Savaşkan, Temel; Hekimoğlu, Ali Paşa; Azaklı, Zeki

The effect of isothermal exposure at temperatures from 100°C to 250°C for 8 hours on the structure, mechanical and tribological properties of the Zn – 40% Al – 2% Cu – 2% Si alloy produced by chill casting is studied. The isothermal treatment eliminates dendritic segregation yielding a coarse-grained polyhedral structure containing an α-solid solution with fine inclusions of silicon and zinc-rich phase. Increase in the temperature of the isothermal exposure leads to decrease in the hardness and strength and increase in the ductility, in the coefficient of friction and in the wear magnitude while reducing the average roughness of the alloy surface.

Hekimoğlu, Ali Paşa; Savaşkan, Temel; Azakli, Zeki

An attempt was made to correlate mechanical (hardness and ultimate tensile strength) and tribological properties (friction coefficient, working temperature, wear volume and average surface roughness) of Zn-40Al-2Cu-2Si alloy which was prepared by permanent mold casting. The tribological properties of the alloy were determined using a block-on-cylinder type wear test machine. The relationships between the mechanical and tribological properties of the alloy determined by linear regression analysis were observed to be expressed by linear or straight-line equations. The correlation coefficients of these relationships were found to be between 0.94 and 0.99. These linear equations indicate that the friction coefficient and the wear volume of this alloy can be calculated in terms of either its hardness or tensile strength under the given working conditions. These linear relationships also showed that as the hardness and the tensile strength of the alloy increase the friction coefficient, working temperature, and wear volume of it decrease but its average surface roughness increases. These observations were explained in terms of the microstructure and mechanical properties of the alloy, adhesion theory of friction and the Archard wear law. The equations obtained by this correlation can also be used for the selection of Zn-40Al-based alloys for bearing applications.