Effects of duty ratio at high frequency on growth mechanism of micro-plasma oxidation ceramic coatings on Ti alloy

2007 ◽  
Vol 42 (22) ◽  
pp. 9434-9439 ◽  
Author(s):  
Zhongping Yao ◽  
Yanli Jiang ◽  
Zhaohua Jiang ◽  
Fuping Wang
Keyword(s):  
Growth Mechanism ◽  
High Frequency ◽  
Ceramic Coatings ◽  
Duty Ratio ◽  
Ti Alloy ◽  
Plasma Oxidation

Effects of duty ratio at low frequency on growth mechanism of micro-plasma oxidation ceramic coatings on Ti alloy

2007 ◽  
Vol 253 (16) ◽  
pp. 6778-6783 ◽  
Author(s):  
Zhongping Yao ◽  
Ruihai Cui ◽  
Zhaohua Jiang ◽  
Fuping Wang
Keyword(s):  
Growth Mechanism ◽  
Low Frequency ◽  
Ceramic Coatings ◽  
Duty Ratio ◽  
Ti Alloy ◽  
Plasma Oxidation

Influences of Duty Ratio on Structure and Corrosion Resistance of Ceramic Coatings on Ti-6Al-4V by Micro-Plasma Oxidation

2007 ◽  
Vol 336-338 ◽  
pp. 2454-2457
Author(s):  
Hong Qi Ben ◽  
Zhong Ping Yao ◽  
Zhao Hua Jiang
Keyword(s):  
Corrosion Resistance ◽  
Outer Layer ◽  
Oxidation Process ◽  
Ceramic Coatings ◽  
Duty Ratio ◽  
Plasma Oxidation ◽  
Rutile Tio2 ◽  
Key Factor ◽  
Α Al2o3 ◽  
Better Than

Duty ratio is a key factor during micro-plasma oxidation process. Its influences on structure and corrosion resistance of ceramic coatings on Ti–6Al–4V by pulsed bi-polar MPO in NaAlO2 solution were investigated. The ceramic coatings were composed of Al2TiO5, α-Al2O3 and rutile TiO2, of which Al2TiO5 was the main crystalline. The coating can be divided into a porous outer layer and a dense inner layer. Compared with the condition of the same duty ratio for both pulses, the rise of anode duty ratio (D1) led to an increase in the amount of Al2TiO5 and α-Al2O3 and increased the thickness of the coating; whereas the rise of cathode duty ratio (D2) led to a decrease in the amount of α-Al2O3 and decreased the thickness of the coating. Besides, the corrosion resistance of the coated samples was better than that of Ti-6Al-4V substrate. When D1 / D2 = 60 / 30, the produced coating’s corrosion resistance was best.

Influences of Calcination Ambiences on Phase Composition and High Temperature Oxidation Resistance Property of Ceramic Coatings on Ti–6Al–4V Alloy by Micro-Plasma Oxidation

2007 ◽  
Vol 336-338 ◽  
pp. 2481-2483 ◽  
Author(s):  
Guo Dong Hao ◽  
Zhao Hua Jiang ◽  
Zhong Ping Yao ◽  
Heng Ze Xian ◽  
Yan Li Jiang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Ceramic Coatings ◽  
Plasma Oxidation ◽  
Temperature Oxidation ◽  
Complete Decomposition ◽  
Weight Gains ◽  
High Temperature Calcination

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared on Ti-6Al-4V alloy by pulsed bi-polar micro-plasma oxidation (MPO) in NaAlO2 solution. The coated samples were calcined in Ar and air at 1000oC, respectively. The phase composition, morphology and element content of the coatings were investigated by XRD, SEM and XRF. The samples treated in Ar and the as-coated ones were calcined in air at 1000oC to study the oxidation resistance of the samples. The results showed that Al2TiO5 decomposed and transformed into corundum and rutile TiO2 during the high temperature calcination. Al2TiO5 decomposed very quickly in air and the proportion of Al2O3 to TiO2 was 44:55 after a complete decomposition. On the contrary, Al2TiO5 decomposed very slowly in argon with the final proportion of Al2O3 to TiO2 of 81:18 on the coating surface. The morphology of the ceramic coatings after the calcination was also different. The coatings calcined in argon were fined: the grains and pores were smaller than those of the coatings calcined in air. The weight gains of both coatings changed in the form of parabola law, and the weight gains of the coated samples treated in argon were comparatively lower than that of the as-coated samples. During the high temperature calcination, the samples treated in argon cannot distort easily, compared with the as-coated ones.

Interface Biomechanical Properties between Femora and Bioactive Ceramic Coatings Prostheses during the Initial Implant Stage

2007 ◽  
Vol 336-338 ◽  
pp. 1806-1809
Author(s):  
Liu Ding Tang ◽  
W.M. Zhao ◽  
L.Y. Tian ◽  
Bing Zhe Li
Keyword(s):  
Circumferential Stress ◽  
Biomechanical Properties ◽  
Ceramic Coatings ◽  
Homogeneous Layer ◽  
Ti Alloy ◽  
Biomechanical Models ◽  
Press Fit ◽  
The Press ◽  
Shearing Strength ◽  
Bioactive Ceramic

Biomechanical models of implanting prostheses into femora by means of press fit, i.e. the mechanics of non-homogeneous layer-like composites, have been used to quantify the press-fit strength and circumferential stress of the interface, when femora are partially replaced by different thicknesses of bioactive ceramic coatings on a prosthesis surface during the initial implant stage. The maximum press-fit strength appears on the interface between femora and Ti alloy prostheses with non-coating; the press-fit strength decreases with the increased thickness of the coating. The circumferential stress displayed as the large tensile stress at the femoral side of the interface; the compressive stress, appeared at the side of the coating and Ti alloy prosthesis. The shearing strength, jointing between the prostheses and femora would be bigger with the thinner bioactive ceramic coatings. Considering the biodegradability of bioactive ceramic coatings, e.g. hydroxyapatite, HA, it is concluded that the optimum thickness of the bioactive ceramic coatings will be about 50-60 microns.

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