![PIZEOELECRIC TRANSDUCER
• Convert electrical potential into mechanical motion. amorphous lead
barium titanate, PdBaTiO3 or lead zirconate titanate, Pb [ZrxTi1–x]
Fig:- Pizeoelectric Transducer](https://image.slidesharecdn.com/manish-200726175611/85/Manish-Composites-ppt-48-320.jpg)
Manish Composites ppt
- 1. A PRESENTATION ON FABRICATION TECHNIQUES OF COMPOSITES Submitted to- Submitted by- Dr. Mukesh Kumar Manish Kumar Jangid Assistant Professor (2019PPE 5486) Dept. of Mechanical Engg.
- 2. CONTENT • Physical vapor deposition • Filament winding • Reaction bonding • Characterization techniques 1.AFM • Characterization techniques 2.TGA
- 3. DEPOSITION • Applying a thin film on a surface ranges from nano meters to micro meters. • Thin film is deposited on Substrates. • Different techniques are used for deposition PVD, CVD, sputtering, electroplating & coating.
- 4. PHYSICAL VAPOR DEPOSITION • Physical coating process involve, condensation & evaporation of material • PVD is used for high melting point & low vapor pressure materials. • PVD is carried out at high temperature and vacuum. • In contrary to PVD, CVD is a method in which chemical adhesion or chemical deposition occurs.
- 5. MARPHOLOGY OF PVD • High temperature is required to vaporize the material • Vacuum of different ranges is used which depends on the mean free path required in the system.
- 6. PVD TECHNIQUES • Evaporative deposition • Electron beam vapor deposition • Pulsed laser deposition • Sputter deposition • Ion induced deposition • Cathode Arc Deposition
- 7. EVOPRATIVE DEPOSITION • Resistive heating method is used. • deposition is performed at high temperature & low vacuum • Vacuum decreases the content of Contamination • In this Voltage & current is manually controlled. Fig:- Evoprative Deposition
- 8. ELECTRON BEAM VAPOR DEPOSITION • Electron beam is generated by tungsten filament. • Material is placed in Graphite or tungsten crucible • Deposition mechanism is same • deposition is carried out under high Vacuum • Deposition is controlled, and Uniform Fig:- Electron beam vapor deposition
- 9. PULSED LASER DEPOSITION • High power laser is used for deposition. • Argon or neon is used for inert atmosphere. • High vacuum is formed • laser is focused by lens, target decides the position of the deposition. Fig :- pulsed laser deposition
- 10. SPUTTER DEPOSITION • Sputtering works on the bases of momentum principle, formed by the collision of the atoms and molecules. • Plasma glow, ion accelerator or radioactive emitting is used to evaporate material. • argon gas is used for inert atmosphere. • Types of sputtering • Chemical and etching sputtering • Electronic sputtering • Potential sputtering Fig:- Sputter Deposition
- 11. CATHODE ARC DEPOSITION • In this process ions are deposited on the substrates with plasma. • Cathode arc deposition works under vacuum conditions using specially designed deposition heads. • C A Deposition can be operated in either DC or Pulsed modes. • This process is used for IC fabrication, micro circuit printing nano printing or pattering . & lithography. Fig :- Cathode arc deposition
- 12. ION BEAM DEPOSITION • Ion beam deposition is a process of applying materials to target through the application of ion beam • An ion beam deposition apparatus typically consist of an ion source, ion optics and the deposition target. • In the ion source materials in the form of a gas, an evaporated solid, or a solution ( liquid) are ionized. • For atomic ion IBD, electron ionization, field ionization or cathodic arc sources are employed. Fig:- Ion beam deposition
- 13. APPLICATIONS • PVD methods are commonly used in followings: • Circuit & IC fabrications. • Aerospace in TBC & transparent coatings. • Reflectors and optics
- 14. APPLICATIONS…
- 15. ADVNTAGES • Environment friendly then paint & electroplating. • more than one PVD technique can be used for coating. • Usually topcoats are not required. • Good strength and durability. DISADVANTAGES • Cooling systems are required. • Mostly high temperature and vacuum control needs skill & experience. • PVD coated materials has no chemical interaction with the surface that
- 16. FILAMENT WINDING • Filament winding is a fabrication technique mainly used for manufacturing open or closed cylinders like pressure vessels tanks or axisymmetric hollow structures. Fig:- Filament winding process
- 17. REQURIMENT FOR MANUFACTURING • Filament Winding Machines • Mandrel • Fiber Creels • Resin Bath
- 18. FILAMENT WINDING MACHINE • Basically similar to Conventional Lathe Machine performing turning operation
- 19. SCHEMETIC OF FILAMENT WINDING MACHINE
- 20. PROCESS • A large number of fiber rovings are pulled towards the resin bath. • Before entering the bath, rovings are gathered in the form of band by passing them through stainless steel comb. • At the end of the resin bath, the resin impregnated rovings are pulled through a wiping device to remove excessive resin. • Once the rovings have been thoroughly impregnated and wiped, they are gathered on a flat band and positioned on mandrel. • The band former is usually located on the carriage which traverses back and forth parallel to the mandrel
- 21. PROCESS
- 22. Contd…. • In turn , mandrel rotates at lower speed to get precise winding. • After winding a number of layers of desired thickness, the filament- wound part is cured in mandrel. • The mandrel is extracted from cured part. • The component is normally cured at high temperature before removing the mandrel. • As in pressure vessels , mandrel becomes an integral part of filament wounded part.
- 23. MATERIAL USED • E-glass, S-glass, • Carbon fibers • Aramid • Boron fibers • RESINS - Epoxy , Vinyl ester , Polyester , Polyurethane ,Phenolics, Polyamides
- 24. TYPES OF WINDING • There are three types of winding based on wind angle (The angle of roving band with respect to mandrel axis is called wind angle. Wind Angle of 0 to 90 degreed can be obtained) • Helical Winding • Circumferential Winding • Polar Winding
- 25. Contd…. Helical Winding Circumferential Winding Polar Winding
- 26. • For a Circular Mandrel where N= Rotational speed of Mandrel V= Carriage Feed Rate R= Radius of Mandrel Ө= Wind Angle
- 27. PARAMETERS • Process Properties • Fiber Tension • Fiber Wet-Out • Resin Content. • Material Properties • Environmental Properties
- 28. FIBER TENSION AND RESIN CONTENT • Fiber Tension is created by pulling the rovings through a number of fiber guides placed between the creels and resin bath. • Adequate fiber tension is needed to maintain fiber alignment in mandrel and resin content. • Mechanical actions on fiber in resin bath such as looping generally creates additional fiber tension. • Typical tension values range from 1.1 to 4.4N. • Excessive fiber tension can cause • Difference in resin content in inner and outer layers • Residual stresses in finished product • Large mandrel deflections.
- 29. FIBER WET OUT • Fiber Wet-Out depends on • Viscosity of resin at operating temperature • Number of strands in a roving that determines accessibility of resin to each strand. • Fiber Tension. • Speed of winding • Length of Resin bath. (For good Wet-Out , each roving should be under resin bath for 1/3 to ½ seconds in a bath of 20cm)
- 30. MATERIAL PROPERTIES (RESIN) • The viscosity of resin bath should be low enough for impregnating the fiber strands in resin bath, yet not so low that resin drips and runs out easily. (Usually a viscosity of 1-2 Pa-s is preferred) • Should have relatively long pot life. (Pot life is the amount of time taken for an initial mixed viscosity to double) • Should be chemically inert. • Shouldn’t change its composition when subjected to high temperature.
- 31. APPLICATIONS • Storage tank • Railway tank car • Pipe • Aerospace applications
- 32. APPLICATIONS…
- 33. ADVANTAGES • Highly reproducible nature of the process • Continuous fiber over the entire part • High fiber volume is obtainable • Ability to orient fibers in the load direction (10° minimum winding angle) • Fiber and resin used in lowest cost form • Size of component not restricted by oven or autoclave size • Process automation (particularly with high volume) results in cost savings
- 34. DISADVANTAGES • Defects such as voids , delamination and fiber wrinkles • Part configuration must facilitate mandrel extraction • Mandrel could be complex and expensive • Inability to wind reverse curvature • Inability to easily change fiber path within one layer • Wound external surface may not be satisfactory for some applications
- 35. REACTION BONDING • Reaction bonding or reaction sintering, is a important means of producing dense covalent ceramics. Fig:- Reaction bonding of ceramics
- 36. REACTION BONDING PROCESS • In this process has the great advantage that problem with matrix shrinkage during densification avoided • Silicon cloth is prepared by attrition milling a mixture of silicon powder, a polymer binder , and an organic solvent to obtain a dough of proper consistency. • This dough is then rolled to make a silicon cloth of desired thickness. • Fiber mats are made by filament winding of silicon carbide with a fugitive binder.
- 37. Contd… • The fiber mats and silicon cloth are stacked in an alternate sequence, debinderized, and hot pressed in a molybdenum die in a nitrogen or Vacuum environment. • At this stage, the silicon matrix is converted to silicon nitride by transferring the composite to a nitriding furnace between 1100⁰C and 1400 ⁰C . • Typically the silicon nitride matrix has about 30% porosity, which is not unexpected in reaction bonded silicon nitride.
- 38. REACTION BONDED SILICON NITRIDE (RBSN) • Reaction-bonded silicon nitride (RBSN) is made from finely divided silicon powders that are formed to shape and subsequently reacted in a mixed nitrogen/hydrogen or nitrogen/helium atmosphere at 1,200 to 1,250 °C (2,200 to 2,300 °F). • The nitrogen permeates the porous body and reacts with the silicon to form silicon nitride within the pores. • The piece is then heated to 1,400 °C (2,550 °F), just below the melting point of silicon. Precise control is exercised over the nitrogen flow rate and the heating rate
- 39. REACTION BONDED SILICON CARBIDE • Reaction-bonded silicon carbide (RBSC) is produced from a finely divided, intimate mixture of silicon carbide and carbon. • Pieces formed from this mixture are exposed to liquid or vapors silicon at high temperature. • The silicon reacts with the carbon to form additional silicon carbide, which bonds the original particles together. • Silicon also fills any residual open pores. Like RBSN, RBSC undergoes little dimensional change during sintering. Products exhibit virtually constant strength as temperatures rise to the melting point of silicon
- 40. PROPERTIES OBTAIN THROUGH REACTION BONDING • Although up to 60 percent weight gain occurs during nitriding, dimensional change is less than 0.1 percent. This is a “net shape” process, which allows for excellent dimensional control • Reduces the porosity present in the material • High heat temperature strength • Creep resistance of RBSN and RBSC are quite good.
- 41. ADVANTAGES and DISADVANTAGES • Advantages • Large volume fraction of whiskers or fiber can be used. • Multidirectional, continuous fiber preform can be used • Fiber degradation can be avoided. • Disadvantages • The great disadvantage of this process is that high porosity is difficult to avoid.
- 42. APPLICATIONS • Alumina beads • Alumina ceramic beads • Silicon carbide seal ring • Silicon nitride seal ring. Fig:- Reaction bonded silicon carbide Fig :- Reaction bonded silicon nitride
- 43. ATOMIC FORCE MICROSCOPY • AFM works by scanning a probe over the sample surface, building up a map of the height or topography of the surface as it goes along Fig:- Atomic force microscopy
- 44. BACKGROUNG OF AFM • In 1929 Shmalz described Stylus Profiler. • In 1950 Becker suggested oscillating the probe that approach contact with surface. • In 1971 Young described non contact type Stylus Profiler. • In 1981 Binning and Rohrer described STM. • AFM Invented in 1986 by Binning
- 45. Different from other microscopy • No need of focusing, illumination, Depth of field. • It also have height information that make it simple to quickly measure the height, volume, width of any feature in the sample. • It physically feels the sample’s surface with a sharp probe, building up a map of the height of samples surface. • It provides single atomic level structure so provide high resolution
- 46. COMPONENT OF AFM • The main components of an AFM are • 1.Microscope stage – Moving AFM tip, Sample holder, Force Sensor • 2.Control electronics - Optical Microscope, Vibration controller • 3.Computer - The control electronics usually takes the form of a large box interfaced to both the microscope stage and the compute
- 47. BASIC COMPONENT OF AFM INSTRUMENT • The piezoelectric transducer moves the tip over the sample surface, the force transducer senses the force between the tip and the surface, and the feedback control feeds the signal from the force transducer back in to the piezoelectric, to maintain a fixed force between the tip and the sample
- 48. PIZEOELECRIC TRANSDUCER • Convert electrical potential into mechanical motion. amorphous lead barium titanate, PdBaTiO3 or lead zirconate titanate, Pb [ZrxTi1–x] Fig:- Pizeoelectric Transducer
- 49. FORCE TRANSDUCER • It may be constructed that measure forces as low as 10 pico newtons
- 50. FORCE SENSOR • Optical lever sensor the End of the cantilever bends the position of the laser spot on the detector changes. As the cantilever detector distance is large a small movement of the cantilever causes a large change in the laser spot position at the detector. Fig:- Force sensor
- 51. FEEDBACK CONTROL • Feedback control is used to maintain a set force between the probe and the sample
- 52. SCANNING MODES • There are different imaging modes of AFM • Contact Mode • Non Contact Mode • Tapping Mode
- 53. MODE OF OPERATION IN AFM • Mode of Operation Force of Interaction • Contact mode strong(repulsive) - constant force or constant Height • Non-contact mode weak (attractive) - vibrating probe • Tapping mode strong (repulsive) - vibrating probe
- 54. CONTACT MODE • High Resolution Images. • Tip of the probe always touching the sample. • Fastest of all the topographic modes. • Because of repulsive forces tip and sample may damage. • Sensitive to the nature of sample. • Not good for soft sample.
- 55. NON CONTACT MODE • Signal-to-noise benefits associated with modulated signals. • Oscillating modes can measure images with a small probe–sample force
- 56. TAPPING MODE • No Capillary effect. • Amplitude signals are used in feedback. • Used for Imaging in Air
- 57. LIMITATIONS • AFM can only image a maximum height on the order of 10-20 micrometers and a maximum scanning area of about 150×150 micrometers. • The scanning speed of an AFM is also a limitation. • Highly Dependent on AFM probe
- 58. APPLICATIONS • It can image far more biological processes, such as imaging of proteins. • Any sample like ceramic material, human cells or individual molecules of DNA, Dispersion of metallic Nanoparticles can be imaged.
- 59. THERMOGAVIMETRIC ANALYSIS (TGA) • Principle: TGA measures the amount and the rate of weight change of a material with respect to temperature or time in controlled environments. • A TGA consists of three major parts a furnace, • 1. A microgram balance, • 2. An auto sampler • 3. A thermocouple.
- 60. INSTRUMENT • Instrument used for thermo gravimetry is “Thermobalance”. Data recorded in form of curve known as ‘Thermogram’ • The furnace can raise the temperature as high as 1000°C which is made of quartz. • The auto sampler helps to load the samples on to the microbalance. • The thermocouple sits right above the sample. • Care should be taken at all times that the thermocouple is not in touch with the sample which is in a platinum pan.
- 61. Contd… • A technique that permits the continuous weighing of a sample as a function of temperature and/or as a function of time at a desired temperature
- 62. Contd…. • A technique measuring the variation in mass of a sample undergoing temperature scanning in a controlled atmosphere. • Thermo balance allows for monitoring sample weight as a function of temperature. • The sample hangs from the balance inside the furnace and the balance is thermally isolated from the furnace.
- 63. SAMPLE PREPRATION • Sample preparation has a significant effect in obtaining good data. • It is suggested that maximizing the surface area of the sample in a TGA pan improves resolution and reproducibility of weight loss temperatures. • The sample weight affects the accuracy of weight loss measurements. • Typically 10-20mg of sample is preferred in most applications. Whereas, if the sample has volatiles 50-100mg of sample is considered adequate. • It is to be noted that most TGA instruments have baseline drift of ±0.025mg which is ±0.25% of a 10mg sample.
- 64. EXPERIMENTAL CONDITIONS • Experimental Conditions -Heating Rate Samples are heated at a rate of 10 or 20°C/min in most cases. • Lowering the heating rates is known to improve the resolution of overlapping weight losses. • Experimental Conditions -Purge gas Nitrogen is the most common gas used to purge samples in TGA due to its inert nature. • Whereas, helium provides the best baseline. Air is known to improve resolution because of a difference in the oxidative stability of components in the sample. • Vacuum may be used where the sample contains volatile components, which helps improve separation from the onset of decomposition since the volatiles come off at lower temperatures in vacuum.
- 65. CALIBERATION • Blank test • Calibration of mass changes • Calibration of temperature
- 66. APPLICATIONS OF TGA • In an overview of thermal analysis testing it is always preferable to do a TGA experiment on unknown samples before doing a DSC experiment (especially for pharmaceuticals). • Decomposition of pharmaceuticals renders products which are insoluble and generally sticky on the inside of a DSC cell. • These products will lower the life use of a DSC cell. • Therefore, know the decomposition temperatures of all drugs and heat in a DSC evaluation to 50°C below those temperatures.
- 67. Contd… • Evaporation of free (unbound) water begins at room temperature due to dry gas flowing over the sample. • Dehydration/Desolation of bound water almost always begins at temperatures above room temperature and typically 125°C. • Decomposition can have multiple stages (weight losses) but the presence of multiple weight loss steps can also indicate the presence of multiple components in the sample.