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For thousands of years, bronze and copper has been a useful metal even before the age of aluminum and steel. Till today both metals still have a wide application in the modern-day manufacturing industry. Both metals are referred to as red metals in the industry and as a result of their ancient existence, they have provided a starting place for other metals in form of alloys. However, bronze is an alloy of copper and it can be somehow tricky to differentiate from copper. In this regard, this article will explore copper and bronze to draw comparisons to differentiate them. This article features the physical, chemical, as well as mechanical properties of copper and bronze in a detailed fashion.
As said earlier, this article aims to draw comparisons between bronze and copper using varieties of properties. But before we proceed to differentiate bronze from copper, let’s take an insight into bronze and copper.
In a lay man’s voice, bronze is simply the result of adding tin to copper, although it contains more than just tin. Bronze was discovered in about 3500BC before the exact chemistry method was developed. Today, bronze is referred to as an alloy of copper that has been defined based on specifying alloying elements and working properties.
Bronze as an alloy of copper is made up of alloying elements other than copper and tin including manganese, lead, zinc, nickel, antimony, silicon, and more. This elemental composition of bronze is responsible for its improvement and as result, designers in the industry now have a vast variety of bronze grades to choose from. Consequently, a typical bronze is brittle and appears reddish-brown/gold with low friction when in contact with other metals.
Copper is known as a native metal and it is occasionally found as a free metal in nature. Artifacts of this native metal were first discovered in primitive areas such as Indians of the Pacific Northwest which are known from antiquity dating back to about 5000 BC. During this ancient time, copper was used for curating weapons, tools, and was also available for decorative applications.
Today, copper now has a wide variety of applications because it is soft, ductile, and malleable, with a very high electrical and thermal conductivity. Its application is found in building constructions, conductor of heat and electricity, and as a constituent for producing other metal alloys. Such alloy applications include bronze, brass, cupronickel, and many more. A freshly exposed piece of copper displays a reddish-brown coloration.
In this chapter, we focus on drawing comparisons using different individual properties of bronze and copper.
Bronze and copper can be differentiated by drawing a comparison using their elemental composition. In comparison, copper is a non-ferrous transition metal that exists in its pure state. Unlike bronze, it is a naturally occurring metal, and it’s directly suitable for processing. Besides its natural occurrence, it can also exist as an alloying element in other metals such as bronze.
On the other hand, bronze which is a copper alloy is made up of copper (Cu) and tin (sn) as its primary elemental composition. Besides its primary composition, it contains other elements depending on its alloy form, they include:
A way to differentiate between bronze and copper is to draw comparisons using their level of resistance to corrosion. Bronze – an alloy of copper is found to oxidize when exposed to air to form a protective layer called mottled patina. This reactivity is attributed to its copper content and as a result, the bronze surface is prevented from corrosion. This is particular for a saltwater environment, hence – the reason for its application in marine parts and boat fittings. However, whenever bronze has any contact with chlorine compounds, its copper content degrades gradually over time. This process is known as “bronze disease”.
On the other hand, copper can also undergo oxidation to form a mottled patina to prevent corrosion. Since both metals contain no iron, they are said to possess excellent corrosion resistance. Conclusively, bronze is naturally more resistant to corrosion compared to copper.
The electrical conductivity of a metal is referred to as the measure of the quantity of current generation created by a material’s target surface. Mostly in the manufacturing industries, copper is the standard by which electrical materials are rated. This means that the conductivity rating of these materials is then expressed as a relative measurement to copper. Copper is considered to be 100% conductive while other conductivity rating is expressed as IACS – International Annealed Copper Standard.
On the other hand, bronze is said to be 15% conductive as copper. Bronze is made up a copper majorly, but it has a low electrical conductivity which can be attributed to the presence of other alloying elements.
Thermal conductivity is another measure with which copper and bronze can be differentiated. It is the measure of how copper and bronze can be used in thermal applications. In the process of measuring their thermal conductivity, the amount of energy and rate at which the energy can be transferred is determined. In comparison, bronze is an alloy of copper while copper is in the form.
Alloys have a thermal conductivity that increases with temperature while pure metals have a thermal conductivity that stays the same with increasing temperature. Bronze has the highest thermal conductivity (229 – 1440 BTU-in/hr-ft²-°F) while copper is the least (223 BTU-in/hr-ft²-°F).
It is very important to consider the melting point of a material for a project. This is because, at melting, a material used as a component of a machine can fail. At this point, the materials could not serve its purpose as it has transited from its solid form to its liquid state.
Also, if the materials are considered for formability, the melting point of such materials is a very important consideration. This is because the lower the temperature the more formable the material will be. Copper has the highest melting point compared to bronze. Copper melts at 1084 oC while bronze melting point ranges between 315 – 1080 °C.
The hardness of a material is referred to as its resistance to local plastic deformation that is achieved from the indentation of a predetermined force onto a flat surface. The hardness of a material can be measured using the Brinell hardness scale which is one of the common tests of hardness available. On this scale, copper scores 35 which is lower in metric compare to bronze with a score that ranges from 40 to 420. This result depicts that bronze is a lot harder than copper. As a result, it is brittle which makes it more prone to fracture compared to copper.
If workability is a requirement for a project, copper is a perfect choice. However, if resistance to wear and strength becomes the requirement over workability then bronze is considered over copper.
Weight comparison is also a crucial factor in selecting either bronze or copper for a project. In a situation where lightweight is an important requirement for the success of a project, bronze seems to be a perfect choice. This is measured using water as the baseline specific gravity – given the value of 1. Based on metric bronze exhibit a density ranging from 7400 – 8900 kg/cu.m making bronze the lightest of the pairs. On the other hand, copper exhibit a density of 8930 kg/cu.m making it the heaviest.
The durability of a material is predicated by good renewability, good repairability, coupled with maintenance. Every durable material must be capable of adapting to technological, technical, and design evolutions. In light of this, bronze is a hard and sturdy metal material and it’s not easily flexed. It is highly corrosion-resistant because of its ability to withstand water. On the other hand, copper exhibits great flexibility compared to bronze. Therefore, bronze can be said to be a much stronger and more durable alternative to copper.
Machinability is a comparative score given to metallic materials to ascertain how the metallic materials react to machining stress. This machining stress may include stamping, turning, milling, and more. When the machinability o bronze and copper is compared, copper exhibited more machinability. This may be attributed to the hardness of bronze. Bronze is hard and study, not easily flexed compared to highly flexible copper.
Also, alloys of copper are pretty much ductile to machine. As the case may be, if machinability is a goal in selecting either bronze and copper for a project, it is of no doubt that copper is a perfect choice.
Formability is referred to as the ability of a material to exhibit plastic deformation without being damaged when formed. In this regard, copper is said to have exceptional formability which is evident in its ability to produce micron-sized wire with the minimum softening anneals. However, some certain bronze is formable including PB1 phosphor bronze which can be cold formed by using die forming techniques.
Bronze and copper are weldable in their respective domain and they can also be joined together by using MIG equipment and silicon bronze welding. Out of all grades of bronze that is weldable, unleaded bronze demonstrates fair weldability because they crack under a stressed condition. This may be avoided by using SMAW.
On the other hand, oxygen-free and deoxidized copper are more easily to weld. MIG and TIG are the preferred welding method while MMA and oxyacetylene welding can be used in the repair of tough pitch copper components.
The yield strength of a material is referred to as the stress at which a predetermined quantity of permanent deformation occurs on such material. In comparison, bronze exhibits a higher yield strength than copper. To support the claim, bronze has the highest yield strength at 69.0 – 800 MPa (10000 – 116000 psi) while copper possesses 33.3 MPa (4830 psi).
In the industry today, a lot of manufacturers consider the strength of the material as one of the crucial factors for selecting one material over the other. This case isn’t an exception to this – hence, one of the reasons for this comparison. When we compared the two, we discovered that in a situation where strength is required, bronze is a perfect choice. Bronze displays a tensile strength that ranges from 350 MPa to 635 MPa while copper display tensile strength of 210 MPa.
The shear strength of a metal is the property that describes that metal’s resistance against a shear load before the component fails in shear. The strength sliding failure or shear action as portrayed by shear strength normally occur parallel to the direction of the force acting on a plane. In comparison, bronze exhibits the highest shear strength ranging from 35000 psi to 47000 psi. on the other hand, copper exhibits the lowest shear strength (25000 psi).
It may be somehow tricky to ascertain the color of bronze and copper. Both metals are somehow reddish-brown but they can be differentiated. Bronze’s reddish-brown is characterized by a dull gold while a freshly exposed copper is characterized by pinkish-orange color.
Since bronze and copper may exist in different grades, their price may vary. However, while the price of bronze and copper may vary per grade, copper is typically the most expensive when the same piece of materials are compared. The reduced price of bronze may be attributed to the reduced content of copper in the copper alloy.
Bronze is a copper alloy that exists in vast varieties of forms. It is found in a vast array of applications. Bronze is used in applications such as musical instruments, electrical contact, and for both ships’ propellers and submerged bearings. Some specific bearings are made of bronze due to their excellent friction resistance, hardness, and wear-resistant properties. As a result, they are used for springs, bushings automobile transmission pilot bearings, bearings for small electric motors, and many more.
Bronze is applicable in making hammers, mallets, wrenches, as well as other durable tools because when struck against a hard surface, they generate no spark. Bronze is widely used for manufacturing bronze wool for woodworking applications. Another common application of bronze is that it is used for casting bronze sculptures. They are regarded as the highest form of sculpture art in Ancient Greek. Bronze exist in different alloys and their properties are described below:
This type of bronze grade is commonly used in the industry for its high strength and corrosion resistance. 863 Manganese Bronze is an ideal option for heavy-duty applications as a result of its durability, and longevity. It is majorly found in the application including construction and agricultural equipment. It is applicable in manufacturing the following:
This bronze alloy is highly known for its quality corrosion resistance and its application is found in seawater exposure. While 907 Tin Bronze is moderately machinable, it performs excellently in wear and fatigue applications. This grade of bronze is applicable in manufacturing
The 917 Tin Bronze is popularly known for its load-carrying capacity in a slow and irregular movement load-carrying capacity material. When used, it requires adequate lubrication and is highly corrosion-resistant. The 917 Tin Bronze can be found in the following applications:
Among the toughest non-ferrous alloys available in the industry is the 955 Aluminum Bronze. It offers a vast variety of benefits for its users such as high hardness and elongation, superior compressive and yield strength, corrosion-resistant to seawater, high thermal resistance, and many more. The 955 Aluminum Bronze is one of the most sought after weldable and machinable bronze. It offers applications in the following:
This type of bronze alloy is an extremely strong grade that features superior corrosion resistance amongst all grades. As a result, it is popularly known and used in the manufacturing industry today. The 954 Aluminum Bronze offers increased weldability, high yield and tensile strength, temperature strength, and many more. The 954 Aluminum Bronze is found in the following applications:
Copper is mostly used as a pure metal, but in a situation where greater hardness is a thing of priority, it is fashioned into bronze or brass. For over two centuries copper paint has been in use on boat hulls to control plant growths and shellfish. Besides, copper has been used although in small quantities for nutritional supplements and fungicides in agriculture. The following are the major application of copper as found in the manufacturing environment:
As said in chapter two, under the electrical conductivity section, copper is always used as the standard in measure of electrical conductivity of other conductive materials. It possesses 100% conductivity while other conductive materials are measured relative to copper.
As a result, copper remains the most preferred electrical conductor in this space. This can be found where copper is used for electrical wiring, although it is less preferred for overhead electrical power transmission. Its usage is majorly found in transmission, distribution, power generation, telecommunication, circuitry, and a large variety of electrical equipment.
Copper is used to replace aluminum in printed circuits and integrated circuit boards as a result of its superior conductivity. Copper is also used in heat sink and heat exchangers because it features the superior property of heat dissipation. Can be used in electromagnets, cathode ray tubes, vacuum tubes, magnetrons in microwave open, and many more.
Copper has always been sought after due to its efficiency in electrical motors. There has been an increased utilization of copper in manufacturing the coils used in electric motors. In all the consumption of electricity, the motor and motor-driven system takes up to 43% to 46%. This means that copper is highly used in this space.
Right from the discovery of copper, copper has been found to have applications in flashings, vaults, doors, roofs, rain gutters, downspouts, doors, roofs, domes, spires, and many more. This is because copper is a durable, corrosion-resistant, weatherproof architectural material.
These days, copper now has added benefit as it is used in interior and exterior wall cladding, building expansion joints, radio frequency shielding, and many more. In architectural designs, copper is used in indoor decorative products including handrails, fixtures, countertops, bathrooms, and many more.
Another impressive use of copper is for antimicrobial use. It can be converted into alloys that offer antimicrobial activities. An example of a range of organisms it can prevent is the Escherichia Coli. Parts made from this copper alloy are majorly used in the public health sector in manufacturing over-bed tables, health club equipment, toilet hard wars, sinks, shopping card handles, and more. This application can be found in countries such as the UK, Japan, Us, China, Korea, Australia, Brazil, and many more.
Copper has application in preventing the growth of many forms of life in which it is said to biostatic. Due to its biostatic nature, copper is used to lining the ship’s parts for protection against barnacles and mussels. Copper features impressive antimicrobial activity and as a result, it is often used for manufacturing netting materials to prevent biofouling.
Copper is used as a means of investment these days due to its increasing usage in the manufacturing space. Some investors now store copper in form of metal rounds and bars while others invest in its usage for the production of solar panels, turbine engines, and other renewable sources of energy.
|Shear Strength||35000 psi to 47000 psi||(25000 psi)|
|Tensile Yield Strength||69.0 - 800 MPa (10000 - 116000 psi)||33.3 MPa (4830 psi)|
|Ultimate Strength||55.2 - 1010 MPa (8000 - 147000 psi)||210 MPa|
|Thermal Conductivity||229 - 1440 BTU-in/hr-ft²-°F||223 BTU-in/hr-ft²-°F|
|Melting Point||315 - 1080 °C||1084°C (1220°F)|
|Hardness||40 – 420||35|
|Weight||7400 - 8900 kg/cu.m||8930 kg/cu.m|
Bronze and copper can be differentiated using their respective color. Although it may be tricky, it can be swiftly done.
The question of “which is better?” can be best answered based on requirements or priority. It can’t be answered generally. So, we can say that both metals work best in a mode of action. While one is better in a specific application, the other can be better in other application.
When it comes to cost, both materials copper is typically the most expensive among the duo. This is because copper is pure and it is expensive while bronze is not made up of 100% copper. Consequently, the reduced contents of copper contributed to the reduced price of bronze.
Mere comparing the same size of copper with bronze using water as the baseline specific gravity – given the value of 1, copper exhibit the heaviest weight. Bronze display a value ranging from 7400 to 8900 kg/cu.m in density while copper exhibit a density of 8930 kg/cu.m.
To determine the hardness of both copper and bronze, the Brinell hardness scale will be used.
This scale depicts that copper scores 35 which is lower in value compared with the score of bronze at values ranging from 40 to 420. This shows that bronze harder than copper.
Copper is an excellent choice for metal injection molding but it's neither hard nor strong in its pure form. However, alloys of copper such as bronze retain much of the conductivity while attaining strength and hardness. Therefore, bronze may be preferred over copper for metal injection molding. For example, aluminum bronze is commonly used for metal injection molding.
Both bronze and copper can be used in 3D printing. Bronze is an alloy of copper that may be preferred over copper because of its higher resistance to tarnish than pure copper itself. Besides, bronze has a harder surface that is not easily oxidized when exposed to air. Another reason is why bronze is better is that it is the most affordable choice.
Bronze is usually preferred for bushings and this is due to its low metal on metal friction compared to copper.
Generally, copper is more flexible compared to bronze. If the machinability of copper and bronze is to be considered for a project, then copper is said to be more machinable. On the other hand, bronze is hard and not easily flexed.
To weld both metals together, the MIG welder and gun can be used to braze bronze and copper together. To make this joining easier, use MIG equipment and silicon bronze welding wire and with quality process. However, the silicon wire heating may not be enough to melt the copper base material.
Getting to know how to differentiate between bronze and copper would help spare gigantic measures of capital. This is because using the wrong metal for a project may be disastrous. However, the best metal between copper and bronze still lies on the requirement of your project. Notwithstanding, if you are not sure of the perfect line of action, seek expert advice.
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