Study of the reactions between boron carbonitride and refractory metals and compounds

Conclusions

• 1. We investigated the contact interaction between boron carbonitride and tungsten, zirconium carbide, niobium carbide and lanthanum hexaboride in vacuum of 0.133–0.0133 N/m² within the temperature range of 1000–2100°C.

• 2. The presence of contact reaction between the boron carbonitride and tungsten at a temperature above 1800°C was established. The phases formed on the tungsten were identified as W₂B,α-WB,β-WB. Furthermore, the presence of free carbon in the reaction products was established.

• 3. A contact reaction between boron carbonitride and zirconium and niobium carbide and also lanthanum hexaboride was not observed up to 2100°C.

• 4. It was found in the study of the interaction between boron carbonitride and the above-listed materials and also in control tests when it was heated in vacuum that boron carbonitride changes in composition, which is expressed in a color change (the boron carbonitride darkens) and properties (the electrical resistance decreases). A partial decomposition of the component phases of the carbonitride obviously takes place; the free carbon content increases so that the resistance of the material decreases.