As a standard for the calibration of force and depth scales of hardness testing instruments a system of silicon springs is described. The standard shows a linear force-deflection characteristic F = k · f up to a stop point (typical: Fst = 420 mN; fst = 22 µm). For the calibration of stiffness and stop point of the standard the characteristic should be measured using a spherical indenter. In view of the practical application for the assessment of instruments also Vickers indenters can be used. In this case indentations are produced. The resulting wear can be minimized by reducing the maximum...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
Since the ISO standards for four major hardness scales were revised in 2005, the indirect verification has been considered as the mainstream of the traceability chain of hardness. In the recommended procedure of ISO, the uncertainty of hardness machine should be estimated and added to the combined uncertainty of hardness measurement value. The equation to calculate this uncertainty component was introduced according to the rectangular distribution of bias of hardness machines. However, if the error propagation is investigated in detail, the uncertainty of hardness machines should be obtained...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
When the nanoindentation testing is carried out, it is very important to understand the residual impression and the surface around it. Generally Atomic Force Microscopy (AFM) is used to obtain them. However, it is necessary to understand correct shape in the point of cantilever in AFM procedure. And, measuring them by AFM procedure precisely, very long measurement time and very clean environment and so on are needed. So, there are many difficulties to use AFM procedure for measuring residual impression and the surface around it. On the other hand, there are some procedures to measure them....
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
Analysis of indentation depth dependence of elastic modulus of soft films on silicon substrate measured by nanoindentation was studied. The experimental results were compared with two existing models that describe the effects of the substrate on elastic modulus of layered solid. Saha-Nix model that is the recent modification of King model agreed well with the experimental results to a certain limit of the indentation depth. It was found that the depth limit which Saha-Nix model is valid depended almost linearly on the relative elastic modulus of the film to the substrate Ef/Es. We further...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
According to the principle of a conventional Vickers (Berkovich) hardness measurement, hardness is calculated from diagonal lengths or side lengths of indentation. The diagonal length, the conjunction line length of pyramidal indentation, and the distance from the vertex to the base of trigonal pyramidal indentation are measured accurately by observing a vertical cross section. Scanning probe microscopy (SPM) is a good method for observing the vertical and horizontal cross sections of the indentation. However, such parameters in the cross section profile must be defined as the principle of...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
Vytautas Vasauskas, Juozas Padgurskas, Raimundas Rukuiza
The influences of indenter micro-geometry on the micro-hardness performance in the film/substrate system are discussed. Experimental results verify the force required to produce hardness indents for thin films, the measurement of the size of plastic zone cross-sections of the indents, and the characterisation of the indenters. It was found that the deformation is highly localised beneath the indenter and failures in the corners of pyramidal indenters occurred.
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
Hardness test methods are widely used in mechanical properties test area. While reference materials are essential important tools to control test accuracy or uncertainty. According to current test method standards, the thickness of hardness reference materials must be not less than 6 mm for Rockwell hardness or not less than 5 mm for Vickers hardness. To measure thinner sample which is commonly used in industry, and to guarantee the test results, a thin sheet reference sample is demanded.
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
Hardness measurement methods for rubber and plastics are described in the standards ISO 7619-1, ISO 7619- 2, ISO 868 and ISO 48. Rising requirements for the accuracy of this hardness measurement have led to the result that the users of rubber hardness testers and also metrology experts who deal with their calibration need a calibration method to check the overall function of the testers acknowledged by a standard. Therefore extensive experiments were conducted in a cooperation between the Physikalisch - Technische Bundesanstalt (PTB) in Braunschweig (Germany) and the ZAG Ljubljana...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
The specific hardness deviations of a Rockwell diamond indenter can be determined by a group standard, consisting of several indenters, using correction functions. In this paper the establishment of an HRC group standard in the PTB and comparative investigations of the group standards in the PTB and the calibration laboratory MPA NRW in Germany are reported. Above all the group standard is advantageous for maintaining the stability of the Rockwell hardness scales.
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download
In order to perform traceable hardness measurements using Rockwell Hardness Indenters, the indenter must conform to the requirement of ISO 6508-3 standard. The standard defines specifications for the geometric parameters for this type of indenter. Conformance to this standard is of particular importance to all calibration laboratories which operate in accordance with ISO/IEC 17025. At present there is no facility in South Africa with the capability of calibrating indenters for conformance to ISO 6508-3. This situation is being addressed through a series of studies currently being conducted...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement · TC5 · 2007 · Download