Synthesis of ZrN-Based Composites via Nitridation of Zircon + Aluminum Mixtures in Combustion Mode

Self-propagating high-temperature synthesis has been used to nitride zircon with aluminum additions (5–30%). We have examined the influence of the key process parameters (composition of the starting mixture, gas pressure, and sample diameter) on the combustion speed, nitrogen content, and phase composition of the synthesis products and found critical parameters at which combustion was impossible: less than 20% aluminum, nitrogen pressure under 2 MPa, and sample diameter less than 35 mm. The addition of 20–30% aluminum has been shown to change the phase composition of the synthesis products. On the addition of 20–25% Al, the phase composition was ZrN, Al2O3, Si3Al3O3N5, ZrO2, and ZrSi2; at 30% Al, it was ZrN, Al2O3, ZrSi2, Al3O3N5. The combustion products have been shown to contain aluminum oxynitride (Al3O3N5) forming from the gas phase. We have identified the mechanism underlying nitridation of a ZrSiO4 + Al mixture in combustion mode. A composite powder with the composition ZrN–Al2O3–ZrSi2–Al3O3N was tested as a material for producing coatings by nonvacuum electron-beam cladding.