LECTURE 12.2. LECTURE OUTLINE Lesson 12 Quiz Lesson 12 Quiz.

LECTURE 12.2LECTURE 12.2

LECTURE OUTLINELECTURE OUTLINE

Lesson 12 QuizLesson 12 Quiz

Table 1.

Selected Physical and Mechanical Properties of Various Materials

Material Melting Point(˚C)

Specific Gravity(Density)

Young's Modulus(GPa)

Mohs'Hardness

MetalsAluminum 660 2.7 70 ~2.5Copper 1085 8.9 115 ~3Tungsten 3410 19.3 407 ~5

CeramicsAlumina 2045 4.0 400 9Mullite 1830 3.1 145 5Soda-Lime Glass ~1000 2.5 70 5.5

PolymersLDPE ~115 ~0.92 0.25 < 2HDPE ~137 ~0.95 1.05 < 2Nylon ~265 1.14 1.6-3.8 < 2

<Q1> Table 1 shows some of the materials that were listed as Table 3.4 in the book. Use this information to answer the following question.

The object is to design a scratch resistant counter-top for the kitchen. Which material would be employed for maximum scratch resistance?

<a> Soda-Lime Glass HDPE <c> Tungsten <d+> Alumina <e> Mullite

Table 1.





Mohs'Hardness




<Q2> Table 1 presents some property measurements for a series of materials, whilst Figure 1 plots the Young's modulii of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. The datum point marked A on Figure 1 corresponds to:

<a+> Alumina Tungsten <c> Copper <d> Mullite <e> Nylon

<Q3> Table 2 presents atomic numbers (At #), melting points (MP), specific gravities (SG) and Mohs' Hardnesses (H) for a series of metals, and their corresponding oxides.

The specific gravity of a metal oxide increases as the specific gravity of the metal increases.

<a> Always true <b+> Sometimes false

Metal At# MP(˚C)

H SG CeramicOxide

MP(˚C)

H SG

Magnesium(Mg)

12 650 2.5 1.74 Periclase(MgO)

2800 5.5 3.65

Aluminum (Al) 13 660 2.5 2.70 Corundum(Al2O3)

2050 9.0 4.0

Titanium (Ti) 22 1668 3.5 4.51 Rutile (TiO2) 1640 6.25 4.26

Manganese (Mn) 25 1244 3.5 7.47 Pyrolusite(MnO)

1840 6.25 5.43

Iron (Fe) 26 1538 3,5 7.87 Magnetite(Fe3O4)

1700 6.00 5.7

Copper (Cu) 29 1085 3.0 8.93 Cuprite(Cu2O)

1235 3.75 6.0

Zinc (Zn) 30 420 2.75 7.13 Zincite(ZnO)

1800 4.25 5.6

Tin (Sn) 50 232 2.0 5.77 Cassiterite(SnO2)

1127 6.5 7.0

Uranium (U) 92 1132 4.5 19.0 Uraninite(UO2)

2176 5.5 10.95

<Q4> Table 2 presents some properties of a variety of materials. Corundum is a <a> Metal <b+> Ceramic <c> Polymer <d> Composite. <F> Corundum is a compound; it is non-metallic, and inorganic; it is an oxide-ceramic.

Metal At# MP(˚C)

H SG CeramicOxide

MP(˚C)

H SG

Magnesium(Mg)


2800 5.5 3.65


2050 9.0 4.0



1840 6.25 5.43


1700 6.00 5.7


1235 3.75 6.0


1800 4.25 5.6


1127 6.5 7.0


2176 5.5 10.95

<Q5> Table 2 presents some properties of a variety of materials. Corundum is an ore for which metal?

<a> Magnesium <b+> Aluminum <c>Manganese <d> Iron <e> Copper

Metal At# MP(˚C)

H SG CeramicOxide

MP(˚C)

H SG

Magnesium(Mg)


2800 5.5 3.65


2050 9.0 4.0



1840 6.25 5.43


1700 6.00 5.7


1235 3.75 6.0


1800 4.25 5.6


1127 6.5 7.0


2176 5.5 10.95

<Q6> Figure 2 shows the variation in the Specific Strengths of a series of composites (and see Chapter 27), as a function of the percent of glass-fiber in the composite.

In order to attain a specific strength of approximately 105 MPa, the % fiber should be about

<a> 10 20 <c> 30 <d+> 40 <e> 50

Table 3.

Selected Materials and Selected Physical/Mechanical Properties.

Material Specific Gravity Young's Modulus(GPa)

Approximate YieldStrength. (MNm-2).

Alloy Steel 7.8 200 1000Aluminum Alloys 2.7 69 500Titanium Alloys 4.5 120 1000Beryllium Alloys 1.9 300 250

Wood 0.6 12 40Polyurethane Foam 0.1 6 1

Concrete 2.5 47 25Alumina 3.9 390 400

GFRP* 2.0 40 200CFRP** 1.5 270 650

<Q7>Table 3 presents the specific gravities, Young's modulii and yield strengths for a series of materials.

The specific modulus of an alloy steel is approximately <a+> 26MPa 13GPa <c> 128GPa <d> 260GPa <e> 1280GPa

Table 3.

Selected Materials and Selected Physical/Mechanical Properties.

Material Specific Gravity Young's Modulus(GPa)

Approximate YieldStrength. (MNm-2).

Alloy Steel 7.8 200 1000Aluminum Alloys 2.7 69 500Titanium Alloys 4.5 120 1000Beryllium Alloys 1.9 300 250

Wood 0.6 12 40Polyurethane Foam 0.1 6 1

Concrete 2.5 47 25Alumina 3.9 390 400

GFRP* 2.0 40 200CFRP** 1.5 270 650

<Q8> Table 3 presents some property measurements for a series of materials, whilst Figure 3 plots the yield strengths of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. The datum point marked A on Figure 3 corresponds to:

<a+> CFRP Titanium Alloys <c> Alloy Steel <d> Alumina <e> GFRP

<Q9> The semiconductor, gallium arsenide (GaAs) has a specific gravity of <Q9> The semiconductor, gallium arsenide (GaAs) has a specific gravity of about 5.5, and a Young's Modulus of approximately 100GPa. about 5.5, and a Young's Modulus of approximately 100GPa.

The location of GaAs on Figure 4a is at:The location of GaAs on Figure 4a is at:<a+> A<a+> A B B<c> C<c> C<d> D<d> D<e> E<e> E

<Q10> The semiconductor, gallium arsenide (GaAs) has a specific gravity of about 5.5, and a Young's Modulus of approximately 100GPa.

Is gallium arsenide a better, or worse choice than aluminum (our benchmark material), for an aircraft wing, based on specific stiffness alone?

<a> Better <b+> Worse

Table 1.





Mohs'Hardness




<Q11> Table 1 presents some property measurements for a series of materials, whilst Figure 1 plots the Young's modulii of these materials as a function of their specific gravities. The line OP passes through the datum point for our benchmark material: aluminum. Which of the following materials would have a superior performance index for application as an aircraft wing, where a high value of Young's modulus, and a low value of specific gravity are desirable?

<a+> Alumina Tungsten <c> Nylon <d> Copper.

LECTURE 12.2. LECTURE OUTLINE Lesson 12 Quiz Lesson 12 Quiz.

Documents

gpa slide

specific gravity

specific modulus

specific strengths

series of materials

quiz slide

specific stiffness

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