Two triazine derivatives, 6-(diethanolamino)−2,4-bi-(sodium sulfanilate-yl)−1,3,5-triazine (STB) and 6-(ethyl xanthate)−2,4-bi-(sodium sulfanilate-yl)−1,3,5-triazine (STC) were synthesized and used as additives in water-glycol base fluid (mass ratio 1:1). Water solubility tests indicated that STB and STC met the solubility prerequisite for a water-soluble additive. The tribological tests by using a four-ball tribometer showed that, STB and STC both improved greatly the P_B value, antiwear and friction-reducing capacities of the base fluid. Based on friction test results and wear scars’ analysis, it was concluded that the differences in tribological performances of STB and STC samples were mainly due to the differences of the sulfur content and the sulfur activity in additives. XPS found that STB-tribofilm mainly contained sulfate, but STC-tribofilm additionally contained sulfide.

Three novel xanthate-containing water-soluble triazine derivatives, 2,4-Di-(N,N-diethanolamine)-6-(ethyl xanthate ester-yl)-1,3,5-triazine (EXT), 2,4-Di-(N,N-diethanolamine)-6-(butyl xanthate ester-yl)-1,3,5-triazine (BXT) and 2,4-Di-(N, N-diethanolamine)-6-(hexyl xanthate ester-yl)-1,3,5-triazine (HXT), were synthesized and used as additives in water-glycol base fluid. It was found that the additive-containing samples had no corrosive effect on the cast iron and copper surface within 2.5 wt% additive. The tribological test results using a four-ball tribometer showed that the three additives greatly improved the P_B value, friction-reducing and antiwear performances of water-glycol. XPS results indicated that the additives had reacted with the contact metal surfaces and formed complex tribofilms composed of iron oxide, iron sulfide and iron sulfate, which may contribute to the reduction of friction coefficient and wear rate of the friction system.