What does it mean that it is a contact force?If I want to push an object, which way will the force of push act? (demonstrate) Which direction would the friction force have?What will happen to the object when I push it? Is it going to slide forever (elicit that friction slows things down and stops them) ?Images:http://www.roymech.co.uk/images11/friction.gif
How did you know there was higher friction for wooden floor? – because the block didn’t go as farWHY?- depends on the surface material (rigid or soft) and texture (rough or smooth). Also, ice has a thin layer of water on top which acts as a lubricant (so similar to oil in a car engine). This is why we can do ice skating or skiing. It is not possible in very low temperatures when it is too cold for liquid water to be present on top of ice.
SEMINAR ON ADVANCES IN TRIBOLOGY BY APURV VERMA 3RB09ME011 DEPARTMENT OF MECHANICAL ENGINEERINGBHEEMANNA KHANDRE INSTITUTE OF TECHNOLOGY, BHALKI
INDEX• INRTODUCTION• PRACTICAL OBJECTIVES OF TRIBOLOGY• FRICTION• TYPES OF MOTION• TRIBOLOGY IN PISTON RINGS AND CYLINDER LINER• WEAR AND ITS MECHANISM• LUBRICATION• SOYBEAN OIL AS FUTURE LUBRICANT OIL FOR IC ENGINES• PVD• TRIBOLOGY CONCERNS IN MEMS DEVICES• IMPACT OF TRIBOLOGY• ECONOMIC ASPECTS OF TRIBOLOGY
INTRODUCTION• It is a GREEK word TRIBOS means rubbing processes.• Tribology is the science and technology of interacting surfaces in relative motion.• Tribology tries to describe everything that happens when things rub together. TRIBOLOGY TRIANGLE
TYPES OF MOTIONThere are two types of motion between two moving parts.● Sliding motion e.g :- Piston in IC engine●Rolling motion e.g :- Bearings, wheels of automobiles
TRIBOLOGY IN PISTON RINGS AND CYLINDER LINER• Cylinder liner is fixed one and piston will slide up and down inside on it.• Friction exists between these parts , it results in wear.• It can be reduced by applying lubricant.
RECENT DEVELOPMENTS IN TRIBOLOGY• Soybean oil as future lubricant for IC engines.• Chemical Vapor Deposition (CVD)• Physical Vapor Deposition (PVD)• Tribology concerns in MEMS devicesDiamond CoatingUltrananocrystalline diamond (UNCD)Self Assembled Monolayers (SAMs)Cantilever Beam Array Technique
SOYBEAN OIL AS FUTURE LUBRICANT FOR IC ENGINES• Soybean oil is a vegetable oil extracted from soybean seeds.• It is easily available at low price. PROPERTIES OF SOYBEAN OIL :-> It has a high viscosity index up to 223.> Has comparatively high flash point 610°F.> Has good fire point about 650°F.> It has high pour point, it can be reduced by winterizing the soybean oil.
MERITS OF SOYBEAN OIL• Soybean oil is biodegradable, in general it is less toxic.• It is a renewable oil, so it reduces dependency of foreign petroleum products.• Ease of processing.
CHEMICAL VAPOUR DEPOSITION CVD is used to grow a thin layer of advanced materials on the surface of a substrate. Application:-• Integrated circuits, electronic devices and sensors.• Catalysts• Micromachines, fine powder and ceramic powder protective coatings.
CHEMICAL VAPOUR DEPOSITION Thin film is formed from gas phase components.
CHEMICAL VAPOUR DEPOSITION• Two types of CVD:-• LPCVD (Low Pressure CVD ) :- Good uniformity, Used for poly-Si, oxide, nitride.• PECVD (Plasma Enhanced CVD ) :- Low temperature process and high deposition rate. Used for oxide, nitride, etc.
CHEMICAL VAPOUR DEPOSITION Pressure sensor Resistance-heated furnace Quartz tube Trap To exhaust Si Wafers Pump Source gases Gas control system LPCVD Systems
PHYSICAL VAPOUR DEPOSITION• PVD is a fundamentally a vaporization coating technique, involving transfer of material on an atomic level.• It is an alternative process to electroplating.• The process is similar to chemical vapor deposition (CVD) except for the raw materials.• i.e. the material that is to be deposited starts in solid form, whereas in CVD the precursors are introduced to the reaction chamber in gaseous state.
APPLICATIONS OF PVD• PVD coatings are used to improve Hardness, Wear Resistance, Oxidation Resistance. Thus, such coatings used in variety of applications such as :-• Aerospace• Automotive• Surgical/medical• Dies and moulds for all manner of material processing• Cutting tools• Fire arms
TRIBOLOGY CONCERNS IN MEMS DEVICES• Friction and Wear are the biggest issues in blocking advances of MEMS technology.• Once SAMS and Diamond Coatings are more fully developed, MEMS technology will be able to more completely realize its potential.
DIAMOND COATINGS• Diamond has a variety of useful properties compared to Silicon – Low wear, low coefficient of friction, thermally stable, isotropic hardness• Diamond cannot be simply made into smaller and smaller flakes, then deposited on MEMS devices• Diamond (or diamond-like) film must be grown on surface.
UNCD ULTRANANOCRYSTALLINE DIAMOND• A “better” method for producing diamond-like films. Grain size is 2-5nm.• Unlike conventional diamond film CVD, C60 is introduced into the reaction along with CH4. – C60 collides with itself, creating C2 (carbon “dimers”) – These C2 molecules enter the diamond lattice. – An abundance of C2 is the goal of the UNCD creation process.
SELF ASSEMBLED MONOLAYERS (SAMs)• Two Types • Silane – deposits on silicon • Thiol – deposits on gold• Deposition Formations Deposition • Densely Packed O O O • Amorphous Structure Si Si Si Si• Functional group determines: OH OH OH OH O O O O Si Si Si Si Si Si Si Si • applications O O O O O O O O • hydrophilicity/hydrophobicity• Used as: • binders for subsequent molecules • lubricants• Common hydrophobic SAMS: • OTS (long chain hydrocarbon) • FDTS (long chain fluorocarbon)
CANTILEVER BEAM ARRAY TECHNIQUE• Cantilever beams are fabricated of Beam Structuresdifferent lengths• Cantilevers are put into contact withsurface• Longer beams adhere to surface• Longest beam that does not sticksignifies adhesion force• SAM coated beams adhere afterlonger lengths than oxide surface
ECONOMIC ASPECTS OF TRIBOLOGY• The LUBRICANT REPORT estimated an amount exceeding 500 million pounds can be saved in the civilian sector of UK by research in tribology.• The estimated 11 % total savings in annual US energy consumption is equivalent to some 16 billion US dollars by an expenditure in research and development o f an estimated twenty-four million dollars.• Analysis of the failure of boiler tubes indicate that about one-third of all occurrences were due to erosion.• In UK, the application of tribological principles can effect national energy savings. These are estimated at 468 to 700 million pounds per annum.
IMPACT OF TRIBOLOGY• Since the publication of the Lubrication Report there has been an increasing awareness throughout industry of the subject of tribology.• In the UK the National Centre for Tribology and Industrial Units of Tribology have been set up to provide advice t o industry on the utilisation of existing knowledge.• Tribology is now recognized universally and President Carter of U.S.A. declared it to be a generic technology underlying many industrial sections and the prospectus for an Industrial Tribology Institute at Rensselaer Technology Center has been presented.
REFERENCES• Mr. RAJSHEKHAR MATHAPATI• www.wikipedia.com• www.slideshare.com• www.google.com• Tribology In Industries by SUSHIL KUMAR• Engineering Tribology by G.W. STACHOWIAK• Industrial Tribology by M.H. JONES