The production process of zirconium rods involves core links such as raw material purification, melting, plastic processing, precision forming, and quality inspection. The specific process is as follows:
1、 Raw material purification and melting
Preparation of sponge zirconium
Zirconia ore (such as zircon) is used as raw material to generate zirconium tetrachloride (ZrCl ₄) through high-temperature chlorination, and then sponge like metal zirconium blocks with a purity of ≥ 99.6% are obtained through magnesium thermal reduction method.
Using vacuum distillation technology to remove residual impurities (such as MgCl ₂, magnesium), the final oxygen content is ≤ 500ppm, and the hardness is ≤ 100HB.
Vacuum melting
Mix sponge zirconium with alloy elements (such as tin and niobium) and press them into electrodes. After two melting processes in a vacuum consumable electrode arc furnace, a zirconium alloy ingot with uniform composition is formed.
Nuclear grade zirconium rods need to strictly control the content of more than 20 impurities such as hafnium (Hf) and boron (B) to ensure stable nuclear performance.
2、 Plastic processing
Hot rolling and forging
Hot rolling process: Ingots are rolled into billets at high temperatures (800-1000 ℃), suitable for conventional industrial zirconium rod production.
Forging forming: Refining grain size through forging process to improve mechanical properties (such as tensile strength ≥ 550MPa), suitable for high-strength demand scenarios such as nuclear reactor structural components.
Cold processing technology
Cold rolling or cold drawing processes improve the surface accuracy of zirconium rods (roughness ≤ Ra0.8 μ m), and control the processing specifications before the finished product (such as deformation and heat treatment temperature) to optimize corrosion resistance and mechanical properties.
3、 Precision Forming and Surface Treatment
Precision machining
The cold drawing process is used to produce high-precision zirconium rods with diameters ranging from Φ 1 to Φ 350mm, and the tolerance can be controlled within ± 0.02mm.
Irregular cross-sections (square, hexagonal) are achieved through mold extrusion or CNC machining.
Surface protection
During high-temperature processing, inert gases (such as argon) should be used for protection to prevent zirconium from reacting with gases such as oxygen and nitrogen to form brittle compounds (such as ZrO ₂, ZrN).
4、 Quality Inspection and Packaging
Non destructive testing
Ensure that there are no cracks, pores, or other defects inside the zirconium rod through ultrasonic testing, X-ray inspection, and other methods.
Nuclear industry grade products need to additionally meet ASME IX standards to inspect weld strength, corrosion resistance, and other indicators.
Packaging and transportation
Zirconium rods with a diameter of ≤ 10kg are packaged in wooden boxes, while large-sized products (≥ 50kg) are reinforced with wooden pallets. During transportation, they must be moisture-proof and shock resistant.
