Study On The Mechanism Of Sepiolite Nano Fibers Reinforced Ceramics

The ceramic material,as an important branch of the global material industry,is widely used in many areas such as daily appliances,construction and health,electrical,chemical,mechanical,information and aviation.It is because of its rich raw materials,simple production process and excellent performance.Ceramic material has many advantages that can not be matched by other materials.But the ceramic material has a fatal weakness that is its brittleness.This shortcoming seriously affects the further development of the ceramic material.Aiming at this problem,the crystal phase and morphology of sepiolite under high temperature,the mechanism of sepiolite nano-fibers reinforced ceramics and the sintering kinetics of sepiolite reinforced ceramics were studied.These provide theoretical and experimental bases for the application of sepiolite nano-fibers in the field of ceramics.First,the sepiolite nano fibers calcined at different temperatures and sintered sepiolite minerals were tested by TG-DTA,XRD,SEM and TEM.Then,according to the test results,the sepiolite ore was determined to be divided into four groups and calcined at room temperature,300?,600?and 900?respectively.The treated sepiolite nano-fibers were then added to the ceramic green body and the addition amount was set to 0,1wt%,2wt%,3wt%and 4wt%.After molding through the dry pressing method,the samples were sintered at 1150?,1200?and 1250?respectively.Finally,the mechanical properties of the samples were characterized by three-point bending method and unilateral incision beam method.The microstructures of the samples were characterized by XRD and SEM.The sintering kinetics of sepiolite nano-fibers reinforced ceramics was calculated by the linear shrinkage.The experimental results show that the sepiolite nano-fibers can maintain the fiber morphology after calcining at high temperature,although the crystal phases have changed.When the sintering temperature is 1200?and the amount of untreated sepiolite is 2wt%,the flexural strength of the ceramic body reaches a maximum of 144.5 MPa and the fracture toughness reaches a maximum of 4.51 MPa·m^1/2.Under the same conditions,the mechanical properties of the ceramics without sepiolite nano-fibers are increased by 24.6%and 81.1%,respectively.The added sepiolite ore nano-fibers form diopside fibers in the sintered ceramic matrix.The mechanism of sepiolite nano-fibers reinforced ceramics is mainly three kinds:one is the bridging effect of the fibers;the second is the crack deflection effect;the third is the weak interface formed between the fiber and the matrix.With the increase of the content of sepiolite nano-fibers from 0 to 4wt%,the value of sintering activation energy increases from 23.60 to 35.45 kJ/mol.This indicates that the densification process of sepiolite nano-fibers reinforced ceramics is mainly controlled by diffusion mass transfer.