Supporting Information Synthesis, Characterization and Tribological Evaluation of SDS stabilized Magnesium-Doped-Zinc Oxide (Zn 0.88 Mg 0. O) Nanoparticles as Efficient Antiwear Lubricant Additives Kalyani, Rashmi B. Rastogi *, D. Kumar Department of Chemistry, Indian Institute of Technology (Banaras Hindu University) Varanasi-005, India Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi-005, India Corresponding Author: Rashmi Bala Rastogi Email: rashmi.apc@iitbhu.ac.in Fax No. +9 5436848 S
S. Experimental details At the end of each test, the wear scar diameters on the each three horizontal balls were measured by the Image Acquisition System (supplied with the tribotester) and their mean values were cited as mean wear scar diameter (MWD) using equation. The coefficient of friction was obtained by the computer programme automatically. S.. Tribological Parameters S... Mean wear scar diameter (MWD) d + d+ d= 3 d3 S... Mean wear volume (MWV) 4 Π d 0 d 4 d Wear volume, V= {( ) ( )} 64 r d d 0 0 3Pr 3 Hertzian diameter, d0 = ( ) 3 4E Where, = + r r r E * v = E v + E Where, E * = Resultant modulus of elasticity v = Poissons ratio r = Radius of steel ball E = E = 06 GPa v = v = 0.3 P = Actual load in Newton on each of the three horizontal balls that is 0.408 times of applied load. S
S..3. Wear rate Overall, running-in and steady-state wear rate have been calculated on the basis of observed mean wear volume data at different time intervals. Mean wear volumes at different times (5, 30, 45, 60, 75 and 90 min.) for each experiment were plotted with time and a linear regression model was fitted on the points including origin to find out overall wear rate. V = mean wear volume l = sliding distance (πr.n) K = wear coefficient H = hardness of steel ball (59-6 HRC) P = applied load (0.408x39N) = S. Instrumentation XRD measurements were conducted on a Bruker D8 Advance diffractometer using Cu Kα radiation at min - scanning rate in the range of 0-80. The morphology of the product was characterized by TEM with an accelerating voltage of 0 kv. The chemical composition of nanoparticles was studied using Energy Dispersive X-Ray Spectroscopy (Oxford Instruments). Morphological features on the worn area of steel balls, lubricated with paraffin oil and its blends with different SZMOs, were examined by SEM with EDX and AFM. After testing the ZMOs nano particles under different test conditions, one of the three lower balls was ultrasonically cleaned in hexane for about 5 min and allowed to dry in the atmosphere. Scanning electron microscope (SEM) images of the wear scar generated on the steel balls were taken using a ZEISS SUPRA 40 electron microscope. The elemental compositions of tribofilm formed on the worn surface of the steel balls were determined by using EDX. Contact mode Atomic Force Microscope (Model No. BT 08, Nanosurf easyscan Basic AFM, Switzerland) was used to investigate roughness of the worn surfaces with Si 3 N 4 S3
cantilever (Nanosensor, CONTR type) having spring constant of ~0.Nm - and tip radius more than 0 nm. Figure S. Energy dispersive X-ray spectrum showing constituents and chemical composition of ZMO nanoparticles Figure S. Variation of mean wear scar diameter with time in paraffin oil containing SZMOs nanoparticles at 39N applied load S4
Figure S3. Variation of mean wear volume with time (h) in paraffin oil containing SZMOs nanoparticles at 39N applied load S5
Figure S4. Determination of running-in wear rate by varying mean wear volume with time (h) for paraffin oil containing SZMOs nanoparticles at 39N applied load Figure S5. Determination of steady-state wear rate by varying mean wear volume with time (h) for paraffin oil containing SZMOs nanoparticles at 39N applied load S6
Table S. Wear rates of paraffin oil in absence and presence of SZMOs nanoparticles as antiwear additives at 39N applied load for 90 min test duration S.N. Additives Wear Rate (0-4 x mm 3 /h) Running-in Steady-state. SZMO 5.60.00. SZMO- 30.00 3.00 3. SZMO- 4.60 7.60 4. Paraffin oil 69.99 38.88 S7
Figure S6. SEM micrographs of the worn steel surface lubricated with different nanoparticles in paraffin oil for 30 min test duration at 490 N applied load: (a,b). Paraffin oil, (c,d).szmo and (e,f).szmo- nanoparticles S8
Figure S7. D and3d-afm images of the worn steel surface lubricated with different additives in paraffin oil for 30 min test duration at 490N applied load: (a,b). Paraffin oil, (c,d). SZMO and (e,f). SZMO- nanoparticles S9
Figure S8. Elemental mapping of the various elements on worn steel surface lubricated with SZMO nanoparticles for 60 min test duration at 39N applied load; (a). C, (b). O, (c). Mg, (d).zn and (e). Fe S0
Figure S9. EDX analysis data of the worn steel surface lubricated with paraffin oil in presence of different nanoparticles for 30 min test duration at 490N applied load: (a). SZMO and (b). SZMO- S