Effects of cyclic plasma heating on surface damage of micro-porous tungsten. (28th September 2021)

• Record Type: Journal Article
• Authors: Ghazari, Arian; McElfresh, Cameron; Dickstein, Dylan; Marian, Jaime; Ghoniem, Nasr
• Is Part Of: Physica scripta. Volume 96:Number 12(2021)
• Publication Date: 2021-09-28
• Subjects: porous tungsten -- DBTT -- residual stress -- fracture -- thermal shock -- tungsten -- recrystallization; Physics -- Periodicals; 530.05
• DOI: 10.1088/1402-4896/ac2857
• Languages: English
• ISSNs: 0031-8949

Abstract

Abstract: The operating temperature window of solid tungsten (W) is dictated by its Ductile to Brittle Transition Temperature (DBTT) and re-crystallization temperature; roughly between 300-1300 °C. The brittleness of W at lower temperatures is exasperated when it undergoes recrystallization. We investigate here the thermal shock resistance of micro-porous W as a meta-material fabricated in a 3D open-cell network structure. We present experimental results for the effects of cyclic high-enthalpy arc-jet plasma on surface damage in three testing categories. Observed damage includes surface ablation of asperities, melting and solidification of W-fuzz on samples that have been exposed to a prior helium plasma, and micro-cracks at ligament triple junctions. Scanning electron microscope (SEM) observations show more micro-cracking on 54% and 23% foams compared to the 43% ones. In all tested samples, thermal expansion/contraction displacements were accommodated by ligament rotation and a network of micro-cracks. No large through-thickness crack were observed.