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•The change of CA over time on laser micro-structured surfaces is investigated.•The relationship between CA and chemistry was discussed by model description.•The coefficients in the ...model were obtained by multiple regression analysis.•The reason for CA becoming high is related to the carbon and oxygen-(metal oxide).•The reason for CA keeping low is related to the effect of oxygen-(layer).
In recent years, control of the wettability of metal surfaces by laser micro-structuring has attracted much attention. In particular, for applying to industrial applications, long-term stability of wettability is required for metal surfaces by laser micro-structuring, since the wettability of the surface changes over time. In this study, the influences of various chemical components on contact angle (CA) changes over time were quantitatively investigated using a model based on multiple regression analysis. For this purpose, this study investigated the CA and chemical components of laser micro-structured stainless steel 304 surfaces 40 and 80 days after laser micro-structuring. In the end, the reason for the CA becoming high was related to the carbon-C–C(C–H), carbon-(polar), and oxygen-(metal oxide). Moreover, the reason for the CA keeping low for a long time was related to the effect of oxygen-(layer).
Considering the relatively poor surface and subsurface quality of workpieces that are ground by coarse-grained grinding wheels, the nanosecond ultraviolet laser micro-structuring of coarse-grained ...diamond grinding wheels and the grinding performance of micro-structured grinding wheels were investigated in this study. In addition, the effect of two processing sequences on the topographical characteristics of the grooves and the effect of the groove angle (
α
) on the surface roughness (
R
a
) of the ground workpiece were explored. Furthermore, the surface quality of workpieces that were ground by micro-structured (V-shaped and W-shaped patterns) and non-structured diamond grinding wheels and the grinding ratio (
G
) of the grinding wheels were comparatively analyzed. The results demonstrate the following: Compared with the grinding wheel that was subjected to micro-structuring followed by sharpening, the surface of the grinding wheel that was subjected to sharpening followed by micro-structuring had a more integral groove structure. Neither an overly large
α
nor an overly small
α
was favorable for improving the surface quality of the workpiece that was ground by a micro-structured grinding wheel. When
α
= 60°, the minimum
R
a
of the workpiece was attained. The
R
a
of the workpieces that were ground by the grinding wheel with a V-shaped pattern (grinding wheel A) was 17–31% less than the
R
a
of the workpieces that were ground by the non-structured grinding wheel (grinding wheel C). The
R
a
of the workpieces that were ground by the grinding wheel with a W-shaped pattern (grinding wheel B) was 32–41% less than the
R
a
of the workpieces that were ground by grinding wheel C. The grinding performance of the micro-structured grinding wheels was related not only to the geometric parameters of the grooves but also to the micro-structure pattern. The W-shaped pattern was superior to the V-shaped pattern in terms of cooling and chip removal. Grinding wheel A and grinding wheel B had similar abrasion resistance, which were 26% less and 23% less than the abrasion resistance of grinding wheel C, respectively.
Accompanying with the extensive applications of micro-structured surfaces on hard and brittle material in MEMS and NEMS sensors, optical elements, electronic devices and medical products, efficiently ...fabricating of these surface has gradually become the focus of manufacturing community. Basing on precision grinding with conditioned and laser micro-structured coarse-grained diamond grinding wheel, a novel high efficiency technique for micro-structured surfaces on hard and brittle material, such as silicon carbide, was developed in this paper. Firstly, the maximum undeformed chip thickness for conditioned coarse-grained wheel and the ductile grinding of silicon carbide was theoretically and experimentally studied. Silicon carbide surface formed mainly in ductile regime was successfully achieved. And then, the strategy for micro-structuring the conditioned wheel with designed micro-structure geometry, sharp edge and small inclination angle side-wall was investigated. Finally, the linear and square micro-structured surfaces with high form accuracy and ultra-precision surface roughness were successfully and efficiently fabricated on silicon carbide by the technique developed in this paper.
Laser-induced plasmas are investigated during laser micro structuring of a C 75 steel alloy using laser bursts that consist of nanosecond laser pulses under atmospheric pressure. The influence of the ...laser burst mode — single and collinear double pulses — on plasma dynamics and ablation efficiency is investigated for burst energies in the millijoule regime. Electron density and excitation temperatures measured as a function of time. The results are compared with published data looking for changes of the plasma parameters scaling with the burst energy over two orders of magnitude. For collinear double pulses at burst energies of 1–2 mJ an increase of the ablation rate by a factor of three to four compared to single pulses was observed.
