What are the key steps in the production process of pure calcium wire?

　　I. Raw Material Preparation and Pre-treatment

　　The first step in the production of pure calcium wire is the selection and processing of raw materials, a stage that plays a decisive role in product quality.

　　Selection of High-Purity Calcium Ingots: For the production of pure calcium wire, calcium ingots with a purity of 98% or higher are used as raw materials. Calcium ingots are typically prepared by electrolysis or thermal reduction; among these methods, electrolytic production yields ingots of higher purity. The content of impurity elements such as iron, aluminum, and silicon in the raw material is strictly controlled, as these impurities can adversely affect the mechanical properties and metallurgical performance of the calcium wire.

　　Surface Treatment: The surface of calcium ingots typically features an oxide or nitride layer, which must be removed through mechanical grinding or chemical cleaning. This step is critical for subsequent processing performance, as surface contaminants can lead to fracture during the drawing process.

　　Preheating Treatment: Calcium ingots must be preheated at 150–200°C for 2–4 hours prior to processing to relieve internal stresses and enhance ductility. Preheating is typically carried out under an argon or nitrogen atmosphere to prevent oxidation of the calcium upon exposure to air.