CAJ | 학술논문

通过热压烧结方式制备Si3N4陶瓷,采用阿基米德排水法、SEM和四点弯曲法分别对样品的致密度、第二相、微观结构和力学性能进行测试.在添加MgO-Lu2O3-Re2O3三元添加剂的S3N4陶瓷中,(Sm2O3,Er2O3)易促使Lu2O3在晶界处形成第二相Lu4Si2N2O7.在添加MgO-Lu2O3-Re2O3(La2O3,Gd2O3,Er2O3)的Si3N4陶瓷中,长柱状晶均匀分布在较小的基体晶粒中,并弱化晶界,样品的四点抗弯强度均在900MPa以上,断裂韧性高于9 MPa·m1/2.而在添加MgO-Lu2O3-Sm2O3的Si3N4样品中,由于局部出现晶粒异常长大现象,强度和韧性提高较小.另外,与传统二元MgO-Re2O3添加剂相比,MgO-Lu2O3-Re2O3三元添加剂随着Re3+离子半径的改变,对Si3N4陶瓷微观结构、力学性能不会产生规律性的影响.
통과열압소결방식제비Si3N4도자,채용아기미덕배수법、SEM화사점만곡법분별대양품적치밀도、제이상、미관결구화역학성능진행측시.재첨가MgO-Lu2O3-Re2O3삼원첨가제적S3N4도자중,(Sm2O3,Er2O3)역촉사Lu2O3재정계처형성제이상Lu4Si2N2O7.재첨가MgO-Lu2O3-Re2O3(La2O3,Gd2O3,Er2O3)적Si3N4도자중,장주상정균균분포재교소적기체정립중,병약화정계,양품적사점항만강도균재900MPa이상,단렬인성고우9 MPa·m1/2.이재첨가MgO-Lu2O3-Sm2O3적Si3N4양품중,유우국부출현정립이상장대현상,강도화인성제고교소.령외,여전통이원MgO-Re2O3첨가제상비,MgO-Lu2O3-Re2O3삼원첨가제수착Re3+리자반경적개변,대Si3N4도자미관결구、역학성능불회산생규률성적영향.
Si3N4 ceramics with high mechanical properties were prepared by an introduction of MgO-Lu2O3-Re2O3 (Re= La,Sm,Gd,Er) multiple additives. The effect of ternary additives on relative density,second phase,micro-structure and mechanical properties were studied. Results showed that the addition of MgO-Lu2O3-Re2O3 (Re= Sm,Er) into Si3N4 ceramics led to the formation of Lu4Si2N2O7. And the addition of MgO-Lu2O3-Re2O3 (Re= La,Gd,Er) into Si3N4 ceramics led to distinctly bimodal structure distributions,weak grain boundary,and then resulted in high flexure strength (above 900 Mpa) and high fracture toughness (above 9 MPa·m1/2). However,the introduction of MgO-Lu2O3-Sm2O3 led to some exaggerated grains growth,which resulted in low flexure strength and low fracture toughness.