The AlN-based dielectric composite materials with high resistivity values ​​are promising for use in electronics. However, ensuring a sufficient level of their mechanical characteristics is no less important condition for the practical use of products from these composites. For composites of the AlN-C-ZrB2 and AlN-C-TiN systems with resistivity >10⁹ Ohm, which were manufactured under hot pressing conditions at a temperature of 1900 °C and a pressure of 12 MPa, mechanical characteristics, in particular hardness and fracture toughness, were studied. 

Using a FALCON 500 microhardness tester with an optical camera, the Vickers microhardness was determined at a load of 98 N, and the fracture toughness of composite materials was also calculated taking into account the sizes of cracks emanating from the corners of the pyramid imprint. 

The obtained results of the measurements of the mechanical characteristics indicate a slight decrease in the hardness of the AlN-C-ZrB₂ and AlN-C-TiN composites in contrast to the aluminum nitride composite without additional components. The hardness value of AlN-C-ZrB₂ ceramics is 7.99±0.14 GPa, and AlN-C-TiN ceramics is 8.77±0.48 GPa, while for AlN ceramics the HV value is at the level of 11.34 ± 0.7 GPa. It is noted that for the material with a higher hardness value, the level of fracture toughness is also higher and is 5.01±0.34 MPa•m^1/2, while K_1C for the other composite, like the hardness value, is expectedly lower - 4.68±0.3 MPa•m^1/2. The adding components to aluminum nitride to improve electrodynamic characteristics results in a slight decrease in mechanical characteristics, but their level is high enough to withstand loads during material processing or when operating in vibration conditions.