Lanthanum zirconate multiphase ceramic, and preparation method and applications thereof

Abstract

The invention discloses a lanthanum zirconate multiphase ceramic, and a preparation method and applications thereof. The lanthanum zirconate multiphase ceramic comprises lanthanum zirconate and lanthanum aluminate, and lanthanum aluminate is dispersively distributed into lanthanum zirconate. The preparation method comprises the following steps: sintering lanthanum zirconate and lanthanum aluminate mixed powder through discharge plasma, to obtain the lanthanum zirconate multiphase ceramic. The lanthanum zirconate is toughened by lanthanum aluminate in a ferroelastic toughening manner, therefore, the lanthanum zirconate multiphase ceramic has the advantages of being high in fracture toughness, high in density, good in chemical stability and volume stability, and the like, and has wide application prospects in the application field of high-temperature thermal barrier coatings.

Description

Technical field [0001] The invention belongs to the technical field of composite ceramics and its preparation, and in particular relates to a lanthanum zirconate (La 2 Zr 2 O 7 ) Multiphase ceramics and preparation methods and applications thereof. Background technique [0002] Thermal Barrier Coating (TBC) is an advanced ceramic material system, mainly used on high-temperature metal components of gas turbines and aero engines, such as combustion chambers and turbine blades. The most commonly used thermal barrier coating is the traditional 8% mass fraction of yttria stabilized zirconia (8YSZ). With the continuous development of thermal barrier coatings, compared with traditional 8YSZ thermal barrier coatings, lanthanum zirconate is a potential new product due to its lower thermal conductivity, lower oxygen transmission rate, and higher melting point. A generation of alternative coatings. [0003] Compared with the traditional 8YSZ thermal barrier coating, lanthanum zirconate has ...

AI Technical Summary

Problems solved by technology

A lot of research work is carried out around the theme of overcoming brittleness, or toughening. Although there are many research results on the mechanism of toughening ceramics, in fact, there are not many toughened ceramics researched and developed, or even though toughened Composite ceramics are available, but their toughening mechanism is still unclear

In addition, the addition of some toughening phases may cause the thermal barrier coating to undergo volume changes during thermal cycles, resulting in volume mismatch with the matrix, or the toughening phases may occur with the matrix or ceramic base phase at high temperatures. reaction, these phenomena will seriously reduce the service life of the thermal barrier coating

For example, in the prior art, barium titanate is used to toughen lanthanum zirconate, but during the long-term thermal cycle, barium titanate will react with lanthanum zirconate, resulting in coating failure

In another case, lanthanum zirconate toughened by zirconia with tetragonal phase stabilized by yttrium oxide is used to improve the fracture toughness of lanthanum zirconate through phase transformation toughening, but the volume change can easily lead to internal stress in the coating, which promotes cracking of the coating, which is not conducive to heat treatment. Long-term use of barrier coatings

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