La_(2)O_(3)对镁铝尖晶石透明陶瓷致密化及其性能的影响  

Effect of La_(2)O_(3) on Densification and Properties of Transparent Magnesium Aluminate Spinel Ceramics

作　　者：吕思敏 杨金萍 韩丹 刘梦玮 章健[3] 王士维[3] LYU Simin;YANG Jinping;HAN Dan;LIU Mengwei;ZHANG Jian;WANG Shiwei(College of Materials Science and Engineering,North China University of Science and Technology,Tangshan 063210,China;Key Laboratory of Inorganic Material of Hebei Province,Tangshan 063210,China;The State Key Lab of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 201800,China)

机构地区：[1]华北理工大学材料科学与工程学院,唐山063210 [2]河北省无机非金属材料重点实验室,唐山063210 [3]中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室,上海201800

出　　处：《硅酸盐通报》2021年第8期2719-2725,共7页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金青年科学基金(51902330)。

摘　　要：镁铝尖晶石透明陶瓷兼具了良好的光学和力学性能,在军、民两用领域有着广泛的实际和潜在应用前景。由于其致密化速率低,在烧结过程中往往需要引入烧结助剂。稀土倍半氧化物熔点高,高温不易挥发,近些年被证实可以促进镁铝尖晶石陶瓷的致密化,但其促烧机理尚不明确。本文以高纯商业化镁铝尖晶石粉体为原料,La_(2)O_(3)为烧结助剂,采用无压预烧结合热等静压烧结,制备镁铝尖晶石透明陶瓷,通过XRD、SEM、紫外-可见分光光度计、万能试验机等测试手段对其致密化过程及其力学和光学性能进行表征和分析,研究了La_(2)O_(3)对镁铝尖晶石透明陶瓷致密化过程的影响规律和作用机制。结果表明,La_(2)O_(3)通过与尖晶石反应或固溶产生晶格畸变,增加缺陷浓度,从而起到促进致密化的作用,一定程度上降低了预烧温度和热等静压温度。对于190 MPa、1500℃热等静压烧结3 h的样品,La_(2)O_(3)掺杂可以显著提高紫外区域的透过率;同时,La偏析到晶粒表面,抑制了尖晶石晶粒的生长,从而提高了样品的力学强度。掺杂0.05%(质量分数)La_(2)O_(3)样品较未掺的样品,400 nm处透过率从63%提高到81%,弯曲强度从263.7 MPa提高至319.0 MPa,断裂韧性从1.69 MPa·m^(1/2)提高至1.82 MPa·m^(1/2)。Transparent magnesium alumina spinel ceramics have both good optical and mechanical properties,and have broad practical and potential application prospects in the military and civilian fields.Due to its low densification rate,sintering aids are often introduced during the sintering process.Rare earth sesquioxides have high melting point and are not easily volatile at high temperatures.In recent years,some of them are used to promote the densification rate of magnesium aluminate spinel ceramics,but the sintering mechanism is still unclear.In this work,transparent magnesium aluminate spinel ceramics were prepared through pressureless sintering followed by hot isostatic pressing treatment,using high-purity commercial magnesium alumina spinel powders as the raw materials,and La_(2)O_(3) as the sintering aid.XRD,SEM,UV-visible spectrophotometer and universal testing machine were employed to investigate the effect of La_(2)O_(3) on the sintering and densification process of transparent magnesium aluminate spinel ceramics.The results show that La_(2)O_(3) can result in lattice distortion through reaction with spinel or forming the solid solution at the high temperature,which promotes the densification process of spinel,and reduces the presintering temperature about 40℃.For samples subjected to hot isostatic pressing at 1500℃/3 h at 190 MPa,La_(2)O_(3) doping increases the transmittance in the ultraviolet region.At the same time,La segregates to the grain surface and inhibits the grain growth,which improves the mechanical strength of the sample.Compared with the undoped sample,the transmittance of 0.05%(mass fraction)La_(2)O_(3) doped sample at 400 nm increases from 63% to 81%,its bending strength increases from 263.7 MPa to 319.0 MPa,and its fracture toughness increases from 1.69 MPa·m^(1/2) to 1.82 MPa·m^(1/2).

关 键 词：透明陶瓷 La_(2)O_(3) 镁铝尖晶石 烧结助剂 致密化 晶粒细化 

分 类 号：TQ174[化学工程—陶瓷工业]