The document summarizes information about silicon nitride and barium titanate ceramic materials. Silicon nitride has high strength and fracture toughness even at high temperatures, making it useful for applications like engines and bearings. It is also biocompatible and used in orthopedic implants. Barium titanate has a perovskite structure and exhibits ferroelectric and piezoelectric properties. It can be used in capacitors and transducers due to these properties. Both materials have potential medical applications and are generally biocompatible.

1. Biomaterial Assignment
Presentation on ceramic
material :-
Silicon Nitride
& Barium Titanate

2. Silicon nitride
• Silicon nitride is a chemical compound of the
elements silicon and nitrogen, with the formula Si₃N₄.
• Silicon nitride (Si3N4) based ceramics are gaining more
attention due to their promising high-temperature thermal
and mechanical properties.

3. History
• Paul Schuetzenberger first reported a product with the
composition of the tetranitride, Si3N4, in 1879 that was
obtained by heating silicon with brasque in a blast furnace. In
1910, Ludwig Weiss and Theodor Engelhardt heated silicon
under pure nitrogen to produce Si3N4.
• E. Friederich and L. Sittig made Si3N4 in 1925 via
carbothermal reduction under nitrogen, that is, by heating
silica, carbon, and nitrogen at 1250–1300 °C.
• From 1948 to 1952, the Carborundum Company, Niagara
Falls, New York, applied for several patents on the
manufacture and application of silicon nitride.

4. • In 1953 British aimed at high-temperature parts of gas
turbines and resulted in the development of reaction-bonded
silicon nitride and hot-pressed silicon nitride.
• By 1958 Haynes (Union Carbide) silicon nitride was in
commercial production for thermocouple tubes, rocket
nozzles, and boats and crucibles for melting metals.
• Even though the properties of silicon nitride were well known,
its natural occurrence was discovered only in the 1990s, as
tiny inclusions (about 2 µm × 0.5 µm in size) in meteorites.
The mineral was named nierite .

5. Crystalline structure and properties
• There exist three crystallographic structures of silicon nitride
designated as α, β and γ phases.
• The α and β phases are the most common forms of (Si3N4) , and
can be produced under normal pressure condition.
• The γ phase can only be synthesized under high pressures and
temperatures and has a hardness of 35 Gpa.
Blue atoms are nitrogen and grey are silicon atoms
a)trigonal α (Si3N4) b)hexagonal β (Si3N4) c)cubic γ (Si3N4)

6. • The basic building unit is the silicon nitrogen tetrahedron, joined so that
each nitrogen is shared by three tetrahedra.
• They can be regarded as consisting of layers of silicon and nitrogen atoms
in the sequence ABAB... or ABCDABCD... in β-Si3N4 and α-Si3N4,
respectively. The AB layer is the same in the α and β phases, and the CD
layer in the α phase is related to AB by a c-glide plane.
• Due to the c-glide plane that relates AB to CD, the α structure contains
cavities instead of tunnels.
• The Si3N4 tetrahedra in β-Si3N4 are interconnected in such a way that
tunnels are formed, running parallel with the c axis of the unit cell
• The cubic γ-Si3N4 has a spinel-type structure in which two silicon atoms
each coordinate six nitrogen atoms octahedrally, and one silicon atom
coordinates four nitrogen atoms tetrahedrally.

7. Why β-Si3N4 is major form used ?
• The longer stacking sequence results in the
α-phase having higher hardness than the β-
phase. However, the α-phase is chemically
unstable compared with the β-phase.
• At high temperatures when a liquid phase is
present, the α-phase always transforms into
the β-phase. Therefore, β-Si3N4 is the major
form used in Si3N4 ceramics.

8. PHYSICAL PROPERTIES
• The material is dark gray to black in color and can be polished
to a very smooth reflective surface, giving parts with a
striking appearance.
• Key Silicon Nitride Properties
 High strength over a wide temperature range
 High fracture toughness
 High hardness
 Outstanding wear resistance, both impingement and frictional
modes
 Good thermal shock resistance
 Good chemical resistance

9. MECHANICAL PROPERTIES

11. BIOCOMPATIBILITY
• Silicon nitride (Si3N4) ceramic is an attractive material for
dental applications, especially used as a dental core material,
due to its unique properties including high fracture
toughness, high strength, high wear resistance and non-
cytotoxicity.
• Bone growth around silicon nitride implants—An evaluation
by scanning electron microscopy- The results showed that
silicon nitride can be used as biomaterial since the newly
bone grew around the implants.
• It can be used for orthopaedic biomedical to promote bone
fusion and to develop bearing that can improve the longivity
and wear of prosthetic hip and knee joints.

12. Medical Applications
• Silicon nitride - bioglass composite for biomedical applications
used in high load medical applications, to overcome the drawback
of low fracture toughness presented by most currently available
bioactive ceramics.
• Orthopaedic application.
• Silicon Nitride is leading a revolution in interbody fusion. AMEDICA
is the only company with the ability to manufacture interbody
fusion devices from medical-grade Silicon Nitride.
These devices:
 Are significantly stronger and more durable than PEEK
 May yield faster fusion: by way of a hydrophilic, microtextured
surface
 Are free of MRI or CT imaging artifacts: a major advantage for
intraoperative implant placement and postoperative fusion
assessment

13. General applications
• Automobile industry- material for engine parts like diesel
engine, glowplugs, precombustion chamber,turbo charger etc.
• Bearing- both full ceramic bearings and ceramic hybrid
bearings with balls in ceramics and races in steel. Example
high end automotive bearing, industrial bearing etc.
• High-temperature material- capable of surviving the severe
thermal shock and thermal gradients generated in
hydrogen/oxygen rocket engines.
• Metal working and cutting tools-
 cutting tools, due to its hardness, thermal stability, and
resistance to wear.
 recommended for high speed machining of cast iron.
• Electronics-used as an insulator and chemical barrier in
manufacturing integrated circuits.

14. References
• Santos, JD, Amaral, M, Oliveira, SM, Lopes, MA, Silva, RF
Silicon nitride - bioglass composite for biomedical applications
Key Engineering MaterialsKey Eng Mat
589 – 592
• B.S.bal , m.n. rahaman
Orthopedic applications of silicon nitride ceramic
Acta biomaterialia
1
• Deborah Gorth, Sabrina Puckett, Batur Ercan, Thomas J. Webster,
Mohamed Rahaman and B. Sonny Bal.
Decreased bacteria activity on Si3N4 surfaces compared to PEEK or
titanium
Nano medicine

15. Barium titanate
• Made up of barium ,tatanium and oxygen and
has a perovskite structure.
• It is a inorganic compound with chemical
formula BaTiO₃.
• It is a white powder and transparent as larger
crystals.
• This titanate is a ferroelectricceramic material,
with a photorefractive
effect and piezoelectric properties.

16. Crystalline structure and properties
• The solid can exist in five phases, listing from
high
temperature to low temperature:
hexagonal, cubic,tetragonal, orthorhombic,
and rhombohedral
crystal structure.
• All of the phases exhibit the ferroelectric
effect except the cubic phase.

17. • At high temperature cubic phase consist of octahedral TiO₆ at
centre , with Ti vertices and Ti-O-Ti edges.
• In the cubic phase, Ba2+ is located at the center of the cube,
with a nominal coordination number of 12.

18. Barium titanate and phase changes
• Above 120°C, barium titanate has a cubic structure.
• Below 120°C, it changes to a tetragonal phase, with an
accompanying movement of the atoms.

19. General Properties

20. Other properties like....
• Solubility- insoluble in water, slightly soluble
in mineral acid and dissolve in concentrated
hydrofloric acid.
• BaTiO3 ceramics with a perovskite structure
are capable of dielectric constant values as
high as 7,000, but other ceramics, like
titanium dioxide (TiO2), have values between
20 and 70.

21. Biocompatibility
•Porous BT does not exhibit short term cytotoxicity
and has potential for orthopaedic tissue
engineering applications.
•Active cell attachment and proliferation on
Negative BT surfaces. N-BTO is biocompatible and
effective in forming a Ca-P layer in MEM

22. Medical application
• Orthopaedic application
• The potential of barium titanate (BT) to be
electrically active makes it a material of
interest in regenerative medicine.

23. General Applications
• Barium titanate is a dielectric ceramic used for capacitors.
• It is a piezoelectric material for microphones and
other transducers.
• The pyroelectric and ferroelectric properties of barium titanate
are used in some types of uncooled sensors for thermal
cameras.
• High purity barium titanate powder is reported to be a key
component of new barium titanate capacitor energy storage
systems for use in electric vehicles.
• Barium titanate crystals find use in nonlinear optics.
• Barium titanate can be used as an electrical insulator in its
purest form.

24. References
• H. JEONG, I.-J. KWAK, H.-I. KIM, J.L. ONG, H.R. RAWLS, and Y.-J. PARK
Chonnam National University, Gwangju, South Korea,
Biocompatibility of Negatively Charged Barium Titanate Thin Film Formed on
Ti
1027
• L.N. Teixeiraa, G.E. Crippab, A.C. Trabucoa, R. Gimenesc, M.A. Zaghetec, D.B.
Paliotob, P.T. de Oliveiraa,A.L. Rosab, ,M.M. Beloti
In vitro biocompatibility of poly(vinylidene fluoride–trifluoroethylene)/barium
titanate composite using cultures of human periodontal ligament fibroblasts and
keratinocytes
• Ball JP1, Mound BA, Nino JC, Allen JB
Biocompatible evaluation of barium titanate foamed ceramic structures
for orthopedic applications.
US National Library of MedicineNational Institutes of Health