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Quartz Ingots and Blocks

Quartz Ingots and Blocks

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Introduction to Bulk Fused Quartz Ingots and Blocks

Fused quartz ingots and blocks represent the raw, fundamental form of high-purity silicon dioxide (SiO2​) from which precision components are later fabricated. These bulk materials are crucial for manufacturers requiring large-scale, stress-free blanks for final machining into complex shapes, particularly in the optics, semiconductor, and aerospace industries. We provide both large fused quartz ingots (cylindrical or near-net-shape structures created by direct melting) and sawn blocks (cut from larger stock) in various grades, including high-purity natural quartz (JGS2/JGS3) and ultra-pure synthetic quartz (JGS1). The ingot manufacturing process is strictly controlled to minimize internal defects, such as bubbles, striae (internal stress lines), and inclusions. This attention to detail ensures that when the final product is machined, it possesses optimal mechanical strength and optical homogeneity. Large blocks are essential for fabricating oversized components that cannot be easily produced from standard tubing or rod stock, such as large diameter photomask substrates, massive viewport windows for deep-sea or space applications, and thick quartz rings for specialized furnace reactors. The quality of the final precision component is entirely dependent on the quality and internal structure of the initial bulk ingot or block. We provide pre-annealed material to minimize residual stress before machining, which is crucial for preventing cracking during subsequent cutting and grinding. Our high-purity blocks are often required for components that need to maintain purity under sustained high temperatures, ensuring minimal outgassing or contamination risk. We offer custom-size blocks to minimize material waste during machining, providing an economical solution for high-value component production. Furthermore, we offer technical consulting to help clients select the ingot grade (based on OH content and UV/IR requirements) that best suits their final application, guaranteeing structural and optical integrity from the raw material stage onwards.

Structural and Purity Specifications for Bulk Quartz

The quality control for bulk quartz ingots and blocks focuses on internal material characteristics rather than surface finish, which is achieved later in the fabrication process.

Parameter General Ingot Grade Optical/Synthetic Grade Block Tolerance/Remark
SiO2​ Purity (Min) 99.99% 100.00% Required for contamination-sensitive applications.
Total Metallic Impurities <50ppm <20ppb (ICP-MS Verified) Ensures ultra-low leaching and high UV transmission.
Homogeneity (Refractive Index) Low Stress Birefringence Δn<5×10−6 Crucial for high-resolution optical applications.
Bubble Inclusion Density <10bubbles/cm3 Bubble-Free (Zero-Inclusion) Prevents light scatter and structural weakness.
Striae/Stress Lines Controlled (Annealed) Minimally Observable (High-Energy Laser Grade) Stress affects machining and optical quality.
OH (Hydroxyl) Content 50ppm to 500ppm Controlled Low or High OH Determines IR/UV performance and devitrification.
As-Cut Tolerance ±5mm (Rough Cut) ±1mm (Pre-Grinding) Allows for safe machining envelope.
Dimensions (Max) Up to 1500mm Diameter Custom Sawn to 1000×1000×200mm Limits depend on furnace capability.

The most critical internal specification is Homogeneity and the control of Stress Birefringence. Stress in the ingot, if not relieved through proper annealing, can cause the material to fracture during sawing or grinding and will introduce optical distortion (polarization effects) in the final product. Our blocks are subject to a slow, controlled annealing process over several days to ensure the residual stress is minimized, especially important for large pieces. Bubble Inclusion Density is also a primary concern; optical applications require virtually bubble-free material to prevent light scattering and energy absorption. The Purity Grade determines the final use: Synthetic (JGS1) blocks with ppb-level contamination are reserved for the most advanced semiconductor photomasks and deep UV optics. Natural quartz blocks (JGS2/JGS3) are suitable for furnace linings and large industrial viewports. We provide clients with ultrasonic testing reports to verify the internal structure, confirming the absence of large inclusions and verifying the homogeneity of the material before shipment. This ensures that the high investment in a large block of quartz is protected by certified internal quality, leading to high yield in the customer's subsequent machining steps.

Primary Use as Feedstock and Final Components

Bulk quartz ingots and blocks are primarily used as raw material for further processing or as massive structural components where size is a factor.

  • Large-Format Optics and Windows:
    • Telescope Blanks/Optics: Machined into large, precise lenses, prisms, and mirrors for high-resolution astronomical and surveillance systems.
    • High-Pressure/Vacuum Viewports: Fabricated into thick, large-diameter discs required for critical observation ports in scientific or defense chambers.
  • Semiconductor Lithography:
    • Oversized Photomask Substrates: Blocks are precision-machined into the perfectly flat, low-defect plates required for the reticles used in the exposure systems.
  • Industrial Furnace Construction:
    • Large Rings, Flanges, and Spacers: CNC machined into complex, high-purity components for lining large-diameter CVD/Epitaxy reactors and horizontal furnace systems.
  • Fiber Optics Manufacturing:
    • Preform Rods: Large cylindrical ingots are drawn down to form the core or cladding of high-bandwidth, high-purity optical fiber.
  • UV Curing and Sterilization:
    • High-Power UV Lamp Envelopes: Custom-shaped blocks machined to create complex lamp housings or reflectors for high-intensity UV curing systems.

For custom, non-standard component geometries that cannot be economically created by fusing smaller pieces of quartz, starting with a monolithic block is the only viable method. This ensures that the final component is free from weld lines, which can introduce stress and purity discontinuity. We support highly complex 5-axis CNC machining, utilizing our ingots as the feedstock to produce intricate parts with internal channels, precise mounting features, and extreme flatness requirements, particularly for the aerospace and defense sectors where zero failure is tolerated. The block format guarantees maximum purity and structural homogeneity throughout the entire cross-section of the finished product.

Manufacturing and Structural Advantages

Utilizing our high-quality quartz ingots and blocks provides fundamental advantages in component fabrication and end-use performance.

  • Zero-Weld Monolithic Integrity: Starting with a solid block eliminates the need for welding multiple pieces, guaranteeing a monolithic component free from weld-induced stress, bubbles, or localized purity variations, which is essential for high-power laser and deep-UV optics.
  • Superior Optical Homogeneity: Our carefully controlled fusion process minimizes internal striae and stress birefringence (Δn<5×10−6), ensuring that the finished optical element will not distort the wavefront or compromise beam quality.
  • Custom Size and Near-Net-Shape Availability: We can produce ingots and blocks in massive sizes and custom geometries, enabling the production of oversized components while significantly reducing the amount of waste material and machining time required by the customer.
  • Verified Internal Purity: Independent lab verification (ICP-MS) confirms ultra-low trace element levels in our synthetic blocks, providing the highest level of contamination control for the most sensitive applications (e.g., SEMI grade materials).
  • Stress-Relief Annealing Guarantee: All bulk material is subjected to a proprietary slow-cooling annealing process, guaranteeing minimal residual stress (birefringence), which prevents cracking during customer machining and improves the long-term dimensional stability of the final product.
  • Excellent Raw Material Source: The bulk form factor provides the most cost-effective way to source large quantities of high-purity SiO2​ for secondary processing, such as drawing fiber preforms or pulling high-quality optical rod stock.
  • High Thermal Shock Resistance: The low coefficient of thermal expansion, combined with internal structural integrity, ensures that large quartz components fabricated from these blocks can safely withstand extreme, rapid thermal cycling without damage.

We focus on providing a superior, stress-free starting material that maximizes the efficiency and yield of our clients' high-precision machining and fabrication processes.

Purchasing, Payment, and Secure Logistics

Given the size, weight, and high value of quartz ingots and blocks, the logistics require specialized planning and execution.

  • Payment Terms: Due to the large cost associated with bulk fusion and material purification, a 30% to 50% advance payment (T/T) upon order confirmation is typically required to initiate the ingot production cycle. The balance is due upon successful Pre-Shipment Inspection (PSI) and prior to dispatch. Negotiated credit terms are available only for high-volume, long-term OEM contracts.
  • Specialized Packaging: Ingots and blocks are heavy, fragile, and valuable. They are secured in custom-built, heavy-duty wooden crates that feature internal foam padding and structural reinforcement to prevent movement and absorb significant impact. Crating is designed for fork-lift handling and stacking during sea freight.
  • Shipping Logistics: For large, heavy blocks, Sea Freight under FOB (Free On Board) or CFR (Cost and Freight) terms is the standard. We coordinate with major global freight carriers experienced in handling oversized, fragile industrial cargo. Air freight is available only for smaller, high-value synthetic blocks requiring urgent delivery. Full cargo insurance is mandated to cover the high replacement value of the bulk material.
  • Manufacturing Lead Time: The production of large ingots and the subsequent annealing process is time-consuming. Typical lead times range from 4 weeks for standard blocks to 8-12 weeks for massive, high-homogeneity synthetic ingots used for optics, due to the lengthy fusion and controlled cooling cycles.
  • Documentation and Traceability: Every bulk shipment is accompanied by a Certificate of Analysis (CoA) detailing the purity and OH content, and a Certificate of Conformance (CoC) verifying the dimensions and annealing state (residual stress level), ensuring full traceability and compliance with raw material specifications for high-tech manufacturing.

Essential Frequently Asked Questions

  • Q: What is the main benefit of ordering a near-net-shape ingot?

    A: A near-net-shape ingot is fused or molded to closely match the final component's size and geometry (e.g., a large ring with an inner hole). This significantly reduces the amount of expensive quartz material that must be removed through machining (waste), lowering the total fabrication cost and minimizing the customer's machining time. This is particularly cost-effective for large components or those with complex hollow features.

  • Q: How does striae in a quartz block affect the final component?

    A: Striae are microscopic variations in the refractive index within the quartz caused by slight inconsistencies during the fusion process. If the block is machined into an optical component (like a lens or prism), striae will distort the light passing through it, causing issues like beam deviation or non-uniform focal points. For high-precision optics, striae must be minimized, necessitating the use of high-homogeneity, synthetic ingots that undergo very slow, controlled fusion.

  • Q: Why is annealing so critical for quartz ingots before machining?

    A: Annealing is the slow, controlled cooling of the fused quartz. It is critical because the rapid cooling of large ingots creates internal stress (residual stress). If this stress is not relieved, the act of cutting or grinding the block can cause a brittle fracture or cracking, destroying the expensive material. Proper annealing minimizes residual stress (measured as low birefringence), guaranteeing the ingot's stability during the customer's fabrication process.

  • Q: Can quartz blocks be used for high-power laser optics?

    A: Yes, provided they are made from high-purity synthetic fused silica (JGS1) and are certified as bubble-free with low striae and stress birefringence. The ingot must be manufactured to ensure internal homogeneity and purity, as these factors directly relate to the component's Laser Induced Damage Threshold (LIDT). Optical components for high-power lasers are one of the highest-demand applications for our top-tier synthetic quartz blocks.

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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