Mustafa Kaplan - Academia.edu (original) (raw)

Papers by Mustafa Kaplan

Mechanics of Advanced Materials and Structures, 2018

Thermal barrier coatings (TBCs) are commonly applied specifically for aerospace applications in w... more Thermal barrier coatings (TBCs) are commonly applied specifically for aerospace applications in which they are subjected to airborne particles. Therefore, solid particle erosion behavior of all coating layer has been an important phenomenon and erosion behavior of various TBCs has been widely investigated in literature. In the present study, CoNiCrAlY and yttria stabilized zirconia (ZrO 2 + 8% Y 2 O 3) powders were deposited on Inconel 718 nickel based super alloy substrate. Atmospheric plasma spraying technique was applied for the deposition of the metallic bond coat and the ceramic top coats. Erosion tests were carried out under various particle impingement angles with an air jet erosion tester. Afterwards, eroded surfaces of the specimens were investigated with a three-dimensional (3D) optical surface profilometer (noncontact) and scanning electron microscope. The erosion rates, the areal surface roughness values, the 3D surface topographies, and the surface morphology of the specimens were evaluated based on the particle impingement angle to understand the solid particle erosion behavior of the produced coatings. The maximum erosion rates occurred at 60°impingement angle which is an indication of semi-ductile/semi-brittle erosion behavior. Furthermore, the surface roughness values and surface topographies also dramatically varied depending on the impingement angle. Deeper and wider erosion craters formed at 60°impact angle and the erosion craters were visualized by profilometer analysis.

Materiali in tehnologije, 2017

Thermal barrier coatings (TBCs) are commonly applied as a thermal insulation in order to protect ... more Thermal barrier coatings (TBCs) are commonly applied as a thermal insulation in order to protect against environmental influences in the components of high-temperature gas turbines and jet engines. Gas-turbine components are affected by aggressive conditions of the environment during the service, being subjected to failures such as corrosion, thermal shock and oxidation. Plasma-spray technology is used to produce metallic bonds and ceramic top coats as a cost-effective method to prolong the lifetime of TBCs. In the present research, CoNiCrAlY bond-coat and YSZ topcoat powders included in the TBCs were deposited onto Inconel 718 superalloy substrates using atmospheric plasma spraying (APS). The TBCs were exposed to a furnace cycling test at 1150°C and one-hour cycles. The presence of porosity and cracks facilitating the diffusion of oxygen in the top-coating structure led to the formation of thermally grown oxides (TGOs) at the interface. In addition, the most effective factors of failures were the formation and growth of mixed oxides at the bond/top-coat interface and the presence of imperfections. According to the test results, an increasing number of thermal cycles resulted in a decrease in the lifetime of the TBCs related to the sintering of the top coating due to the effect of high temperature. Keywords: thermal barrier coatings (TBCs), thermal cycling, Inconel 718 superalloy, atmospheric plasma spraying (APS), CoNiCrAlY, ytrria-stabilized zirconia (YSZ) Prevleke s toplotno pregrado (angl. TBCs) se obi~ajno uporabljajo kot toplotna izolacija, ki {~iti komponente visoko temperaturnih plinskih turbin ali reaktivnih motorjev. Na komponente plinskih turbin vplivajo agresivni vplivi okolja, katerim so izpostavljene med obratovanjem, zato pride do okvar, kot so: korozija, termi~ni {ok in oksidacija. Tehnologija plazemskega napr{evanja je cenovno ugodna tehnologija za izdelavo kovinskih in kerami~nih prevlek. V~lanku avtorji predstavljajo raziskavo v kateri sta bila na podlago iz zlitine Inconel 718 s tehnologijo plazemskega napr{evanja v zra~ni atmosferi nane{ena vezivna prevleka CoNiCrAlY in prekrivni sloj iz YSZ prahu. Izdelani prevleki sta bili nato izpostavljeni termi~nem utrujanju v pe~i pri 1150°C z ve~imi enournimi cikli. Prisotnost poroznosti in razpok olaj{a difuzijo kisika v zgornjo plast prevleke kar vodi do nastanka termi~no induciranega oksida (TGO) na povr{ini prevleke. Poleg tega sta bila najpomembnej{a dejavnika za nastanek napak tvorba me{anih oksidov na meji med vezno in vrhno plastjo ter prisotnost drugih nepravilnosti. Rezultati preizkusov so pokazali, da pove~anje {tevila termi~nih ciklov zmanj{uje dobo trajanja TBC prevlek, zaradi sintranja zgornje plasti pri povi{anih temperaturah. Klju~ne besede: prevleke s toplotno pregrado, toplotni (termi~ni) cikel, superzlitina Inconel 718, plazemsko napr{evanje, CoNiCrAlY, cirkon stabiliziran z itrijem

It is emerging in many industrial such as defense, aerospace, automotive, energy, marine, and fie... more It is emerging in many industrial such as defense, aerospace, automotive, energy, marine, and fields ships in the direction of reducing the life span of components affecting conditions of use during the solid particle erosion (SPE) induced damage. Solid particle erosion, shows that the formation under the influence of varying different parameters depending on the characteristics of the abrasive particles and abraded surface. Because of this reason, materials of design and manufacturing stages, are taken preventive measures to minimize the rate of erosion may occur in the solid particle erosion due to material surface. In this study, by emphasising on the solid particle erosion and affecting parameters of importance on engineering materials are described in detail.

Mechanics of Advanced Materials and Structures, 2018

Thermal barrier coatings (TBCs) are commonly applied specifically for aerospace applications in w... more Thermal barrier coatings (TBCs) are commonly applied specifically for aerospace applications in which they are subjected to airborne particles. Therefore, solid particle erosion behavior of all coating layer has been an important phenomenon and erosion behavior of various TBCs has been widely investigated in literature. In the present study, CoNiCrAlY and yttria stabilized zirconia (ZrO 2 + 8% Y 2 O 3) powders were deposited on Inconel 718 nickel based super alloy substrate. Atmospheric plasma spraying technique was applied for the deposition of the metallic bond coat and the ceramic top coats. Erosion tests were carried out under various particle impingement angles with an air jet erosion tester. Afterwards, eroded surfaces of the specimens were investigated with a three-dimensional (3D) optical surface profilometer (noncontact) and scanning electron microscope. The erosion rates, the areal surface roughness values, the 3D surface topographies, and the surface morphology of the specimens were evaluated based on the particle impingement angle to understand the solid particle erosion behavior of the produced coatings. The maximum erosion rates occurred at 60°impingement angle which is an indication of semi-ductile/semi-brittle erosion behavior. Furthermore, the surface roughness values and surface topographies also dramatically varied depending on the impingement angle. Deeper and wider erosion craters formed at 60°impact angle and the erosion craters were visualized by profilometer analysis.

Materiali in tehnologije, 2017

Thermal barrier coatings (TBCs) are commonly applied as a thermal insulation in order to protect ... more Thermal barrier coatings (TBCs) are commonly applied as a thermal insulation in order to protect against environmental influences in the components of high-temperature gas turbines and jet engines. Gas-turbine components are affected by aggressive conditions of the environment during the service, being subjected to failures such as corrosion, thermal shock and oxidation. Plasma-spray technology is used to produce metallic bonds and ceramic top coats as a cost-effective method to prolong the lifetime of TBCs. In the present research, CoNiCrAlY bond-coat and YSZ topcoat powders included in the TBCs were deposited onto Inconel 718 superalloy substrates using atmospheric plasma spraying (APS). The TBCs were exposed to a furnace cycling test at 1150°C and one-hour cycles. The presence of porosity and cracks facilitating the diffusion of oxygen in the top-coating structure led to the formation of thermally grown oxides (TGOs) at the interface. In addition, the most effective factors of failures were the formation and growth of mixed oxides at the bond/top-coat interface and the presence of imperfections. According to the test results, an increasing number of thermal cycles resulted in a decrease in the lifetime of the TBCs related to the sintering of the top coating due to the effect of high temperature. Keywords: thermal barrier coatings (TBCs), thermal cycling, Inconel 718 superalloy, atmospheric plasma spraying (APS), CoNiCrAlY, ytrria-stabilized zirconia (YSZ) Prevleke s toplotno pregrado (angl. TBCs) se obi~ajno uporabljajo kot toplotna izolacija, ki {~iti komponente visoko temperaturnih plinskih turbin ali reaktivnih motorjev. Na komponente plinskih turbin vplivajo agresivni vplivi okolja, katerim so izpostavljene med obratovanjem, zato pride do okvar, kot so: korozija, termi~ni {ok in oksidacija. Tehnologija plazemskega napr{evanja je cenovno ugodna tehnologija za izdelavo kovinskih in kerami~nih prevlek. V~lanku avtorji predstavljajo raziskavo v kateri sta bila na podlago iz zlitine Inconel 718 s tehnologijo plazemskega napr{evanja v zra~ni atmosferi nane{ena vezivna prevleka CoNiCrAlY in prekrivni sloj iz YSZ prahu. Izdelani prevleki sta bili nato izpostavljeni termi~nem utrujanju v pe~i pri 1150°C z ve~imi enournimi cikli. Prisotnost poroznosti in razpok olaj{a difuzijo kisika v zgornjo plast prevleke kar vodi do nastanka termi~no induciranega oksida (TGO) na povr{ini prevleke. Poleg tega sta bila najpomembnej{a dejavnika za nastanek napak tvorba me{anih oksidov na meji med vezno in vrhno plastjo ter prisotnost drugih nepravilnosti. Rezultati preizkusov so pokazali, da pove~anje {tevila termi~nih ciklov zmanj{uje dobo trajanja TBC prevlek, zaradi sintranja zgornje plasti pri povi{anih temperaturah. Klju~ne besede: prevleke s toplotno pregrado, toplotni (termi~ni) cikel, superzlitina Inconel 718, plazemsko napr{evanje, CoNiCrAlY, cirkon stabiliziran z itrijem

It is emerging in many industrial such as defense, aerospace, automotive, energy, marine, and fie... more It is emerging in many industrial such as defense, aerospace, automotive, energy, marine, and fields ships in the direction of reducing the life span of components affecting conditions of use during the solid particle erosion (SPE) induced damage. Solid particle erosion, shows that the formation under the influence of varying different parameters depending on the characteristics of the abrasive particles and abraded surface. Because of this reason, materials of design and manufacturing stages, are taken preventive measures to minimize the rate of erosion may occur in the solid particle erosion due to material surface. In this study, by emphasising on the solid particle erosion and affecting parameters of importance on engineering materials are described in detail.