Our Location
A Comprehensive Guide to Bronze Metal
Bronze is a versatile and popular metal used in many projects, including automobile and marine parts, musical instruments, and tools. Its properties, such as corrosion resistance and low friction levels, make it suitable for various industries. Let’s explore the properties, characteristics, and uses of bronze that can benefit your business.
The Origin of Bronze
The Bronze Age is the period when bronze was widely used as the hardest metal, and this time in history occurred around the 4th millennium BC, coinciding with the rise of the city of Sumer in the Near East. The Bronze Age in China and India also happened around the same time. Although a few items were crafted from meteoritic iron during the Bronze Age, iron smelting was rare. The Bronze Age was followed by the Iron Age, which began around 1300 BC. Even during the Iron Age, bronze continued to be widely used.
Source: Bronze Age
Chemical Composition of Bronze
Bronze is a harmonious combination of copper and tin at its core. This alloy comprises 88% copper and 12% tin, offering exceptional strength and malleability. What’s fascinating about bronze is its versatility; the blending of copper and tin creates a unique synergy.
Aluminum, manganese, and phosphorus are commonly added to this metal blend to refine its characteristics. This has led to the development of various bronze alloys, each tailored to specific applications. The composition of bronze is a delicate balance that transforms it into a material with infinite potential, suitable for everything from intricate sculptures to sturdy industrial components.
Types of Bronze
- Aluminum Bronze: Aluminum bronze contains 6% to 12% of iron, nickel, and aluminum. It is a durable metal that is resistant to wear and corrosion. This type of bronze is ideal for use in pumps, valves, and other equipment that will contact corrosive fluids.
- Cupronickel: Cupronickel is a bronze alloy made of nickel and copper, with nickel content ranging from 2% to 30%. The alloy shows excellent thermal stability and high resistance to corrosion, especially in environments with steam or moist air. In seawater, it has superior properties compared to other forms of bronze. Cupronickel is used in the marine industry for ship hulls, pumps, valves, electronics, and marine gear.
- Silicon Bronze: Both red silicon bronze and red silicon brass are types of silicon bronze. Red bronze has a lower zinc content than red brass, which contains 20% zinc and 6% silicon. Silicon bronze has lower lead content and may also contain manganese, tin, or iron. It is known for its exceptional strength and high resistance to corrosion, making it a popular choice for manufacturing pumps and valve stems.
- Nickel silver: Nickel silver is not actually made of silver, despite its name. It is named for its silvery appearance. This alloy contains zinc, nickel, and copper. Nickel silver is capable of resisting significant force and has good corrosion resistance. It is used in various products, including tableware, optics， decorations, and musical instruments.
- Tin Bronze: Phosphor bronze, also known as tin bronze, contains tin concentrations of 0.5-1.0% and phosphorus concentrations of 0.01-0.035%. This alloy is hard and sturdy, with fine grain, a low coefficient of friction, and high fatigue resistance. Phosphor bronze is used for various applications, including bellows, washers, electrical equipment, and springs.
- Manganese Bronze: Manganese bronze is an alloy composed of copper, zinc, aluminum, iron, and up to 3% manganese. This alloy can absorb impact without breaking, instead deforming. Due to its high durability and resistance to corrosion in salt water, it is commonly utilized for manufacturing boat propellers. Additionally, manganese bronze is found to be applicable to producing gears, nuts, and bolts.
- Bismuth Bronze: Bismuth bronze contains between 1 and 6 percent bismuth. It is more malleable, corrosion-resistant, and an excellent thermal conductor. Because it polishes so well, it is sometimes used in mirrors and light reflectors. It can most often be found in bearings in an industrial setting, although traditionally, it has been used in the kitchen. It has replaced leaded bronze in several contexts.
The Properties of Bronze
Physical Properties of Bronze
| Physical Property | Description |
| Density (g/cc) | 5.60 – 9.30 |
| Color | Reddish-brown metallic color |
| Melting point (°C) | 315 – 1180 |
| Boiling Point (°C) | 1400 |
| Thermal Conductivity (W/m-K ) | 1.01 – 208 |
Chemical Properties of Bronze
| Chemical Property | Description |
| Corrosion resistance | Good |
| Electrical and thermal conductivity | Good |
| Oxidation products | Copper oxide and copper carbonate (green patina) |
| Malleability | Good |
| Good | High |
| Magnetic | No |
Characteristics of Bronze
- Excellent surface finish
- High ductility
- Excellent dimensional precision
- High electrical and thermal conductivity
- Corrosion and metal fatigue resistance
- Expansion when hardening
- Low friction
- High melting point
- Hard elemental property
- Bronze has non-sparking and non-magnetic properties compared to other common metals, such as steel.
The Manufacturing Process of Bronze
Here are some of the processes involved in manufacturing bronze:
Machinability
When working with bearing bronze, using the proper techniques is crucial to get the best results. It’s recommended to use coolant/lubricant while machining and to tip machine bits or tools for a better finish on your project. Although bearing bronze is durable, it requires more care in certain operations. For example, slower speeds are advised during reaming to prevent possible “grabbing.”
Corrosion Resistance
Bronze is a corrosion-resistant metal perfect for withstanding harsh environments such as saltwater and chloride. Its unique patina finish gives it a distinct character that can be easily preserved or removed depending on your preference – whether you want to maintain its original shine or embrace an interesting aged feel.
Annealing
When working with bronze, it is essential to achieve annealing or stress relieving through gentle metal heating at 260°C per inch of wall thickness for one hour. It is crucial to avoid quick cooling, as this could cause the material to crumble or fracture. Instead, allow it to air-cool slowly. Exercise additional caution when handling silicon bronze due to its higher lead content, and ensure that proper extraction equipment and personal protective equipment (PPE) are available.
Casting
Bronze casting has been used for centuries to create various beautiful items, including musical instruments, sculptures, plaques, and medals. Artisans use techniques like lost wax, ceramic shell, or sand casting to carefully pour molten bronze into molds and bring their visions to life with creative finesse.
Formability and Ductility
Bronze can be transformed through a specific cold-forming process, leading to increased durability and strength. Bearing bronze has low friction properties, making it ideal for various applications. Additionally, bell bronze emits resounding tones, and several bronze alloys possess admirable resistance to corrosion by seawater.
Bronze is a remarkable metal because of its ductility, which allows it to be drawn into tiny wires without breaking. Generators worldwide use this wonderful property of phosphor bronze in their design, which is a remarkable testament to its power.
Applications of Bronze
- Small Bronze Parts
Because bronze is corrosion-resistant, has high strength, and possesses a unique color, it can be used to manufacture various small parts such as coins, marine hardware, furniture trim, automobile parts, hardware mounts, metal letters, and springs.
Bronze is highly resistant to corrosion in both salt and fresh water, making it an ideal choice for applications such as engine parts, propellers, pumps, and bells.
- Bronze Casting
Bronze casting is a process in which a molten alloy is poured into a desired mold and then allowed to solidify. The resulting product is called a casting, which is a hardened bronze component. Bronze is easy to machine and pour, making it ideal for creating components such as pumps, bearings, valve stems, and bushings for various engines. Due to its low-friction characteristics and thermal resistance, bronze is a dependable material for applications where parts must slide against each other.
- Architecture
Architects often use bronze to construct structures when they want to maintain the natural or original appearance of the alloy. For instance, bronze is commonly used to create various components for bridges. In order to prevent bronze from oxidizing, the material’s raw finish can be preserved by applying oil, polishing, or by using a special lacquer.
- Instruments
Due to its durability and unique sound properties, bronze is preferred for making bells, cymbals, saxophones, and other musical instruments. It is also used for the windings of nylon and steel strings in guitars and pianos, creating a warmer sound compared to other metals.
- Bronze Wool
As the alternative to steel wool, bronze wool does not shed or leave stains on wood. It can be used to polish and sand metal surfaces and wood and is ideal for industrial, construction, and marine applications.
- Sculptures
Artists use bronze to create sculptures because it is a preferred metal for sculpting. Bronze expands before the setting, allowing intricate details to come to life in a sculpture. Additionally, as bronze cools, it constricts, making the mold easy to remove.
- Tools
Some tools, such as axes, hammers, wrenches, and mallets, can spark when they come into contact with flammable materials, creating safety hazards in your work area. However, bronze is a non-sparking and non-magnetic alloy, so it is increasingly used to make different tools. This helps to ensure a safer environment when working with other flammable or explosive objects.
Advantages & Disadvantages
Advantages
- It is much harder compared to pure copper or iron.
- The coefficient of friction is lower than that of copper.
- It is easier to cast because it’s more fusible than copper.
- It offers superior corrosion resistance, heat and electrical conductivity, and fatigue resistance compared to most steels.
- It is versatile, durable, and suitable for a wide range of applications.
Disadvantages
- It’s commonly more costly than steel, brass, and copper.
- Bronze is more prone to oxidation than copper.
- Because of its hardness, bronze can be more challenging to work with than pure copper.
- It has limited resistance to ferric compounds, cyanides, and ammonia. Chlorine and sulfur in a humid environment can bring bronze to deteriorate.
- Bronze Disease is a condition characterized by the sudden appearance of small, pale green rough spots. It occurs as a result of a reaction between oxygen and chloride in water, producing hydrochloric acid. This acid causes corrosion similar to rust in iron-based metals. If left untreated, this process leads to the formation of copper and tin chlorides, ultimately destroying the bronze.
Difference Between Bronze and Brass
The distinction between bronze and brass is based on their compositions. Both are alloys of copper and zinc. Historically, it has been challenging to differentiate between the two. “Bronze,” an Italian term meaning “bell metal or brass,” comes from an old Persian word for brass. The French word “bronze” is derived from the Italian word bronze, making “bronze” itself of French origin. Earlier artifacts with varied compositions are more accurately classified as “copper alloys.”
Summary
Bronze has played a significant role throughout human history and is a widely used metal. The diverse combinations of metals used to create bronze alloys have led to many variations available in the market. The enduring popularity and versatility of bronze make it a valuable material with a rich history and wide applications.
Choosing bronze offers numerous benefits, including exceptional durability and versatile applications. Whether used in sculptures, sand casting, rapid prototyping, or various industries, bronze is a reliable and cost-effective option.
Enze is the ideal provider of various bronze parts. Whether you need machined or fabricated for your projects, Enze is the right choice. With over years of experience, our technicians have expertise in machining and finishing. You can trust us to provide excellent one-stop services to meet your requirements. Get in touch with us today and entrust your next project to the hands of professionals!
