scholarly journals Influence of Detonation-Spraying Parameters on the Phase Composition and Tribological Properties of Al2O3 Coatings

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 793
Author(s):  
Nurgamit Kantay ◽  
Bauyrzhan Rakhadilov ◽  
Sherzod Kurbanbekov ◽  
Didar Yeskermessov ◽  
Gulnara Yerbolatova ◽  
...  
Keyword(s):  
Phase Composition ◽  
X Ray Diffraction ◽  
Technological Parameters ◽  
Detonation Spraying ◽  
Spraying Parameters ◽  
Detonation Method ◽  
Al2o3 Phase ◽  
Detonation Gun ◽  
Α Al2o3 ◽  
Degree Of Filling

Al2O3 coatings were applied on the surface of 12Ch18N10T steel by the detonation method at different degrees of filling of the detonation gun. The aim was to study the influence of technological parameters on the formation of the coating’s structure, phase composition and tribological characteristics. The degree of filling the gun with a gas mixture (C2H2/O2) varied from 53% to 68%. X-ray diffraction study showed that the content of α-Al2O3 increases depending on the degree of filling. The results showed that the hardness increases with an increase in the α-Al2O3 phase. When the gun is 53% filled with gas, the Al2O3-based coating has the hardness of 20.56 GPa compared to 58%, 63% and 68% fillings. Tribology tests have shown that the wear rate and friction coefficient of the coating is highly dependent on the degree of filling of the gun.

scholarly journals Obtaining multilayer coatings by the detonation spraying method

2021 ◽  
Vol 5 (2) ◽  
pp. 148-154
Author(s):  
D.N. Kakimzhanov ◽  
B.K. Rakhadilov ◽  
D.B. Buitkenov ◽  
L.G. Zhurerova ◽  
M.K. Rakhadilov ◽  
...  
Keyword(s):  
Phase Composition ◽  
Multilayer Coating ◽  
Gas Mixture ◽  
Multilayer Coatings ◽  
Al2o3 Coating ◽  
Technological Parameters ◽  
Detonation Spraying ◽  
Al2o3 Phase ◽  
Degree Of Filling ◽  
Spraying Method

This work were studied the effect of technological parameters of detonation spraying on the phase composition and tribological characteristics on the bases of NiCr and Al2O3 coatings. As well as there was obtained and investigated multilayer coating on the bases of NiCr/NiCr- Al2O3/Al2O3 . It was determined that during detonation spraying the phase composition of Al2O3 coatings strongly depends on the degree of filling the borehole with a gas mixture. The a - Al2O3 -phase content in the coatings increases when the degree of filling is 63% and 54%. Only one CrNi3 phase is observed on the diffractograms and only increase of reflex intensity (020) at barrel filling by 58% is observed by sputtering on the bases of NiCr coatings in different degrees of barrel filling. The results of the coating nanohardness study showed that the hardness of the Al2O3 coating increases depending on the content of a- Al2O3 in it. Al2O3 coating has the maximum nanohardness values and is 16.42 GPa at the borehole is filled to 63%. The nanohardness of NiCr coating has the maximum values at barrel filling by 58% and consisting of 8.02 GPa.

scholarly journals Obtaining functional gradient coatings based on Al2O3 by detonation spraying

2020 ◽  
Vol 100 (4) ◽  
pp. 22-27
Author(s):  
B.K. Rakhadilov ◽  
◽  
A.B. Nugumanova ◽  
P. Kowalewski ◽  
M.K. Kylyshkanov ◽  
...  
Keyword(s):  
Delay Time ◽  
Volume Fraction ◽  
Secondary Recrystallization ◽  
High Hardness ◽  
X Ray Diffraction ◽  
Detonation Spraying ◽  
X Ray ◽  
Elastic Module ◽  
Al2o3 Phase ◽  
Α Al2o3

The article deals with the phase composition and hardness of Al2O3 coatings obtained by detonation spraying. It was found that a decrease in the delay time between shots is leading to an increase in the hardness and elastic module of Al2O3 coatings. It was found based on X-ray diffraction analysis that the main reason for the increase in hardness with a decreasing in the delay time between shots is associated with increases in the volume fraction of α- Al2O3 phase. A high content of the more ductile γ-Al2O3 phase at the substrate-coating interface leads to an increase in adhesion characteristics, and a high content of the α-Al2O3 phase on the coating surface provides high hardness and wear resistance. The studies of X-ray diffraction presented that the highest phase content is achieved when the coatings are formed with a delay time between shots of 0.25 s. It was found that increase in the volume fraction of the α-Al2O3 phase is caused by the secondary recrystallization γ → α, which occurs due to the heating of particles during coating formation, i.e. due to increase in temperature above 1100 ºС in single spots of the coating when they are put each other

scholarly journals Tribological wear of Fe-Al coatings applied by gas detonation spraying

2021 ◽  
Author(s):  
Tomasz Chrostek
Keyword(s):  
Dry Friction ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Detonation Spraying ◽  
Gas Detonation ◽  
Compressive Stresses ◽  
Spraying Parameters ◽  
Thin Oxide Films ◽  
Pin On Disc ◽  
The Coefficient Of Friction

Comparative tests of gas detonation (GDS) coatings were carried out in order to investigate the influence of spraying parameters on abrasive wear under dry friction conditions. The tests were carried out using the pin-on-disc (PoD) method at room temperature. The microstructure of the coatings was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM / EDS) methods. The results showed that with specific GDS process parameters, the main phases in both coatings were FeAl and Fe3Al involving thin oxide films Al2O3. The tribological tests proved that the coatings sprayed with the shorter barrel of the GDS gun showed higher wear resistance. The coefficient of friction was slightly lower in the case of coatings sprayed with the longer barrel of the GDS gun. During dry friction, oxide layers form on the surface, which act as a solid lubricant. The load applied to the samples during the tests causes shear stresses, thus increasing the wear of the coatings. During friction, the surface of the coatings is subjected to alternating tensile and compressive stresses, which lead to delamination and is the main wear mechanism of the coatings.

scholarly journals Phase composition of coatings on the D16 alloy during micro-arc oxdation in alkaline and silicate electrolytes

2020 ◽  
Vol 1,2020 (1,2020 (124)) ◽  
pp. 51-55
Author(s):  
Subbotina V ◽  
Belozerov V ◽  
Sobol’ O
Keyword(s):  
Phase Composition ◽  
Liquid Glass ◽  
Amorphous State ◽  
Practical Significance ◽  
Alkaline Electrolyte ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Coating Formation ◽  
Al2o3 Phase ◽  
Α Al2o3

Goal. The influence of electrolysis conditions at different electrolyte compositions on the phase formation of coatings obtained by micro-arc oxidation (MDO) on an aluminum alloy D16 was studied. Method. For electrolysis, two types of electrolytes were used: alkaline electrolyte (solution (KOH) in distilled water), silicate electrolyte (with different percentages of Na2SiO3 component). Research results. It was found that the phase composition of the MAO coatings obtained in an alkaline (KOH) electrolyte mainly consists of γ - Al2O3 phases and, to a much lesser extent, the α-Al2O3 phases. An increase in the KOH concentration leads to a shift in the γ – Al2O3 → α – Al2O3 polymorphic reaction toward the formation of the hardest α-Al2O3 phase (corundum). The formation of the preferred orientation of the growth of crystallites of γ – Al2O3 and α – Al2O3 phases during their formation in an alkaline electrolyte was not detected. Scientific novelty. A significant influence on the mechanism and processes of coating formation is made by the addition of liquid glass (Na2SiO3) in the electrolyte. In this case, the growth rate of the coating increases significantly, but the size of the ordering regions decreases from crystalline to X-ray amorphous. The phase composition of the MAO coatings, when they are formed in a silicate electrolyte, varies from a mixture of the γ - Al2O3 phase and mullite (3Al2O3 • 2SiO2) with a low content of liquid glass (10 g/l Na2SiO3) to the formation of only the X-ray amorphous phase with a high content of liquid glass in the electrolyte (50 g/l Na2SiO3). Practical significance. It was concluded that the use of an alkaline or silicate electrolyte with different percentages allows a wide variation of both the phase composition and structural state (α- Al2O3 and γ- Al2O3 phases, mullite (3Al2O3 • 2SiO2) or X-ray amorphous state) and the kinetics of growth the coating itself.

EFFECTS OF α-Al2O3 NANOADDITIVE ON THE PROPERTIES OF CERAMIC COATINGS PREPARED IN BORATE ELECTROLYTE BY MICRO-ARC OXIDATION

2012 ◽  
Vol 19 (04) ◽  
pp. 1250038 ◽  
Author(s):  
H. X. LI ◽  
H. H. ZHU ◽  
X. WU ◽  
Z. G. JI
Keyword(s):  
Phase Composition ◽  
Great Influence ◽  
Ceramic Coatings ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Micro Arc Oxidation ◽  
Edx Analyses ◽  
6063 Aluminum Alloy ◽  
Α Al2o3 ◽  
Wear Tests

Ceramic coatings have been synthesized on 6063 aluminum alloy by micro-arc oxidation (MAO) technique in the solution of Na2B4O7 electrolyte with and without α- Al2O3 nanoadditive. Effects of α- Al2O3 nanoadditive on the phase composition, micro-structure, micro-hardness, adhesion and wear resistance of the prepared ceramic coatings have been investigated in this paper. The phase composition and microstructure of the MAO coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDX) analyses, respectively. Micro-hardness, adhesion and tribological and wear tests were also performed. The results showed that the α- Al2O3 nanoadditive doped in the electrolyte had great influence on the structural and mechanical properties of the ceramic coatings.

scholarly journals Effect of Heat Treatment on the Microstructure and Phase Composition of ZrB2–MoSi2 Coating

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 779
Author(s):  
Marina Kovaleva ◽  
Igor Goncharov ◽  
Vseslav Novikov ◽  
Maxim Yapryntsev ◽  
Olga Vagina ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Lamellar Structure ◽  
Carbon Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mosi2 Coating ◽  
Α Al2o3 ◽  
Sprayed Coating ◽  
Scanning Electron

Composite ZrB2–MoSi2 coating modified by Y2O3 and Al was prepared by a new multi-chamber detonation accelerator (MCDS) on carbon/carbon composites. Postdeposition heat treatment of the samples at 1500 °C for 1 and 6 h was carried out in air. The effect of heat treatment on the microstructure and phase composition of the ZrB2–MoSi2 coating was investigated by scanning electron microscopy and X-ray diffraction phase analysis. The as-sprayed coating presented as a dense lamellar structure, composed of m-ZrO2, t-ZrO2, some hexagonal ZrB2, and cubic Al phases. The m-ZrO2, c-ZrO2, and h-(α-Al2O3) formed at 1500 °C. The coatings after heat treatment (1 and 6 h) exhibited a structure without cracks. The porosity (~1%) of the coating did not change after heat treatment. Thin, continuous, silica-rich film covered the surfaces of ZrO2 and Al2O3 particles, and could have played a role during heat treatment by acting as a grain lubricant for particle rearrangement.

scholarly journals Influence of pulsed plasma treatment on phase composition and hardness of Cr3C2-NiCr coatings

2021 ◽  
Vol 5 (1) ◽  
pp. 45-51
Author(s):  
D.N. Kakimzhanov ◽  
B.K. Rakhadilov ◽  
Yu.N. Tyurin ◽  
O.V. Kolisnichenko ◽  
L.G. Zhurerova ◽  
...  
Keyword(s):  
Phase Composition ◽  
Plasma Treatment ◽  
Physical And Mechanical Properties ◽  
Oxide Phase ◽  
Mechanical Tests ◽  
Pulse Plasma ◽  
Pulsed Plasma ◽  
X Ray Diffraction ◽  
Detonation Spraying ◽  
Carbide Particles

In this study, the research results of the influence of pulsed plasma treatment on phase composition, hardness, and roughness of Cr3C2-NiCr coatings are presented. The Cr3C2-NiCr coating was applied to substrate 12Kh18N10T stainless steel by detonation spraying method. To change the physical and mechanical properties of sprayed coating’s surface layers, subsequent pulse-plasma treatment was used. The pulse-plasma treatment leads to changing the roughness of Cr3C2-NiCr coating. The results of mechanical tests showed that after pulsed plasma treatment, the hardness of Cr3C2-NiCr coating is increased. Based on X-ray diffraction analysis, it was found that the hardness increasing of coating is associated with phase transformations on the surface layer, in particular, the formation of the oxide phase and an increase in the number of carbide particles.

Research of annealing influence on the hardness of detonation coatings from aluminum oxide

2021 ◽  
Vol 102 (2) ◽  
pp. 6-13
Author(s):  
N. Kantay ◽  
◽  
B.K. Rakhadilov ◽  
B. Tuyakbayev ◽  
A. Nabioldina ◽  
...  
Keyword(s):  
Aluminum Oxide ◽  
Volume Fraction ◽  
High Strength ◽  
Oxide Coating ◽  
Alumina Coating ◽  
Alumina Powder ◽  
Detonation Spraying ◽  
Before And After ◽  
Al2o3 Phase ◽  
Α Al2o3

The article examines the effect of annealing on the structure and properties of alumina-based coatings obtained by detonation spraying. Coated samples were kept separately at temperatures of 500, 700, 800 and 1200 °C at a pressure of 3.6*10-4 Pa for more than 1 hour. It was found that the microhardness of coatings made of alumina increases by 15-30 % after annealing depending on annealing temperature. The results of nanoindentation show that at 1200 °C the nanohardness of coatings after annealing increases by almost 100%. Aluminum oxide coating is characterized by high strength and density of the coating before and after annealing, and slight porosity. Results of X-ray analysis showed that the alumina powder consists of α-Al2O3 lattice, and after detonation injection coating cubes are converted into a semi-γ-cubic lattice. It was found that during the annealing of the coating at 1200 °C all cells of γ-phase completely transit to the α-phase. It was found that the increase in hardness after annealing of alumina coating at 500, 700, 800 and 1200 °C is associated with an increase in volume fraction of α-Al2O3 phase.

Microstructural Evolution of Slurry Fe Aluminide Coatings during High Temperature Steam Oxidation

2008 ◽  
Vol 595-598 ◽  
pp. 251-259 ◽  
Author(s):  
Alina Agüero ◽  
Krystina Spiradek ◽  
S. Höfinger ◽  
Marcos Gutiérrez ◽  
Raúl Muelas
Keyword(s):  
Protective Layer ◽  
Steam Oxidation ◽  
X Ray Diffraction ◽  
Steam Power ◽  
Aluminide Coatings ◽  
Transmission Electron ◽  
Al2o3 Phase ◽  
High Temperature Steam ◽  
Α Al2o3 ◽  
New Generation

Slurry iron aluminide coatings are very resistant to steam oxidation at 600-650º C. These coatings can be used to protect new generation Ultra Super Critical (USC) steam power plant ferritic/martensitic steel components. The microstructure of the initially deposited coating changes as a function of time, mainly due to coating-substrate interdiffusion, going from mostly Fe2Al5 to FeAl, causing the precipitation of AlN in those substrates containing a minimum content of N and moreover, developing Kirkendall porosity at the coating-substrate interface. Steam oxidation at 650º C causes the formation of a protective thin layer of hexagonal χ-Al2O3 phase along with some α- and γ-Al2O3 after the first few hours of exposure. However, despite the relatively low temperature, and after several thousands hours the protective layer was mostly composed of α-Al2O3. A study of the evolution of the microstructure of slurry aluminide coatings deposited on P92 and exposed to steam at 650º C has been carried out by scanning and transmission electron microscopy and X ray diffraction.

scholarly journals Preparation and Characterization of NiCr/NiCr-Al2O3/Al2O3 Multilayer Gradient Coatings by Gas Detonation Spraying

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1524
Author(s):  
Bauyrzhan Rakhadilov ◽  
Dastan Buitkenov ◽  
Zhuldyz Sagdoldina ◽  
Zhanat Idrisheva ◽  
Manira Zhamanbayeva ◽  
...  
Keyword(s):  
Phase Composition ◽  
Ceramic Layer ◽  
Oxygen Mixture ◽  
Gas Mixture ◽  
Powder Materials ◽  
Detonation Spraying ◽  
Mixture Ratio ◽  
Gun Barrel ◽  
Detonation Gun ◽  
Gradient Coatings

This paper investigates the influence of the technological parameters of detonation spraying on the phase composition of NiCr- and Al2O3-based coatings. It was determined that the phase composition of Al2O3 coatings during detonation spraying strongly depends on the barrel filling volume with the gas mixture. The acetylene–oxygen mixture, which is the most frequently used fuel in the detonation spraying of powder materials, was used as a fuel gas. To obtain a ceramic layer based on Al2O3, spraying was performed at an acetylene–oxygen O2/C2H2 mixture ratio of 1.856; the volume of filling of the detonation gun barrel with an explosive gas mixture was 63%. To obtain a NiCr-based metallic layer, spraying was performed at the O2/C2H2 ratio of 1.063; the volume of filling of the detonation gun barrel with an explosive gas mixture was 54%. Based on a study of the effect of the detonation spraying mode on the phase composition of NiCr and Al2O3 coatings, NiCr/NiCr-Al2O3/Al2O3-based multilayer coatings were obtained. Mixtures of NiCr/Al2O3 powders with different component ratios were used to obtain multilayer gradient coatings. The structural-phase composition, mechanical and tribological properties of multilayer gradient metal–ceramic coatings in which the content of the ceramic phase changes smoothly along the depth were experimentally investigated. Three-, five- and six-layer gradient coatings were obtained by alternating metallic (NiCr) and ceramic (Al2O3) layers. The phase composition of all coatings was found to correspond to the removal of information from a depth of 20–30 μm. It was determined that the five-layer gradient coating, consisting of the lower metal layer (NiCr), the upper ceramic layer (Al2O3) and the transition layer of the mechanical mixture of metal and ceramics, is characterized by significantly higher hardness (15.9 GPa), wear resistance and adhesion strength.

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