Microhardness and wear behaviour of polycrystalline diamond after warm laser shock processing with and without coating

Pacella, Manuela, Jasmine St. John, Marah Grace, Dolatabadi, Nader and Badiee, Amir (2019) Microhardness and wear behaviour of polycrystalline diamond after warm laser shock processing with and without coating. International Journal of Refractory Metals and Hard Materials, 82 . pp. 215-226. ISSN 0263-4368

Full content URL: https://doi.org/10.1016/j.ijrmhm.2019.04.014

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Abstract

Cutting tools made of ultra-hard materials such as polycrystalline diamonds offer superior wear resistance in precision machining of Aluminium alloys. However, the wear properties of these materials are dependent on their microstructural characteristics such as grain size and binder percentage. In this context, the present paper evaluates the effects of two low-energy fibre laser processes (nanosecond pulse duration) on microstructural changes of polycrystalline diamond composites and consequently investigates wear and friction characteristics and micro hardness properties. Pockets were first achieved using a single mode SPI pulsed fibre laser (1064 nm wavelength) inducing both laser shock processing (LSP) and laser peening without coating (LPwC) and characterised using a combination of scanning electron microscopy (SEM), white light interferometry, energy dispersive X-Ray (EDX) and micro hardness analyses. The as-received and processed materials were tested on a pin-on-disc for the evaluation of their wear performance. An analytical model based on the asperities of pin and disc after wear test is proposed to predict the trend of wear performance of different laser-processed materials. LSP with vinyl and quartz at a scanning speed of 500 mm s−1 achieved a micro-hardness of 110 GPa at a depth of 632 nm. LPwC at 0.8 GW cm−2 produced hybrid microstructures which share characteristics of laser shock processing and selective laser melted structures. For laser feed speed in the region of 1000 mm s−1, micro-indentation tests revealed an improvement of hardness from 70 GPa to 95 GPa at a depth of 670 nm for LPwC. Tribotest revealed enhanced wear performance for all laser-processed pins and reduced coefficient of friction also validated by increased material removal rate when compared to the as-received material. To the best of authors' knowledge, it is reported for the first time that an improvement of wear performance can be achieved on polycrystalline diamond through LSP and LPwC.

Keywords:Laser shock peening, Laser peening without coating, Polycrystalline diamond, Microstructural modification, Micro hardness, Wear properties
Subjects:H Engineering > H700 Production and Manufacturing Engineering
H Engineering > H300 Mechanical Engineering
Divisions:College of Science > School of Engineering
ID Code:38257
Deposited On:05 Nov 2019 10:18

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