materials science

Fiberglass

Fiberglass is another composite you may be familiar with. Glass fibers are very strong, but not very flexible. These fibers are bound together with plastic resin, a highly flexible material. The combination creates a material that is both flexible and strong. Fiberglass is used in boats, skis, insulation, and automobiles.

Limit use

Plastic has replaced other materials that were once used for many common items. Simply by returning to these previous materials, we can limit the amount of plastics that end up in the garbage. Paper wrappers can replace many plastics. Using paper bags and milk cartons are two easy changes we can make.

More mechanical properties

Plasticity: Materials with high plasticity can be shaped into a new form under pressure. Ductility: Materials that are ductile can be worked or formed without rupturing. Hardness: Materials that are hard have a high resistance to scratching. Diamonds are the hardest materials known. Hard materials usually have a high resistance to wear. In general, metals and ceramic materials are harder than wood and plastic.

Elastomers

Plastics called elastomers can be stretched to twice their normal length, then return to normal length when released. Both natural and synthetic rubbers are elastomers.

Polymers

Polymers are large, organic molecules sometimes called macromolecules. These macromolecules are made up of long chains of monomers. The type of bonding between these chains determines the physical attributes of the polymer. Scientists are hoping to learn how to manipulate these bonds to control specific properties of polymers. This may lead to the manufacture of products that are more durable and less costly.

porosity

Porosity describes how much air or water a product will absorb. Many porous materials allow water and air to pass through them. Think of the filter in your air conditioner. It allows air to pass through as it catches particles in the air. A sponge is an example of a material that absorbs water.

Biodegradable plastic

At present, a few biodegradable plastic products are available. Some packing peanuts and plastic bags dissolve in water. These are made by mixing polyethylene with a material similar to cornstarch. If these plastic products are buried in a landfill, they degrade in four or five years.

Building blocks

Atoms are made of basic building blocks called electrons, protons, and neutrons. The center of the atom is called the nucleus and is made up of protons and neutrons. Protons have a positive charge. Neutrons are neutral particles; they have neither a negative nor positive charge. The protons and neutrons provide most of the mass of an atom.

Ionic bonding

Atoms bond in three primary ways: Ionic bonding Covalent bonding Metallic bonding Ionic bonding occurs when atoms with opposite electrical charges come together. However, with engineering materials, covalent and metallic bonds are most important.

Detailed drawings

Before a product can go into production, detailed drawings of every part must be completed. These drawings usually include several views of a part. For products that have multiple parts, assembly drawings are needed. These drawings show how to put parts together to make the final product. Schematic drawings that provide information about the electrical, mechanical, hydraulic, and pneumatic systems are necessary for some products.

Nickel silver

Copper is alloyed with zinc and silver to make nickel silvers. This alloy is generally about 70 percent copper and 5 to 30 percent silver. The balance of the material is zinc. If you have silver-plated jewelry or forks, the base metal is probably this alloy. Nickel silvers also are used for electrical connectors and boat parts.

outputs

The baked chocolate chip cookie is the output of the system. This edible alloy can be crisp or hard, depending on the inputs and processes.

Better Materials

The dendritic microstructure of a solid material determines the material's toughness, strength, and resistance to corrosion. Scientists study these dendrite structures to understand how to manipulate a material's properties. At NASA, the growth of dendrites in space is being studied in an ongoing program called the Isothermal Dendritic Growth Experiment. The information scientists gather will enable them to create new metal alloys that may solve some of the materials problems we have on Earth.

Electrons and electricity

The flow of electricity depends on the movement of electrons in an atom's outer shell. Plastics, ceramics, and woods are usually resistors. Since these materials have no free electrons in their outer shell, electrons don't move and no electricity is produced. On the other hand, metals such as copper and aluminum have many free electrons that can move in their outer shell. If these electrons are moved with a magnetic field or chemical action, the result is moving electrons, or electricity.

Thermosets

Thermosets have many cross-linked polymer chains. These plastics become set by using heat or chemicals. After they're set, they resist heat. The handles on cookware are made from this type of plastic.

Inputs

These requirements direct the system inputs. Flour is the main ingredient in chocolate chip cookies, so we can look at a chocolate chip cookie as an edible flour alloy. Yet flour by itself won't make an edible alloy. Other ingredients like eggs, butter, and liquid are required to bind the flour. The customer wants a chocolate chip edible alloy, not just a plain edible alloy. So we need to add bits of chocolate and sugar also.

The bicycle:A system

A bicycle is also a system. You push the pedals with your feet, which provides the input--energy. The movement of the pedals causes the gears on the chain to move, which causes the back wheel to move. These are the processes. The bicycle moves forward, which is the output. The speed at which you're moving provides the feedback to the system. All these parts working together help the system to reach the goal: move down the street at a safe speed.

medium carbon steels

A carbon content between .30 percent and .55 percent places steel in the medium carbon category. Medium carbons can be casehardened (a thin layer is hardened) by heat treatment. These steels are widely used in the automotive and agricultural equipment industries.

Mechanical fastening

A mechanical fastener is any device that holds two or more parts in a specific position. Fasteners are often developed for special applications. So there is an unlimited number of possible types of fasteners. Mechanical fasteners can be either permanent or temporary. Permanent fasteners are designed to stay in place for the life of the manufactured product. Temporary fasteners are used to hold parts in place while they're being assembled.

Renewable resource

A renewable resource can be replaced. Examples of renewable resources are living, growing things such as trees, plants, and animals. When a tree is cut, another can be planted. We harvest cotton or flax for linen, then replant the next season.

Systems thinking

A system is a group of parts or persons that work together to accomplish a task or goal. All systems have five basic parts: Inputs: the resources needed to make the system work Processes: the actions taken on the inputs that make the system work Outputs: the results of the processes acting upon the inputs Feedback: the information a system uses to control itself Goals: the purpose of the system A systems approach is a method that can be used to analyze almost anything.

Bronze age

About 5,000 years ago, the Bronze Age began. People learned to use copper and to make high-quality pottery during the Bronze Age. Perhaps, copper was discovered in a fire pit. High heat from the coals melted copper ore in the rust colored rock, creating pure copper. Copper items were first formed by hammering. Eventually, people melted the ore and cast copper in sand molds. Later, molds made from stone or baked clay were used.

iron age

About the time of the Roman Empire, iron began to replace bronze as the basic material for tools. In the Iron Age, people began to specialize in particular tasks. Some became shoemakers, tailors, or butchers. They bartered what they made for what they needed. For example, a butcher might trade meat to a baker for bread. This was the beginning of manufacturing--making goods for someone else.

More ceramics

Abrasives are used to smooth surfaces. Sandpaper is an abrasive you may have used. Small, sharp, ceramic particles are attached to the paper. Glass is a ceramic made from fusing sand. Glass is easily shaped when heated. It's used for many products such as windows, mirrors, drinking glasses, and containers. Porcelain enamel is used to coat the inside of ovens. It's also used in chemical and electrical applications.

Industrial Revolution

After tradespeople emerged, materials processing and manufacturing didn't change very much until about 200 years ago. In the late 1770s, machines replaced hand tools. Engines and waterpower systems sped up the manufacturing process. Large numbers of workers were employed in factories instead of in small shops or homes. This period is called the Industrial Revolution.

Two categories of metals

All metals are one of two types: Ferrous: those with iron as the main ingredient Nonferrous: those in which iron is not a main ingredient

cotton

Although cotton was used for centuries throughout the world, it was the last natural fiber to attain commercial importance. With the invention of the cotton gin by Eli Whitney in 1793, cotton became the most important fiber because of its abundance, cost, and usefulness.

Pure metal or alloy

Although pure metals have a wide range of physical and mechanical properties, they're seldom used in a pure state. Instead, they're usually combined with other metals or inorganic materials to form an alloy. These alloys are new materials that can be engineered to fit the specific needs of a product.

Aluminum ore processing

Aluminum ore, called bauxite, is processed in two steps. First, it is processed with chemicals to produce alumina or aluminum oxide. The oxide is then electrolytically treated to produce pure aluminum from the oxide.

Bronze

Bronze doesn't have zinc or nickel as a main alloying element. Instead, it uses a mixture of copper and sometimes tin or aluminum. Bronze is sometimes used as a bonding material. Look in your local park for a large statue--it's probably made from bronze.

most common polymer

Can you guess which natural polymer is the most common engineering material? It's wood, a term that is applied to any material obtained from trees. Wood is made up of cellulose fibers, which account for about 70 percent of the volume. These fibers are held together by lignin--nature's glue. Lignin, along with small quantities of extracts and minerals, makes up the remaining 30 percent of the volume of wood.

Casting and molding

Casting and molding processes are used with most metals, ceramics, and plastics. Each material uses the same basic steps. First, the material is made into a liquid and poured or forced into a mold. Then, after the material solidifies, it is removed from the mold. The shape of the material changes, but the weight remains the same.

new fabrics

Chemical Engineers and plastics engineers have developed amazing new synthetic fibers in the last few years. Fabrics that keep you cool and are odor-resistant and wrinkle-resistant are being used in clothing. These fabrics cool body-core temperatures by pulling perspiration away from the body. This makes them ideal for sportswear.Other fibers derived from recycled plastic bottles have a unique construction. Clothing manufactured from these fibers is comfortable, resists stains, and maintains its shape after many washings. Some new fibers have the ability to inhibit the growth of bacteria, fungus, and mildew.

copper

Copper was probably the first metal used by humans. With its discovery, humankind moved from the Stone Age to the Bronze Age. Copper is durable and can be easily drawn or hammered into new shapes without breaking or tearing. Electrolytic or pure copper is used for electrical conductors and switches. Pure copper becomes brittle when heated. Common copper alloys include brass, bronze, and nickel silver.

More considerations

Cost: Will the cost of the material fit the budget for the product? Durability: How long should this product last? Ease of maintenance: Does this material require more maintenance than is reasonable for this product? Ease of disposal: How will the material be dealt with when the product is no longer useful?

Molecular

Covalent bonds usually form the molecular structure of solids. The bonds join a number of mers, a basic unit, to form complex, chain-like structures called polymers. We learned earlier that polymers can be natural, such as wood, or synthetic, such as plastic. All of these materials are made up of millions of polymeric chains.

Density

Density is the measure of a material's mass. The more density a material has, the heavier it will be. Density is measured in pounds per cubic foot, or kilograms per cubic meter. Sometimes the density of a material is compared to the density of water. This measure of comparison results in an index number that allows materials to be compared to each other. This measure is called specific gravity.

Where does it go?

Did you know that the plastic garbage bag you put out this morning will last for about 200 years? Plastic is a very durable material. This has caused a major disposal problem. There are three actions we can take to help solve this dilemma.

Feedback

Does the edible alloy meet the customer's requirements? The final product is measured against the goal of a crisp, sweet, chocolate chip edible alloy. There are bits of chocolate. Is the amount adequate? Is the texture crisp or hard? If the edible alloy isn't just right, this feedback will enable the system to adjust until it produces an edible alloy that meets the customer's requirements.

stone age

During the period called the Stone Age, materials processing was limited. People used their hands to dig clay or harvest vegetation from the earth. Later, they used stone knives and axes, and other stone tools to shape materials and grind grain. They used tools to separate materials like wood and stone. In addition, people used animal tendons to assemble animal hides into clothing and shelters.

The shell

Each electron has its own path around the nucleus, but several electrons can orbit at the same distance. These electrons are moving in what is called a band or shell. Each shell can have a maximum number of electrons. The grouping of electrons in the outermost shell determines: The chemical properties of the material The way the atoms bond together to form a solid The atom's size

bonding techniques

Either cohesive or adhesive bonding is used to bond materials. In cohesive bonding, the atoms of the materials being bonded must be as close together as the atoms within the material. Since simply placing the materials together doesn't create the needed atomic closeness, heat or pressure must be used to achieve it.

Like repels

Electrons are subatomic particles with a negative electrical charge that orbit around the nucleus. Because like charges repel each other and unlike charges attract each other, the negatively charged electrons are attracted to the positively charged protons in the nucleus. The force holds the electrons in their orbit. Although the electrons add very little weight to the atom, their orbits determine its size and volume.

Engineering materials

Engineering materials, or solids, can be divided into three basic categories: Ceramic Polymeric Metallic

Benefits

Every technological product changes life in one way or another. It may change they way we do tasks, our health, where we live, or other aspects of our lives. We have greatly benefited from technology. We can communicate with people far away by phone. We have a varied diet, which results in better health. Many diseases have been eliminated by medical technology. Almost all aspects of our modern life are dependent upon technology.

Ceramic

Golfers are using ceramic golf cleats instead of the metal ones that wear out over time. The ceramic golf cleats are easier and less costly to manufacture than metal cleats, but unfortunately they won't lower your golf score.

Materials section:A system

How can materials selection be a system? The inputs to materials selection are the requirements of the product. The processes are the types of actions taken to manipulate the materials so they will fit the requirements. The output is the material in its final form. This final form is tested against the "goals," or desired characteristics, of the material in the final product. The testing results provide the feedback for the system.

Seeking ability

If an atom loses or gains electrons through some action, it becomes a positively or negatively charged ion. Because nature likes balance, the ion tries to stabilize its structure. There are three ways that an atom can become stable. It can: Release extra electrons to become a positive ion Receive extra electrons to become a negative ion Share electrons with another atom In the search for structural stability, atoms bond to form solid materials. The type of bonding has a direct impact on the properties of a material.

Microgravity

In a microgravity environment, the effects of gravity are greatly reduced. This allows researchers to study a material's structure, properties, and processing requirements without the interference of gravity. In the Microgravity Research Division of NASA, researchers study materials in microgravity environments on Earth and in flight. Experiments are also performed in laboratories aboard the space shuttles. The space shuttle achieves microgravity by being in a continuous free fall around the Earth.

Linen

In ancient Egypt, the earliest textile was linen, a material woven from the flax plant. Linen was used for clothing and household articles and in religious practices. The Egyptians used linen strips to wrap their dead after they were mummified.

Covalent bonding

In covalent bonding, elements share electrons to produce a stable structure. Carbon, the material that is the basis of all organic compounds, participates in covalent bonding. Carbon atoms often form chain-like molecules with covalent bonds. These molecules are called monomers. A number of monomers can join to form a polymer or plastic.

Forming

In forming, pressure is used to give materials a size and shape. Material is placed in a die or fed through a set of rolls. These machines force the material to take a new shape. The size and shape change, but not the weight. Most metals, plastics and ceramics can be formed. Tools used in this process include hammers, presses, and rolling machines.

Recycling

In the developed world, millions of tons of nonrenewable, or exhaustible, resources are used each year. This consumption puts a strain on our planet's natural resources. Recycling is the process of reusing some of these nonrenewable resources. We are finding new ways to reuse metals, plastics, glass, and paper.

Separating

In the separating process, the desired form is obtained by removing excess material. For instance, in making furniture, lumber is cut into the needed shape. This process separates the unwanted part of the lumber from the part that is needed for the furniture. The part that is cut away is called scrap. Materials are separated by shearing or machining. Shearing operations cut the excess material away with tools like saws. Machining removes the excess material by chipping or shaving. Almost all materials can be separated. The material's size, shape, and weight are changed during the process of separating.

The atom

In the study of microstructures, the atom is the basic unit. At one time, atoms were thought to be the smallest particle that could exist. Yet scientists have now proven that there are even smaller units, called subatomic particles.

Iron

Iron is a ferrous metal that has been used in manufacturing for many years. It is found in nature only in meteorites. In the first processing step for iron ore, pig iron is produced in blast furnaces. Pig iron can be used as the basic ingredient in producing steel. Pig iron is also combined with about 3 percent carbon to produce cast iron. Cast iron is used to manufacture products such as heavy machinery parts and engine blocks for automobiles.

The body:A system

Let's look at your body as a system. The inputs are food, oxygen, water, and rest. The processes are functions such as breathing, digesting, and sleeping. The output is a living human. The goal is to be healthy. So if your body has a problem, such as taking in too little food, it gives you feedback telling you it's hungry. This feedback lets you know that you must make an adjustment in the system to reach the goal.

A concrete example

Let's use concrete as an example. Sand, gravel, and Portland cement each have their own characteristics. However, when you mix these three elements, it creates a new material, called concrete, that has unique properties of its own. To understand how concrete works, you must examine its macrostructure. It's as strong as the sand and gravel, and as stable as the portland cement.

Primary processing

Look at any product around you. You can trace it back to natural products. The wood in your pencil was once a tree, the metal band around the eraser was ore, the "lead" is actually graphite, a naturally occuring mineral, and the eraser was petroleum. The raw materials--the tree, mineral, ore, and petroleum--were processed before they became the products used to make the pencil. This first step is called primary processing. The steps in primary processing are obtaining raw materials, refining them, and making them into standard materials.

Dendrites

Many of the metal items we use daily, such as soda cans and aluminum foil, are formed from a molten substance that solidifies, or becomes a solid. If you examine a fresh sample of a metallic alloy with a strong magnifying glass, you'll see that the surface is made up of many tiny crystalline grains. Under a microscope, these tiny grains look like a forest of pine trees crowding and growing into each other. The tree-like structures are called dendrites.

Why condition?

Materials are conditioned to: Make them easier to form or separate Develop specific mechanical properties Reduce internal stress created by casting, forming, and separating.

Materials come in two categories

Materials are separated into two categories: organic and inorganic. Organic materials are or once were living things. Coal, silk, wood, and wool are examples of organic materials. Nonliving ores and earth elements such as copper, gold, and rock are inorganic materials. Both inorganic and organic materials are found in one of three states: gas, liquid, or solid. The term "engineering materials" is used to describe solid materials. Gases and liquids are called "nonengineering materials."

Making the match

Materials engineers and designers study the product descriptions, prototypes, and detailed drawings. In order to match these product requirements to characteristics of materials, they consider many factors, including: Properties: What properties of these materials will fit the uses of the product? Are there any properties that may cause a problem? Uses: How will the material behave under the product's conditions of use?

Crystalline

Metals and most ceramics have a crystalline structure. The atoms are arranged in a regular pattern of three-dimensional structures called crystals. Although there are 14 possible crystalline structures, most metals have one of three structures. Crystals unite to form grains of materials that then interconnect to form a solid structure. The areas between the grains are called the grain boundaries. Metals tear or break along these boundaries. The strength of the metal is determined by how easily these breaks or tears occur.

Metals and Metal alloys

Microgravity research with metals and metal alloys is aimed at producing more stable and less costly metals to be used in airplanes, power tools, and building materials. Scientists study how the internal structure of the metal affects its properties. A metal's strength and resistance to corrosion are determined by its internal arrangement of atoms. This arrangement develops as the molten metal solidifies. By understanding this process, scientists can learn how to manipulate the properties of a metal.

Microstructurw

Microstructure describes the structure of the molecules and crystals that make up a material. This structure determines how a material reacts to stress, temperature, chemicals, and other factors. The various ways a material reacts are described as its properties.A material's microstructure is so small that you must use a microscope to see it. When you study the microstructure of a material, you learn about the atomic particles and how they're held together.Materials Scientists look at materials at their most basic level--as atoms and molecules. Atoms are the basic components of all materials. Molecules are combinations of two or more atoms.

mid steel or low carbon steel

Mild or low carbon steels have a carbon content up to .30 percent. They can't be hardened by heat treatment. Mild steels bend easily and aren't as strong as medium and high carbon steels. A process called cold working increases the material's hardness and makes it less bendable.

Processes

Mixing and baking are the processes used to turn our edible flour alloy into a chocolate chip cookie. The amount of time the edible alloy is mixed and baked, as well as the baking temperature all affect the way the cookies turn out. If the alloy is overmixed, the chocolate chips can break up. If it's baked for eight minutes, the edible alloy is soft and chewy. Yet, if it's baked for ten minutes, you may have a hard edible alloy.

Moisture content

Moisture content is a measure of how much water is contained within the structure of a material. It is defined as the weight of water as a percentage of the weight of the material without moisture. This measure is particularly important with wood products. The moisture content helps to determine how a wood product will adjust to the environment, as well as how much it will expand and contract.

Ores

Most metals are derived from ores that can be extracted commercially from rocks or earth. Some rocks contain metals that are too expensive to refine. The term "ores" is used only for the metals that can be commercially extracted. Sometimes, metal will appear in pure veins, as did the gold that was mined from the famous Mother Lode of California. But usually metal must be extracted from its ore. Ore is shipped to a plant, where it's refined into useful materials for manufacturing. The impurities that are separated and removed are called slag.

nonwoven fabrics

Nonwoven fabrics are produced by bonding or interlocking the fibers. This is accomplished by mechanical, chemical, thermal, or solvent methods, or by a combination of these methods. Chemical methods use resins to bond the fibers. Thermal methods blend a heat-setting fiber with a base fiber. Then heated rollers cause the fibers to bind together. The main mechanical method of producing nonwoven fabrics uses a needle-punch machine with small hooked needles to interlace and interlock the fibers.

final decision

Often designers must make trade-offs when selecting materials. For example, steel might be the best material for a ballpoint pen, but most consumers won't pay what would have to be charged for a pen produced with steel. So a less expensive material like plastic is selected.After all materials are selected, the bill of materials is completed. All of the product information is sent to the production department, where the manufacturing process begins.

Space shuttle tile

One of the most expensive and famous types of ceramic is what was used to protect the space shuttle from burning up during re-entry into Earth's atmosphere. This high-performance, fiber-based ceramic tile is slightly over one inch thick. It can protect the aluminum skin of the space shuttle from a re-entry heat of 2,300 degrees Fahrenheit.

more products

Products could now be manufactured more quickly and cheaply. Everyone had more goods, and the standard of living improved. During this period, new products were invented and new materials were discovered. A practical way to process aluminum was developed in the first half of the 1800s. During the second half of the 1800s, new processes made steel affordable for large projects. The first synthetic fiber, rayon, was developed during this period.

Design sketches

Rough sketches called thumbnail sketches are a first design step. After the best ideas are selected, detailed drawings called renderings are created. Designers and draftspersons use computer-aided design (CAD) systems to create these drawings. CAD programs greatly speed up the design process. New ideas can be tested and revised quickly. Designers can even test certain aspects of the product design on the computer.

Surface texture

Run your hand over the top of your desk. How did it feel? Your desk should have a smooth surface texture. Some products, like sandpaper, have a rough texture. Materials engineers and designers match the surface texture to the product requirements.

Reduced-gravity aircraft

Scientists also achieve microgravity using special aircraft. Such an airplane does a fast climb until its nose is at about a 45-degree angle to the horizon. The pilot briefly cuts the engine, the plane slows, and the nose falls rapidly. This creates a microgravity environment for 20 to 25 seconds. On a typical flight, a plane may repeat this action 40 times.

Semi-conductor materials

Semiconductor materials play an important role in modern life. These materials are used in computers, lasers, communications systems, and medical equipment. The properties of semiconductor materials are related to their crystalline perfection. Research in microgravity provides scientists the opportunity to experiment with controlling the purity of crystalline structures. This knowledge will allow the development of semiconductors that are smaller and better conductors of electricity.

Fabric shelters

Shelters made from quality, polymer-coated fabrics are designed for use as emergency response shelters. These shelters can be inflated and set up by as few as two people for temporary use in an emergency. They're also durable enough to be joined together for use as a long-term building. These shelters are already in use by emergency response units in New Zealand and Singapore.

silk

Silk is obtained from the silkworm. According to Chinese legend, silk weaving started around 2600 B.C. For around 3,000 years, the Chinese carefully guarded the secrets of how to gather and weave silk. Eventually, silk was produced in other countries. In the mid-20th century, however, Japan and China were the only important silk producers.

Nanotechnology is technology with the goal of manufacturing objects and structures with atomic precision--that is, designing materials atom by atom. Living cells do this, but evolution, not design, guides the changes. Nanotechnology will allow the structure of matter to be controlled completely and inexpensively.

Some clothing manufacturers are currently using embedded nanoparticles to create stain-repellent khakis. This seemingly simple innovation will impact not only khaki-wearers, but dry cleaners, who will find their business declining.

materials from trees

Standing trees that will be logged are called timber. Boards cut from timber are called lumber. Thin layers of wood, called veneer, are sliced from logs then joined together to make plywood. Wood chips are used to make particleboard and flakeboard. Trees are processed into lignin and cellulose fibers. These fibers are then used to produce paper and hardboard.

Steel

Steel is either plain carbon or high alloy steel. Carbon steel has up to 1 percent carbon, but no more than 1.65 percent magnesium, .60 percent silicon, and .60 percent copper. The American Iron and Steel Institute (AISI) identifies carbon steel by a numbering system. In carbon steel, the first number in the four-digit system is one. The last two digits identify the carbon content in points. A point is 1/100 of a percent. So AISI 1028 means that the carbon steel is 28 x .01, or .28 percent carbon.

High carbon steels

Steels above .55 percent carbon are called high carbon steels. These are coarse steels that are hardened by heat treatment--a type of thermal conditioning. Generally, the higher the carbon content of the steel, the harder it becomes under heat treatment. High carbon steel is hard and extremely durable. It's used in products like drills, springs, piano wires and saw blades.

surface coatings

Surface coatings are either organic or inorganic. Organic coatings come from petroleum and resin or from natural gums produced by trees. These include paint, varnish, enamel, and lacquer. Inorganic coatings are layers of ceramic or metallic materials deposited on the base material. Typical ceramic coatings are porcelain enamel and glaze. Metallic coatings include chromium, zinc, and tin. With powder coating, as shown in the video, fine particles of epoxy are used that, during a heating process, are actually melted onto the product.

Ceramic igniter

The igniter that lights the burner on gas stoves is made from recrystallized silicon carbide. This type of igniter eliminates the need for a standing pilot light. It reaches a minimum temperature of 1,825 degrees Fahrenheit in 40 seconds.

Strength

The most common measures of strength are: Tensile strength: the ability to resist being pulled apart Compression strength: the ability to resist crushing Fatigue strength: the ability to resist failure after repeated twisting around an axis Impact strength: the ability to absorb energy during impact; also called toughness

aluminum

The most commonly used nonferrous metal is aluminum. It's the most widely distributed of all metals and is found in all common clays. Aluminum is nonmagnetic, forms easily, and oxidizes readily at high temperatures. Aluminum conducts heat well and ordinarily does not react chemically with food ingredients. Because of this, it's used to make cookware and cooking utensils. Aluminum's light weight makes it valuable as a building material. It is sometimes substituted for iron in engine blocks and aircraft.

The other side

The same factors that can make all these incredible possibilities a reality can also create a nightmare situation. Futurists predict that the period of transition from our current world to that of nanotechnology could be a time of immense danger, instability, and uncertainty.

Ceramics

The stronger, nonabrasive ceramics that scientists are developing through microgravity research will improve fuel efficiency in combustible engines. Microgravity research has also developed bioceramic materials used for artificial bones and teeth. Other research has resulted in improved glass fibers that are used in telecommunications devices.

Most manufactured products have some type of finish. Paint is applied to cars, glaze to dishes, and varnish to most furniture. Finishing includes all processes that convert or coat the surface of a material. These finishes may be used to protect the product or to beautify it. Finishing requires three steps: Selecting a finishing material Preparing the base material to accept the finish Applying the finish

The two types of finishes are conversion finishes and surface coating finishes.

amorphous structures

The word amorphous means "without form." However, materials with an amorphous structure do have size and shape. It is the internal structure of these materials that is amorphous; the atoms are not arranged in any regular repeating pattern. Liquids, molten metal, and glass all have an amorphous structure.

exhaustible resource

There are limited amounts of some of the substances found on our planet. Some of these substances are nonliving resources that can't reproduce. Others, such as petroleum, take millions of years to form. Once we've used all the available resources, these materials will no longer exist. Examples of these types of resources, called exhaustible resources, are minerals, petroleum, and natural gas.

Wood composites

There are several common wood composites. Plywood is made by gluing thin layers of wood at right angles to the layer above. This method keeps plywood strong and resistant to warping. Other common wood composites are particleboard, waferboard, hardboard, and fiberboard.

Thermoplastics

Thermoplastics are materials that have polymer chains with few cross-links. Because of this structure, chains can move past one another. This allows thermoplastics to be heated and reshaped repeatedly. These plastics lose their shape when heated. If you've ever left a videotape in your car on a very hot day, you experienced what happens when these plastics are heated.

Cam follower

This cam follower, made of silicon nitride, is used in both internal-combustion piston engines and gas turbines. The low-wear properties of this ceramic allow these engines to operate at very high temperatures and pressures.

Refractory brick

This is probably the least expensive type of ceramic, but one of the most important. These bricks are used to line or coat the inside of high-temperature furnaces. Since they can withstand temperatures up to 3,250 degrees Fahrenheit, the steel walls of the furnace will not melt.

silicon nitride

This isn't your average skateboard bearing, but rather a special ceramic used in ball bearings for satellites. These ball bearings never need lubrication, which would be difficult in space. These silicon nitride bearings are noncorrosive and nonconductive.

Armor

This life-saving ceramic, called Armor Tile, is used in police and military armor vests to stop armor-piercing, .30-caliber bullets. This type of ceramic is 85 percent aluminum oxide.

more nonferrous metals

Tin is a soft, easily shaped material that melts at low temperatures. It's used as an alloying element with steel. Tin is also used as a coating for steel--as in "tin" cans. Lead is a soft, heavy, easily shaped metal. It's used in chemical applications and storage batteries. If you've ever had an x-ray, you probably noticed that the technician wore a heavy apron for protection. This apron was made of lead. Lead is also combined with tin to form the solder used in assembling electrical parts.

More tests

Torsion describes a material's ability to resist being twisted around an axis. To test torsional strength, put one end of the material in the vise and grasp the opposite end with pliers. Try to twist the material. If it resists twisting, the material has good torsional strength.

Product designers and materials engineers must match a material to the requirements of a product. Selecting the best material for the job is a critical task. A poor choice can result in an inferior product. For example, during World War II, cargo ships began to break up in rough seas because the wrong type of welding material had been used to build the ships. In this case, a poor choice of materials was costly--not only in terms of lost cargo vital to the war effort, but also in terms of human life.

Understanding the properties of materials allows designers to select the best material for the job.

recyclable plastic

We can encourage manufacturers to use more recyclable plastics by only buying products that are packaged with recyclable materials. Currently, Americans recycle a tiny percentage of the plastics they use. By making sure that we recycle and encouraging others to do so, we can increase this percentage.

Converting yarn into fabric

Weaving, done on a loom, uses two sets of yarns, the warp and the woof, to make fabric. Warp yarns run the length of the loom, while woof yarns run across it. Warp yarns form a series of parallel threads through the loom. The loom shuttle carries woof yarns across the loom, interlacing them at right angles with the warp yarns.

conversion fishing

With a conversion finish, the surface of a material is converted into a protective layer. This is done by passing an electric current through a solution that conducts electricity, which causes the metal to develop a hard oxide layer. Chemicals are also used to create a conversion finish.

Adhesive bonding

With adhesive bonding, a film of a tacky substance is applied to the surfaces to be bonded. The materials are then joined or clamped to create the bond. Organic adhesives join materials by extending polymer chains between the materials. The number and strength of these chains controls the strength of the adhesive. Bonding agents are often added to improve the strength of an adhesive.

hardwood and softwood

Wood is classified into two groups, based on the type of tree from which it was cut. Hardwood is cut from broad-leafed, deciduous trees such as oak or cherry. Evergreen conifers with needle-like leaves produce softwoods.

wool

Wool, sheared from sheep, was used by many ancient civilizations. The earliest textiles used in the southern European region were woven from wool. Today, 40 different types of sheep produce about 200 kinds of wool.

Simple tests

You can perform several simple tests on a material to test its mechanical properties. You'll need a vise to hold the material you're testing. To test for hardness, stroke the surface of the material with a file twice. A very hard material will not scratch. Ductility describes a material's ability to bend. To test it, place one end of a material sample in the vise. Grasp the other end with a pair of pliers. Bend the material back and forth several times. Check to see if the material cracked or broke. A material with high ductility will be easy to bend and will not crack.

Synthetic polymers are plastics. The first plastic, celluloid, was produced over 100 years ago. It was made to replace ivory for billiard balls. A later product, Bakelite, was used to produce many products, such as radio cases and hairbrushes. Plastics are composed of base organic chains called monomers. There are 24 families of monomers, including acrylic, silicon, epoxy, and propylene. These base materials are used to produce many familiar products

You probably own an acrylic sweater and carry snacks in a polyethylene sandwich bag. Plexiglas is another acrylic product.