Download Basics of Material - Engineering Materials - Lecture Notes and more Study notes Materials science in PDF only on Docsity!
History
c. 8000 BC - First use of Cu, in the area we presently call Iraq. Found in rock formations in the metallic state, dug up and beaten into shape, to form tools, ornaments, etc.. About this same time the first farming villages appear.
c. 5000 BC - Pottery made and Cu extracted from its ore. These two materials technologies are related. High temperatures are needed to extract metal from ore, more than just sticks of wood and an open fire. Pottery ovens, properly ventilated, provided the needed temperatures. About this same time gold was discovered, dug up out of the ground and beaten into various shapes.
c. 3500 BC - Hardening of Cu with Sn. Beginning of the Bronze Age. The alloy is considerably stronger than the pure metals.
c. 1500 BC - Production of metallic iron from its oxide ore. This requires temperatures considerably higher than extraction of Cu and requires charcoal as a reducing agent. This was first done by the Hittites in present-day Turkey. Fe has important advantages over Cu: It is much more common and cheaper. The Fe-C alloy is much harder and stronger than Cu alloys so one can produce better tools and weapons with sharper edges. Knowledge of Fe smelting was so valuable that the Hittite kings apparently restricted the export of Fe weapons and kept secret their ironworking techniques. The Iron Age led to many changes in society. With a sharp Fe axe one could chop down trees more easily for building wooden houses. This led to the deforestation of much of Europe.
c. 1200BC - Earliest quenching and tempering of steel to harden it. Steel is an alloy of Fe and C. This began in Greece. Homer refers to this process in his Odyssey, describing the blinding of Cyclops.
c. 900 BC - Hardened steel tools & weapons were in widespread use, displacing the older bronze technology.
c. 1903 - Precipitation hardening of Al, the first nano-technology. This process is often referred to as age hardening. The Wright Bros. used an alloy of Al + 8wt% Cu for the engine in their plane. Fe engines were too heavy to get off the ground. Similar Al-Cu alloys have been used extensively in the aircraft industry ever since, for the main structure and skin of the aircraft. In the literature you will often see
this discovery attributed to Alfred Wilm who published a paper on the subject in 1911 and received a patent.
The production and heat treatment of Fe-C alloys and Al-Cu alloys are among the greatest technological developments in human history. These developments have had a huge impact on society and our standard of living
Unites Many Disciplines
Materials science is one of the hottest career areas in science, but to think of it as a single career is misleading. Perhaps one reason for its popularity is that it unites applications from many scientific disciplines that contribute to the development of new materials. Chemists play a predominant role in materials science because chemistry provides information about the structure and composition of materials as well as the processes to apply and synthesize them. Materials science overlaps to a large extent with polymer science resulting in many new polymeric materials being developed in this century. Materials scientists are employed by companies whose products are made of metals, ceramics, and rubber, for example; they work in the coatings (developing new varieties of paint) and biologics industries (designing materials that are compatible with human tissues for prosthetics and implants). Other applications of materials science include studies of superconducting materials, graphite materials, integrated-circuit chips, and fuel cells. Materials science is so interdisciplinary that preparation in a number of related areas is important. "It is good to have a specialization," says Darrel Tenney, chief of the Materials Division at NASA's Langley Research Center. "But you also need to be cross-trained in a related discipline. This has been important for many years, but it is becoming critical." Good verbal and written communication skills are required since most materials scientists work in teams with people in other disciplines.
Is About Business
Many materials scientists say they were drawn to the field because they are naturally curious and always wanted to know what things were made of. "In industry, though, it is not just a question of being curious, but what you are being curious about and how it will benefit the company you work for," says
"Once you develop the formulation for a basic rubber polymer, you then have to examine how that polymer will perform as a product," she says. Factors such as molecular weight, molecular weight distribution, and ethylene content all make a difference in how the material can be processed.
"Another group in research and development handles polymerization. They make all sorts of variations in the base polymer," she says. "It's my job to assess the effect these variations will have on product performance." Part of this work includes evaluating how the material will process in machinery such as extruders and injection molders as well as in different curing applications like microwave or hot-air ovens. With her knowledge of polymer processing, Peavey is often the customer's resource for advice on how to formulate and process EPDM for a specific application.
Barry Speronello
Catalysts
"I always tinkered as a child," says Barry Speronello, an engineering fellow at Englehard Corporation. "I studied ceramic science and engineering. Now I work with catalysts. A person with materials science training can do a lot in catalysis, more than I was aware. Catalytic materials are overwhelmingly ceramic," he says.
"I really like the breadth of activities in which I get to participate. Some chemists work within a very narrow range, but with greater depth than I will ever have. I think I'm well suited for what I do because I like to take as broad a perspective as possible."
In his job, Speronello says he can conceive of a concept and work on that concept completely through commercial sales. "I determine the practicality of the concept and work with the manufacturing group to develop a manufacturing process. I work with customers and let them know how the product will enable them to do what they need to do better, faster, and cheaper. This way, I have the opportunity to shepherd my original conception through its useful life."
Bruce Scott
Films for the Semiconductor Industry
The electronics industry relies on highly specialized materials to make the components it uses in telephones, computers, and other electronic devices. Silicon is a key material in most of these components.
Bruce Scott, manager of chemistry and materials science at IBM's T. J. Watson Research Center, has spent part of his career studying the chemistry of deposition of very thin films of silicon. As a result of these studies, Scott has improved the chemical process for the fabrication of devices that are at the core of IBM's business.
Scott explains that the films are made by allowing monosilane gas to decompose on a substrate, usually also composed of a crystal form of silicon. "We spent a lot of time researching the gas phase and surface reactions that lead to the deposition of films," Scott says. "Traditionally, films are deposited at high temperatures, near 1000 C, from chlorosilanes. We studied these processes in detail to see if the same films could be formed at a lower temperature. Low-temperature deposition is important because films with sharp electrical characteristics can be made, leading to very high-speed computer circuits. This emphasis led to the development of a new process for the lower-temperature deposition of silicon films. Because we understood the chemistry and how the gas behaves, we were able to develop a completely new process technology that is now being used to manufacture devices. It is a good example of the direct transfer of basic science results to technology."
Gregg Zank
Ceramics
Gregg Zank, a senior research specialist in the advanced ceramics program at Dow Corning, has a hand in every stage of making a ceramic part. "We make molecular materials, pre-ceramic polymers, and ceramic parts for a wide range of applications," he says. One aspect of his job is to design pre-ceramic polymers that can be used in conjunction with other materials to make the highest quality and most cost-effective part. "An important aspect of this work is being able to relate the chemistry in the polymer to how it will affect the properties of the ceramic," he says.
"There is a real emphasis today on making ceramic parts that are cheaper and easier to manufacture," he says. Zank cites, as an example, parts that have a certain shape or detail that is vital to their function. "These are parts that are not just tubes but that need to have grooves and flanges on them. Being able to build a ceramic part in this kind of detail before it is sintered is the most economical way to make it," he says.
To make a ceramic part, a materials scientist blends the polymer with a ceramic powder, and this blended material is then molded in a die that incorporates the desired detail incorporate the details.
breakthrough in the science of organics will prove their worth in the marketplace." Haddon says that at Bell Labs, there is good support for basic research. "The hope is that there will be an application for every piece of basic research."
Work Description
Materials science covers a broad range of sciences. Materials scientists do fundamental research on the chemical properties of materials, develop new materials, and modify formulations of existing materials to suit new applications.
Work Environment
Some materials scientists say one of the most satisfying aspects of their work is being involved in a project from the materials' initial conception through its manufacture and marketing. Much of their work is performed in the lab, but they also work with engineers and processing specialists in pilot plants or manufacturing facilities. After a material is sold, materials scientists often help customers tailor the material to suit their needs.
Places of Employment
Most materials scientists are employed in industry where products are made; some are employed by government and academia. Many work in the electronic and computer industry.
Personal Characteristics
Most materials scientists describe themselves as curiosity-driven. They say they have always been interested in knowing what things are made of, such as the plastic in the cup they are drinking from or the components of a composite material. They also express a strong interest in engineering and structures. Most describe themselves as generalists; some say they feel their knowledge base is "a mile wide, but an inch deep."
Education and Training
The materials science field is made up of people with various educational backgrounds. Some companies are more interested in hiring Ph.D. candidates. However, most projects in materials science are team efforts, and a team can include technicians, engineers, physicists, and materials scientists with B.S. or M.S. degrees, as well as Ph.D. chemists. Students are encouraged to give thoughtful consideration to the
type of work they want to do and then investigate the level of education that is required. There are about 20 degree programs in materials science in the United States, but most materials scientists recommend training in a more specific discipline, such as inorganic synthesis and organic chemistry, or specific materials science such as ceramic engineering. They advise, however, against specializing too soon. In addition to their scientific training, materials scientists stress the importance of understanding, and the ability to apply basic statistical concepts.
Job Outlook
Materials scientists say the current job outlook continues to be good because the demand for new materials and modifications of existing materials is ongoing. Some caution, however, that materials science may become a victim of its own success. Since much of the technology developed in the past decade was so good, the growth curve for the future will flatten out. Certain areas within materials science, such as electronics, are already seeing flattening in employment growth.
Salary Information
To find out what a person in this type of position earns in your area of the country, please refer to the ACS Salary Comparator. Use of the ACS Salary Comparator is a member-only benefit. General information about salaries in chemical professions can be obtained through published survey results.
For More Information
Materials science spans so many different disciplines that people who work in this field tend to be allied with the associations or university laboratories that share their specialization. Students are urged to contact associations for ceramic manufacturers, synthetic rubber makers, paints and coatings manufacturers, and plastics makers to find out more about each of these areas and the opportunities that exist for materials chemists in each of them.
What You Can Do Now
Materials science jobs are concentrated in industry. Because of this, students investigate the corporate environment early on in their scientific career to determine if this work atmosphere suits them. Students also need to focus on their career goals to determine if they prefer a more specialized field, or whether the breadth and interdisciplinary nature of materials science will satisfy them
touch). Experimentation is intentionally acting on or manipulating something to see what happens.
- The steps of the scientific method A) are flexible; when science gets done in the real world, the steps may not be followed in order.
- What separates science from something like art or literature? C) Scientific ideas must be tested before they can be accepted, and if any test proves the idea wrong, the idea must be changed. Not so with art or music. You may not like to look at Picasso or listen to Bach, but that does not make the paintings or the music wrong.
- How does an hypothesis differ from a theory? C) An hypothesis is an educated guess. It can become a theory after is has been welltested and is not shown to be false.
- How does a scientist choose between competing hypotheses? C) He may not really have to choose; as more experiments or observations are performed, some of the competing hypotheses may be eliminated as they are shown to be false.
- Why do scientists use equations? D) Equations are a concise and convenient way to express ideas, and can be used to make precise predictions.
- Which of the following is an example of genuine science (as opposed to pseudoscience)? A) Astronomy.
- Why does Mendeleyev generally receive the credit for developing the periodic table of the elements, even though Lothar Meyer came up with almost exactly the same table at almost exactly the same time? D) Mendeleyev used his periodic table to predict the existence of previously undiscovered elements. For example, the element gallium was discovered after Mendeleyev's table indicated that an element should exist with its specific properties.
- What is energy? A) Energy is the ability to do work. Whatever work is.
- When Democritus proposed the atomic theory of matter more than 2000 years ago, he suggested that A) atoms were particles of matter too small to be seen. These atoms could not be split into smaller pieces.
- The atomic theory of matter D) is over 2000 years old; Democritus proposed the existence of atoms in about 400 BC.
- Dalton’s weight ratios, Brownian motion, and Einstein’s rates of diffusion C) are indirect evidence that is consistent with atomic theory.
- The electron was discovered C) in 1897 by J.J. Thomson, who determined that cathode ray particles were too small to be ions.
- The atomic nucleus was discovered A) in 1911 by Ernest Rutherford, who bombarded a gold foil with particles to observe their path.
- How do we know that atoms really exist? C) There is indirect evidence: Brownian motion. If that's not enough for you, there is also direct evidence: using an electron microscope, you can obtain the actual image of an atom.
- How do we know that atoms are motion? B) Diffusion: you can watch an ink drop spread through a glass of water, or smell the cookies baking.
- How did Einstein contribute to our understanding of atoms? D) He calculated rates of diffusion, which could be measured experimentally.
- What's so important about Max vonLaue and his shooting a beam of xrays at a piece of metallic foil? D) Not only did it show that atoms really exist, it also revealed that long—range order was possible, and that different metals could have different crystal structures.
- Which of the following is not true about atoms? D) If you added up the number of atoms in the universe, there would be about 117.
- Protons A) have a positive charge.
- Neutrons C) are found in the nucleus of atoms.
- Electrons B) have an extremely small mass, compared to protons or neutrons.
- Beryllium has an atomic number of 4. This means C) there are 4 protons in the nucleus.
- What is the atomic weight of In? C) 114.8. Each proton and neutron in the nucleus weighs 1amu. The weight has a decimal because some isotopes exist with more or fewer neutrons, so this number is an average value.
- Find the element titanium (Ti.) on the attached periodic table. What is the atomic number of Ti? A) 22. It has exactly 22 protons in its nucleus.
- What is the atomic weight of Ti? C) 47.87. Each proton and neutron in the nucleus weighs exactly 1amu. The weight has a decimal because some isotopes exist with more or fewer neutrons, so this number is an average value.
- Which element comes the closest to having twice the atomic weight of Ti? A) Zirconium (Zr). B) Molybdenum (Mo). C) Ruthenium (Ru). D) Technetium (Tc).
- When a hydrogen nucleus is fused with a lithium nucleus, the result is C) a beryllium nucleus.
- What is antimatter? B) Antimatter particles have the same mass, but opposite charge as particles of matter.
- What are quarks? D) Quarks are the subatomic particles that make up protons and neutrons.
- And what about dark matter? C) It’s matter that hasn’t been observed, but is predicted to exist by the effect it has on stars and galaxies. There seems to be an awful lot of it in the universe.
2 nd^ set
- Is force a scalar or vector quantity? C) Vector: the magnitude and direction of the push are independent, but both necessary to specify.
- How does the charge of an electron differ from the charge on a proton? B) The electron has a negative charge and the proton has a positive charge.
- Compare an electron to a proton. C) The electron is much less massive than the proton. The charges are equal in size, but opposite in sign.
- Every lithium atom has 3 protons in its nucleus. If one electron is added to a neutral lithium atom,
D) a negative ion is created. The net electrical charge will be -1.6x10-19C.
- To say that charge is quantized means that an object C) can only have whole number of protons or electrons, so there are specific amounts, or quanta, of charge that are allowable; you cannot have half an electron.
- Two identical spheres carry the same amount of charge. Both spheres are negative. A) The spheres will repel each other.
- Two identical spheres carry the same amount of charge. One is negative, the other positive. B) The spheres will be attracted to each other.
- To say that charge is conserved means that electrical charges D) can be moved or transferred from one object to another, but not created or destroyed.
- According to Coulomb's law, what happens to the electromagnetic force between two particles as the distance increases? A) The magnitude of the force decreases, and the direction is unchanged.
- You have two charged particles. Q1 = +3C, and Q2 = -5C separated by 10cm. Describe the force between charges. A) The force is attractive: Q1 and Q2 are each pulled toward the other.
- If the charges are moved so that the separation is now 20cm. How has the force changed? D) Doubling the distance means the force is reduced to 1/4 of its original value.
- When two charged particles are separated by 16 cm, the attractive force between them is 48N. What is the force between them if the separation is increased to 32 cm A) 3 N B) 6 N C) 12 N D) 24 N
- Compared to the force of gravity, the electrostatic force on an electron by a proton in a hydrogen atom A) is much bigger.
- Why are materials like glass or rubber good insulators? D) Insulators typically have full outermost electron shells; it is more difficult to pull an electron off, and if you manage to pull one off, the next atom over has no place to put it.
- You rub a balloon vigorously on your hair, then stick it to the wall. While you are rubbing the balloon, you are using D) friction to transfer negative charges from your hair to the balloon.
of the air pressure on Earth. B) Uh-oh. Your face will explode like a really bad special effect in a Arnold Schwarzenegger movie, because your body’s internal pressure is much greater than the external air pressure.
- Atmospheric pressure is 14.7lb/in2 at sea level. Why doesn't this make you uncomfortable? C) Your body's internal pressure matches the external air pressure. As long as the pressures are the same, you do not notice it. When your ears pop, this is your body regulating its pressure to match its environment.
- You have signed up for diving lessons at the Acme Scuba Shop. Your instructor, who looks suspiciously like he has had inhaled one lungful too many of hemp-based aromatherapy incense, tells the class that the one thing a diver must never do is exhale while ascending from a dive. D) Get your money back, he's trying to kill you. Decreasing pressure will cause the air to expand and your lungs to overinflate, which could seriously injure or even kill you.
- You buy a bag of chips at a San Francisco convenience store. You then drive to Mount Tamalpais for a picnic, where you pull the sealed packet out of your backpack. C) The packet has puffed up because the air pressure decreased when your altitude increased.
- A mercury barometer works when air pressure pushes down on an open dish of mercury, forcing some of the liquid metal up into a glass tube. A) Higher pressure means the column of mercury gets longer.
- A mercury barometer works when air pressure pushes down on a dish of mercury, forcing some of the liquid metal up into a glass tube. The higher the column of mercury, the greater the pressure of the surrounding air. B) If you replace the mercury with water, your tube must be longer.
- According to Boyle's Law, C) decreasing the volume of a gas increases the pressure.
- A closed cylinder of air has a volume of 2 liters. A piston decreases the volume to 1 liter. A) The pressure is now twice as much.
- Compared to a calm, windless day, on a windy day the barometric pressure will be B) less.
- Bernoulli’s principle states that C) a moving fluid exerts less pressure than a stationary fluid.
- One fine afternoon, Dumb decides to play a trick on Dumber. From the balcony overlooking the cafe, he drops his telescoping drinking straw 15 meters into Dumber’s coke while he is not looking. He sucks it dry and retracts the straw before Dumber turns around, astonished at his missing beverage. C) Only with CGI special effects; the straw is too long, and even a vacuum pump could not raise the liquid above 10.3 meters.
- So how does a soda straw work?
B) You reduce the pressure in the straw, causing the atmosphere to push liquid into the tube.
- How does a vacuum cleaner work? C) It reduces the pressure in the hose. The greater external air pressure pushes the dirt into the vacuum.
- You step outside on a windy day, and put up your umbrella to protect you from the rain. Suddenly, a gust of wind and the umbrella is turned inside out. B) The wind moving over the top of the umbrella exerted less pressure than the still air beneath. The still air pushed the umbrella up from below.
- You place a ping-pong ball in a funnel and challenge your little brother to blow it out. C) The moving air beneath the ball reduce the pressure below it, so the air pushes down harder on the top of the ball, keeping it in place. The harder he blows, the more the ball is pushed into the funnel!
4 th^ Set
PHYS 1400 Sample Exams: Heat Transfer
- How do we know that heat is a form of energy, and not some mysterious fluid? B) Heat must be energy, because you don't have to burn something to produce heat: friction produces heat. When you rub your hands together, friction warms them. As soon as you stop rubbing, the heat goes away.
- Two metal bars are brought into contact, end to end. One bar has a temperature of 0°C, and the other is at 50°C. C) The hot bar transfers heat to the cold one until both reach a final temperature between 0°
- Radiation is A) the transmission of energy without the need for a medium of transfer.
- The frequency of the radiant energy emitted by an object is B) directly proportional to the temperature of the object: lower frequency means lower temperature.
- For a top-secret CIA mission, Marshall develops an “invisible suit” for agent Sydney Bristow. To avoid detection by infrared surveillance, the suit is designed to radiate at the same temperature as the surrounding environment, about 70°F. B) Unless the suit is equipped with a portable and detachable heat sink to absorb her excess body heat, she won’t be able to gather much intelligence--she’ll be too busy having a heatstroke.
- An object appears black because it is B) a good absorber of radiation.
- Clear nights will tend to be colder than cloudy nights at the same time of year. A) This is because clouds will prevent the earth’s heat from radiating back into space.
- Why do you see signs posted, “Caution: Watch for Ice on Bridge”? Shouldn’t you be looking for ice on the road as well? B) The bridge will ice first, because it doesn’t make contact with the earth. The road actually stays warmer longer, since heat is conducted from the warmer earth below.
- The rate at which an object cools is A) directly proportional to the change in temperature: the greater the temperature difference, the faster the rate of cooling.
- Two delicious bowls of Campbell’s cream of tomato soup are placed on the table. One bowl is piping hot, at 80°C. The other bowl is lukewarm, at 50°C. B) The hotter bowl will cool more quickly, but since it has more heat to begin with, may still take longer to reach room temperature.
- To keep your freshly brewed coffee as hot as possible for as long as possible, A) add the cream as soon as the coffee is poured.
- Which of the following is a violation of the law of mass conservation? E) You "accidentally" zap your kids with an atomic ray, and they all become ¼ inch tall. You "mistakenly" throw them in the trash, and hilarious adventures ensue.
- Which of the following is not allowed by the law of energy conservation? D) Energy can be created or destroyed; i.e., when a bowling ball rolls across a carpet and slows down, its kinetic energy is completely destroyed.
- How are potential and kinetic energy different? E) Potential energy is stored energy. Kinetic energy is energy of motion.
- Kinetic energy is defined using the equation K = ½mv2. Can kinetic energy be negative? C) K can only be positive: m cannot be negative, and v is squared, so it must also be positive.
- Which of the following is not an example of potential energy? E) You paint the living room walls. As the paint dries, the kinetic energy of the paint molecules is converted to pigment potential. This is why paint always dries a slightly darker color.
- How much of the sun's energy reaches the earth's surface? B) Less than half of it.
- Why don't you see more houses with solar panels on the roof? D) Because they are expensive, and electricity is still relatively cheap. Americans generally don't see the value in an investment that may take several years to show any positive return.
- What happens to all that solar energy that does not get turned into useable electricity? C) Even if it does not get turned into electricity, the energy gets used. Plants use it directly to convert the CO2 in the atmosphere to oxygen.
- Explain the idea of a trophic level. D) The concept is related to energy. Organisms at any given trophic level get their energy from the same type of source. For example, herbivores don't all eat exactly the same thing, but they all eat the same sort of thing: plants.
- On a global scale, why are there so many more plants than panthers? D) There are more plants because they occupy the lowest trophic level, which means they use the available energy (sunlight) most efficiently and can exist in greater numbers. panthers have to get their energy from eating other animals, which is less efficient. So there are fewer of them.
- You are thinking about doing a study on global warming for your Honor's Thesis. The more research you do, the more complicated the problem seems to be! To try to simplify the problem, you decide to start by looking at the Earth as a whole. Define your system. B) Earth is an open system: both matter and energy can be moved into or out of the system.
