Structure and Thermophysical Properties of Coatings Formed by the Method of Microarc Oxidation on an Aluminum Alloy AK4-1

2018 ◽  
Vol 284 ◽  
pp. 1235-1241 ◽  
Author(s):  
N.Yu. Dudareva ◽  
A.B. Kruglov ◽  
R.F. Gallyamova
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Alloy ◽  
Methodological Approach ◽  
Microarc Oxidation ◽  
Layer By Layer ◽  
Properties Of Coatings ◽  
X Ray ◽  
Coefficient Of Thermal Conductivity ◽  
Pulsed Laser Heating

The work presents the results of investigation of the thermal conductivity of the coating formed by the method of microarc oxidation (MAO) on a deformable aluminum alloy AK4-1. The article describes the methodology of the research including the formation of the MAO layer, the study of the structure and composition of the coating and the determination of its coefficient of thermal conductivity. The methodological approach to determining the thermal conductivity is based on measuring the thermal diffusivity of the oxide layer by pulsed laser heating, as well as calculating the heat capacity and density of the coating based on the data of layer-by-layer X-ray phase analysis is proposed. During the calculations, the porosity of the coating was taken into account. In accordance with the proposed procedure, it is established that the MAO layer has a thermal conductivity coefficient of ~ 5 W/(mK). The value obtained is comparable with the known results, but is significantly lower than the values of the thermal conductivity of the single phases constituting the coating. It is assumed that this effect is related to the feature of the structure of the MAO layer.

scholarly journals Method for determining of the coatings thermophysical properties formed by the microarc oxidation

2019 ◽  
Vol 298 ◽  
pp. 00074
Author(s):  
Natalya Dudareva ◽  
Rida Gallyamova ◽  
Alexander Kruglov
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Laser Heating ◽  
Microarc Oxidation ◽  
Pulsed Laser ◽  
Layer By Layer ◽  
Thermophysical Parameters ◽  
Coefficient Of Thermal Conductivity ◽  
Volume Porosity ◽  
Pulsed Laser Heating

In this work are determined the thermophysical parameters (coefficient of thermal conductivity, thermal diffusivity and heat capacity) of a coating formed by the microarc oxidation (MAO) method on an aluminum alloy AK12D. A method for determining the thermal properties of the MAO layers was developed and verified. The technique is based on measuring the thermal conductivity of the layer by pulsed laser heating and calculating its heat capacity and density based on the data of layer-by-layer phase analysis taking into account the volume porosity. The method allows to calculate the thermophysical parameters whose values differ from the experimental no more than 2.2% in thermal conductivity and no more than 7.0% for heat capacity. In accordance with the proposed method, it was found that the MAO layer on AK12D alloy has a low thermal conductivity of ~ 1.57 W/(m·K) at 100 °C.

Effect of oxidation time on the microstructure and properties of ceramic coatings prepared by microarc oxidation on 7A04 superhard aluminum alloy

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744026
Author(s):  
Feng Xiao ◽  
Hui Chen ◽  
Jingguo Miao ◽  
Juan Du
Keyword(s):  
Aluminum Alloy ◽  
Microarc Oxidation ◽  
Ceramic Coatings ◽  
Ceramic Layer ◽  
X Ray Diffraction ◽  
Oxidation Treatment ◽  
X Ray ◽  
Metallurgical Bonding ◽  
Dense Ceramic ◽  
Morphology Of Surface

Under the sodium aluminates’ system, microarc oxidation treatment was conducted on the superhard aluminum alloy 7A04 for different times. The microstructure of microarc oxidation ceramic layer was investigated by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of different oxidation times on the adhesion strength of ceramic layer and substrate, the morphology of surface and cross-section, the phase composition and the electrochemical properties were studied. The results indicated that the connection of the coating and substrate appears to be metallurgical bonding and dense ceramic layer, and the surface is in a “volcanic vent” morphology, which is composed of [Formula: see text]-Al2O3 and little [Formula: see text]-Al2O3. The corrosion resistance of ceramic layer is improved significantly in contrast with that of the substrate.

Determination of the coefficient of thermal conductivity of glass and polymer fibers

1969 ◽  
Vol 26 (9) ◽  
pp. 523-526 ◽  
Author(s):  
O. F. Shlenskii ◽  
N. I. Goncharuk ◽  
V. Ya. Gal'tsov
Keyword(s):  
Thermal Conductivity ◽  
Polymer Fibers ◽  
Coefficient Of Thermal Conductivity

THE EFFECT OF TITANIA SOL IN PHOSPHATE ELECTROLYTE ON MICROARC OXIDATION COATINGS ON ALUMINUM ALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3190-3195 ◽  
Author(s):  
MING QI TANG ◽  
WEI PING LI ◽  
HUI CONG LIU ◽  
LI QUN ZHU
Keyword(s):  
Aluminum Alloy ◽  
Growth Process ◽  
Energy Dispersive Spectrometry ◽  
Microarc Oxidation ◽  
X Ray ◽  
Black Coating ◽  
Titania Sol ◽  
Thickness Meter ◽  
Scanning Electron ◽  
Phosphate Electrolyte

Black and gray microarc oxidation coatings have been obtained on 2A70 Aluminum alloy in phosphate electrolyte with and without titania sol, respectively. The growth process of the microarc oxidation coating in the electrolyte with titania sol was investigated. The coating was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray. The coating thickness was measured by eddy current thickness meter. The results show that the titania sol increase the growth rate of microarc oxidation coating. In both cases the composition of coatings contain Al and O , and are mainly composed of γ- Al 2 O 3 and AlPO 4. Compared with the gray coating, large amount of Ti is found on the surface of black coating. The titania sol added in the electrolyte results in Ti in the coating, in the form of TiO and Al 2 TiO 5.

scholarly journals Characteristics and properties of Bitlis ignimbrites and their environmental implications

2020 ◽  
Vol 70 (338) ◽  
pp. 214
Author(s):  
E. Işık ◽  
A. Büyüksaraç ◽  
E. Avşar ◽  
M. F. Kuluöztürk ◽  
M. Günay
Keyword(s):  
Thermal Conductivity ◽  
Construction Material ◽  
Metal Extraction ◽  
Ultrasonic Speed ◽  
Environmental Implications ◽  
Volcanic Origin ◽  
Speed Test ◽  
Subsequent Transformation ◽  
Coefficient Of Thermal Conductivity

Bitlis rock is used as a construction material and comes from the lava emitted by volcanoes and their subsequent transformation into ignimbrites. This type of rocks has been characterized physically, chemi­cally, toxicologically and radioactively using different procedures including determination of the coefficient of thermal conductivity, gamma spectrometry, ultrasonic speed test, ICP masses and metal extraction. The results indicate that Bitlis rocks have an ACI greater than 1, although their content of radon is lower than other rocks of volcanic origin. Leaching of metals from these rocks indicates that Pb and Cd can provide an infiltration level in the field higher than the level permitted by TCLP and they have undesired toxicological risks. The percent­ages of extraction of other metals also point to this infiltration problem. Despite this, the material offers good qualities for usage as a building material such as its thermal coefficients.

Corrosion Resistance of Al2O3-ZrO2 Composite Coating by Microarc Oxidation on 2A12 Aluminum Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 672-675
Author(s):  
Yu Hai Li ◽  
Yan Zhao ◽  
Bao Yi Li
Keyword(s):  
Aluminum Alloy ◽  
Composite Coating ◽  
Composite Coatings ◽  
Microarc Oxidation ◽  
Composite Ceramic ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
Mixed Electrolyte ◽  
X Ray ◽  
Thickness Meter

The Al2O3-ZrO2 composite ceramic coatings were prepared on 2A12 aluminum alloy by Microarc oxidation in the mixed electrolyte of 40g/L Na2SiO3 and 8g/L Na2WO4 solution containing different ZrO2 content particles. The thickness of the coatings was measured by an eddy current thickness meter. Microstructure and phase composition were analyzed by scanning election microscopy (SEM) and X-Ray diffraction (XRD), respectively. The experimental results show that ZrO2 in electrolyte can promote coatings growth; Al2O3-ZrO2 composite ceramic coatings consist of α-Al2O3, t-ZrO2, m-ZrO2, and ZrO2 is located in island-like discharge channels and does not destroy the integrity of composite coatings; There is scarcely any erosion on the surface of Al2O3-ZrO2 composite coatings because the intermediate product Zr(OH)4 could suppress composite coating corrosion.

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