Nanofillers for lubricants in mechanical applications: improved performances in real systems and technological impact

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Winfred Craig
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1 Nanofillers for lubricants in mechanical applications: improved performances in real systems and technological impact Eng. Lorenzo Calabri, Ph. D. COO TEC STAR: FULL partner in nanotecnology Complete problem solving service: from the analysis of the state of the art to the industrial supply of nanoparticles

2 Summary Tec Star Srl: new engineered nanomaterials company lubricants: how they work dispersion and stability liquid and grease nanocomposite lubricants: tribological properties Examples of applications

MMNCs OIL LUBRICANT CHARACTERIZATION SYNTHESIS SEM cross section of aluminum alloy MMNC.

3 POLYMERS Tec Star Srl PAINTS: COATINGS: SEM cross section picture of nanocomposite PUR. Antibacterial Polypropylene. Electrodeposited Nickel + nano. MMNCs OIL LUBRICANT CHARACTERIZATION SYNTHESIS SEM cross section of aluminum alloy MMNC. Nanofilled Lubricant Oil SEM/TEM nanoparticle (ZrO2) September 2015 Rome / characterization NanoItaly 2015 bimetallic nanoparticles Chemical Synthesis

4 Tec Star Characterization Lab TEC STAR S.r.l. SERVICES - NANOPARTICLES & NANOCOMPOSITES CHARACTERIZATION: Full characterization of nanopowders and nanoparticles (quality control analysis - production and supply): Shape and morphology (Hi-res FE-SEM or TEM) Average size (APS) (FE-SEM, TEM or XRD) Main crystal phases (XRD) Chemical surface composition (XPS) Size, stats distribution and Z potential for liquid dispersion (DLS) Mechanical test (tensile, impact, hardness, etc.) Tribo test (ball/pin-on-disc, block-on-ring, fretting) SERVICES - NANOCOMPOSITES PREPARATION: Chemical synthesis and functionalization of nanoparticles & nanocomposites formulation: High velocity homogenizer (VELP OV5) Horn Sonicator 750W (SONIX VCX750) Glove box for safety handling Centrifuge (Thermo SL16) Chemical Hood Zirconium dioxide ZrO2

5 lubricant: how they work BOUNDARY LUBRICATION regime is critical for wear and friction. To work in this condition, people add to lubricants chemical EP additives. Tipical additives are based on Chlorine, Sulfur, Phosphorus, Zinc, etc. Main problems using these kind of chemical additives are due to chemical incompatibility, temperature effect, pollution.

insensitive to temperature small dimensions: allow them to easly enter the contact area

6 lubricant: how they work Nanoparticles as additives for lubricants are: oxides and/or sulfides spherical or onion like structure functionalized or not chemically inert insensitive to temperature small dimensions: allow them to easly enter the contact area low concentration sheared transfer layers arranged on the surface for boundary layer lubrication

7 lubricant: dispersion and stability Silane functionalization S1 - Silane n 1 Long pol. chain S2 - Silane n 2 Mid pol. chain S3 - Silane n 3 Short pol. chain Uncoated DCG S1-coated DCG S2-coated DCG S3-coated DCG Average Agglomerate size (µm 2 ) Sedimentation time (days) 3 8 >14 4 DCG = dichalcogenide structure

8 lubricant: tribological properties DCG = dichalcogenide structure WR=V/(L D)

lubricant: tribological properties of mineral oil Tribological test: Wear Rate (WR) vs different kinds of nanoparticles: Room Temperature Vertical Load = 500N Rotational Speed = 200 rpm Time = 30 min.

9 lubricant: tribological properties of mineral oil Tribological test: Wear Rate (WR) vs different kinds of nanoparticles: Room Temperature Vertical Load = 500N Rotational Speed = 200 rpm Time = 30 min. Block Material = 39NiCrMo5 Mineral Oil ISO 320 (M320) Nanoparticles Concentration = 0.05 wt.% Kind of Nanoparticles = variable 1. Best results = DCG2 2. Others kinds of nanofiller increase the WR 3. Main problem = Nanoparticles dispersion and stability 4. DCG2 is more stable with respect to the other ones

lubricant: tribological properties of mineral oil Tribological test: WR vs Concentration of Nanoparticles (NPs) : Room Temperature Vertical Load = 500N Rotational Speed = 200 rpm Time = 30 min.

10 lubricant: tribological properties of mineral oil Tribological test: WR vs Concentration of Nanoparticles (NPs) : Room Temperature Vertical Load = 500N Rotational Speed = 200 rpm Time = 30 min. Block Material = 39NiCrMo5 Mineral Oil ISO 320 (M320) NPs concentration = variable NPs = DCG2 WR doesn t change with respect to the concentration of DCG2 NPs. The decrease of WR in roughly 35%.

11 lubricant: tribological properties of synthetic oil Tribological test: WR vs NPs concentration: Room Temperature Vertical Load = 700N Rotational Speed = 870 rpm Time = 30 min. Block Material = CuSn12 Synthetic Oil PAG ISO320 (P320) NPs concentration = variable NPs = DCG2 WR decrease vs concentration of NPs. WR decrease = roughly 80%.

12 lubricant: tribological properties of synthetic oil Tribological test: WR vs Vertical Load: Romm Temperature Vertical Load = variable (low 470N, medium 700N, high 950N) Rotational Speed = 870 rpm Time = 30 min. Block Material = CuSn12 Synthetic Oil PAG ISO320 (P320) NPs concentration = 1 wt.% NPs = DCG2 NPs decrease the WR with respect oil without NPs.

13 lubricant: tribological properties of grease Weld Load (WL) measures were performed with a four-ball apparatus, according to ASTM D The Weld Load is in kilograms and it represents the lowest applied load in kilograms force at which the rotating ball seizes and then welds to the three stationary balls. The four-ball Wear Rate (WR) test (ASTM D2266) is run for 60 min at 1,200 rpm with a load of 40 kg.

14 lubricant: example of applications Bearing Comparison of wear and tear of the inner bearing rings. Wear and tear of orbits is about the same even though the bearing lubricated with grease with the additive ran about a two fold number of hours. Grease Nanoadditive has a positive impact on the bearing lubricity which led to: 1. Bearing friction reduction 2. Reduction in the operating temperature of bearings during the test 3. Significant improvement of the bearing service time (in about 100%), 4. Increasing of bearing dynamic load by about 30%.

15 lubricant: example of applications Worm gearbox Yield and Temperature vs Synthetic Oil: normal and nanocomposite

16 lubricant: example of applications WORK IN PROGRESS Drawing Metal We compare Chlorinated oil and Nanocomposite oil Result: the speed of work increased by 15-20%

17 Contacts TEC STAR S.r.l. Eng. Lorenzo Calabri, Ph. D. TEC STAR Srl Viale Europa, Campogalliano (MO) - Italy Tel (+39) Fax (+39)

FALEX Four-Ball Extreme Pressure Test Machine

FALEX Four-Ball Extreme Pressure Test Machine The Four-Ball EP Test measures a lubricant s extreme pressure properties under High Hertzian contact in pure sliding, or pure rolling, motion. The test is