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 chapter 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.

Nanomechanical characterisation of solid surfaces and thin films

Modern coating techniques now offer the possibility of modifying the surface of an engineering component to achieve improvements in both performance and reliability. One important and often overriding factor is the degree of adhesion between the coating and its substrate, and the aim of this paper is to discuss the methods which can be used to assess this critical property of the coating-substrate system. The advantages and disadvantages of each technique, e.g. the pressure-sensitive tape test, indentation testing, the scratch test, laser methods etc., are reviewed.

A review of the methods for the measurement of coating-substrate adhesion☆

Adhesion measurements of chemically vapor deposited and physically vapor deposited hard coatings on WCCo substrates

The indentation of a brittle film on a ductile substrate is analysed for obtaining the interface toughness This measurement method of adhesion provides a simple technique for sampling a small area of the interface on practical geometries with common laboratory equipment Mechanics solutions are presented to access the interface toughness, I 9c, from measurements of the applied load, delamination radius, film thickness and film-substrate material properties The test is found to be particularly effective for films under large residual compression Measurements of the interface toughness ( I 9c ~ 45 J m -2 ) are made for a diamond-coated titanium alloy

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Measurement of the adhesion of a brittle film on a ductile substrate by indentation

A new method has been developed for checking the mechanical quality of thin coatings by determining their resistance to small-scale abrasion. The method is capable of determining the wear constants for the coating and the substrate individually, even for very thin coatings. The theory for imposed shape wear scars is introduced. Suitable parametersaand test procedures are proposed and the repeatability, experimental scatter and general capability of the method are presented. The method has the following advantages: 1. (1) The intrinsic abrasion resistance of the coating and the substrate are measured individually. In contrast to competing wear tests which evaluate the wear resistance of the composite rather than the coating and the substrate individually, these values are independent of the wear scar size. 2. (2) Very thin coatings can be evaluated. In the most favourable situation, where the coating has a considerably higher abrasion resistance than the substrate, the wear constant of coatings of sub-micron thickness can be readily determined. 3. (3) The small volume needed makes the test virtually non-destructive. For example it is fully possible to test the coating of a cutting insert before using it in a tool life test. 4. (4) The craters are produced in a commercially available dimple grinder, which remains useful for its original purposes of preparing transmission electron microscopy samples and coating thickness measurements.

A new test method for the intrinsic abrasion resistance of thin coatings

This paper describes specialized methods for measuring coating adhesion, microhardness, and microfracture toughness of hard coatings. Coating adhesion is an interfacial property which may be characterized by scratch or indentation techniques which yield a decohesion critical load or an interfacial fracture toughness parameter. Microhardness measurements are shown to be satisfactory if light indenter loads are applied to polished coating surfaces; microhardness profiles may be measured at room and elevated temperatures on a taper section of the coating. The Palmqvist microfracture toughness of hard coatings may additionally be determined from the same microhardness indentations.

D. T. Quinto

Papers

Techniques for evaluating mechanical properties of hard coatings