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.
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.
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
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
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
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.
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
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.
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
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.
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.
