Materials Engineering

Okay, so, this course is a basically a Material Science course, aimed at giving you some basic

understanding of materials because that forms the fundamental basis for several aspects

of study in mechanical engineering. And, and hence this course is one of the foundational

courses, is extremely important for you if you want to be a good mechanical engineer.

And, so let me ask you this question. What is your first impression when you have heard

of the title of this course? Whether it is going to be a boring course or an exciting

course? You can be honest. First first class I do not remember any of you. So, you can

be brutally honest. . Lots of theory to remember. Yeah? Sir, lot of . Lot of mugging up required. Yeah.

Probably, yeah. How many of you think there is lot of mugging up required? Very good.

. Why the others do not think there is lot of mugging up required? . Or others never thought anything about it? Yeah, both are possible, right? So, we will

see whether there is lot of mugging up required for you in this course or not and we will

comment on that in a moment, ok? So, my name is Ratna Kumar. I sit in Machine

Design Section. So, books for this course, the main textbook for this course is Callister's

Materials Science and Engineering, ok? And this course has several sub-sections or several

topics. The primary textbook will be Materials Science and Engineering, and we will have

another section on failure theories. For failure theories alone we will use the textbook of Machine Design by Robert L. Norton or Shigley's; Shigley's Mechanical Engineering

Design -- one of these textbooks. For phase diagrams, which is the last topic -- for that

particular section we will use Dieter's Introduction to Physical Metallurgy or Reed-Hill's Principles

of Physical Metallurgy, right right? You are also encouraged to go through these

additional readings -- Mechanical Metallurgy by George Dieter, and Engineering Materials

1 and 2, two volumes by Michael Ashby. They are really, particularly the last book is

a wonderful book for you to gain have some understanding of what materials can do and

how they are placed in the development of engineering in general, and mechanical engineering in particular, okay? So, in your free time you can actually go

through that textbook if you are interested, alright? And, there are several copies of

this book available in the library. This particular textbook. And, this book also is available

in the library. This is available. This is available. This is also available. This -- not

many textbooks, few copies are available of the last textbook. So, what are the contents of this course? The details are given in your course portfolio

for each and every chapter and each and every section. So, the first we will start with structure-property correlations, wherein, we study how the structure of the material

leads to different kinds of properties that may be needed for designing components as

a mechanical engineer. And, so, here the part of that we will study

crystal structure, defects in materials, and how the crystal structure and the defects lead to different kinds of mechanical behavior of engineering materials. And we will talk

about different properties tensile property tensile behavior, compression behavior and different kinds of loading onto the materials, and we will see how to measure certain properties

of the materials. So, that is sort of the first part of this

course. Having learnt the mechanical properties of the materials, now we can use these mechanical

properties to actually design components, ok? So, there we will talk about failure theories,

both static and dynamic failure theories, which will be used for design, and then we

will talk about phase diagrams. You may have some overlap between this course

and manufacturing technology or manufacturing processes. Which course are you taking? Manufacturing technology? Processes? So, in the manufacturing processes also they

will teach phase diagrams and heat treatments of steels -- heat treatment of steels. But here, we will spend a little bit more time on phase diagrams to understand them in detail,

and of course, heat treatment of steels, ok? That is the total content that we will be

trying to uncover during this course, ok? So, as I mentioned, the course portfolio has

learning outcomes. We have listed the learning outcomes for each topic, each subtopic, and

we have written -- we have identified the chapters in the relevant textbook from which

this material will be taught. So, you are required to read those textbooks and try to

see if you are able to -- if you are at the end of reading, or at the end of the lecture

you should have achieved these, or attained these learning outcomes, right? So, each lecture that we are going to have in the subsequent classes is designed around

these learning outcomes that are mentioned in the course portfolio. So, it is extremely important that you refer to this course portfolio from time to time,

so that you can be sure whether you have achieved the learning outcomes or not, ok? Please note

that the lecture slides cannot substitute for a textbook, you are required to read a

textbook, right? So, how many of you have the habit of reading novels? Yeah? So, can you experience the difference between reading a novel, and if the same novel

is filmed as a movie? Yeah? When you are reading a novel, you actually participate. You walk

along with the characters. You actually become part of the story and you construct the scenes, right? Instead of somebody -- screenplay writer, or a director

constructing scenes for you, you construct scenes. That is much more enjoyable rather

than watching it once -- the scenes constructed by somebody else, right?

The same experience you will have if you read a textbook. You can listen to the lecture,

but even if you do not listen to the lecture, if you read a textbook you can actually master

the course, ok? There are certain concepts which may not be easy to comprehend. So, those

concepts you can get clarified in the class, but otherwise listening to the lecture can

substitute -- cannot substitute reading a textbook, ok? So, please make it a habit to

read the textbook. And, not only textbooks, you also are required to read additional materials. So, the way that we are going to design question papers

and tutorials is the following -- 40 percent will be recall type.

So, if you are paying attention in the class and you are listening to me properly and going

back and referring to the textbook or slides once -- after the class, you should be able

to get 40 percent of the marks -- that means, you should be able to pass test and remaining

40 percent is based on analysis and problem-solving. So, you should be able to apply, application

of the knowledge that you have gained during the class. So, that comes by practice. If you practice well, you should be able to answer those 40 percent. They are not necessarily

difficult, they are just application of the concept that you have learned in the class, but the remaining 20 percent is going to be difficult.

So, they can be ranging from moderately difficult to extremely difficult. So, if you are able

to answer this 20 percent, only then you will be able to get S grade, otherwise it is not

possible, ok? So, you decide which grade you want, and you work towards that, alright?

Now, what is material science, and why should we know about it? These are the two questions

as a mechanical engineer, what is there in it for me? Why should I spend 9 hours per

week breaking my head rather than chilling out on learning material science as a mechanical

engineer? Right? This is the question that we need to ask ourselves to see the value of this subject in the grand plan of mechanical engineering, and we will

try to answer this question through the lectures that we have in this class. So, why should we know about it? So, almost every part of our life is directly dependent

on materials, no matter whatever aspect of life that you take, it is dependent on materials

right. For instance, food -- preparation of food. How will you make food? How will you

cook? You have rice or dal or wheat, in the end you cannot eat the raw material you need

to cook, right? -- or you need to prepare. So, in order to prepare food, you need to

have some processing, right? How do you do this processing? So, let us

say somebody else has done the processing and the rice came to your house, then what will you do with the rice? You need to cook, right? So, how will you cook? First of all,

you need to have a pot. The pot should be made of a material, right?

So, you should know what kind of a material I want to use, depending upon your financial

situation or your liking, you decide which kind of a pot you want to buy, and then you

cook the food, right? So, the basis is even if you want to cook at all you need some material, right? Coming to shelter -- housing, you need building materials,

clothing, transportation, communication, entertainment. No matter what aspect of life that you take

into consideration, their realization depends on the existence of materials -- appropriate

materials for that particular purpose, right? For instance, if you want to have a mobile

phone, you cannot have a mobile phone unless you have an integrated circuit. You cannot have an integrated circuit unless you have the base materials such as silicon, right?

So, in that sense materials forms the basis for every walk of our life, right?

So, you can see the impact of materials on our civilization just by looking at

the way that we have looked at civilization -- classified civilization, right? How did we classify civilization? .

We talk about different ages, right? What ages are we talking about? What is the first

age? Louder. Stone age. Stone age. Why did we call it as stone age?

. Because all the instruments during that time, all the weapons that they use to hunting all are made of stones, stone is a material, right?

So, the material that is dominating that particular era has become the name of the era, right?

So, that is why you have stone age, then bronze age, iron age and then you have modern materials

age, right? What are those modern -- modern materials -- materials? Plastics? We have

seen the development of plastic, right? . So, maybe more -- most of you were not born when the plastic revolution has started, right?

All of you are 1990s guys? 90s? Late 90s, right?

. Yeah. . 2000s right not even 90s, yeah? So, you have

-- you have not seen the plastic revolution shaping up, right? So, there were no water

bottles, pet bottles when I was a kid. We used to carry water bottle with us, and in

each and every train station, we used to get down and fill in the bottle. Now, we do not

do that, right? We sit in our seat and we buy the water bottle in pet cans. So, you cannot imagine the amount of change that brought to the comfort of human beings

from the day when we did not have access to such materials to the days that we have access to such materials. So, I am only giving you a -- a simple example that we are familiar

with, but take -- take into account of the medical industry, right? -- surgical instruments,

right? So, when plastic was not prominent -- how many of you have taken injection with

a glass syringe? Have you ever taken an injection with a glass syringe? You do not remember, right? So, when the plastic syringes were not there, syringes

were made of glass, and every time you give any shot what you do is you actually boil

the syringe, so that it is -- that means, you are sterilizing the syringe for the next

shot. And now, you do not do that, right? What do we do? You buy for 10 rupees one plastic

syringe, and then give a shot and throw it away, right? So, the comfort levels have increased significantly. And then, of course, silicon age and plastic

age they are not one after the other and that is not the meaning that I have here. It is also the modern materials age you can see what silicon did to us, right?

. So, silicon did so much that we stopped talking to each other, we start talking to phones -- through phones to each other, right?

And then, now we are moving towards - we are going beyond silicon age, and then we are

moving towards design materials age. So, we are now talking about -- can we design materials

the way that we want, and then get the output the way that we want, right? So, there are

several examples. So, I would encourage you to go back and Google these terms, and then you will see excellent articles and videos on these these particular

topics. For instance, molecular self-assembly, hierarchical structures, smart materials, meta materials -- these are all the new age materials that we need to focus on, and there

is lot of R and D money spent on these aspects, which is going to revolutionize the way that

we see the world today, right? So, may be when you become a professor, if

at all you want to, and 20 years later you may say that we never heard of -- we only

were thinking of these devices that can be made of molecular self-assembly -- they are in their infancy and today they are everywhere, right? You may say something like that to

your students, like I am telling you about the plastic to you guys. Okay, so, what is the role of materials in our human life? In order to talk about it,

just think of major challenges that we face today. What are the major challenges that we are facing today? What are the problems that we have? Are you aware of any problems

that we are have -- we have today? . Louder. Water.

Water, ok. He has problems with water ok, that is all?

. This helps you wake up if you are sleeping. . Global warming, very good. Clean form of energy. Clean form of energy, very good. So, clean

energy is the -- one of the important aspects. Everybody talks about clean energy, right?

Clean water, portable water, healthcare -- access to everybody -- not everyone has equal access

to good healthcare, right? If you have money, you can have access to good healthcare, but

if you do not have money, you probably do not have access to good healthcare, right?

And infrastructure, and sustainable environment. So, these are the challenges that we need

to address. And, materials play a central role in solving

these challenges or solving these problems or addressing these problems. The development of new materials, new kinds of materials, new kinds of material processes is going to

help you address several of these problems, and many of you may be in the forefront of

solving these problems in future, right? And, you will realize that somebody elsewhere

developing a new class of material, is going to change the way that you are probably designing

a product or conceiving a product and so on, right?

So, you can actually think of the computers, right? So, the way the computers have been

miniaturized, from the first-generation computers to the mobile phones you have today, right?

-- because of the development of new technologies and new materials that we have today. Alright. So, how about clean energy? What do you -- what are are the issues with the

clean energy? Main problem is you have a lot of thermal coal-based energy, right? What

is the problem with coal-based energy? . Lot of pollution, right? So, you cannot get rid of coal-based energy at all. You cannot

say that ok today I am going to shut down all my thermal power plants. I am only going to rely on renewable sources of energy. Then you probably should stop using, or you probably

start accepting huge power cuts, once an hour per day availability of power, right? Because

thermal power is -- the fraction of thermal power is significant in our economy, right? We cannot simply stop them. Rather what we should do is, we should try to make that energy

a clean energy. That means, you we need to reduce the pollution that is coming from these

energy sources. So, efficient combustion processes like -- if you are burning coal you need to

burn coal in a better manner, so that you reduce the pollutants.

And, if you are going for solar energy -- so, even today solar energy has several issues.

What are those issues? Particularly the efficiency, the kind of materials that you have. The efficiency

values are not really encouraging today, but if you have new kind of materials which can

enhance the photovoltaic efficiency for solar panels, that can reduce the energy production

costs significantly. If you reduce the energy production costs, then probably one day you will be able to get rid of thermal power. But then it comes with some problems, right?

So, you now if you want to create a solar power plant you need to have lot of land area,

right? And it should depending on -- it should be depending on the light -- sunlight. So, these are the issues that you need to work around. But the main issue is if you

are able to come up with new kind of materials, you can actually enhance their efficiency,

and hence probably increase the fraction of solar energy that we have in our economy,

right? And, wind turbines -- again, the materials that are used for making these wind turbine blades needs significant improvement. So,

there are different kinds of composites that are used which reduces the weight of these things, and at the same time increases the strength of the blades. This is another area.

So, that means, there is a need for new kind of material design there. And, you must have heard about lithium ion batteries, right? All of you have at least one lithium ion battery

with you -- do you have? -- right? . At least one, if not more. The problem again is the energy density, right? How much energy

that you can store per unit volume of this lithium. So, if you can increase the energy

density of these materials, and efficiency of these materials -- lithium ion batteries -- then you can actually use these batteries for longer time, and you can reduce the losses.

So, that means, you need to invent new materials, and understand the behavior of these materials,

or you need to minimize the failures in lithium ion batteries. Sometime back you probably heard of batteries exploding, right? -- overheating. So, as an engineer you need to understand

what is the cause for this overheating, and how can you circumvent these problems, right? So, it involves lot of money, right? If you are designing a battery and which produces

a lot of heat and your customers are not going to be happy and they are going to return the product and causes lot of money. So, you need to understand as an engineer what are the

causes and see if we can fix these issues, right?

And, even if you are going to live with your thermal power for instance -- today people

are talking about super-critical boilers, wherein you increase the temperature at which

you are running your turbines, right? If you are increasing the temperature at which you are running your turbine, what happens? What is the advantage? How many of you have taken

thermodynamics course? Right? How can you increase the Carnot efficiency?

There is a source temperature and sink temperature, right? What are the different ways that you can increase the Carnot efficiency? .

Either increase the source temperature or decrease the? Sink temperature. Sink temperature, right? So, that means, in

-- analogously for a steam turbine, if you increase the temperature at which your turbine

can operate, you are sort of increasing the distance between source and sink. That means, you are going to increase your thermal efficiency. But the problem is the materials cannot withstand

such high temperatures, right? The current materials that we have, are not able to withstand

such high temperatures, they will fail quickly. So, now, you need to develop new kind of materials,

new alloys which can withstand these high temperatures, so that you can increase your thermal efficiency. Why do you need to increase thermal efficiency? So that you can burn less

coal for getting same amount of energy, right? Right.

Another important area of study for clean energy is hydrogen as the source of energy,

because it will not -- it is a carbon zero source of energy, right? Recently you probably have seen LinkedIn posts or Facebook posts from IIT Madras, that one

lab has developed a better way to produce hydrogen -- extract hydrogen, right? So, people

are working on developing -- extracting hydrogen at minimal cost because that is going to change

the way that we are going to work with energy. You can completely get rid of carbon based

pollutants, right? It is cleanest form of energy that we can think of. Alright.

Then clean water, of course, you need to have better materials for water purification, right? All of you must have had a water purifier at home or at least you have it -- you have

one in your hostels, or you have purified water in your hostel, right? So, you need

to have better materials which can reduce the cost of purification, right? If you can reduce the cost of purification, then it saves lot of energy again.

So, in some sense energy is going to influence every other technological invention that we

are going to make, ok? And, health care -- biodegradable materials for implants, right? -- disposable

materials for surgeries -- and how can we minimize hazardous healthcare waste, right?

So, just now we have discussed -- we use the syringes for taking shot and we just dispose

them. And do you know how much time does it take for one plastic syringe that you are

we are disposing off to decompose? Do you know how much time does it take for a banana

peel to decompose? The skin -- banana skin you peel off and throw away, right?

Right. And, it decomposes or not? It does decompose, right? How many days does it take? Couple of weeks? Yeah? How many days does it take

for -- for instance a cigarette bud to decompose? Have you thought about it?

. Please go back and Google the time for decomposition

of different materials, ok? And then you will see why we have problem with plastic today,

ok? And that is the -- and you will understand the reason why the government has banned usage

of one time use plastics, right? So, next time when you go to a restaurant,

ask them to give you steel cutlery, rather than giving you a plastic cutlery. Do not

request plastic cutlery from Zomato and Swiggy. Say I do not want cutlery, yeah? -- after

Googling, and you will realize what -- what we are doing by saying do not want to cutlery

-- plastic cutlery, ok? Alright. So, we also need to deal -- develop new methodologies

to deal with new epidemics, and develop new medical devices, right? Alright. And, for

infrastructure, you need have better housing. So, you need to have better material. So,

for instance, if you are in a cold country, you need to ensure that your house -- housing

material is good enough for safeguarding you from extreme cold. So, that means, the thermal conductivity -- it should be a good insulator, right? -- so that

you can you can minimize the heating costs. You will have a heater in the house, but if

you do not have a good insulating building material your heating cost will go up, right?

So, your building material should be reasonably good enough, right? And you need to think

about developing buildings which actually produce energy rather than consume energy,

right? So, people are now talking about green buildings. So, carbon negative buildings;

that means, they actually would not produce -- would not consume energy, they will have a net negative consumption of energy. The building itself generates energy by using

solar panels and so on, right? The new kind of materials that one needs to

develop, and then that leads to a significant reduction in energy costs. And of course,

communication -- how can you reduce the energy costs through communication, right? Have you

ever thought about posting an image in FB, Facebook? Does it cost energy? How?

. Which generates heat? . Yeah. For every image that you are posting

on FB, they are not storing actually on one server, but they are storing on several data

servers, ok? So, if you keep on increasing the number of posts, then you are actually

increasing the overhead on the servers, and you are actually causing global warming. So,

posting a message can also cause global warming, right. So, you should be responsible then.

. Right. So, can you think of materials that changed history? Can you name? .

Louder. Plastics. Plastics. Plastic is the only thing that changed history?

Iron. Iron. . Quick. Quicker. . Concrete.

. Aluminum -- so, metals. So, then he says -- one

person said iron, another person said aluminum, then you will start reading all the elements in periodic table. .

Silicon, very good. Bronze. Bronze. Carbon.

Carbon, yeah. . Go ahead. Carbon .

Carbon fiber ok, very good. Go ahead. Glass.

Glass. You are sitting on? Wood. Wood. Wood, ceramics. You never bothered about talking about this, yeah?

. And, none of you said. . Yeah, we have spent almost 15 - 16 years of

your life with that and you forgot -- and semiconductors, right? These have changed

the way that world operates, and new materials are going to change the way the world is going

to operate, alright? So, we cannot imagine how the future is going to be, -- depending

on -- so, because we do not know what kind of new materials that are going to come out,

right? Yes. Okay, so, with that I will stop.