D. A. Hirschfeld, New Mexico Institue of Mining and Technology, Socorro, NM; S. Price, New Mexico Institute of Mining and Technology, Socorro, NM; K. J. Hollis, Los Alamos National Laboratory, Los Alamos, NM
Plasma spray forming has been used to produce yttria castware for reactive metals. To achieve improved toughness and strength of castware, specifically crucibles and pour tubes, the yttria castware is strengthened using a functionally graded coating of Ni-Al alloy. Thermal stress models are used to optimize the composite gradient. Results of the modeling and testing will be discussed.
Summary: Thermal stresses can cause premature failure of the castware, especially in reactive metal casting where traditional materials and techniques cannot be used. Plasma spray forming of free-standing parts shows promise for creating funcionally graded castware. An inert yttria layer in contact with melt will transition to a tough nickel-alloy (Metco XP-1104) layer. Plasma spray parameters and thermo-mechanical properties are described in this paper.
