Synthesis and characterization of Co-Al-CO3 layered double-metal hydroxides and assessment of their friction performances

In this paper, Co-Al-CO3 layered double-metal hydroxides (CAC-LDHs) were prepared by co-precipitation method and characterized by XRD, FT-IR, TG-DSC, SEM. In addition, their frictional features were evaluated by four-ball friction tester, gear tester and air compressor. The results showed that optimized synthetic conditions of CAC-LDHs were water-ethanol solution media with Co/Al mol ratio of 3:1, crystallization temperature of 120 degrees C and crystallization time of 5 h. The LDHs have perfect crystals with hexagonal lamella structures. Most crystallites have disk diameter of 150-200 nm and thickness of 20 nm. The d-spcing and gallery height of CAC-LDHs were 0.77nm and 0.29nm, respectively. Total specific surface area of the sample is 97 m(2)/g and pore volume is 0.14 cm(3)/g. As a lubricant, CAC-LDHs can significantly reduce friction coefficient (49.1%) and wear of friction pairs. They can also reduce temperature of lubrication oil (7.4-7.7%) and energy consumption of driving motor (4.8-7.0%). Accordingly, CAC-LDHs may broadly be used as lubrication and anti-frictional materials. (C) 2012 Elsevier B.V. All rights reserved.