Boron Nitride is a good self-lubricated ceramic that can withstand high temperatures (2200°C in an inert atmosphere) and maintain its lubricating capability in a high vacuum environment. Boron nitride guide has very low wettability with metal. Compared with graphite, it’s an excellent choice for high-temperature metal spray.
Also, boron nitride ceramic is a kind of refractory ceramic with low expansion and high thermal conductivity. This makes it to be an ideal choice for molten metals.
It’s very easy to be machined to custom design with precision and tight tolerance because of its machinability.