Boron Nitride Ceramics Used in Metal Casting

Introduction

Quality materials are crucial for precision and durability in metal casting. Recently, boron nitride ceramics have gained attention in this field, especially in the production of aluminum and other non-ferrous metals. This article is going to discuss why and where boron nitride ceramics are used in metal casting. Hope that you can have a deep understanding of the benefits and uses of boron nitride at the end of it.

What Are Boron Nitride Ceramics?

Boron nitride has excellent thermal stability, chemical resistance, and low coefficient of friction. It can be classified into three categories based on its structure and properties: hexagonal boron nitride (h-BN), wurtzite boron nitride (w-BN), and cubic boron nitride (c-BN), as shown below [1]. Boron nitride's advantages make it ideal for high-temperature applications where other materials might fail, such as in metal casting.

Figure 1. Cubic Boron Nitride, Hexagonal Boron Nitride, and Wurtzitic Boron Nitride

Advantages of Boron Nitride Ceramics Used in Metal Casting

--Low Coefficient of Friction

Boron nitride ceramics are typically used as a mold release agent or a coating for the mold in metal casting. This is because boron nitride ceramics have a low coefficient of friction, which allows for easy release of the metal from the mold.

--Great Thermal Performance

For one thing, boron nitride ceramics can withstand temperatures up to 1800°C. For another, their thermal shock resistance gives them the capability to bear rapid heating and cooling. With such excellent thermal properties, boron nitride ceramics components can withstand the high temperatures generated during the metal casting process without degrading or breaking down.

--High Chemical Resistance

Another reason for using boron nitride ceramics in metal casting is their good chemical inertness to corrosion and oxidation. They do not react with acid and alkali and remain inactive in most molten metals and semiconductors. Therefore, they are suitable for use in harsh chemical environments such as high corrosion or oxidation.

--Non-wettability to Molten Metals

Most importantly, boron nitride ceramics could resist chemical attacks from molten metal. This is particularly significant in the production of aluminum and other non-ferrous metals, which can react with traditional mold materials and cause defects in the final product. By using boron nitride ceramics, manufacturers can avoid these issues and produce high-quality metal parts with minimal defects.

Related reading: Features and Common Products of Boron Nitride Ceramics

Examples of Boron Nitride Ceramics Employed in Metal Casting

Let’s talk about some specific applications of boron nitride ceramics applied to metal casting.

• BN ceramics are widely employed for aluminum extrusion to manufacture coatings for dies to prevent dust during handling and storage. Hard rust would create marks on the surface and scratch the inside. Using boron nitride coatings can protect dies and promote the extrusion process.
• BN coatings are suited for metal forming and shaping procedures. You can find them coated on components like nozzles, plugs, and tubes. Their unique properties help prevent contamination, carburization, and scratches, making them useful for high-temperature applications.
• There are several different forms of boron nitride ceramics used in metal casting. The most common form is hexagonal boron nitride (h-BN), which has a high level of crystallinity and is commonly used as a mold release agent. Another form, cubic boron nitride (c-BN), has a higher hardness than h-BN and is used as a coating material for the mold. Besides, amorphous boron nitride (a-BN) is a non-crystalline form of the material that is used as a lubricant and release agent.

Conclusion

Overall, the use of boron nitride ceramics in metal casting offers several benefits, including improved thermal stability, chemical resistance, and ease of release from the mold. As the demand for high-quality metal parts continues to grow, the use of boron nitride ceramics is likely to become even more widespread in the metal casting industry.

Advanced Ceramic Materials (ACM) provides boron nitride ceramics of different sizes and shapes. Customized BN coatings and parts are also welcome. For more information, please check our homepage.

Reference:

[1] Stutzer, R. (2010). Swift Heavy Ion Irradiated Boron Nitride With and Without Application of High Pressure [Photograph]. https://www.researchgate.net/publication/41170242_Swift_Heavy_Ion_Irradiated_Boron_Nitride_With_and_Without_Application_of_High_Pressure