SiC matrix composites are widely used in high-temperature structural components of aircraft engines and nuclear reactor materials because of their excellent properties such as their high modulus, high strength, corrosion resistance, and high-temperature resistance. However, the bonding of SiCf/SiC composites poses significant challenges in practical engineering applications, primarily due to residual stresses, anisotropy in composite properties, and the demanding conditions required for high-performance joints. This work reviews various bonding technologies for SiC ceramics and SiC matrix composites. These include solid-state diffusion bonding, NITE phase bonding, direct bonding without filling materials, MAX phase bonding, glass ceramic bonding, polymer precursor bonding, metal brazing bonding, and Si-C reaction bonding. Key results, such as the highest bending strength of 439 MPa achieved with Si-C reaction bonding, are compared alongside the microstructural characteristics of different joints. Additionally, critical factors for successful bonding, such as physical mismatch and metallurgical incompatibility, are discussed in detail. Future research directions are proposed, emphasizing the optimization of bonding techniques and evaluation of joint performance in harsh environments. This review provides valuable insights into advancing bonding technologies for SiC composites in aerospace and nuclear applications.

This study systematically investigates the influence of temperature on the defect formation mechanisms in uranium nitride (UN) crystals using first-principles calculations. The formation energies and lattice distortion characteristics of various defects at 0 K and 1780 K were calculated by constructing models of perfect crystals as well as vacancy, interstitial, antisite, and divacancy defects. The results demonstrate that elevated temperatures significantly reduce defect formation energies, with interstitial and divacancy defects exhibiting negative formation energies at 1780 K, indicating a tendency for spontaneous formation. The U interstitial defect induces the most pronounced lattice expansion of 5.1% at 0 K. Furthermore, interstitial defects cause the most significant lattice distortions, while Schottky defects exhibit the lowest formation energy. The current study provides theoretical insights into the defect behavior of UN fuel under high-temperature service conditions and offers valuable guidance for optimizing sintering process parameters.