The purpose of this work was to investigate the coatings made of Cr3 C2 and SiC powder manufactured on AISI 304 stainless steel applied by the plasma transferred arc (PTA) welding process. SiC content in the produced coated layer was varied between 0–100 wt.% and the effect of SiC concentration on the microstructure and hardness of the coating was measured experimentally. SEM analyses revealed that the composite coatings had a homogeneous, nonporous, and crack-free microstructure. Dendrites and interdendrite eutectics formed on the coating layer, subject to the temperature gradient and the solidification ratio. There was a significant increase in the hardness of coating layers with the effect of the γ -(Fe,Ni), Cr7 C3, Cr23 C6, Fe5 C2, Cr3 Si, CrSi2, Fe>0.64 Ni0.36, CFe15.1, C-(Fe,Cr)-Si phases formed in the microstructure. In comparison to the substrate, the microhardness of the coatings produced by PTA were 2.5–3.5 times harder.

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Magnesium and its alloys are considered as an important material for modern light structures at the present time and therefore they have a wide area of usage especially in electronics, aircraft, and automotive industries. Its popularity increases further as a result of its production as a composite material. In this study, carbon nanotube (CNT) reinforced MgAl matrix composite materials were produced by using the hot pressing method. While 0.25 wt%, 0.50 wt%, 0.75 wt%, and 1.00 wt% CNT were added, 450°C, 500°C, and 550°C was selected as sintering temperatures. The effect of sintering temperature and amount of CNT on some properties of the composites was examined. Microstructure and phase composition of the materials were examined by using optical microscopy (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The hardness of the composites was measured in Brinell. Relative densities of the materials were determined in accordance with Archimedes' principle. A dense and slightly porous structure was obtained based on both SEM images and density measurements. XRD analyses showed that there were Mg, Mg 17 Al 12 , and MgO phases in the composites. The reason for the absence of Al in graphics was that Al formed the solid solution by being dissolved in Mg. Also, the C peak could not be determined for CNT. The hardness of the composites increased with the increasing sintering temperature and CNT addition. The highest hardness value was measured as 88.45 HB10 with the addition of 1.00 wt% CNT at 550°C. Free distribution of CNT in the matrix caused this hardness increase.

ÖzBu çalışmada, plazma sprey yöntemi ile AISI 304 paslanmaz çelik üzerinde üretilen Ti3SiC2 MAX fazlı kaplamanın mikroyapı, aşınma ve korozyon özellikleri araştırılmıştır. Ti3SiC2 fazını üretmek için başlangıç malzemesi olarak Ti ve SiC tozları kullanılmıştır. Ti tozuna ağırlıkça % 35 SiC ilave edildikten sonra elde edilen toz karışımı atmosfer kontrollü plazma sprey tabancası ile alt tabaka üzerine kaplanmıştır. Kaplamanın mikroyapı ve faz oluşumunu incelemek için optik mikroskop, taramalı elektron mikroskobu ve XRD kullanılmıştır. Mikroyapı incelemeleri kaplama mikroyapısının lamelli bir yapıya sahip olduğunu göstermiştir. XRD analizlerine göre Ti3SiC2 MAX fazı kaplama tabakasında tespit edilmiştir. Mikrosertlikler, kaplama tabakasından alt tabakaya doğru bir hat boyunca ölçülmüştür. Kaplama ve alt malzemenin aşınma özellikleri, çizik testi ile tespit edilmiştir. Kaplama tabakasının sürtünme katsayısı alt malzemeye göre düşük çıkmıştır. Alt malzeme ve kaplamanın korozyon özellikleri %3,5 NaCl çözeltisinde potansiyodinamik ölçümler yapılarak belirlenmiştir. Korozyon sonuçları, kaplama tabakasının alt malzemeye göre 3,5 katlık bir korozyon direncine sahip olduğunu göstermiştir.

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