Mainstream Plating Types for Mold Copper Tubes

1. Chromium Plating: A long-standing traditional choice for mold copper tubes, chromium plating is valued for its high hardness and strong resistance to the constant friction and scouring from hot molten steel. However, chromium and copper have notably different expansion and contraction rates with temperature changes, often causing the chromium layer to peel over time. Modern techniques address this with a two-layer system: a nickel-cobalt alloy buffer (matching copper’s expansion) under chromium. Even if chromium is damaged, the alloy layer protects, letting the tube handle ~30% more steel than traditional single-layer chromium plating.

1. Nickel-based Alloy Plating: Alloys like nickel-cobalt and nickel-iron resist wear well in mold tubes’ demanding environment. Adjusting metal ratios enhances heat resistance—for example, a nickel-cobalt alloy with 15%–20% cobalt stays hard at 800℃. It also adheres 2–3 times better than pure chromium, suiting fast continuous casting where reliability and durability are crucial.
2. Functional Composite Plating: This innovative type incorporates tiny particles (e.g., silicon carbide, alumina) into the layer, enhancing wear resistance and heat insulation. It reduces heat transfer from molten steel by 10%–15%, preventing cracks from extreme temperature swings and preserving the tube’s structural integrity over time.

Key Functions of Plating for Mold Copper Tubes

1. Resisting High-Temperature Wear: The hard plating forms a robust barrier against rapid wear from the rubbing between solidifying steel and the tube wall. Chromium plating, for instance, is 5–8 times more wear-resistant than unplated tubes, reducing replacements and cutting downtime and maintenance costs significantly.

1. Protecting Against Molten Steel Damage: Molten steel has elements like iron and manganese that react with copper, forming brittle deposits. The plating acts as a shield, blocking these reactions to prevent slag buildup, spot erosion, and other damage that could compromise performance.
2. Ensuring Even Heat Distribution: Uniform plating thickness—especially at R corners—ensures even heat spread. Special additives keep R corner thickness variation below 5%, a big improvement over older methods’ 15% variation. This avoids cast steel cracks, ensuring higher quality end products.