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Исследование свойств конструкционных материалов методом инструментального индентирования с помощью портативного нанотвердомера
Abstract
A modification of the "NanoScan-4 D" nanohardness meter, which allows of measuring the mechanical properties of articles by the instrumental indentation according to GOST R8.748-2011 under conditions close to industrial fabrication, has been developed. The main advantage of the described device, unlike most modern portable hardness testers, is the ability to work with a wide class of materials (from metals to solid polymers) since the study of the mechanical properties of products does not require preliminary information on the elastic modulus of the material being tested. Presented are the experimental data obtained on standard samples of the enterprise: polycarbonate and aluminum, as well as on various metal articles used as parts of machines and mechanisms of the oil and gas industry. The measured values of hardness coincide with the values obtained on a laboratory nanohardness meter taking into account the inherent errors of this type of equipment.
Fluorocarbon (C : F) nanofilms up to 60 nm thick are synthesised on a titanium surface. The films are obtained by annealing thin layers of fluorocarbon oil (FO) (with an area of 0.6 cm ² ) in air with pulsed (80-ns) KrF laser radiation having a fluence of more than 4 J cm ⁻² . The strength of C : F nanocoatings turns out to be comparable with that of titanium and exceeds several hundred times the corresponding characteristics of Teflon F-4. The high transparency of FO indicates a possibility of using it as a cover liquid when modifying titanium surface using beams of various technological lasers.
We proposed a finger-like hardness tester based on the electromechanical impedance of a piezoelectric bimorph cantilever. A Vickers indenter was fabricated to the free end of the bimorph to contact the sample. The contact force was monitored by a strain gauge and the contact area was obtained by tracking the bimorph’s resonance frequency. The bimorph-sample contact system was modeled by the electromechanical equivalent circuit method. Verification experiments on standard hardness samples were conducted and the measured hardness values agreed well with those given by a conventional Vickers hardness tester. Further hardness measurement on a gear wheel showed that the proposed hardness tester is very adaptive and can be used for inner surface testing or in situ testing, where other hardness testers may not be applicable. The proposed hardness tester can be regarded as an improved ultrasonic
hardness tester.
Since in instrumented indentation the contact area is indirectly measured from the contact depth, the natural and unavoidable roughness of real surfaces can induce some errors in determining the contact area and thus in calculating hardness and Young's modulus. To alleviate these possible errors and evaluate mechanical properties more precisely, here a simple contact model that takes into account the surface roughness is proposed. A series of instrumented indentations were made on W and Ni samples whose surface roughness is intentionally controlled, and the results are discussed in terms of the proposed model.
Metallic materials. Instrumented indentation test for hardness and materials parameters
- Bs
- Iso
BS EN ISO 14577: 2015. Metallic materials.
Instrumented indentation test for hardness and
materials parameters.
Автоматизированный контроль параметров композитных изделий с помощью нанотвердомера
- К Кравчук
Кравчук К. et al. Автоматизированный контроль параметров композитных изделий с помощью нанотвердомера "НаноСкан" // НАНОИНДУ-СТРИя. 2016. Vol. 65. № 3. P. 54-58.