CaO-Al_(2)O_(3)-SiO_(2)玻璃显微力学性能研究

Micromechanical Properties of CaO-Al_(2)O_(3)-SiO_(2) Glasses

采用熔融冷却工艺制备了一系列钙铝硅酸盐体系的玻璃,通过维氏压痕测试对玻璃的硬度及抗开裂能力(CR)进行了研究,通过红外及拉曼光谱探究了玻璃结构的变化,特别探讨了SiO_(2)含量和施加荷载对其形变和断裂行为的影响。在进行压痕实验时玻璃的变形有两个不同结果:塑性流动和致密化。塑性(或剪切)流是物质的体积守恒位移,而致密化是非体积守恒的不可逆压缩,在压痕下方产生密度增加的半球形区域。研究结果表明:当SiO_(2)含量减少时,玻璃的原子堆积系数较大,而摩尔体积相对较低,拥有更高的弹性模量,其硬度从6.83 GPa提高至7.22 GPa(载荷为100 gf),但断裂韧性较低,抗开裂能力相对较弱,CR值从330 gf降至190 gf;相反,SiO_(2)含量提高后,在整个压痕过程中参与致密化的SiO_(2)比例更大,玻璃的致密化程度更高,其抗开裂能力越强,这表现在压痕经过退火处理后,压痕的恢复比例提高,表明其残留应力降低的程度越大。

A series of calcium-aluminosilicate glasses were prepared by using melt cooling process.Hardness and cracking resistance (CR) of the glasses were studied by using Vickers indentation test.Structural evolution of the glasses were examined by using infrared spectroscopy and Raman spectroscopy,especially revealing the influence of SiO_(2)content and load on deformation and fracture behavior of the glasses.There are two deformation ways in the glasses during indentation:plastic flow and densification.Plastic (or shear) flow is a volume-conserved displacement,while densification is a non-volume-conserved irreversible compression that produces hemispherical regions with increased density beneath the indentation.When the SiO_(2)content was reduced,the glass has higher atomic packing density,lower molar volume and higher elastic modulus.Hardness of the glasses increases from 6.83 GPa to 7.22 GPa (load:100 gf),but the fracture toughness is lowered and the anti-cracking ability is weakened.CR value decreases from 330 gf to 190 gf.On the contrary,with increasing content of SiO_(2),the densification process is more involved in the whole indentation process and the cracking resistance is enhanced,which is reflected in the indentation after annealing treatment.The recovery ratio of the indentation is increased,indicating the higher degree of residual stress reduction.