Aircraft Heat Shield Materials

This assignment delves into the world of aircraft heat shield materials. It examines the properties and performance of different materials like copper, aluminum, titanium, and ceramic matrix composites. The analysis considers factors such as weight, thermal conductivity, and ease of fabrication. The document aims to provide a comprehensive understanding of the material selection process for aircraft heat shields.

APPLICATION OF TITANIUM(AND TITANIUM ALLOYS) ALLOYS AND CERAMICS
NATRIX COMPOSITES IN AEROSPACE ENGINEERING
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ABSTRACT
Titanium is a chemical transitional element with a metallic lustre, silver in colour. Manufacturers
in the aerospace industry opt to use titanium because it has high strength compared to its density,
it is corrosion resistant, it has low thermal and electrical conductivity, non-toxic, excellent
resistance to fracture, bio-acceptability and good ductility. Titanium alloys are particularly
important because they are used in the manufacture of aerospace parts such as jet engines.
Titanium alloys are also applicable in other fields such as military, medical prostheses, dental
implants and many others. Due to the lightweight nature if the titanium alloys, they are preferred
in the manufacture of aircraft fuselages.
Ceramic matrix composites are considered a new class of ceramic material and are obtained from
the embedment of carbon or ceramic fibres into the ceramic matrix. It has a low strain to failure
compared with the that of pure ceramic. Also, the composite has a low density. All these make
the composite to have a mass specific property that is incomparable to that of any other structural
material beyond 1000oC (Krenkel, 2008). . The composites have a high resistance to corrosion,
can withstand high temperatures, and they are lightweight.

INTRODUCTION
Advanced Materials are those that are as a result of modification of existing materials. The
resulting ‘new material’ is of superior quality. The purpose of the modification is to come up
with a material of high quality whose characteristics are fundamental to the application in a
given sector (Majaja, n.d.). Categories of advanced materials include superconductors, high
performance alloys, energy materials, composites and auxetic materials.
Advanced materials are applicable in many fields such as aerospace engineering, car
manufacturing and medical engineering. For the purpose of this report, I shall consider the
application of Titanium Alloys and Ceramic matrix composites in the field of aerospace
engineering especially aircraft manufacture. Planes and rockets and all other technology that may
be required to fly in aerospace are required to be light, strong and tough. Therefore, for a
material to be fit for use in the aerospace sector, it has to have the following characteristics
depend on what part it meant to manufacture;
i. Low Density.
ii. High Temperature Strength.
iii. Toughness.
iv. Fatigue Resistance.
v. Hot Corrosion Resistance.
From previous studies, both Titanium alloys and Ceramic matrix composites exhibit some of the
characteristics listed above hence may be considered to be used in the manufacture of parts to be
used in aerospace technology such as air engines. We shall analyze their properties, composition
and suitability to be used in the manufacture of parts.

Aircraft Manufacture (The Atlas Group, n.d.)

LITERATURE REVIEW
Aerospace engineering revolves around the concept, design and manufacture of aircrafts and
spacecrafts. Different types of materials have been used over time for aerospace purposes. In the
first stages of development and manufacture of airplanes, timber was widely used to fabricate the
wings of aircrafts. With continued research and development in the aerospace field, more
suitable materials were developed including use of metal. Today, materials used in the
manufacture of parts to be used in aircrafts or spacecrafts are of high quality and are used to
build certain parts depending on the requirements. Advanced materials that are able to achieve a
certain targeted property such as low density, durability or strength have been developed for use
in the manufacture of aircraft parts such as wings and engines.
1. TITANIUM AND TITANIUM ALLOYS
Titanium is a chemical transitional element with a metallic lustre, silver in colour . It has a low
density a high strength. It has low thermal and electrical conductivity, non-toxic, excellent
resistance to fracture, bio-acceptability and good ductility (Froes, 2015). Titanium is also
corrosion resistant when exposed to saline conditions Metals that are obtained as a result of the
combination of titanium and other chemical elements are known as Titanium alloys. Chemical
elements such as molybdenum, aluminum, vanadium and iron to produce alloys of low density
but high strength. The elements that are alloyed with titanium have varied effects on the
properties of titanium. Tin, iron, aluminum and vanadium have shown to increase the ultimate
tensile strength and the tensile yield strength but reduce ductility and toughness. Titanium alloys
are particularly important because they are used in the manufacture of aerospace parts such as jet
engines. Titanium alloys are also applicable in other fields such as military, medical prostheses,
dental implants and many others.

Property Value
Atomic number 22
Atomic weight 47.9 g
Density 4.5 Kg/cm3
Compressibility 0.8×106cm/cm/K
Melting point 1668oC
Boiling point 3260oC
Heat of fusion 5020 Cal/mole
Physical properties of unalloyed titanium (Joshi, 2006)
Of all metallic elements known to man, none has a higher strength to density ratio than titanium
up to 550oC (Bhatnagar & Srivatsan, 2009). This property coupled with high resistance to
corrosion makes titanium and its alloys the ideal material to be used in the aerospace field. The
most common tanium alloys that are used in aerospace technology Ti 6Al-4V (Grade 5) which is
used in the manufacture of aircraft turbines, engines and other structural parts. This alloy is
preferred due to its high resistance to corrosion, low density and high strength all which are an
ideal requirement for any material to be used in the manufacture of aircrafts. Below is a brief
description of specific areas of aerospace application
1. Helicopters- Titanium alloys are used in the highly stressed parts including the rotor
head.
2. Aircraft fuselages- Due to the lightweight nature if the titanium alloys, they are preferred
in the manufacture of aircraft fuselages. The Alloys have also been used to stop the

growth of fatigue cracks in fuselages. This is done by applying the titanium alloy in thin,
narrow rings around the fuselage. This ensures that potential cracks do not propagate to
the surface of the aircraft.
3. Space related application- The pay load of space vehicle is significantly small hence the
need to save on weight for the aircrafts. Titanium and its alloys were used in the first
Apollo and mercury programs (Bhatnagar & Srivatsan, 2009).
4. Air frames of aircrafts
5. Manufacture of aircraft Engines- “The figure below shows examples of titanium alloy
applications for the V2500 engine employed by Airbus A320. The V2500 engine is
manufactured by International Aero Engines, an international joint venture that includes
Japanese enterprises. Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.1Si alloys are most
commonly used for the manufacture of aircraft engines” (Ikuhiro, et al., 2014).
Figure: Application of titanium in an aircraft engine (Ikuhiro, et al., 2014)

Conventional structural ceramics such as silicon nitrade alumina have one weakness i.e. they are
highly susceptible to cracking when mechaninal load is applied on them. This has resulted in the
development of ceramic composites so as to try and overcome these weaknesses.
2. CERAMIX MATRIX COMPOSITES
Ceramic matrix composites are considered a new class of ceramic material and are obtained from
the embedment of carbon or ceramic fibres into the ceramic matrix. The resultant material is
called Ceramic Fibre Reinforced Ceramic. The bonding forces between the fibre and the matrix
is very low hence the composite hence the interface is weak. This combined with the porosity of
the matrix is important because it results to a low strain to failure compared with the that of pure
ceramic. Also, the composite has a low density. All these make the composite to have a mass
specific property that is incomparable to that of any other structural material beyond 1000oC
(Krenkel, 2008). Introduction of fibre in the matrix has also improved the cracking resistance
capabilities of the ceramic. Ceramic composites have also proven to have a higher resistance to
thermal shock and elongation compared to the pure ceramics.
Ceramics matrix composites are being used in place of ceramics as they overcome the
weaknesses of the pure ceramic such as brittleness. The composites have a high resistance to
corrosion, can withstand high temperatures, and they are lightweigh (Narottam & Jacques,
2015)t. This properties make them ideal for use in the aerospace industry. The following are
some of the areas in the aerospace field where their application has been of immense
contribution to improving the quality, efficiency and reliability of the concern parts.

1. Jet engines- According to general electric, use of ceramic composites reduces the weight
of the engine as they are lighter resulting to reduction in the centrifugal force in the
engine which will lead to design of smaller engine shafts (Kellner, 2016).
2. Heat shield for space vehicles- Temperatures in the heat shield may rise up to 1500oC.
With temperatures this high, many structural materials would lose their integrity.
Ceramic matrix composites can withstand this temperature and still remain structurally
stable and ensure resistance to thermal shocks.
DISCUSSION AND CONCLUSSION
1. TITANIUM AND TITANIUM ALLOYS
The main body of an aircraft is referred to as the aircraft fuselage. The fuselage is considered the
third in importance after the wing and tail. This is the part that holds the crew, passengers and
cargo i.e. the cockpit, cabin compartments for passengers and cargo (Sadraey, 2013). One of the
requirements for a material to be used to manufacture the airframe is that it must be ductile. This
ensures a faster process of fabricating the required shape. Other important qualities that are
considered when determining the suitability of a material to be used in aircraft manufacture are
conductivity(electrical and thermal), density, toughness, hardness, malleability, elasticity
contraction, expansion, and fusibility and others (Federal Aviation Authority, n.d.). The fuselage
is the largest part of an aircraft body hence the material used for its construction should be

lightweight but strong so as to control the final weight of the resulting product. As stated
previously, titanium has a high strength to density ratio hence it make titanium and its alloys the
most suitable candidates for the manufacture of the airframes and fuselages. Other alternative
materials that may be considered for the use in airframes are aluminium and aluminium alloys.
Aluminium is a chemical element with a metallic lustre and in its purest is white in colour. It is
ductile and malleable and offers the highest resistance to corrosion. Alloys of aluminium are
mainly from the combination with silicon, manganese, chromium and magnesium. Aluminium is
lightweight and corrosion resistant hence can be considered in the making of airframes.
However, compared to titanium, it has a lower strength value. Aluminium is cheaper compare to
titanium and it has the best corrosion resistance.
The aircraft engine is that part that propels an aircraft by generating mechanical power. In a
commercial jet engine, air enters through the front and compressed. The compressed air is forced
to enter the combustion chamber. In the chamber, fuel is then sprayed onto the compressed air
then ignited. As a result of the combustion, gases are produced and then released at the back of
the engine. As the gasses escape with pressure on the back, they produce a thrust that propels the
aircraft forward. A large amount of air is sucked into the engine at a rate of 1.2 tons per second.
The combustion of air and fuel results into burning temperatures of up to 2000oC. The material
that is to be used in the manufacture of the engine require to accommodate high temperatures and
pressure. The preferred material should be tough, hot corrosion resistance, lightweight, fatigue
resistance and high temperature strength. Titanium and its alloys can satisfy those requirements.
Even at high temperatures, titanium remains structurally stable and is highly resistant to
corrosion. This make it the ideal candidate for use in jet engines.

2. CERAMIX MATRIX COMPOSITES
A heat shield is a structure designed to protect other parts from external heat by absorbing,
dissipating or reflecting it. Spacecraft enter the atmosphere of planets at very high speeds and
depend upon air resistance to slow them down. The resulting friction leads to aerodynamic
heating which can lead to the part or whole of the spacecraft. This implies that spacecrafts have
to be protected from these very large temperatures. Heat shields are provided for this reason.
Ceramic matrix components are have low density, are resistant to corrosion and thermal shock
resistance. Ceramic matrix components used in the heat shield can withstand the resulting
temperatures (close to 1500oC) and still remain structurally intact. Alternative materials that cn
be used in the heat shield include copper and aluminium. Copper is often used to make heat
shields for terrestrial purposes. The main disadvantage in using copper is that it is not as light as
aluminium or titanium. Copper is preferred to aluminium because it ealisy joins to copper and
stainless steel (Seely, et al., 2011).

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