Article

Indenter Methods of Determining the Adhesive and Cohesive Strength of Thin Coatings

Authors:
  • A.A. Blagonravov Institute of Machine Science Russian Academy of Sciences
To read the full-text of this research, you can request a copy directly from the author.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the author.

Article
This review analyzes the problems caused by heavy wear of loaded friction elements of structures, which is typical of almost all industries. This implies the importance of solving problems of increasing their durability. Of particular relevance is the need to solve the problem of improving wear resistance of contact surfaces of special-purpose shut-off valves, being an irreplaceable component of technical equipment used in the oil and gas industry as well as processing industries, nuclear energy, and medicine. It is shown that the effectiveness of solving problems of increasing durability of equipment is largely associated with additional standard processing of loaded friction elements of such structures, and with the improvement of technologies for increasing wear resistance and strength characteristics of their contact surfaces. The analysis of the possibilities of increasing wear resistance by mechanical methods of surface treatment, as well as by methods of surface modification through various functional coatings has been made. It is substantiated that the vacuum-arc method of ion-plasma spraying of a multilayer nanocomposite coating is the most promising way of creating a functional coating to increase the wear resistance of valves. Widespread industrial introduction of the method of beam surface modification of materials makes it possible to obtain such structural-phase states of materials, which are not possible with traditional methods.
Article
Full-text available
To measure nanomechanical properties of surface layers of bulk materials and thin films, depth-sensing nanoindentation measurement techniques are used commonly. The nanoindentation apparatus continuously monitors the load and the position of the indenter relative to the surface of the specimen (depth of an indent or displacement) during the indentation process. Indentation experiments can be performed at a penetration depth of as low as about 5 nm. This paper presents an overview of various nanoindentation techniques, various measurement options, and data analysis. Data on elastic–plastic deformation behavior, hardness, elastic modulus, scratch resistance, film-substrate adhesion, residual stresses, time-dependent creep and relaxation properties, fracture toughness, and fatigue are presented.
Article
Full-text available
This review summarized the research works on the characterisation of interfacial adhesion in thin film/substrate bilayer structure by use of indentation testing. It focused on the delamination mechanics between a thin film and a substrate induced by indentation and the quantitative characterisation of interfacial strength in such bilayer systems. Three major techniques were introduced, namely conventional indentation, cross-sectional indentation and acoustic emission assisted indentation. A number of theoretical models and finite element simulation studies were discussed, in association with the experimental investigations.
Article
This paper demonstrates the potential for obtaining theoretical analytical relationships describing the loading and unloading curves of instrumental indentation in topocomposites. A connection is established between the theory of instrumental indentation in compact materials composing a topocomposite and the theoretical dependences proposed in this paper that describe an indentation diagram for topocomposites. The results obtained are intended to analyze the experimental indentation diagrams obtained for surface-layered solids.
Article
Diamond-coated cutting tools are economically attractive alternatives to polycrystalline diamond tools for machining applications. Despite the superior tribological and mechanical properties, the advantages of diamond-coated tools, however, have been largely compromised by the insufficient coating–substrate adhesion. Interface characteristics are important in the failure and performance of diamond-coated tools. In this study, a cohesive zone model was incorporated to investigate diamond-coating tungsten carbide (WC) systems. The cohesive zone model is based on the traction–separation law, represented by four parameters: the maximum normal and shear strength and the normal and shear characteristic lengths, whose values were determined from WC fracture properties. The cohesive zone model was implemented in finite element codes to simulate indentation on a coating–substrate system.The model was applied to examine the interface behavior during the indentation, the role of the cohesive zone in the failure mechanism of coating systems, and the coating Young's modulus and thickness effects on different failure modes. The simulation results are summarized as follows. (1) The cohesive zone interface does not affect the critical load for coating surface tensile cracking, but affects the plastic strain during loading. (2) If the coating Young's modulus increases, the coating surface cracking will decrease, however, the interface delamination resistance will increase. (3) Increasing the coating thickness will generally increase the critical load for surface cracking, but will have an opposite effect when the coating exceeds a certain thickness. Moreover, thicker coatings typically reduce the interface delamination.
Article
We consider the effect of an elastic modulus that decreases with depth on the load-displacement relation for indentation of a graded half space by a rigid indenter. A closed-form approximation incorporating features of the plate on an elastic substrate and the Hertzian contact theory is compared with finite element results for the case of a uniform stiff layer on a homogeneous substrate. Some general results are presented for the case where the grading has inverse power-law form and the effects of truncation to a finite surface value are investigated numerically. Finally, a more practical error-function grading is considered. In all cases, the load-displacement relation is closer to linear than in the homogeneous case. We conclude that the experimental data can be used to determine parameters in a predetermined form of grading, but that comparative insensitivity to the exact form of the grading would make it difficult to distincguish experimentally between different models based on indentation experiments alone.
Article
Indentation forces, including constant rate and oscillating mode, were applied to SiO(2)/Si and diamond-like carbon (DLC)/Si specimens. A two-stage behavior was exhibited in the force-depth results after delamination occurred. When the depth was smaller than the threshold value, a linear load-depth relationship was exhibited because the debonded film was suspended over the substrate. Membrane theory was applied to analyze the deflection of the suspended film, and thus the in-plane stress exhibited in the debonded film was evaluated. Through the proposed method, the strain energy release rate of the interface can be directly evaluated by analyzing the force-depth data of the indentation tests.
Creation of topocomposites for tribotechnical purposes
  • N A Voronin
Theoretical assessment of the composite and true hardness of thin coatings
  • N A Voronin
Effect of coating thickness and substrate material on mechanical properties and carrying capacity of hardened surfaces
  • N A Voronin
  • G V Moskvitin
  • Ed
Nanoindentirovanie i ego vozmozhnosti (Nanoindentation and Its Capabilities)
  • Yu I Golovin
Delamination of a strong film from a ductile substrate during indentation unloading
  • A Abdul-Baqi
  • E Van Der Giessen