典型陶瓷岩板的力学性能研究

Mechanical Properties of Typical Ceramic slabs

陶瓷岩板旨在跨界应用于三维家居领域,然而,在如切割或钻孔等后期加工过程中可能会由于裂纹失稳扩展而导致碎裂。断裂韧性是评价陶瓷材料抵抗裂纹扩展能力的关键指标,建陶行业应引入断裂韧性来评价陶瓷岩板的力学性能。为了可靠评价陶瓷岩板的断裂韧性并探究物相组成及显微结构对其影响,首次采用基于超尖V型切口的改良SEVNB法准确测得四种典型陶瓷岩板的断裂韧性值,其范围为1.04~1.35MPa·m^(1/2),并估算出这四种陶瓷岩板的临界裂纹尺寸为79.1~119.4μm。通过物相定量分析发现较多的刚玉和较少的玻璃相有利于提高其断裂韧性;通过显微结构分析发现四种陶瓷岩板的断面不完全致密,气孔分布不均匀,而切割裂岩板断面存在较大尺寸的游离石英晶粒和长度约为100μm的大尺寸裂纹,接近其临界裂纹尺寸估算值108μm,在低应力作用下,裂纹容易失稳扩展导致材料断裂,这是导致陶瓷岩板切割裂的主要原因。

Ceramic slab is designed to be applied in 3D household.However,it may undergo fracture or break due to unstable crack propagation during post-processing such as cutting or drilling.Fracture toughness is a key index to evaluate the crack propagation resistance of ceramic materials,so it should be introduced to evaluate the mechanical properties of ceramic slabs in the building ceramic industry.In order to evaluate the fracture toughness of ceramic slabs reliably,the modified SEVNB method based on ultra-sharp V-notch was used for the first time to accurately measure the fracture toughness values of four typical ceramic slabs,ranging from 1.04 MPa·m^(1/2)to 1.35 MPa·m^(1/2),and the calculated critical crack size of those four ceramic slabs ranging from 79.1μm to 119.4μm.In addition,the effect of phase compositions and microstructure on the fracture toughness of ceramic slabs was investigated based on phase quantitative analysis.It is found that more alumina and less amorphous phase are conducive to the improvement of fracture toughness.The microstructure analysis shows that the fractured surface of four kinds of ceramic slabs are not fully dense,the pore distribution is uneven.Moreover,large size free quartz gains and a large crack of about 100μm can be found in easily cracked ceramic slab,which is close to the calculated critical crack size of 108μm.Under low stress,the crack will be easy to propagate unsteadily resulting in material fracture,which is the main reason for fracture or break of the ceramic slabs.