TY  - JOUR
A1  - Wang, Hao
A1  - Nett, Ralf
A1  - Gurevich, Evgeny L
A1  - Ostendorf, Andreas
T1  - The Effect of Laser Nitriding on Surface Characteristics and Wear Resistance of NiTi Alloy with Low Power Fiber Laser
JF  - Applied Sciences
N2  - The laser nitriding was performed in nitrogen gas at room temperature (20 °C) and low temperature (−190 °C) by a low power fiber laser to modify the wear and abrasion resistance of NiTi alloy. The surface roughness and element composition were analyzed by roughness device and energy-dispersive X-ray spectroscopy respectively. The results of roughness show that laser treatment can change the surface roughness due to the laser remelting. The effect of laser nitriding on the microhardness, friction coefficient, and worn scars of NiTi alloy was also studied, which shows that the microhardness of the NiTi alloy increases after laser nitriding. The optical microscope and scanning electron microscope were used to characterize the surface of NiTi alloy after wear testing to observe the microstructure of worn scars. The results show that the laser nitriding with different parameters can induce a nitride layer with different thicknesses and the higher energy deposition is the key factor for the formation of the nitride layer, which can decrease the friction coefficient and reduce wear loss during the application of NiTi alloy. The improvement of wear resistance can be attributed to the hard nitriding layer.
KW  - laser nitriding; wear resistance; NiTi alloy; roughness; microhardness
Y1  - 2021
U6  - http://dx.doi.org/10.3390/app11020515
VL  - 11
IS  - 2
SP  - 515
ER  - 
TY  - JOUR
A1  - Maragkaki, Stella
A1  - Skaradzinski, Christian A
A1  - Nett, Ralf
A1  - Gurevich, Evgeny L
T1  - Influence of defects on structural colours generated by laser-induced ripples
JF  - Scientific Reports
N2  - The colourisation of metallic surface which appears due to periodic surface patterns induced by ultrashort laser pulses is studied. Ripples due to the sub-micrometer size of their period act as a diffraction grating, generating structural colours. Carefully chosen strategy of the laser spot scanning allows us to mimic the nanostructures responsible for structural colours of some flowers on the metal substrate. We investigate the correlation between the colourising effects and the artificially-induced defects in the ripples structure and show that these defects can make the colours observable in a larger range of viewing angles. Further we address the influence of the processing parameters on the spectral profile of the reflected light.
Y1  - 2020
U6  - http://dx.doi.org/10.1038/s41598-019-56638-x
VL  - 10
IS  - 1
SP  - 53
EP  - 53
ER  -