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Öğe Determination of valence electronic structure of Ni in Ni-B alloy coatings using K?-to-K? X-ray intensity ratios(Pergamon-Elsevier Science Ltd, 2019) Cengiz, Erhan; Koksal, Oguz Kagan; Apaydin, Gokhan; Karahan, Ismail Hakki; Unal, ErsinIn this study, K-beta-to-K-alpha X-ray intensity ratios of Ni in Ni-B alloy coatings were investigated. These samples were excited by 59.5 keV gamma-rays from a Am-241 annular radioactive source. K X-rays emitted by the samples were counted using an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The K-beta-to-K-alpha X-ray intensity ratios of Ni-B alloys are compared with pure Ni and each other. Deviations between the results were explained by the change in valence electronic structures of Ni in Ni-B alloy coatings.Öğe Effect of Citrate-Based Bath pH on Properties of Electrodeposited Cu-Zn Coating on an Aluminum Substrate(Springer, 2024) Ozdemir, Rasim; Unal, Ersin; Karahan, IsmaIl HakkiIn this study, Cu-Zn alloys were deposited in citrate-based electrolytes on aluminum substrate by electrodeposition method. The effect of bath pH variation on the properties of the obtained Cu-Zn alloy coatings was investigated. The electrochemical behavior of the citrate-based baths and the crystalline structure, surface morphology and elemental content, electrical resistivity and thermal behavior of the alloy coatings were analyzed. According to the results of cyclic voltammetry (CV) analysis, increasing bath pH caused a negative shift in the cathodic deposition potential. In addition, the anodic dissolution peaks first shifted to the positive side with increasing pH and then shifted back to the negative direction. According to the results of XRD analysis, the phase structure of Cu-Zn alloys generally consists of alpha and beta ' phases, but according to differential scanning calorimeter (DSC) analysis, it is possible that there is a gamma phase in the structure in addition to these phases. In addition, pH increase (4.5 to 6.5) caused a relative increase in crystal grain size (similar to 14 to similar to 25 nm). The Zn content of Cu-Zn coatings first increased (similar to pct 15 to similar to pct 55) with pH increase, then followed a horizontal trend (similar to pct 55 to similar to pct 59) with further pH increase and then exhibited a slight decreasing trend (similar to pct 59 to similar to pct 52). The pH increase significantly affected the surface morphology of the coatings and denser coatings were obtained with increasing pH. While the electrical resistivity of Cu-Zn coatings first increased (0.0408 to 0.0696 mu Omega cm for 297 K) with increasing pH, it tended to decrease (0.0696 to 0.0479 mu Omega cm for 297 K) again at higher pH values. In addition, the electrical resistivity of the coatings increased with increasing measurement temperature. According to DSC analysis of the coatings, endothermic peaks were obtained, possibly representing the transformation from gamma to beta ' phase. [GRAPHICS] . (c) The Author(s) 2024Öğe Effect of trimethylamine borane (TMAB) bath concentration on electrodeposited Ni-B/TiC nanocomposite coatings(Elsevier Sci Ltd, 2023) Unal, Ersin; Yasar, Abdulkadir; Karahan, Ismail HakkiIn this study, stainless steel material was coated with Ni-B alloy-based, TiC particle reinforced composite film using electrochemical deposition method. The properties of the obtained Ni-B/TiC nanocomposite coatings were investigated in terms of the effect of trimethylamine borane (TMAB) bath concentration, which is a boron source. In addition, the data of pure Ni, Ni-B alloy and stainless steel are presented together for comparison. According to the cyclic voltammogram (CV) analysis, it is seen that TMAB contributes to increasing the deposition rate. In the crystal structure analysis, the effect of TMAB was weaker at low TiC bath concentrations, while the effect of TMAB was more dominant at high TiC bath contents. The crystal grain size values of nanocomposite coatings vary between 5.8 and 16.8 nm, and these values decrease up to 86% when compared to the crystal grain size of the pure Ni coating. Although the increase in TMAB initially causes an increase in the microhardness of nanocomposite coatings, when the TMAB value was further increased, it was observed that the microhardness decreased even more compared to the previous initial value. The highest hardness value was obtained in the sample produced at 5 g/l TiC and 6 g/l TMAB bath contents, and this value was 817 HV. Compared to this value, it was observed that the hardness of pure Ni was 65% lower. It was observed that TMAB did not have significant effect on the coating morphology, but the increase in TMAB caused an increase B content and a decrease in the TiC content in the nanocomposite coating. Furthermore, it was revealed that the increase in TMAB bath concentration caused an improvement on corrosion resistance. The corrosion current of the composite sample with 9 g/l TMAB concentration, which showed the best corrosion performance, decreased by 85% compared to pure nickel.Öğe Estimation of microhardness and crystal grain size values of electrodeposited Ni-B/TiC nanocomposite coatings by artificial neural networks (ANN) method(Elsevier Science Sa, 2023) Unal, Ersin; Yasar, Abdulkadir; Karahan, Ismail HakkiIn this study, composite coatings with Ni-B alloy main structure reinforced with TiC nanoparticles were coated on a stainless steel substrate by electrodeposition method. The microhardness and crystal structures of the produced nanocomposite films were examined and the relations between the obtained results and the production parameters were discussed in detail. In addition, the surface and section morphologies of the coatings were analyzed by SEM and EDS. Furthermore the complex relationship between the experimentally obtained microhardness, crystal grain size values and the production parameters was modeled by artificial neural networks (ANN) method. According to the hardness results, nanocomposite coatings microhardness values varied between about 470 HV and 820 HV. In XRD examinations, the crystal grain size values of nanocomposite coatings were found ranging from 6.6 nm to 17.4 nm. From the morphology results, it is understood that the surface structure and coating thicknesses are remarkably affected by the production parameters. Considering the EDS results, it was observed that the alloying with boron and the TiC reinforcement were successfully applied in nanocomposite coatings. With respect to the results obtained with ANN, the best results were obtained in the model with 10 neurons in the hidden layer and the highest error value of 2.02% was achieved for microhardness values. For the crystal grain size, the most successful results were acquired in the model with 12 neurons and the highest error value was obtained as 3.397%.Öğe Investigation of the Properties of Ni-B/TiC Nanocomposite Coatings Produced at Different Particle Concentrations by Electrodeposition(Springer, 2023) Unal, Ersin; Yasar, Abdulkadir; Karahan, Ismail HakkiIn this experimental work, Ni-B/TiC nanocomposite coatings were deposited on a stainless steel substrate by conventional electrodeposition method and their features such as hardness, crystalline structure, corrosion and wear behavior were investigated. Furthermore, the same method was carried out in order to produce pure Ni and Ni-B alloy coatings and their properties were analyzed for comparison purposes. It was observed that nanocomposite coatings had much lower crystal grain size than pure Ni and slightly higher crystal grain size than Ni-B alloy. As a result of SEM analysis, it was determined that both B element and TiC particles were homogeneously deposited into the main structure, and the surface morphology was also affected by these components. According to the microhardness results, it was noted that the nanocomposite coating hardness with the highest hardness value increased by 160 pct compared to the pure Ni and 90 pct more than the Ni-B alloy. In the corrosion analysis, the corrosion resistance of nanocomposite coatings with TiC reinforcement improved significantly, and it was determined that the sample with 12 g/l TiC bath concentration performed 371 pct better than pure Ni and 440 pct better than Ni-B alloy in terms of corrosion current. Moreover, it was determined that the wear performance of nanocomposite coatings improved with increasing hardness and there was a 90 pct reduction in wear volume loss when compared to pure Ni.Öğe A review of electrodeposited composite coatings with Ni-B alloy matrix(Iop Publishing Ltd, 2019) Unal, Ersin; Yasar, Abdulkadir; Karahan, Ismail HakkiCoating processes are of great importance for protecting the materials used in the industry from the damaging effects of external environments and mechanical forces. There are a wide variety of coating methods, but the electrochemical deposition method within them is one step ahead because of its low cost, easy manufacturability and rapidity. Ni-B coatings have been produced for many years by the electroless deposition method, but electrodeposited Ni-B coatings are a relatively new research topic and attract much attention in recent years. Due to its superior properties Ni-B alloy coatings are successfully used in many industries such as aerospace, automotive, petrochemical, chemical and electronics. Works on reinforcing Ni-B alloys with second phase particles to increase these properties to a better level has been increasing rapidly in recent years. Ni-B alloy and composite coatings were investigated in this study. Furthermore, the bath components, production parameters, contents and properties of Ni-B alloy matrix composite coatings were presented comparatively. It was revealed that reinforcing the Ni-B alloy matrix with ceramic particles affected properties such as crystal structure, morphology, hardness, corrosion and abrasion resistance very seriously.
