Preparation SiC Ceramics By SLS Combined With PIP Technology And Study On Mechanical Properties

Selective laser sintering(SLS)technology is one of the most promising technologies in the field of additive manufacturing,The technology has the advantages of wide range of material selection,simultaneous formation of multiple shapes,short preparation period,and preparation of complex structures.However,due to the use of a polymer such as an epoxy resin as a bonding agent in the process,the strength of the test piece after printing and degreasing is low,which limits the application range of the material.In this thesis,the density of the prepared Si C ceramics is increased by a combination of selective laser sintering and chemical precursor infiltration pyrolysis(PIP).The effects of resin content,particle size and pressure on the mechanical properties of the materials were studied.The microstructure and mechanical properties of the materials were studied by means of SEM,EDS and laser particle size analyzer.The machine actually measured the compression and bending properties of the material after densification,and studied its mechanical failure mechanism.By adjusting the content of the resin in the mixed powder,the samples with5%,10% and 15% resin were respectively printed with A-Si C for experimental analysis.The experimental results show that the compressive strength of the specimen increases with the increase of the resin content after the thermocuring.However,the specimens with the resin content of 5% have the strongest mechanical properties after the degreasing and PIP process.The flexural strength And compressive strength reached 91 MPa and 145 MPa respectively.With the increase of the resin content,the final strength of the specimen gradually decreased,the porosity remained unchanged that are 26%-27%.This paper select B-Si C powder with smaller particle size as the raw material,and prepare the sample with 5% resin content for comparative analysis with A-Si C under the same environmental conditions,studied the effect ofparticle size Si C powder on the printing and mechanical properties of test pieces.The results show that the porosity of the two kinds of Si C powders prepared are both 55%-57% after degreasing.However,after the completion of the PIP process,the porosity of the specimen prepared by B-Si C is higher by 30.1% and the mechanical properties are lower.The flexural strength and compressive strength are 80 MPa and 120 MPa respectively.After thermocuring,some samples were selected for CIP,and compared with those without CIP.The results show that the CIP process significantly reduces the porosity of the printed samples,and the mechanical properties of the CIP samples are better than the samples without CIP after the PIP,the flexural strength and compressive strength are 110 MPa and 160 MPa,porosity are 21%-22%.Through the above design and analysis,It was obtained that the 3D printed Si C ceramics have lower porosity and higher mechanical properties,which is important in promoting the development of Si C ceramic preparation technology in our country,the application of related products and the utilization efficiency of raw materials.