Strategies for High-Value Utilization of Magnesium Resources from Salt Lakes: Synthesis of Amine-Intercalated Magnesium Phosphates as Innovative Lubricants

In the present study, we developed organic amine-intercalated magnesium phosphates as new types of lubricants. Long-chain organic amine-intercalated magnesium phosphates, i.e., dodecylamine intercalated magnesium phosphate (MgP-12N), octadecylamine intercalated magnesium phosphate (MgP-18N), and 1,12-dodecanediamine intercalated magnesium phosphate (MgP-1,12N2), were prepared for the first time by mixed solvothermal synthesis. When added to lubricating oil, these samples exhibited good antifriction and antiwear properties and extreme pressure performance. Adding 1.0 wt % MgP-18N to N4010 base oil significantly increased the pressure load value according to evaluations using an Optimol SRV-V oscillating reciprocating tester from 400 N (base oil) to 1400 N. In addition, this sample exhibited a low friction coefficient (0.107) and volume wear (2.86 × 10^-4 mm³) under high operating loads. Microscopic analysis of the rubbing surfaces confirmed that lubricating films mainly composed of amine-intercalated magnesium phosphates formed on the worn surface during the friction process. Moreover, the amine-intercalated magnesium phosphate samples could be dispersed in the lubricating oil for a long time under the action of the dispersant oleylamine, indicating that these materials have broad application prospects as lubrications.