Everyday we use different kinds of metallic items, whether they are our kitchen utensils or garage tools – they have become common in our daily lives.
Iron is one such metal that has been and still is used in many machines or tools or utensils due to its useful properties. Below discussed are the properties of iron in forms of different items:
Is iron a good conductor of heat?
Heat is conducted through a material by means of vibration of the atoms. Good conductors such as iron have free electrons which can move around freely to transfer heat throughout the iron structure. So when iron is being heated, its free electrons vibrate quickly and conduct heat quicker.
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Iron is a naturally found metal most common in the Earth’s crust. It is also one of the most commonly used metals due to its availability, strength and low cost.
It is used to make rigid structures such as bridges, girders and even small but useful tools such as nails, screws and pipes.
Iron is not very reactive, which makes it ideal and safe to remain exposed to the air. Besides, they can be processed into much stronger materials such as steel.
Cast iron:
Another form of iron is cast iron, which is hard and brittle but also useful in places such as manhole covers or car engines.
Iron is also used not just for its strength and rigidity, it is known for its good conductivity of heat as well – which made it suitable to use as utensils.
However, this thermal conductivity can be unwanted as well in places where iron is used to build important structures.
You would be generally led to believe that since iron is a good conductor of heat – so is cast iron.
However, the reason cast iron is used to make skillets, grill pans, and Dutch ovens is because they heat up very slowly. They have poor thermal conductivity, thus cast iron utensils heat up and lose heat slowly.
Iron rods:
Iron rods are mostly made of iron but do have some composite elements in it. However, due to their high composition of iron, they are good conductors of heat.
Although they are good conductors of heat due to being mostly composed of iron, they remain inside reinforced concrete so they are not exposed to heat.
Iron nails:
Iron nails are made of steel, which is an alloy of iron and a bit of carbon.
Due to this distinct composition, iron nails are a poor conductor of heat. Iron nails may be used in structures or locations which are exposed to high heat – and their poor conductivity prevents them from causing the structure they are attached to from catching fire.
Black iron:
Black iron pipe is commonly used in water lines, but also has seen its popularity in gas lines as well.
Black iron pipes are steel pipes with a black coating which is built to handle high pressure and temperature. Therefore, they are poor conductors of heat as well.
Why is iron a good conductor of heat?
Iron is one of the commonly known metals that are used in many machineries and objects due to its good thermal conductive properties. Below are the reasons why iron is a good conductor of heat compared to other objects:
They have higher conductivity due to free electrons:
Most non-metallic objects are poor conductors of heat because their atoms are stuck in a lattice and cannot move. The best they can do is vibrate within their designated spaces. When they are heated, they vibrate until they have dissipated the heat out.
In the case of iron, they have free electrons – which means they are not stuck in a fixed position unlike non-metallic objects. Which is why these electrons can carry the heat throughout the metal when heated.
Their atoms can vibrate to a greater extent:
Exposure to heat causes atoms to gain energy which causes them to vibrate about in their fixed position – which causes them to dissipate the gained energy overtime and thus, objects get hot.
Atoms in non-metallic objects vibrate as well when they are exposed to heat but their vibrations are not as high compared to metals – which is why they take so long to heat up.
But in the case of metals, they vibrate more vigorously which is why they heat up faster.
The electrons can carry thermal energy:
Just vibration of atoms is not enough to make an element a good conductor of heat. The free electrons in iron have the capability to absorb heat from the vibrating atoms and travel throughout the structure to dissipate the heat to the rest of the space.
Is iron a better conductor of heat than copper, aluminum and brass?
Although iron is a good conductor of heat, it is not the best conductor and there are several alternatives to iron in the market as a better conductor such as copper, aluminum and brass.
Copper among them all is the best conductor of heat because of how its internal structure is – which provides very little resistance to its free electrons when they are transferring thermal energy.
Another better conductor of heat is brass, but there are two types of brass – yellow and red.
However, both variants of brass are good conductors of heat because they have a lower resistivity of heat compared to iron. But they are still inferior to copper and aluminum in terms of thermal conductivity.
Aluminum is yet another conductor of heat which has a higher conductivity rating than iron.
However, iron can retain and transfer heat more effectively than iron whereas aluminum conducts heat faster. But Aluminum costs less, which makes up for its poor thermal conductivity.
Why does copper conduct heat better than iron?
According to the value of thermal conductivity, copper has the highest rating among all whereas iron falls way below copper in that regard. In the list below, you will get to know the reasons why copper conduct heat better than iron:
Amount of energy carried by the electrons:
The rate at which an object conducts heat heavily depends on the amount of energy the metal’s free electrons can carry.
The greater the amount of energy a metal can carry, the faster the metal will heat up and the higher thermal conductance rating it will have.
All metals, copper and iron included, have free electrons that can move around the structure freely and are also responsible for carrying the heat around from the vibrating atoms.
But the electrons in copper in comparison to iron have a larger capacity to carry heat – which is why each electron in copper can carry the same amount of heat in a shorter time.
The density of atoms in the copper lattice:
Atoms vibrate about in their own lattice when they gain energy from being heated. They vibrate about their own position to dissipate the energy to its neighbors.
Atoms in copper are tightly held together which transfers the heat between the atoms more efficiently. Iron atoms are not as tightly packed as the ones in copper, which is why some of its heat gets dissipated outside.
How does iron conduct heat?
Iron is being used in all sectors starting from machinery to household items due to its strength and thermal conductivity. Below are reasons explained as to why iron conducts heat so well:
They have free electrons:
In order to transfer heat energy from one place to another, a carrier medium is needed. In non-metallic objects, there are no carriers in them to transmit heat energy across the structure – which is why they are poor conductors of heat.
But iron has free electrons which can be used to carry heat energy from the receiving end to other parts of the iron structure.
They have mobile electrons:
Just having free electrons is not enough to conduct heat because if the free electrons face enough resistance within the lattice that stops their movement – they cannot carry the heat energy.
Iron has free electrons which are mobile and can overcome the resistance within the lattice.
Their mobility allows them to carry the heat energy from the receiving end and move throughout the structure – constantly dissipating the heat to neighboring atoms.
Atoms vibrate to conduct heat:
As the high energy electrons move past the atoms throughout the structure and provide them with thermal energy, they all vibrate due to this excess energy.
This vibration of atoms heat up all the parts of the metallic structure and thus allow heat to be evenly conducted throughout the iron structure.
Final Thoughts
Heat is carried through a medium by the vibration of its atoms. Iron, for example, has free electrons that may travel around freely to transport heat throughout the iron structure. As a result, when the iron is heated, its free electrons vibrate rapidly, making it a good conductor of heat.