Material adalah tidak lebih dari matter of substance used to create certain thing. Engineering materials adalah materials used to for application of engineering works. Based on mechanical, physical, chemical dan manufacturing properties materials are selected according to application.
Mechanical properties of materials adalah strength (compressive atau tensile), toughness, stiffness, elasticity, plasticity, ductility, brittleness dan hardness. Physical properties of materials adalah density, conductivity (thermal atau electrical), acoustical (sound transmission atau absorption), optical, combustibility. Chemical properties of materials adalah composition (oxide atau compound), acidity atau alkalinity, weathering corrosion.
Manufacturing properties of materials adalah castability, machinability rating, machining speeds dan feeds dan for dimensioning purpose shape dan size.
Pemilihan material untuk required functioning application didasarkan pada beberapa faktor berikut:
Stresses to which workpiece atau component akan dikenakan.
Corrosion resistance.
Temperature, wear dan tear resistance.
Flexibility dan rigidity.
Easiness of manufacturing process.
Cost effectiveness untuk product development.
Availability of material.
Klasifikasi Engineering Material:
Depending upon nature of substance materials are classified as
Metals dan alloys
Ferrous metals
Non ferrous metals
Non metals
Ceramics
Polymers
Composites
Semi conductors
Bio materials
1. METALS DAN ALLOYS:
Metallic materials adalah combination of metallic elements.
Most prominent property of metals adalah electrons are non localized i.e. in atomic arrangement outer valency electrons do not belong to individual atom rather it belong to whole bulk of material. Non localized electron is free to carry charge to conduct electricity. Hence they are good conductors for electrical dan thermal charge.
Metals have lustrous appearance. At normal temperature majority of materials are in solid state, tetapi beberapa metals seperti mercury lies in liquid state.
Based upon presence of iron content metals are named as
Ferrous metals
Non ferrous metals
Ferrous metals:
Primary content of ferrous metals adalah iron dan carbon. Ferrous metals are magnetic dan are vulnerable to rust when exposed to moisture. Wrought iron won’t rust due to purity dan stainless steel due to presence of chromium.
Eg : iron, steel, etc.
Due to magnetic property ferrous metals are used in motor dan electrical applications.
Non Ferrous Metals:
Iron is not primary content. Due to non presence of iron these metals have high resistance to rust dan corrosion dan they are non magnetic.
Eg: copper, brass, aluminium, tungsten, lead, zinc, gold, etc.
Alloy:
Alloy adalah combination of two or more metals. It is named based on metallic bonding character. It is of two types ferrous metal alloy dan non ferrous metal alloy. Cast iron adalah alloy made from iron, carbon dan silicon. Brass adalah alloy of copper dan zinc.
Aplikasi:
Due to toughness dan ability to sterilize at high temperatures metals are used as needles, surgical blades.
Due to strength dan ability to withstand heavy weights metals like iron dan steel are used in construction.
Metals like gold, silver, platinum, etc are used in jewellery.
Metals are used in machines dan automobiles as they can withstand high temperature, pressure dan workloads.
Aluminium dan titanium play important role in light weight category for aircraft alloys.
Tungsten is used in high temperature applications.
2. CERAMICS:
A particle atau fibrous which are used in terms of making ceramic products. Ceramics have regular atomic structure dan crystal structure. Ceramics are mainly oxides, nitrides dan carbides. They are non conducting materials, due to insulating property they are used as insulators. They are very hard dan brittle in nature.
Eg: alumina, silica, silicon carbide, diamond, bricks, etc.
Aplikasi:
Due to compressive strength bricks are used in construction
Because of good thermal insulation ceramic tiles are used in ovens.
Some ceramics are transparent to radar dan other electromagnetic waves are used in radomes dan transmitters.
Glass ceramics have high temperature capabilities so they are used in optical equipment dan fiber insulation.
Alumina, silica, silicon carbide are used in making tools.
Diamond is used in ornaments dan cutting tool applications.
3. POLYMERS:
Polymers have chain molecule structure of carbon as back bone atoms. They are mainly made up of tough organic materials. They are low density materials dan also flexible. In some cases polymers are not flexible.
Polymers are not only used as structural materials, they can be used as fiber dan resins in matrix of composite materials.
Eg : polyester as fibers, phenolics dan epoxides as resins.
Elastomers are also polymers but they are considered separately due to specific design for certain purposes like shock dan vibration absorption.
Natural polymers :
Eg : wool, silk, DNA, cellulose, proteins, etc.
Synthetic polymers:
Thermo plastics
Thermosetting plastics
Eg: nylon, polyethylene, polyester, Teflon, epoxy, Bakelite, etc.
Aplikasi:
Polyethylene is used for making carry bags.
Polypropylene is used for making high temperature resistance products like feeding bottle.
Polyether ether ketone dan polyethylene ketone are used in mineral water bottle concept.
Poly carbonate is used to make high performance polymers like transparent polymers
Polyaniline is a conducting polymer.
Bakelite used for making insulating materials.
4. COMPOSITE:
Composite material adalah composition of two or more constituent materials with different physical dan chemical properties to produce different characteristic material.
Composite material may be both metals atau metal dan ceramic atau metal dan polymer, depending upon application requirement combination is made.
CRPF dan honeycomb composites are used for chassis.
Some fuel tanks are made up of Kevlar reinforced fiber.
Reinforced thermosets are used in springs dan bumper system.
Fibreglass reinforced plastic has been used for boat hulls, fishing rods, tennis rackets, helmets, bows and arrows.
5. SEMICONDUCTORS:
Semiconductor adalah intermediate conducting material. Conductivity is not high as like metals dan low as like insulating ceramic materials. In these materials resistance decreases as temperature increases.
Unique atomic structure allows to control conductivity.
Eg : silicon, germanium, gallium arsenide, selenium, etc.
Aplikasi:
Gallium arsenide is widely used in low noise, high gain dan weak signal amplifying devices.
A semi conductor device can perform function of vacuum tube having hundreds of times its volume.
6. BIO MATERIALS:
Bio materials are non-viable materials .Eg : alumina, zirconia, titanium, tantalum, niobium, carbon, etc.
Aplikasi:
Metals are used in medicine to cure any micronutrient metal deficiency diseases in humans and animals, like iron is part of haemoglobin a bio molecule which can be used as ferrous sulphate to cure some forms of anemia.
Implants in body to repair or replace damaged tissue.
NOTE:
In composite materials name itself indicates as composite => composition, it is composition of two or more materials.
In semiconductors name itself indicates as semi (half) dan conductor (conducting)
Difference between alloy dan composite is that composite is reinforcement of other material. Whereas alloy is combination (mixture) of both or required number of materials in required quantity as per necessary product.
Both semiconductors dan bio materials are substitutes in metals, ceramics dan polymers in required places.
