Powder-binder separation in injection moulded green parts
Powder-binder separation in injection moulded green parts
复制标题
DOI：
10.1016/j.jeurceramsoc.2010.02.020
复制
发表时间：
2010-10-01
影响因子：
5.7
通讯作者：
Moritz, Tassilo
中科院分区：
文献类型：
--
作者：
Mannschatz, Anne;Hoehn, Soeren;Moritz, Tassilo
对于粉末注射成型（PIM），陶瓷粉末与热塑性粘合剂系统混合以获得可注射原料。与聚合物部件的注塑成型相反，在成型步骤之后，在将陶瓷部件烧结至全密度之前，必须去除粘合剂。在模具填充过程中，剪切力作用在混合物上，可能导致粉末颗粒和粘合剂分离。在这种情况下，在模具表面和内部界面处形成聚合物膜，这在脱粘部件中引起微观结构缺陷。特别是对于多组分部件，这种影响至关重要，因为连接区域的粘结剂薄膜会削弱两个组分之间的粘结强度，甚至可能导致分层。为了检测注射成型的散装材料和双组分部件连接区域的粘结剂分离，研究了绿色样品的微观结构。由于传统的机械加工技术如研磨和抛光会改变原始结构，例如当颗粒从基体中拉出时，粘合剂会涂抹到表面上，因此采用特殊的陶瓷工艺制备横截面。这种方法基于宽离子束技术，能够同时抛光硬陶瓷颗粒和软聚合物分子，而不会破坏结构或在表面产生浮雕。在分析的样品中，发现粘合剂聚集沿着流线、焊缝、所谓死水区的边界和双组分部件的界面。(C)2010爱思唯尔有限公司版权所有。
For powder injection moulding (PIM) the ceramic powder is mixed with a thermoplastic binder system to achieve an injectable feedstock. In contrast to injection moulding of polymeric components, the binder must be removed after the shaping step before sintering the ceramic part to full density. During the mould filling process shear forces act on the blend that might cause separations of powder particles and binder. In this case polymer films form at the mould surface and at internal interfaces which induce microstructural defects in the debinded part. In particular for multi-component parts this effect is critical since binder films in the joining zone weaken the bonding strength between the two components that might even lead to delamination.For detecting binder separations within the injection moulded bulk material and at joining zones of two-component parts the microstructure of green samples has been studied. Since conventional machining techniques like grinding and polishing modify the original structure, e.g. when particles are pulled out of the matrix and binder smears onto the surface, a special ceramographic method for the preparation of cross-sections was applied. This approach bases on broad ion beam techniques and enables the simultaneous polishing of hard ceramic particles and soft polymer molecules without destroying the structure or producing a relief at the surface. In the analysed samples binder accumulations were found along flow lines, at weld lines, at boundaries of so-called dead water regions and at the interface of two-component parts. (C) 2010 Elsevier Ltd. All rights reserved.