The effect of ceo₂-doped box boriding process on the structural and tribological CeO2 of AISI 316L stainless steel

AISI 316L stainless steel, which exhibits high mechanical strength due to its strong metallic bonding structure, shows limited surface performance because of its low hardness and insufficient wear resistance. Moreover, exposure to severe corrosive environments significiantly reduces material's corrosion resistance. Among the surface modification methods, developed to carried out through the diffusion of boron atoms into the material surface at high temperatures and significiantly improves surface properties such as hardness, wear resistance, and corrosion resistance. In this thesis study, powder-pack boriding was applied to AISI 316L alloy, which is widely used in the aerospace, marine, automotive, and biomedical, using commercial Ekabor 2 mixtures and boriding mixtures containing different proportions of cerium oxide (CeO₂). The experiments were conducted at temperatures of 850°C, 900°C and 950°C for a duration of four hours. The phase structure and morphology of the generated layers were examined using XRD and SEM analyses, respectively; additionally, microhardness and wear tests were carried out on both untreated and treated samples. While XRD analyses revealed that the addition of 2% CeO₂ promoted the formation of the Fe₂B phase, the highest wear resistance was determined to be achieved in the 2% CeO₂-added sample boronized at 950°C. This sample increased wear resistnce by 32 times compared to the untreated sample and by 3,4 times compared to the boride layer without additives. In contrast, 4% and 6% CeO₂ additions impaired the integrity of the coating layer, adversely affecting. Based on the obtained results, the optimum amount of nano CeO₂ ratio to be added to the boriding mixture was determined as 2%.