31 research outputs found
Non-destructive imaging of delicate polymer surfaces using scanning force microscopy tips modified with hydrophobic self-assembled monolayers
No full textNanoindentation and nanoscratch testing of uniaxially and biaxially drawn poly(ethylene terephthalate) film
No full textScanning force microscopy of plasma polymerised hexane: information on the mechanical properties of thin films from tip-induced wear
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Scanning force microscopy of bulk-filled uniaxially oriented poly(ethylene terephthalate) films
No full textDeformation of Si(100) in spherical contacts — Comparison of nano-fretting and nano-scratch tests with nano-indentation
No full textRelationship between mechanical properties of thin nitride-based films and their behaviour in nano-scratch tests
No full textEffect of deposition parameters on TiAlN coating using pulsed DC CFUBMS
No full textThis paper aims to investigate the parametric effect of deposition and target frequency on the mechanical properties and machining performance of the TiAlN coatings deposited in a dual cathode pulsed dc CFUBMS system. Coating composition is not directly dependent on deposition temperature or target frequency individually but increase in both the parameters has led to Al rich coating. The coating thickness is influenced by target frequency only. The fatigue fracture resistance of the TiAlN coating has been evaluated by the nanoimpact test and it has been found to be at least as good as commercial Ti0.5Al0.5N coating deposited on cemented carbide. In dry machining SAE 1037 steel, it has been observed that the resistance to crater wear is influenced by target frequency. Simultaneous increase in the deposition temperature and target frequency has provided improved resistance to crater wear due to their favourable influence on the coating thickness and Al percentage
Optimized scratch adhesion for TiSiN coatings deposited by a combination of DC and RF sputtering
No full textThis paper outlines an experimental study of the TiSiN coatings deposited using a combination of direct current (DC) and radio frequency (RF) PVD magnetron sputtering (DR-PVD) on high speed steel (HSS) substrates. An L9 Taguchi orthogonal array was used to conduct the experiments for finding the optimum process parameters. Four process parameters, (1) RF power, (2) DC power, (3) nitrogen to argon (N2/Ar) gas ratio and (4) deposition time were considered. The surface structure and composition of selected coating samples were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The critical load in the micro-scratch test was used as a measure of scratch adhesion. Investigations of the scratch tracks were viewed by an optical microscope. The results showed that higher scratch adhesion strength was achieved using RF power of 100 W, DC power of 500 W, N2/Ar ratio of 1:2.5 and a deposition time of 6 h. Optimization resulted in an increase of the critical load value from 827 mN to 1371 mN, signifying an improvement of over 65%
Nano-scratch testing of (Ti,Fe)Nx thin films on silicon
No full textThin films of (Ti,Fe)Nx have been produced on silicon wafers with a wide range of compositions and mechanical properties to investigate correlations between the mechanical properties measured by indentation and crack resistance in the highly loaded sliding contact in a nano-scratch test. The nano-scratch test data on the thin films using a well-worn Berkovich indenter with ~1 m end radius were supported by high resolution scanning electron microscopic (SEM) imaging and analytical stress modelling. The results show that mechanical properties of the coating, its thickness and the substrate properties all influence the deformation process. They affect the critical loads required, the type of failures observed and their location relative to the moving probe. The differences in coating mechanical properties affect how the interface is weakened (i.e. by initial substrate or coating yielding or both) and determine the deformation failure mechanism. The load dependence of the friction coefficient provides details of the sliding contact zone and the location of failure relative to the sliding probe. Improved performance was achieved at intermediate hardness and H3/E2 in the nano-scratch tests on thin films. The friction and modelling results strongly suggest that failure at low load on the hardest coatings is due to a combination of high tensile stress at the rear of the contact zone and substrate yield. Designing thin films for protective coatings with in-built dissipative structures (such as soft and low elastic modulus inclusions) and mechanisms to combat stress may be a more successful route to optimise their toughness in highly loaded sliding conditions than aiming to minimise plasticity by increasing their hardness
