THE ROLE OF MgO-CeO_2 IN THE DENSIFICATION OF Si_3N_4

An investigation of the pressureless sintering of Si3N4 with MgO-CeO2 reveals that MgO-CeO2 is a much more effective sintering aid for silicon nitride than either MgO or CeO2. The amount of MgO-CeO2 and MgO/CeO, weight ratio has a strong influence on the densification be-haviour and mechanical properties of the sintered materials. The silicon nitride pressureless sintered with MgO-CeO2 re-tains a relative density of 98. 5% , a bending strength of 950 MPa. The Si-Mg-Ce-O-N system is of great value for appli-cation and theoretical study.

Studies on Graft Copolymerization of Acrylic Acid onto Ramie Fibers with Chromic Acid Initiation System

The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).

MLCC的应变测试的应用与案例分析

StrainGageTest（应变测试）相对于电子制造业来说，是一个比较新的一个概念。应变测试可以量化零件所在位置的应变，而根据这个量化的应变来判断零件破裂的风险，从而为改善措施提供方向。本文通过对实际制程进行应变测试，总结出某些制程中减少MLCC破裂的方法，以提高产品的可靠性。本文中的应变测试，如无特殊说明，都是基于1．6mm的FR一4PCB进行的。