INFLUENCE OF ELECTROLYTIC PLASMA OXIDATION COATING ON TENSILE BEHAVIOR OF DIE-CAST AM50 ALLOY SUBJECTED TO SALT CORROSION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 960-965 ◽  
Author(s):  
LIHONG HAN ◽  
XUEYUAN NIE ◽  
PENG ZHANG ◽  
QIANG ZHANG ◽  
HENRY HU
Keyword(s):  
Mixed Layer ◽  
Ceramic Coatings ◽  
Ductile Deformation ◽  
Plasma Oxidation ◽  
Micro Cracks ◽  
Immersion Corrosion ◽  
Die Cast ◽  
Am50 Alloy ◽  
Electrolytic Plasma Oxidation ◽  
Fractured Surface

Three different thickness ceramic coatings were deposited on die-cast AM50 magnesium alloy in KOH and NaAlO 2 solution using electrolytic plasma oxidation (EPO) technology for corrosion prevention. Immersion corrosion tests were carried out in 3.5% NaCl solution for 336 hours to investigate the effect of coating thicknesses on tensile and fracture behaviors of the coated AM50 alloys. The results show that the yield strength (YS) and ultimate tensile strength (UTS) of the coated AM50 alloy subjected to immersion corrosion increase with an increase in coating thicknesses. Further analyses on stress and strain curves indicate that the coating enhances the strain-hardening rates of the corroded alloy during its plastic deformation. SEM examination on the fractured surface manifests that the substrate AM50 alloys exhibit characteristics of ductile deformation with deep dimples. However, brittle features prevail on the fractured surface of the mixed layer of coating plus oxidation corrosion product. Micro cracks were observed between the mixed layer and the AM50 alloy substrate induced by corrosion and within the mixed layer induced by EPO process, which could be responsible for the brittle fracture.

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.

Anti-Wear Coating Grown by Micro-Plasma Oxidation on Aluminum Alloys in the Solution of Aluminate-Titania

2011 ◽  
Vol 239-242 ◽  
pp. 667-670 ◽  
Author(s):  
Li Gong Zhang ◽  
Gui Mei Zhao ◽  
Xiao Ming Lai
Keyword(s):  
Aluminum Alloys ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Wear Property ◽  
Plasma Oxidation ◽  
X Ray Diffraction ◽  
Electrolytic Solution ◽  
X Ray ◽  
Hardness Tester ◽  
Wear Coating

In this paper, Aluminum trioxide ceramic coatings were grown on surfaces of 2024 Aluminum alloys by micro-plasma oxidation in an aluminate electrolytic solution. In order to decrease the density of the pores and increase the anti-wear property of the ceramic coatings, Titania were added into the aluminate electrolytic solution. The struture and anti-wear property of the produced ceramic coatings were measured by X-ray diffraction, scanning electron microscope , hardness tester and frictionometer. The results show that the thickness of the ceramic coating is about 24±1 μm, surfaces of the ceramic coatings are very uniform. The hardness of the doped coating is up to 930 HV, and the wear property of the coating is the more excellent than that of undoped coating.

Corrosion Properties of Plasma Oxidized Titanium Nitride for Biomedical Applications

2015 ◽  
Vol 227 ◽  
pp. 471-474 ◽  
Author(s):  
Jerzy Robert Sobiecki ◽  
Agnieszka Brojanowska ◽  
Konrad Kowalczyk
Keyword(s):  
Titanium Nitride ◽  
Calcium Ions ◽  
Biomedical Applications ◽  
Oxidation Potential ◽  
Plasma Oxidation ◽  
Corrosion Properties ◽  
Oxide Layers ◽  
Oxidation Processes ◽  
Oxidation Potentials ◽  
Electrolytic Plasma Oxidation

The article compares the corrosion properties of oxide layers formed on titanium nitride (obtained in glow-discharge nitriding) using electrolytic plasma oxidation. The corrosion properties are analysed in correlation with the surface morphology, microstructure and chemical composition of the layers. The oxidation processes were carried out in 10% and 25% phosphoric acid (V) solutions containing Ca2+ calcium ions. In each of these environments, oxide layers were formed using three oxidation potentials: 200V, 400V and 600 V. The oxidation potential and the concentration of acid and calcium ions in the oxidation solution was shown to affect the morphology of the surface and the corrosion properties of the oxide layers obtained.

Influences of Argon Atmosphere on Ceramic Coatings on Ti–6Al–4V Alloy by Micro-Plasma Oxidation in Different Solutions

2007 ◽  
Vol 546-549 ◽  
pp. 1717-1720
Author(s):  
Guo Dong Hao ◽  
Zhao Hua Jiang ◽  
Xiao Hong Wu ◽  
Yan Hua Cao
Keyword(s):  
Phase Composition ◽  
Ceramic Coatings ◽  
Argon Atmosphere ◽  
Element Content ◽  
Plasma Oxidation ◽  
Coating Surface ◽  
Better Than

Compound ceramic coatings were prepared on Ti-6Al-4V allosy by pulsed bi-polar Micro-plasma Oxidation (MPO) in NaAlO2(S1) and Na2SiO3(S2) solution respectively. The coated samples were calcined in argon under 1000 oC. The phase composition,morphology and element content of the ceramic coatings were investigated by XRD, SEM and XRF. After oxidation in argon, The Al2TiO5 of S1 coating surface was decomposed into Al2O3. SiO2 was crystalized in S2 coating with the final proportion of SiO2 to TiO2 on the coating surface is 81:18. The morphology of the ceramic coatings after the calcination was also different. S1 coatings calcined in argon were fine, grains and pores were smaller and were combined tightly with the substrate, on the contrary, S2 coatings calcined in argon cracked on the coating surface and were separated with the substrate. The content of elements in the coatings both changed a little, which may be due to the reaction of the substrate in the oxidation. According to the phase composition and the morphology of the coatings, S1 coatings are better than S2 coatings.

Microstructure and Mechanical Properties of Low Pressure Die Cast AM50 Magnesium Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 167-170 ◽  
Author(s):  
Li Ming Peng ◽  
Peng Huai Fu ◽  
Hai Yan Jiang ◽  
Chun Quan Zhai
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Die Casting ◽  
Low Pressure ◽  
Microstructure And Mechanical Properties ◽  
Heat Treated ◽  
Die Cast ◽  
Second Phases ◽  
Am50 Alloy ◽  
Pressure Die Casting

Compact AM50 alloy components were cast by Low Pressure Die Casting (LPDC) process. The microstructure and mechanical properties of cast components were investigated under as-cast and heat treated states. It was found that the microstructure of LPDC AM50 is composed of α-Mg and second phases - Mg17Al12 and Al8Mn5. Compared with Gravity die casting, LPDC AM50 alloy had much coarser grains and higher density, with smaller sizes and less content of second phases. The density of AM50 alloy by LPDC process was ρ=1.7836g/cm3, with increase of 0.45% based on Gravity die casting and much more increase compared with high pressure die casting. The as-cast mechanical properties by LPDC process were: σ0.2=57.8Mpa, σb=192.3Mpa, δ=8.7%. These of Gravity die casting were: σ0.2=53Mpa, σb=173.4Mpa, δ=8.1%. UTS in LPDC increased about 20MPa, with better YTS and Elongation. Compared with that of high pressure die cast AM50, the YTS of LPDC was much lower, with comparable UTS and Elongation. The mechanical properties of the heat treated AM50 alloy were still in the same level of as-cast state. AM50 alloy by LPDC process is not necessary subjected to tempering treatment.

A Comparison on Ceramic Coating Formed on AM50 Alloy by Micro-Arc Oxidation in Two Electrolytes

2007 ◽  
Vol 546-549 ◽  
pp. 575-578 ◽  
Author(s):  
Hui Zhao ◽  
Zhen Liu ◽  
Zhong Han
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Magnesium Alloy ◽  
Porous Layer ◽  
Barrier Layer ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Micro Arc Oxidation ◽  
Am50 Alloy ◽  
Phosphate Electrolyte

Characteristics of ceramic coatings on AM50 magnesium alloy by micro-arc oxidation in silicate and phosphate electrolytes have been investigated in this study. This study reveals that the thickness of the ceramic coatings increases with the treated time in both electrolytes, the growth rate of ceramic layer in phosphate is faster than that in silicate electrolyte. The surface roughness of the ceramic coating formed in phosphate electrolyte is higher than that formed in silicate electrolyte. The coatings formed in silicate, containing a thicker inner barrier layer and a thinner outer porous layer, consist of MgO, Mg2SiO4 and MgSiO3 phases. For the coatings formed in phosphate, the outer porous layer is thicker than the inner layer, it consist mainly of MgO and MgAlO4 phases.

Influence of cerium additions on the corrosion behaviour of high pressure die cast AM50 alloy

2012 ◽  
Vol 65 ◽  
pp. 145-151 ◽  
Author(s):  
Faruk Mert ◽  
Carsten Blawert ◽  
Karl Ulrich Kainer ◽  
Norbert Hort
Keyword(s):  
High Pressure ◽  
Corrosion Behaviour ◽  
Die Cast ◽  
Am50 Alloy
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