ALTERNATIVE SOLUTIONS IN AIRCRAFT ENGINE APPLICATIONS: USAGE OF MoSi2 BASED MATERIALS AS STRUCTURAL ELEMENTS

Yıl 2016, Cilt: 57 Sayı: 679, 44 - 52, 30.08.2016

Yağız Uzunonat

Öz

MoSi2 based composites are candidate materials which can be used as structural elements in oxygenrich atmospheres especially in aircraft applications for their excellent mechanical properties and low
density against agressive conditions at high temperatures. In this study, after giving some limits of
traditional structural aircraft engine materials, essential mechanical and physical properties of MoSi2
were analysed. Oxidation and thermal shock behaviors (which are considered to be the most important factors in structural high temperature applications) were also determined. It was showed that
low fracture toughness and pest oxidation at average temperatures (~500°C) can be easily eliminated
by additions of Si3N4 in different portions to the material. The obtained data proves that mechanical
abilities of MoSi2 based materials can respond to speed/performance/cost requirements of aircraft
technologies.

Anahtar Kelimeler

Molybdenum disilicide, oxidation resistance, superalloys, fracture toughness, aircraft engine

UÇAK MOTORU UYGULAMALARINDA ALTERNATİF ÇÖZÜMLER: MoSi2 ESASLI MALZEMELERİN YAPISAL ELEMAN OLARAK KULLANIMI

Öz

MoSi2 esaslı malzemeler, yüksek sıcaklıklardaki oksijen zengini ortamlarda zorlayıcı koşullara karşı gösterdikleri mükemmel dayanımları ve süperalaşımlara oranla sahip oldukları düşük yoğunluk
sebebiyle, özellikle havacılık uygulamalarındaki uçak motoru parçaları için yapısal eleman olarak
kullanılmaya aday özelliktedir. Çalışmada, öncelikle geleneksel uçak motoru yapısal malzemeleri uygulamalarındaki başlıca kısıtların verilmesinin ardından, MoSi2’nin temel mekanik ve fiziksel özelliklerinin analizi gerçekleştirilmiş ve yapısal yüksek sıcaklık uygulamalarındaki en önemli unsurlar
olarak kabul edilen oksidasyon ve ısıl şok özellikleri incelenmiştir. Malzemenin Si3N4 ile oluşturduğu
çeşitli kompozit yapıların, kırılma tokluğu değerlerini ve servis koşullarındaki ortalama sıcaklıklarda
(~500°C) oksidasyon dayanımını büyük oranda iyileştirdiği ortaya konmuştur. Elde edilen veriler
değerlendirildiğinde, MoSi2 esaslı malzemelerin mekanik kabiliyetlerinin gelişen teknolojiye bağlı
olarak uçaklardan istenen hız/performans/maliyet kriterlerini karşılayabileceği görülmektedir.

Anahtar Kelimeler

Molibden disilisit, oksidasyon dayanımı, süperalaşımlar, kırılma tokluğu, uçak motoru

Kaynakça

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