EFFECTS OF YTTRIUM NITRATE ON MICROSTRUCTURE AND HIGH TEMPERATURE RESISTANCE OF ZrO2–Y2O3 CERAMIC COATINGS PREPARED BY A MODIFIED PEO PROCESS ON AN Al–12Si ALLOY

2017 ◽  
Vol 24 (Supp02) ◽  
pp. 1850026
Author(s):  
WANG PING ◽  
ZHOU LIGUO ◽  
HAN JING ◽  
GUO YONGCHUN
Keyword(s):  
High Temperature ◽  
Salt Solution ◽  
High Temperature Oxidation ◽  
Fine Particles ◽  
Heat Insulation ◽  
Ceramic Coatings ◽  
Coated Sample ◽  
Yttrium Nitrate ◽  
Temperature Oxidation ◽  
Weight Gains

A ZrO2–Al2O3 ceramic coating and YSZ–Al2O3 coating were prepared on ZAlSil2Cu3Ni2 alloys by a modified plasma electrolytic oxidation (PEO) in zirconium salt solution. The microstructure, heat-insulating and high temperature oxidation properties were investigated by SEM, XRD and a fabricated heat insulation temperature testing device. The results showed that the surface of the YSZ–Al2O3 coating was composed of fine particles and had lower roughness. Yttrium partially stabilized the zirconia solid solution (Y[Formula: see text]Zr[Formula: see text]O[Formula: see text] which was formed in zirconium yttrium salt solution with a higher reaction temperature. The growth rate of the YSZ–Al2O3 coating was greater than the ZrO2–Al2O3 coating. Especially, the outward growth obviously improves. Furthermore, the heat insulation property of the coating enhances. The curves of the weight gains in the sample with YSZ–Al2O3 coating showed a logarithmic shape under the high temperature oxidation treatment of 400[Formula: see text]C. The weight gains of the sample with YSZ–Al2O3 coating were relatively lower than that of the as-coated sample. The ceramic layer had good high temperature stability.

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.

High Temperature Oxidation Behavior of (Ti, Al) C Ceramic Coatings on Carbon Steel Prepared by Electrical Discharge Coating in Kerosene

2011 ◽  
Vol 189-193 ◽  
pp. 186-192 ◽  
Author(s):  
Guo Liang Li ◽  
Xiao Hua Jie ◽  
Ling He
Keyword(s):  
High Temperature ◽  
Carbon Steel ◽  
Electrical Discharge ◽  
High Temperature Oxidation ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Compact Structure ◽  
Temperature Oxidation ◽  
Before And After ◽  
High Temperature Oxidation Behavior

Multi-component metal ceramic coating（Ti, Al）C was prepared on the 0.45% carbon steel by electrical discharge coating (EDC) in a hydrocarbon medium. The coating of the samples before and after oxidation was analyzed by different methods including X-ray diffraction (XRD), scanning electron spectroscopy (SEM) and energy disperse spectroscopy (EDS).The thermogravimetric technique was used to approximate the kinetics of oxidation of the coated and the uncoated samples.The results indicated that the thickness of the coating was about 20μm, and the composition of the ceramic coating mainly consisted of (Ti, Al) C and a little Ti3AlC. An oxide film with compact structure formed after 600°C oxidation for 200h, and it was mainly composed of Al2O3and TiO2, which inhibited further oxygen diffusion into the coating. The (Ti, Al) C ceramic coating possessed slow oxidation rate and high temperature oxidation resistance.

Influences of Different Calcinations Ambience on Phase Composition and Morphologies of Ceramic Coatings on Ti Alloy by Micro-Arc Oxidation

2010 ◽  
Vol 97-101 ◽  
pp. 1554-1557
Author(s):  
Guo Dong Hao ◽  
Nai Wu Zhang ◽  
Tao Yun ◽  
Jin Wang ◽  
Bo Lian ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature Oxidation ◽  
Ceramic Coatings ◽  
Ti Alloy ◽  
Temperature Oxidation ◽  
Weight Gains ◽  
Micro Arc Oxidation ◽  
Oxidation Properties ◽  
Α Al2o3

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in a NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface morphology of the ceramic coatings were investigated by XRD, SEM and XRF. The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 was decomposed very soon and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 was decomposed very slowly in argon and the final coating surface was completely α-Al2O3. Also, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were fined; grains and pores were smaller than those in air. High temperature oxidation occurred very strongly in the TC4 substrate, the weight gains of the as-coated ceramic coatings and the treated ones in argon were nearly changing in the form of parabola, and the weight gains of the coated samples treated in argon were comparatively lower than those of the as-coated samples.

Study on Microstructure and High Temperature Oxidation Resistance of Laser Cladding Coating Prepared by Ni60-TiO2-B4C-Al Powders

2014 ◽  
Vol 488-489 ◽  
pp. 201-204
Author(s):  
Fang Zhou ◽  
Hui Yao Yang ◽  
Liang Hua He
Keyword(s):  
High Temperature ◽  
Composite Coating ◽  
Oxidation Resistance ◽  
Laser Cladding ◽  
High Temperature Oxidation ◽  
Fine Particles ◽  
Substrate Material ◽  
Temperature Oxidation ◽  
Metal Atoms ◽  
Metallurgical Bond

The composite coating with TiC-TiB2-Ni3Al was fabricated on 45 steel by laser cladding. The microstructure and high temperature oxidation resistance of coating were investigated. The results show that, the main phases of coating are α-Fe, TiC, TiB2, Ni3Al, (Fe,Cr)7C3 and Al2O3. The interface of coating and substrate material is metallurgical bond; the coating is uniform and dense without cracks and pores. The fine particles of TiC and TiB2 disperse uniformly in the coating. After oxidized at 1000°C for 60 h, the oxidation film is consisted of spherical oxides of Al, Ti and Cr, they can hinder the diffusion between oxygen and metal atoms and make the coating possess outstanding high temperature oxidation resistance.

High Temperature Oxidation Effect on the Dissolution Rate of Hot-Dip Aluminized Steel in Aluminum Melt

2014 ◽  
Vol 970 ◽  
pp. 248-251
Author(s):  
Ayeh Mohsenifar ◽  
Mohammad Reza Aboutalebi ◽  
S. Hossein Seyedein
Keyword(s):  
High Temperature ◽  
Dissolution Rate ◽  
High Temperature Oxidation ◽  
Molten Aluminum ◽  
Low Carbon Steel ◽  
Isothermal Oxidation ◽  
Coated Sample ◽  
Low Carbon ◽  
Temperature Oxidation ◽  
Oxidation In Air

Hot dip aluminizing of low carbon steel followed by high temperature oxidation in air was carried out to evaluate the dissolution rate of coated sample in molten aluminum. The microstructure of oxide and aluminide layers was investigated using scanning electron microscopy and X-ray diffraction methods. The characterization of the coating showed that Fe2Al5 has been the major phase formed on the surface of specimen before high temperature oxidation. Isothermal oxidation of the coating as resulted in the formation of Al2O3 while Fe2Al5 phase transformed into FeAl and Fe3Al phases. The coated samples were further subjected to corrosion in molten aluminum. It was proved that the oxide layer formed on the coating and developed FeAl and Fe3Al intermetallic phases play the major role in protecting the specimen from corrosion in molten aluminum.

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