Properties AND Applications Of Engineering Materials Research Paper

Question 1: (Metallic Materials)

Recrystallization:
This is the process of growth of grain fragments in an alloy when it’s being worked on. This affects materials properties and services while in use.
Examples such as steel’s properties are affected such that there is reduction in strength and hardness of the material and this affects its applications and behavior in service. Other materials such as copper are affected in the same way.

Hot or cold working:

Hot or cold working involves hardening of materials and also and also heating the material. Iron is an example and is affected by hot working where it can be cast in different shapes desired to be used in the market and the same applies to other materials such as copper.

Alloying:

This refers a mixture or combination of two or more elements, at least one of which is a metal. Considering two alloys:

Brass made by copper and zinc is a metallic material.

The effects of alloying elements e.g. copper, improves the atmospheric corrosion resistance of the alloy and zinc gives the alloy excellent mechanical properties that include machinability hence the alloy is applicable in a wide range of engineering areas such as brazing making flexible hoses, architectural works condenser tubes etc.

Bronze.

It’s an alloy of copper and tin which is a metallic material where tin is used as an alloying element. Copper improves corrosion characteristics while tin improves the strength, tensional and compressional stress and thus can be used in making springs, heavy duty electrical switches and buildings (Callister, WFD and Rethwisch, DG 2011).

Question 2: (Thermoplastic Polymeric Materials)

Polymer processing temperature
Thermoplastic materials soften with the application of heat and require cooling in order to be set to shape. I will consider two thermoplastics:

Polythene/polyethylene (C2H4)n

When the processing temperature is raised, the polythene softens and thus its property of use at a wide temperature range is altered hence in use cannot be used in the common uses such as packing but the behavior is different since it can only be used.

Polyvinyl Chloride (PVC)

PVC is the cheapest and most widely used thermoplastic. When heat is increased i.e. temperatures are raised during processing, the resistance to impact decreases with time since during finishing, the material always softens beyond 800C thus its dielectric strength is altered and its behaviour during function has a low efficiency in used materials such as fabric coating and as a rubber substitute (Callister, WFD and Rethwisch, DG 2011).

Other appropriate process parameters (such as mould temperature, injection)

Mould temperature affects a material final shape and thus if high temperatures are used thermoplastics such as PVC and polythene will be affected and hence their behavior in service in not as required unlike thermosetting that are not affected. The material properties are affected hence not appropriate in the market and in injection moulding, the thermoplastic material are first compressed then passed to heat chamber and if this in not done according to the required conditions the material (thermoplastic) properties are affected.

Pressure (Injection speed)

Thermosetting polymeric materials mostly depend on heat to be formed but pressure and injection speed affect them also such as the PVC effects to the material are resistance to impact, self extinguishing when ignited, strong but high pressure impact the material negatively. The behavior of the PVC in service depends on the pressure used in processing such and thus uses as fabric coating, corrugated roofing, and rain water goods are good if the pressure used was good and appropriate. Polythene on the other hand is affected similarly as the PVC and the injection speed is key since it determines the shape and size to be produced (Callister, WFD and Rethwisch, DG 2011).

Question 3: (Thermosetting)

Mould temperature
Thermosetting materials usually malleable or liquid prior to cooling are affected by the mould temperature e.g.
phenol-formal dehyde (PF) (“Bakelite”).
Uncontrollable mould temperature and reheating the material result to the decomposition point being reached and hence cannot be shaped or melted and this affects its properties of being strong, rigid and dimensionally stable and resistant to heat, most chemicals and solvents.
Its behaviour in service is not as required since the processing was not favourable and appropriate hence affecting in negatively such as in electrical parts, lavatory seats.

Polyesters (Unsaturated polyesters)

Effects of mould temperature on it during processing depends on whether the temperature is appropriate and if it is not appropriate, the properties such as of being strong and rigid and resistant are affected and consequently its behavior in use such as thermal insulators and vacuum cleaner parts is also affected.

Moulding pressure and time.

PF is affected by the moulding pressure and time and its properties that mostly come after finishing is done are affected and if high pressure and time required are not appropriate the properties change such as resistant and rigid and also the behaviour in service while in use makes them not appropriate but if good mould pressure and time was appropriate the PF and polyesters work well as required.

Curing and time

Alumina cement-based concrete is processed and cured under given temperatures regulated by manufacturers’ technical documents of refractory concretes. Curing temperature has an impact on properties of concrete. The higher curing temperature cause hardening of
concretes, thus make concrete to shrink more (cardoso et al. 2004, p. 2073–2078).

Question 4: (Ceramics)

Water content of clay
The water content is key factor during processing of ceramics. Effects of water content on clay in ceramic materials such as brick and tiles, has effects on the material’s property where it is made more brittle and fails compression test. This affects its behaviour in service such as used since it is hard and strong thus becomes very brittle.
Another ceramic materials affected is functional pure clay oxides composed of MgO, AlO3 that affects their functionability and their behaviour in use.

Sintering pressure and time

Non-silicate ceramics are processed though high-temperatures treatment and sintering with little or no liquid. Sintering gives ceramic materials properties such as strength, elastic modulus, hardness, fracture toughness, thermal conductivity among other (Rahaman 1995). These properties such as those in clay product make them hard but very brittle, permeable to gases and liquids etc. Pressure sintering on the other hand increases contact pressure of particles ceramics materials during processing (German 1996). Ceramics produced through this method can withstand high temperatures while in use.

Firing temperature

Clay as a raw material is widely used in fields of ceramics. Ceramic application depend upon the composition, structure and physical properties of clay (Grimm, R 1960). In this process, the mechanical properties of clay such as compresion strength, modulus of rupture, density, shear strength and hardness vary with firing temperature change due to phase chemical reaction or changes between clay phases. Through firing temperature, optimum mechanical properties can be obtained.

Question 5: (Composite Materials)

Composite materials are formed from two or more materials producing properties not found in any single material consisting of filler and bonding materials. The two main example are fibrous and particulate (Callister, WFD and Rethwisch, DG 2011).

Fibre alignment

Here composites are distributed in terms of their diameter and characteristics. Continues aligned and discontinuous aligned are examples here and the effects if the fibre alignment is different are that the material’s shape is altered along the diameter or length hence behaviours in service is affected. This is same also for the discontinuous aligned if its altered in its struncture. In overall fibre provide significant strength to materials for example fibre glass which has continuous alignment.

De-lamination

Composites are assembled by lamination form layers that make it. The effects of this on properties are that the composite such as Reinforced Cement Concrete (RCC) or concrete becomes strong, resistant among others and its behaviour in service is improved and hence more applicable widely.

Matrix/ reinforcement ratio

Generally the composites ductility is desirable such as steel, tungsten, molybdenum and the properties if the ratio increases are improved and it becomes strong, durable, more ductile and while in use both composites materials’ behaviour is desirable and applicable.

Particle dispersion in cermet’s

Various geometrical and spatial characteristics of particles of dispersed phases influence the properties of composites e.g. in concentration, size, distribution, size and orientation. Cermet is a composite material composed of ceramic and metal materials such as turbine blades and concrete. Particle dispersion helps since joining of the ceramic material with metal is key hence its effects on the material such as turbine blades is; makes the cermet strong, resistant to corrosion and high tensional and compression strength.
The effect while in use is positive and very efficient both in industries and geothermal power plants and also hydro-electric power stations in turning of the turbines.

Question 6: (Smart Materials)

Applied force
A smart material, such as grease, which has lubricating properties, is used to aid when force is applied by reducing friction and protecting moving parts.

Electric fields

Conductivity, resistivity, among others are properties that are found smart materials such those found in electric resistors and actuators.
Magnetic fields
Electro/Magneto Rheological fluids respond to electric/magnetic field by changing its viscosity. This property gives a material the ability to resist gradual deformation which is caused as a result of tensile and shear stress (Anjanappa and Yu 1997, pp. 393-402). Magnetism depends on permeability as a material property. This property is commonly applicable in magnets, electric transformers, generators, electro-magnets among other.

Temperature change

Some materials like a magnetic allow are made from iron, cobalt, nickel and aluminium. Properties in these elements make any component made of these materials suitable to withstand high temperatures and corrosion resistance e.g. alnico magnets.

Colour Change

Smart materials e.g. paint, dyes among others have pigments that are used in finishing product. They aid in protection of surfaces against rust, dust, and give the beauty contrast on materials depending on surface area and lighting.

Question 7: (Wind Turbine)

A turbine blade is the component that makes up the turbine body or section of the whole turbine. Materials used to make the turbine blade are such as; super alloys, cermets.

Super alloys

This are specially prepared alloys, which are high temperature alloys that are resistant to high temperatures. They exhibit many key characteristics such as; mechanical strength, resistance to thermal creep deformation, resistance to corrosion or oxidation good surface stability.

This improves the standards of the alloy and hence suitable in use in the turbine and aerospace industry.

Cermets
This are composite materials composed of ceramics and metal materials. They posses both the ceramic and metallic properties such as hardness and resistance to high temperatures for ceramics; and ability to undergo plastic deformation for metals.
Composition of metal in a cermet is usually less than 20% for this composite to be effective and efficient. The standards of its use in turbine industry are good also and as required.
Comparing the two range of materials provided, the super alloy slightly is higher in preference for use to make a turbine blade by the turbine company, since it has more properties and the economy in its creation and manufacture is not that high compared to the cermet.`
Availability is also considered and the elements/metals used in making the super alloy such as aluminium iron and copper are available compared to that requires use of a ceramic cermet.

QUESTION 8

Range of engineering materials to be used;
Carbon fibre composite
This is a reinforced polymer of thermoplastic which is extremely strong and light. It contains carbon fibre and this properties makes the material suitable for use in vehicle body parts e.g. in BMW.

Aluminium

Aluminium metal is usually strong, light, resistant to corrosion and can also b e used to make the vehicle body part but it is not that strong compared to other. However, its standards are improved when used to make alloys with metals e.g. iron, zinc etc.

Plastics

They are materials that are also used strong and when combined with some metal elements form composites and ceramic materials with properties that are desirable and required in making body parts.

All these materials meet a minimum of the required standard in making the BMW's body part.

Criteria used:
Availability of the material
Economy of use
Maintenance
Cost
Geographical destination of the product
The criteria is appropriate and recommended to be used while selecting a suitable material for use. Putting into consideration the destination for this material which is in the Middle East. Some other factors have to be considered. Middle East is generally very hot and therefore a material to be used has to be considered due to the climatic conditions. In regard to the above, carbon-fibre composite is preferred and therefore recommended.

QUESTION 9

IMPORTANCE OF CHOICE OF MATERIAL
In the car manufacture, the choice of material was based on the mechanical properties, were of materials, corrosion, ability to manufacture and lastly cost.
The mechanical properties of the car parts have to satisfy the reliability requirements as the material must be able to withstand a certain load. Therefore the material must possess a certain strength and stiffness. Selected materials are then examined for stiffness and strength value, and then potential materials further inspected for other desired properties. This portrays that for materials selection as dealing with various loads and temperature variations, one of the prime concerns (Callister, WFD and Rethwisch, DG 2011).
Wear of materials especially in the gear design is considered as wear-free materials are to be used. This gives rise to the many production techniques to improve wear resistance considered in design as requires great care. The materials should also be capable of withstanding corrosive environments for example metals like iron which are heavily prone to erosion have to be prepared i.e. through painting, surface coating, cathodic protection to resist corrosion to increase the service life and minimize the erosion therefore the material must be assured before selection to be fit and preferable.
The material must be fit for design as well as easily manufacture to be able to meet the cost of production making it profitable as a commercial product. This has be considered before selection as it varies with the manufacture methods, accurate dimensions to be considered and production machined with low costs involved. Cost being a critical fact during the selection as market competition is severe; it can be neglected when a top priority performance is give. Other factors include electrical conductivity and inability to meet maximum operating temperature.
Since development is a continuous process, there is an inevitable degree of overlap between the various categories of development. The current used materials are divided into three; - material already in use and can be improved or made cheaper for further development, materials already developed but have not been used in automobile construction and newly developed (high technology) materials. The selected materials meet specific performance criteria as observed through metallic materials that are constantly improved because the effect of each modification is based on quality, production requirement and costs.
Lamellar cast iron possessing relatively modest strength and toughness properties, quenched and tempered steels, produced in broad ranges of strength with good ductility are used where steels are unrivaled in their suitability for highly-stressed automobile components for a long time. With the development of ductile iron, it is possible for foundries to offer a multitude of components, which can withstand high degrees of stress. Quenched and tempered steels have disappeared in recent developments as are in high demand. This is the same to sheet forming steels.
Aluminium alloys also have wide application in automobile manufacture. This is with regard to the engine, transmission and axles which have been directed towards the chassis and the body where an increase in aluminium utilization is used in the doors and hoods or load bearing structures. Joining of aluminium with other alloys or steel components resist corrosion (Callister, WFD and Rethwisch, DG 2011).
Fibre-reinforced aluminium has occasional application in motor components with examples being as a reinforcement of the piston-head. Aluminium and magnesium alloys are used in light weight construction. Other alloying elements are also involved in the automobile manufacture such as tungsten to retain hardness and toughness at high temperatures and manganese to improve properties and its response to heat treatment by controlling the structure.

Bibliography

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Callister, WFD and Rethwisch, DG 2011, Materials Science and Engineering.
Cardoso, FA Innocentini, MDM Akiyoshi, MM and Pandolfelli, VC 2004, 'Effect of curing time on the properties of CAC bonded refractory castables', J. Eur. Ceram. Soc., vol.24, pp. 2073–2078.
German, RM 1996, Sintering and practice, New York, Wiley.
Grim, R 1960, Some applications of clay mineralogy, American Mineralogist.
Rahaman, MN 1995, Ceramic processing and sintering, New York, Marcel Dekker.