Ductile Iron Dry Powder Coating For Lost Foam Casting With High Adhesion And Low Gas Generation

2. Ductile Iron

The dry powder coating for lost foam casting is a powder-form foundry coating developed specifically for the lost foam casting process and the production requirements of ductile iron castings. Compared with traditional water-based and alcohol-based coatings, it offers greater formulation flexibility, easier storage and transportation, and improved environmental performance. As a result, it has been increasingly adopted in the large-scale production of ductile iron components.

Core Functions of Ductile Iron Dry Powder Coating:

1.Compatibility with Ductile Iron Pouring Characteristics

The coating features moderate refractoriness (1500–1600 °C), well matched to the pouring temperature of ductile iron (1380–1450 °C). Aggregates such as quartz powder and bentonite are commonly used to avoid adverse reactions with nodulizing and inoculating agents, thereby ensuring stable nodularity and mechanical properties.

2.Low Gas Generation to Prevent Gas-Related Defects

The binder system (e.g., bentonite combined with CMC) exhibits low moisture absorption and generates minimal gas after drying. Together with properly controlled permeability, it allows the smooth evacuation of gases generated during foam pattern vaporization, effectively reducing subsurface porosity and pinhole defects.

3.Strong Adhesion with Easy Peel-Off

The coating demonstrates excellent hang-on properties and uniform wetting of foam patterns. It remains crack-free and firmly bonded after drying. After pouring, the coating peels off easily in flakes, leaving a smooth casting surface and minimizing post-casting cleaning operations.

4.Flexible Process Adaptation with Cost Efficiency

Recommended water-to-powder ratio: approximately 1:0.55–0.65. The coating can be applied by dipping or brushing and is suitable for various ductile iron castings such as crankshafts, valve bodies, and wheel hubs. With a long shelf life and convenient on-site mixing, it is well suited for batch and mass production.