Use of carbon black powder for surface treatment of stainless steel substrates via a low-cost CO2 laser

Nowadays, AISI 304 stainless steel plays a crucial role in industry. However, stainless steel exhibits limited wear resistance as it is used in parts with relative motion. Laser treatment emerges as a promising approach to improve its superficial properties. Using a laser as a heat source presents unique properties for heating surfaces, as the first atomic layers of the material absorb the radiation from the laser beam. In this study, we used a low-cost 100 W CO2 laser with carbon black powder to treat the surface of AISI 304 steels. In addition, the reflectance of irradiation on steel is 90%. We used carbon black powder as a photo-absorbing material for radiation to overcome this obstacle. The characterization included field emission gun–scanning electron microscopy, energy dispersive x ray, microhardness, and pin-on reciprocation tribometer. The results showed a significant increase in surface hardness after laser treatment compared to the untreated substrate at a magnitude of 3.8 times. Elemental mapping analysis revealed carbon's presence on the substrate's surface. In addition to increasing surface hardness, we observed a decrease in the friction coefficient of the laser-treated samples compared to the reference substrate. Finally, it could be concluded that carbon black powder had a triple function; it acted as a photo-absorbent material, a carbon source to increase surface hardness, and a solid lubricant. These results show the predictions of using a low-cost CO2 laser with carbon black powder as an efficient, versatile, and fast alternative.