), X-ray diffractometer (XRD) and profilometer, respectively. Findings: It is found that after MAO+HT process, the surface roughness of the samples was reduced due to the homogeneous distribution of HA agglomerates. The improved surface properties of CP-Ti modified with micro arc oxidation and hydrothermal treatment showed that it can be a good potential candidate for biomedical applications instead of bare CP-Ti. Originality/value: Different HT conditions parameters and the hydroxyapatite crystallization mechanism on oxidized surfaces of the Cp-Ti samples was examined.