scholarly journals Comparative Study of Structures and Properties of Detonation Coatings with α-Al2O3 and γ-Al2O3 Main Phases

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1566
Author(s):  
Bauyrzhan Rakhadilov ◽  
Dauir Kakimzhanov ◽  
Daryn Baizhan ◽  
Gulnar Muslimanova ◽  
Sapargali Pazylbek ◽  
...  

This study is aimed at obtaining a coating of aluminum oxide containing α-Al2O3 as the main phase by detonation spraying, as well as a comparative study of the structural, tribological and mechanical properties of coatings with the main phases of α-Al2O3 and γ-Al2O3. It was experimentally revealed for the first time that the use of propane as a combustible gas and the optimization of the technological regime of detonation spraying leads to the formation of an aluminum oxide coating containing α-Al2O3 as the main phase. Tribological tests have shown that the coating with the main phase of α-Al2O3 has a low value of wear volume and coefficient of friction in comparison with the coating with the main phase of γ-Al2O3. It was also determined that the microhardness of the coating with the main phase of α-Al2O3 is 25% higher than that of the coatings with the main phase of γ-Al2O3. Erosion resistance tests have shown (evaluated by weight loss) that the coating with α-Al2O3 phase is erosion-resistant compared to the coating with γ-Al2O3 (seen by erosion craters). However, the coating with the main phase of γ-Al2O3 has a high value of adhesion strength, which is 2 times higher than that of the coating with the main phase of α-Al2O3. As the destruction of coatings by the primary phase, α-Al2O3 began at low loads than the coating with the main phase γ-Al2O3. The results obtained provide the prerequisites for the creation of wear-resistant, hard and durable layered coatings, in which the lower layer has the main phase of γ-Al2O3, and the upper layer has the main phase of α-Al2O3.

2021 ◽  
Vol 102 (2) ◽  
pp. 6-13
Author(s):  
N. Kantay ◽  
◽  
B.K. Rakhadilov ◽  
B. Tuyakbayev ◽  
A. Nabioldina ◽  
...  

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.


2020 ◽  
Vol 24 ◽  
pp. 975-982 ◽  
Author(s):  
C.R. Raghavendra ◽  
S. Basavarajappa ◽  
Irappa Sogalad ◽  
Siddaligayya Mathad

2013 ◽  
Vol 537 ◽  
pp. 7-11 ◽  
Author(s):  
Shu Hua Li ◽  
Yu Jun Yin ◽  
Da Wei Shen ◽  
Yuan Yuan Zu ◽  
Chang Zheng Qu

A dense ceramic oxide coating approximately 30µm thick was prepared on a Ly12 Al alloy by microarc oxidation in an alkali-silicate electrolytic solution. The morphology and microstructure were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Coating thickness and surface roughness (Ra) were measured after the coating had been synthesized. The tribological performance of the coatings was evaluated using a dry sand abrasion test and a solid particle erosion test. The results show that microarc oxidation coatings consist of the loose superficial layer and the inner dense layer. Both inner layer and out layer are composed of α-Al2O3 and γ-Al2O3, While the Al6Si2O3 phase is observed only in out loose layer. The average of the microhardness of the coating is 2096Hv.


2014 ◽  
Vol 8 (7) ◽  
pp. 663-667 ◽  
Author(s):  
David M. Fryauf ◽  
Junce Zhang ◽  
Kate J. Norris ◽  
Juan J. Diaz Leon ◽  
Michael M. Oye ◽  
...  

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