Free Fun Fact

Melting and Freezing; Fundamentals to Factories

(Free, Fun, Fact)

Have you ever paused to consider the remarkable journey of the solid materials that inhabit your daily life? The story of their origin is nothing short of astonishing. Behind the scenes, a myriad of invisible processes shape everything we encounter on Earth.


This is the tale of solids born from liquids, a narrative that echoes from the planet's formation to the cutting-edge technologies of today. From the humble rock to the sleek marvels of automotive engineering, the influence of melting and freezing processes spans the spectrum of existence, leaving an indelible mark on the natural and industrial worlds alike.


Are you intrigued to delve deeper into the fascinating realm of melting and freezing? Prepare to be captivated as we uncover the secrets hidden within these elemental transformations.

Do you know that approximately a hundred million tons of metal are being solidified annually in the world?

  1. In the emergence of nature

According to some theories (theory only!! as no one existed during Earth's formation), Earth was initially formed from molten liquid material. As it began to cool, freezing processes shaped the Earth's crust. The center of the Earth (the so-called inner core) is also a frozen liquid material due to high pressure at the center. Freezing processes are still occurring in the Earth's outer core as the liquids continue to cool every year. Most importantly, many rocks (igneous rocks) formed on Earth are frozen magma.

Not only in the formation of the Earth, but several natural processes like frost formation during winter, the dynamics of floes in oceans, and the dynamics of magmas in volcanoes also involve melting and freezing, which have a significant impact on variations in climate and ocean movement. In recent times, frost formation is reported to cause damage to crops.

2. Forging Human Civilization

Melting and freezing are indispensable entities in human advancement, and the names of ages are given by the alloys that were able to melt and freeze at that time; for example, during the Bronze Age (3000-1200 BC), bronze (a copper-based material) was the primary tool for humans. Only after the successful melting of iron did the next era, i.e., the Iron Age, begin. With the development of various methods and materials, humans have progressed into engineered materials. However, freezing processes remain integral to many commercial materials. Most of the metallic materials we use every day undergo melting and freezing processes before reaching us, as it is an inherent process in the manufacturing industry. Details are presented in the following section. 

3. In the manufacturing industry(Pin to plane production)

Within the crucible of the manufacturing industry, melting and freezing are the alchemical processes that transform raw materials into the products that enrich our lives. Through metal casting, metal joining, crystal growth, and additive manufacturing, these processes give rise to everything from everyday objects to cutting-edge technologies, each imbued with the legacy of their liquid origins. 

To serve human livelihoods, a plethora of materials need to be engineered and produced in large quantities. Melting and freezing (solidification) processes serve this purpose in developing many novel materials, some of which are discussed in the following subsections.

Metal Casting:

In this process, molten liquid is poured into a mold or container and solidified into intricate or simple shapes, as the liquid takes the form of the container. In many industries, the liquid is solidified into ingots, which are further converted into sheets, wires, billets, and other products. Today, casting forms the basis for developing many everyday products, from pins used to hold documents to airplanes transporting human beings to far-off places. Depending on the application, materials with specific properties are tuned by controlling solidification processes; for example, metallic materials can be brought down to a semiconducting regime. Thus, most commercial materials are born from the liquid.

Metal Joining:

Most metal joining processes, whether welding different materials or soldering crucial electric circuits, involve local heating (to melt) and subsequently cooling the material to solidify as a joint. The mechanical strength or electrical connectivity of the joints depends on the control over the melting and freezing process. Such processes are crucial even in the making of fashion gold ornaments (for several designs).

Crystal Growth (crystal is an ordered solid):

For some special material synthesis, liquids are cooled very slowly in a controlled manner to obtain atomic-level purity and specific properties. Such processes and materials are critical in the semiconductor industry. Similarly, non-crystalline materials (glasses) are produced by cooling melts at a very high rate, which has advantages in specific applications. When cooled slowly, certain materials are as strong as a wall, and when solidified rapidly, they could be as brittle as a dry flower.

Additive Manufacturing:

Also known as 3D printing, additive manufacturing is the current state of the industry's art. Solidification processes occur in some additive manufacturing technologies where control over the process produces the desired product.

Therefore, understanding the melting and freezing processes is imperative. In the following section, the art/science of freezing/solidification is presented.

4. Art, science in freezing

The unseen magic spell of solidification lies in the hidden structures inside the materials. The physical phenomenon of liquid transformation into solid is an interplay of many physical parameters that exhibit beautiful designs inside materials, which are not visible to the human eye. These hidden structures are revelations of elements arranging themselves in a particular fashion to contribute to various properties. Investigating such internal structure formation during freezing is exciting, as these structures can be modified by varying the solidification conditions in a controlled way, which is useful for designing many novel materials. 

5. Melting and freezing in art and chocolates

Till now, we have seen art in frozen solid. Now, let's explore melting and freezing in art. We love magic. Magicians perform tricks using such processes; for example, they design spoons with materials having low melting temperatures, which melt when stirred in hot tea, coffee, or water. They select materials that melt at lower temperatures, highlighting that solidification is not limited to the production of materials but is also used in art.

Ending on a sweet note, we all love chocolates. The science of chocolate making considers the melting and freezing temperatures of chocolate so that it can quickly melt at human body temperature inside the mouth. All the ingredients of the chocolate are melted down at temperatures around 40℃. These melted ingredients are poured into cubic trays and solidified at temperatures below room temperature. The outcome of such careful combination and solidification is truly relished!

Conclusions

As we journey through the realms of nature, industry, and art, we are reminded of the profound impact that the processes of solidification and melting have on our world. From the grandeur of geological formations to the intricacies of microchip design, these fundamental processes shape our lives in ways both seen and unseen. So the next time you encounter a solid material, take a moment to appreciate the magic of its journey from liquid to solid, and let its story inspire wonder and awe in your heart.