IMPROVING THE TRIBOLOGICAL PROPERTIES OF THE LUBRICANT USING ZnS NANOPARTICLES AS LUBRICANT ADDITIVES

One of the main causes of mechanical parts failure is wear and friction between bearing surfaces. There is a lot of interest in the search for novel additives with excellent tribological characteristics. During this paper, the friction and wear of steel surfaces are discussed. zinc sulphide nano particles dispersing paraffin oil were used as lubricating substance. ZnS addition is aimed to reduce the impact friction between metal elements, on friction coefficient and wear of steel test specimens. The experiment was conducted using a cross-pin tester. The device consists, mainly, of rotating and stationary pins of 18 mm diameter and 130 mm long. (10, 15 and 20 N) normal loads are applied by means of weights attached to a loading lever. The rotating specimens are oiled with several percentage of zinc sulphide nano-additives (0, 0.2, 0.4, 0.6, 0.8, 1.0 wt. %) dispersing in paraffin base oil before the test and further oil is carried out every 30 sec. during the test. The test time is 5 min. The friction force is measured via a digital screen that connects to the load cell. Under an optical microscope, the scar's diameter is measured to indicate wear, and the coefficient of friction is computed by dividing the friction force by the normal load. Experiments were carried out at 25 °C using parrafin based oil dispersed by the solid additives of zinc sulphide nano particles. Experimental results show that 0.4 wt. % Zinc sulphide nano filler added to paraffin oil gives the best anti-friction and wear resistance performance.