共查询到19条相似文献,搜索用时 156 毫秒
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以传统氧化物法合成的Mn-Zn铁氧体前驱体和外购前驱体为实验原料,经压制成形后用频率为2.45 GHz的微波在1 200~1 400℃烧结制备Mn-Zn铁氧体软磁材料.对烧结过程样品的微观结构和形貌进行了研究,并探究了烧结过程致密化特性及微波加热温度对Mn-Zn铁氧体密度的影响.研究表明:微波烧结的Mn-Zn铁氧体具有典型的尖晶石结构,样品主体相为Mn0.4Zn0.6Fe2O4;用SEM观察样品形貌,发现在1 350~1 400℃烧结的样品结晶状况良好,晶界平直,烧结组织均匀;微波烧结温度对密度有较大影响,在1 200~1 400℃,随着烧结温度升高样品密度增高,密度为4.80~5.28 g/cm3,在1 400℃烧结样品比较致密.微波烧结可以实现样品的快速致密. 相似文献
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Mn洳功率铁氧体磁芯制造生产过程产生的开裂有多种形式存在,生产过程的变化产生了不同的开裂,并且前后关联影响。通过对粉料物理参数、模具设计、和烧结曲线以及装烧方式上进行调整,解决MnZn功率铁氧体磁芯不同的开裂现象。 相似文献
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以共沉淀-喷雾干燥法制备的Ce0.8 Sm0.2 O1.9(SDC)粉体为原料,模压成型后高温烧结获得SDC电解质陶瓷片.研究模压成型过程中加压时间、压力大小以及烧结温度对烧结体致密度的影响,利用XRD和SEM分别对不同烧结温度获得的烧结体结构和表面形貌进行分析.研究表明,压力30MPa、加压时间30min后获得的坯体,随着烧结温度的升高,烧结体致密度呈上升趋势,烧结温度达到1450℃时进入烧结后期,烧结体具有较高的致密度.此外,通过测定烧结过程中坯体收缩率,对SDC电解质陶瓷片的烧结动力学进行了研究,从而确定SDC电解质致密化的烧结温度为1300~1500℃. 相似文献
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草酸-硝酸盐低热固相反应法制备(Ni_(0.58)Cu_(0.2)Zn_(0.22))Fe_(1.96)O_4铁氧体 总被引:1,自引:0,他引:1
以草酸和金属硝酸盐为原料,用低热固相反应法合成了纳米(Ni0.58Cu0.2Zn0.22)Fe1.96O4尖晶石型铁氧体,借助FT-IR、DSC-TG、XRD、TEM以及SEM等技术对固相反应过程和样品进行了研究及表征.FT-IR研究表明,草酸和金属硝酸盐在研磨过程中发生低热固相反应,生成金属草酸盐前驱体;FT-IR和XRD分析表明,前驱体经不同温度焙烧后得到单一尖晶石相的NiCuZn铁氧体粉末;依据TEM和SEM表征证明,前驱体在450℃分解1h后铁氧体粒径约为30~40nm,铁氧体于900℃烧结为陶瓷体后,晶粒约为2~4μml,烧结致密,磁谱测量表明,900℃烧结样品的磁导率为210,截止频率为28MHz. 相似文献
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采用断口观察、金相检验、化学成分分析、硬度检验等方法对Cr12MoV钢模具在线切割过程中产生开裂的原因进行了分析。结果表明:热处理工艺不当引起模具内的残余应力较大,加上线切割时导致模具内的残余应力重新分布,使模具在线切割时局部边缘产生超过材料抗拉强度的拉应力是导致模具开裂的主要原因;另材料显微组织中的共晶碳化物最大尺寸严重超标,是导致该模具线切割时开裂的另一原因。 相似文献
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某重型汽车的一桥摆臂在服役期间发生开裂。通过宏观检查、化学成分分析、微观分析、金相检验等方法,对摆臂的开裂原因进行了分析。结果表明:该开裂摆臂的开裂模式为疲劳开裂,摆臂在锻造过程中产生了折叠缺陷,折叠缺陷内伴生夹杂及微裂纹,在工作应力下折叠缺陷成为疲劳源,最终导致摆臂开裂。 相似文献
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Effect of Sintering Temperature and Zinc Content on Some Properties of Li-Zn Ferrites 总被引:1,自引:0,他引:1
A.M.El-Saird S.B.Hanna 《材料科学技术学报》1996,12(5):329-334
Li-Zn mixed ferrites with composition formula ZnxLi0.5-x/2Fe2.5-x/2O4 (0.2≤x≤0.8) were prepared by the usual ceramic method in 1000~1150℃. The effects of Zn substitution and sintering temperature on the formation, densification, microstructure and a.c. electrical conductivity have been studied. Under the effect of changing the firing temperature and Zn content, high sintered Li-Zn ferrite bodies are achieved. More fine structure bodies having high electrical resistance are obtained at high Zn content 相似文献
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S. -A. Cho 《Journal of Materials Science》1974,9(12):1949-1954
A study was made to determine the effects of a double-soak sintering process on the saturation magnetization, Curie temperature and hysteresis properties of an Al-substituted MgMn-microwave ferrite. This process decreases saturation magnetization and magnetic induction, while increasing the loop squareness and the Curie temperature. The double-soak sintering process improves the properties of the ferrite for application in a low-microwave-frequency band (i.e. S-band) latching phase shifter. This improvement could not be achieved by increasing the Al3+ content, as this tends to reduce the Curie temperature, and thus decreases the thermal stability. The double-soak sintering process, however, enables a composition to be used which initially has a slightly higher saturation magnetization than the desired value. 相似文献
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孙银林 《理化检验(物理分册)》2012,(10):697-700,703
对CB30铸造铁素体不锈钢连接圈内浇口产生裂纹的原因进行了分析。结果表明:该零件显微组织中存在马氏体脆性相是导致其脆性开裂的根本原因;通过改进连接圈内浇口结构以及浇铸后铸件的脱壳方式,并延长铸件的退火热处理保温时间,可以有效地避免环形类CB30铁素体不锈钢铸件的脆性开裂。 相似文献
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为了研究45钢制曲柄发生断裂以及组织中异常铁素体产生的原因,并提出改进措施,采用化学成分分析、断口扫描、金相检验、硬度测试等方法进行测试分析.结果表明,曲柄在锻造后调质前,由于工艺不当使组织中出现大量条状、针状和网状的铁素体,且一直保留到调质后,使曲柄的力学性能低于技术要求,最终导致曲柄断裂. 相似文献
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活性炭负载Co0.8Zn0.2Fe2O4铁氧体的制备及电磁性能研究 总被引:1,自引:0,他引:1
采用溶胶-凝胶法制备活性炭负载纳米钴锌铁氧体复合吸波材料研究。以柠檬酸为络合剂制备Co0.8Zn0.2Fe2O4铁氧体溶胶,加入活性炭于溶胶中,经浓缩制得活性炭/钴锌铁氧体凝胶,再经过低温煅烧,制备出形态和结构理想的活性炭负载钴锌铁氧体复合材料;详细地考察烧结温度、煅烧时间及活性炭与铁氧体的配比等工艺参数对复合材料的形态和结构的影响;分别采用X射线衍射(XRD)、扫描电镜(SEM)和能量散射X射线荧光光谱(EDX)对制备出的复合材料进行形貌、结构及组成表征分析。采用波导法在8.2~12.4GHz波段对活性炭负载纳米钴锌铁氧体复合材料进行电磁参数测试分析,结果表明所制备活性炭负载纳米钴锌铁氧体复合材料具有较高的电、磁损耗角正切值,其吸波性能较好。 相似文献
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The co-firing characteristics of ZnO varistor and NiZn ferrite thick films were investigated, the objective being to create an integrated passive device. Bismuth oxide additions were used to increase the shrinkage of the ferrite during sintering. Dilatometry analysis proved that well-matched shrinkage characteristics could be obtained for bismuth oxide-modified ferrite compositions and the starting varistor material. Cross-boundary diffusion across the co-fired varistor-ferrite interface occurred during sintering, but application of a barrier layer of pure zinc oxide reduced this phenomenon considerably. By tailoring the shrinkage, strong, crack-free co-fired layers with no evidence of cracking or delamination were obtained. No deleterious effects were observed due to electroding of the varistor and ferrite materials. 相似文献
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The effect of anisotropy field and saturation induction on phase shift at millimeter-wave frequencies has been examined for hexagonal ferrite materials. The analysis was done for both uniaxial and planar anisotropy at three particular frequencies of technological interest, 30, 60, and 90 GHz. The work was concerned primarily with materials; a simple thin slab device configuration was used for the analysis. Limitations on materials parameters due to propagation cutoff, phase error degradation over a specified bandwidth, and low field loss were also considered. The results indicate that any improvement in phase shift over conventional cubic ferrites will require a high saturation magnetization, comparable to that of Li-Zn ferrite, and moderate (6-10-kOe) to large (20-30-kOe) anisotropy fields, depending on the frequency.<> 相似文献
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Manganous-zinc ferrites are best prepared directly from MnO and can be conveniently pressed with non-volatilizable binders
such as polyvinyl alcohol which however can be burnt out without oxidizing the Mn2+ in the ferrite by sintering in a static atmosphere generated by the thermal dissociation of active ferric oxide pellets placed
out of contact with the ferrite in the closed sintering unit. Such a process eliminates cracks and rejections in the sintered
pieces besides giving very satisfactory and reproducible results.
NCL Communication No. 3059 相似文献
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为解决元宝梁冲压开裂问题,用OM和SEM等仪器与ABAQUS有限元仿真软件对600 MPa级元宝梁用钢冲压开裂原因进行了分析.结果表明:600 MPa级元宝梁用钢化学成分、力学性能与冷弯性能均满足标准要求,金相组织为准多边形铁素体与少量珠光体的混合组织,不存在带状组织;开裂件断口形貌呈现出明显鱼骨状形貌,钢板中心分层,两侧分布起源于中心分层并沿同一方向扩展的三角形台阶状断口,不同形貌断口均属于韧性断裂,而断口整体形貌显示材料在断裂前没有发生缩颈过程.利用ABAQUS软件对"先冲压再压边工艺"与"先压边再冲压工艺"两种工况进行有限元分析,结果显示:先冲压再压边工艺边部应力集中更严重,边部节点应力超过了材料抗拉强度从而导致撕裂现象的发生;由"先冲压再压边工艺"改为"先压边再冲压工艺"后元宝梁冲压开裂率由50%降至0,材料边部变形均匀,未见缩颈与开裂现象发生. 相似文献