Structural Strength And Fatigue Properties Of Micron Metallic Glasses Mold

Field of MEMS maintains high-speed development recently.On the basis of the higher requirement of structural precision,micro mold fabrication becomes one of the most important problems of polymer micro molding.However,there are some limitations in the existing micro mold processing methods.It is of great significance to find a new method for processing micro mold with high strength,high precision and low cost.Metallic glasses(MGs),not only have shown excellent mechanical properties in the fields such as strength,hardness,wear resistance and so on,but also can be formed into complex graphics like polymer materials with the temperature rises to their SLR.Since they lack the limitation of grain boundary in traditional crystalline metals,MGs can be accurately duplicated patterns on their surfaces in atomic level by micro hot-embossing molding.Then reduce the temperature,MGs can keep these patterns and recover original excellent mechanical,physical and chemical properties.Tg of MGs are usually higher than Tm of polymer materials,which means that MGs can be applied into the field of Micro-Forming.In this paper,researches of micro MGs mold about their structural strength and fatigue properties are described below:(1)Samples of different sizes were cut from Zr41.2Ti13.8Cu12.5Ni10Be22.5(Vitreloy1,shorter for Vit-1)BMG,then polishing the wafer samples with a self-designed polishing device.The surface roughness of polished samples was measured by AFM.XRD verified that MG samples after cutting and polishing were still in amorphous state.Tg and SLR of Vit-1 MG were measured by DSC to prepare for micro hot-embossing molding.Silicon molds with specific patterns in their surfaces were obtained by ICP bulk-silicon processing technology.Using hot-embossing molding to make micro cylinder samples which were prepared for uniaxial static compression experiments and compression-compression fatigue experiments,then characterize the morphology of the samples by SEM and LSCM.(2)Taking a part of samples for annealing treatment.All the samples before and after annealing were characterized using XRD and uniaxial compression tests tocompare the compressive properties.The samples were examined after compression experiment by SEM,and fracture mechanics were analyzed by observing patterns on the fracture surface.(3)Uniaxial compression-compression fatigue experiments were performed on samples which were before and after annealing.Taking 107 times for infinite cycle life.Synthesizing experimental data of the stress and life into S-N curves,then comparing the compressive fatigue properties of samples before and after annealing.The samples were examined after fatigue experiment by SEM,and fracture mechanics of fatigue were analyzed by observing patterns on fracture surface.(4)A large number of MG plates with different sizes were polished by polishing machine to metallurgical state,then duplicating micro patterns into the surfaces of MG by micro hot-embossing molding.Using these MG molds to fabricate polymer microfluidic chips by hot-embossing molding.Using the finite element simulation software COMSOL to predict the service life of the micro mold before and after crystallization with S-N curve from fatigue experiments as a failure criterion.Then forecasting the application of MG micro mold in the sheet metal cold pressing process and predicting their structural strength and fatigue life.