Workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA Essay Example

WОRKBООK QUЕSTIОNS FRОM TЕХTBООK МАTЕRIАLS, THЕIR РRОРЕRTIЕS, TЕSTING АND SЕLЕСTIОN BY SHЕЕDY, РА

Presented to

February 20, 2021

Distinction between elements, compounds and Mixtures

An element is a substance which consist of only one kind of an atom and cannot be broken down into simpler matter either physically or chemically. Elements exist either as atoms or molecules. Example of elements are nitrogen and argon.

A compound is made up of two or more elements that are bound together. Compounds can be broken down into simpler matter chemically but not physically. An example of a compound is water which is made off oxygen and hydrogen.

A mixture is a substance that is made up of two or more compounds and/or elements that are intermingled physically. Elements and/or compounds making up a mixture can be separated using physical means.

Question 2

Purpose of reinforcement

Concrete

Concrete has very high compressive strength but very weak tensile strength. Thus, it easily shears when exposed to tensile strength. To make it withstand tensile stress, concrete is reinforced with material that has high tensile strength such as steel.

Plastic is known to have low modulus and temperature limitations. Reinforcement of plastic is thus done by reinforcing it with fiber glass to eliminate both the low modulus and temperature limitations.

Question 3

Distinguishing factor between ceramic material and metals.

The distinguishing factor between metals and ceramics is that; metals are good conductors of both heat and electric current while ceramic materials are poor conductors of both heat and electrical current. Example of ceramic materials include compounds like carbides, oxides and nitrides.

Question 4

Composite material;

This is a material that has been made by a combination of two or more materials. Example of a composite material is fiberglass.

Question 5

Differences between metals and non-metals

Metals and nonmetals have differences in both the physical and chemical properties. This are as shown in table 1 below.

Chemical differences

Non – metals

Easily lose their valence electrons

Easily gain valence electrons

Resultant oxides are basic in nature

Resultant oxides are acidic in nature

Forms the reducing agent in a reaction

Forms the oxidizing agent in a reaction.

Table 1 showing chemical difference existing between nonmetals and metals

Physical Differences

Non-metals

Good conductors of both heat and electrical current

Poor conductors of heat and electrical current

Malleable

Non-ductile

Table 2 showing physical differences between metals and non-metals

Nature of Materials

Question 1

Atomic Structure of oxygen

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA

Question 2

Why ionic compounds are non-conductors in solid state but conductors in liquid state

Ionic compounds are as a result of reaction between metals and nonmetals. Since the metals are positively charged and the non-metals are negatively charged, there is formation of an ionic bond. As a result, the oppositely charged ions are arranged in a regular way in solid state forming giant ionic lattices, forming crystals. When the compound is dissolved in water, the ionic bond between the crystals are broken and as a result, the ions becomes mobile and consequently causing conduction of electricity.

Question 3

Pure water is a non-conductor

Question 4

Normal tap water is a conductor since it contains ions that result into conduction of heat and electricity

Physical properties of Materials

Question 1

There are several factors that control heat transfer through a solid. This include;

  1. Temperature difference

The higher the temperature gradients between the conducting medium the higher the rate of heat transfer.

Heat conduction is attributed to interaction of adjacent particles in the conducting medium. Thus, the rate of heat conduction is indirectly proportional to the length of the conducting medium. These is illustrated in the equation below

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 1

Where workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 2the rate of heat is transfer and workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 3 is the length of the conducting medium

  1. Cross – sectional area

Heat transfer is predominantly depended on the cross – sectional area of the conducting medium. This can be illustrated in the equation below.

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 4

From the equation, it can be conclude that an increase in the cross – sectional area increases the rate of heat transfer.

Question 2

The loops are built at regular intervals to provide flexibility so as to cushion the transporting pipe against the compressive stress of the fluid being transported that would have caused buckling.

Question 3

When building a furnace lining, a material with a very high heat capacity is required. This is due to the fact that a furnace is characterized by very high temperatures thus a material used for the lining should be able to withstand the high temperatures.

Question 4

This is a material that is characterized by extremely high melting point and has a tendency of maintaining its initial structural properties at extremely high temperatures.

Question 5

As temperature increases, the resistivity of a conductor decreases.

Question 6

Insulating oil should be of high dielectric strength to withstand the strong electric field produced by the transformer.

Question 7

Ferromagnetism is applied in the design of recording devices such as floppy discs, cassette tapes among others. This devices inputs information in the form electrical signals and eventually, they permanently encode it into a magnetic material.

Question 1

Construction of a thermocouple is such that two wires of different materials, mostly copper and constantan, are used. This wires are welded together at one end and on the other end, they are separated by an insulating material. In measuring temperature, the thermocouple is placed on a surface onto which temperatures is to be measured relative to another point of different temperature. This creates a temperature gradient and as a result, there is flow of DC current in the two dissimilar wires. The current flowing is directly related to the temperatures being measured and upon calibration, temperature is measured.

Question 2

Electrical conductivity is given by the formula workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 5 . Thus to measure the electrical conductivity of a 25mm aluminum bar;

Current is set to pass through the given metal. The values of the voltage and the current through the bar is then measured by a multi-meter. To get the electrical conductivity, the measured values of voltage and current are inserted into the above stated equation.

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 6

Question 3

A calorimeter is a measuring instrument designed to measure heat transfer either to or from any given object.

Question 4

To measure the density of a small ceramic insulator, the following procedure is followed.

  1. The mass of the ceramic cylinder is measured using a balance

  2. The ceramic insulator is then inserted into a graduated cylinder filled with known volume of water. The change in volume is then measured, this is the volume of the ceramic insulator.

  3. Using the formula,workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 7 density is then calculated.

Question 5

Aluminum is used as a heat sink for most electronic components because;

  1. It’s a good conductor of heat, thus it has the ability to conduct heat away from the electronic components.

  2. It is machinable, thus it can be easily machined to make heat sinks

  3. It’s light and thus does not add extra heavy weight on the electronic components.

Question 1

  1. To determine proof strength, a stress – strain curve of the given metal is drawn.

  2. A parallel line to the tangent of the initial stress – strain curve or the initial straight part is drawn from the origin at a distance amount representing the defined residual strain.

  3. The stress at which the line cuts the original stress – strain curve is the proof stress.

Question 2

The mass to be used when undertaking a Brinell hardness test for a 10 mm diameter indenter is 300kgs. The result is expressed as;

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 8

Question 3

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 9

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 10

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 11

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 12

Question 4

Determination of transition temperature of a metal is important since it helps determine the metal properties in different temperature conditions.

Question 1

Non – destructive tests are carried out to allow the inspection of materials without causing damage to the materials.

Question 2

Precautions necessary when carrying out liquid penetrant testing are;

  1. The penetrant material should be kept out of fire since they are flammable.

  2. The contact between the penetrant material and the skin should be avoided since the materials are corrosive to the skin.

Question 3

Magnetic particle methods are used in testing ferromagnetic materials.

Question 4

Methods used to detect internal defects in casting are;

  1. Liquid penetrate test

  1. The surface of the material to be tested is prepared by ensuring it’s free from any grease, water, or oil.

  2. After cleaning the surface, the penetrant material is then applied either by brushing, immersing the material in the penetrant or spraying.

  3. The penetrant is then left on the surface for some time to ensure it is drawn into the defects. The waiting time is usually specified by the manufacturer of the penetrant.

  4. Excess penetrant is then removed by either direct rinsing, or using a solvent.

  5. A developer is then applied on the surface of the material to extract the penetrant and left for sometime

  6. Inspection is then done using appropriate lighting to detect the defects.

  7. The surface is then cleaned.

  1. Magnetic particle inspection

  1. Surface cleaning is done using wire steel brushes, using solvents or shot blasting to remove grease, oil and any other impurities.

  2. A magnetic field is then induced either using an electromagnet of a permanent magnet. The inducing of the magnetic field is either longitudinal to detect parallel defects or circular to detect perpendicular defects.

  3. Magnetic particles are then applied in such a way that they are able to move on the surface of the material freely.

  4. Inspection of the defects is then done under suitable lighting conditions.

Question 1

Reduction is loss of oxygen and oxidation refers to addition of oxygen.

Question 2.

Conditions for corrosion to Occur

-oxygen.

-water (Moisture)

Question 3

Typical concentration cell,

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 13

Question 4

Process leading to inintergranur corrosion

Sensitization-This process involves chromium carbide precipitation at the boundaries of the grain, leading to formation of regions that are chromium depleted. Chromium is a corrosion inhibitor.

Question 5

Corrosion protection of steel. Electro-coating-This is the process in which particles that are electrically charged are deposited out of an electrolyte suspension e.g. water to coat metals ‘conductive part.

Question 6.

Thermal degradation: results from molecular deterioration as due to overheating of plastics. High temperatures cause separation of the long chains of the polymer, and react with another leading to change of polymer properties.

UV radiation degradation: Results from long exposure to sunlight. Tertiary carbon bonds in synthetic polymers are activated by UV rays to form the free radicals that further react with oxygen to produce carbonyl groups. This causes the exposed materials to crack and discolor leading to a disintegration.

Biological degradation: This method mainly involves water immiscible or water soluble plastics that are biodegraded by micro-organisms.

Question 1

Calcium hydrogen carbonate, Ca (HCO3)2

Magnesium hydrogen carbonate, Mg (HCO3)2

Question 2

-Boiling: It causes precipitation of magnesium carbonate or calcium carbonate, which is insoluble in water. This removes the ions from water, hence removing temporary hardness.

-Addition of lime (calcium hydroxide). Calcium hydroxide is added to precipitate the insoluble calcium carbonate.

Question 3

Magnesium sulfate (MgSO4)

Magnesium chloride (MgCl2)

Calcium sulfate (CaSO4)

Calcium chloride (CaCl2)

Question 4

Permanent water hardness can be removed by addition of sodium carbonate (Na2Co3). Magnesium and calcium ions in hard water react with the washing soda to produce insoluble carbonates.

Question 5

Course screening-This method removes larger particulate matter using a mesh.

ClarificationThis method involves addition of pH adjustment chemicals or chemical coagulants to form flocs. When the flocs settle, they are filtered out.

Softening-It involves the addition of soda ash (Na2CO3) or lime which reduces hardness.

Question 6

The chromate anodic inhibitors functions by oxidation of ferrous hydroxide to form gamma Fe2O3. The reduced chromate, Cr2O3incorporates into the protective layer. Combination of zinc/chromate produces cathodic inhibition.

Question 1

Viscosity of bitumen can be reduced by

  1. During the manufacture of the bitumen emulsion, it is manufactured in a medium that is composed very high bitumen concentration, and then diluted to the to the binder concentration that has the desired viscosity.

  2. Addition of additives

Question 2

Bitumen refers to hydrocarbons mixture that is naturally obtained or as a residue of cracking process while asphalt is the mixture composed of bituminous pitch and gravel and/or sand.

Question 3

Bituminous material flashpoint is the minimum temperature at which the bituminous material’s vapor takes fire momentarily in form of flash at specified conditions

Question 1

The cast iron has a 4% carbon impurity that makes it too brittle to use in engineering applications.

Question 2

White iron: This iron has a surface with a white, crystalline fracture along the plates of iron carbide. Applications: tools and utensils, fences, piping, structural connectors etc.

Gray iron: This iron has a gray fracture surface along the plates of graphite flakes. Application: decorative features, markers and plaques, ordnance etc.

Matrix iron: This iron exhibit a wide range of characteristics falling between white and gray iron. Applications: ordnance, tools and utensils.

Question 3

workbook questions from textbook Materials, their properties, testing and selection by Sheedy, PA 14

From the diagram above, it can be seen that a temperature of 15500

Question 4

In order to exhibit different properties of softness and hardness.

Question 5

Carburizing the steel: In this method, steel is placed in a carbonaceous environment at high temperatures for several hours. Diffusion of carbon into the steel surface makes it harder.

Pack method: The method involves packing parts to be hardened with a coke or charcoal compound, added with carbonates. The pack is subjected to very high temperatures, usually, (925°–955° C).

Nitriding: This method uses nitrogen and heat. Heat is applied by gas flame followed by immediate quenching of the set

Question 1

High grade coppers

Question 2

Beryllium copper is used in the manufacture of down–hole drilling tools in gas and oil industry.

Question 3

Types of brass are;

  1. Amorality Brass which is composed of 1% tin and 30% zinc. It is used in inhibiting dezincification.

  2. Aluminum Brass which is composed of aluminum. It is used in the manufacture of Euro coins.

  3. High brass that is composed of 35% and 65% copper. Used in manufacture of screws, rivets and springs.

Question 4

Gold silver alloys are used in Australian coinage.

Question 6

Non – ferrous alloys used in the manufacture of resistance heating elements include; Brass and Bronze

Question 7

Titanium is used as structural engineering alloys because it is corrosion resistance, its high strength at moderately lower temperatures.

Question 8

Refractory metals are metals that have the ability to resist extreme conditions of heat and wear.

Question 9

The two principal types of plastics are thermoplastics and thermosets. Thermoplastics are types of plastics that become soft when heated and hard when dried. Thermosets are types of plastics which cannot be altered by change in temperature.

Question 10

Ceramics are non-metallic inorganic materials that are made by mixture of clay and earthen elements.

Question 11

Types of glass include;

  1. Annealed glass

Question 1

It is necessary to maintain the reservoir metal since it helps prevent development of defects.

Question 2

The following is the description of casting processes.

  1. Sand casting – In the processes of sand casting, a metal in its molten state is poured into a mold cavity that has been developed from sand.

  2. Die casting – This process involves forcing a molten metal that is under high pressure into a designed mold cavity.

Question 4

Advantages of powder metallurgy metals

  1. They are environmentally friendly

  2. Minimal machining is required in their use

  3. They produce a very good quality surface finish

  4. They are resistant to corrosion

Question 6

Cold extrusion

This is a metal extrusion process that is done at room temperature.

Hydrostatic extrusion this is a type of impact extrusion in which fluid hydrostatic pressure is used in place of ram.

Question 7

  1. Plastic extrusion

This type of plastic molding involves the conversion of plastic material to a liquid state from a solid state and eventually reconstituting them into components that are finished.

  1. Injection molding

This method of plastic molding involves the processes of injecting molten plastic into a mold.

  1. Blow molding

This is a plastic molding formation which results into formation hollow components

Question 1

Properties of soft solder

Density of 7.37 g/m3

Thermal conductivity of between 55 and 60

Question 2

Types of soft solder used in electronic work is rosin – based

Question 3

Types of brazing alloys

  1. Low – temperature brazing alloys – This are alloys whose melting begins at low temperatures.

  2. Silver – copper phosphorous alloy – this is a type of alloy that contains 7% phosphorous, 93% copper and silver up to 18%.

Question 4

Electroslag welding process.

This is a welding process that involves heat generation by an electric current that is passing between the work piece and the filler material via a molten slag that is covering the surface being welded.

Bibliography

Sheedy, P. A., 1994. Materials : their properties, testing and selection. 3rd ed. s.l.:Forestville, N.S.W. : Technical Secretarial Service, 1994..