表面活性剂对Mg_(2)TiO_(4)微波陶瓷注射成形喂料流变性能的影响

Effect of surface modifier on the rheological properties of Mg_(2)TiO_(4) microwave ceramics injection molding feedstock

分别添加硬脂酸(SA)、油酸(OA)、γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)和γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)等4种表面活性剂对Mg_(2)TiO_(4)粉末进行改性,通过红外分析和粒度测试,研究表面活性剂对Mg_(2)TiO_(4)粉末粒径分布的影响和作用机理。并用改性前后的Mg_(2)TiO_(4)粉末制备装载量(体积分数)为44%的注射成形喂料,通过表征粉末喂料的黏度、最大装载量φ;、流变激活能和屈服应力来研究不同改性剂对喂料流变性能的影响。结果表明:表面活性剂通过化学吸附与Mg_(2)TiO_(4)粉末相接,可有效减少粉末团聚。用OA对Mg_(2)TiO_(4)粉末进行改性可使喂料黏度从39.55 Pa·s显著下降到5.43 Pa·s(剪切速率为100 s^(-1)),激活能从62 kJ/mol下降到38k J/mol,并且在170℃得到最低的屈服应力12 Pa (改性前为1 832 kPa)。用KH560改性的喂料φ;最大,为135%。

Mg_(2)TiO_(4)powders were modified by surfactants of stearic acid(SA), oleic acid(OA), 3-glycidyloxy-propyltrimethoxysilane(KH560) and 3-methacrylate-propyltrimethoxysilane(KH570). The effects of surfactants on the particle size distribution of Mg_(2)TiO_(4)powders and its mechanism were characterized by infrared analysis and particle size measurement. The Mg_(2)TiO_(4)powders before and after modification were used to prepared feedstocks with 44% solid load(volunm fraction). The effects of surfactants on the rheological properties, theoretical maximum loading capacity φ;,activation energy and yield stress of feedstock were studied. The results show that the surfactants are chemisorbed on Mg_(2)TiO_(4)powder, which effectively reduce powder agglomeration. The OA can significantly reduce the viscosity and rheological activation energy of feedstock. The viscosity decreases from 39.55 Pa·s to 5.43 Pa·s(100 s;);the activation energy decreases from 62 kJ/mol to 38 kJ/mol(100 s^(-1)). The lowest yield stress of 12 Pa is obtained at 170 ℃(1 832 k Pa before modification). The maximum solid loading modified with KH560 is 135%.