Effects of silicon content and test conditions on the dry wear behaviour of Zn–30Al–3Cu–(0–5)Si Alloys

Dry sliding wear performance of Zn-30Al-3Cu-(0-5)Si alloys was studied using a block-on-disc type test apparatus. Their microstructure consisted of β dendrites, α, η, and ϵ (CuZn4) phases, and silicon particles. Hardness and tensile strength of the alloys increased with silicon content but above 1% Si the trend reversed for the tensile strength. Total percent elongation, impact energy, compressive strength, and quality index of the alloys decreased with silicon content. However, the friction coefficient and wear volume showed different changes with silicon content, sliding distance, contact pressure, and sliding velocity. Worn surface examinations indicated that the wear of these alloys occurs by both abrasion and adhesion. Non-linear regression analysis showed that the friction coefficient and wear volume of the alloys can be calculated in terms of silicon content and either sliding distance or contact pressure and sliding velocity using the empirical equations developed in this work. Zn-30Al-3Cu-0.5Si alloy exhibited the highest quality index and wear resistance among the alloys tested. It was concluded that the hardness and tensile strength of the alloys containing hard and brittle phases have opposite effects on their dry wear behaviour. The wear volume of such alloys decreases with increasing hardness but increases with tensile strength.