Publications (3)1.69 Total impact
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ABSTRACT: Exeriments for determining the adhesion strength between TiN coatings and high-speed steel substrates have been performed using the three-point bending test and a modified shear test. Sample preparation is easier for the modified shear test, however, interpretation of results is more complicated. The three-point bending test yields fracture mechanics data, such as the interface fracture energy Gc and the fracture toughness Kc. The most critical problem is to prepare a sample with a notch which initiates crack propagation at the film/substrate interface. Various sublayers with weak adhesion have been tested as a notch, such as carbon, oxide and metals, as well as thin mechanical slits. The results obtained so far demonstrate that the adhesion strength depends on the substrate cleaning treatment and on the impurity gas content in the receiver. Typical values of the fracture toughness Kc for non-sputtercleaned substrates are in the range 1–3 MN . Advantages and disadvantages of various methods used are analysed and critically discussed with respect to sample preparation, reproducibility and data evaluation.International Journal of Refractory Metals and Hard Materials 14:207-211. · 1.69 Impact Factor
Article: Mechanical properties and adhesion strength of TiN and Al coatings on HSS, steel, aluminium and copper characterized by four testing Methods[show abstract] [hide abstract]
ABSTRACT: TiN and Al coatings on substrates of high-speed steel, steel, aluminium and copper have been used to study mechanical properties of coating systems, especially the adhesion of the coating. The quantities measured are internal stress of the coating, determined by X-ray diffraction, the critical load of the scratch test, the microhardness obtained by the indenter technique, and the interface fracture energy, determined by a three-point bend test developed recently by the authors. The fracture energy, Gc, is a measure for the adhesion strength of a coating system. The effect of bias voltage, sputter cleaning and contamination of the substrates on the adhesion strength and other mechanical properties are investigated with the four methods mentioned. Each of the testing methods reveal only specific aspects of the behaviour of the coating systems. The data obtained depend on bulk properties of the film and the substrate material and on properties of the interface. Variation of the bias voltage can change them in quite different ways. In addition, the inter-relations between the adhesion strength of the coating and the failure behaviour of the three-point bend test samples are discussed.Thin Solid Films.
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ABSTRACT: Experiments for determining the adhesion strength between TiN or Al coatings and high speed steel (HSS) have been performed by using the three-point bend test and a modified shear test. Sample preparation is easier for the modified shear test; however, the interpretation of the results is more complicated. The three-point bend test yields fracture mechanics data such as the interface fracture energy, Gc, and the fracture toughness, Kc. A copper sublayer with weak adhesion has been used as a notch which initiates crack propagation at the coating/substrate interface. The fracture mechanics tests were complemented by scratch tests and microindenter measurements. The effects of coating thickness and of oxygen contaminations in the sputtergas atmosphereduring deposition of TiN coatings, or of substrate sputter cleaning on the adhesion of Al coatings has been investigated with several sets of samples after an identical pretreatment. Interface fracture toughness values are in the range of for TiN coatings and 0.75 to for Al coatings.Thin Solid Films.