The Tribaloy T-800 Coatings Deposited by Laser Engineered Net Shaping (LENS^TM)

• Main Authors: Tomasz Durejko, Magdalena Łazińska, Julita Dworecka-Wójcik, Stanisław Lipiński, Robert A. Varin, Tomasz Czujko
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Materials
• Subjects: tribaloy-type alloy; CoCrMoSi alloy coatings; T-800 alloy; Laves phase; Laser Engineered Net Shaping (LENS^TM)
• Online Access: https://www.mdpi.com/1996-1944/12/9/1366

A Tribaloy family of alloys (CoMoCrSi) are characterized by a substantial resistance to wear and corrosion within a wide range of temperatures. These properties are a direct result of their microstructure including the presence of Laves phase in varying proportions. Tribaloy T-800 exhibits the highest content of Laves phase of all other commercial Tribaloy alloys, which provides high hardness and wear resistance. On the other hand, a large content of the Laves phase brings about a high sensitivity to brittle fracture of this alloy. The main objective of this work was a development of the Tribaloy T-800 coatings on the Ni-based superalloy substrate (RENE 77), which employs a Laser Engineered Net Shaping (LENS^TM) technique. Technological limitations in this process are susceptibility of T-800 to brittle fracture as well as significant thermal stresses due to rapid cooling, which is an inherent attribute of laser techniques. Therefore, in this work, a number of steps that optimized the LENS^TM process and improved the metallurgical soundness of coatings are presented. Employing volume and local substrate pre-heating resulted in the formation of high quality coatings devoid of cracks and flaws.