Sapphire glass is a material that has been applied in multiple fields due to its excellent physical properties. However, there are many practical limitations that need to be considered, including cost, processing difficulty, optical performance, and adaptability to specific environments.

The processing of sapphire glass is challenging, which limits its use in products with complex shapes. With a Mohs hardness of 9, sapphire is renowned for its exceptional wear resistance; however, this also presents certain processing challenges. The conventional cutting and polishing procedures necessitate the use of diamond tools, which exhibit low processing efficiency and result in significant tool wear. In the manufacturing of curved screens or irregular structures, brittleness can lead to a significant decrease in yield rate.

In terms of optical performance, sapphire glass is subject to certain limitations. While its light transmittance performs well in the visible light range, there is potential for absorption peaks to occur at certain specific wavelengths. For instance, in the infrared wavelength, there is a significant drop in light transmission performance, which limits its application in some special optical instruments. Additionally, the refractive index is relatively high (approximately 1.76), and in certain optical designs, supplementary coating treatment may be necessary to minimize reflection loss, thereby increasing the complexity and cost of the optical system.

Sapphire glass exhibits dual mechanical properties. Despite its high surface hardness and excellent scratch resistance, its toughness is relatively insufficient. When subjected to impact, it is more prone to breakage than chemically strengthened soda-lime glass. When equivalent to the same thickness, sapphire glass displays a reduced level of impact resistance of approximately 60% compared with tempered glass. This feature places it at a disadvantage in application scenarios that require shock resistance, such as the use of sports smartwatches in harsh environments.

In addition, thermal performance represents a key limiting factor with regard to application. While a relatively high thermal conductivity can be beneficial in certain situations, it may present issues in environments subject to rapid temperature fluctuations. Due to a significantly higher coefficient of thermal expansion when compared to that of most metallic materials, stress concentration is susceptible to occurrence within the sapphire glass under conditions of temperature cycling, resulting in interface failure.

With respect to touch applications, the surface characteristics of sapphire glass also have certain limitations. Its surface energy is relatively low, which makes it easier for fingerprints and oil stains to adhere and difficult to wipe clean, affecting the user experience. Conversely, standard glass that has undergone a special treatment frequently exhibits superior stain resistance properties. Additionally, the attenuation of capacitive touch signals is significant, necessitating the incorporation of a more robust touch driver circuit within the device. This, in turn, increases power consumption and complicates the design.

While sapphire glass boasts numerous advantages, its application is constrained by several factors, including processing, optical and mechanical performance, thermal conductance, touch experience, size limitations, and design constraints. These restrictions mean that it is only effective in specific fields and difficult to achieve widespread application.