Research On The Dynamic Thermal Mechanical Properties Of TC4 Titanium Alloy Micro-arc Oxidation Films

Mechanical properties of micro-arc oxidation coatings at present stage research include elastic modulus, hardness, micro friction wear, corrosion resistance, high temperature oxidation resistance, etc. However, The micro-arc oxide film layer usually worked under the thermal- mechanical coupling conditions in the practical application, so the research about dynamic thermal mechanical properties of micro-arc oxide film layer under the condition of thermal- mechanical coupling is very important.In this dissertation, the change rule of energy storage modulus, loss modulus and damping dynamic physical characteristics of TC4 titanium alloy micro-arc oxide film layer was studied by the dynamic thermal mechanical analyzer under different temperature and load frequency, microstructure of the membrane layer was observed by scanning electron microscope under the certain condition of thermal- mechanical coupling, so we can study the dynamic thermal mechanical properties of micro-arc oxide film layer under the condition of thermal- mechanical coupling. The results show that:By studying the micro-arc oxidation film thickness on its dynamic thermal mechanical properties, found that the film thickness of 20μm with the highest energy storage modulus and the minimum loss modulus, damping, and peak corresponds to the highest temperature, the microstructure damage is minimal; Thickness of 10μm with the biggest area surface membrane layer falling off, plenty of cross section morphology of crack across the membrane layer, surface crack are also constantly extend outward; when the film thickness is 27μm、33μm, micro-arc oxidation film layer is also a large area of spalling, membrane layer section is mainly from the surface longitudinal crack expand to the substrate. The results showed that when film thickness is 20μm, which has the best dynamic thermal mechanical propertiesBy studying the temperature on the micro-arc oxide film layer dynamic thermal mechanical properties, found that with the increase of temperature, the energy storage modulus, loss modulus of micro-arc oxidation film is rising, when heating temperature reached to 300℃, energy storage modulus, loss modulus decreased with the increase of temperature, and damping have opposite change rules. Observing microstructure of membrane layer found film still keep a good structure in 200℃, and a small amount of micro cracks appeared in the surface in 300℃, with the increase of temperature, range of surface crack is bigger, and the matrix crack spreading speed is faster.By studying the load frequency on the micro-arc oxide film layer dynamic thermal mechanical properties, found that the influence of the matrix of the dynamic physical characteristics showed a trend of single increase with the increase of loading frequency, and dynamic physical characteristics of samples with micro-arc oxidation film coating showed the maximum value at 150 Hz. By studying the membrane layer microstructure under different loading frequency, found that loading frequency main influencing micro-arc oxide film layer within the transverse cracks and expansion, with the increase of loading frequency, membrane layer surface crack growth faster, but when the load frequency is 150 Hz, membrane layer and substrate separated most serious.