Toughening Optimization And Helium Irradiation Resistance Of SiC-ZTA/ATZ Composite Ceramics

The complex phase ceramics of ZTA20wt%(20% of ZrO2 volume),ATZ80wt%(80% of ZrO2 volume),SiC20 v.%-ZTA20wt% and SiC20v%-ATZ80wt% composite ceramics were prepared from alpha-Al2O3,ZrO2 and beta-SiC powders by discharge plasma sintering(SPS).On this basis,the conventional properties of ceramics,including mechanical properties and thermal properties,were analyzed and studied,and the effects of different preparation parameters on the properties of the complex phase ceramics were studied.According to the service environment of the material,appropriate irradiation conditions were selected to evaluate the irradiation resistance of the material.The main conclusions are as follows:1.Microstructure study: XRD results showed that only-al2o3 and ZrO2 existed in ZTA and ATZ ceramics;The presence of-Al2O3,ZrO2,and-sic in the SiC doped ceramics,and the absence of other heterophases indicate that-sic is chemically stable during sintering.SEM results show that the addition of appropriate amount of SiC can inhibit the gromolh of matrix grains and play a role in refining the grains.When the fracture toughness is high,the composite phase ceramics are dominated by transgranular fracture.2.Mechanical properties study: the bending strength of SiC-ATZ80wt%composite phase ceramics decreased from 992 MPa to 761 MPa with the increase of SiC content,mainly because the thermal expansion mismatch between SiC and substrate of the additive phase introduced thermal stress,resulting in different shrinkage between the substrate and SiC affecting its strength;In addition,when SiC is distributed at the grain boundary,the diffusion path of atoms and vacancies along the grain boundary is larger than the particle size of SiC,so the diffusion along the grain boundary becomes slow and the strength decreases.However,the bending strength of SiC-ZTA20wt% series multiphase ceramics first increased and then decreased,mainly due to the weakened inhibitory effect of SiC-ZTA20wt% series on3.matrix grains.In the case of multiphase ceramics,SiC,due to the hindering effect of its particles,can effectively increase the fracture toughness of multiphase ceramics by deflecting the crack at the tip and acting on the overseas Chinese.The high toughness of ZrO2 particles and their interaction with the matrix make the fracture toughness of ATZ80wt% series higher than that of ZTA20wt% series.4.The thermal performance study: duplex ceramic thermal diffusion coefficient and thermal conductivity is proportional to the content of SiC,is inversely proportional to the content of ZrO2,from room temperature to 200 ?,the heat capacity of the duplex ceramic with temperature rise rate faster,then gradually slow,temperature increase leads to the phonon mean free path decreases,and the coefficient of thermal conductivity decreases.5.Study on the irradiation resistance of SiC20 v.%-ZTA20wt% Depth effect:when the irradiation damage was 50 dpa,the size of the helium bubble in the doping peak area(3.8-4.1 m)was significantly larger than that in the front-end damage area(0-3.8 m),and there was no significant difference in the size and density of the helium bubble with the depth in the front-end area.Dose effect: under the same depth,the temperature is 800 ?,the damage level of 50 dpa helium bubbles in the sample is significantly greater than the one of 5 dpa,it indicates that the higher the incident He ion dose is,the easier it is to aggregate and grow up.Temperature effect: The same depth,the damage level of 50 dpa,the size of helium bubble in the 800 ? irradiation samples is significantly greater than the one of the room temperature irradiation samples,show that high temperature can accelerate the growth of helium bubble.6.Comparison of anti-irradiation performance: under the same irradiation parameters,the size of helium bubble in SiC20 v.%-ZTA20wt% is obviously smaller than that in ZTA20-wt%.Meanwhile,The surface of SiC-ZTA20wt% samples was observed under metallographic microscope.The results show that SiC-ZTA multiphase ceramics have better ability to resist He ion irradiation.