This document discusses several newly developed engineering materials including lead zirconate titanate (PZT), zirconium dioxide (ZrO2), amorphous silicon, and magneto rheological fluid. PZT is a piezoelectric ceramic used in sensors and actuators due to its ability to generate voltage or change shape with electric fields or temperature changes. ZrO2 is a ceramic material that can be stabilized in different crystal phases for uses like thermal barriers or insulators. Amorphous silicon lacks a crystalline structure but can be used in devices like thin-film transistors and solar cells when hydrogenated. Magneto rheological fluid increases viscosity when exposed to magnetic fields, allowing controllable damp

1. MATERIAL TECHNOLOGY
NEWLY DEVELOPED ENGINEERING MATERIAL

2. INTRODUCTION
Materials Technology is an interdisciplinary field involving the properties of
matter and its applications to various areas of technology and engineering. This
scientific field investigates the relationship between the structure of materials
at atomic or molecular scales and their macroscopic properties. It incorporates
elements of applied physics and chemistry. With significant media attention
focused on nanoscience and nanotechnology in recent years, materials science
has been propelled to the forefront at many universities. It is also an important
part of forensic engineering and failure analysis. Materials science also deals
with fundamental properties and characteristics of materials.

3.  LIST OF NEWLY DEVELOPED ENGG. MATERIALS
1. Lead Zirconate Titanate (PZT)
2. Zirconium Dioxide (ZrO2)
3. Amorphus Silicon
4. Magneto Rheological Fluid
5. YAG (Yteum aluminium garnets) laser
6. Stellites
7. Vatillium
8. Titanium alloy
9. Silicon Bricks

4. 1. Lead Zirconate Titanate (PZT)
 Lead Zirconate Titanate (PZT) is a ceramic material made of lead (Pb),
oxygen (O) and titanium (Ti) or zirconium (Zr).
 Chemical formula: Pb[ZrxTi1-x]O3; x = 0,52
 The atoms are arranged in a cubical structure.

5.  ATOMIC STRUCTURE OF PZT
 At temperatures below the Curie temperature (depending on the material
between 150°C and 200°C) the titanium atom moves from its central
position and the electrically neutral lattice becomes a dipole.
 This dipole lattice presents now piezoelectric characteristics and is
considered as one of the most economical piezoelectric material.
 By doping the PZT material, its piezoelectric characteristics can be modified:
especially the hardness or softness of the material.

6.  MAKING OF PZT
 Lead zirconate titanate , also called PZT, is ceramic perovskite material
that shows a marked piezoelectric effect. PZT-based compounds are
composed of the chemical elements lead and zirconium and the chemical
compound titanate which are combined under extremely high temperatures.
A mechanical filter is then used to filter out the particulates.

7.  APPLICATION OF PZT
 Being piezoelectric, it develops a voltage (or potential difference) across
two of its faces when compressed (useful for sensor applications), or
physically changes shape when an external electric field is applied (useful
for actuator applications).
 Being pyroelectric, this material develops a voltage difference across two of
its faces when it experiences a temperature change. As a result, it can be
used as a sensor for detecting heat.
 In 1975 Sandia National Laboratories was working on anti-flash goggles to
protect aircrew from burns and blindness in case of a nuclear explosion.
The PZT lenses could turn opaque in less than 150 microseconds.

8.  LIMITATION OF PZT
 High mechanical stress can depolarize a PZT ceramic.
 As the operating temperature increases, piezoelectric perfonamce of
material decreases .
 the curie point is the maximum exposure temperature for PZT. And it has
it’s own curie point. When this ceramic element is heated above the curie
point, all piezoelectric properties are lost.

9. 2. ZIRCONIUM DIOXIDE
 Zirconium dioxide , sometimes known as zirconia , is a white
crystalline oxide of zirconium.
 Chemical formula: ZrO2
 The atoms are arranged in a cubical crystal structure.

10.  Zirconium dioxide in powder form

11.  ATOMIC STRUCTURE
 Pure ZrO2 has a monoclinic crystal structure at room temperature and
transitions to tetragonal and cubic at increasing temperatures.
 The volume expansion caused by the cubic to tetragonal to monoclinic
transformation induces very large stresses, and will cause pure ZrO2 to
crack upon cooling from high temperatures.

12. Tetragonal
Monoclinic
Several different oxides are added to zirconia to stabilize the tetragonal
and/or cubic phases: magnesium oxide (MgO), yttrium oxide, (Y2O3), calcium
oxide (CaO), and cerium(III) oxide (Ce2O3)

13.  MAKING OF ZrO2
 Monoclinic zirconium dioxide formed by a process comprising : Melting
zirconium silicate into a induction melting furnace with a sintering crust
crucible at a temperature in a range of 2500° to 3000° C.
 Quenching the melt by drawing the melt off in a stream and cooling the
stream by subjecting the stream, while in a free fall, to a spray of fluid so
as to form thermally split zirconium silicate.
 Leaching out amorphous silica from the thermally split zirconium silicate
with alkali lye at 100° to 200° and a molar ratio of SiO2 to alkali hydroxide
of 1 to at least 2 so as to obtain zirconium dioxide.

14.  APPLICATION OF ZrO2
 The cubic phase of zirconia has a very low thermal conductivity, which has
led to its use as a thermal barrier coating or TBC in jet and diesel
engines to allow operation at higher temperatures.
 It is used as a refractory material, in insulation, abrasives and ceramic
glazes.
 Zirconia is also an important high dielectric material that is being
investigated for potential applications as an insulator in transistor in
future nanoelectronic devices.

15. • Products made from Zirconium Oxide (ZrO2)
 Bearing Technology in Automotive Engineering
 Cutters
 Dental Ceramics
 Drawing Tools
 Forming Applications
 Sealing Technology (Seal Rings, Bearings)
 Technical Cutters
 Tubes and Pipes

16.  LIMITATION
 Use of zincronia is more expensive then metal .
 It’s not easily available, number of process are required to get pure
zincronia.
 Less resistant to stress or extra force, there is a risk of chipping or fracture.

17. 3. AMORPHOUS SILICON
 Amorphous silicon (a-Si or α-Si) is the non-crystalline allotropic form
of silicon.
 Due to the disordered nature of the material atoms have a dangling bond.
 These dangling bonds are defects in the continuous random network and
cause anomalous electrical behavior.

18.  ATOMIC STRUCTURE OF AMORPHOUS SILICON
 Silicon is a fourfold coordinated atom that is normally tetrahedrally bonded
to four neighboring silicon atoms.
 In crystalline silicon this tetrahedral structure is continued over a large
range, forming a well-ordered crystal lattice.
 If desired, the material can be passivated by hydrogen, which bonds to the
dangling bonds and can reduce the dangling bond density by several orders
of magnitude.
 Hydrogenated amorphous silicon (a-Si:H) has a sufficiently low amount of
defects to be used within devices.

19.  MAKING OF AMORPHOUS SILICON
 In the manufacture of amorphous silicon, thin monocrystalline silicon wafers
are made by cutting a crystal of monocrystalline silicon. For further
processing these wafers are fixed on a polishing block. The exposed surface
of each wafer is then polished in order to remove the surface irregularities
which are caused by the cutting of the crystal of monocrystalline silicon.
Generally, the silicon wafers are processed in successive steps with grinding
or polishing agents of different particle size. These process steps comprise
the lapping and/or the so-called Blanchard grinding by which rough
irregularities are removed from the surface, and finally one or several
mechanical or chemical precision polishing processes which produce an
extremely smooth and defect-free surface which subsequently is subjected
to the known processing methods for making semiconductor devices.

20.  APPLICATION OF AMORPHOUS SILICON
 Amorphous silicon has become the material of choice for the active
layer in thin-film transistors (TFTs), which are most widely used in large-area
electronics applications, mainly for liquid-crystal displays (LCDs).
 Amorphous silicon has been used as a photovoltaic solar cell material.

21.  LIMITATION
 In this material the converge takes place below the temperature of 250K,
so the valance place has been occurred between the molecular of the
material.
 This limitation is known as hole mobility of the material.

22. 4. MAGNETO RHEOLOGICAL FLUID
 A magneto rheological fluid (MR fluid) is a type of smart fluid in a carrier
fluid, usually a type of oil. When subjected to a magnetic field, the fluid
greatly increases its apparent viscosity, to the point of becoming
a viscoelastic solid. Importantly, the yield stress of the fluid when in its
active ("on") state can be controlled very accurately by varying the
magnetic field intensity. The upshot of which is that the fluid's ability to
transmit force can be controlled with an electromagnet, which gives rise to
its many possible control-based applications.

23.  WORKING OF MR FLUID
The magnetic particles, which are typically micrometer or nanometer scale
spheres or ellipsoids, are suspended within the carrier oil are distributed
randomly and in suspension under normal circumstances, as below.

24.  When a magnetic field is applied, however, the microscopic particles
(usually in the 0.1–10 μm range) align themselves along the lines
of magnetic flux. When the fluid is contained between two poles (typically
of separation 0.5–2 mm in the majority of devices), the resulting chains of
particles restrict the movement of the fluid, perpendicular to the direction of
flux, effectively increasing its viscosity. Importantly, mechanical properties
of the fluid in its “on” state are anisotropic. Thus in designing a magneto
rheological (or MR) device, it is crucial to ensure that the lines of flux are
perpendicular to the direction of the motion to be restricted.

25.  Shear strength
 Low shear strength has been the primary reason for limited range of
applications. In the absence of external pressure the maximum shear
strength is about 100 kPa. If the fluid is compressed in the magnetic field
direction and the compressive stress is 2 MPa, the shear strength is raised
to 1100 kPa. If the standard magnetic particles are replaced with elongated
magnetic particles, the shear strength is also improved.

26.  APPLICATIONS OF MAGNETO RHEOLOGICAL FLUID
 Mechanical Engineering
Magnetorheological dampers of various applications have been and
continue to be developed. These dampers are mainly used in heavy
industry with applications such as heavy motor damping, operator seat/cab
damping in construction vehicles, and more.
 Military and Defense
The U.S. Army Research Office is currently funding research into using MR
fluid to enhance body armor. In 2003, researchers stated they were five to
ten years away from making the fluid bullet resistant. In addition, Humvees,
certain helicopters, and various other all-terrain vehicles employ dynamic
MR shock absorbers and/or dampers.

27.  Optics
Magnetorheological Finishing, a magneto rheological fluid-based optical
polishing method, has proven to be highly precise. It was used in the
construction of the Hubble Space Telescope's corrective lens.
 Automotive and Aerospace
If the shock absorbers of a vehicle's suspension are filled with MR fluid
instead of plain oil, and the whole device surrounded with an electromagnet,
the viscosity of the fluid (and hence the amount of damping provided by the
shock absorber) can be varied depending on driver preference or the weight
being carried by the vehicle - or it may be dynamically varied in order to
provide stability control.

28.  Human Prosthesis
Magnetorheological dampers are utilized in semi-active human prosthetic
legs. Much like those used in military and commercial helicopters, a damper
in the prosthetic leg decreases the shock delivered to the patients leg when
jumping, for example. This results in an increased mobility and agility for the
patient.

29.  LIMITATION
 High density, due to presence of iron, makes them heavy. However,
operating volumes are small, so while this is a problem, it is not
insurmountable.
 High-quality fluids are expensive.
 Fluids are subject to thickening after prolonged use and need replacing.
 Settling of ferro-particles can be a problem for some application.