After the powder is sintered by SLS,the strength of sintered parts will be add. When sintering, due to work of high-temperature,atomic movement intensified,so that more atom get into the contact surface and then bonding surface. With expansion of bonding surface and improvement of sintered parts strength,and formed sintered neck at the same time,it let the original grain interface to form a grain interface, the grain boundary to the internal movement of particles, leading to grain growth. With growth up of sintered neck,decrease of total pore space volume, the distance shorter between the particles, it's really beginning of sintered body 's densification.Its process divide into three unobvious step:
1) beginning step----The original contact point or contact surface between particles. During liquid sintering process, the increase in density of the sintered body is a symbol of sintering.Selective laser sintering of ceramic powder involves complex chemical metallurgy and physical metallurgy processes, the original powder properties and the laser process parameters to influence and determine the sintering densification process and the sintered microstructures, both of which complement each other. Based on the preparation of SLS-specific composite ceramic powder, the author chooses the appropriate laser process parameters to carry out sintering experiments, combined with the analysis of the microstructure of sintered samples to optimize the powder components; and explore the ceramic powder SLS densification mechanism, Proposed to control the process defects, improve the sintering method.
The influence of physical properties of powder materials on ceramic quality
The physical properties of the powder material include particle size, particle morphology, particle size distribution, melting point, specific heat . These properties of the powder material are such that the formability of the sintered parts is the ease with which the powder material is suitable for selective laser sintering and the ability to obtain qualified prototypes or functional parts has a significant impact, not well handled, not only will affect the quality of molding, and even lead to the entire process can not be carried out.