Color erasing by ultrafast and nanosecond pulsed laser on titanium

Abstract

In this work, we used 1064 nm nanosecond pulsed laser irradiating titanium surface to obtain different colors with a large variation in total color difference (ΔE*) and systematized the color gamut on titanium. A hand-held colorimeter and the CIEL*a*b* color difference formula were used to quantitatively evaluate the influences of process parameters on the color changes of titanium surfaces. Moreover, a method was reported in this paper to erase selectively the colored areas by changing the processing atmosphere. We compared the erasing effects between ultrafast pulsed laser and nanosecond pulsed laser, and found that ultrafast pulsed laser has higher quality erasure on the colored surface. The results showed that more than 90% O element of colored areas were erased and Ti element increased quickly. The ΔE* between erased areas and bare materials is less than 7, and the reflectance spectra of erased areas is similar to the untreated areas. Furthermore, the wettability of erased fields was changed and the contact angle (CA) was <10°, which indicates the surface shows superhydrophilicity in air.