宽光谱透过Mg0.9Al2.08O3.97N0.03透明陶瓷的制备与性能研究

MgAl₂O₄透明陶瓷具有优异的光学性能, 但其较差的机械性能和成型过程中的水解问题限制了实际应用, 通过组成设计MgAlON四元尖晶石可以有效调节其综合性能。本研究采用凝胶注模成型、无压烧结和热等静压处理制备了一种具有宽光谱透过范围的新型Mg_0.9Al_2.08O_3.97N_0.03透明陶瓷, 系统比较其与MgAl₂O₄透明陶瓷的光学性能和机械性能, 分析了低应力下裂纹的缓慢扩展并预测使用寿命。研究表明：固相体积分数为50%的陶瓷浆料粘度最低, 为124 mPa·s, 满足凝胶注模成型的需求; 2 mm厚的Mg_0.9Al_2.08O_3.97N_0.03透明陶瓷样品在3.7 μm处的直线透过率达86.2%, 光学透过范围与MgAl₂O₄相比拟, 折射率和阿贝数略高于MgAl₂O₄; 同时, 该陶瓷具有和MgAl₂O₄相近的Weibull模数, 尽管裂纹缓慢扩展系数比MgAl₂O₄小, 但特征强度(210.6 MPa)和惰性强度(227.5 MPa)均高于MgAl₂O₄。包含少量N的MgAlON尖晶石较好地克服了陶瓷粉体的水解问题, 并在保持优越光学性能的前提下显著提高了透明陶瓷的机械性能。本研究为尖晶石型透明陶瓷的制备与性能的改善提供了新的途径。

Preparation and Property of Mg0.9Al2.08O3.97N0.03 Transparent Ceramic with Broad Optical Transmission Range

MgAl₂O₄ transparent ceramics possess excellent optical property, but their practical applications are somewhat restricted by the hydrolysis problem during the shaping process and limited mechanical property. Meanwhile, it has been demonstrated that the property of quaternary MgAlON spinel can be effectively adjusted via varying their composition. Accordingly, a novel Mg_0.9Al_2.08O_3.97N_0.03 transparent ceramic with a broad transmittance range was prepared by combining aqueous gel-casting, pressureless sintering, and hot isostatic pressing treatment. Optical and mechanical property of this transparent ceramic were systematically investigated and compared with those of MgAl₂O₄ transparent ceramic. Furthermore, the slow crack growth under low stress were analyzed, and the service life of transparent ceramic was predicted. It is shown that the viscosity of ceramic slurry with 50% (in volume) solid load was 124 mPa·s, which could meet the requirement of aqueous gel-casting. The in-line transmittance of 86.2% at 3.7 μm was obtained in the Mg_0.9Al_2.08O_3.97N_0.03 transparent ceramic sample with thickness of 2 mm, and the optical transmittance range was comparable to that of MgAl₂O₄, with slightly higher refractive index and Abbé number. Further, this ceramic showed a Weibull modulus similar to MgAl₂O₄, and although its crack slow growth coefficient is lower than MgAl₂O₄, but both the characteristic strength (210.6 MPa) and inert strength (227.5 MPa) were much higher. Therefore, in the quaternary MgAlON spinel with low nitrogen content, the hydrolysis problem of ceramic powders could be well overcome, while the mechanical property of transparent ceramic was remarkably improved without degradation of optical property. This research provides a new pathway toward obtaining the novel spinel transparent ceramics with improved preparation and property.