Tribological behavior of zirconium phosphate‐1,4‐dimethylpiperazine compound as lubricant additives

Zirconium phosphate compound, [C 6 H 16 N 2 ] 0.5 Zr‐(H 0.5 PO 4 ) 2 •H 2 O designated as ZrPO 4 ‐DES8 have been synthesised hydrothermally in the presence of 1,4‐dimethylpiperazine (DMP). In this study, small (0.5‐0.8 μm) and large (8‐10 μm) ZrPO 4 ‐DES8 particles were obtained by varying the amount of H 3 PO 4 in the HF ‐ ZrO 2 ‐P 2 O 5 ‐DMP‐H 2 O hydrothermal system. The tribological properties of ZrPO 4 ‐DES8 particles as additives in lithium grease were evaluated by using a ball‐on‐disk reciprocating tribometer under different concentrations, loads, and frequencies. The results illustrated that ZrPO 4 ‐DES8 particles improved the lubricating performance of grease substantially. The small‐sized particles exhibited better and more stable friction reduction and anti‐wear performance than larger ones during sliding. The characterisation of a possible wear mechanism was given by observing the worn surface under a three‐dimensional optical profiler, a scanning electron microscope and energy dispersive X‐ray analysis. The simple synthetic method and superior tribological properties make the ZrPO 4 ‐DES8 become a choice for lubricant additives.