Fused silica and fused quartz are two types of high-purity silica glass. Fused silica is mainly used in high-precision lenses, optical windows and large space telescopes; fused quartz is mainly used in semiconductors and fiber optic communications.
Fused quartz and fused silica are two terms often used interchangeably. They are both made from pure silicon dioxide (also known as silica) and have similar physical and chemical properties. However, they differ in their manufacturing processes and specific characteristics. Understanding the differences between fused quartz and fused silica is important in selecting the right material for each application.
SIMILARITIES
1. fused quartz and fused silica are both made from the same raw material, silicon dioxide (SiO2).
2. they are both very pure glasses with a high silica content and low impurity content.
3. they have very similar physical and optical properties.
DIFFERENCES
1. Fused quartz and fused silica are manufactured by different processes. Fused quartz, whose chemical name is silicon dioxide, is originally made by melting pure quartz crystals at very high temperatures. The manufacture of fused quartz is a complex process that involves melting high purity silicon dioxide in specialized furnaces at temperatures in excess of 2,000°C. This is a very high temperature process. This extreme heat is necessary to ensure that the raw silica is transformed into a homogeneous, non-crystalline state. Fused quartz is processed by fusing powdered crystalline quartz in a hydrogen-oxygen flame and is manufactured to various purity specifications for several specific applications.
Fused silica is amorphous silicon dioxide, often also referred to as synthetic quartz, and is made by using high-purity silica sand manufactured from SiCL4. Silicon tetrachloride (SiCl4) is burned in a hydroxide-oxygen flame, where the oxygen combines with the silicon, the chlorine escapes in the form of HCl, and the synthetic silicon dioxide is deposited in the form of a very fine powder (dust), which can then be fused to obtain a solid material. Fused silica is sometimes called fused quartz or quartz glass. However, it should be remembered that it is an amorphous material while quartz is crystalline.
2.Fused quartz is usually more heat resistant than fused silica and can withstand higher temperatures before it begins to soften. Fused quartz has a high melting point of over 1700°C and can be used at high temperatures (<1050°C) allowing it to withstand extreme temperatures, this is due to the different manufacturing processes that result in different structures and properties of the glass.
3.Fused quartz is usually more transparent than fused silica due to the difference in manufacturing processes. Air bubbles may be trapped in the glass during production of fused silica, resulting in a translucent appearance.
4.Fused silica has a wide range of transparency (approximately 0.18 μm to 3 μm), which allows it to be used not only throughout the visible spectrum, but also in the ultraviolet and infrared regions. However, these limitations depend to a large extent on the quality of the material. For example, for applications in infrared optics, it is necessary to have a low content of hydroxyl groups (OH) - often referred to as water - and it is often required that ir-grade fused silica has an OH content of less than 10 ppm; for applications in the UV spectral region, other properties are relevant, but UV transmission may be limited by various metallic impurities .
Fused quartz has excellent optical clarity, especially in the UV to IR spectrum, with high average transmittance in excess of 80% in the 260nm to 2500nm range. The performance and quality of most fused quartz products is equally dependent on the purity level of the material.
5.Fused quartz is generally stronger and more scratch-resistant than fused silica, which favors applications requiring durable glass materials. This also means that fused quartz is more difficult to work with, as compared to fused silica, which is easier to work with and polish.
6.Fused quartz is more expensive to produce than fused silica because of the difficulty of collecting the components and the manufacturing process itself. Fused quartz is in high demand in the semiconductor and fiber optic industries. Fused silica is used in various optical components such as lenses, prisms, optical planes, reflective substrates and diffraction gratings. The key advantages of fused silica are the broad spectral transmission range, hardness and low thermal expansion, e.g., large telescope mirrors, optical windows.
7.Commonly used fused quartz are GE 124, GE 124 is a very pure fused quartz made from crystallized silicon dioxide. Commonly used fused silica are Corning7980\JGS1\JGS2\JGS3.
MG Optics is a professional optical lens manufacturer with many experienced technical engineers, we specialize in the production and processing of high-precision fused silica lenses, as well as ULE, ZERODUR, RSA6061, SiC and other materials for you to choose from, send us a drawing and get a quote!