A novel porous mullite ceramic with overlapping and interlocking mullite whiskers was prepared using in-situ whisker growth technology. Without using any pore-foaming agents, the formation of a porous structure was facilitated by the atomic rearrangement of Al₂O₃ and SiO₂ catalyzed with MoO₃. The effects of the molar ratio of Al₂O₃ to SiO₂, MoO₃ content, sintering time, and sintering temperature on the structure and properties of various (xAl₂O₃·ySiO₂)_m(MoO₃)_n-T-t ceramics were comprehensively studied. The molar ratio of Al₂O₃ to SiO₂ had a more significant impact on the morphology of whiskers, while the other three conditions generally promote whisker growth. Under conditions of x:y=3:1.8, m:n=9:1, T=1300℃, and t=3 h, (3Al₂O₃·1.8SiO₂)₉(MoO₃)₁-1300℃-3h ceramics exhibited a satisfactory compressive strength of 4.81 MPa at a density of 0.76 g/cm³. Microstructural analysis revealed that a multi-level reinforcement structure was obtained by the interlaced distribution of tiny and large whiskers, significantly increasing the crack deflection area and enhancing the crack deflection resistance when resisting external forces. After 100 thermal shock cycles between room temperature and 1300℃, the compressive strength retention rate was 77.13 %. Besides, the multi-scale whisker overlapped structure also has a high specific surface area (1.83 m²/g), high porosity (74.18 %), and smaller pore size (7.44 μm). The thermal conductivity was as low as 0.260 W·m^-1K^-1, and the ceramic maintained a rear-side temperature below 200°C when subjected to a 1300°C butane flame. In addition, the regulatory mechanism between parameters, structure, and properties was analyzed in detail, providing data support for the research of porous material.

High-temperature-resistant adhesives are critical materials in the aerospace field. The zirconium-modified aluminum phosphate-based adhesives developed in this work had the advantage of adjustable thermal expansibility, achieving a high matching of coefficient of thermal expansion (CTE) with alumina. The introduction of zirconium can significantly improve the thermal stability of the adhesive matrix, and the Zr/Al ratio substantially affects the various reaction processes inside the adhesive, especially the types of zirconium-containing compounds. Most of the zirconium-containing compounds in the A7Z3 adhesive were ZrO₂ only when the mass ratio of zirconium hydroxide to aluminum hydroxide was 3 : 7, which was the key reason why it had the highest CTE. The room-temperature bonding strength of A7Z3 after heat treatment at 1500 °C reached 67.2 MPa. After pretreatment at 1500 °C, the high-temperature bonding strength of A7Z3 was greater than 50 MPa in the range of (room temperature) RT–1000 °C. After 40 thermal cycles between RT and 1500 °C, the bonding strength still reached 10 MPa. Physical bonding occurred at temperatures below 1000 °C, while chemical bonding dominated above 1000 °C based on the generation of Al₅BO₉ and mullite at the interfaces.