The Preparation Of Nano Copper Powders And Their Behavior In Lubricating Oil

In this paper,nano-copper powder was prepared by liquid phase reduction method using reducing agent to reduce copper salt.Potassium borohydride?KBH₄?was used as reducing agent,and copper salt was selected from copper sulfate pentahydrate?CuSO₄?.Use potassium hydroxide?KOH?to provide an alkaline environment.Polyvinylpyrrolidone?PVP?,cetyltrimethylammonium bromide?CTAB?and oleic acid are used as dispersants to improve the dispersion stability of the nano copper powder.By changing the amount of reactants added,the impurities in the nano-copper powder were reduced,and the optimum process parameters for preparing small-sized and uniform copper powder were determined.The main conclusions were as follows:1.When the ratio of the amount of the reactants is n?CuSO₄?:n?KBH₄?=2:1,the prepared nano copper powder is pure in composition and does not contain the impurity Cu₂O.When the reaction temperature is gradually increased from 20?to 40?,the particle size of copper powder is gradually reduced;when the reaction temperature is40?,the particle size reaches a minimum of 55 nm;when the reaction temperature is gradually increased from 40?to 60?,the particle size of copper powder is gradually increased.The optimum reaction temperature was determined to be 40?.2.When the initial concentration of Cu²⁺is gradually increased from 0.02mol/L to0.08mol/L,the particle size of copper powder decreases gradually;when the initial concentration of Cu²⁺is 0.08mol/L,the particle size reaches a minimum of 75nm;when the initial concentration of Cu²⁺is gradually increased from 0.08 mol/L to 0.10 mol/L,the particle size of copper powder is gradually increased.The optimum initial concentration of Cu²⁺was determined to be 0.08 mol/L.When the concentration of complexing agent EDTA-2Na is gradually increased from 0.03mol/L to 0.23mol/L,the particle size of copper powder is gradually decreased;when the concentration of EDTA-2Na is 0.23mol/L,the particle size reaches a minimum of 75nm;when the concentration of EDTA-2Na is gradually increased from 0.23 mol/L to 0.43 mol/L,the particle size of copper powder is gradually increased.The optimum concentration of EDTA-2Na was determined to be 0.23 mol/L.When the concentration of KOH is gradually increased from 0.4mol/L to 0.8mol/L,the particle size of copper powder decreases gradually;when the concentration of KOH is 0.8mol/L,the particle size reaches a minimum of 60nm;when the concentration of KOH is gradually increased from 0.8 mol/L to 1.2 mol/L,the particle size of copper powder gradually increases.The optimum concentration of KOH was determined to be 0.8 mol/L.3.When the concentration of PVP is gradually increased from 3×10^-4mol/L to5×10^-4mol/L,the particle size of copper powder is gradually reduced;when the concentration of PVP is 5×10^-4mol/L,the particle size reaches 150nm minimum;when the concentration of PVP is gradually increased from 5×10^-4 mol/L to 7×10^-4 mol/L,the particle size of copper powder is gradually increased.The optimum concentration of PVP was determined to be 5 x 10^-4 mol/L.When the concentration of CTAB is gradually increased from 0.08mol/L to 0.12mol/L,the particle size of copper powder decreases gradually;when the concentration of CTAB is 0.12mol/L,the particle size reaches 75nm minimum;when the concentration of CTAB is gradually increased from 0.12 mol/L to0.16 mol/L,the particle size of copper powder gradually increases.The optimum concentration of CTAB was determined to be 0.12 mol/L.4.When CTAB is used as the dispersant,the nano copper powder particles are in the most stable dispersion state in the basic lubricating oil No.150 when the CTAB concentration is 0.14 mol/L and the ultrasonic dispersion time is 20 min.When oleic acid is used as the dispersing agent,the nano copper powder particles are in the most stable dispersion state in the base lubricating oil of No.150 when the amount of oleic acid added is 20%of the copper powder and the ultrasonic dispersion time is 20 min.5.The diameter of the pure carrier oil spot is 0.83mm.After adding the nano copper powder additive,the diameter of the oil spot of the oil sample decreases with the increase of the additive amount.When the mass fraction of the additive is 0.75%of the carrier oil,the diameter of the oil sample has a minimum of 0.56 mm,which is 32.5%compared to the pure oil sample.At this time,the wear of the steel ball contact surface is minimal and relatively smooth;when the amount of additive added continues to increase,the diameter of the wear spot of the oil sample tends to increase gradually.Therefore,it is determined that the mass fraction of the added nano copper powder accounts for 0.75%of the carrier oil,and the antiwear and antifriction performance is the best.