Sukru Taktak - Academia.edu (original) (raw)

Papers by Sukru Taktak

Surface and Coatings Technology, 2006

Borided steels are known to exhibit excellent wear resistance at room temperature. However, the s... more Borided steels are known to exhibit excellent wear resistance at room temperature. However, the sliding wear behaviour of borided steels at high temperatures is not known. In the present study, AISI 440C and 52100 bearing steels which are extensively used in ...

Materials & Design, 2007

In the present study, mechanical properties of borides formed on AISI H13 hot work tool and AISI ... more In the present study, mechanical properties of borides formed on AISI H13 hot work tool and AISI 304 stainless steels have been investigated. Both steels have high chromium content and have a widespread use in the engineering application. Boriding treatment was carried out in slurry salt bath consisting of borax, boric acid, and ferrosilicon at temperature range of 800-950°C for 3, 5, and 7 h. X-ray diffraction analysis of boride layers on the surface of steels revealed various peaks of FeB, Fe 2 B, CrB, and Ni 3 B. Metallographic studies showed that the boride layer has a flat and smooth morphology in the 304 steel while H13 steel was a ragged morphology. The characterization of the boride layer is also carried out by means of the micro-hardness, surface roughness, adhesion, and fracture toughness studies.

Journal of The Balkan Tribological Association, 2014

In the present study, AISI 8620, 52100 and 440C steels were plasma paste boronized (PPB) by using... more In the present study, AISI 8620, 52100 and 440C steels were plasma paste boronized (PPB) by using 100% borax paste. PPB process was carried out in a dc plasma system at temperature of 700 and 800°C for 3 and 5 h in a gas mixture of 70%H2-30%Ar under a constant pressure of 4 mbar. Wear tests of the bearing steels were performed using a ball-on-disc test device. The applied loads on the ball were 5 and 20 N and the sliding time was 60 min for each test. Wear tests were carried out in the unlubricated and lubrication conditions at room temperature in air. Wear volume of the disc specimen was determined from the cross-sectional area of the wear track, obtained perpendicularly to the sliding direction. Worn surfaces of the samples were PPB characterized by scanning electron microscopy and the results were compared with those obtained for plasma paste boronized specimens.

The boriding treatment is the suitable process which caused an increase in surface hardness and w... more The boriding treatment is the suitable process which caused an increase in surface hardness and wear resistance of nickel and its alloys. However, the phase composition of boride layers strongly influences on layer properties—especially hardness and brittleness. The method of plasma paste boriding was used in this study to produce the hard boride layers on nickel-based alloys: Ni201, Inconel 600, and Nimonic 80A. This process was carried out at 800 °C (1073 K) for 3 h. The chemical composition of substrate material was the reason for producing of layers which were characterized by different thickness: 55 μm for Ni201, 42 μm for Inconel 600, 35 μm for Nimonic 80A. The lowest hardness (1000–1400 HV) and the highest fracture toughness (up to 2.6915 MPa m1/2) were measured for layer produced on Ni201. In this specimen, only nickel borides were detected. However, due to high content of chromium, in case of Inconel 600-alloy and Nimonic 80A-alloy, the higher hardness (in the range of 1000...

Surface and Coatings Technology, 2019

Plasma paste boridingat temperature of 800ºC (1073K) for 3 h was applied in order to produce hard... more Plasma paste boridingat temperature of 800ºC (1073K) for 3 h was applied in order to produce hard ceramic phases on the surface of Ni-based alloys with various chromium concentrations. The microstructure of boride layerdepended on the chemical composition of substrate material.The increase in chromium concentration was the reason for reducing the average thickness ofthe boride layers. Hence, the average thicknesses were as follows: 54.24±3.07 µm for Nickel 201-alloy, 44.41±2.24μm for Inconel ® 600-alloy, 41.31±1.56μm for Nimonic ® 80A-alloy. The chemical and phase composition of the investigated layers strongly influenced their hardness (HV IT), Young's modulus (E IT) and fracture toughness (K c). The boride layer, produced on Nickel 201-alloy, was characterized by lowest average hardness of 17.97±1.59GPa and Young's modulus of 217.89±20.72GPa. The highest values of H IT andE IT (22.96±4.30GPa and 291.95±25.64GPa, respectively)were obtained for boride layer on Nimonic ® 80A-alloyin which the highest chromium concentration occurred. It was also confirmed that the increase in chromium concentration in substrate material strongly influenced the fracture toughness of the produced layers. The plasma-paste borided layer, in which only nickel borides were identified, was characterized by the highest average fracture toughness (K c) of 1.477±0.86 MPa•m 1/2. Whereas, the boride layer on Nimonic ® 80A-alloy (Cr content of 19.52 wt.%) was characterized by about tree time lower fracture toughness (K c =0.534±0.44 MPa•m 1/2).

International Journal of Materials Engineering Innovation, 2018

In this study, the pure titanium (Cp-Ti) was successfully borided in molten salts bath of (70 wt.... more In this study, the pure titanium (Cp-Ti) was successfully borided in molten salts bath of (70 wt.% borax and 30 wt.% B 4 C) at the three temperatures (800,900 and 1,000°C) for time treatment ranging from 3 to 12 h. SEM observations showed the formation of the TiB 2 layers followed by TiB whiskers penetrating into the matrix. The XRD studies also confirmed the presence of TiB 2 top-layer and TiB whiskers sub-layer on the surfaces of hardened materials by boriding. The kinetics of formation of entire boride layer (TiB 2 + TiB) was analysed. As a main result, the values of activation energies for boron diffusion in Cp-Ti were estimated by using two different approaches (classical parabolic growth law and integral method) as equal to 130.6 and 130.77 kJmol-1 , respectively. These two values of energy were finally compared to the results available in the literature.

Transactions of the Indian Institute of Metals, 2016

In this study, the AISI 440C steel was plasma paste borided in a gas mixture of 70 %H 2-30 %Ar us... more In this study, the AISI 440C steel was plasma paste borided in a gas mixture of 70 %H 2-30 %Ar using borax paste as a boron source. This thermochemical treatment was carried out at three temperatures of 700, 750 and 800°C for 3, 5 and 7 h. The morphology of the formed boride layers was studied by scanning electron microscope. An identification of iron borides was performed using an X-ray microanalyzer, equipped with energy dispersive X-ray spectroscopy. The phases present in the boride layer were identified by means of X-ray diffraction analysis. In addition, the glow discharge optical spectroscopy analysis was performed in order to determine the concentration profiles of elements. The wear resistance of plasma paste borided AISI 440 C steel (at 800°C for 3 h) was also investigated. As a result, the value of boron activation energy for the AISI 440C steel was found to be equal to 134.62 kJ mol-1 on the basis of our experimental results. Finally, this value of boron activation energy was compared to the literature data.

Transactions of the Indian Institute of Metals, 2017

The AISI 316 steel was treated by the plasma paste boriding by using a gas mixture of 70%H 2-30%A... more The AISI 316 steel was treated by the plasma paste boriding by using a gas mixture of 70%H 2-30%Ar with a boron source of 100% B 2 O 3 in the temperature range of 700-800°C for 3, 5 and 7 h. The boride layers formed on the samples were observed by scanning electron microscope. The iron borides were also identified by the use of an X-ray microanalyzer, equipped with energy dispersive X-ray spectroscopy. The XRD analysis was carried out to identify the iron and metallic borides present inside the boride layer. Based on the kinetic data, the value of boron activation energy for the AISI 316 steel was estimated as 118.12 kJ mol-1 and compared with the data available in the literature. A regression model based on ANOVA analysis was used to predict the boride layers' thicknesses depending on the boriding parameters: the treatment time and the boriding temperature. A good correspondence was obtained between the experimental values and those predicted by the regression model. Furthermore, the wear behavior of the sample borided at 750°C for 5 h was investigated. The significant increase in wear resistance of plasma borided layer was observed in comparison with the untreated AISI 316 steel. The nanomechanical properties of the sample, plasma paste borided at 700°C for 7 h, were examined using the nanoindenter with a Vickers diamond tip. The load-displacement curves, as well as, Young's moduli and hardness were shown for the selected measurements. The obtained results depended on the phase composition of the tested area.

Surface and Coatings Technology, 2015

In the present study, Cp-Ti and Ti6Al4V alloy were successfully plasma paste borided using borax ... more In the present study, Cp-Ti and Ti6Al4V alloy were successfully plasma paste borided using borax paste. The process was carried out in a dc plasma system at a temperature of 973, 1023 and 1073 K for 3, 5 and 7 h in a gas mixture of 70% H 2-30% Ar under working pressure of 5 mbar. The properties of the boride layers were evaluated by scanning electron microscopy, X-ray diffraction and the micro-Knoop hardness tester. Growth kinetics of the titanium boride layers on the Cp-Ti and Ti6Al4V alloy were obtained by analyzing the experimental results and parameters including the thickness of boride layer, correspondent diffusion temperature and holding time. The presence of both TiB 2 top-layer and TiB whisker sub-layer was confirmed by the X-ray diffraction and scanning electron microscopy techniques. The formation rate of the dual titanium boride layers was found to have a parabolic character at all applied process temperatures. The surface hardness of TiB 2 layer ranged between 2077 and 2373 HK 0.025. The activation energies of boron in Cp-Ti and Ti6Al4V alloy were calculated as 93.61 and 99.79 kJ.mol-1 , respectively depending on the temperature and layer thickness.

Journal of Adhesion Science and Technology, 2015

In this study, adhesion properties of boride layers formed on the surface of AISI 52100, AISI 514... more In this study, adhesion properties of boride layers formed on the surface of AISI 52100, AISI 5140, AISI 440C, AISI 420 and AISI 304 steels were investigated. Boronizing treatment was carried out in Ekabor-II powders at the temperatures of 850 and 950 °C for 4 h. The properties of boride layers were evaluated by optical microscopy, SEM, X-ray diffraction and micro-Vickers hardness tester. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layers. Test result showed that adhesion of boride layers depended on the dual-phase structure. The stresses at the FeB/Fe2B interphase caused delamination failure and poor interphase adhesion with increase in the depth of hard and brittle FeB-based layer.

Applied Surface Science, 2017

 Formation rates of the Ti boride layers have parabolic character at all temperatures.  Boron d... more  Formation rates of the Ti boride layers have parabolic character at all temperatures.  Boron diffusivities were estimated using a diffusion model including incubation times  Activation energies of boron in TiB2 and TiB were 136 and 63 kJ/mol respectively.

Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, 2012

Bu calismada endustride yatak celigi olarak kullanilan 21NiCrMo2 celigi agirlikca %100 B2O3, %70 ... more Bu calismada endustride yatak celigi olarak kullanilan 21NiCrMo2 celigi agirlikca %100 B2O3, %70 B2O3 +%30 SiC, %70 B2O3 +% 30 B4C, % 30 B2O3 + %70 SiC, %30 B2O3 + %70 B4C pasta karisimlari kullanilarakplazma pasta borlanmistir. Plazma pasta borlama (PPB) islemi, 700, 750 ve 800 °C de 2, 5 ve 7 saat suresince%70H2 – %30Ar gaz karisiminda 10 mbar basinc altinda yapilmistir. Ayni celik ticari Ekabor II tozuyla aynisicaklik (700, 750, 800°C) ve surelerde (2, 5, 7 saat) elektrik resistansli firinda kutu borlama islemine tabitutulmustur. Elde edilen borur tabakalarinin, SEM, EDX, X-isini difraksiyon, mikrosertlik ve mikroyapiozellikleri incelenmistir. X-isini difraktometrik analizi sonucunda celigin yuzeyinde FeB ve Fe2B tabakalarininolustugu gorulmustur. B2O3 pasta karisimlari kullanarak plazma ortaminda daha dusuk sicaklik ve surelerde kutuborlama yontemine gore daha kalin borur tabakalari elde edilmistir.

Materiali in tehnologije, 2016

In this work, AISI 316 steel was plasma-paste borided in a gas mixture of 70 % H2-30 % Ar using a... more In this work, AISI 316 steel was plasma-paste borided in a gas mixture of 70 % H2-30 % Ar using a mixture of 30 % SiC + 70 % B2O3 as a boron source. The samples were treated at temperatures of (700, 750 and 800)°C for (3, 5 and 7) h. The morphology of the formed boride layers was examined by light microscope and scanning electron microscope coupled to an EDS analyser. The borides present in the boride layer were identified by means of XRD analysis. The boron-activation energy for the AISI 316 steel was found to be equal to 250.8 kJ mol-1. This value for the energy was compared to the literature data. A regression model based on a full factorial design was used to estimate the boride layers' thicknesses as a function of the boriding parameters: time and temperature. A comparison was made between the values of the boride layers' thicknesses estimated from the regression model with those given by an empirical relation. In addition, an iso-thickness diagram was plotted to predict the boride-layer thickness as a function of the processing parameters. This iso-thickness diagram can serve as a simple tool to select the optimum values for the boride layers' thicknesses for a practical utilisation in industry for this kind of steel.

The Physics of Metals and Metallography, 2015

Silver containing amorphous carbon films were deposited on Si wafer using a hybrid deposition pro... more Silver containing amorphous carbon films were deposited on Si wafer using a hybrid deposition process combining d.c. magnetron sputtering and PECVD. The concentration of Ag in the films was varied from 1.3 to 8.3 at % by changing d.c. magnetron current of Ag target. The influence of incorporated Ag in the a C:H on the atomic bond structure of the films were investigated by XPS, FTIR, Raman, and HRTEM methods of analysis. The XPS, FTIR, and Raman studies demonstrated that as the silver concentration increased in the a C:H, sp2 bonding content increased and a C:H films changed to more graphitic structure. The high resolution TEM cross sectional studies revealed that crystalline Ag particles formed with a size in the range of 2-4 nm throughout an amorphous a C:H matrix.

Protection of Metals and Physical Chemistry of Surfaces, 2013

In the present study, AISI 8620 steel was plasma paste boronized by using various borax paste mix... more In the present study, AISI 8620 steel was plasma paste boronized by using various borax paste mix tures. The plasma paste boronizing process was carried out in a dc plasma system at a temperature of 973, 1023 and 1073 K for 2, 5 and 7 h respectively in a gas mixture of 70% H 2-30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X ray diffraction, the micro Vickers hardness tester and the growth kinetics of the boride layers. The thickness of the boride layers varied from 14 to 91 μm depending on the boronizing time and temperature. X ray diffraction analysis of boride layers on the surface of the steel revealed the formation of FeB and Fe 2 B phases. Depending on the temperature and layer thickness, the activation energies of boron in steel were found to be 99.773 kJ/mol for 100% borax paste.

Journal of the Balkan Tribological Association