Experimental assessment of micromechanical models for fragmentation analysis of thin metal oxide coatings on polymer films under uniaxial tensile deformation

SURFACE & COATINGS TECHNOLOGY

卷:370

Article

da Costa, Marcus Vinicius Tavares¹  Bolinsson, Jessica²  Neagu, R. Cristian²  Fayet, Pierre³  Gamstedt, E. Kristofer¹ 

[1] Uppsala Univ, Div Appl Mech, Dept Engn Sci, Box 534, SE-75121 Uppsala, Sweden

[2] Tetra Pak Packaging Solut AB, Ruben Rausings Gata, SE-22186 Lund, Sweden

[3] Adhemon Sarl, Thin Technol, Ave Edouard Dapples 20, CH-1006 Lausanne, Switzerland

关键词: Interfacial shear strength;    Coating strength;    Fracture toughness;    Weibull shape parameter;    Fragmentation test;    Metal oxide coatings;    Atomic layer deposition;   

DOI  :  10.1016/j.surfcoat.2019.03.035

来源: Elsevier

【 摘 要 】

The barrier properties of metal oxide coatings deposited on polymer substrates is of interest in packaging applications for beverages and food. The durability of the coatings is compromised mechanically due to brittleness of the coatings, leading to multiple cracking when deformed. This cracking behavior has been investigated in situ for atomic layer deposited coatings of TiO2 (6 and 20 nm thick) and mixed oxides of TiO2 and Al2O3 (4 and 20 nm thick) on polyethylene terephthalate substrate films by observing multiple cracking under uniaxial tension. Two key models to identify cohesive and adhesive properties from the fragmentation data have been implemented, and their differences are discussed in light of the new experimental data. Such material properties include the Weibull strength distribution of the coating, the interfacial shear strength, the strength at crack saturation, and fracture toughness at crack onset and at saturation. These properties can be useful for materials selection and possibly for design simulations, when the unaccounted effects like finite deformation and substrate yielding do not take over. A significantly weaker interface and cohesive strength was observed for the thinner mixed-oxide coating, where the dimensions of the material heterogeneities were of the same order as the coating thickness. These dimensions seem to be the limiting factor of how thin coatings can be made without a major loss in structural integrity.

【 授权许可】

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