Anisotropic alumina ceramics with isotropic optical properties
作者机构:World Lab.Co.Ltd.Nagoya 456-8587Japan
出 版 物:《Journal of Advanced Ceramics》 (先进陶瓷(英文))
年 卷 期:2023年第12卷第1期
页 面:72-81页
核心收录:
学科分类:08[工学] 0805[工学-材料科学与工程(可授工学、理学学位)] 080502[工学-材料学] 0703[理学-化学]
主 题:alumina anisotropy isotropy fracture toughness(KIC) optical ceramics grain boundary phase
摘 要:Excellent mechanical and isotropic optical properties are achieved simultaneously from fully dense polycrystalline advanced alumina ceramics with a hexagonal crystal structure,which are optically anisotropic.A small amount(240 ppm)of ZrO_(2) additive is used to synthesize the transparent alumina ceramics with an average grain size of 0.7µm,and locally detected optical distortion(birefringence)is extremely minimized,less than 20 nm/*** transmittance(86%)of the alumina ceramics(thickness=0.3 mm)in ultraviolet(UV)to infrared(IR)regions is similar to that of commercial c-axis sapphire single crystals produced by Czochralski(CZ)method,while the extinction ratio in the visible wavelength area is over 25 *** glass and the c-axis sapphire single crystals,the alumina ceramics can clearly display texts and images on liquid crystal display(LCD)screens.A grain boundary phase of nano-sized Al_(2)O_(3)-ZrO_(2) composition(amorphous)is formed at the grain boundary of the advanced alumina ceramics,which enhances four-point bending strength and fracture toughness(KIC)simultaneously to 921 MPa and 6.8 MPa·m^(0.5),respectively,and hence the mechanical properties are superior to those of the sapphire single crystals.