What are metals?
Metals are substances that form naturally below the surface of the Earth. Metals are inorganic, which means they are made of substances that were never alive. Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are, in general, denser than the other elemental substances.
What metals are non-ferrous?
Non-ferrous metals are alloys or metals that do not contain any appreciable amounts of iron. All pure metals are non-ferrous elements, except for iron (Fe).
Non-ferrous metals tend to be more expensive than ferrous metals but are used for their desirable properties, including light weight (aluminium), high conductivity (copper), non magnetic properties or resistance to corrosion (zinc).
The difference between ferrous and non-ferrous metals is that ferrous metals contain iron. Ferrous metals, such as cast irons or carbon steel, have a high carbon content, which generally makes them vulnerable to rust when exposed to moisture. However, this is not the case for wrought iron, which resists rust due to its purity, and stainless steel, which is protected from corrosion by the presence of chromium.
There are a large number of non-ferrous materials, covering every metal and alloy that does not contain iron. Non-ferrous metals include aluminium, copper, lead, nickel, tin, titanium and zinc, as well as copper alloys like brass and bronze. Other rare or precious non-ferrous metals include gold, silver and platinum, cobalt, mercury, tungsten, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium.What are some applications of non-ferrous metals?
Non-ferrous metals are used for a wide range of commercial, industrial and residential applications. This may require careful material selection according to their mechanical properties, including how easily the metal can be shaped and whether these properties will be altered in the process.
Many of the properties of ferrous metals can be found in non-ferrous materials, for example, aluminium or titanium alloys can replace steel in some instances, and the magnetic properties of iron can be emulated by cobalt, nickel or rare earth elements that have been alloyed.
However, because non-ferrous metals are often more expensive they tend to be used for their unique attributes rather than simply as a replacement for steel. These attributes include lighter weights, conductivity, corrosion resistance and non-magnetic properties. Non-ferrous metals also tend to be softer and more malleable than ferrous metals, meaning they can also provide aesthetic applications, as with gold and silver.Non-Ferrous Metals and Casting
Metals, both ferrous or non-ferrous, can be cast into the finished part or cast into an intermediate form like an ingot before being extruded, forged, rolled, wrought or worked into the desired shape. The reaction to non-ferrous metals to these processes is more severe than with ferrous materials, meaning that the properties of cast or wrought forms of the same metal or alloy may differ.
It is important to choose the right metal to balance performance with aesthetics as this may influence production methods. While ferrous metals tend to be chosen for castings, non-ferrous metals can also be chosen for properties such as corrosion resistance, lack of magnetism or weight rather than tensile strength. Materials like bronze or brass may also be chosen for appearance or tradition.Common Non-Ferrous Metals and Alloys
Because they include any metal that doesn’t include iron, there are lots of different non-ferrous metals and alloys. Here are some of the properties and common uses of some of the more common non-ferrous metals:
1. Copper
Having been used by humans for thousands of years, copper is still widely used by industry. The addition of copper alloys, brass (copper and zinc) and bronze (copper and tin) have widened the uses for this non-ferrous metal further (see below for detail on these alloys).
The properties of copper and its alloys include high thermal conductivity, high electrical conductivity, good corrosion resistance, and high ductility.
These properties have allowed copper and its alloys to be used for heat exchangers and heating vessels, as an electrical conductor in wiring or motors, as a roofing material, for plumbing fittings, as well as for saucepans and statues.
Copper also oxidises to a green colour.
2. Aluminium
Aluminium is an important metal that is used in a wide range of applications due to its low weight and ease of machining. Despite being a relatively expensive material, aluminium is also the base metal for many alloys.
Being corrosion resistant and a good conductor of heat and electricity (albeit less so than copper), as well as having good ductility and malleability, aluminium can require annealing as it becomes hard following cold working.
The light weight of aluminium makes it perfect for aerospace and automotive applications as well as for marine use in yachts. Aluminium is also found in bicycle frames, saucepans and drink cans.
3. Lead
Lead has been used over the centuries for a range of applications, including for bullets, in fuels and even in paint. However, it was found to be unhealthy when released into the atmosphere, while other applications also caused harm to users.
Lead is the heaviest common metal and is resistant to corrosion. It also doesn’t react with many chemicals and is soft and malleable.
Although many of its former uses are no longer allowed, lead is still widely used for batteries, power cables, and acid tanks.
4. Zinc
Zinc has been used for centuries as an alloying element, particularly to alloy steel for a range of purposes as well as alloying copper to create brass.
Galvanising materials with alloying elements offers them a greater resistance to rust, affording it uses for chain-link fencing, guardrails, suspension bridges, lampposts, metal roofs, heat exchangers, and car bodies. Zinc is also used as a sacrificial anode in cathodic protection (CP) and as an anode material for batteries. Zinc oxide is also used as a white pigment in paints and to disperse heat during rubber manufacture.
5. Silver
Silver has been used as a precious metal for centuries. With the highest electrical conductivity, thermal conductivity and reflectivity of any metal, silver is also soft and malleable when heated and is highly resistant to corrosion.
Used for jewellery and currency, silver can also be found being used in solar panels, for water filtration, in electrical contacts and conductors as well as for stained glass and even in specialised confectionary.
6. Gold
Another precious metal that has been used for jewellery and coinage, gold is the most malleable of metals as well as being ductile and resistant to corrosion and many other chemical reactions.
Its electrical conductivity has seen gold used in computer devices as well as for infrared shielding, for the production of coloured glass, for gold leaf and also for tooth restoration.
7. Magnesium
Magnesium is a really cool metal. It’s about 2/3rds the weight of aluminum, and it has comparable strength. It’s becoming more and more common because of this.
One of the most popular applications of magnesium is in the automotive industry. Magnesium is considered a step up from aluminum when it comes to high-strength weight reduction, and it’s not astronomically more expensive.
What metals can Aero-Ti produce?
Aero-Ti is different from conventional metal material companies. At Aero-Ti, we just make rare metal material including titanium, zirconium, tantalum, niobium, hafnium and special steel.
1.Titanium
As a metal, titanium is recognized for its high strength-to-weight ratio. It is a strong metal with low density that is quite ductile (especially in an oxygen-free environment), lustrous, and metallic-white in color. The relatively high melting point (more than 1,650 °C or 3,000 °F) makes it useful as a refractory metal. It is paramagnetic and has fairly low electrical and thermal conductivity compared to other metals. Titanium is superconducting when cooled below its critical temperature of 0.49 K.
Titanium is the fourth most abundant metal making up about 0.62% of the earth's crust. Rarely found in its pure form, titanium typically exists in minerals such as anatase, brookite, ilmenite, leucoxene, perovskite, rutile, and sphene. While titanium is relatively abundant, it continues to be expensive because it is difficult to isolate. The leading producers of titanium concentrates include Australia, Canada, China, India, Norway, South Africa, and Ukraine. In the United States, the primary titanium producing states are Florida, Idaho, New Jersey, New York, and Virginia.
Thousands of titanium alloys have been developed and these can be grouped into four main categories. Their properties depend on their basic chemical structure and the way they are manipulated during manufacture. Some elements used for making alloys include aluminum, molybdenum, cobalt, zirconium, tin, and vanadium. Alpha phase alloys have the lowest strength but are formable and weldable. Alpha plus beta alloys have high strength. Near alpha alloys have medium strength but have good creep resistance. Beta phase alloys have the highest strength of any titanium alloys but they also lack ductility.
The applications of titanium and its alloys are numerous. The aerospace industry is the largest user of titanium products. It is useful for this industry because of its high strength to weight ratio and high temperature properties. It is typically used for airplane parts and fasteners. These same properties make titanium useful for the production of gas turbine engines. It is used for parts such as the compressor blades, casings, engine cowlings, and heat shields.
Since titanium has good corrosion resistance, it is an important material for the metal finishing industry. Here it is used for making heat exchanger coils, jigs, and linings. Titanium's resistance to chlorine and acid makes it an important material in chemical processing. It is used for the various pumps, valves, and heat exchangers on the chemical production line. The oil refining industry employs titanium materials for condenser tubes because of corrosion resistance. This property also makes it useful for equipment used in the desalinization process.
Titanium is used in the production of human implants because it has good compatibility with the human body. One of the most notable recent uses of titanium is in artificial hearts first implanted in a human in 2001. Other uses of titanium are in hip replacements, pacemakers, defibrillators, and elbow and hip joints.
2.Zirconium
Zirconium is a lustrous, grey-white, strong transition metal that resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium is widely used as a cladding for nuclear reactor fuels. The desired properties of these alloys are a low neutron-capture cross-section and resistance to corrosion under normal service conditions.
Most zircon is used directly in high-temperature applications. This material is refractory, hard, and resistant to chemical attack. Because of these properties, zircon finds many applications, few of which are highly publicized. Its main use is as an opacifier, conferring a white, opaque appearance to ceramic materials. Zirconium and its alloys are widely used as a cladding for nuclear reactor fuels. Zirconium alloyed with niobium or tin has excellent corrosion properties. The high corrosion resistance of zirconium alloys results from the natural formation of a dense stable oxide on the surface of the metal. This film is self healing, it continues to grow slowly at temperatures up to approximately 550 °C (1020 °F), and it remains tightly adherent. The desired property of these alloys is also a low neutron-capture cross-section. The disadvantages of zirconium are low strength properties and low heat resistance, which can be eliminated, for example, by alloying with niobium.
3.Tantalum
Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as minor components in alloys.
The chemical inertness of tantalum makes it a valuable substance for laboratory equipment, and as a substitute for platinum. Its main use today is in tantalum capacitors in electronic equipment such as mobile phones, DVD players, video game systems and computers. Tantalum, always together with the chemically similar niobium, occurs in the mineral groups tantalite, columbite and coltan (the latter is a mix of columbite and tantalite, though not recognised as a separate mineral species). Tantalum is considered a technology-critical element by the European Commission.
As a metal powder, the primary application of tantalum is in the manufacture of electronic parts, especially capacitors and some high-power resistors. Tantalum electrolytic capacitors exploit the propensity of tantalum to form a surface layer of protective oxide, using tantalum powder, pressed into a pellet shape, as one "plate" of the condenser, the dielectric oxide, and the other "plate" as an electrolytic solution or conductive solid. Since the dielectric layer can be very thin (thinner than the equivalent layer in an aluminium electrolytic capacitor, for instance), a small volume of high capacitance can be achieved.
Tantalum is also used to manufacture a variety of alloys with a high melting point, strength, and ductility. It is also used in the manufacture of carbide tools for metalworking equipment and the manufacture of superalloys for components of jet engines, chemical process equipment, nuclear reactors, missile parts, heat exchangers, tanks, and vessels. Tantalum can be drawn into fine wires or filaments that are used for evaporating metals such as aluminium because of its ductility. Tantalum is commonly used in making surgical instruments and implants because it prevents attack by body fluids and is non-irritating.
4.Niobium
Niobium is a soft, grey, ductile transition metal, often found in the minerals pyrochlore (the main commercial source for niobium) and columbite. As the lightest of the refractory metals (a group of metallic elements that exhibit extremely high melt points and heat resistance), niobium is a highly sought-after material with applications in aerospace, electronics, nuclear power and defense. In this article, we explore the properties that set niobium apart from the other refractory metals, as well as its current applications and potential for use in future technologies.
Niobium consumption is dominated by its use as additive to high strength low alloy steel and stainless steel for oil and gas pipelines, car and truck bodies, architectural requirements, tool steels, ships hulls, railroad tracks. However, there are a number of other applications for niobium metal and its compounds. Although niobium has many applications the majority is used in the production of high-grade structural steel. The second largest application for niobium is in nickel-based superalloys. Niobium-tin alloys are used as superconducting magnets.
5.Hafnium
Hafnium is a lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Hafnium’s large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.
Hafnium has good neutron-absorbing properties, and hence it is used in control rods in nuclear reactors, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors. While hafnium nitride is the most refractory of all the metal nitrides, hafnium carbide is the most refractory of all the binary materials. With a melting point of about 3900 °C it is one of the most refractory binary compounds known. Hafnium has been successfully alloyed with several metals including iron, titanium and niobium.
6.Special Steel
Special steel is made by adding various elements to iron. We make it to achieve various properties, such as heat resistance, hardness, and corrosion resistance. Can be used in extremely harsh environment. Mostly used in special industries. Special steel mainly includes the following four categories: heat resistant steel series, super austenitic steel, double phase steel series, nickel base alloy series.
Structures of Metals
Metals account for about two thirds of all the elements and about 24% of the mass of the planet. They are all around us in such forms as steel structures, copper wires, aluminum foil, and gold jewelry. Metals are widely used because of their properties: strength, ductility, high melting point, thermal and electrical conductivity, and toughness.
Metals account for about two thirds of all the elements and about 24% of the mass of the planet. They are all around us in such forms as steel structures, copper wires, aluminum foil, and gold jewelry. Metals are widely used because of their properties: strength, ductility, high melting point, thermal and electrical conductivity, and toughness.
1.Bonding
Such bonds could be formed between metal atoms that have low electronegativities and do not attract their valence electrons strongly. This would allow the outermost electrons to be shared by all the surrounding atoms, resulting in positive ions (cations) surrounded by a sea of electrons (sometimes referred to as an electron cloud).
Figure 1: Metallic Bonding.
Because these valence electrons are shared by all the atoms, they are not considered to be associated with any one atom. This is very different from ionic or covalent bonds, where electrons are held by one or two atoms. The metallic bond is therefore strong and uniform. Since electrons are attracted to many atoms, they have considerable mobility that allows for the good heat and electrical conductivity seen in metals.
Above their melting point, metals are liquids, and their atoms are randomly arranged and relatively free to move. However, when cooled below their melting point, metals rearrange to form ordered, crystalline structures.
Figure 2: Arrangement of atoms in a liquid and a solid.
2.Crystals
To form the strongest metallic bonds, metals are packed together as closely as possible. Several packing arrangements are possible. Instead of atoms, imagine marbles that need to be packed in a box. The marbles would be placed on the bottom of the box in neat orderly rows and then a second layer begun. The second layer of marbles cannot be placed directly on top of the other marbles and so the rows of marbles in this layer move into the spaces between marbles in the first layer. The first layer of marbles can be designated as A and the second layer as B giving the two layers a designation of AB.
Layer "A"
Layer "B"
AB packingFigure 3: AB packing of spheres. Notice that layer B spheres fit in the holes in the A layer.
Packing marbles in the third layer requires a decision. Again rows of atoms will nest in the hollows between atoms in the second layer but two possibilities exist. If the rows of marbles are packed so they are directly over the first layer (A) then the arrangement could be described as ABA. Such a packing arrangement with alternating layers would be designated as ABABAB. This ABAB arrangement is called hexagonal close packing (HCP).
If the rows of atoms are packed in this third layer so that they do not lie over atoms in either the A or B layer, then the third layer is called C. This packing sequence would be designated ABCABC, and is also known as face-centered cubic (FCC). Both arrangements give the closest possible packing of spheres leaving only about a fourth of the available space empty.
The smallest repeating array of atoms in a crystal is called a unit cell. A third common packing arrangement in metals, the body-centered cubic (BCC) unit cell has atoms at each of the eight corners of a cube plus one atom in the center of the cube. Because each of the corner atoms is the corner of another cube, the corner atoms in each unit cell will be shared among eight unit cells. The BCC unit cell consists of a net total of two atoms, the one in the center and eight eighths from the corners.
In the FCC arrangement, again there are eight atoms at corners of the unit cell and one atom centered in each of the faces. The atom in the face is shared with the adjacent cell. FCC unit cells consist of four atoms, eight eighths at the corners and six halves in the faces. Table 1 shows the stable room temperature crystal structures for several elemental metals.
Table 1: Crystal Structure for some Metals (at room temperature)
table1
Unit cell structures determine some of the properties of metals. For example, FCC structures are more likely to be ductile than BCC, (body centered cubic) or HCP (hexagonal close packed). Figure 4 shows the FCC and BCC unit cells. (See Crystal Structure Activity)
Body Centered Cubic
Face Centered CubicFigure 4: Unit cells for BCC and FCC.
As atoms of melted metal begin to pack together to form a crystal lattice at the freezing point, groups of these atoms form tiny crystals. These tiny crystals increase in size by the progressive addition of atoms. The resulting solid is not one crystal but actually many smaller crystals, called grains. These grains grow until they impinge upon adjacent growing crystals. The interface formed between them is called a grain boundary. Grains are sometimes large enough to be visible under an ordinary light microscope or even to the unaided eye. The spangles that are seen on newly galvanized metals are grains. (See A Particle Model of Metals Activity) Figure 5 shows a typical view of a metal surface with many grains, or crystals.
Figure 5: Grains and Grain Boundaries for a Metal.
3.Crystal Defects:
Metallic crystals are not perfect. Sometimes there are empty spaces called vacancies, where an atom is missing. Another common defect in metals are dislocations, which are lines of defective bonding. Figure 6 shows one type of dislocation.
Figure 6: Cross Section of an Edge Dislocation, which extends into the page. Note how the plane in the center ends within the crystal.
These and other imperfections, as well as the existence of grains and grain boundaries, determine many of the mechanical properties of metals. When a stress is applied to a metal, dislocations are generated and move, allowing the metal to deform.