SEARCH RESULT

Thermal barrier coatings (TBCs) are used in high temperature applications to extend lifetime of metallic components. Especially, aircraft components such as turbine blades or vanes coated with TBCs [1]. In operating conditions, these components exposed to oxidation and corrosion. Thus, TBCs have limited lifetime in high temperature conditions. To determine the lifetime of TBCs, there are a few methods such as furnace thermal cyclic test, burner-rig test or jet engine thermal shock test [2]. Under high temperature conditions, oxygen diffuses from top coat to bond coat and, thermally grown oxide (TGO) layer form at the interface. This layer leads to high stress due to thermal expansion mismatch between bond and top coat. In figure 1, there is an example image taken at the end of furnace cyclic test for a tbc system. For this reason, TBCs are usually spalled from the TGO layer [3]. In this study, thermal cycling tests will be explained with experimental data.

International Symposium on Light Alloys and Composite Materials
UHAKS

Kadir Mert DOLEKER Yasin OZGURLUK Hayrettin Ahlatçı Abdullah Cahit KARAOGLANLI

Thermal barrier coatings (TBCs) are generally used as a protective coating in gas turbine engine components in aerospace and aircraft industry [1]. Especially, TBCs applications used critical region parts exposed to high temperatures such as oxidation, hot-corrosion, thermal shock failures and CMAS (calcia–magnesia–alumina–silica) attack [2]. Volcanic ash degradation of TBC is a serious problem for many high temperature applications in aggressive environment such as turbine blades and vanes in gas turbines [3]. Impurities arising from the desert and volcanic environment dusts such as calcia–magnesia–alumina–silica (CMAS) formations cause degradation during the service conditions [4]. In this study, the effect of volcanic ash based failures were investigated and discussed in TBC systems.

International Symposium on Light Alloys and Composite Materials
UHAKS

Yasin OZGURLUK Kadir Mert DOLEKER Hayrettin Ahlatçı Abdullah Cahit KARAOGLANLI

The milling of carbon fiber reinforced polymers (CFRP) is a challenging process due to the non-homogeneous, anisotropic structure and extreme hardness of this type of material. Tool wear occurring during the machining process and the resulting failure mechanisms including delamination, matrix and fiber breakage have severely adverse effects on surface quality of machined products. Since deterioration of machined surface quality may impair the strength of components, particular importance is attached to this situation especially in aviation industry. As a failure mechanism arising from the machining of the materials, this situation may result in timeless damages on critical components, such that, almost 60 % milled CFRP components are discarded due to delamination-related damages. In this context, investigation of the failure mechanisms resulting from delamination and delamination-related situations arising during the milling of CFRP composites was aimed in the present research.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

Dervis Ozkan Mustafa Sabri Gök Hasan GÖKKAYA Abdullah Cahit KARAOGLANLI

In the present research on milling of carbon fiber reinforced polymer (CFRPs) composites widely used in aviation industry, the effects of different cutting speeds and feed rates on the surface roughness was investigated using tungsten carbidecobalt based (WC-Co) carbide cutting tools. A CFRP composite with 6 mm thickness and 24 layers was used as the work-piece. The tests were performed on a CNC vertical processing center with 100, 200 and 300 m/min cutting speeds, 0.05-0.15 and 0.25 mm/tooth feed rates and 1 mm constant cutting width under dry conditions. Following the tests, the surface roughness of the work-piece was investigated. 5.7 µm surface roughness was obtained with 100 m/min cutting speed and 0.25 mm/tooth feed rate.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

Dervis Ozkan Mustafa Sabri Gök Hasan GÖKKAYA Abdullah Cahit KARAOGLANLI

As a protective coating method initially developed for space and aviation industry thermal spray coating techniques have been widely used in several fields. Among a vast number of thermal spray coating techniques, Atmospheric Plasma Spraying (APS) and High Velocity Oxygen Fuel (HVOF) techniques are widely applied against harsh conditions such as wear, oxidation and corrosion due to their high applicability and cost efficiency. In the present research NiCr coating was deposited on Inconel 718 substrate materials using plasma spray and HVOF methods, and the coated specimens were subjected to dry sliding wear tests under 3, 5, 7 and 10N loads at 0,08 m/s sliding speed using a pin-on-disc tribometer. Characterization of the coated specimens was performed before and after the wear tests using conventional characterization techniques. According to the wear loss and coefficient of friction values obtained after the performed tests, the coatings deposited with HVOF technique exhibited a higher wear performance as compared to those deposited with APS technique.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

Mecit Oge Fettullah Yildiz S. Parlakyigit Mustafa Sabri Gök Abdullah Cahit KARAOGLANLI