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.

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 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 ◽  
...  
Keyword(s):  
Aluminum Oxide ◽  
Comparative Study ◽  
Lower Layer ◽  
Oxide Coating ◽  
Primary Phase ◽  
Main Phase ◽  
Wear Volume ◽  
Detonation Spraying ◽  
Properties Of Coatings ◽  
Α Al2o3

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.

scholarly journals Improvement of Plasma Resistance of Anodic Aluminum-Oxide Film in Sulfuric Acid Containing Cerium(IV) Ion

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 103 ◽  
Author(s):  
Jongho So ◽  
Eunmi Choi ◽  
Jin-Tae Kim ◽  
Jae-Soo Shin ◽  
Je-Boem Song ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Aluminum Oxide ◽  
Anodic Aluminum Oxide ◽  
Etching Rate ◽  
Ion Concentration ◽  
Anodic Aluminum Oxide Film ◽  
Anodic Aluminum ◽  
Plasma Resistance ◽  
Al2o3 Phase ◽  
Α Al2o3

The parts of equipment in a process chamber for semiconductors are protected with an anodic aluminum-oxide (AAO) film to prevent plasma corrosion. We added cerium(IV) ions to sulfuric acid in the anodizing of an AAO film to improve the plasma corrosion resistance, and confirmed that the AAO film thickness increased by up to ~20% when using 3 mM cerium(IV) ions compared with general anodizing. The α-Al2O3 phase increased with increasing cerium(IV) ion concentration. The breakdown voltage and etching rate improved to ~35% and 40%, respectively. The film’s performance regarding the generation of contamination particles reduced by ~50%.

Performance of Polypropylene Fiber and Rubber Powder Improved High Strength Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 403-408
Author(s):  
Feng Liu ◽  
Jiang Zhu ◽  
Zhou Li Wen ◽  
Li Juan Li
Keyword(s):  
High Strength Concrete ◽  
Volume Fraction ◽  
Rubber Particle ◽  
Polypropylene Fiber ◽  
High Strength ◽  
Strength Concrete ◽  
Investigation Methods ◽  
Spalling Failure ◽  
Rubber Particles ◽  
Before And After

Based on high strength concrete (HSC), the improved HSC concrete was produced by adding different contents of fine grain rubber particles and polypropylene fibers. The grain size of the rubber particle is 420 m and the rubber content is 1%, 2%, and 3% of the mass of cementitious material respectively. The volume fraction of polypropylene fiber is 0.1%.The performance of HSC, rubber particle improved high strength concrete (RHSC), polypropylene fiber improved high strength concrete (PHSC) and polypropylene fiber hybrid rubber particle improved high strength concrete (PRHSC) before and after high temperature are studied. The investigation methods used are the external surface inspection, weight loss and residual strength testing. The experimental results show that rubber particles can improve the workability of HSC and PHSC under normal temperature. Polypropylene fiber can significantly improve the spalling failure resistance property of HSC and RHSC.

Microstructure and Mechanical Properties of High Strength Al2O3p/6061Al Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1390-1393
Author(s):  
Bai Feng Luan ◽  
Gao Hui Wu ◽  
Qing Liu ◽  
Niels Hansen ◽  
Ting Quan Lei
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Hot Extrusion ◽  
High Strength ◽  
Dispersion Strengthening ◽  
Particle Volume ◽  
Microstructure And Mechanical Properties ◽  
Before And After

An experimental study of microstructure and mechanical properties in the Al2O3 particulate reinforced 6061 Aluminum composites has been used to determine the effect of extrusion and particle volume fraction (20, 26, 30, 40, 50, 60%Vf) in deformed metal matrix composites. The microstructure of Al2O3 /6061Al composite before and after hot extrusion is investigated by TEM and SEM. Results show that dislocation and subgrain generated after hot extrusion as well as the particle distribution of composite become more uniform with extrusion ratio of 10:1. The ultimate strength, yield strength and elongation of the composite also increase after hot extrusion. Dispersion strengthening and subgrain boundary strengthening is discussed and also the effect of precipitate introduced by heat treatment both after casting and after extrusion. The yield stress (0.2% offset) of the composites has been calculated and predicted using a standard dislocation hardening model. Whilst the correlation between this and the measured value of yield stress obtained in previous experimental test is reasonable.

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.

TRIP Effect in a Hot-Rolled Low-Carbon High Strength Complex Phase Steel

2014 ◽  
Vol 788 ◽  
pp. 267-271
Author(s):  
Xiao Dong Tan ◽  
Zi Quan Liu ◽  
Yun Bo Xu ◽  
Xiao Long Yang ◽  
Di Wu
Keyword(s):  
Electron Microscope ◽  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Rolling Process ◽  
Optical Microscope ◽  
Trip Effect ◽  
Low Carbon ◽  
Electron Backscattered Diffraction ◽  
Before And After

In the present work, a study has been made of the hot-rolling process for a transformation induced plasticity (TRIP) steel Fe-0.12C-0.5Si-1.4Mn-0.5Cr (wt%). The volume fractions of retained austenite before and after a deformation were determined by X-ray diffraction (XRD). The microstructure was characterized by optical microscope, scanning electron microscope (SEM) equipped with electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). A uniaxial tension text indicated that the steel possesses ultimate tensile strength of 748 MPa with yield ratio of 0.7 and elongation of 20%. The steel with the volume fraction of retained austenite of 12.5 % exhibits significant TRIP effect.

Suspension Spraying Tip: High Molecular Weight Solvent

2021 ◽  
Author(s):  
Jan Cizek ◽  
Radek Musalek ◽  
Jan Medricky ◽  
Tomas Tesar ◽  
Frantisek Lukac ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Model Material ◽  
Alumina Powder ◽  
Suspension Spraying ◽  
Dense Microstructure ◽  
Solid Load ◽  
Potential Alternative ◽  
Al2o3 Phase ◽  
Α Al2o3

Abstract In suspension spraying, the two most frequently used solvents are water and ethanol. In this study, we test a potential alternative, a high-molecular weight solvent. Two organic solvents are compared: ethanol (serving as a benchmark, suspension formulated at 10 wt.% solid load) and di-propylene glycol methyl ether (two suspensions at 10 wt.% and 20 wt.%). Submicron alpha-alumina powder is used as a model material to formulate the suspensions. It is shown that ethanol- and ether-based-feedstock coatings are fully comparable in terms of their microstructure, porosity content, surface roughness, and hardness. However, the ether-based coatings exhibit slightly higher levels of α-Al2O3 phase than their ethanol-based counterpart (17 wt.% vs. 6 wt.%). The use of 20 wt.% solid load in the ether solvent leads to a twofold increase in the deposition rate while, as opposed to ethanol, successfully retaining a dense microstructure. Ether also costs less than ethanol and is safer to handle.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

In vitro Behaviour of Alumina-Hydroxiapatite Composites Coatings

2018 ◽  
Vol 69 (6) ◽  
pp. 1416-1418
Author(s):  
Alexandru Szabo ◽  
Ilare Bordeasu ◽  
Ion Dragos Utu ◽  
Ion Mitelea
Keyword(s):  
Pure Titanium ◽  
Titanium Substrate ◽  
High Strength ◽  
Biological Properties ◽  
Commercially Pure Titanium ◽  
Hvof Spraying ◽  
Before And After ◽  
Sbf Solution ◽  
Oxygen Fuel

Hydroxyapatite (HA) is a very common material used for biomedical applications. Usually, in order to improve its poor mechanical properties is combined or coated with other high-strength materials.The present paper reports the manufacturing and the biocompatibility behaviour of two different biocomposite coatings consisting of alumina (Al2O3) and hydroxyapatite (HA) using the high velocity oxygen fuel (HVOF) spraying method which were deposited onto the surface of a commercially pure titanium substrate. The biological properties of the Al2O3-HA materials were evaluated by in vitro studies. The morphology of the coatings before and after their immersing in the simulated body fluid (SBF) solution was characterized by scanning electron microscopy (SEM). The results showed an important germination of the biologic hydroxyapatite crystallite on the surface of both coatings.

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