Characterization of Microstructure and Properties of Plasma Sprayed Ceramic Coatings on AZ91 Magnesium Alloy

The paper presents the microstructure test results of carbide layers with bond coat obtained on the magnesium alloy with WC/Co – NiCr – AZ91D type thermal spraying method. Layers were sprayed with the APS method on the sandblasted surfaces of approx. 5 mm thick elements manufactured with high pressure die casting (HPDC). The standard process parameters were used for the powders sprayed. The scope of the tests included characteristics of the AZ91D alloy top surface after HPDC process and after sandblasting. The stereometric analysis of surface was performed by using the laser profilometer. The top surface geometric parameters were determined and presented in the form of numbers and topographic maps. Both surfaces were subject to SEM analysis by using the Hitachi S3400N microscope and chemical composition analysis in micro areas (EDX analysis by using the Noran System Six software) to determine presence of impurities and other type of artefacts on the alloy surface before plasma spraying. The alloy surfaces were also subject to detailed tests after spraying process (on lateral micro-sections) to determine the influence of the spraying process on the substrate quality and consequently layer adhesion. Phase composition assessment of the NiCr 80/20 type bond coat and carbide layers WC/10Co and WC/8Co was also performed. Further tests referred to top surface morphology of both carbide layers and chemical composition assessment in micro areas.

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The Numerical Modeling of Thermal Stress Distribution in Thermal Barrier Coatings

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0221 ◽

2017 ◽

Vol 62 (3) ◽

pp. 1433-1437

Author(s):

A. Jasik

Keyword(s):

Thermal Stress ◽

Stress Distribution ◽

Thermal Barrier Coatings ◽

Bond Coat ◽

Thermal Spraying ◽

Ceramic Coatings ◽

Thermal Barrier ◽

Insulation Layer ◽

Barrier Coatings ◽

Thermal Stress Distribution

Abstract The paper presents the results of numerical calculations of temperature and thermal stress distribution in thermal barrier coatings deposited by thermal spraying process on the nickel based superalloy. An assumption was made to apply conventional zirconium oxide modified with yttrium oxide (8YSZ) and apply pyrochlore type material with formula La2Zr2O7. The bond coat was made of NiCoCrAlY. Analysis of the distribution of temperature and stresses in ceramic coatings of different thicknesses was performed in the function of bond-coat thickness and the type of ceramic insulation layer. It was revealed that the thickness of NiCrAlY bond-coat has not significant influence on the stress distribution, but there is relatively strong effect on temperature level. The most important factor influenced on stress distribution in TBC system is related with type and properties of ceramic insulation layer.

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Production of Nanocellulose Crystal Derived from Enset Fiber Using Acid Hydrolysis Coupled with Ultrasonication, Isolation, Statistical Modeling, Optimization, and Characterizations

Journal of Nanomaterials ◽

10.1155/2021/7492532 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Surafel Mustefa Beyan ◽

Temesgen Abeto Amibo ◽

S. Venkatesa Prabhu ◽

Abraham Getahun Ayalew

Keyword(s):

Chemical Composition ◽

Acid Hydrolysis ◽

Sem Analysis ◽

Raw Material ◽

Fiber Bundles ◽

Quadratic Model ◽

Composition Analysis ◽

Bearing Material ◽

Excellent Thermal Stability ◽

Renewable Biomass

Currently, many scholars are looking for renewable biomass sources for the isolation of nanomaterials that have a sustainable property and are ecofriendly. Thus, effectively synthesize and characterization enset fiber nanocellulose using acid hydrolysis with sonication is focus of study. Additionally, process optimization for isolation of nanocellulose (CNCs) from raw enset fiber using RSM-CCD and characterizations of obtained CNCs was explored. The quadratic model was selected, and optimized values for CNCs yield (77.69%) that were acquired to be H2SO4: 51.6 wt. %, reaction temperature: 47°C, and time: 66.5 min. Chemical composition analysis, XRD, FTIR, PSA, SEM, and TGA were used for characterizing CNCs. The particle size distribution of CNCs is 66 nm. It has a crystalline index of 80.91% and excellent thermal stability. FTIR and chemical composition result indicated the reduction and removal of lignin and hemicellulose components that are usually available in the raw enset fibers. The SEM analysis reveals the structure and arrangement of the fiber bundles inside the raw material to nanocellulose. This property shows its endowing as a possibly consistent load-bearing material. This study could be given a noteworthy thought for designing and emerging CNC isolation, optimization, and industrial application.

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Composition analysis and corrosion performance of a Mo–Ce conversion coating on AZ91 magnesium alloy

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2014.06.044 ◽

2014 ◽

Vol 254 ◽

pp. 364-370 ◽

Cited By ~ 24

Author(s):

Songlin Mu ◽

Jun Du ◽

Hui Jiang ◽

Wenfang Li

Keyword(s):

Magnesium Alloy ◽

Conversion Coating ◽

Composition Analysis ◽

Corrosion Performance ◽

Az91 Magnesium Alloy ◽

Az91 Magnesium

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Theory of Particle Composition Analysis During Thermal Spraying

Thermal Spray 2000: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2000p0165 ◽

2000 ◽

Author(s):

J. Wilden ◽

H. Frank

Keyword(s):

Chemical Composition ◽

Boundary Conditions ◽

Particle Temperature ◽

Thermal Spraying ◽

Plasma Temperature ◽

Composition Analysis ◽

Thermal Spray Process ◽

Spray Process ◽

Characteristic Lines ◽

On Line

Abstract The properties of thermally sprayed coatings significantly depend on the alloy composition and the adjusted process parameters. In addition to the powder certificate it may be useful to analyse the chemical composition of the sprayed powder during the spraying process itself. The principle of composition analysis is similar to the chemical analysis in an ICP plasma but the boundary conditions are more complex because the sprayed powder should not be completely evaporated in a thermal spray process. Nevertheless all thermal spraying processes lead to a certain evaporation of the species and to excitation of atomic states. The transition into the ground state occurs under emission of characteristic lines. The intensity of these lines is influenced by the plasma temperature, the particle temperature, the temperature dependent evaporation rate of the alloying elements and the powder feed rate. In consideration of the boundary conditions and the information from a detailed analysis of the emitted spectra the lines can be used to quantify the chemical composition of the sprayed alloys online. The theory of the principle for on-line analysing the chemical composition will be deduced and the first experimental validation will be presented.

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Plasma Spraying of Spray-Dried AI2O3 Powders

Thermal Spray 2000: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc2000p1371 ◽

2000 ◽

Author(s):

G. Bertrand ◽

B. Hansz ◽

F. Tourenne ◽

C. Coddet

Keyword(s):

Chemical Composition ◽

Plasma Spraying ◽

Gas Flow ◽

Raw Materials ◽

Thermal Spraying ◽

Ceramic Coatings ◽

Crystallographic Structure ◽

Ceramic Powders ◽

Spray Process ◽

Spray Dried

Abstract Today, powder particles diameter used for thermal spraying is generally comprised between 5 and 100µm with a preferred range around 40µm for APS applications. Actually, the future trends in plasma spraying are directed to the use of fine or ultrafine powders and the reduction of the steps between raw materials and coatings. So, the present paper investigates the way to use directly spray dried ceramic powders in suppressing the sintering stage. AI2O3 based powders were obtained by the spray drying process. By optimizing the parameters (slurry composition and injection as well as drying characteristics), a narrow grain size distribution was achieved. Chemical composition and shape of synthesized powders were analyzed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). The crystallographic structure was identified by X-ray diffraction (XRD). Demonstration was made that it is possible to obtain coatings using directly spray dried ceramic powders. The plasma spray process parameters (such as current intensity, gas flow rate, powder feed rate and injection mode, cooling stage,...) have to be managed to achieve cohesive coatings. The structure and chemical composition of these coatings were studied. In this way, the direct use of spray dried powders appears as a promising way to realize ceramic coatings.

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Characterization of Ni-P coating prepared via electroless deposition on AZ31 magnesium alloy

Koroze a ochrana materialu ◽

10.1515/kom-2016-0026 ◽

2017 ◽

Vol 61 (1) ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

M. Buchtík ◽

P. Kosár ◽

J. Wasserbauer ◽

P. Doležal

Keyword(s):

Chemical Composition ◽

Magnesium Alloy ◽

Electroless Deposition ◽

Mechanical Characteristics ◽

Chemical Properties ◽

Composition Analysis ◽

Physico Chemical ◽

Chemical Composition Analysis ◽

Scanning Electron

Abstract This work deals with the characterization of Ni–P coating prepared via electroless deposition on wrought AZ31magnesium alloy. For the application of electroless deposition was proposed and optimized a suitable pretreatment process of magnesium alloy surface followed by Ni–P coating in the nickel bath. The chemical composition of Ni–P based coating was characterized using the scanning electron microscope with chemical composition analysis. Next, physico-chemical properties and mechanical characteristics of Ni–P coating were evaluated. The mechanism of corrosion degradation of the coating and the substrate was also studied in this work.

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Analysis of the Metallurgical Bonding between Inconel and NiCrAlY Coatings by HVOF and with CO2 Laser Beam

Materials Science Forum ◽

10.4028/www.scientific.net/msf.869.727 ◽

2016 ◽

Vol 869 ◽

pp. 727-731 ◽

Cited By ~ 1

Author(s):

Ana Claudia Costa Oliveira ◽

G. Donato ◽

R. Magnabosco ◽

Viviane Teleginski ◽

Daniele Cristina Chagas ◽

...

Keyword(s):

Laser Beam ◽

Bond Coat ◽

Turbine Blades ◽

Thermal Spraying ◽

Ceramic Coatings ◽

Particulate Material ◽

Metallic Substrate ◽

Inconel 625 ◽

Metallurgical Bonding ◽

Hvof Thermal Spraying

Coatings are applied on turbine blades’ surfaces to provide protection not only against high temperature but also against aggressive environment. Ceramic coatings are employed to avoid metallic substrate overheating, while at the same time increasing turbine work temperature and performance. A bond coat (BC) base of particulate material based on Ni-Al powders is necessary to assure oxidation protection, a good adhesion and gradual decrease in thermal expansion coefficient between the blades’ metallic substrate and the ceramic top coating. One of the most important parameters of such coatings is the adhesion strength. In this work, a NiCrAlY bond coat was deposited on Inconel 625 substrate employing High-Velocity Oxygen-Fuel (HVOF) thermal spraying technology and CO2 laser beam irradiation to enhance coating–substrate adherence and metallurgical bonding. Microstructural features were examined by optical and scanning electron microscopy (SEM), X-ray diffraction and microhardness analysis. The results indicate that the laser treatment provided an efficient metallurgical bond between the (BC) and Inconel 625 substrate.

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