Strength measurements of thin brittle ZrO2 coatings produced by magnetron sputtering on steel substrates

✍ Scribed by M Andritschky; P Alpuim

• Book ID: 104265869
• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 743 KB
• Volume: 48
• Category: Article
• ISSN: 0042-207X
• DOI: 10.1016/s0042-207x(97)00004-3

✦ Synopsis

Conventional techniques for determining mechanincai properties usually cannot be appiied to ceramic, coatings because of the difficulties in handling thin brittle films with a thickness of about 5pm. However, analysis of crack spacing resulting from a four-point bending test of coating and substrate may reveal some mechanical coating properties of the coating such as tensile strength, WeibuN modulus, adhesion and eventually the intrinsic thin fi/m stress. To examine this ZrO, stabi~jsed by Y,U, {YSZ) coatings were deposited by reactive magnetron spu~erjng on Inconel617 substrates. These samples were subjected to tensile loading during four-point bending tests within a Scanning Electron Microscope. The crack spacing was initially examined and the load applied and subsequently increased in several steps up to 1.0 GPa. A simulation of the crack spacing, taking into account a finite adhesion of the coating on the substrate and stress relaxation in the vicinity of the cracks due to elastic and piastic deformation of coating and substrate, reveals the mechanical prope~ies of the coating. depending on deposition conditions and surface preparation, the ~ejbu~i modulus was

m w 2.6 and a fracture stress at the first faiiure z 20-3500 MPa for the YSZstabXzed coatings depending on the residual compressive stress. The fracture toughness was generally K,c< 3.6 MPa m 1'2.