Metal Casting

Boron nitride’s high chemical resistance against a vast majority of molten metals, combined with excellent thermal shock resistance makes it ideal for a variety of molten metal contact applications. In addition, boron nitride is easily machinable into complex shapes for quick prototyping, offering advantage over traditional ceramics.

Protective Coatings for Molten Metal Contact

Utilization of a Saint-Gobain boron nitride protective coating on refractory surface in contact with non-ferrous molten metals such as aluminum, copper or zinc dramatically extends the life of the refractory system and the efficiency of the metal processing line. Saint-Gobain CeraGlide® SF+ coatings, with an alumina binder system, provide a high-grade protection layer that has strong adhesion, wear resistance and is non-wetted by molten metals in demanding environments.

The contact angle of a molten metal on a surface is a measure of the protection offered by that material. The higher the angle, the better the protection from infiltration and corrosion. With a high contact angle even at elevated temperatures, boron nitride shows excellent resistance to molten aluminum and other metals.

Break Rings for Continuous Casting

Over the past 15 years, horizontal continuous casting of steel and specialty alloys has gained widespread acceptance compared to traditional vertical continuous casting, due to favorable investment cost, small plant footprint, possible high level of automation, and low manpower requirements. Furthermore, possibility of smaller batch sizes offers manufacturers flexibility in offering a wider product range.

One key aspect of horizontal continuous casting is movement of melt without help from gravity from the holding crucible to graphite die and cooler assembly. The melt passes through a graphite die, series of holding components, and finally through a refractory ring (break ring) into the solidification zone. As the melt moves from hot zone to cool zone (solidification zone) and undergoes a sudden change in temperature, it is important that the break ring maintains integrity and allows the melt to continue to move without sticking or building-up at the intersection. Though very simple part of the total assembly, break rings are critical components of a horizontal continuous casting assembly. Any failure or breakage will result into the loss of entire heat, causing safety hazard and significant downtime from part replacement and clean-up.

Saint-Gobain's COMBAT® grade ZSBN offers the properties critical to this application - high thermal shock resistance for uninterrupted flow of melt, low coefficient of friction even at high temperatures for build-up free movement, and corrosion and slag resistance for a variety of metals, alloys and super alloys.

Side Dams for Thin Strip Casting

Thin strip casting of steel and its alloys at or near its final dimensions has gained popularity due to energy savings offered by reduced number of manufacturing steps, as well as reduced carbon footprint compared to traditional slab-casting.

Success of a thin-strip casting run depends on successful containment of steel melt between rotating twin-rolls, using refractory parts called side dams. Uniform thickness of steel strip, and therefore high process yields, depends on a the refractory's resistance to erosion against the moving rolls and corrosion from the molten steel. 

 

Saint-Gobain's COMBAT® grade ZSBN offers the right balance in this application. Addition of zirconia to boron nitride adds the desired wear resistance and high corrosion resistance at operating temperatures upwards of 1400°C.