淀粉对氧化铝基陶瓷型芯性能的影响

为了解决氧化铝基陶瓷型芯不易脱芯的难题，加入一定量的淀粉作为成孔剂。以白刚玉粉为基体材料、石蜡和蜂蜡为增塑剂、二氧化硅粉和氧化镁粉为矿化剂，采用热压注法制备氧化铝基陶瓷型芯；制备工艺参数如下：浆料温度为90℃、热压注压力为0.5 MPa、保压时间为25 s；研究不同淀粉加入量对氧化铝基陶瓷型芯性能的影响。结果表明：在烧结过程中，样品中淀粉的烧失，增大了氧化铝基陶瓷型芯内部的孔隙率；随着淀粉加入量的增加，氧化铝基陶瓷型芯的室温抗弯强度降低、显气孔率增大、溶失性增大、体积密度减小；经1560℃烧结2.5 h后，淀粉加入量为8%的氧化铝基陶瓷型芯综合性能最好，其室温抗弯强度为24.8 MPa、显气孔率为47.98%、溶失性为1.92 g/h、体积密度为1.88 g/cm3。

Effects of Starch on Properties of Alumina-based Ceramic Cores

In order to improve the poor leachability of alumina-based ceramic cores, different amount of starch was added to the speci-mens as pore former. Alumina-based ceramic cores were prepared by hot injection technology using corundum powder as base material, paraffin wax and beeswax as plasticizer, silica powder and magnesium oxide powder as mineralizing agent, wherein the parameters of the hot injection process were as follows:temperature of the slurry was 90℃, hot injection pressure was 0. 5 MPa and holding time was 25 s. The effects of starch content on the properties of alumina-based ceramic cores were studied and discussed. The results indicate that during sintering period, the loss of starch in the specimens makes porosity of the alumina-based ceramic cores increase. When starch content increases, the room-temperature flexural strength of the ceramic cores reduces and the apparent porosity increases; the volatile solvent increases and the bulk density decreases. After being sintered at 1560 ℃ for 2. 5 h, room-temperature flexural strength of the alumina-based ceramic cores with starch content of 8%(mass fraction) is 24. 8 MPa, apparent porosity is 47. 98% when the vol-atile solvent is 1. 92 g/h and bulk density is 1. 88 g /cm3 , the complex properties are optimal.