Research On Anti-Wear Properties Of Aluminum Rolling Oil And Characterization On Wear Generation

Cold-rolling lubrication decided the dimensional accuracy and surficial quality of products.The traditional rolling oil was based on mineral oil and contained some lubricating additives.The tribological properties of additives played a leading role on cold lubrication process,which were affected by base-oil molecule structure,but theoretical research on their compatibility was lacking.Wear generation was the key factor that restricted the improvement of the rolled surface quality,which was of great value to explore the its generation mechanism and influence on surface quality.Therefore,this paper studied the tribological behavior of base oil,discussed its compatibility with additives,explained formation mechanism and influence of wear generation,and revealed the influence of additives on rolled surface corrosion:Quantum chemical(QC)calculations showed that mineral oil molecules had a symmetrical distribution of frontier orbitals,adsorbing in a parallel way.As for CTL,the lowest unoccupied orbital distributed at the end of carbon chain,and the highest occupied orbital distributed at the whole carbon chain.The molecules could adsorb in any configuration.The friction coefficient(FC)of mineral oil and CTL on steel-aluminum contact decreased with the load and velocity increase,but the former changed more sensitively.The maximum non-seizure load of CTL(PB=88 N)was lower than that of mineral oil(PB=98 N).CTL showed higher synergism with dodecanol(DDL)and dibutyl phosphite(DBPI).When DDL content was 2 wt.%,PB value of CTL was 304 N,and 245 N for mineral oil.The maximum PB of the CTL containing DBPI was 1050 N,and 981 N for mineral oil based.Coumarin was an effective lubricant,the average friction coefficient and wear scar diameter was reduced by 20.0%and 11.9%when its content was 0.7 wt.%.Wear mechanism was dominated by abrasive wear,adhesion wear and fatigue wear under steel-aluminum contact without lubrication.The adhesion wear was inhibited under the base oil lubrication.In cases of CTL lubrication,the modal diameter of nano-scale wear generation was 307 nm,smaller than that of mineral oil(332 nm).The modal diameter and average diameter of micro-scale wear generation in CTL were 11.2 μm and 15.3 μm,higher than those in mineral oil by 28.7%and 31.9%,respectively.Wear generation promoted the wetting of rollingoil on metal surface,conforming to the Cassie-Baxter model.The thermal gravity curves of base-oil containing wear generation had a "double peak" at the hightemperature,and the termination volatilization temperature increased by 34.4%.DBPI resulted in wear scar indented along the movement direction,and worn morphology developed from sunken to convex structure.Abnormal wear was attributed to the DBPI reactivity,wear generation structure,and the backflow of rolling oil,and its occurrence appeared at concentration higher than 0.2 wt.%.Wear generation had a "capsule" structure with an amorphous shell composed of FePO4,Fe3(PO4)2,Fe[DBPI]2,Fe[DBPI]3,dibutyl phosphate and base oil,and a metallic core.Two proposed indexes ε=1/3∑i=1 3 Xi-WSD/WSD and ψ=1/3∑i=1 3 Y’i/Yi described the severity of abnormal wear in X and Y directions.ε was positive to DBPI concentration and time,while φ was positive to DBPI concentration but had no correlation with time.Cold-rolling tests showed that aluminum rolling oil prepared with different base oil had great lubrication properties,by which the final rolling thickness decreases 3.8%and 7.3%,and roughness decreases 22.0%and 30.5%.Theoretical studies revealed that solvation(gas,water,oil)had no significant effect on the reactive site distribution of different configurations of thiazole derivatives(BODTA),but had a great effect on their global reactivity.BODTA molecules in the horizontal configuration were more active than that in the vertical configuration.BODTA changed from vertical to horizontal configuration when adsorption occurred.BODTA had an inhibition effect at low concentrations,but high content inhibited aluminum passivation.The adsorption activity of coumarin in the water phase was higher than that in gas,and coumarin adsorbed in a parallel manner by accepting electrons,and the optimum inhibition efficiency was 89.6%.