Custom OEM Milky Quartz Crucible Manufacturers & Exporters

Devitrification is the phase transformation of metastable amorphous fused silica into crystalline cristobalite at sustained temperatures between 1200°C and 1550°C. Premature devitrification is accelerated by three primary catalysts: (1) Trace surface alkali contamination—specifically Sodium (Na), Potassium (K), and Calcium (Ca)—acting as nucleating agents; (2) Mechanical abrasive scratches or dust particles adhering to the inner wall prior to silicon loading; and (3) Inadequate vacuum atmosphere with oxygen leakage inside the furnace chamber. Nivra Quartz prevents this by enforcing raw sand beneficiation with total alkali metal limits under 1.2 ppm and sealing all crucibles in vacuum packaging within a class-10,000 cleanroom.

The composite crucible structure balances thermal and chemical demands. The opaque milky outer layer contains controlled micro-bubbles (20–80 μm) that diffuse radiant energy, preventing localized heater hot-spots from directly transferring to the silicon charge. Conversely, the inner layer (typically 2 to 4 mm thick) must be nearly 100% transparent and bubble-free. If bubbles exist near the inner wall, the corrosive molten silicon dissolves the thin silica membrane, releasing gas bubbles into the melt. These bubbles get trapped in the freezing crystal ingot, ruining single-crystal yield.

Yes. As an OEM and ODM manufacturer, our engineering team regularly fabricates bespoke crucibles, cylindrical liners, flat-bottom melting dishes, and rectangular sintering boats. You can provide 2D mechanical drawings (PDF/DWG) or 3D solid models (STEP/IGES). We evaluate critical dimensional tolerances, draft angles, corner radii, and wall thickness gradients, returning a formal DFM (Design for Manufacturability) review and quotation within 5 business hours.

For standard crucibles ranging from 14 to 32 inches, our standard tolerance for outer diameter (OD) is ±1.0 mm to ±1.5 mm, height ±1.5 mm, wall thickness ±0.8 mm, and out-of-roundness (ovality) ≤ 1.5 mm. For high-precision semiconductor crucibles and oversized 36"+ formats, precision CNC graphite tooling can tighten OD tolerances down to ±0.8 mm with bottom curvature profile deviations maintained within ±0.5 mm to match the susceptor's parabolic contours perfectly.

For standard catalog crucibles and high-temperature fused quartz accessories, our MOQ is as low as 1 to 5 pieces for pilot qualification runs. Small machined quartz components (wafers, discs, rings) typically carry an MOQ of 10 to 50 pieces. Custom prototypes can be engineered, cast, annealed, and shipped within 10 to 14 business days, while volume container orders usually take 20 to 25 calendar days.

Packaging is an engineered discipline at Nivra Quartz. Each crucible is degreased, baked to remove ambient moisture, and hermetically sealed in heavy-gauge antistatic polyethylene bags with desiccant. The unit is then suspended inside form-fitted, high-density expanded polyethylene (EPE) shock absorption foam that cushions the rim and base against multi-axis shocks. Finally, the assembly is housed in IPPC-certified fumigation-free engineered plywood crates with internal reinforcement ribs and external impact-indicator sensors.

Our milky quartz crucibles operate continuously up to 1150°C to 1250°C without external mechanical support. When contained within a precision graphite susceptor (as in typical CZ pulling furnaces), they operate reliably at molten silicon bath temperatures of 1450°C to 1550°C for continuous cycles. The maximum softening point of fused SiO&sub2; is approximately 1683°C. Heating ramp rates of up to 15°C to 20°C per minute are routinely accommodated due to the extremely low coefficient of thermal expansion (5.5 × 10−7 /°C).

Fused quartz demonstrates near-total inertness across almost all acids (including HCl, HNO&sub3;, H&sub2;SO&sub4;, and aqua regia). However, it will corrode rapidly if exposed to Hydrofluoric Acid (HF) even at room temperature, and Phosphoric Acid (H&sub3;PO&sub4;) at temperatures above 150°C. Additionally, molten alkaline hydroxides (NaOH, KOH) and basic metal oxides react directly with the acidic SiO&sub2; network at elevated temperatures, forming soluble silicates and degrading crucible structural integrity.