Study On The Process Of Polystyrene/Carbon Fiber Reinforced Composites Based On Selective Laser Sintering

There are many advantages for PS(Polystyrene)parts manufactured by SLS(selective laser sintering),such as high molding precision and short molding period,etc.Therefore,it is widely used in rapid investment casting field.While,due to it's low intensity,it could hardly be used in sintering complex parts of large size,as well as prototype models or function parts of higher intensity requirements.This work aimed at improving the bending strength of PS sintered parts.Composites of CF(carbon fiber)reinforced PS were prepared,of which mechanism in SLS was analyzed.The scope of each process parameter and the optimization of these parameters were studied through prototyping experiments.Moreover,PS reinforced with CF treated with vapor-deposition method was presented.The experiments data shows that the bending strength of PS sintered parts was improved effectually,which has practical significance in broadening the applications of PS parts.First of all,one kind of CF powder was designated as the reinforcing agent matched with the requirements of SLS process.Composites of PS reinforced with 10wt.%CF were prepared with mechanical mixing method.The decomposition temperature of PS/CF composites was measured through TG(Thermo-gravimetric)experiments,and it's molding mechanism based on the SLS was analyzed in term of thermal process between the composites and the laser.On the other hand,the spreading performance of powders was analyzed according to the requirements of SLS process,which established a theoretical foundation of subsequent sintering experiments.Secondly,the scope of each technical parameter matched with PS/CF composites was acquired through a series of molding experiments.The rules of intensity variation,density change and the dimensional error under the interaction of main parameters(scanning speed and layer thickness)were summarized,the causes of which were analyzed as well.Furthermore,the main process parameters(scanning speed,preheating temperature and layer thickness)were selected to carry out orthogonal test.Both the optimum technological conditions and how important each parameter is to bending strength were determined,using variance components method by intensity as indicators.The formation strength of PS was improved effectively.At last,the internal morphology of the parts was observed by scanning electric microscope,the key to further improving the bending strength were acquired.Finally,in order to fortify the combination power of phase surface,the CF was treated with vapor deposition method.Composites of PS reinforced with vapor deposited CF were prepared.Then prototyping experiments were carried out to demonstrate whether it is work to reinforcement.At last,the influence on formation intensity owe to the content of reinforcing agent was analyzed by changing mixing ratios.The results show that the optimal ratio is composites of PS reinforced with 10wt.%vapor deposited CF,of which the bending strength is up to 9.94MPa,about 72.3 percent higher than that of PS.