Nonaqueous in-situ synthesis and tribological characteristics of ultra-dispersity-stability ZnS nanoparticles

The oil-soluble zinc naphthenate and isocyanate hyper-dispersion stabilizer were successfully synthesized. The ZnS nanoparticles (n-ZnS) were synthesized in-situ in liquid paraffin containing zinc naphthenate and hyper-dispersion stabilizer. The size, size distribution and conglomeration behavior of n-ZnS in dispersion were observed by the freeze-etching replication transmission electron microscopy technique. Formation and dispersion stability mechanism of n-ZnS were investigated. The tests of normal and high speed centrifuge were used for evaluating the dispersion stability of n-ZnS. Tribological characteristics of the lubricants in the presence and absence of n-ZnS were investigated by the block-on-ring and four-ball tribo-test. The results show that the n-ZnS are grain shape with 40 nm size and single-particle-dispersion properties, which didn't come into being sedimentation through 72 h centrifuge tests and 56 h intermittent high speed centrifuge tests. The n-ZnS Nano-dispersion exhibited antiwear property as well as extreme pressure property. The tribological characteristics of oil samples take a turn for better with n-ZnS content adding in the range of experiment. And the extreme pressure properties are heading for stability when n-ZnS contents of oil samples are weight percent of 0.25%.