Cihan Özorak

Characterization of hot pressed CuAl–TiC composites with different TiC grain sizes

In this study, the CuAl–TiC composite materials were produced using hot pressing process. Effect of TiC grain size (0.2, 4 and 20 μm) on some properties of these materials was investigated experimentally. Production of CuAl–TiC composites was carried out under pressure of 35 MPa, at 700°C, and for a sintering time of 5 minutes. SEM-MAP studies showed that the TiC grains were relatively homogeneously distributed in the CuAl matrix. Microstructure analysis revealed that the composite materials consist of Cu, Al, Cu9Al4, CuAl2 and TiC phases. With the decreasing of TiC grain size, the hardness, transverse rupture strength, relative density and sintered density of composites increased.

TRD YÖNTEMİYLE SUPAP ÇELİĞİ YÜZEYİNDE ÜRETİLEN KAPLAMALARIN MİKROYAPI VE AŞINMA ÖZELLİKLERİ

Bu calismada, kullanim yeri itibariyle surekli asinmaya maruz kalan supaplarin Termoreaktif Difuzyon (TRD) teknigi kullanilarak karisik nitrur esasli kaplamalarla ile kaplanmasi ve mikroyapi ozelliklerinin incelenmesi gerceklestirilmistir. Bu amacla, supap yuzeyine once nitrurasyon islemi uygulanmistir ve sonra TRD yontemiyle supap yuzeyine bor gecistirilmistir. Uretilen kaplamalarin mikroyapi ve faz bilesimi incelemesi, taramali elektron mikroskobu (SEM), X-isin difraktogrami (XRD), X isini enerji dagilim spektrometresi (EDS) ile yapilmistir. Kaplamalarin sertlikleri vikers olarak olculmustur. Kaplamalarin asinma davranisi, tum numunelere ayni kosullarda uygulanan ball on disk asinma testleri yapilarak karsilastirilmistir. Kaplamalarin surtunme katsayilari nispeten dusuk cikmistir.

Yüksek Hızlı Oksi Yakıt ile Üretilen WCCo-Mo Esaslı Kaplamaların Mikroyapı Karakterizasyonu

Bu calisma, yuksek hizli oksi yakit (HVOF) isil puskurtme yontemi ile SAE 4140 celigi uzerinde uretilen WCCo-Mo kompozit kaplamalarin mikroyapisal ozelliklerini arastirmak icin yapilmistir. Bu amac icin WCCo tozlarina ilave edilen Mo miktari % ag. 10, 20, 30 ve 40 olarak degistirilmistir. Kaplamalar, faz bilesimi, mikroyapi ve sertlik ozellikleri acisindan karsilastirilmistir. Kaplama tabakalarinin faz bilesimi ve mikroyapisi X-isini difraktogrami (XRD) ve taramali elektron mikroskobu (SEM) ile incelenmistir. XRD sonuclari, WCCo-Mo kaplama tabakasinin WC, W2C, Co3W3C, Mo2C, MoO2, Mo ve Co fazlardan olustugunu gostermistir. Kaplamalarin sertligi Mo artisi ile artmistir. The present study has been carried out in order to investigate the microstructural properties of WCCo-Mo composite coatings deposited onto a SAE 4140 steel substrate by high velocity oxygen fuel (HVOF) thermal spray. For this purpose, the Mo quantity added to the WCCo was changed as 10, 20, 30 and 40 wt. % percents. The coatings are compared in terms of their phase composition, microstructure and hardness. Phase compound and microstructure of coating layers were examined using X-ray diffractometer (XRD) and scanning electron microscope (SEM). XRD results showed that WCCo-Mo composite coatings were mainly composed of WC, W2C, Co3W3C, Mo2C, MoO2, Mo and Co phases. The average hardness of the coatings increased with increasing Mo content. Anahtar kelimeler: Mo, WCCo, HVOF, Mikroyapi, Sertlik