Production of Si₃N₄-Based Articles and their Application in Aerospace Industry

Abstract

As required by the purpose and operating conditions of the articles, Si3N4-based ceramic materials must have a combination of properties ensuring their serviceability, while their manufacturing process must afford the manufacture of complex-shaped products. The paper deals with the technology of making complex-shaped articles from reaction-bonded, densified silicon nitride in the system Si3N4, Si3N4-BN, Si3N4-Al2TiO5, Si3N4–Si by thermoplastic slip casting of a fine high-purity silicon powder comprising additives or sintering aids with subsequent nitridation at temperatures up to 1500°C or additional sintering up to 1750-1800°C. In the process of making reaction-bonded silicon nitride, consideration is given to the exothermal effect of reaction, to the influence of additives on the properties of ceramics and the manufacturing process. Methods of oxidation protection of porous Si3N4-based ceramics and adaptation of these methods to protection of porous SiC- or SiC-C – based ceramics are discussed. Upon densification of reaction-bonded silicon nitride at temperatures up to 1750- 1800°C, consideration is also given to the effects of diffusion processes of the additives, used as sintering aids, on ceramics microstructure. The mechanisms of dissolution – recrystallization of α- and β-Si3N4 in the course of forming the self-reinforced ceramic structure are discussed. The peculiarities of making Si3N4-Si – based material having unusual properties including the mechanism of forming, oxidation resistance, electrical conductivity and high impact resistance are covered. The paper presents the results of testing of the ceramic components and units of gasturbine engines, bearings and attachments of the spacecraft Buran, and it also gives test data with reference to the ceramic parts tested at temperatures above 2000°C.

Spark plasma sintering of α-Si3N4 ceramics with Al2O3 and Y2O3 as additives and its morphology transformation

“…It is also important to develop high performance Si 3 N 4 ceramics against corrosion attack at high temperatures. All these factors have attracted considerable attention from the academic and industrial communities [2][3][4].…”

Additive manufacturing of silicon nitride ceramics: A review of advances and perspectives

“…Cappi et al 68 prepared an aqueous Si 3 N 4 ink with a solid loading of 30 vol.% and manufactured high-performance complex-shaped Si 3 N 4 ceramics by DIW successfully. The sintered Si 3 N 4 ceramic part had a density of 3.18 g/cm 3 , a hardness value (HV .2) of 17, and a fracture toughness K IC of 4.4 MPa m 1/2 , respectively. In their further study, 69 they obtained dense and delamination-free Si 3 N 4 and MoSi 2 samples as well as multilayer parts (as shown in Figure 7A [reproduced with permission from Ref.…”

“…Silicon nitride (Si 3 N 4 ) ceramic has been widely applied in military, mechanical engineering, aerospace, and biomedical fields, such as missile radomes, 1 rocket nozzles, 2 turbine and automotive engine components, 3 tool bits, 4 wearresistant bearings, hip or knee endoprosthetic implants, and dental implants, 5 owing to its promising combined properties of excellent mechanical properties, thermal shock resistance at elevated temperatures, good dielectric properties and biocompatibility [6][7][8][9][10] (as shown in Figure 1). At present, the demand for high-performance complex-shaped Si 3 N 4 ceramic components in different applications is increasingly urgent, which has attracted the interest of many researchers.…”