Study On Preparation And Properties Of Ti-Si-C Composite By Laser Selective Melting

Ceramic-metal composites have been extensively studied and applied because of their good comprehensive properties.However,traditional forming methods of composite material are difficult to meet the application needs.Selective Laser Melting(SLM)is a kind of additive manufacturing technology,which is conducive to the realization of material structure design.This study is based on the Ti/SiC reaction system,using the SLM method to directly form Ti-Si-C composite material,and explores the material forming mechanism.Effects of laser parameters,laser remelting process and structure design method on the phase composition,microstructure and mechanical property of the formed material are also studied.The main research results are as follows:(1)The decomposition of SiC and a series of chemical reactions occurred during the SLM forming process.Due to the difference in crystallization temperature between the phases and the shrinkage of the melt,redistribution of the elements occurs.After process optimization,the compressive strength of the sample formed by SLM using 175 W laser power,1000 mm/s laser scanning speed,0.03 mm layer thickness,0.07 mm hatch spacing reached 88.25 MPa,the size error was 4.94%,and the open porosity rate was 6.75%.(2)The laser remelting process has a significant effect on the surface morphology and mechanical property of the samples.Compared with unremelted sample in control group,the size error of sample remelted using 75 W laser power,1000 mm/s scanning speed is reduced by 27.49%,and its open porosity rate is reduced by 1.85%.The compressive strength of sample using 175 W laser power,1000 mm/s scanning speed can be increased by 254.95%.(3)A multi-parameter SLM process was used to prepare co-continuous Ti-Si-C composite material with triply periodic minimal surface.Compared with sample with no structure design,the compressive strength of the co-continuous composite sample is 111.10 MPa,which is increased by 29.05%,the size error is 3.68% and the open porosity rate is10.90%.At the same time,the compressive strength stability of the structure sample is improved.The above conclusions show that the structure and mechanical property of Ti-Si-C composites formed by SLM can be adjusted by means of structure design,etc.This study provides a reference for the integration of component-structure-process design to achieve high-performance composite material preparation.