Research On Additive Manufacturing Process And Performance Of Cordierite Ceramics Based On DLP Light Curing Technology

Because of its low thermal expansion coefficient,high melting point,and good mechanical properties,cordierite ceramics are widely used in the field of automotive exhaust purifiers.With the introduction of more stringent emission standards,higher requirements have been placed on the performance of cordierite ceramics.Because of the difficult-to-process nature of ceramic materials,it is increasingly difficult for ceramic parts made by traditional ceramic preparation methods to meet demand.In this study,cordierite ceramics are prepared using DLP 3D printing.Compared with traditional ceramic preparation methods,it has the advantages of high forming accuracy,short production cycle,and can manufacture any shapes.In this study,the preparation of photocurable cordierite ceramic slurry was preliminary studied.Three types of cordierite ceramic particles with different particle sizes were prepared by grinding the powder,and three kinds of photocurable cordierite ceramic slurry with solid content of 45vol% and powder particle sizes of 0.35μm,3μm,and 7.41μm were successfully prepared for this study.Tests have found that these three types of paste have low viscosity,large penetration depth,and low critical exposure value,and are suitable for DLP printing.In this study,by designing orthogonal experiments,the effects of three key factors,such as layer thickness,exposure time,and particle size,on the forming properties,surface morphology,and mechanical properties of ceramics after sintering were studied.The effects of these three influencing factors on the forming precision,volume shrinkage,porosity,elastic modulus,hardness,compressive strength,and micro-morphology of ceramic parts before and after sintering were mainly studied.The study found that the particle size of the powder has the greatest effect on ceramic parts.The smaller the particle size of the ceramic part,the higher the forming accuracy.The dimensional change rate in all three directions after printing is less than 0.5%.The larger the volume shrinkage after sintering,the highest can reach 60%.At the same time,the denser the specimen,the smaller the porosity can reach 0.81vol%.The mechanical properties are also better,with its elastic modulus up to 90 GPa and hardness up to6 GPa.It is found through testing that the compressive strength of ceramics is not only related to the particle size of the powder,but also related to the crack condition,which is the result of the joint action of the two.The cracks on the surface of ceramics also show different conditions with the change of the particle size of the powder.Some cracks will heal after sintering,but there are still many cracks.An optimal preparation process was analyzed by orthogonal experiments: the particle size of the powder was 3 μm,the thickness of the layer was 50 μm,and the exposure time was 3 s.Finally,using this parameter,a complete and intact cordierite honeycomb ceramic part was successfully prepared.Three basic test patterns were designed in this study: a single curing line for single-layer printing,small holes for single-layer printing,and thin-walled patterns for multi-layer printing.From the line to the hole to the surface,and from the single layer to the multi-layer,the cause of forming error and the printing of small size ceramic parts using DLP light curing technology under different slurry and different exposure conditions were systematically studied Trends in accuracy.The change trends of line width and cross-section height before and after sintering of a single solidification line,the change trends of pore diameter before and after small hole sintering,and the change trends of wall thickness before and after thin wall sintering are mainly studied.Studies have found that exposure time has the greatest impact on printing accuracy.When the exposure time is too small,the size of the paste cannot be cured or the cured size is significantly small.When the exposure time is too large,the size of the test part is significantly larger due to the influence of light scattering.The minimum line width and cross-section height of the thin line prepared in this paper are 69.4 μm and 37.9μm,the minimum pore diameter is 109.67 μm,and the thinnest wall thickness is 92.4 μm.The study also found that the projection performance of the optical machine and the inherent properties of the paste will also affect the printing accuracy.