| With the diversification of the investment casting, the demands of the quantity and performance of ceramic core are improving increasingly. However, at present, the ceramic core can't satisfy the need of development because of the bad performance and production lag. Therefore, the key of the production of the investment casting is to enhance the performance of ceramic core. The ceramic core that was commonly used mainly contain silicon and aluminum. Silicon ceramic cores have the property of high-temperature activity, so the interface of the ceramic and metal had stick and sand porosity. Alumina cores are difficult to remove from the samples. Al2O3/SiO2 composite ceramic materials have many excellent performances, such as high temperature resistant, high-intensity and so on. The difficulties and shortcomings of alumina, silicon oxide and other ceramic core are overcome.In this paper, Al2O3/SiO2 composite ceramic cores with excellent performances are obtained by the extrusion molding processing. The amount of the raw materials, the sintering processing and the applications of the ceramic core are studied. The conclusions are as follows.1,The proper proportion of Al2O3/SiO2 ceramic core is mullite:kyannite:α-Al2O3: SiO2=14:4:2:1 by studying the raw material and chemical component.2,CMC is the favorable adhesive to prepare Al2O3/SiO2 ceramic core by contrasting and testing property of different adhesives in the study.3,The sintering system of the study is as follows: Heating up to 300℃from room temperature by 120 minutes, continuously sintering up to 600℃by 90 minutes and standing for 60 minutes, then sintering up to 1200℃by 90 minutes and standing for 60 minutes, finally sintering up to 1500℃by 90 minutes and standing for 30 minutes. When the sintering temperature is 1500℃, the proportion of water absorption reached 20.9%, the rate of porosity reached 36%, the volume density reached 1.96 g/cm3, the bending strength reached 28.2 MPa. 4,The results of the XRD patterns show that with the increasing of the sintering temperature, Al2O3 phase, SiO2 phase and kyanite phase were disappeared, and mullite phase existed at 1500℃. The results of the SEM images show that the porosity proportion of the sample was relatively small, and the cusp of the particle was blunt. The particles with more reasonable size were obtained.5,The results of researching the Al2O3/SiO2 ceramic core application show that casting prepared by ceramic core casting has precise dimension, smooth surface and well quality. Because the pores more than 30% can be eliminated directly by mechanism method, the process is simple and the cost is low. The annual output of ceramic core is up to three million by producing cosmically. |
