SATENDRA KUMAR - Academia.edu (original) (raw)
Papers by SATENDRA KUMAR
Environmental Progress & Sustainable Energy, 2012
The long-term stability of the slag in sea water is an essential requirement for its use in marin... more The long-term stability of the slag in sea water is an essential requirement for its use in marine environment. Because no specific standards exist for studying the leachability of slag in sea water, its longterm stability was assessed through four types of indigenously designed extraction tests: (i) extraction tests on the slag similar to that specified in the multiple extraction procedure USEPA 1320, however, using sea water as the leachant; (ii) mechanical activation of the slag followed by extraction test using sea water as leachant; (iii) pressure leaching of the slag (at 1000 psi) in N 2 and O 2 for 4 h at different temperatures up to 1208C; and (iv) mechanical activation of slag followed by pressure leaching of the slag in the temperature range of 40-1208C. In all these four tests, the leachability of the copper smelter slag was found to be higher in sea water compared to that in the Toxicity Characteristic Leaching Procedure medium and in acids. However, the highest concentration of all the relevant elements in the leachate was below the prescribed limits in USEPA method 1311.
Transactions of the Indian Institute of Metals, 2011
Stainless steels are widely used as orthopedic implant materials. The main problems with these im... more Stainless steels are widely used as orthopedic implant materials. The main problems with these implant materials are fatigue fracture, fretting fatigue, wear and corrosion. Surface mechanical attrition treatment (SMAT) is a newly developed method to improve the materials properties and performance. In the present study, AISI 304 SS was subjected to SMAT using 2, 5 and 8 mm [ 316L SS balls for 15, 30, 45 and 60 min at 50 Hz under vacuum. SMAT of 304 SS increased the surface roughness, induced the formation of mechanical twins, strain induced martensite phase, and increased the defect density, which is a function of the size of the balls and treatment time. SMAT using 5 and 8 mm [ balls significantly decreased the corrosion resistance whereas treatment using 2 mm [ balls enabled an anodic shift in E corr and a marginal decrease in i corr . However, increase in surface roughness leads to the formation of a defective passive film and a decrease in breakdown potential.
Wear, 2010
Fretting corrosion is a complex phenomena and a variety of factors such as load, contact area, fr... more Fretting corrosion is a complex phenomena and a variety of factors such as load, contact area, frequency, number of fretting cycles, extent of damage of the fretted zone, trapping of debris between the contacting surfaces, corrosivity of the medium, etc., will determine the fretting-corrosion behaviour. The present paper aims to develop a fretting-corrosion map of commercially pure Ti (CP-Ti) based on its frettingcorrosion behaviour in Ringer's solution under various combinations of load, frequency and number of fretting cycles. Based on the fretting-corrosion behaviour and restoration ability, a fretting-corrosion map of CP-Ti in Ringer's solution is developed for the first time. The fretting-corrosion map of CP-Ti in Ringer's solution enables identification of various regimes depending on the nature of predominant phenomenon for a given set of conditions. Since fretting corrosion is the dominant phenomenon at lesser duration of fretting at 5 and 10 Hz for a load of 3 and 5 N, the safer use of CP-Ti, particularly for hip and knee implants, is a major concern.
Wear, 2011
The present communication addresses the fretting corrosion behaviour of Ti-6Al-4V alloy in artifi... more The present communication addresses the fretting corrosion behaviour of Ti-6Al-4V alloy in artificial saliva containing 0, 190, 570 and 1140 ppm of fluoride ions. The fretting corrosion behaviour of Ti-6Al-4V alloy was evaluated based on the change in free corrosion potential (FCP) measured as a function of time. The wear morphology and surface profile of the fretted zone, assessed by scanning electron microscopy and non-contact optical profilometer, were used to ascertain the wear mechanism. The cathodic shift in FCP observed with the onset of fretting indicates damage of the passive film. After the fretting motion is ceased, an instantaneous repassivation of Ti-6Al-4V alloy is observed only in artificial saliva. The negative influence of fluoride ions on passive film formation hinders instantaneous repassivation of the damaged areas of the fretted zone. The morphology of the fretted zone reveals the occurrence of adhesive galling in all the cases. The wear volume of the fretted zone of Ti-6Al-4V alloy in artificial saliva free of fluoride ions is 3.26 × 10 12 nm 3 . In presence of 190 ppm of fluoride ions in artificial saliva, the wear volume is increased from 3.26 to 9.87 × 10 12 nm 3 . However, the wear volume is reduced to 6.95 × 10 12 nm 3 and 3.60 × 10 11 nm 3 at 570 and 1140 ppm of fluoride ions, respectively. The change in contact configuration from alumina-titanium to titanium-coated alumina-titanium reduced the mutual solubility between alumina and titanium, the extent of trapping and grinding of the wear debris and the wear rate of Ti-6Al-4V alloy in artificial saliva containing 1140 ppm of fluoride ions. The study reveals that the fretting corrosion behaviour of Ti-6Al-4V alloy in artificial saliva shows a strong dependence on the fluoride ion concentration.
Materials Science and Engineering: C, 2010
Fretting corrosion is one of the important reasons for the failure of prosthesis made of titanium... more Fretting corrosion is one of the important reasons for the failure of prosthesis made of titanium and titanium alloys under in vivo condition. The fretting-corrosion behaviour of untreated, anodized and thermally oxidized commercially pure titanium (CP-Ti) in Ringer's solution was evaluated based on the change in free corrosion potential (FCP) measured as a function of time. A comparison of the performance of untreated, anodized and thermally oxidized CP-Ti under fretting-corrosion conditions is reported for the first time in this paper. The study reveals that surface modification of CP-Ti by both anodizing and thermal oxidation improved the fretting-corrosion resistance of CP-Ti and among them the performance of thermally oxidized CP-Ti is superior to that of the anodized one. Adhesive galling is the predominant wear mechanism for untreated CP-Ti, adhesive wear and delamination are found to be operative for anodized CP-Ti whereas an abrasive wear mechanism is operative for thermally oxidized CP-Ti when they are fretted against an alumina ball.
Materials Science and Engineering: C, 2009
Commercially pure titanium (CP-Ti) samples were subjected to thermal oxidation (TO) treatment at ... more Commercially pure titanium (CP-Ti) samples were subjected to thermal oxidation (TO) treatment at 650°C for 8, 16, 24 and 48 h. The morphological features, structural characteristics, microhardness and corrosion resistance in Ringer's solution of thermally oxidized samples were compared with that of the untreated one, to ascertain the suitability of thermally oxidized sample as a bio-implant. The thickness, morphological features and phase constituents of the oxide film formed during thermal oxidation (TO) exhibit a strong dependence on the treatment time. Samples oxidized for 48 h lead to the formation of oxide grains along with a thick oxide film consisting of rutile and TiO phase. Samples oxidized for 24 h lead to the formation of oxide grains with thinner oxide layer at the grain boundary. Almost a 3 fold increase in hardness is observed for samples oxidized for 48 h compared to that of the untreated sample. Based on the corrosion protective ability, the untreated and thermally oxidized samples can be ranked as follows: {TO 48 h} N {TO 16 h} N {TO 8 h} ≈ {TO 24 h} N untreated. From corrosion protection point of view, TO for 48 h is a promising surface treatment and it can be a suitable alternative to the untreated CP-Ti as a bio-implant.
Materials Science and Engineering: C, 2010
... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman... more ... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman, Ganesh (2010) Corrigendum to Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment time [Mater. Sci. ...
Materials Chemistry and Physics, 2007
The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral... more The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral (pH 6.5) and acidified (pH 3.0) 3.5% NaCl solution was studied. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), currenttime transient, and ...
Materials Chemistry and Physics, 2010
Thermal oxidation (TO) of Ti6Al4V alloy was performed at 500, 650 and 800 • C for 8, 16, 24 and 4... more Thermal oxidation (TO) of Ti6Al4V alloy was performed at 500, 650 and 800 • C for 8, 16, 24 and 48 h in air. The morphological features, structural characteristics, microhardness and corrosion resistance in Ringer's solution of TO Ti6Al4V alloy were evaluated and compared with those of the untreated one. The surface morphological features reveal that the oxide film formed on Ti6Al4V alloy is adherent to the substrate at 500 and 650 • C irrespective of the oxidation time whereas it spalls off when the alloy is oxidized at 800 • C for more than 8 h. X-ray diffraction (XRD) measurement reveals the presence of Ti(O) and ␣-Ti phases on alloy oxidized at 500 and 650 • C, with Ti(O) as the dominant phase at 650 • C whereas the alloy oxidized at 800 • C exhibits only the rutile phase. Almost a threefold increase in hardness is observed for the alloy oxidized at 650 • C for 48 h when compared to that of the untreated one. Thermally oxidized Ti6Al4V alloy offers excellent corrosion resistance in Ringer's solution when compared to that of the untreated alloy.
Materials and Corrosion, 2011
The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric aci... more The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric acid was evaluated. The Ti-Mo alloys offered a better corrosion resistance than commercially pure titanium (CP-Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti-Mo alloys. The study recommends the use of Ti-Mo alloys, particularly Ti-25Mo alloy, as a suitable material of construction for sulphuric acid medium.
Journal of Materials Engineering and Performance, 2011
The characteristics of Ti6Al4V alloy subjected to thermal oxidation in air atmosphere at 650 8C f... more The characteristics of Ti6Al4V alloy subjected to thermal oxidation in air atmosphere at 650 8C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO 3 medium are addressed. When compared to the naturally formed oxide layer ($4-6 nm), a relatively thicker oxide scale ($7 mm) is formed throughout the surface of Ti6Al4V alloy after thermal oxidation. XRD pattern disclose the formation of the rutile and oxygen-diffused titanium as the predominant phases. A significant improvement in the hardness (from 324 AE 8 to 985 AE 40 HV 0.25 ) is observed due to the formation of hard oxide layer on the surface followed by the presence of an oxygen diffusion zone beneath it. Electrochemical studies reveal that the thermally oxidized Ti6Al4V alloy offers a better corrosion resistance than its untreated counterpart in both HCl and HNO 3 medium. The uniform surface coverage, compactness and thickness of the oxide layer provide an effective barrier towards corrosion of the Ti6Al4V alloy. The study concludes that thermal oxidation is an effective approach to engineer the surface of Ti6Al4V alloy to increase its corrosion resistance in HCl and HNO 3 medium.
Journal of Dentistry, 2008
j o u r n a l o f d e n t i s t r y 3 6 ( 2 0 0 8 ) 5 0 0 -5 0 7
Journal of Coatings Technology and Research, 2012
The problem of increasing the quality of older people life witch suffers of bones and dental dise... more The problem of increasing the quality of older people life witch suffers of bones and dental disease has led to important research for the development of biocompatible materials with high resistance to the action of biological factors and to the mechanical stress. The present study has like object to obtaining hydroxyapatite coatings on stainless steel using electrochemical method. By varying the deposition conditions were obtained layers with different coverage and morphologies. The hydroxyapatite deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The method used does not require large investments and by optimizing the parameters may be obtained deposition that present interest for the biocompatibility study.
Journal of Applied Electrochemistry, 2011
The corrosion behaviour of Ti-25Mo alloy in 0.9 wt% NaCl was evaluated by potentiodynamic polariz... more The corrosion behaviour of Ti-25Mo alloy in 0.9 wt% NaCl was evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and compared with that of commercially pure titanium (CP-Ti). The corrosion behaviour of Ti-25Mo alloy has been reported for the first time in this paper. The microstructure and structural characteristics were also examined using optical microscopy and X-ray diffraction (XRD), respectively. The study reveals that Ti-25Mo alloy possesses a b-phase microstructure. The Ti-25Mo alloy exhibits higher passivation range, lower average passive current density (i pass ) and higher charge transfer resistance (R ct ) compared to that of CP-Ti. Based on the corrosion protection ability, Ti-25Mo alloy can be a suitable alternative material for orthopaedic implant applications.
Journal of Alloys and Compounds, 2009
The corrosion behaviour of Ti-15Mo alloy in Ringer's solution was evaluated by potentiodynamic po... more The corrosion behaviour of Ti-15Mo alloy in Ringer's solution was evaluated by potentiodynamic polarization, cyclic polarization and chronoamperometric/current-time transient (CTT) studies. The corrosion protective ability of Ti-15Mo alloy was compared with that of commercially pure (CP) titanium (grade-2) and Ti-6Al-4V alloy under similar experimental conditions. The microstructure, microhardness and structural characteristics were also evaluated to ascertain the suitability of these materials for orthopaedic implant applications. The study reveals that Ti-15Mo alloy possesses a -phase microstructure and moderate hardness. The open circuit potential of Ti-15Mo alloy is relatively nobler than CP-Ti and Ti-6Al-4V alloy. The average passive current density of all the three Ti materials studied lies in the range of 32 × 10 −6 A/cm 2 . The passivation range of Ti-15Mo alloy is relatively large when compared to that of Ti-6Al-4V alloy and CP-Ti. The loop area of the cyclic polarization curve of Ti-15Mo alloy is quite similar to that of Ti-6Al-4V alloy but relatively smaller than that of CP-Ti. There is no appreciable variation in the steady state current density of all the three Ti materials measured at +0.5 V vs. SCE whereas a significant variation is observed at +1.25 V vs. SCE. Based on the -phase structure, moderate hardness and the ability to offer a better corrosion resistance in Ringer's solution, Ti-15Mo alloy can be used as a suitable alternative material for orthopaedic implant applications.
Corrosion Science, 2011
Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy imm... more Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy immersed in Ringer's solution for 92 h by electrochemical impedance spectroscopy (EIS) is addressed. The formation of a compact layer of well-developed rod-like aragonitic CaCO 3 crystals and its subsequent thickening with increase in immersion time offers a higher corrosion protective ability for ZM21 Mg alloy. The formation of a mud-crack pattern and a large number of clusters of needle-like crystals offers a relatively lower corrosion resistance for CP-Mg. The study suggests that ZM21 Mg alloy is a promising candidate material for the development of degradable implants.
Corrosion Science, 2010
The corrosion behaviour of Ti-15Mo alloy in 0.15 M NaCl containing 0.01, 0.03, 0.06 and 0.5 M NaF... more The corrosion behaviour of Ti-15Mo alloy in 0.15 M NaCl containing 0.01, 0.03, 0.06 and 0.5 M NaF is evaluated and its protective ability is compared with that of CP-Ti and Ti-6Al-4V alloy, to ascertain their suitability for dental implant application. The steady state current density of CP-Ti and, Ti-15Mo and Ti-6Al-4V alloys in 0.15 M NaCl containing 0.03 M NaF at 200 mV vs. SCE is found to be 1, 2 and 6 lA/cm 2 , respectively, which indicate that all of them could offer a better corrosion resistance in the potential range that could exists in the oral environment.
Corrosion Science, 2010
The influence of surface mechanical attrition treatment (SMAT) on the corrosion behaviour of AISI... more The influence of surface mechanical attrition treatment (SMAT) on the corrosion behaviour of AISI 409 grade stainless steel in 0.6 M NaCl was studied. SMAT using 2 mm £ 316L stainless steel (SS) balls for 15, 30 and 45 min and 5 mm £ balls for 15 min offers a better corrosion protective ability. In contrast, treatment using 5 mm £ balls for 30 and 45 min and by using 8 mm £ balls for 15, 30 and 45 min, induces microstrain and defect density that results in a decrease in corrosion resistance.
Corrosion Science, 2010
The fretting corrosion behaviour of thermally oxidized (at 650°C for 48 h) commercially pure (CP)... more The fretting corrosion behaviour of thermally oxidized (at 650°C for 48 h) commercially pure (CP) titanium in Ringer's solution was evaluated and reported for the first time in this paper. A cathodic shift in free corrosion potential (FCP) with the onset of fretting occurs very rapidly for untreated CP-Ti whereas it occurs over the entire 18,000 cycles for thermally oxidized (TO) CP-Ti and the extent of cathodic shift in FCP is relatively less for TO CP-Ti. The tribocorrosion performance of TO CP-Ti is better than that of untreated CP-Ti.
Environmental Chemistry Letters, Jun 1, 2011
The possibility of utilizing hydrochloric acidbased waste pickle liquor (WPL) and medium-grade py... more The possibility of utilizing hydrochloric acidbased waste pickle liquor (WPL) and medium-grade pyrolusite ore to synthesize manganese zinc ferrite was explored. The excess acidity of the WPL was neutralized using mild steel turnings. The unreacted mild steel scrap and suspended solids were removed by filtration. Partial precipitation technique was employed to reduce the impurities. The purified WPL was treated with mediumgrade pyrolusite ore to prepare the leach liquor to which the required quantities of ferrous chloride and zinc granules were added to maintain stoichiometry in the resultant compound. The hydroxy carbonate of manganese, zinc and iron was precipitated by the addition of a hot solution (70°C) of sodium carbonate (20% v/v), which upon sintering in argon atmosphere yielded manganese zinc ferrite. The addition of sodium lauryl sulfate (SLS) helped in preventing agglomeration of the particles. Sintering at 450°C for 30 min in argon atmosphere has resulted in mixed phases of (Zn,Mn,Fe) (Fe,Mn) 2 O 4 and Mn 3 O 4 , which indicates lack of phase purity. Sintering at temperatures higher than 950°C for 5 h in argon atmosphere enabled complete ferritization. The extent of ferritization was found to be a function of sintering time at 950°C. The manganese zinc ferrites synthesized using WPL and medium-grade pyrolusite ore exhibited soft magnetic characteristics.
Environmental Progress & Sustainable Energy, 2012
The long-term stability of the slag in sea water is an essential requirement for its use in marin... more The long-term stability of the slag in sea water is an essential requirement for its use in marine environment. Because no specific standards exist for studying the leachability of slag in sea water, its longterm stability was assessed through four types of indigenously designed extraction tests: (i) extraction tests on the slag similar to that specified in the multiple extraction procedure USEPA 1320, however, using sea water as the leachant; (ii) mechanical activation of the slag followed by extraction test using sea water as leachant; (iii) pressure leaching of the slag (at 1000 psi) in N 2 and O 2 for 4 h at different temperatures up to 1208C; and (iv) mechanical activation of slag followed by pressure leaching of the slag in the temperature range of 40-1208C. In all these four tests, the leachability of the copper smelter slag was found to be higher in sea water compared to that in the Toxicity Characteristic Leaching Procedure medium and in acids. However, the highest concentration of all the relevant elements in the leachate was below the prescribed limits in USEPA method 1311.
Transactions of the Indian Institute of Metals, 2011
Stainless steels are widely used as orthopedic implant materials. The main problems with these im... more Stainless steels are widely used as orthopedic implant materials. The main problems with these implant materials are fatigue fracture, fretting fatigue, wear and corrosion. Surface mechanical attrition treatment (SMAT) is a newly developed method to improve the materials properties and performance. In the present study, AISI 304 SS was subjected to SMAT using 2, 5 and 8 mm [ 316L SS balls for 15, 30, 45 and 60 min at 50 Hz under vacuum. SMAT of 304 SS increased the surface roughness, induced the formation of mechanical twins, strain induced martensite phase, and increased the defect density, which is a function of the size of the balls and treatment time. SMAT using 5 and 8 mm [ balls significantly decreased the corrosion resistance whereas treatment using 2 mm [ balls enabled an anodic shift in E corr and a marginal decrease in i corr . However, increase in surface roughness leads to the formation of a defective passive film and a decrease in breakdown potential.
Wear, 2010
Fretting corrosion is a complex phenomena and a variety of factors such as load, contact area, fr... more Fretting corrosion is a complex phenomena and a variety of factors such as load, contact area, frequency, number of fretting cycles, extent of damage of the fretted zone, trapping of debris between the contacting surfaces, corrosivity of the medium, etc., will determine the fretting-corrosion behaviour. The present paper aims to develop a fretting-corrosion map of commercially pure Ti (CP-Ti) based on its frettingcorrosion behaviour in Ringer's solution under various combinations of load, frequency and number of fretting cycles. Based on the fretting-corrosion behaviour and restoration ability, a fretting-corrosion map of CP-Ti in Ringer's solution is developed for the first time. The fretting-corrosion map of CP-Ti in Ringer's solution enables identification of various regimes depending on the nature of predominant phenomenon for a given set of conditions. Since fretting corrosion is the dominant phenomenon at lesser duration of fretting at 5 and 10 Hz for a load of 3 and 5 N, the safer use of CP-Ti, particularly for hip and knee implants, is a major concern.
Wear, 2011
The present communication addresses the fretting corrosion behaviour of Ti-6Al-4V alloy in artifi... more The present communication addresses the fretting corrosion behaviour of Ti-6Al-4V alloy in artificial saliva containing 0, 190, 570 and 1140 ppm of fluoride ions. The fretting corrosion behaviour of Ti-6Al-4V alloy was evaluated based on the change in free corrosion potential (FCP) measured as a function of time. The wear morphology and surface profile of the fretted zone, assessed by scanning electron microscopy and non-contact optical profilometer, were used to ascertain the wear mechanism. The cathodic shift in FCP observed with the onset of fretting indicates damage of the passive film. After the fretting motion is ceased, an instantaneous repassivation of Ti-6Al-4V alloy is observed only in artificial saliva. The negative influence of fluoride ions on passive film formation hinders instantaneous repassivation of the damaged areas of the fretted zone. The morphology of the fretted zone reveals the occurrence of adhesive galling in all the cases. The wear volume of the fretted zone of Ti-6Al-4V alloy in artificial saliva free of fluoride ions is 3.26 × 10 12 nm 3 . In presence of 190 ppm of fluoride ions in artificial saliva, the wear volume is increased from 3.26 to 9.87 × 10 12 nm 3 . However, the wear volume is reduced to 6.95 × 10 12 nm 3 and 3.60 × 10 11 nm 3 at 570 and 1140 ppm of fluoride ions, respectively. The change in contact configuration from alumina-titanium to titanium-coated alumina-titanium reduced the mutual solubility between alumina and titanium, the extent of trapping and grinding of the wear debris and the wear rate of Ti-6Al-4V alloy in artificial saliva containing 1140 ppm of fluoride ions. The study reveals that the fretting corrosion behaviour of Ti-6Al-4V alloy in artificial saliva shows a strong dependence on the fluoride ion concentration.
Materials Science and Engineering: C, 2010
Fretting corrosion is one of the important reasons for the failure of prosthesis made of titanium... more Fretting corrosion is one of the important reasons for the failure of prosthesis made of titanium and titanium alloys under in vivo condition. The fretting-corrosion behaviour of untreated, anodized and thermally oxidized commercially pure titanium (CP-Ti) in Ringer's solution was evaluated based on the change in free corrosion potential (FCP) measured as a function of time. A comparison of the performance of untreated, anodized and thermally oxidized CP-Ti under fretting-corrosion conditions is reported for the first time in this paper. The study reveals that surface modification of CP-Ti by both anodizing and thermal oxidation improved the fretting-corrosion resistance of CP-Ti and among them the performance of thermally oxidized CP-Ti is superior to that of the anodized one. Adhesive galling is the predominant wear mechanism for untreated CP-Ti, adhesive wear and delamination are found to be operative for anodized CP-Ti whereas an abrasive wear mechanism is operative for thermally oxidized CP-Ti when they are fretted against an alumina ball.
Materials Science and Engineering: C, 2009
Commercially pure titanium (CP-Ti) samples were subjected to thermal oxidation (TO) treatment at ... more Commercially pure titanium (CP-Ti) samples were subjected to thermal oxidation (TO) treatment at 650°C for 8, 16, 24 and 48 h. The morphological features, structural characteristics, microhardness and corrosion resistance in Ringer's solution of thermally oxidized samples were compared with that of the untreated one, to ascertain the suitability of thermally oxidized sample as a bio-implant. The thickness, morphological features and phase constituents of the oxide film formed during thermal oxidation (TO) exhibit a strong dependence on the treatment time. Samples oxidized for 48 h lead to the formation of oxide grains along with a thick oxide film consisting of rutile and TiO phase. Samples oxidized for 24 h lead to the formation of oxide grains with thinner oxide layer at the grain boundary. Almost a 3 fold increase in hardness is observed for samples oxidized for 48 h compared to that of the untreated sample. Based on the corrosion protective ability, the untreated and thermally oxidized samples can be ranked as follows: {TO 48 h} N {TO 16 h} N {TO 8 h} ≈ {TO 24 h} N untreated. From corrosion protection point of view, TO for 48 h is a promising surface treatment and it can be a suitable alternative to the untreated CP-Ti as a bio-implant.
Materials Science and Engineering: C, 2010
... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman... more ... Sci. Eng., 29 (2009) 19421949]. Satendra, Kumar and Sankara Narayanan, TSN and Sundara Raman, Ganesh (2010) Corrigendum to Thermal oxidation of CP-Ti: Evaluation of characteristics and corrosion resistance as a function of treatment time [Mater. Sci. ...
Materials Chemistry and Physics, 2007
The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral... more The corrosion behaviour of leaded brasses with 2, 2.4, 2.8, and 4.85 wt.% of lead in both neutral (pH 6.5) and acidified (pH 3.0) 3.5% NaCl solution was studied. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), currenttime transient, and ...
Materials Chemistry and Physics, 2010
Thermal oxidation (TO) of Ti6Al4V alloy was performed at 500, 650 and 800 • C for 8, 16, 24 and 4... more Thermal oxidation (TO) of Ti6Al4V alloy was performed at 500, 650 and 800 • C for 8, 16, 24 and 48 h in air. The morphological features, structural characteristics, microhardness and corrosion resistance in Ringer's solution of TO Ti6Al4V alloy were evaluated and compared with those of the untreated one. The surface morphological features reveal that the oxide film formed on Ti6Al4V alloy is adherent to the substrate at 500 and 650 • C irrespective of the oxidation time whereas it spalls off when the alloy is oxidized at 800 • C for more than 8 h. X-ray diffraction (XRD) measurement reveals the presence of Ti(O) and ␣-Ti phases on alloy oxidized at 500 and 650 • C, with Ti(O) as the dominant phase at 650 • C whereas the alloy oxidized at 800 • C exhibits only the rutile phase. Almost a threefold increase in hardness is observed for the alloy oxidized at 650 • C for 48 h when compared to that of the untreated one. Thermally oxidized Ti6Al4V alloy offers excellent corrosion resistance in Ringer's solution when compared to that of the untreated alloy.
Materials and Corrosion, 2011
The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric aci... more The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric acid was evaluated. The Ti-Mo alloys offered a better corrosion resistance than commercially pure titanium (CP-Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti-Mo alloys. The study recommends the use of Ti-Mo alloys, particularly Ti-25Mo alloy, as a suitable material of construction for sulphuric acid medium.
Journal of Materials Engineering and Performance, 2011
The characteristics of Ti6Al4V alloy subjected to thermal oxidation in air atmosphere at 650 8C f... more The characteristics of Ti6Al4V alloy subjected to thermal oxidation in air atmosphere at 650 8C for 48 h and its corrosion behavior in 0.1 and 4 M HCl and HNO 3 medium are addressed. When compared to the naturally formed oxide layer ($4-6 nm), a relatively thicker oxide scale ($7 mm) is formed throughout the surface of Ti6Al4V alloy after thermal oxidation. XRD pattern disclose the formation of the rutile and oxygen-diffused titanium as the predominant phases. A significant improvement in the hardness (from 324 AE 8 to 985 AE 40 HV 0.25 ) is observed due to the formation of hard oxide layer on the surface followed by the presence of an oxygen diffusion zone beneath it. Electrochemical studies reveal that the thermally oxidized Ti6Al4V alloy offers a better corrosion resistance than its untreated counterpart in both HCl and HNO 3 medium. The uniform surface coverage, compactness and thickness of the oxide layer provide an effective barrier towards corrosion of the Ti6Al4V alloy. The study concludes that thermal oxidation is an effective approach to engineer the surface of Ti6Al4V alloy to increase its corrosion resistance in HCl and HNO 3 medium.
Journal of Dentistry, 2008
j o u r n a l o f d e n t i s t r y 3 6 ( 2 0 0 8 ) 5 0 0 -5 0 7
Journal of Coatings Technology and Research, 2012
The problem of increasing the quality of older people life witch suffers of bones and dental dise... more The problem of increasing the quality of older people life witch suffers of bones and dental disease has led to important research for the development of biocompatible materials with high resistance to the action of biological factors and to the mechanical stress. The present study has like object to obtaining hydroxyapatite coatings on stainless steel using electrochemical method. By varying the deposition conditions were obtained layers with different coverage and morphologies. The hydroxyapatite deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). The method used does not require large investments and by optimizing the parameters may be obtained deposition that present interest for the biocompatibility study.
Journal of Applied Electrochemistry, 2011
The corrosion behaviour of Ti-25Mo alloy in 0.9 wt% NaCl was evaluated by potentiodynamic polariz... more The corrosion behaviour of Ti-25Mo alloy in 0.9 wt% NaCl was evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and compared with that of commercially pure titanium (CP-Ti). The corrosion behaviour of Ti-25Mo alloy has been reported for the first time in this paper. The microstructure and structural characteristics were also examined using optical microscopy and X-ray diffraction (XRD), respectively. The study reveals that Ti-25Mo alloy possesses a b-phase microstructure. The Ti-25Mo alloy exhibits higher passivation range, lower average passive current density (i pass ) and higher charge transfer resistance (R ct ) compared to that of CP-Ti. Based on the corrosion protection ability, Ti-25Mo alloy can be a suitable alternative material for orthopaedic implant applications.
Journal of Alloys and Compounds, 2009
The corrosion behaviour of Ti-15Mo alloy in Ringer's solution was evaluated by potentiodynamic po... more The corrosion behaviour of Ti-15Mo alloy in Ringer's solution was evaluated by potentiodynamic polarization, cyclic polarization and chronoamperometric/current-time transient (CTT) studies. The corrosion protective ability of Ti-15Mo alloy was compared with that of commercially pure (CP) titanium (grade-2) and Ti-6Al-4V alloy under similar experimental conditions. The microstructure, microhardness and structural characteristics were also evaluated to ascertain the suitability of these materials for orthopaedic implant applications. The study reveals that Ti-15Mo alloy possesses a -phase microstructure and moderate hardness. The open circuit potential of Ti-15Mo alloy is relatively nobler than CP-Ti and Ti-6Al-4V alloy. The average passive current density of all the three Ti materials studied lies in the range of 32 × 10 −6 A/cm 2 . The passivation range of Ti-15Mo alloy is relatively large when compared to that of Ti-6Al-4V alloy and CP-Ti. The loop area of the cyclic polarization curve of Ti-15Mo alloy is quite similar to that of Ti-6Al-4V alloy but relatively smaller than that of CP-Ti. There is no appreciable variation in the steady state current density of all the three Ti materials measured at +0.5 V vs. SCE whereas a significant variation is observed at +1.25 V vs. SCE. Based on the -phase structure, moderate hardness and the ability to offer a better corrosion resistance in Ringer's solution, Ti-15Mo alloy can be used as a suitable alternative material for orthopaedic implant applications.
Corrosion Science, 2011
Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy imm... more Evaluation of the corrosion behavior of commercially pure magnesium (CP-Mg) and ZM21 Mg alloy immersed in Ringer's solution for 92 h by electrochemical impedance spectroscopy (EIS) is addressed. The formation of a compact layer of well-developed rod-like aragonitic CaCO 3 crystals and its subsequent thickening with increase in immersion time offers a higher corrosion protective ability for ZM21 Mg alloy. The formation of a mud-crack pattern and a large number of clusters of needle-like crystals offers a relatively lower corrosion resistance for CP-Mg. The study suggests that ZM21 Mg alloy is a promising candidate material for the development of degradable implants.
Corrosion Science, 2010
The corrosion behaviour of Ti-15Mo alloy in 0.15 M NaCl containing 0.01, 0.03, 0.06 and 0.5 M NaF... more The corrosion behaviour of Ti-15Mo alloy in 0.15 M NaCl containing 0.01, 0.03, 0.06 and 0.5 M NaF is evaluated and its protective ability is compared with that of CP-Ti and Ti-6Al-4V alloy, to ascertain their suitability for dental implant application. The steady state current density of CP-Ti and, Ti-15Mo and Ti-6Al-4V alloys in 0.15 M NaCl containing 0.03 M NaF at 200 mV vs. SCE is found to be 1, 2 and 6 lA/cm 2 , respectively, which indicate that all of them could offer a better corrosion resistance in the potential range that could exists in the oral environment.
Corrosion Science, 2010
The influence of surface mechanical attrition treatment (SMAT) on the corrosion behaviour of AISI... more The influence of surface mechanical attrition treatment (SMAT) on the corrosion behaviour of AISI 409 grade stainless steel in 0.6 M NaCl was studied. SMAT using 2 mm £ 316L stainless steel (SS) balls for 15, 30 and 45 min and 5 mm £ balls for 15 min offers a better corrosion protective ability. In contrast, treatment using 5 mm £ balls for 30 and 45 min and by using 8 mm £ balls for 15, 30 and 45 min, induces microstrain and defect density that results in a decrease in corrosion resistance.
Corrosion Science, 2010
The fretting corrosion behaviour of thermally oxidized (at 650°C for 48 h) commercially pure (CP)... more The fretting corrosion behaviour of thermally oxidized (at 650°C for 48 h) commercially pure (CP) titanium in Ringer's solution was evaluated and reported for the first time in this paper. A cathodic shift in free corrosion potential (FCP) with the onset of fretting occurs very rapidly for untreated CP-Ti whereas it occurs over the entire 18,000 cycles for thermally oxidized (TO) CP-Ti and the extent of cathodic shift in FCP is relatively less for TO CP-Ti. The tribocorrosion performance of TO CP-Ti is better than that of untreated CP-Ti.
Environmental Chemistry Letters, Jun 1, 2011
The possibility of utilizing hydrochloric acidbased waste pickle liquor (WPL) and medium-grade py... more The possibility of utilizing hydrochloric acidbased waste pickle liquor (WPL) and medium-grade pyrolusite ore to synthesize manganese zinc ferrite was explored. The excess acidity of the WPL was neutralized using mild steel turnings. The unreacted mild steel scrap and suspended solids were removed by filtration. Partial precipitation technique was employed to reduce the impurities. The purified WPL was treated with mediumgrade pyrolusite ore to prepare the leach liquor to which the required quantities of ferrous chloride and zinc granules were added to maintain stoichiometry in the resultant compound. The hydroxy carbonate of manganese, zinc and iron was precipitated by the addition of a hot solution (70°C) of sodium carbonate (20% v/v), which upon sintering in argon atmosphere yielded manganese zinc ferrite. The addition of sodium lauryl sulfate (SLS) helped in preventing agglomeration of the particles. Sintering at 450°C for 30 min in argon atmosphere has resulted in mixed phases of (Zn,Mn,Fe) (Fe,Mn) 2 O 4 and Mn 3 O 4 , which indicates lack of phase purity. Sintering at temperatures higher than 950°C for 5 h in argon atmosphere enabled complete ferritization. The extent of ferritization was found to be a function of sintering time at 950°C. The manganese zinc ferrites synthesized using WPL and medium-grade pyrolusite ore exhibited soft magnetic characteristics.