Biomedical Materials (2009) - Malestrom
Introduction
Ceramics are renowned for their excellent wear properties, good resistance to
degradation in corrosive environments, high modulus and hardness values and high
melting points. Equally well known are their poor thermal and electrical conductivities
and their reputation for being notch sensitive with low values of fracture toughness.
Historically, as a consequence of low impact and tensile strengths combined
with inherent brittleness, their use was limited. However, more recently, advances
in manufacturing technology have meant that a group of what can be termed high
performance engineering ceramics have emerged that can be used for a wide range
of applications. Their high melting point has led to their use in engines and turbines
at elevated temperatures. As a consequence of their improved toughness, they have
been incorporated in the design of body armour. Their excellent wear resistance,
high compressive strength properties, pleasing aesthetic appearance and proven biocompatibility
have led to the development of a specific range of what are referred to
bioceramics which are now used extensively in many different areas of medicine to
augment or replace parts of the body. Alumina and zirconia are used to manufacture
components of hip joint replacements; hydroxyapatite (HA) and glass ceramics are
used as coatings on prosthetic stems; calcium phosphate based materials are used as
porous scaffolds, spinal implants and bone grafts; composites of HA combined with
a polymer are used to manufacture replacements for the bones of the inner ear –
these are only a few examples of the wide range of applications of ceramics in medical
engineering.
This chapter is divided into two sections. The first defines ceramics, glasses and
glass ceramics in terms of their structure, processing and properties. The different
manufacturing routes involved in pressureless sintering, cold and hot isostatic
pressing, tape casting and liquid phase sintering are outlined. Production methods
for porous ceramics using burnt out polymer spheres (BurPS), foamed slips and
reticulated foams are described, as are the surface engineering techniques of ion
implantation and thermal spray coating. The effect of processing method and porosity
on the mechanical properties of ceramics are also considered. Following a brief
section on the structure and properties of bone, specific categories of bioceramics
are then introduced. These include dense forms of alumina and zirconia for weight
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Introduction
Ceramics are renowned for their excellent wear properties, good resistance to
degradation in corrosive environments, high modulus and hardness values and high
melting points. Equally well known are their poor thermal and electrical conductivities
and their reputation for being notch sensitive with low values of fracture toughness.
Historically, as a consequence of low impact and tensile strengths combined
with inherent brittleness, their use was limited. However, more recently, advances
in manufacturing technology have meant that a group of what can be termed high
performance engineering ceramics have emerged that can be used for a wide range
of applications. Their high melting point has led to their use in engines and turbines
at elevated temperatures. As a consequence of their improved toughness, they have
been incorporated in the design of body armour. Their excellent wear resistance,
high compressive strength properties, pleasing aesthetic appearance and proven biocompatibility
have led to the development of a specific range of what are referred to
bioceramics which are now used extensively in many different areas of medicine to
augment or replace parts of the body. Alumina and zirconia are used to manufacture
components of hip joint replacements; hydroxyapatite (HA) and glass ceramics are
used as coatings on prosthetic stems; calcium phosphate based materials are used as
porous scaffolds, spinal implants and bone grafts; composites of HA combined with
a polymer are used to manufacture replacements for the bones of the inner ear –
these are only a few examples of the wide range of applications of ceramics in medical
engineering.
This chapter is divided into two sections. The first defines ceramics, glasses and
glass ceramics in terms of their structure, processing and properties. The different
manufacturing routes involved in pressureless sintering, cold and hot isostatic
pressing, tape casting and liquid phase sintering are outlined. Production methods
for porous ceramics using burnt out polymer spheres (BurPS), foamed slips and
reticulated foams are described, as are the surface engineering techniques of ion
implantation and thermal spray coating. The effect of processing method and porosity
on the mechanical properties of ceramics are also considered. Following a brief
section on the structure and properties of bone, specific categories of bioceramics
are then introduced. These include dense forms of alumina and zirconia for weight
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