Title: Developing PVD zirconium-oxide coatings for use of thixoforming of steel

Authors: Kirsten Bobzin, Erich Lugscheider, Michel Maes, Philipp Immich

Addresses: Surface Engineering, RWTH Aachen University, Augustinerbach 4–22, 52062 Aachen, Germany. ' Surface Engineering, RWTH Aachen University, Augustinerbach 4–22, 52062 Aachen, Germany. ' Surface Engineering, RWTH Aachen University, Augustinerbach 4–22, 52062 Aachen, Germany. ' Surface Engineering, RWTH Aachen University, Augustinerbach 4–22, 52062 Aachen, Germany

Abstract: The process of semisolid metal forming with permanent moulds combines the advantages of the casting and forging process technologies. The processing of steel results in high loads on the surface of the metallic die, such as thermal, mechanical and tribological stresses. To meet this challenge, ceramic-based Physical Vapour Deposition (PVD) hardcoatings are used for tool protection to guarantee high durability of the tool. The first experiments show that especially the high-temperature tetragonal zirconia phase exhibits high strength and toughness. To propose and to examine the appropriate coatings to extend the surface lifetime of the metallic moulds, zirconia coatings were synthesised using pulsed reactive magnetron sputtering. After deposition, these coatings were analysed by common thin film techniques revealing hardness, Young|s modulus and x-ray diffraction measurements. The conclusion was that the examination of t-ZrO₂ showed the extraordinary potential of these thin films for use as coating for thixoforming dies.

Keywords: PVD coatings; thixoforming dies; zirconium oxide; reactive sputter process; compression tests; semi-solid metal forming; physical vapour deposition; high strength; toughness; thin films; steel.

DOI: 10.1504/IJMMP.2008.018733

International Journal of Microstructure and Materials Properties, 2008 Vol.3 No.2/3, pp.262 - 270

Published online: 16 Jun 2008 *

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