Research On Micro-nano Indentation Test Of Single Crystal Rutile?TiO₂?

Single crystal rutile?TiO₂?is a wide bandgap semiconductor.It has many excellent properties such as high refractive index and birefringence,good near-infrared band transmission,and is widely used in many important technical fields,such as Photocatalysts in solar cells,as optical coatings,biocompatible bone implants,and gate insulators for MOSFET devices,are widely used in modern optical communications,digital equipment,science and technology,and medical instruments.At the same time,single crystal rutile?TiO₂?is very popular among researchers because of its ease of fabrication into single crystal,thin film,and polycrystalline forms.Therefore,conducting mechanical performance tests on single crystal rutile?TiO₂?and exploring its mechanical deformation mechanism are important to optimize the design of various instruments and improve the stability of the equipment.Based on the wide application prospects of single crystal rutile?TiO₂?and the characteristics and advantages of nanoindentation test technology,the significance of using nanoindentation test method to study the mechanical properties of single crystal rutile?TiO₂?is expounded.The typical data analysis method of nanoindentation test-contact stiffness-contact depth method is Oliver-Pharr analysis method.The mechanical model of Oliver-Pharr analysis method and the analysis program for processing the original data are explained.The nanoindentation test device is briefly introduced.Single-phase rutile?TiO₂??100?,?110?,?001?three-dimensional crystal planes were tested with a commercial indenter at room temperature for nano-indentation tests to obtain single-crystal rutile?TiO₂??100?,?110?The load-pressure-depth?ph?curves of?001?crystal directions under different maximum loading loads are analyzed for the hardness,elastic modulus,and elastic-plastic energy of the three crystal planes.The analysis results show that the hardness and elasticity of the three crystal planes The order of the magnitude of the modulus is?001?>?110?>?100?.The hardness and elastic modulus of the?001?crystal plane are significantly higher than the hardness and elastic modulus of the other two crystal planes,and the three crystal planes are plastic.The exponential relationship is?100?>?110?>?001?,which indicates that the?001?crystal plane has better elastic recovery ability during the indentation process.Finally,the model of geometrically necessary dislocations for single crystal rutile is used.The effect of indentation size is analyzed.Taking the hardness under different maximum loading load of the?100?crystal plane as an example,it shows that the model can well explain the dependence of the hardness of single crystal rutile?TiO₂?on depth,that is,small indentation.Inherently large strain gradients Where the dislocations necessary,resulting in a single crystal rutile?TiO₂?increased hardness.The indentation morphology of single crystal rutile?TiO₂??100?,?110?,and?001?was observed by scanning electron microscopy,and different crystal planes were combined with the crystal structure of single crystal rutile?TiO₂?.The deformation and damage mechanisms were analyzed and studied,and the root causes of the differences in the hardness and elastic modulus of the three crystal planes?100?,?110?,and?001?were explained,that is,different slips were activated during the pressing process.However,the activation of different sliding systems requires different critical shear stresses of different sizes and directions.The mechanical properties of the crystal such as hardness,elastic modulus,and fracture are closely related to the critical shear stresses of the sliding system.The method of adjusting the relative position of the indenter and the sample to perform the nanoindentation test on the same crystal plane was used to study the anisotropy of single crystal rutile?TiO₂?.This method not only saves research resources,but also studies the same crystal The mechanical properties of different relative positions of the surface provide a reference for the scientific research and production and processing of single crystal rutile?TiO₂?to choose a more reasonable and economical research scheme and processing method.