1. a) Make sketches to differentiate between microstructures in castings generated by homogeneous and by heterogeneous nucleation. What sort of structures provide the best mechanical properties?

b) For a simple binary alloy exhibiting complete solid solubility, describe how a typical composition will solidify from the moltern state. What is coring and what would encourage such an alloy to be cored? Can coring happen in alloys exhibiting an eutectic reaction?

Design fins/convection enviornment to remove 27 W/cm² from a square copper surface (50x 50 cm) while keeping the surface at a temperature of 80^oC or below. The convection environment has a bulk temperature of 20^oC. (neglect any contact resistance between the surface and the fins)

Explain why glass fiber are very strong in tension and bulk glass generally is not.

Give an example of a stress state where Mohrs circle degenerates to a point.

QUESTION 1

In the case of arbitrary planar curvilinear motion the best choice for coordinate system is tangential-normal system

QUESTION 2

Tangential coordinate axis is selected so that its positive direction is in the direction of motion of particle

QUESTION 3

Normal coordinate is selected so that its positive direction is in

QUESTION 4

Normal acceleration is

QUESTION 5

Particle moves along curvilinear path with velocity of 30 mi/h. If the radius of curvature at position P is 1,500 ft, what is normal acceleration of the particle at position P in [ft/s²]?

Name or describe in some detail a technique that can be used to determine the elemental composition of surfaces. YOU SHOULD mention one technique and write more details about it

Manufacturing Process

list the similarities and differences between direct extrusion and drawing.

From the expressions we derived for the kinetic theory of gases, it can be shown that the fraction of gas molecules having speeds in excess of a particular speed c is

f(c) = 1 + [2*alpha/sqrt(pi)] exp(-alpha²) - erf(alpha)

where alpha = c/c_m , c_m is the most probable speed and erf() is the error function. Consider now 1000 H₂ atoms in thermal equilibrium at 0^oC. Consider the range of speeds from 0 to 3,000 m/s divided into 100 m/s intervals.

(a) Usint the equation above, plot the number of molecules in each increment

(b) Also, on your plot, show c_m, c bar (average speed), and c_rms (rms speed)

A cast aluminium-silicon alloy containing 12 % silicon which cannot be age hardened would normally solidify with a hyper-eutectic structure. This alloy can be used for both sandcasting and metal die-casting. Describe THREE methods in which the cast metal can be strengthened by controlling the microstructure during solidification.

Natural gas consists of a mixture of several gases. One example is 84% methane, 14.8 ethane, 0.7% carbon dioxide and 0.50% nitrogen by volume. Calculate the specific heats, the molecular weight and the k value of the mixture

Write the lay-up in proper composite lay-up notation. 45 Fabric (fiberglass); 0 (Carbon fabric); 0 Tape (Carbon); 0 Tape (Carbon); 90 Tape (Carbon); +45 Tape (Carbon); -45 Tape (Carbon); +45 Fabric (Carbon); -45 Fabric (Carbon); -45 Tape (Carbon); +45 Tape (Carbon); 0 Tape (Carbon); 0 Tape (Carbon); 0 (Carbon fabric); 45 Fabric (fiberglass);

State the Bragg’s law and how it is used for X-ray analysis.

State the advantages of the field-emission electron gun over the tungsten electron gun.

State the functions of electromagnetic lenses in an SEM/EPMA.

If you have a piece of rock sample in dimensions of 10 ´ 10 ´ 10 mm³, briefly state how to prepare it for the EPMA studies.

When your rock sample is prepared, state what information you can get using the EPMA instrument.

Subject: Heat exchanger Lab

Question:

1.1) in heat exchanger analysis, the following quantities are used. Explain what each means and give
a formula for each. Assume the mass flow rates, fluid properties, inlet, temperatures, and length
and diameters of the heat exchanger are known.

a) Overall heat transfer coefficient. UA.

b) A number of transfer units, NTU.

c) Effectiveness, e

1.2) what is the hydraulic diameter and why is it useful for double-pipe heat exchanger analysis?

1. (a) Outline the principles and essential differences between Continuous Cooling Transformation and Isothermal Transformation Diagrams

   (b) Using the TTT diagram for a plain carbon steel with 0.53%wt C, define the nature of the final microstructure (in terms of micro-constituents present and approximate percentages) of small samples (5 x 5 x 5 mm) subjected to the following time-temperature heat treatments.In each case, assume that the specimen was austenitised at 860?C and held at this temperature long enough to achieve a homogeneous austenitic structure prior to cooling.

(i) Rapidly cool to 500^oC, hold for 7s, rapidly cool to 400oC, hold for 103s and water quench to room temperature.

(ii) Rapidly cool to 400^oC, hold for 7s and water quench to room temperature.

(iii) Rapid cooling to room temperature within 1s.

(iv) Rapidly cool to 650^oC, hold for 1h and water quench to room temperature.

(v) Rapidly cool to 400^oC, hold for 1s, followed by water quenching to room temperature.