Q: How to make boron nitride coating?

A: Boron nitride coatings can be produced without any refractory binder; the adherence of the particles can be achieved with their surface energy alone. Specific surface areas of at least 25m2/g are necessary for this. Most applications, however, require a coating with reasonable adherence which makes the use of refractory binders necessary. For coating ceramic substrates with low thermal expansion, phosphate-containing binders have proven to be well suited. These binders harden when heated to 800 ... 900°C and result in a strong yet brittle bond. They cannot be used for high-thermal-expansion substrates like metals. Here binders on the basis of Al2O3 for higher temperatures (>1000°C) or Al2O3-SiO2 for temperatures below 1000°C can be used.

In order to use boron nitride in cast houses and foundries it is necessary to apply in the form of coatings. In most cases these coatings are water-based suspensions like house paint. These boron-nitride-coatings are applied like ordinary house paints by brushing or dipping. If it is required to coat small objects, dipping can be an application method of choice as well. Spraying is also possible and is recommended for coating larger surfaces and for hot objects which are difficult to paint. For spraying, a blow cup or a spray gun operated by pressurized air can be used. Nozzle sizes of 1.5mm will give best results.

Recommend product: H-BN-A, H-BN-B, H-BN-C

• Hexagonal Boron Nitride (II)