When we talk about the chemical element carbon, the first thing that may come to our mind is carbon dioxide gas. Interestingly, this tetravalent nonmetallic element can exist in several forms and form a variety of compounds. While carbon can attach to itself in one manner to form the hardest material called diamond, it can also arrange itself to form one of the softest known substances called graphite. These two structurally different arrangements of the same element are known as allotropes. Graphite, anciently known as plumbago, is a crystalline allotrope of carbon, with its atoms arranged in hexagonal structures. It is made up of extended planes of sp2-hybridized carbon atoms securely bonded to three other carbon atoms. (Graphite’s extremely high melting and boiling points are due to the strong bonding between carbon atoms within each plane.) However, the distance between these atom planes is substantially more than the distance between atoms within the planes. Since the bonds between planes are weak, deforming the solid by moving one plane relative to another is easy in graphite. Contrary to popular belief, carbon-carbon bonds are stronger in graphite than diamond. Nonetheless, the lattice structure of the carbon atoms within diamonds contains three-dimensional lattice bonds, whereas graphite contains two-dimensional lattice bonds that make the structure more vulnerable to deformation. Although graphite is flexible, it is non-elastic and has high electrical and thermal conductivity. It is also chemically inert and highly refractory. Since graphite displays low adsorption of X-rays and neutrons, it is very valuable in nuclear applications. The most prominent attribute of graphite is its stability under standard temperature and pressure conditions, which makes it widely applicable for several uses in daily life. Let’s discuss a few uses of graphite in everyday life.
1. Pencil Lead
Pencil lead is perhaps the most common application of graphite that many of us are aware of. In fact, the word graphite is from the Greek language which translates as “to write.” Graphite leaves the mark on paper by physical abrasion, which can be easily erased with rubber, but they are otherwise resistant to moisture, most chemicals, ultraviolet radiation, and natural aging. There is a common misconception that pencil contains the element lead; however, lead was only used to write or paint in the stone age and there is no evidence that lead was ever used to write on paper. After the commercialization of graphite as pencil lead, it soon emerged as a preferable material of choice for the manufacturing of cannonballs. England enjoyed a monopoly on the production of pencils until a method of reconstituting the graphite powder was found in 1662 in Italy.
The modern world of technology is mostly about making gadgets portable and easy to access, which has significantly increased the demand for portable power sources that we call batteries. A key component that has paved the way for this success story in the past almost 30 years is graphite, which has served as a lithium-ion host structure for the negative electrode. The excellent conductivity of graphite due to the presence of free electrons, along with magnificent porosity, durability, lightweight, and low cost, makes it one of the most preferable materials for the manufacturing of anodes for ion batteries. Graphene, single layer graphite arranged in a two-dimensional honeycomb lattice, shows impressive enhancement in these properties, which makes it employable in the manufacturing of fast-charging batteries that are used as a power source in smartphones. A graphene battery can be lightweight, robust, and ideal for energy storage with large capacity, as well as shorter loading times. It will increase the battery life that is adversely correlated with the amount of energy that is sprayed on the surface and applied to the electrodes to obtain conductivity and graphene provides conductivity without needing the amounts of carbon used in traditional batteries. Besides Li-ion anodes, high-grade graphite is also used in fuel cells, solar cells, semiconductors, LEDs, and nuclear reactors.
Touch Screens may not be considered one of the most wonderful inventions of the 20th century, it surely is one of those inventions without which the age of information technology (on which the 21st century is dependent) and more importantly, the smartphone revolution would not have happened. Touchscreens have been around in several forms for the past few decades although the kind of touchscreens that are at the cutting edge and the ones we use today are the capacitive types of touchscreens. Graphene has an awesome combination of two properties: transparency like glass and conductivity like metals. These two properties are one of the most basic requirements for the efficiency of touchscreens. Capacitive touch screens work by measuring capacitance at a number of locations on the screen, then interpolating between them to get a precise position. The simplest form of the capacitor is two parallel conductive plates on opposite sides of an insulator, with the capacitance being proportional to the area of intersection of the two plates and the dielectric constant of the insulator, and inversely proportional to the distance between the plates. In the case of a touch screen, one plate is a transparent conductor on the backside of the glass, and the other is the user’s fingertip. A pencil does not work well for this, even if made of metal, because its tip has a very small area.
4. Art Supplies
Most of us started drawing when we were young; however, it takes a great amount of practice to master the skill. Most painters would be lost without their graphite pencils. A graphite pencil is crucial for quickly recording ideas and building up compositions, whether you’re a painter, sculptor, textile artist, or crafty hobbyist. If you enjoy urban sketching or Plein Air painting, they’re ideal for use in sketchbooks and are easy to transport. Moreover, powdered graphite is often used to modulate the texture of several types of paints.
Most of us like to enjoy music every now and then. Graphene is used to make the 40mm acoustic drivers that deliver sound to the ear. The dynamic drivers, also known as moving coil drivers, employ an electrically charged voice coil to move a cone and produce sound waves. These drivers are made up of more than 95% graphene and preserve the majority of the material’s mechanical qualities while being easier to shape and less expensive to manufacture. It is a lightweight, rigid, and low-density material that is perfect for loudspeaker membranes. The heavier a speaker’s cone, the harder is to drive. Since graphene has such a high strength-to-weight ratio, graphene drivers can reduce the amount of power needed to move the coil back and forth, resulting in increased efficiency and better sound. As a result, earphones with graphene drivers are lighter and more compact.
6. Car Brakes
When it comes to the braking system of your vehicle, the most important component is friction. The brake system must be reliable and display unchanging action throughout its use, as it guards the health and life of many people. Most vehicles manufactured today use disc brakes. The main element of this type of design is the disc, spinning alongside the road wheel, and the brake pad, connected with the hub via a caliper. As the pad is pressed against the disc, friction occurs and transforms kinetic energy into heat. Unfortunately, due to friction in the contact areas, excessive temperatures are generated that may lead to the destruction of the pad’s structure and lead to the separation of its components. With its lubricating properties and excellent thermal conductivity, graphite modulates the braking effect of friction by improving the removal of energy from the contact area and preventing friction elements from overheating.
7. Dry Lubricants
Lubrication is one of the most prominent features of graphite. Dry lubricants, sometimes known as solid lubricants, are compounds that, despite being solid, may reduce friction between two surfaces sliding against each other without the use of a liquid oil medium. Due to the presence of weak Van-der-Waal forces, the layers of graphene sheets present in graphite can slide over each other with a minimum coefficient of friction. It offers lubrication at higher operating temperatures than liquid and oil-based lubricants. Although graphite is widely used in heavy machinery for the purpose of lubrication, it can also be found in several items of daily use such as locks, piano gears, ball bearings, brass instrument valves, etc. It is also used in air compressors, the food industry, and railway track joints.
Due to its excellent electrical and heat conductivity, graphite has become a quite popular material in the world of electronics. In the last few decades, a variety of electrochemical sensors have been developed and successfully applied to various fields such as gas sensors for the detection of harmful gases, metal sensors for water quality analysis, etc. Pencil Graphite electrodes (PGE) are often used as voltammetric sensors in analytical chemistry for various electrochemical measurements. Its abundance at ultra-low-cost with various interesting properties, such as mechanical flexibility, chemical inertness, low background current, wide potential window, analyte adsorption, and ease of miniaturization, has made it a choice of material for the manufacturing of several electrochemical sensors.