If you own a good quality watch probably it has a sapphire glass, and if that’s the case, you probably have in your palms one of the toughest substances in the world right now. Likewise, some versions of Apple watches and almost all cellphones use sapphire lens on their cameras.
Sapphire, in its natural form, is a precious stone typically blue in color that can be used in jewelry. Nevertheless, sapphire can be created synthetically and several optical products such as windows, sapphire ball lens, domes, etc., is built. It is this form that is endowed with valuable properties in many industries.
Why is Sapphire So Valuable?
You might question what makes sapphire so special. We will go more in depth about its characteristics, but here are five reason sapphire is so valuable.
- It is really very hard to scratch it. So it’s well suited for camera lenses and watches.
- It is almost completely transparent for a variety of wavelengths (infrared to ultraviolet)
- It can stand a big range of pressure and temperatures without deformation.
- Very resistive to acids
- It can be synthetically manufactured
Optical and Mechanical Properties
One of sapphire’s most well-known properties is its hardness. There are different ways to measure the hardness of a material. Two very common ones are the Mohs scale and the compressive/tensile stress. Mohs scale measures the resistance of a material against scratching. It is a qualitative scale with diamonds occupying its highest place, followed by silicon carbide, and, along with some other materials.Sapphireis in the 3rd place. Mohs scale just measures how easy it is for one material to scratch another.
An area where sapphire excels is its compressive strength.The pressure it can support before breaking is around 2 GPa for sapphire. To give you a rough estimate, 2 GPa is the equivalent of having 40 elephants stack on top of one another with the bottom one balanced on a single leg. For comparison, steel has a compressive strength of 250 MPa (almost 8 times less than sapphire), and Gorilla Glass has a compressive strength of 900 MPa (less than half of sapphire).
Also of interest is the fact that sapphire has excellent chemical properties being almost inert to all chemicals, which makes it suitable where corrosive materials are present. It has very low thermal conductivity and extremely low thermal expansion percentage. It does not deform or increase in volume under high pressure or high temperature conditions.
These properties of power and scratch resistance are utilized for customer applications including business and medical laser treatment, underwater camera, and marine environment spectrometers.
Due to the fact of its mechanical properties, sapphire is extremely hard to work with. Creating large pieces of it is technically challenging and shaping it to specific geometries can be challenging. Exactly the same properties that make it so attractive also allow it to be expensive.
One of the reasons we don’t see more consumer electronics with sapphire is because of the character of the marketplace itself. Mobile phones and laptops have a lifespan of less than eighteen months before a new set of models are away in the marketplace. Getting a high-value material like sapphire will make it extremely expensive for end users. Higher end wrist watches, on the other hands, are meant to last decades, so using sapphire does justice to its costs.
So, you see, sapphire is an extremely hard, chemically inert, and have several mechanical properties that makes it perfect for use in several optical applications. Products such as sapphire ball lens, windows, domes, can be manufactured using synthetic sapphire. However, the process of manufacturing and giving it a specific shape is quite intricate and the price of the finished products using sapphire is always higher than where standard glass is used. Hence, we find sapphire being used more in high-end optical devices for medical and laboratory uses and less in consumer electronics.