LIU Xiaoying, FAN Shangwu, XU Yongdong, ZHANG Litong, CHENG Laifei

(National Key Laboratory of Thermos tructure Compos ite Materials , Northwes tern Polytechnical Univers ity, Xi' an 710072)

Abstract: A uniform mixture of silicon powder (granularity≤0.044 mm) and polyvinyl alcohol solution (PVA, 5wt%) in response to a certain proportion has been prepared. After sieving, prilling and vibrating packing, the green body has been pressed. The effects of the amount of water and polyvinyl alcohol (PVA) on the moldability and the performance of green body were studied. when the amount of water is more than 1wt%, the packed density is low and inhomogeneous which makes the shape irregular for unequal pressing. When the amount of water is between 0.5~1wt%, the packed density is greater which makes the shape regular. The amount of water is determined to be 0.5~1wt%. When the amount of PVA increases from 5wt% to 15wt%, the strength of the green compacts also increases . When the amount of PVA increases from 15wt% to 25wt%, the strength of the green compacts decreases and hard aggregates remain in green bodies . When the amount of PVA  is 15wt%, the strength of the green compacts is maximal (about 1.62MPa), and no res idual hard aggregates are present in green bodies . The amount of PVA is determined to be 15wt%.

Keywords: amount of water, binder, green body, cold is ostatic pressing