Preparation And Mechanical Properties Of Fiber Reinforced Porous Alumina Ceramics

In this paper,alumina fiber reinforced porous alumina ceramics were prepared by freeze-casting method.By exploring the sintering time,fiber content and fiber length on porous ceramic shrinkage,porosity,structural wavelength,fiber bridge number,and compression performance,the interaction law of fiber and solid-liquid interface during freezing process is analyzed,and the fiber is clarified.Formation mechanism of bridge structure and fiber reinforced hole wall structure.Analysis of the compression mechanical properties and modifications of porous ceramics,exploiting the effects of fiber bridge joint structural properties on porous ceramics.The main conclusions are as follows(1)With the increase of fiber content,the volume shrinkage and height shrinkage of alumina fiber reinforced porous alumina ceramics increase,while the porosity decreases slightly.The pore size first decreases and then increases.When the fiber content is 10%,the compressive strength of fiber reinforced porous alumina ceramics is 12 MPa.With the increase of the average fiber length,the fiber morphology in porous alumina ceramics changes from half bridge structure to fiber bridge structure,and the number of fiber bridges increases.(2)The interaction between fiber and solid-liquid interface front was studied.Because of the heterogeneity of the fiber,the attraction fη of the ceramic slurry on the front of the solid-liquid interface increases,and the smaller the angle between the fiber and the solid-liquid interface is,the greater the attraction fη is.Fiber is easy to be engulfed by solid-liquid to form fiber bridging structure.(3)Fiber reinforced porous Al2O3 ceramic failure mode is mainly brittle fracture of the hole wall.The fiber bridge structure can effectively connect the ceramic wall,and the fiber reinforcing hole structure has the effect of inducing crack change path.Pure fiber multi-hole Al2O3 ceramics in the compression process,the fibers slide,friction,and the fiber node breakage causes the sample to be partially deformed,and the sample is faded.