Laser surface cleaning of carbonaceous deposits on diesel engine piston

Study on the effect of ambient gas on nanostructure formation on metal surfaces during femtosecond laser ablation for fabrication of low-reflective surfaces

https://dr.ntu.edu.sg/bitstream/10220/39760/1/Effect%20of%20processing%20environment%20on%20laser-induced%20darkening%20evolution%20in%20magnesium%20alloy.pdf

Effect of processing environment on laser-induced darkening evolution in magnesium alloy

Mg alloys are ultralight but their structural applications are often limited by their poor wear and corrosion resistance. The research aimed to address the problem by laser-cladding. Cladding with SiC powder onto surface of AZ91D was carried out using Nd:YAG laser. The laser-clad surface was analyzed using the optical microscope, SEM equipped with EDS, and XRD and found to contain SiC and other Si compounds such as Mg2Si and Al3.21Si0.47 as well as much refined α-Mg grains and β-Mg17Al12 intermetallics. The laser-clad surface possesses considerably higher hardness but its corrosion resistance is not improved, indicating that the laser-cladding technique can only be adopted for applications in noncorrosive environments where wear is the predominant problem.

Laser cladding of magnesium alloy az91d with silicon carbide

Surface oxidation of Ti was carried out using KrF excimer laser in the presence of O2. Different colors were obtained by varying the number of laser pulses at the fixed laser fluence. X-ray photoelectron spectroscopy shows that the outmost surface is composed of TiO2 and the inner layer consists of TiO and Ti2O3 as well as TiO2. Fractions of titanium chemical states stabilized at 33% TiO, 63% TiO2, and 2% Ti2O3 with increasing number of laser pulses. The surface roughness tends to increase with number of laser pulses. It is suggested that compositional variation and morphological difference contribute to the laser-induced surface coloration.

H. Y. Zheng

Papers

Study of coloration on excimer laser treated titanium surfaces