Friction and wear behavior of nodular cast iron modified by a laser micro-precision treatment sliding against steel under the lubrication of liquid paraffin containing various additives

Nodular cast iron was modified by means of a laser micro-precision treatment. The surface roughness of the treated sample was determined with a profilometer. The friction and wear behavior of the modified specimens sliding against SAE-52100 steel under the lubrication of liquid paraffin (LP) containing various anti-wear and extreme pressure additives was investigated on an Optimol SRV oscillating friction and wear tester. The morphologies and elements distribution of the worn surfaces were observed with a scanning electron microscope and an energy dispersive X-ray analyzer, in an attempt to reveal the wear mechanisms of the surface-modified cast iron. The phase composition of the laser treated nodular cast iron was examined by means of X-ray diffraction. As the results, the friction coefficients for the laser treated cast iron are slightly higher than that for the untreated one. The wear volume loss of the treated cast iron specimen sliding against SAE-52100 steel under lubrication of LP containing various additives is only about 5-10% of that of the untreated one. The nodular cast iron specimens after laser surface modification show good surface shape and high rigidity. The substantial increase in the wear-resistance of the cast iron after laser treatment can be attributed to a significant increase in the surface hardness of the laser-modified layers and to the friction-reducing and wear-resistant action of the extreme pressure and anti-wear additives.