Proceedings of 41st Danubia-Adria Symposium Advances in Experimental Mechanics (pp. 167-170)
АУТОР(И) / AUTHOR(S): Dragan Džunić 
, Stefan Miletić , Milan Ivković , Slobodan Mitrović
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DOI: 10.46793/41DAS2025.167DZ
УВОД / INTRODUCTION:
The ZA-27 alloy belongs to the group of zinc– aluminium alloys, which are well known for their high strength and wear resistance, good dimensional stability, and relatively low cost compared to other materials with similar technical and operational characteristics. Composites such as ZA-27+Al₂O₃+SiC are increasingly applied in technical and tribo-mechanical systems. These alloys have found wide application in mechanical engineering and transportation, particularly in the automotive industry for brake components, engine parts, and steering systems, as well as in aerospace applications and machine tools, where elements are exposed to increased friction and wear.
By combining ZA-27 with reinforcements such as Al₂O₃ (aluminium oxide) and SiC (silicon carbide), composites with exceptional properties are obtained. Al₂O₃ is used as a reinforcement in composites due to its high hardness and wear resistance. This material significantly improves the mechanical properties of the composite, such as strength, impact resistance, and abrasion resistance. SiC is an extremely hard substance with high heat and wear resistance. When combined with ZA-27, SiC contributes to the composite’s thermal stability and provides additional mechanical durability.
Numerous studies and research papers highlight the advantages of these alloys in practical applications compared to many other materials. The focus of this study is not on comparing ZA-27 alloys with other materials, but rather on examining the ZA-27 alloy with reinforcements, specifically how SiC- and Al₂O₃- based reinforcements influence the coefficient of friction and penetration force during experiments.
The tribological properties of materials are influenced by several factors, including applied load, sliding speed, lubrication conditions and type of lubricant, as well as the surrounding environment in which the experiment is conducted. In the case of composites with reinforcements, the percentage of reinforcement also plays a key role. However, an increased reinforcement content does not necessarily guarantee improved properties; instead, the characteristics also depend on the fabrication method and the degree of homogeneity achieved. A more uniform microstructure ensures consistent performance across the entire surface. Research findings have shown a significant reduction in the coefficient of friction for reinforced materials compared to the base alloy. Optimal results were obtained under a load of 20 N (load range: 20–80 N) and a sliding speed of 1 m/s (speed range: 1–2 m/s), where minimal wear and the lowest coefficient of friction were recorded. Notably, the best results were achieved with a 5% reinforcement content, with variations tested between 1% and 5%.
The fabrication method also significantly affects the properties of such composites. These materials are most commonly produced by either sintering or compo-casting. Increasing the sintering temperature has been found to reduce wear and improve friction resistance, highlighting the potential for application of these materials in demanding industrial environments. The results confirm that high-temperature sintering substantially enhances the tribological properties of the material. These findings may be of great importance for the development of new materials in engineering and manufacturing, where wear resistance is critical.
Several studies hypothesize that the addition of SiC and graphite enhances the wear resistance of composites under dry sliding conditions, since these solid particles can reduce friction and wear compared to unreinforced ZA27 alloy. Experimental results confirm that composites reinforced with SiC and graphite exhibit significantly reduced wear compared to the base ZA27 alloy, thereby supporting the hypothesis regarding improved tribological properties. This analysis highlights the potential of ZA27/SiC/Graphite composites for industrial applications in environments where wear resistance is critical. Another important finding is that composites containing graphite demonstrated much better results than those without, as graphite acted as a solid lubricant.
In addition to dry sliding tests, investigations including lubrication with oil at the contact interface have also been carried out. These results confirm the positive influence of nano-graphite on the tribological performance of ZA27 alloys under lubricated conditions, opening new opportunities for industrial applications.
Furthermore, results have shown that the strength and hardness of aluminium alloys increase with the addition of Al₂O₃, while the wear rate decreases. This emphasizes the role of Al₂O₃ as a reinforcement in aluminium-based composites, which may be highly relevant for the development of more efficient braking systems in the automotive industry.
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ПРОЈЕКАТ / ACKNOWLEDGEMENT:
ЛИТЕРАТУРА / REFERENCES:
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