Kutu Sementasyon Tekniğiyle GGG70 Küresel Grafitli Dökme Demir Yüzeyine Kaplanan NbC Tabakasının Özelliklerine Kaplama Sıcaklığın Etkisin İncelenmesi

Öz

Küresel Grafitli Dökme Demirler yüksek dökülebilirlik, yüksek mukavemet, titreşimi sönümleme ve yüksek yüklenme kapasitesi ile ön plana çıkmaktadırlar. Günümüz teknolojileriyle beraber malzemelerin yüzey özellikleri çeşitli yöntemlerle kaplanarak geliştirilebilir ve yüksek performanslı mühendislik malzemeleri elde edilebilmektedir. Kutu Sementasyon Tekniği, kaplama yöntemleri arasında nispeten daha düşük maliyeti ve uygulanabilirliği ile tercih sebebidir. Bu çalışmada GGG70 Küresel Grafitli Dökme Demir yüzeyinde 900 °C, 1000 °C ve 1100 °C’de 6 saat süreyle Kutu Sementasyon Tekniği ile yüzeyde NbC kaplanması amaçlanmıştır. Elde edilen kaplama tabakalarının özelliklerine sıcaklığın etkisi araştırılmıştır. Bu amaçla örneklerin yüzey morfolojileri incelenmiş, kırılma toklukları ve sertlik değerleri elde edilmiştir. Kaplama morfolojileri XRD, optik mikroskop ve SEM analizleri ile incelenerek kaplama yapısındaki ve kalınlıklarındaki değişimler elde edilmiştir. Sonuçlar incelendiğinde kaplama sıcaklığının artışı ile kaplama kalınlıklarının arttığı ancak -Fe fazının şiddetinin önce azaldığı ve sonra arttığı tespit edilmiştir. Buna bağlı olarak kaplamalardan alınan kırılma tokluk değerinin önce artıp sonra bir miktar azaldığı görülmüştür. Mikrosertlik değerleri kaplama bölgelerinde yaklaşık 5 kat artmıştır.

Anahtar Kelimeler

• Küresel Grafitli Dökme Demir
• NbC Kaplama
• Kırılma Tokluğu
• Mikrosertlik.

Investigation on the Effect of Coating Temperature on the Properties of NbC Layer Coated with Pack Cementation Technique on GGG70 Nodular Graphite Cast Iron Surface

Abstract

Nodular Graphite Cast Irons stand out with their high castability, high strength, vibration damping and high loading capacity. With today's technologies, the surface properties of materials can be improved by coating them with various methods and high-performance engineering materials can be obtained. Pack Cementation Technique is preferred among coating methods due to its relatively lower cost and applicability. In this study, it was aimed to coat NbC on the surface of GGG70 Nodular Graphite Cast Iron using the Pack Cementation Technique at 900 °C, 1000 °C and 1100 °C for 6 hours. The effect of temperature on the properties of the resulting coating layers was investigated. For this purpose, the surface morphologies of the samples were examined and their fracture toughness and hardness values were obtained. Coating morphologies were examined by XRD, optical microscope and SEM analysis and changes in coating structure and thickness were obtained. When the results were examined, it was determined that the coating thickness increased with the increase in coating temperature. Accordingly, it was observed that the fracture toughness value of the coatings first increased and then decreased slightly. Microhardness values increased approximately 5 times in the coating areas.

Keywords

• Nodular Graphite Cast Iron
• NbC Coating
• Fracture Toughness
• Microhardness

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