W + Cu and W + Ni Composites and FGMs Prepared by Plasma Transferred Arc Cladding.

Jiří Matějíček,Jakub Antoš,Pavel Rohan

doi:10.3390/ma14040789

Abstract

Tungsten-based materials are the most prospective candidates for plasma-facing components of future fusion devices, such as DEMO. W-based composites and graded layers can serve as stress-relieving interlayers for the joints between plasma-facing armor and the cooling or structural parts. Coating/cladding techniques offer the advantages of eliminating the joining step and the ability to coat large areas, even on nonplanar shapes. In this work, W + Cu and W + Ni composites were prepared by pulsed plasma transferred arc (PTA) cladding on several different substrates. Optimization of the process was carried out with respect to powder mixture composition and process parameters like arc current, plasma gas composition, and traverse velocity. Dense claddings of several millimeters thickness and various W content were achieved. Moreover, multilayers with W content gradually varying from 47 to 92% were formed. The structure, compositional profiles, and thermal properties of the claddings were characterized.

Highlights

Materials 2021, 14, 789. https://Plasma-facing components (PFCs) for future fusion reactors will have to withstand extremely harsh conditions involving high heat fluxes and bombardment of plasma species [1]
The present work explores the possibility of preparing W + Cu and W + Ni composites by plasma transferred arc (PTA) cladding
Very dense layers were observed in all cases

Summary

Introduction

Plasma-facing components (PFCs) for future fusion reactors will have to withstand extremely harsh conditions involving high heat fluxes (both steady-state and thermal shocks) and bombardment of plasma species (ions, electrons, neutral atoms, and high-energy neutrons) [1]. Plasma transferred arc (PTA) cladding (sometimes called PTA surfacing, hardfacing, or overlay welding) is a deposition technique that uses plasma to melt the filler material and substrate. The present work explores the possibility of preparing W + Cu and W + Ni composites by PTA cladding To our knowledge, this is the first application of the technique on materials with potential application in plasma-facing components of fusion devices. The objectives were to test the prospective advantages outlined above, i.e., formation of dense layers with significant material throughput without the need for additional bonding, and the compositional control. The latter included the demonstration of FGM formation and exploration of the limits in tungsten content. Basic optimization was carried out with respect to powder mixture composition and process parameters, and the claddings were characterized for their structure, compositional profile, and thermal properties

Experimental

Morphologies

Results

21.7 Ni–W–Fe solid solution

Conclusions