LUBRICANTS • Lubricants were in use before the invention of wheel. • Building block of 95% of today’s lubricants is mineral oil. • Straight run MO not satisfactory for operating under arduous conditions. • Modern Lubricant is highly refined HC base stock+chemical additives.
APPLICATION % Engine 55 Industrial 27 Process 9 Grease 5 Automotive Transmissions 4 WORLD LUBRICANT USES
Detergents Dispersants Engine Cleanliness, keep sludge in suspension Antiwear/EP Reduce wear, minimize metal to metal contact Antioxidant Prevent formation of acid, minimize viscosity increase Viscosity Index Improvers Improves viscosity – temp. relationships Pour Point Depressants Modifies crystal growth at low temperature PERFORMANCE-WISE CLASSIFICATION OF ADDITIVES
Friction Modifiers Reduce Friction between moving parts, improve engine efficiency Corrosion/Rust/ Inhibitors Prevent Corrosion of Ferrous and Non-ferrous surfaces Metal Deactivators Neutralizes Catalytic Effect of Metals Tackiness Agents Improves Adhesive Properties Defoamant Control Foamings PERFORMANCE-WISE CLASSIFICATION OF ADDITIVES
DETERGENT/DISPERSANT ADDITIVE • Major Use in Crankcase Oil • Represent 70% of Total Additive Used in Engine Oil
FUNCTION OF DETERGENT/ DISPERSANT ADDITIVE • Keep Particulate matter dispersed • Maintain Engine Cleanliness DIRT IN ENGINE ARISES FROM • Below-by of products from incomplete combustion of fuel • Oil oxidation product • Engine wear Dirt Leads to Deposit in Engine e.g. On Piston Known as Lacquer or Varnish on English Sump Known as Sludge
DETERGENTS • Metal Containing Cleaning Agents • Capable of dealing deposits/precursor generated under high temperature running conditions
PARTS OF DETERGENT • A metal Al, Mg, Zn, Ba, Ca. • An anionic component e.g. carboxylate, Alcoholate, Phenate, Sulphonate and Salicylate. • Oil Soluble Oleo-philic Component Straight or Branched Alkyl Group.
TYPES OF DETERGENTS • Sulphonate • Phenate • Salicylate • Phosphate • Neutral • Over Base By-product of white oil Synthetic From Alkyl Aromatic
OVER BASE ADDITIVES • Colloidal Disperson Of Metal Carbonate (10-3-1 Micron) • TECHNOLOGY IS COMPLEX TO MAKE STABLE SUSPENSION • ESTIMATION As TBN (500) Metal Ratio • EFFECTIVE IN CONTROLLING a) Corrosive Acid From Oil Oxidation b) Blow-by Of Combustion Product
PREPARATION OF OVER BASE ADDITIVE • Phenate Over Base Are Prepared Similarly • Phosphates are Phosphoric And Thio Phosphoric Acid Derivatives
SELECTION DEPENDS ON • Severity Of Condition • Anti Rust • Anti Oxidant • Load Carrying Properties
DISPERSANTS • Non metallic ashless cleaning agents • Effective in controlling cold-sludge in gasoline engine operating under low-temp. stop-start conditions • Bipolar molecule having polar head non-polar tail Head consist of P,O,N atoms Tail HC moiety
ADDITIVES TYPES • Succinimides • Succinate Esters • Mannich Type • Phosphorus Based
MECHANISM OF ACTION • Polar Group Absobs on Dirt Oliophillic Group Solubilize Complex in Oil • React Dirt Precursors e.g. neutralizing acidic matter • Solubilizing precursors within their micelle structure. • Absorb on metal surface • Form coating on solid particulate and prevent their agglomeration to form large particles.
USES OF DETERGENT / DISPERSANT ADDITIVES • Essential for most of automotive oils • Automotive oil for gasoline/diesel • Rail road engine oil • Marine Oil • Two stroke engine • Tractor Oil • Automatic Transmission Fluid
OXIDATION INHIBITOR (AO) • Lubricants like other natural products deteriorate during use when exposed to oxygen. • Undergo complicated aging process. • Oxidation alter performance. • 1st oxidation product is hydroperoxides. • Hydroperoxide leads to variety of end products like alcohol, aldehyde, ketone acid etc. • Eventually depositing as sludge, varnish, liquer. • Leading to equipment failure
R-H R` + H`R` + O2 ROO`Antioxidant perform as radical quenchersR` + AO RH + AO`2 AO` INERT PRODUCTS MECHANISM OF ACTION
Engine oil accounts 60-70% of automotive lubricants. • 40-50% of all lubricants sold • Automotive engine oil driving force on AO market • AV car temperature – 100o • Hot spot temperature – 300o or more • Chain branching reactions are more prevalent in high temperature oxidation. For lube antioxidants is a mixture of peroxide destroyer (TDDP) and radical scavenger.
ADDITIVE TYPE • Zn-Di-Thio phosphate • Phenol • Aromatic Nitrogen Compounds • S- and P- Based Antioxidants • Phenothiazine and Alkyl Derivatives
USES OF ANTIOXIDANTS • Antioxidants are used in all type of Lubricant • Cranckase Oil Mostly Use ZDDP • Steam Turbine Hindered Phenol • Jet Air Phenothiazine Derivatives
OTHER COMPUNDS GENERALLY USED IN ADDITION TO ZDDP O RO – P – H OH RO CH2 OR RO – P – OR OR NH R C8H17 C8H17 S S N CNX2 X2NC S – M – S S O (XOC – CH2 – CH2)2 S, X – S – X, or X – Se - X HINDERED PHENOL DIPHENYL AMINE PHENOTHIAZINE DITHIOCARBAMATES X= Alkyl, Aryl, alkylaryl ORGANIC SULPHIDE OR SLENIDES
VISCOSITY INDEX IMPROVER AND POUR POINT DEPRESSANTS • These are polymeric additives • These additives are used to improve rheological properties of oils • They do it by purely physical means
VISCOSITY INDEX IMPROVER • VI is a number showing viscosity temperature characteristic of oil. • Gear, Transmission, Crankcase oil should have (a) Low viscosity at low temperature for startup (need low friction drag) (b) Sufficient viscosity at higher running temperature.
TYPES OF VI IMPROVERS • Oil Soluble Org. Polymer • M wt range 50,000-150,000 (a) Hydrocarbons (b) Esters
TYPES OF VI IMPROVERS HYDROCARBON TYPE • PIB Poly-isobutylene • OCB Olefin Co-polymer Poly Alkyl Styrene • HSDC Styrene Butadiene Co-polymer Styrene – Isoprene Co-polymer ESTER TYPE PMP [Poly Alkyl Acrylate Styrene Maleic Acid Copolymer]
USES OF VI IMPROVERS PMA 21%, HSDC 17%, OCP 67% VI improver made possible the advent of multigrade oils e.g. SAE low 30 or SAE 15w40 for gasoline engine (67%) diesel engine (19%).
SELECTION DEPEND ON • Requirement • Other prop e.g. PPD, Dispersant • Shear Stability • Oxidation Thermal Stability
MECHANISM OF VISCOSITY MODIFICATION IN OIL Oil associated with polymer Exist as random coil • Swollen by lube oil • Volume determine viscosity increase • At low temp. polymer remain as compact mass • At high temp. coil open up • Compensate fall in viscosity Polymer LOW Solubility GOOD Temperature LOW HIGH
USES OF VI IMPROVERS • Automotive multi grade oils (engine, gear) • Gear and transmissions oils • Hydraulic fluids • Industrial oils • Dosage 2-6%
POUR POINT DEPRESSANTS • At low temperature wax crystalize out and prevent flow of oil • Dewaxing can reduce pour point - Reduces yield - Adversely effect VI • PPD – syn chemical which prevent congelation • PPD offer effective and economical alternative to dewaxing • PPD improve - Low temperature fluidity - Low temp performance • PPD mainly used in paraffinic oils
TYPES OF PP DEPRESSANTS • Non Polymeric • Polymeric Recent Lit. indicate that majority of products are poly hydrocarbon HC-Ester co-polymer and ester co-polymer
MECHANISM OF ACTION (POUR POINT DEPPRESANT) • PPD don’t’ prevent crystallization • Change crystal habit • Probably by adsorption • Smaller crystals form • Do not interlock • Permit flow of oil
USES OF PP DEPRESSANTS • Mono and multi grade Oil • Gear & Transmission oil • Hydraulic Fluid • Compressor Oil • Machinery Oil
LOAD CARRYING ADDITIVES (AW/EP) • Aw and EP additives are incorporated to extend oil’s load carrying capabilities • Important but less used • Inter metallic contact occur at asperities under boundary lubrication resulting heavy wear
TYPES OF ADDITIVES • Additive are active compounds of S,Cl and P S-Compounds Dibenzyl disulfide • Butyl phenol disulfide • Sulfurised vegetable oils • Pb, Sb, Cd and Zn dithiocarbamates Cl – Compounds Chlorinated wax • Chlorinated fatty acids
TYPES OF ADDITIVES P - Compounds Tri cresyl phosphates ZDDP • Di-alkyl phosphates etc • P & S-Compounds Zinc dialkyl dithio phosphates Cl & S - Compounds Chlorinated alkyl sulfide • Sulfurised chloronaphthalene
MECHANISM OF ACTION • Act by physical adsorption, chemisorption or chemical reaction with metal forming protective film • Film not penetrated by asparities • Prevent scoring and surface damage
USES OF AW/EP ADDITIVES • Engine oil • Gear and transmission oil • Shock absorber oil • Hydraulic oils
FRICTION MODIFIERS (FM) • During start-up and shut-down sliding surfaces subjected to high load (mixed friction range) • FM additives used, to prevent stick-slip oscillation, noise and reduce frictional force • To save energy, reduce fuel consumption (additives known as FM) • FM Similar to AW/ EP Additives
TYPES OF FRICTION MODIFIERS • FM are polar oil soluble materials Only few gained commercial Acceptance • Mo-dithiophosphate and carbonate complexes • Dispersion of MoS2, graphite, PTFE • Ash less carboxylic acid esters, their oligomers and amines, amides
MECHANISM AND USES • Mechanism • By physical adsorption • Uses • Engine oil • Gear and transmission oil • Industrial oil • greases, etc.
ANTIFOAMING AGENTS • Requires where violent churning or agitation of oil occur Effect of Foams on the Performance of Engine • Rise oil level,results in loss of oil • Oil feed pressure drops, • Insufficient oil supply
TYPES OF ADDITIVES • POLYMERIC i) Poly organo siloxane CH3 CH3 CH3 Si O Si O Si O CH3 CH3 CH3 ii) Poly acrylate Iii) poly ethylene oxides DOSAGE 4-15 ppm n
MECHANISM OF ACTION • Oil insoluble • Lower interfacial tension between air and oil • Permitting easy aggregation of air • Reduce foam stability
USES ANTIFOAMING AGENTS • Engine oils (automotive, rail, marine) • Gear oils • Automotive transmission fluids • Industrial oils • Metal working oils
RUST AND CORROSION INHIBITORS • Rust and corrosion of metal parts undesirable • Leads to wear and break down
RUST INHIBIOTRS • RESULT OF CHEMICAL ATTACK OF WATER IN PRESENCE OF OXYGEN
TYPES OF RUST INHIBITORS • A large variety of compounds patented mostly three types: a. Neutral b. Acidic c. Overbased • Most Popular are • High mil. Wt. Carboxylic acid (Succinic acid) • Sulphonic acid • Phosphoric acid and their salts • Compounds formed by neutralization of these acids with organic base (e.g. Amines)