Structure and Adhesion of Hydroxyapatite Films Electrochemically Deposited onto Titanium Substrates under Short-Pulse Current in Metastable Calcium Phosphate Solution

2008 ◽  
Vol 396-398 ◽  
pp. 377-380 ◽  
Author(s):  
Kawashita Masakazu ◽  
Tomoyasu Hayakawa ◽  
Gikan H. Takaoka ◽  
Toshiki Miyazaki
Keyword(s):  
Calcium Phosphate ◽  
Adhesive Strength ◽  
Pulse Current ◽  
Lattice Mismatch ◽  
Short Pulse ◽  
Ion Concentration ◽  
Phosphate Solution ◽  
Average Current Density ◽  
Electrochemically Deposited ◽  
Average Current

Hydroxyapatite (HA) films were deposited onto titanium (Ti) metal substrates by an electrodeposition method under a short-pulse current. Metastable calcium phosphate solution was used as the electrolyte. The ion concentration of the solution was 1.5 times that of human body fluid, but the solution did not contain magnesium ions at 36.5°C. We used an average current density of 0.01 A/cm2 and current-on time (TON) equal to current-off time (TOFF) of 10 ms, 100 ms, 1 s, and 15 s. The adhesive strength between HA and Ti substrates were relatively high at TON = TOFF = 10 ms. It is considered that small calcium phosphate crystals with low crystallinity were deposited on the Ti surface without reacting with other calcium phosphate crystals, H2O, and HCO3– in the surrounding environment. This resulted in relaxation of the lattice mismatch and enhancement of the adhesive strength between the HA crystals and Ti substrates.

Effect of pulse current on structure and adhesion of apatite electrochemically deposited onto titanium substrates

2008 ◽  
Vol 23 (12) ◽  
pp. 3176-3183 ◽  
Author(s):  
Tomoyasu Hayakawa ◽  
Masakazu Kawashita ◽  
Gikan H. Takaoka ◽  
Toshiki Miyazaki
Keyword(s):  
Calcium Phosphate ◽  
Adhesive Strength ◽  
Pulse Current ◽  
Lattice Mismatch ◽  
Ion Concentration ◽  
Phosphate Solution ◽  
Average Current Density ◽  
Electrochemically Deposited ◽  
Average Current ◽  
Titanium Substrates

Apatite films were deposited onto titanium (Ti) metal substrates by an electrodeposition method under a pulse current. Metastable calcium phosphate solution was used as the electrolyte. The ion concentration of the solution was 1.5 times that of human body fluid, but the solution did not contain magnesium ions at 36.5 °C. We used an average current density of 0.01 A/cm2 and current-on time (TON) equal to current-off time (TOFF) of 10 ms, 100 ms, 1 s, and 15 s. The adhesive strength between apatite and Ti substrates were relatively high at TON = TOFF = 10 ms. It is considered that small calcium phosphate (C–P) crystals with low crystallinity were deposited on the Ti surface without reacting with other C–P crystals, H2O, and HCO3− in the surrounding environment. This resulted in relaxation of the lattice mismatch and enhancement of the adhesive strength between the apatite crystals and Ti substrates.

Electrochemical Deposition of Apatite on Titanium Substrates by Using Pulse Current

2007 ◽  
Vol 361-363 ◽  
pp. 629-632 ◽  
Author(s):  
Kawashita Masakazu ◽  
Tomoyasu Hayakawa ◽  
Gikan H. Takaoka
Keyword(s):  
Electrochemical Deposition ◽  
Deposition Time ◽  
Pulse Current ◽  
Apatite Layer ◽  
Phosphate Solution ◽  
Metallic Materials ◽  
Average Current Density ◽  
Average Current ◽  
Pre Treatment ◽  
Titanium Substrates

An apatite layer was successfully formed on titanium substrates by electrochemical deposition under a pulse current in a metastable calcium phosphate solution, which had 1.5 times the ion concentrations of a normal simulated body fluid, but did not contain MgCl2·6H2O, at 40 °C for 30, 60, 90 and 120 minutes at the average current density of 10 mA/cm2. The thickness of the apatite layer was increased with increasing deposition time. The pulse-current deposition produced the thicker apatite layer than the direct-current deposition, and gave some effects on the surface morphology of the apatite. The pre-treatment using acid solution gave a better adhesive between apatite and substrate. It is expected that the present electrochemical deposition under a pulse current will be useful to rapidly coat apatite on metallic materials.

scholarly journals Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 111
Author(s):  
Ivana O. Mladenović ◽  
Nebojša D. Nikolić ◽  
Jelena S. Lamovec ◽  
Dana Vasiljević-Radović ◽  
Vesna Radojević
Keyword(s):  
Mechanical Characteristics ◽  
Dislocation Creep ◽  
Average Current Density ◽  
Fine Grained ◽  
Copper Coatings ◽  
Electrochemically Deposited ◽  
Composite Models ◽  
Average Current ◽  
Composite Hardness ◽  
Coating Hardness

The mechanical characteristics of electrochemically deposited copper coatings have been examined by application of two hardness composite models: the Chicot-Lesage (C-L) and the Cheng-Gao (C-G) models. The 10, 20, 40 and 60 µm thick fine-grained Cu coatings were electrodeposited on the brass by the regime of pulsating current (PC) at an average current density of 50 mA cm−2, and were characterized by scanning electron (SEM), atomic force (AFM) and optical (OM) microscopes. By application of the C-L model we determined a limiting relative indentation depth (RID) value that separates the area of the coating hardness from that with a strong effect of the substrate on the measured composite hardness. The coating hardness values in the 0.9418–1.1399 GPa range, obtained by the C-G model, confirmed the assumption that the Cu coatings on the brass belongs to the “soft film on hard substrate” composite hardness system. The obtained stress exponents in the 4.35–7.69 range at an applied load of 0.49 N indicated that the dominant creep mechanism is the dislocation creep and the dislocation climb. The obtained mechanical characteristics were compared with those recently obtained on the Si(111) substrate, and the effects of substrate characteristics such as hardness and roughness on the mechanical characteristics of the electrodeposited Cu coatings were discussed and explained.

scholarly journals The study of Zn–Co alloy coatings electrochemically deposited by pulse current

2012 ◽  
Vol 66 (5) ◽  
pp. 749-757 ◽  
Author(s):  
Jelena Bajat ◽  
Miodrag Maksimovic ◽  
Milorad Tomic ◽  
Miomir Pavlovic
Keyword(s):  
Surface Roughness ◽  
Current Efficiency ◽  
Direct Current ◽  
Current Density ◽  
Pulse Current ◽  
Pulse Plating ◽  
Cathodic Current ◽  
Average Current Density ◽  
Corrosion Stability ◽  
Average Current

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2).

Preparation of Ni-ZrO2-CeO2 Nanocomposite Coatings by Pulse Electrodeposition

2013 ◽  
Vol 395-396 ◽  
pp. 174-178 ◽  
Author(s):  
Yang Yang Xu ◽  
Yu Jun Xue ◽  
Fang Yang ◽  
Chun Yang Liu ◽  
Ji Shun Li
Keyword(s):  
Current Density ◽  
Smooth Surface ◽  
Pulse Current ◽  
Nanocomposite Coating ◽  
Pulse Electrodeposition ◽  
Nanocomposite Coatings ◽  
Duty Ratio ◽  
Average Current Density ◽  
Average Current ◽  
Surface Morphologies

Ni-ZrO2-CeO2nanocomposite coatings were prepared by pulse electrodeposition. The effect additions of ZrO2and CeO2nanoparticles, average current density, duty ratio and frequency of pulse current on nanoparticle contents of Ni-ZrO2-CeO2nanocomposites were studied. The surface morphologies and microhardness of different nanocomposite coatings (Ni-ZrO2, Ni-CeO2, Ni-ZrO2-CeO2) were analyzed. The results show that, with the average current density, duty ratio and frequency increased, the nanoparticle contents increased at first and then decreased. Compared with Ni-ZrO2and Ni-CeO2, the surface morphology of Ni-ZrO2-CeO2nanocomposite coating showed better smooth surface and more compact microstructure, the microhardness was also higher.

Effect of Pulse Electrodeposition Parameters on Microhardness of Ni-ZrO2-CeO2 Nanocomposite Coating

2014 ◽  
Vol 1049-1050 ◽  
pp. 31-34
Author(s):  
Shuang Shuang Liu ◽  
Yu Jun Xue ◽  
Yang Yang Xu ◽  
Ji Shun Li
Keyword(s):  
Composite Coating ◽  
Current Density ◽  
Pulse Current ◽  
Pulse Frequency ◽  
Nanocomposite Coating ◽  
Pulse Electrodeposition ◽  
Duty Ratio ◽  
Positive Duty ◽  
Average Current Density ◽  
Average Current

Ni-ZrO2-CeO2 nanocomposite coating was prepared by pulse electrodeposition. The effect of addition of ZrO2 and CeO2 nanoparticles, average current density, duty cycle and pulse current on microhardness of Ni-ZrO2-CeO2 nanocomposites were studied. The results show that microhardness of nanocomposite is increased at first and then decreased with the increasing additive amounts of two kinds of nanoparticles. With increasing reverse the average current density, the microhardness of the composite coating increases. Also, the microhardness of nanocomposite fall with the increasing of pulse frequency. With the positive duty ratio increasing, the microhardness of the composite coating increase at first and then decreased, but with the increasing of the reverse duty ratio, the microhardness of nanocomposite coating is gradually decreased.

Influences of Pulse Current Density on the Characteristics of Ni-W-P-CeO2-SiO2 Composite Coatings

2011 ◽  
Vol 418-420 ◽  
pp. 856-860 ◽  
Author(s):  
Rui Dong Xu ◽  
Da Cheng Zhai ◽  
Shuang Li Hu
Keyword(s):  
Chemical Composition ◽  
Current Density ◽  
Pulse Current ◽  
Composite Coatings ◽  
Average Current Density ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Average Current ◽  
S Deposition ◽  
Microhardness Tester

Square-wave double pulse current was used to electrodeposit Ni-W-P-CeO2-SiO2composite coatings in fine-grained structure on the surface of carbon steel, influences of forward pulse average current density, +Jm, in the range of 5~25A/dm2on characteristics of the composite coatings were researched, and the chemical compositionSubscript texts, deposition rate, microhardness and microstructures were evaluated by EDX, SEM and Microhardness tester. The results show that the uniform composite coatings can be obtained at +Jmof 20A/dm2, which possess higher microhardness of 735Hv. The grains sizes of the composite coatings decrease when +Jmis increased from 5A/dm2to 20A/dm2, while the reappearance of large grains structure at 25A/dm2.

Technology on Ni-ZrO2-CeO2 Nanocomposites by Pulse Electroforming in an Ultrasonic Field

2013 ◽  
Vol 579-580 ◽  
pp. 138-143
Author(s):  
Yang Yang Xu ◽  
Yu Jun Xue ◽  
Ji Shun Li ◽  
Yi Liu ◽  
Fang Yang
Keyword(s):  
Surface Morphology ◽  
Current Density ◽  
Pulse Current ◽  
Ultrasonic Field ◽  
Double Pulse ◽  
Duty Ratio ◽  
Positive Duty ◽  
Average Current Density ◽  
Average Current ◽  
Positive Frequency

Ni-ZrO2-CeO2 nanocomposites were prepared by double-pulse current in an ultrasonic field. The effect of average current density, duty ratio and frequency of double-pulse current on nanoparticles content of Ni-ZrO2-CeO2 nanocomposites was studied. Meanwhile, surface morphology and microhardness of nanocomposites were analyzed. The results show that, with the positive average current density, positive duty ratio and positive frequency increased, the nanoparticles contents increased at first and then decreased. On the contrary, it reduced while reverse average current density, reverse duty ratio and reverse frequency were increasing. Compared with Ni-ZrO2-CeO2 prepared by direct current and monopulse current, grain of Ni-ZrO2-CeO2 nanocomposite prepared by double-pulse current is finer, the microhardness is also higher.

Effect of Frequency on Composition and Microstructure of Siliconized Layer Using Pulse Electrodeposition

2011 ◽  
Vol 189-193 ◽  
pp. 1113-1116 ◽  
Author(s):  
Hai Li Yang ◽  
Ping Ju Hao ◽  
Guo Zhang Tang ◽  
Yun Gang Li
Keyword(s):  
Pulse Current ◽  
Steel Substrate ◽  
Pulse Frequency ◽  
Grain Structure ◽  
Experimental Conditions ◽  
Average Current Density ◽  
High Frequencies ◽  
Fine Grain ◽  
Average Current ◽  
Si Content

The siliconized layer on low silicon steel substrate was produced under pulse current conditions from KCl-NaCl-NaF-SiO2molten salt and the effects of frequency on the composition and microstructure were investigated. The results showed that at the same average current density and other experimental conditions, Si content in the surface and the layer thickness decreased with increasing frequency. Low pulse frequency (500 Hz) and high frequencies (1500, 2000Hz) produced coarse grain and bigger surface roughness. There was a flat fine grain structure and a relatively thick (30m) layer when the frequency was 1000Hz. However, the effect of pulse frequency on the structure of the layer was not obvious. The phase structure of the layer was composed of Fe3Si with (110) preferred orientation at all experimental frequencies.

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