The image shows steel water pipes connected to a flange with visible rust concentrated around the joint region.

a) Using a hand drawn sketch, show the likely oxygen concentration profile in and around the corroded joint and explain how this drives the corrosion. 

b) Suggest ONE preventive design and ONE maintenance strategy that you have learned in class, that could mitigate recurrence of this corrosion under similar service conditions. Justify how your strategy addresses the underlying cause. 

In the experimental setup illustrated below, copper and cadmium electrodes are immersed in seawater and are connected by an external conductive wire. A semi-permeable membrane is positioned between the electrodes, allowing ion exchange while preventing the mixing of the individual electrolyte solutions around each electrode. Redraw the diagram and use it to help answer the questions below:

The following is the Galvanic

Series in Seawater

(a)  

(b)  

(c)  

(d)  

(e)  

A

small weather sensor is being installed in the Dandenong Ranges near Melbourne,

where it will monitor temperature and humidity and send data wirelessly every

hour. The sensor is powered by a solar panel during the day, but it needs a

battery to store energy for night-time and cloudy conditions. The battery must

be:

-

Lightweight for easy transport by field technicians

-

Reliable in Melbourne’s variable climate (cold winters, warm summers)

-

Capable of lasting through many charge/discharge cycles

-

Cost-effective over time

As

materials engineers, your role is to understand how the materials used in

batteries affect their performance, durability, and suitability for different

environments.

ANSWER THE FOLLOWING IN THE SPACE PROVIDED BELOW

(a)  

Name

and briefly describe the function of two main components of a battery, focusing

on the materials typically used for each and why they are chosen. (2 marks)

(b) 

Battery

technology is evolving rapidly, with new types such as lithium–sulfur and

lithium–air being developed for future applications. These batteries use

different materials to improve energy storage by offering higher energy

densities and lighter weights compared to traditional types.  In a short paragraph, explain how the

materials used in lithium–sulfur and lithium–air batteries differ from those in

conventional batteries like lead-acid and lithium-ion. Mention one potential

advantage and one challenge of using these future materials in real-world

applications. (3 marks)

(c)  What does cycle life mean in relation to

batteries, and why is it important for the weather sensor application in

Melbourne? (1 mark)

(d)  From a materials perspective, give one

example of how battery cycle life can be increased, and one example of a factor

that can reduce cycle life. (1 mark)

(e)  Based on the case study and your answers

above, which battery type (Lead-acid, Lithium-ion, NiMH, Lithium–sulfur, or

Lithium–air) would you recommend for the Melbourne weather sensor?

In a pressurised water nuclear reactor, we need to separate/encapsulate the nuclear fuel from the pressurised water. We do this by using tubes, which are filled with nuclear fuel pellets and then put together in a so-called fuel assembly.

a) What material is used for encapsulating nuclear fuel?

b) What are the most important properties of a material used for encapsulating nuclear fuel?

c) Materials that are in direct contact with pressurised water or steam need to be highly corrosion resistant. Describe the principle of a corrosion resistant metal/alloy.

[ANSWER IN THE TEXT BOX BELOW]

I run a business from a factory that has a roof of

dimensions 20 m by 55 m.

The average solar radiation received at my location is 5

kWhr per square metre per day on average over a year.

Answer the following questions:

(a)  

(b)  

(c)   

(d)  

Let us consider a diode (pn junction) that was fabricated by adding 4.9 x10²² P atoms per m³ to create n-type Si and 1x10²² B atoms per m³ to create the p-type Si. Calculate the electrical conductivity of the n-type side of the diode at room temperature. Express your answer in ohm-m.

Information you may need: q = 1.602 x 10^-19 Amp.sec; mobility of electrons in Si at room temperature =1400 x 10⁴ m²/(V.sec); mobility of holes in Si at room temperature = 450 x 10^-4 m²/(V.sec)

[YOU MUST UPLOAD YOUR WORKING FOR THIS QUESTION]

The wire in an outdoor electric heater, with a

resistance of 26 ohm, has a

diameter of 1.8 mm and a

length of 1.5 m. What

is the resistivity of the wire? Express your answer to 6 decimal places in

units of

A

high-voltage power line carries a current of 231 A at 220 kV over a

total line resistance of 2.0 Ω. Calculate the power loss (

Darwin receives on average 5.9 kWhr per square metre per day on average over a year.

What is the corresponding capacity factor?

Which application would benefit most from a battery with high gravimetric energy density?