Preparation And Properties Of Alumina Ceramics Strengthened And Toughened By Silicon Carbide Nanowires Grown With Foam Holes

Alumina ceramics,as the traditional ceramic material has good corrosion resistance,abrasion resistance,excellent mechanical property to store the advantage of abundant,low cost,is currently the most widely studied a kind of nonmetallic material,but the characteristics of high alumina ceramics fragile low greatly limits its practical application,so crucial for the alumina material toughening reinforcing.Many researchers use whisker,nanowire and fiber toughened alumina ceramics,but the dispersion of nanowire in matrix has always been a difficult problem in this field.This research adopts the efficient and simple particle stable foam porosity up to 96%of Al₂O₃/Si composite foam ceramic,through chemical vapor deposition method in alumina foam ceramic body internal in-situ growth of SiC nanowires,using the in situ growth of SiC foam ceramics nanowires toughening alumina ceramic is a good way to solve the problem of the nanowires dispersion.The effect of SiC nanowires grown in situ on mechanical properties of alumina ceramics was investigated by hot pressing sintering of foam ceramics.SiC-one-dimensional nanowires wire has excellent function,and its strength is obviously higher than its bulk material,so it has great application potential as alumina ceramic reinforcement material.In recent years,in-situ growth of nanowires,whiskers and fibers inside foam ceramics has become a new research direction.The foam ceramics prepared by the traditional process are mainly simple open and closed cell structure.The whisker and nanowires can form a new three-dimensional network pore structure in the foam ceramics,which can better expand the application of alumina foam ceramics.In this experiment,phase composition,microstructure,compressive strength and specific surface area of Al₂O₃/SiCNWs foam ceramics were characterized and analyzed by adjusting the Content of Si and sintering temperature.The results show that the SiC nanowires grow inside the pore wall of foam ceramics at 1350℃,1450℃and 1550℃,and the nanowires grow the most at 1450℃.The pore structure of the nanowires is a new three-dimensional network structure woven on the pore wall.Increasing Si content in raw materials can also increase the growth of nanowires.In addition,it is found that the presence of nanowires changes the brittle fracture mode of alumina foam ceramics,and the SiC nanowires can effectively induce crack deflection.After hot pressing,the phase composition,microstructure,bending strength and fracture toughness of the ceramics were analyzed and characterized by adjusting the hot pressing sintering temperature of the ceramics and adding amount of sintering aid.The effect of in-situSiC nanowires on mechanical properties of Al₂O₃ ceramics was explored.It was found that the mechanical properties of the sample with 2wt%Mg O and 2wt%Y₂O₃ as the composite combustion aid at 1450℃after hot pressing sintering at 1700℃were higher than other samples,and the average bending strength and fracture toughness were 741.61MPa and 5.09MPa·m^1/2.