Research On Selective Laser Sintering Of Al₂O₃ Powder Under The Condition Of No Binder

With the advent of economic globalization, selective laser sintering as an advanced rapid manufacture technology has gained extensive application in many fields due to its unique advantages and broad application prospect. However, the technology still exists many difficulties, especially for hard and brittle ceramic materials processing. Problems, such as splash, gasification, spheroidizing, overheating, warping deformation and volume contraction etc., occurred in the laser sintering process need to be resolved. For solving these problems, this thesis designed an automatic pave powder experiment device and studied the influence of laser sintering process parameters on the sintering sample quality, C/Al2O3 composite powder melting-solidification mechanism, microstructure and post-treatment microstructure of the sintering samples, and also the mechanism of laser sintering. The main research results obtained in this thesis are listed as follows:A pave powder experiment device was designed based on the existing laser marking machine, and a program for PC and lower level computer was written using Visual Basic, thus a selective laser sintering system was established. Through the revision and the debugging during the process, the pave powder thickness can reach 0.1 mm, and could meet the need of experimental accuracy.This experiment use orthogonal design to arrange experiments and optimize sintering process parameters in selective laser sintering process. The research was focused on the influence of various process parameters on the sintering sample quality. The optimum process parameters are:the laser power was 17.5 A, the scanning speed was 350 mm/s and the scanning interval was 60μm. The experiment results show that the primary relation of the different factors is the laser power> the scanning speed> the scanning interval. Laser sintering temperature and sintering time are the main aspects of the quality of the sintered samples. So if we take the two factors into consideration, we can improve the samples sintered quality.Through analyzing of the microstructure of the sample, we revealed the laser and C for powder particles of sintering effect mechanism, and found in sintering process of powder particles existing in the warpage and holes splash gasification phenomena, seriously affect the quality of sinter samples. Thus we must adopt post-processing technology, which can reduce the holes in the area, improve mechanical strength and promote the structural integrity of the sample.In conclusion, the selective laser sintering of C/Al2O3 composite powder research achievements for selective laser sintering system provides a reference for the further improvement. In order to expand the application fields of the rapid prototyping technology, realize ceramic and other hard brittle materials forming laid a theoretical foundation and technology practice guidance.