Improving the Absorption Efficiency in CO2 Laser Melting of Aluminum Alloy by Coating the Transparent Film

A transparent absorbent for a laser, perhydropolysilazane (PHPS) films were prepared on an A 1100 aluminum alloy using a dip-coating technique with a PHPS-xylen solution. After dip-coating, the films were dried at 423K for 1.8ks. PHPS films became transparent, and the FTIR spectra of the films showed a absorption peak at the wavelength of a CO2 laser due to Si-N bond. Using a CO2 laser with an output of 1kW, 0.12mm depth of molten zone was obtained for the PHPS film coated samples. The melted zone was not observed for untreated samples using a laser output of 3kW. Film thickness with sufficient absorbability was about 1μm.