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.

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 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 Effect of the detonation-spraying mode on the tribological properties of NiCr-Al2O3 coatings

2021 ◽  
Vol 5 (1) ◽  
pp. 39-44
Author(s):  
B.K. Rakhadilov ◽  
D.B. Buitkenov ◽  
E. Kabdykenova ◽  
Zh.B. Sagdoldina ◽  
L.G. Zhurerova
Keyword(s):  
Wear Resistance ◽  
Phase Composition ◽  
Tribological Properties ◽  
Volume Fraction ◽  
Oxygen Mixture ◽  
High Wear Resistance ◽  
Wear Volume ◽  
Detonation Spraying ◽  
Filling Volume ◽  
Study Results

The article presents the study results of detonation spraying parameters on the phase composition and tribological properties of NiCr-Al2O3 powder coatings. The spraying was carried out at a ratio of the acetylene-oxygen mixture O2 /C2H2=1.856. The detonation barrel filling volume with an explosive gas mixture varied from 30% to 68%. It is determined that the phase composition of the NiCr-Al2O3 coatings varies depending on the degree of detonation barrel filling. With an increase in the detonation barrel’s filling volume, the intensity of the NiCr diffraction peaks is decreased, and the intensity of the a-Al2O3 reflexes is increased, which indicates an increase in the content of the Al2O3 phase. When low filling volume, there is determined a low coating density and uneven roughness. The tribological test results showed that with an increase in the detonation barrel filling volume, there is a decrease in the wear volume, which confirms the increase in the coatings wear resistance. Determined that the lowest friction coefficient was recorded in the sample obtained at the barrel filling volume 68%. The coatings’ high wear resistance is associated with an increase in the alpha phase volume fraction of a-Al2O3 and coatings density.

Technology for the production of nanostructured coatings from nanoparticles of tungsten carbide and metal chromium

2020 ◽  
pp. 117-124
Author(s):  
T. I. Bobkova ◽  
R. Yu. Bystrov ◽  
A. A. Grigoriev ◽  
E. A. Samodelkin ◽  
B. V. Farmakovsky
Keyword(s):  
Tungsten Carbide ◽  
Composite Powder ◽  
Nanostructured Coatings ◽  
Powder Materials ◽  
Metallic Chromium ◽  
Complex Processes ◽  
Functionally Gradient ◽  
High Microhardness ◽  
Gradient Coatings ◽  
Technological Methods

This paper presents results of a study of complex processes for producing composite powder materials from tungsten carbide and metallic chromium. Technological methods for the formation of functionally gradient coatings with high microhardness up to 426 HV through microplasma spraying technology are disclosed.

Influence of Surface Condition on the Bonding Strength of Thermal Sprayed Coatings

1997 ◽  
Author(s):  
V.Yu. Ulianitsky ◽  
J.A. Nikolaev ◽  
T.P. Gavrilenko ◽  
M.C. Kim ◽  
J.W. Hong
Keyword(s):  
Bonding Strength ◽  
Substrate Surface ◽  
Surface Condition ◽  
Surface Preparation ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Substrate Material ◽  
Detonation Spraying ◽  
Wide Scale ◽  
Detonation Gun

Abstract The role of surface roughness in coating adhesion mechanism is studying for detonation spraying. Roughness was produced by conventional grit blasting, D-gun blasting and was formed as a result of spraying of high-adhesive thin layer of detonation coating. Cermet and alloy powders were sprayed by detonation gun Ob. The coating bonding strength measurements show the WC+25Co adhesion to be above 200 MPa independently of a substrate surface preparation. Contrary, NiCrSiB coatings are very sensitive to surface conditions their adhesion varies from 180 MPa to zero. As-sprayed alloy particles fail in adherence because of insufficient energy to fuse substrate material at a flat surface. Only developed (wide scale) roughness may be fused partially by these particles for their bonding to the substrate. Otherwise, high heated cermet particles do not need special surface preparation (except cleaning) for fusion of substrate material to provide high bonding with it. The wide scale and ball shape roughness, which is similar to the self-reproduced coating roughness, provides the best conditions for the coating bonding and it is recommended as the purpose of surface treatment before thermal spray coating.

Detonation Spraying of TiO2 -Ag: Controlling the Phase Composition and Microstructure of the Coatings

2012 ◽  
pp. 161-169 ◽  
Author(s):  
Dina V. Dudina ◽  
Sergey B. Zlobin ◽  
Vladimir Yu. Ulianitsky ◽  
Oleg I. Lomovsky ◽  
Natalia V. Bulina ◽  
...  
Keyword(s):  
Phase Composition ◽  
Detonation Spraying

Variability and repeatability of olfactometric results of n-butanol, pig odour and a synthetic gas mixture

2004 ◽  
Vol 50 (4) ◽  
pp. 65-73 ◽  
Author(s):  
N. Defoer ◽  
H. Van Langenhove
Keyword(s):  
Synthetic Mixture ◽  
Gas Mixture ◽  
Mixture Ratio ◽  
Air Samples ◽  
Complete Dataset ◽  
Synthetic Gas ◽  
Pig Farms ◽  
The Mean ◽  
The One ◽  
Mean Variance

For the purposes of a research project for the Flemish authorities, olfactometric measurements were carried out at six closed pig farms and six fattener farms. The results of these olfactometric measurements were compared with the olfactometric results of n-butanol samples and samples of a synthetic gas mixture of ethanethiol, methylacetate and 2-propanol in nitrogen, both analysed on the same days as the air samples from the pig farms. The results of the n-butanol tests for all panellists showed that nobody was qualified according to the CEN criteria, and that, consequently, these criteria are rather stringent. Comparing the variability of the results for the three different odours showed that the mean and standard deviation of the mean variance were not significantly different for the three odour types, which means that the repeatability of the panellist results was equal for the examined odour types. The principle of traceability was checked by comparing the variance of the n-butanol, pig odour and synthetic mixture ratio. For the complete dataset, the principle of traceability could not been proven for n-butanol. For the restricted dataset, the principle of traceability was more valid for n-butanol than for the mixture, but differences were small. Finally, normalization was looked for with regard to olfactometric measurements of air samples from pig farms based either on n-butanol or on the synthetic mixture. Both models had low determination coefficients, but the model based on the synthetic mixture gave better results than the one based on n-butanol.

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