Electrical Properties of Half Heusler coatings depending of spray process

Electrical Properties of Half Heusler coatings depending of spray process

G. Darut, M.-P. Planche, L. Vitu, H. Liao

ICB PMDM LERMPS, UTBM, 90010 Belfort, France

C. Candolfi, B. Lenoir,

Matériaux à propriétés thermoélectriques, Institut Jean Lamour

Campus Artem, BP 50840, 54011 Nancy Cedex - France

Microstructure and physico-chemical properties of a thermally sprayed coating depend on the dynamics of the particles interacting with the spray jet. According to the process used (plasma, flame, etc.), porosity and phase composition could be different. This is especially the case for electrical properties. In this study, different spray processes (APS; VPS and CS) were investigated to spray Half Heusler powders. For that, the thermoelectric powders of Hf₆₀Zr₄₀NiSn₉₈Sb₀₂ (n-kind) and Hf₂₀Zr₇₅Ti₀₅CoSb₈₀Sn₂₀ (p-kind) were selected due to their highly interesting electrical properties. The spray processes were evaluated through the measures of in-flight particles characteristics leading to interpret the properties of the formed coatings in term of microstructure, composition and mechanical properties. The efficiency of the HH coating was finally determined by measuring the material’s dimensionless figure of merit. The evolution in ZT was analyzed in function of the sprayed parameters. The results revealed significant modifications in coating properties due to the changes of coating quality.