常压烧结与微波烧结ZTA陶瓷性能

选择Al2O3-ZrO2系统,采用微波烧结及常压烧结两种工艺,分别对ZTA陶瓷的力学性能和摩擦性能进行了测试比较,简单分析了影响ZIT陶瓷摩擦性能的主要因素,微波烧结使陶瓷的烧结温度降低,致密度提高,摩擦因数增大,磨损量减小。     

微波烧结 ZTA 陶瓷力学性能研究

选用微波烧结新工艺,对ＺＴＡ陶瓷力学性能进行了研究,获得了较传统烧结工艺优良的陶瓷力学强度和断裂韧性。同时,新工艺改善了陶瓷体的显微结构。     

烧结助剂对氧化铝陶瓷低温烧结的影响

氧化铝(Al_2O_3)陶瓷烧结温度较高,通过添加烧结助剂可以实现Al_2O_3陶瓷的低温烧结。对比分析了不同含量的CuO-TiO_2和MnO_2-TiO_2-MgO复合烧结助剂在不同的烧结温度下对Al_2O_3烧结性能的影响,得到了烧结助剂含量和烧结温度对Al_2O_3陶瓷体积收缩率、体积密度以及内部显微结构的影响规律。实验分析表明,在1 350℃的烧结温度下,添加4%(质量分数) CuO-TiO_2和MnO_2-TiO_2-MgO的烧结助剂,Al_2O_3陶瓷分别能获得高达3. 67 g/mm~3和3. 76 g/mm~3的体积密度,并且在扫描电子显微镜下观察到良好的显微结构。     

羟基磷灰石的微波烧结

对羟基磷灰石的微波烧结进行了系统研究,确定了制备致密HAP生物陶瓷材料的最佳微波烧结工艺条件.通过XRD、SEM等手段研究了烧结温度和时间对HAP生物陶瓷的物相和显微结构的影响,测试了烧结收缩率和抗折强度.结果表明,微波烧结利于HAP陶瓷坯体的致密化,可以实现低温快速烧结,并提高陶瓷的机械强度;微波烧结对HAP的分解有促进作用,而且随着烧结温度升高和时间延长HAP分解程度增大.1 200℃烧结30 min的HAP陶瓷样品抗折强度最高,为(95.42±3.45)MPa,其主晶相为HAP和β-TCP.     

圆柱形微波多模烧结腔烧结Al_2O_3陶瓷的性能

应用微波加热技术进行高纯Al2O3陶瓷烧结是一种理想的选择.本文使用一种新型的圆柱形微波多模烧结腔体进行了Al2O3陶瓷的烧结研究,该设备可在短时间内达到较高的烧结温度,并能实现坯体的整体烧结.分别对纯Al2O3粉体和Al2O3/MgO混合粉体进行了烧结实验,结果表明,添加MgO作为助烧剂烧结得到的陶瓷试样的相对密度高于纯Al2O3粉体烧结得到的陶瓷试样,在1 700℃下保温40 min,其相对密度可以达到理论密度的97.8%,维氏硬度达22.3 HV/GPa.从SEM图中可观察到试样微观结构良好,晶粒大小均匀,致密化程度高.     

陶瓷材料的微波烧结特性及应用

介绍了微波烧结陶瓷材料的应用历史、基本原理，分析了陶瓷材料的微波烧结特性和微波烧结在氧化物陶瓷、非氧化物陶瓷及透明陶瓷方面的应用，指出了应用中存在的一些待解决的问题，展望了微波烧结陶瓷材料的应用前景。     

羟基磷灰石的微波烧结

对羟基磷灰石的微波烧结进行了系统研究，确定了制备致密HAP生物陶瓷材料的最佳微波烧结工艺条件．通过XRD、SEM等手段研究了烧结温度和时间对HAP生物陶瓷的物相和显微结构的影响，测试了烧结收缩率和抗折强度．结果表明，微波烧结利于HAP陶瓷坯体的致密化，可以实现低温快速烧结，并提高陶瓷的机械强度；微波烧结对HAP的分解有促进作用，而且随着烧结温度升高和时间延长HAP分解程度增大．1200℃烧结30min的HAP陶瓷样品抗折强度最高，为（95．42±3．45）MPa，其主晶相为HAP和β-TCP．     

圆柱形微波多模烧结腔烧结Al2O3陶瓷的性能

应用微波加热技术进行高纯Al2O3陶瓷烧结是一种理想的选择.本文使用一种新型的圆柱形微波多模烧结腔体进行了Al2O3陶瓷的烧结研究,该设备可在短时间内达到较高的烧结温度,并能实现坯体的整体烧结.分别对纯Al2O3粉体和Al2O3/MgO混合粉体进行了烧结实验,结果表明,添加MgO作为助烧剂烧结得到的陶瓷试样的相对密度高于纯Al2O3粉体烧结得到的陶瓷试样,在1 700℃下保温40 min,其相对密度可以达到理论密度的97.8%,维氏硬度达22.3 HV/GPa.从SEM图中可观察到试样微观结构良好,晶粒大小均匀,致密化程度高.     

微波烧结ZTA陶瓷力学性能研究

选用微波烧结新工艺，对ＺＴＡ陶瓷力学性能进行了研究，获得了较传统烧结工艺优良的陶瓷力学强度和断裂韧性，同时，新工艺陶瓷体积显微结构。     

微波烧结BaTiO3陶瓷的微结构

本文报道了微波烧结ＢａＴｉＯ３陶瓷的初步研究结果。利用微波烧结的ＢａＴｉＯ３陶瓷、与常规烧结相比，其轴向收缩率显著地不同。采用ＳＥＭ观察其微观结构也与常规烧结有显著的差异。ＸＲＤ分析其结构为四方晶系，初步推断此现象与ＢａＴｉＯ３陶瓷在微波场中的取向生长有关。     

Microwave sintering of W-15Cu ultrafine composite powder prepared by spray drying &; calcining-continuous reduction technology

The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated.In comparison to the conventional H2 sintering processing,microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time.Furthermore,higher performances in microwave sintered compacts were obtained,but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.     

Properties, phases and microstructure of microwave sintered W-20Cu composites from spray pyrolysiscontinuous reduction processed powders

The effects of microwave sintering on the properties, phases and microstructure of W-20Cu alloy, using composite powder fabricated by spray pyrolysis-continuous reduction technology, were investigated. Compared with the conventional hot-press sintering, microwave sintering to W-20Cu composites could be achieved with lower sintering temperature and shorter sintering time. Furthermore, microwave sintered W-Cu composites with high densification, homogenous microstructure and excellent properties were obtained. Microwave sintering could also result in finer microstructures.     

Microstructure and strength modification of relaxor ferroelectric ceramics through microwave sintering for multilayer capacitors

Relaxor ferroelectric ceramics with the composition of xPb( Mg_(1/3) Nb_(2/3)O_3-yPb (Zn_(1/3)Nb_(2/3)O_3-zPbTiO_3 was fast sintered in a 2.45 GHz microwave system. Microwave-sintered samples illustrate more rapid densification and much smaller grain size microstructure than eonventional sintered samples. Also the microwave processing significantly increases the dielectric strength and flexural strength of the relaxor so that its strength becomes comparable with modified BaTiO_3, and could obtain comparable dielectric properties in comparison with conventional sintering process. Microwave processing has many advantages for sintering of relaxor ferroelectrie ceramics used as multilayer capacitors.     

Microstructure analysis of microwave sintered ferrous PM alloys

The properties and microstructure of microwave and conventional sintered Fe-2Cu-0.6C powder metallurgy (PM) alloys were investigated. The experimental results show that microwave sintered alloy has the better properties (sintered density 7.20 g/cm³, Rockwell hardness 75 HRB, tensile strength 413.90 MPa and elongation 6.0%), compared with the conventional sintered counterpart. Detailed analyses by using optical microscopy and scanning electron microscopy (SEM) reveal that microwave sintered sample has finer microstructure with small, rounded and uniformly distributed pores, and also demonstrate the presence of more flaky and granular pearlite in the microwave sintered body, both of which account for the property improvement. SEM images on the fracture morphology indicate that a mixed mode containing ductile and brittle fracture is presented in microwave sintered alloy, in contrast with the brittle fracture in conventional sintered counterpart. Funded by the National Science and Technology Development Program (No.2004-09ZD)     

微波场中铜粉烧结行为的初步研究

实验研究了铜粉在微波场中的烧结行为,并就微波场中烧结金属粉末压坯的机理进行了相关讨论。结果表明在微波场中铜粉压坯能被无氧化快速烧结;经微波烧结后铜粉压坯内外具有均匀的致密度。微波不仅通过涡电流作用烧结铜粉压坯,铜粉颗粒间产生的弧光效应也起着重要的作用。     

等离子活化烧结新技术及应用

介绍了自行研制的等离子体化烧结装置的结构、特征和工艺参数，采用等离子体活化烧结法烧结了纳米级Al2O3,ZrO2粉和市售Cu粉，与微波等离子体烧结法、微波烧结法以及传统方法进行了对比，总结了该工艺的优点。     

Kinetics mechanism of microwave sintering in ceramic materials

Based on the traditional sintering model incorporating the characteristic of microwave sintering, the ionic conductance diffusion mechanism in microwave sintering was studied. A flat-ball model was presented to describe the kinetics process in microwave sintering, and was applied to the sintering process of TZP and ZrO₂-Al₂O₃ ceramics. The results indicate that the shrinkage rate of materials in microwave sintering is proportional to t ^2/3 and r ^−4/3, respectively, where t is the sintering time and r is the particle radius. Whereas, the shrinkage rate of materials in conventional sintering is proportional to sintering time t ^2/5. Our model suggests that microwave sintering is faster than conventional sintering, which shows a good agreement with the experimental observation in sintering process of TZP and ZrO₂-Al₂O₃. Supported by the State Key Program of National Natural Science of China (Grant No. 50332010) and the National Key Technology Research and Development Program for Resource and Environment of China (Grant Nos. 2006BAB12B03, 2006BAB12B05)     

纳米氧化铝陶瓷制备的研究进展

综述制备纳米氧化铝粉的主要制备方法:溶胶-凝胶法、沉淀法、微乳液法和爆炸法,以及纳米氧化铝陶瓷的烧结新工艺:热压烧结、微波烧结和放电等离子烧结等,与传统烧结方法相比,使用这些烧结工艺制备的产品性能更优异.     

THE CHARACTERISTICS OF THE PRESSURELESS SINTERED Si_3N_4-MgO-Ce0_2 CERAMICS

An investigation of the pressureless sintering of Si3N4 with MgO-CeO2 revealed that MgO-CeO2 is a most effective sintering aid for silicon nitride. The amount of MgO-CeO2 and sintering conditions have a strong influence on the densification behaviour and mechanical properties of the sintered materials. The effect of the additive and sintering conditions are discussed. The silicon nitride pressureless sintered with MgO-CeO2 retained a relative density of 98. 5% and a bending strength of 950 MPa. The Si Mg-Ce-O-N system is of great value for application and theoretical study.     

放电等离子烧结具有优异综合性能的新型NdFeB永磁材料

采用放电等离子烧结技术和传统烧结技术制备了烧结NdFeB永磁体,并研究了2种磁体的磁性能、力学性能和化学稳定性.与传统烧结磁体相比,放电等离子烧结磁体具有与其相当的磁性能及更好的耐腐蚀和力学性能.显微组织结果表明,放电等离子烧结磁体主相Nd_2Fe_(14)B的晶粒细小、均匀.边界富钕相仅有少量位于主相Nd_2Fe_(14)B颗粒周围,大部分以颗粒形式分布在主相三角晶界处.这种独特的显微组织特征对于晶间腐蚀过程及脆性沿晶断裂过程具有明显的抑制作用.因此,放电等离子烧结磁体表现出优异的综合性能.