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Low-OH Fused Silica

Low-OH Fused Silica

-- Steady & Reliable Manufacturer --

Introduction

Low-OH Fused Silica refers to high-purity quartz glass where the hydroxyl (OH) radical concentration has been intentionally reduced to extremely low levels, typically below 10 ppm, and often as low as 1 ppm or less. This reduction is critical because OH groups are the primary cause of signal attenuation (light absorption) in the infrared (IR) spectrum, specifically creating a strong absorption peak around 2.7 μm and a secondary peak at 1380 nm. Yancheng Mingyang Quartz Products Co., Ltd. uses a specialized vacuum fusion and drying process to produce Low-OH fused silica, making it the ideal material for high-temperature applications and IR optics where water contamination is detrimental to performance. The material retains all the excellent properties of standard fused quartz, including chemical inertness and low thermal expansion, while dramatically improving IR transparency and high-temperature stability.

The presence of OH is often associated with elevated levels of devitrification (crystallization) at high temperatures (∼1100∘C). By producing Low-OH material, we significantly increase the maximum service temperature and the resistance to devitrification, extending the lifespan of components like furnace tubes, reactor liners, and high-temperature apparatus. In IR optics, the Low-OH content is non-negotiable for systems operating above 2.0 μm, such as thermal imaging windows, CO2​ laser optics, and long-wavelength sensor windows. We offer Low-OH material in various formats, including rods, tubes, plates, and custom fabricated components. Every batch is verified using FTIR spectroscopy to accurately measure the OH concentration, providing clients with certified material quality. The superior thermal and optical performance of our Low-OH fused silica is highly valued in the semiconductor, aerospace, and advanced material research sectors where high temperature stability and IR transparency are essential process requirements.

We provide a reliable supply of this specialized material, essential for pushing the limits of high-temperature processing and optical performance in the infrared and telecommunication bands.

Specification Parameters

ParameterDetails
Material TypeLow-Hydroxyl (OH) Fused Silica
Hydroxyl (OH) ContentGuaranteed <10 ppm; Ultra-low grades <1 ppm
Measurement MethodCertified by Fourier Transform Infrared Spectroscopy (FTIR)
Infrared TransmissionHigh transparency in the IR band, significantly improved transmission past 2.0 μm
Max Operating TempEnhanced stability, max 1250∘C (Increased devitrification resistance)
Devitrification ResistanceSuperior resistance to crystallization compared to high-OH quartz at high heat
Trace Purity (Fe, Na, K)Also maintained at low ppm/ppb levels (High Purity Grade)
Available FormsTubing, Rods, Plates, Custom Fabricated Labware and Furnace Components

The most critical technical specification is the verified Hydroxyl (OH) Content which we certify using FTIR spectroscopy. The low OH level directly translates into two key functional benefits. Firstly, it provides high Infrared Transmission in the critical 2.7 μm region, essential for IR sensors and certain laser systems (e.g., Er:YAG laser energy at 2.94 μm). Secondly, the Low-OH content dramatically improves the Devitrification Resistance. OH groups act as catalysts for the nucleation and growth of crystalline quartz (cristobalite) on the surface at high temperatures. By removing the OH, the operating life of high-temperature components (furnace tubes, crucibles) is extended, especially when exposed to contaminants that also promote crystallization. The Max Operating Temp is practically increased because the failure mechanism due to devitrification is delayed. This feature is highly valued in the semiconductor industry for diffusion and CVD furnace liners that operate above 1150∘C for extended periods. We ensure that our Low-OH material also maintains high overall purity, as determined by ICP-MS, to eliminate any metallic contamination risk to the client’s process.

Applications

  • Semiconductor Diffusion and CVD Furnaces: Used as process tubes, liners, and load boats where high temperature stability and resistance to devitrification over long cycles are necessary.

  • Infrared (IR) Optics: Employed as lenses, windows, and prisms for IR cameras, thermal imaging equipment, and IR laser delivery systems operating above 2.0 μm.Optical Fiber Preform Cladding: Used as a low-OH cladding layer over a pure core to eliminate the 1380 nm absorption peak, ensuring low-loss telecommunications fiber.

  • High-Temperature Chemical Reactors: Used in specialized vessels and apparatus where materials are processed at extreme heat and where OH leaching or surface crystallization cannot be tolerated.

  • CO2​ Laser Optics: Serving as output windows or beam splitters for high-power CO2​ lasers (operating at 10.6 μm), though its primary benefit is in the near to mid-IR.

  • Astronomical Telescope Blanks: Used as mirror blanks for telescopes where thermal stability is paramount and high IR transmission may be required.

The strategic advantage of using Low-OH fused silica is the inherent reliability and extended life it provides in high-temperature, IR-sensitive applications. For the semiconductor industry, the improved devitrification resistance means furnace tubes can run for longer campaigns without replacement, reducing maintenance costs and downtime. In IR optics, the superior transmission opens up new windows in the IR spectrum that are completely blocked by high-OH quartz, enabling higher fidelity and longer-range IR sensing. We can custom fabricate complex Low-OH quartzware, such as specialized furnace end caps or multi-zone reactor vessels, ensuring that the entire apparatus benefits from the low OH thermal stability. Our ability to process both natural and synthetic quartz into Low-OH grades allows clients to select the optimal balance of purity and cost for their specific application—natural for furnace applications, synthetic for critical IR optics.

Advantages

  • Superior IR Transmission: Eliminates the strong absorption peaks at 2.7 μm and 1380 nm, enabling high-performance IR optics and low-loss fiber optics.

  • High Devitrification Resistance: Dramatically increases the component lifespan and reliability of quartzware used in continuous operation at temperatures above 1100∘C.

  • Increased Max Operating Temperature: Improved thermal stability allows for higher peak operating temperatures without structural degradation.

  • Reduced Thermal Distortion: The low OH content further enhances the material's structural integrity and thermal homogeneity under high heat.

  • Certified Quality: FTIR measurement ensures and certifies the exact low OH concentration for mission-critical components.

  • Versatile Forms: Available in all primary raw material and custom fabricated forms, allowing full apparatus construction in the Low-OH grade.

The central advantage is the material engineering that provides both excellent optical performance in the IR and extended thermal life. This dual benefit solves major reliability problems in both the semiconductor and optical industries. Our controlled fusion process ensures that the low OH value is homogenous throughout the material, not just on the surface. We provide competitive pricing for large-scale production orders of Low-OH tubing and plates, positioning us as a premier supplier for $\text{OEM}$s who depend on this specialized material property.

Payment and Shipping

We accept standard international payments (T/T, L/C). For specialized, high-value Low-OH material, we may require a deposit to cover the cost of the dedicated, highly controlled manufacturing process required to achieve the low OH value.

Shipping Protocol: Care is taken to prevent surface contamination and breakage.

  • Protected Packaging: Components are cleaned, individually sleeved, and secured in cushioned boxes or crates to prevent damage.

  • Moisture Control: The material is often vacuum-sealed or packaged with desiccants to prevent any possibility of surface OH re-absorption (moisture collection) during long transit times.

  • Documentation: Every shipment includes the dimensional QC report and the FTIR certificate verifying the Low-OH content.

Lead times for Low-OH products are typically 4−6 weeks due to the specialized fusion, drying, and annealing cycles required to achieve and stabilize the low OH concentration.

Frequently Asked Questions (FAQ)

  • Q: How does Low-OH quartz resist devitrification better?

  • A: OH groups (Si-OH) act as bond-breaking impurities in the SiO2​ glass network, making it easier for the SiO2​ structure to rearrange into the crystalline phase (cristobalite) at high temperatures. Removing the OH makes the glass structure more stable and resistant to this crystallization process.

  • Q: Is there any difference in chemical resistance for Low-OH fused silica?

  • A: The chemical resistance (to acids/alkalis) remains essentially the same as high-purity quartz—excellent. The main functional difference is the improved IR transmission and high-temperature stability.

  • Q: Why is the 1380 nm peak so important in fiber optics?

  • A: The 1380 nm wavelength is close to the 1310 nm optical transmission window used for high-speed data. A strong 1380 nm peak would leak into the 1310 nm window, causing unacceptable signal loss in telecommunication fibers. Low-OH quartz eliminates this peak.

  • Q: How do I measure the OH content of my existing quartz components?

  • A: You need to use an FTIR spectrophotometer. The OH content is determined by measuring the magnitude of the absorption band centered at 2.73 μm (∼3650 cm−1) according to established industry standards. We offer this measurement as a QC service.

From Made-in-China to
Global Smart Manufacturing

Yancheng Mingyang Quartz Products Co., Ltd. is a company specializing in the production of quartz and special glass products. Yancheng Mingyang Quartz Products Co., Ltd. is the production plant of Jinzhou Mingde Quartz Glass Co., Ltd. in Jiangsu, Since its establishment, the company has developed rapidly, introduced advanced technology and production equipment at home and abroad, and continuously improved and improved product quality. Relying on its own advantages, we have developed a variety of products suitable for the market and meet the needs of different customers, and solved many urgent production problems for our customers.

The company's products include quartz glass tubes, double-hole quartz glass tubes, quartz glass rods, quartz sheets, sapphire windows, calcium fluoride glass windows, infrared ultraviolet coatings, high-pressure resistant aluminosilicate glass window panels, quartz glass instruments, high borosilicate glass instruments, quartz crucibles, quartz gold-plated tubes, quartz heaters, quartz infrared heating tubes, far-infrared directional radiation heaters ultraviolet germicidal lamps and other special types of quartz glass products.

Yancheng Mingyang Quartz Products Co., Ltd.
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