Developing Empirical Relationships to Predict Porosity and Microhardness of Atmospheric Plasma-Sprayed Alumina Coatings on AZ31B Magnesium Alloy

2015 ◽  
Vol 15 (2) ◽  
pp. 169-181 ◽  
Author(s):  
D. Thirumalaikumarasamy ◽  
K. Shanmugam ◽  
V. Balasubramanian
Keyword(s):  
Barrier Properties ◽  
Input Power ◽  
Atmospheric Plasma ◽  
Operational Parameters ◽  
Empirical Relationships ◽  
Alumina Coatings ◽  
Experimental Conditions ◽  
Wear And Corrosion Resistance ◽  
Two Parameters ◽  
Plasma Sprayed

AbstractPlasma-sprayed alumina coatings find wide-ranging applications by virtue of their inherent wear and corrosion resistance and attractive dielectric and diffusion barrier properties. In this work, empirical relationships were developed to predict the porosity and microhardness of alumina coatings by incorporating independently controllable atmospheric plasma-sprayed operational parameters (input power, stand-off distance and powder feed rate) using response surface methodology (RSM). A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the stand-off distance appeared to be the most significant two parameters affecting the responses among the three investigated process parameters. A linear regression relationship was also established between porosity and microhardness of the alumina coatings.

The Role of Different Atmospheric Plasma Spray Parameters on Microstructure of Abradable AlSi-Polyester Coatings

2017 ◽  
Vol 270 ◽  
pp. 224-229
Author(s):  
David Jech ◽  
Ladislav Čelko ◽  
Pavel Komarov ◽  
Jindřich Ziegelheim ◽  
Zdeněk Česánek ◽  
...  
Keyword(s):  
Deposition Efficiency ◽  
Atmospheric Plasma ◽  
Spray Parameters ◽  
Technological Parameters ◽  
Coating Microstructure ◽  
Two Parameters ◽  
Plasma Sprayed ◽  
Abradable Coatings ◽  
And Control

One of the approaches to increase the thermic efficiency of aerospace engines is the application of abradable coatings enabling minimization and control of the clearance between the stator and the rotating blades tips. The main purpose of this contribution is to define the role of different technological parameters utilized for atmospheric plasma spraying of AlSi-polyester coating on its resulting microstructure. Deposition of abradable coatings on the real engine parts is mostly dependent on spraying stand-off distance and on spraying angle. These two parameters influence not only the coating microstructure but also the deposition efficiency itself, which is directly connected with economical aspects of the coating production. The set of experimental samples with atmospheric plasma sprayed Ni-based bond coat and two in chemical composition same initial powders delivered from different powder manufacturers were used to spray thick AlSi-polymer top coats with different spraying stand-off distances and angles. Subsequently some of the samples were also heat treated to burn-out the polymer phase from the coating microstructure. The Rockwell HR15Y hardness was measured on all samples and the microstructure and coating thickness were evaluated by means of light microscopy and image analysis methods.

Microstructural and Corrosion Properties of Atmospheric Plasma Sprayed Alumina Coatings on AZ31B Magnesium Alloy Under Sodium Chloride Environment

2016 ◽  
Vol 16 (2) ◽  
pp. 89-102
Author(s):  
D. Thirumalai kumarasamy ◽  
K. Shanmugam ◽  
V. Balasubramanian ◽  
S. Vignesh
Keyword(s):  
Magnesium Alloy ◽  
Immersion Time ◽  
Ph Value ◽  
Chloride Ion ◽  
Atmospheric Plasma ◽  
Ion Concentration ◽  
Design Matrix ◽  
Alumina Coatings ◽  
Az31b Magnesium Alloy ◽  
Plasma Sprayed

AbstractThe corrosion deterioration process of plasma sprayed alumina coatings on AZ31B magnesium alloy was investigated using immersion corrosion test in NaCl solution at different chloride ion concentrations, pH value and immersion time. The experiments were conducted based on a three factor, five level, central composite rotatable design matrix with full replications technique. Response surface methodology was used to develop the relationship. The developed relationship can be effectively used to predict the corrosion rate of plasma sprayed alumina coatings on AZ31B magnesium alloy at 95 % confidence level. The results showed that the corrosion deterioration of alumina coated magnesium alloy in NaCl solutions was significantly influenced by chloride ion concentration and pH value. The alumina coatings were found to be highly susceptible to localized damage, and could not provide an effective corrosion protection to Mg alloy substrate in solutions containing acidic environments (pH3), higher chloride concentrations and immersion time.

scholarly journals Porosity Characterization and Its Effect on Thermal Properties of APS-Sprayed Alumina Coatings

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 601
Author(s):  
Wolfgang Tillmann ◽  
Omar Khalil ◽  
Mohamed Abdulgader
Keyword(s):  
Pore Size ◽  
Thermal Insulation ◽  
Thermal Spraying ◽  
Total Porosity ◽  
Ceramic Coatings ◽  
Atmospheric Plasma ◽  
Powder Size ◽  
Feedstock Powder ◽  
Alumina Coatings ◽  
Plasma Sprayed

In the thermal spraying process, the porosity of ceramic coatings contributes directly to the efficiency of the thermal insulation. The size, shape, and distribution of the pores determine the level of both thermal and sintering resistance. In this work, three different atmospheric plasma sprayed (APS) alumina coatings were fabricated with the same spraying parameters using alumina powders with fine, medium, and coarse particle size. The microstructure of the obtained coatings was analyzed regarding the obtained total porosity, pore size, and pore shape. It was found that it is expedient to divide the pore size range into fine, medium, and large sizes. The shape was characterized with regard to the circularity aspect. In this way, all types of cracks can be considered as oblate pores and were included in the calculation of the total porosity. In the case of using fine feedstock powder, the densest coatings were produced among all coatings, and the fraction of fine pores and cracks are thereby substantially higher. However, the total porosity increases with increasing feedstock powder size. A connection was also made between thermal insulation and porosity fraction which includes fine pores and cracks.

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