Influence of oxygen flow rate on the structural and mechanical properties of reactively magnetron sputter-deposited Zr-B-O coatings

Zr-B-O coatings were deposited on both construction steel and stainless ste el substrates by magnetron sputtering of ZrB2 targets in reactive Ar-O-2 ga seous mixtures. In this paper, the deposition rate and the structural and m echanical properties of Zr-B-O films will be investigated as a function of the inlet oxygen flow rate. We will show that two domains are available owi ng to the sputtering phenomena. In the former, the coating enrichment is qu ite proportional to the oxygen how rate. Even for a weak oxygen enrichment, amorphization of the Zr-B-O films is observed which also decreases both th eir intrinsic internal stress and microhardness, thus improving the physica l quality of the coatings. As the oxygen flow rate increases, the amorphous coatings, initially composed of a single-phase ZrB2-xOx solid solution, pr esent an increasing fraction of amorphous ZrO2, and then, of amorphous B2O3 simultaneously with the disappearance of the metallic solid solution. High er oxygen flow rates allow the synthesis of optically transparent amorphous oxide mixture films, the composition and mechanical properties of which be come independent of the inlet oxygen flow rate. (C) 1999 Elsevier Science S .A. All rights reserved.