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Opaque Quartz Tubes

Opaque Quartz Tubes

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Introduction

Opaque Quartz Tubes (also known as Milky White Fused Silica or Satin Quartz) are specialized products characterized by their translucent, non-transparent appearance, achieved through a controlled manufacturing process that introduces microscopic bubbles within the quartz structure. This structure is not a defect but a feature: it excels at scattering and diffusing light and heat, transforming concentrated radiant energy into highly uniform, gentle heat distribution. Yancheng Mingyang Quartz Products Co., Ltd. produces these tubes primarily for high-temperature furnace applications, especially in the semiconductor and solar industries, where temperature uniformity across the process zone is paramount for high yield. The material retains the core benefits of fused quartz—high temperature resistance (∼1100∘C) and exceptional chemical purity (SiO2​≥99.9%)—while offering dramatically improved thermal radiation characteristics compared to clear quartz.

These tubes act as essential liners or sleeves in horizontal and vertical furnaces, shielding the sensitive wafers or ingots from direct, uneven thermal radiation from the heating elements. The diffusive property ensures that the heat reaching the process load is balanced, preventing thermal stress and resulting in uniform crystal growth or uniform film deposition. We offer a full range of standard and large diameter opaque tubes with tightly controlled wall thicknesses to ensure predictable thermal performance. The surface finish is typically a smooth, satin texture, which we can customize with further grinding for tight-fitting furnace collars and seals. While opaque quartz has slightly lower purity than synthetic clear quartz, it is still significantly purer than most ceramics and metals used in high-temperature applications, making it suitable for many high-purity thermal processes.

For buyers concerned with maximizing the throughput and quality of their high-temperature batch processes (e.g., silicon wafer diffusion), our opaque quartz tubes are a key enabling technology. We provide comprehensive data on the thermal emissivity and transmission properties of our various opaque grades, allowing process engineers to select the optimal material for their specific heating profile and application.

Specification Parameters

ParameterDetails
Material TypeOpaque Fused Silica (Milky White Quartz)
Purity (SiO2​)Min. 99.9% (High chemical resistance maintained)
Outer Diameter (OD) Range50 mm to 500 mm (Commonly large diameter for furnaces)
Wall Thickness (WT)3 mm to 10 mm (Customizable for strength/insulation)
Dimensional Tolerance (OD/WT)Standard ±1.0 mm; Tight tolerance available on request
Max Operating Temperature1100∘C (Continuous); excellent thermal stability up to 1250∘C
Optical PropertyHigh Diffusivity / Low Transparency (Scatters radiant heat)
End FinishCut, Ground, or Flanged (Fusion welded for sealing)

The technical performance of our Opaque Quartz Tubes is fundamentally linked to their internal microstructure. The dispersed micro-bubbles act as scattering centers, efficiently diffusing the intense infrared heat generated by surrounding heating elements. This creates a homogeneous thermal environment inside the tube, which is essential for uniform temperature profiles. We strictly control the concentration and size of these bubbles during the fusion process to ensure consistent Optical Property (diffusivity) across large batches. While the purity is slightly lower than clear synthetic quartz, it is carefully controlled to prevent metallic contaminants that could leach into the process environment. The tight dimensional control, especially on the Outer Diameter, is critical when these large tubes are used as the furnace liner, requiring a precise fit within the furnace shell to maintain insulation and thermal efficiency. We perform full CMM (Coordinate Measuring Machine) inspections on the ends to ensure accurate fit for flanging or collar connections. The inherent low CTE of quartz is retained in the opaque form, providing excellent thermal shock resistance despite the larger size and higher operating temperatures, minimizing the risk of costly process interruptions due to tube failure.

Applications

  • Semiconductor Diffusion and Oxidation: Used as the outer liner in vertical and horizontal high-temperature furnaces to ensure highly uniform heat distribution around the silicon wafers.

  • Photovoltaic (Solar) Crystal Growth: Essential component in CZ and FZ crystal pulling furnaces, where the uniform radiant heat is crucial for the slow, defect-free growth of silicon ingots.

  • High-Temperature Annealing: Serving as the main process chamber for annealing large metal or ceramic components in a chemically inert environment.

  • Infrared Radiant Heaters: Used as the outer envelope for specialized industrial heaters where a soft, even, large-area heat output is required (e.g., drying or preheating large panels).

  • High-Temperature Insulators: Employed as durable, high-purity thermal barriers and supports in furnace systems that require protection from direct heat contact.

  • Gas Discharge Lamp Envelopes: Used in certain high-intensity lighting or UV lamp designs where diffused light and high operating temperature are required.

The key benefit in application is the thermal homogeneity they create. In a semiconductor furnace, the difference between success and failure often lies in the 1∘C temperature difference across a 300 mm wafer. Opaque quartz tubes solve this problem by scattering and absorbing the heat, then re-radiating it gently and uniformly to the wafers. This prevents thermal runaway and stress fractures in the crystal lattice of the silicon. Furthermore, the material's structural stability at high temperatures means that the tube does not sag or deform over extended periods of use, which is critical for maintaining the precise alignment inside the furnace. We offer custom fabrication of end caps, boat supports, and specialized collars from the same opaque quartz material, allowing clients to build a complete, integrated thermal system that guarantees maximum purity and performance coherence.

Advantages

  • Superior Thermal Uniformity: Excels at diffusing and scattering IR heat, creating a highly uniform temperature profile inside the tube, which dramatically improves yield in semiconductor and crystal growth processes.

  • High Operating Temperature: Maintains structural integrity and thermal performance up to 1100∘C continuously, making it suitable for the most demanding furnace applications.

  • Excellent Thermal Shock Resistance: Low CTE characteristic ensures the tube resists cracking even during rapid cooling or heating cycles inherent in batch processing.

  • High Purity Barrier: Provides a clean, high-purity SiO2​ barrier between the process media and the metallic furnace heating elements/shell, minimizing contamination.

  • Structural Stability: Does not sag or deform under load at elevated temperatures, ensuring long-term maintenance of critical furnace geometry.

  • Cost-Effective for Large Dimensions: Offers a high-performance, high-purity, high-temperature solution that is economically viable for manufacturing large diameter components compared to exotic ceramics.

The decision to use our opaque quartz tubes is driven by the need for process control in high-value manufacturing. The diffusive heating property is an engineered feature that directly addresses the challenges of large-scale thermal processing. By manufacturing the opaque material in-house, we ensure consistency in the bubble structure and density, which translates directly to predictable thermal performance batch after batch. Our ability to supply custom-ground ends and fusion-welded components made from the same opaque material simplifies the furnace design and reduces potential failure points. We offer technical consultancy to help clients optimize their furnace design, leveraging the unique thermal properties of opaque quartz to achieve superior process results, often leading to significant improvements in end-product quality.

Payment and Shipping

We accept secure international payment methods, including T/T and L/C, for the procurement of these specialized tubes. Given their high value and frequent use in bulk industrial furnace installations, we offer advantageous contract pricing and flexible scheduling for long-term supply relationships.

Shipping Protocol for Large Diameter Tubes: Packaging is designed to protect the structural integrity and surface quality of the heavy, large-diameter tubes.

  • Robust Crating: Tubes are packed into IPPC-certified wooden crates with custom-cut supports and foam padding to prevent movement and impact damage during sea or air freight.

  • Surface Protection: The ends and external surfaces are protected from abrasion during transport to preserve the integrity for sealing.

  • Global Logistics: We facilitate efficient global shipping, often via sea freight for large, heavy orders, providing comprehensive customs documentation and tracking from dispatch to final delivery at the client's industrial site.

Lead times for large diameter, opaque quartz tubes vary from 4−8 weeks depending on the OD and specific fabrication required (e.g., flanging or slots). We guarantee timely communication regarding production status.

Frequently Asked Questions (FAQ)

  • Q: How does opaque quartz achieve better temperature uniformity than clear quartz?

  • A: Clear quartz transmits radiant energy directly. Opaque quartz contains micro-bubbles that scatter and absorb the radiant heat (IR), then re-radiate it gently and evenly across its entire surface. This thermal buffering and diffusing action eliminates the intense "line-of-sight" heating, resulting in a significantly more uniform temperature field inside the tube.

  • Q: Can opaque quartz tubes be used in vacuum applications?

  • A: Yes, despite the internal micro-bubbles, the exterior and interior walls of the tube are solid fused quartz. The tubes can be sealed or flanged using standard techniques and maintain high vacuum integrity suitable for most furnace processes.

  • Q: What is the maximum OD you can manufacture for an opaque quartz tube?

  • A: Our current drawing capabilities allow us to produce opaque quartz tubes up to OD600 mm, supporting the largest generation of semiconductor and solar furnaces. Custom large diameters may be possible upon consultation.

  • Q: Is the opacity consistent throughout the tube length and wall thickness?

  • A: Yes, the manufacturing process is highly controlled to ensure uniform distribution of the micro-bubbles, guaranteeing consistent opacity, wall thickness, and thus, predictable thermal performance across the entire length and all units within a batch.

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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