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ASSIGNMENT 1

Name : Rizky Nur Fadhillah

NPM : 1006660270

Lecturer : Prof. Dr. Ir. Bondan T. Sofyan, M.Si.

QUESTION 1

 A. In your own words, describe what is a metal?!

Metal is the abundant natural resources in this earth. Resource that can be changed

into more useful something and have more selling points. Metal’s most widely used

 by humans because they have favorable properties such as high strength, can be as a

conductor of heat and electricity and the most important of metal’s properties arereadily deformable and ductility. There are several ways of metal forming process,

namely Forging, casting, stamping and Extrusion. Most elements in the periodic table

are metals

 B. What makes metals are commonly ductile?

The freedom of conduction electrons to migrate gives metal atoms, or layers of them,

the capacity to slide past each other. Locally bonds can easily be broken and replaced

 by new ones after the deformation. But this process does not affect the communal

metallic bonding very much. Because of that, metal have a ductile ability

C. Are metallic materials usually crystalline or amorphous? Offer your explanation.

Crystalline materials have atoms which are arranged in a regular or recurring at long

distances. Metals have metallic bonding where metal ions have been composed of 

solid and very good. Therefore I think metal is a crystalline material.

 D. Give three examples of engineering application of metals !

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• Uranium and Plutonium are used in nuclear power plants to produce energy

via nuclear fission

• Aluminum is used for motor vehicle components

• Steel is used for railway

  E Compare the possible fracture surface of metals, ceramics and 

 polymers on the same scale.

Based on the graphic above, metals are the most resistant material to fracture. because

metals have the metallic bonding and a very regular arrangement of atoms that make

the metal has a strong character. Different with ceramics which have high strength but

  brittle. And one more material is polymer, These materials typically have low

densities whereas their mechanical characteristics are generally dissimilar to the

metallic and ceramic materials they are not as stiff nor as strong as these other 

material types.

F Why do ceramic materials have lower ductility than metallicmaterials?

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Ceramic has a lower ductility than the metal because it has a different type of primary

 bonding with metals such as ionic and covalent bonding. So that the ceramic does not

have the freedom of electrons to move like in the metallic bonding, because electrons

exist in an ionic bond is used to stabilize and form bonds.

G Dissemble a torch. Investigate: (i) how many parts do you find in a torch, (ii)

investigate on what type of materials each part is made of.

• Case or Tube: holds all the other components of the flashlight. (POLYMER)

• Contacts: thin spring or strip of metal usually made of copper or brass that

serves as the connection between the battery, lamp, and switch. (METAL)

• Switch: can be in on or off position.(POLYMER)

• Reflector: plastic coated with a reflective aluminum layer to help brighten the

light of the bulb. (METAL+POLYMER)

• Bulb: usually very small.( CERAMICS)

• Lens: plastic cover in front of the bulb to protect the lamp which could easily

 be broken.(POLYMER)

• Batteries: Provide power to the flashlight.(METAL)

QUESTION 2

 A Compare the general characteristics of metals, polymer and ceramics and give 5

examples of the application of the three materials.

Metals :

Metallic bonding, high strength, high temperature resistence, good conductor of eeat

and electricity, ductile, readily deformable.

Application :

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• Uranium and Plutonium are used in nuclear power plants to produce energy

via nuclear fission

• Aluminum is used for motor vehicle components

• Steel is used for railway

• Coppers to make wire

• Iron is used for Bridge

Polymer :

Covalent bonding and Van Der Waals bonding, low strength, low temperature

resistance, insulator of heat and electricity, extremely flexible and corrosion resistance

Application :

•  Nylon (a generic term for polyamides) is used for parachutes

• Rubber is used for tire

• Plastic

• Fiber 

• Pipes

Ceramics :

Ionic and covalent bonding, high strength, high temperature resistence, Insulator of 

heat and electricity, brittle

Application :

• A lumina and Boron

carbide have been used in  ballistic armored vests to repel large-calibre rifle 

fire

•

Optical Flint (type of glasses) is used for lense

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• Floor 

• Ceramic balls can be

used to replace steel in ball bearings

•Ceramic is used for 

Astronout costum’s material because it is termal insulator 

 B What is composite material? Give three examples of structures made of composite

materials !

Composite material is a combined material which consist of more than one material

type. For example: concrete, tires, and fiberglass. Concrete is a combination of 

ceramic and metal composite, which is still observed when concrete cut or be seen as

a wall of steel and ceramic materials. Car tire is a composite of polymer composite

materials and metals, which when cut will be seen as a rubber polymer and steel wire

as the metal material. Fiberglass is a composite material with ceramic polymer 

composite, where the material is seen as the fibers of ceramic materials, and plastic as

a material which is also a matrix polymer.

C Describe and  

 give examples of crystalline and amorphous materials.

• Crystalline solids is an atom, molecule, or ion composition is packed in a

regular and recurring pattern extends in three dimensions. Examples: diamond,

silica and graphite.

DIAMOND

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• Amorphous solids are solids that the constituent particles do not have perfect

order.

AMORF USE OF

MATERIAL

Quartz glass Fiber opticsKhalkogenidaglass 

Membrane selenium

for photocopiersAmorphous silicon Solar cellsAn iron / cobaltamorphous

(Magneticmaterial)

polymer polistireneAmorphous carbon  black carbon

(adsorbent)

Amorphous structure of a glassy solid (left) and lattice structure of a crystalline solid

(right).

 D. Describe ionic bonding and give three examples of materials having this kind of 

bonding.

Ionic bonds occurs between metallic and non metallic elements. metallic element of 

the excess electron gives its electrons to the non-metals. After the handover of the

electron, it becomes a "electrical charge", which will become ions in such ties.

For example : sodium chloride (NaCl), MgO

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  E. Describe metallic bonding and the properties of materials possessing metallic

bonding.

Metallic bonding occurs between two of metals atom. In this case valence electrons

are not bound to any particular atom, they form a "gas" of electrons which freely

wander around metal ions.

The properties of metaliic bonding are :

• The complete delocalization of the electrons means metal “ions” are readily

interchacngeable → different alloys

• The electrons are easy to move → metals are good elecrical conductor 

• The metal ions pack together very well → metals have high densities and

assume simple crystallographic structures.