Microstructure and Crystallization Kinetics of Silica-Based Ceramic Cores with Enhanced High-Temperature Property

Abstract

Silica-based ceramic cores play key roles in the casting of aeroengine blades, but they are highly limited by the poor high-temperature mechanical property. Here, fused mullite (FM) and sintered mullite (SM) powders were modified in silica-based ceramic cores, and the microstructure evolution and crystallization kinetics of ceramic cores depending on mullite types were studied. The ceramic cores with FM showed a dense microstructure and superior mechanical properties compared to those with SM. The ceramic cores with 10 wt.% of FM showed a crystallization activation energy of 1119.5 kJ/mol and a crystallization exponent of 1.74, and the values of 938.4 kJ/mol and 1.86 as SM were employed; the decreased crystallization activation energy and the elevated crystallization exponent by SM suggested that the excess impurities of alkali oxides and alkaline-earth oxides significantly promoted the crystallization of cristobalite. Even though the ceramic cores with mullite powders decreased slightly in the room-temperature mechanical property, their high-temperature flexure strength and creep deformation resistance were enhanced. The ceramic cores with 10 wt.% of FM showed excellent comprehensive performance, with linear shrinkage of 0.69%, room-temperature strength of 18.9 MPa, and high-temperature strength of 15.5 MPa, which satisfied the demands for hollow-blade casting.

Preparation of Ceramic Fiber Threads with Enhanced Abrasion Resistance Performance

“…Among diverse organic abrasion-resistant modifiers, polyurethane (PU) is characterized by excellent abrasion resistance and good bonding properties, and it has been applied as coatings and adhesives in various fields such as architecture, textiles, and automobiles [34][35][36][37][38]. The single-component waterborne polyurethane (WPU) is one common PU material; it is easy to adjust its concentration in aqueous solutions, and it can solidify into a film with adjustable softness and hardness at room temperature [39,40]. Additionally, WPU exhibits strong interfacial bonding with various materials, such as ceramics and organic compounds, making it a highly promising and competitive abrasion-resistant modifier.…”