Papers by Keyword: Centrifugal Slip Casting

Abstract: In this paper, centrifugal slip casting method was use to prepare carbon fiber/HA composites using the nanoHA particles and carbon fibers as initial materials. The morphology of the carbon fiber after modification of p-aminobenzoic acid was observed. The rheological characteristic of the carbon fibers/HA slurries was studied. The effects of the centrifugal acceleration on green density uniformity of carbon fiber/HA composites were analyzed. The bending strength and fracture toughness of carbon fiber/HA composites were measured. The results show the roughness of carbon fibers treated by p-aminobenzoic acid increases. At the pH of 10 and 5 wt% dispersant, the HA slurries with 3 vol% carbon fibers have good fluidity. After centrifuged at 2860 G for 30 min, the green compacts of HA composites have high and uniform the green density. After sintered at 1100°C for 1h, compared with carbon fiber/HA composites prepared by dry pressing, the modified carbon fiber/HA composites prepared by centrifugal slip casting have higher bending strength and fracture toughness of 89.4 MPa and 1.92MPa^1/2, respectively.

Abstract: Gradient Zirconia toughened alumina (ZTA) ceramics with high fracture strength and toughness were prepared using centrifugal slip casting method. Aqueous Al2O3-20vol% ZrO2 slurries with different solid contents were prepared and the rheological characteristic of the slurries were investigated. The effect of solid loading of slurries on green density difference of ZTA ceramic compacts was observed. Mass segregation of Al2O3 and ZrO2 particles were studied. Microstructure and bending property of the sintered ZTA ceramics were investigated. The results show that the segregation phenomenon of Al2O3-ZrO2 slurries comes form the difference of settling velocity of Al2O3 and ZrO2 particles. With the increase of solid content of slurries, the gradient distribution of green density becomes unconspicuous. After sintered at 1550○C for 2 h, the gradient ZTA ceramics centrifuged with 20vol% slurries have high sintered density (99.2% TD) and continuous gradient distribution of Al2O3 and ZrO2 particles. The fracture strength and toughness of gradient ZTA ceramic are 732MPa and 5.4MPam1/2, respectively.

Abstract: BP neural network model was developed for prediction of the flexural properties of Al2O3 ceramic prepared by centrifugal slip casting. In this paper, the model can well reflect the relationship between the process parameters including solid content of Al2O3 ceramic slurries (w), centrifugal acceleration (v), sintering temperature (T) and flexural properties of sintered products including fracture strength ( ) and fracture toughness (KIC). According to the registered BP model, the effects of w, v and T on and KIC were analyzed. The predicted results agree with the actual data within reasonable experimental error, which shows that the BP model is a practically very useful tool in the flexural properties prediction of the Al2O3 ceramic prepared by centrifugal slip casting. The system reduces the time required for planning and optimizing of centrifugal process parameters.

Abstract: Open-cell Al O ceramic foams with uniform cell structures and dense cell struts were fabricated by centrifugal slip casting using the plant seeds as the templates. The rheological characteristic of Al O slurries with up to 50 vol.% solid content was investigated. The shrinkage matching between the Al O green compact and the plant seeds during drying was studied. The effect of solid contents of slurries on change of green density of cell struts along the height of compacts was analyzed. The drying and sintering schedule of Al O green cakes were studied. The results indicated mass segregation of Al O particles with different sizes during centrifugal process was negligible for slurries with high solid loadings with 50 vol. %. The cell struts of green bodies had high density of 63.8% TD. After sintered at 1500 °C for 2 h, the final products had dense cell struts with high sintered density of 98.9%TD and homogeneous microstructure. The porosity and compressive strength of sintered products was 66.5% and 5.26 MPa, respectively.

Abstract: Centrifugal casting method was used to fabricate composites with graded structures in alumina-zirconia system. The composition profiles of the graded composites showed three distinct regions, with a greater part of the specimen showing nearly linear variation of compositions. The composition profile can be varied by using zirconia powder of different size ranges. The top of the specimens showed nano-scaled microstructures. The composition profiles can also be varied by altering zirconia content in the starting suspension. It was found that the composites with graded structures showed higher bending strength than that of uniform composites. On the other hand, the specimens fractured with the lower zirconia content region being the crack initiate plane showed higher bending strength than that of fractured form higher zirconia content region.