Influence of the frequency on the structure and corrosion resistance of ceramic coatings on Ti–6Al–4V alloy produced by micro-plasma oxidation

2005 ◽  
Vol 92 (2-3) ◽  
pp. 408-412 ◽  
Author(s):  
Zhongping Yao ◽  
Zhaohua Jiang ◽  
Xuetong Sun ◽  
Shigang Xin ◽  
Zhendong Wu
Keyword(s):  
Corrosion Resistance ◽  
Ceramic Coatings ◽  
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 current density on structure and corrosion resistance of ceramic coatings on Ti–6Al–4V alloy by micro-plasma oxidation

2004 ◽  
Vol 468 (1-2) ◽  
pp. 120-124 ◽  
Author(s):  
Zhongping Yao ◽  
Zhaohua Jiang ◽  
Xuetong Sun ◽  
Shigang Xin ◽  
Yanping Li
Keyword(s):  
Corrosion Resistance ◽  
Current Density ◽  
Ceramic Coatings ◽  
Plasma Oxidation

Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings

2007 ◽  
Author(s):  
Lida Shen ◽  
Yinhui Huang ◽  
Zongjun Tian ◽  
Guoran Hua
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Bond Coat ◽  
Continuous Wave ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Al2o3 Ceramic ◽  
Plasma Sprayed ◽  
Steel Substrates

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.

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.

scholarly journals Corrosion Behavior and Surface Treatment of Cladding Materials Used in High-Temperature Lead-Bismuth Eutectic Alloy: A Review

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 364
Author(s):  
Hao Wang ◽  
Jun Xiao ◽  
Hui Wang ◽  
Yong Chen ◽  
Xing Yin ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Liquid Metal ◽  
Energy Demand ◽  
Ceramic Coatings ◽  
High Entropy Alloy ◽  
Pressurized Water ◽  
Corrosion Morphology ◽  
High Entropy ◽  
Lead Bismuth Eutectic

Liquid metal fast reactors were considered to be the most promising solution to meet the enormous energy demand in the future. However, corrosion phenomenon caused by the liquid metal, especially in high-temperature lead-bismuth coolant, has greatly hindered the commercialization of the advanced Generation-IV nuclear system. This review discussed current research on the corrosion resistance of structural materials (such as EP823, T91, ODS, and authentic steels) in high-temperature liquid metal served as reactor coolants. The current corrosion resistance evaluation has proved that even for the excellent performance of EP823, the structural material selected in pressurized water reactor is not the ideal material for operation in the high-temperature lead-bismuth eutectic (LBE). Furthermore, the latest coating technologies that are expected to be applied to cladding materials for coolant system were extensively discussed, including Al-containing coatings, ceramic coatings, oxide coatings, amorphous coatings and high-entropy alloy coatings. The detailed comparison summarized the corrosion morphology and corrosion products of various coatings in LBE. This review not only provided a systematic understanding of the corrosion phenomena, but also demonstrated that coating technology is an effective method to solve the corrosion issues of the advanced next-generation reactors.

Protective and Thermophysical Characteristics of Plasma-Electrolytic Coatings on the Ultra-Light Magnesium Alloy

2021 ◽  
pp. 1-15
Author(s):  
Sergey Grigoriev ◽  
Igor Kondratsky ◽  
Boris Krit ◽  
Valery Ludin ◽  
Varvara Medvetskova ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Thermal Diffusivity ◽  
Magnesium Alloys ◽  
Ceramic Coatings ◽  
Specific Electrical Conductivity ◽  
Technological Parameters ◽  
Thermophysical Characteristics ◽  
Light Alloy ◽  
Plasma Electrolytic ◽  
Integral Assessment

Abstract Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.

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