Experimental Study On Laser Engineered Net Shaping Of TC4/ZrO₂ Graded Materials

TC4 titanium alloy has the advantages of high strength,high yield ratio and good corrosion resistance.It is widely used in aerospace,nuclear and chemical industry,power industry,marine engineering and other fields.However,it also has disadvantages such as poor wear resistance,low surface hardness,and poor resistance to high temperature oxidation.ZrO₂ ceramics with good wear resistance,high temperature performance,high thermal expansion coefficient has the excellent performances to be coating materials.Due to differences in thermal properties,direct bonding of TC4 and ZrO₂ inevitably has a greater bonding stresses,which is likely to cause cracking of the ceramic.The graded bonding of TC4 and ZrO₂ is helpful to alleviate the bonding stress caused by direct bonding.And the metal-ceramic functionally graded material has both the advantages of good toughness of metal materials and high hardness of ceramic materials,which can effectively guarantee the long-term reliable operation of the component in the complex environmentIn order to obtain metal and ceramics graded materials with good bonding properties,the TC4/ZrO₂ functionally graded materials with good surface quality and good performance were formed by laser engineered net shaping using optimized process parameters for different material composition proportion.The process parameters,microstructure and mechanical properties of samples were explored.The microstructure,element transition and mechanical properties of TC4/ZrO₂ functionally graded materials were investigated by means of optical microscope,scanning electron microscope,energy dispersive spectrometer,microhardness tester and friction and wear tester.The mechanism of microstructure evolution of different constituent materials was and its effect on graded bonding and mechanical properties was revealed.Specific research contents are as follows.?1?Three different scanning paths are planned to study the effect of path planning on surface quality and macro morphology when forming square samples.The optimized parameters of the forming samples under different TC4/ZrO₂ proportion were investigated.The hot crack of the sample is suppressed by lowering the scanning speed to obtain different proportions of samples with good surface quality and macro morphology.?2?The XRD phase analysis,optical microscopy,SEM analysis and EDS element analysis of TC4/ZrO₂ composites with different composition proportions were carried out.The changes of grain morphology and element distribution were summarized and analyzed to study the effect rule of characteristic of microstructure on graded bonding and performance of composition.?3?The functionally graded square and direct bonding square were formed,and the change rule of the microstructure and element transition form of component transition zone of two different components along graded direction were analyzed and compared.The effect of graded bonding on alleviating the bonding stress was revealed.Microhardness and wear properties of materials were analyzed combining the microstructure characteristics.Optimized process was used to form the space rail friction pair.The advantages and problems of forming structural component by laser near net shaping was studied.