Abstract This research investigates the influence of graphite's granulometry on the dry sliding behavior of a copper-free friction material against pearlitic cast iron. Samples were designed and fabricated using three different types of commercial natural graphite. A sample without graphite was also considered as a reference. Tests were carried out with a pin-on-disc tribometer at room temperature (RT), at 400 °C, and at RT after the high temperature tests. The results show that both the shape and size of the graphite particles influence the coefficient of friction and the specific wear rate. The friction material featuring a lower particle size and equiaxed grains of natural graphite exhibits a better behavior, as compared to coarser graphite with plate-like grains. The results were obtained comparing specific characteristics (i.e., morphology and chemical composition) of the friction layers formed on each friction material under the different testing conditions.

中文翻译：

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一种含不同类型天然石墨的无铜摩擦材料的干滑动行为的销盘式研究

摘要 本研究调查了石墨粒度对无铜摩擦材料与珠光体铸铁干滑动行为的影响。样品是使用三种不同类型的商业天然石墨设计和制造的。不含石墨的样品也被视为参考。使用针盘式摩擦计在室温 (RT)、400 °C 和高温测试后的 RT 下进行测试。结果表明，石墨颗粒的形状和尺寸都会影响摩擦系数和比磨损率。与具有板状颗粒的较粗石墨相比，具有较小粒径和等轴颗粒天然石墨的摩擦材料表现出更好的性能。结果是通过比较特定特征（即，