共查询到20条相似文献,搜索用时 78 毫秒
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采用流延法制备了Si3N4块体及Si3N4/BN层状材料。流延法已经在陶瓷的制备工艺中得到了广泛的应用,但是很少用于Si3N4体系,尤其是水基流延法。用流延法制备Si3N4/BN层状材料时,可以较为容易的控制坯片的厚度,得到性能稳定的层状材料。 相似文献
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采用磁控溅射的方法制备了Si3N4/FePd/Si3N4三层膜, 研究了非磁性材料Si3N4作为插入层对磁记录FePd薄膜结构与磁性能的影响。结果表明, 热处理后Si3N4分布在FePd纳米颗粒之间, 抑制了FePd晶粒的生长, 与纯FePd薄膜相比, Si3N4/FePd/Si3N4薄膜的颗粒明显得到细化; 通过添加Si3N4层, FePd薄膜的晶体学参数c/a从0.960减小到0.946, 表明Si3N4可以有效促进FePd薄膜的有序化进程, 同时提升了矫顽力和剩磁比, 分别提高到249 kA/m、0.86; 随着600℃退火时间的进一步延长, 添加Si3N4的薄膜磁性没有迅速下降, 在较宽的热处理时间范围内磁性能保持在比较高的水平, 提高了抗热影响的能力。Si3N4作为插入层对FePd薄膜的磁性能具有较大的提升作用, 这对磁记录薄膜的发展具有重要意义。 相似文献
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通过添加TiN改善Si3N4陶瓷的加工性,结果表明,添加TiN含量达30wt%,可实现电火花切割加工。 相似文献
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Si3N4/SiC纳米复合陶瓷的微观结构 总被引:5,自引:0,他引:5
利用JEM2000EXⅡ高分辨电镜和HF2000冷场发射枪透射电镜对Si3N4SiC纳米笔合陶瓷材料的微观组织,结构和成分进行了研究。结果表明,SiC颗粒弥散分布基体相β-Si3N4晶内和晶界,晶内SiC颗粒与基体相的界面结构有三种类型;1)直接结合的的界面;2)完全非晶态的界面;3)混合型的界面,晶间SiC颗粒与基体相的界面大部分是直接结合的。 相似文献
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以国产Si粉和Si3N4粉为原料,添加适量的Y2O3和Al2O3烧结助剂,经凝胶注模成型后,在流动的高纯氮气氛中,采用反应烧结工艺制备出结构均匀、性能良好的Si3N4透波陶瓷,并深入研究了组分配方和烧结工艺对硅粉氮化率及材料的力学性能与介电性能的影响.研究结果表明:提高烧结温度能明显改善硅粉的氮化程度,当烧结温度超过1450℃、保温4h以上时,硅粉可完全氮化;起始原料中Si3N4含量为65%时,样品的介电性能最好,其介电常数为4.8,损耗角正切值为0.78×10-2;起始原料中Si3N4含量为35%时,样品的力学性能最好,其抗弯强度为129.5MPa. 相似文献
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TiN/Si3N4纳米多层膜的生长结构与超硬效应 总被引:3,自引:1,他引:3
采用磁控溅射方法制备了一系列不同Si3N4和TiN层厚的TiN/Si3N4纳米多层膜,采用X射线衍射、高分辨电子显微分析和微力学探针表征了薄膜的微结构和力学性能,研究了Si3N4和TiN层厚对多层膜生长结构和力学性能的影响.结果表明:当Si3N4层厚小于0.7 nm时,原为非晶的Si3N4在TiN的模板作用下晶化并与之形成共格外延生长的柱状晶,使TiN/Si3N4多层膜产生硬度和弹性模量异常升高的超硬效应.最高硬度和弹性模量分别为34.0 GPa和353.5 GPa.当其厚度大于1.3 nm时,Si3N4呈现非晶态,阻断了TiN的外延生长,多层膜的力学性能明显降低.此外,TiN层厚的增加也会对TiN/Si3N4多层膜的生长结构和力学性能造成影响,随着TiN层厚的增加,多层膜的硬度和弹性模量缓慢下降. 相似文献
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This study examined hardfaced cladding of S42000 stainless steel powder with added silicon nitride Si3N4 on a medium carbon steel using a 1200-W CO2 laser. Experimental results indicated that a well-proportioned cladding layer was obtained with an overlap of 50% at a traverse speed of 5 mm/s and a powder feed rate of 2 g/min. The degree of dilution, depth/width (D/W) ratio and microhardness of the cladding layer was increased by adding up to 5 wt.% silicon nitride. Retained austenite and wear decreased with increasing amounts of silicon nitride addition. The silicon nitride decomposed in the cladding layer during the laser treatment. 相似文献
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采用非均相沉淀-热还原法制备了Fe/Si3N4颗粒复合粉末并在热处理温度1873K和0.1MPa氮气气氛下进行常压与热压烧结。通过扫描电镜(SEM)、透射电镜(TEM)、电子能谱(EDS)、X射线衍射(XRD)等方法观察Fe/Si3N4复合粉末的结构形貌及常压、热压烧结后的微观组织。结果表明:Fe/Si3N4复合粉末物相主要存在Fe相与Si3N4相,微观结构为纳米薄层 Fe均匀包覆Si3N4颗粒;高温烧结后的常压与热压样品的组织成分与微观结构有极大的不同,除了存在Si3N4相之外,常压样品金属Fe相衍射峰消失,并有晶粒粗大铁硅化合物生成,热压样品则保留有金属Fe相,并存在晶粒相对细小铁硅化合物及致密的玻璃态物质。 相似文献
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Gert Roebben Corneliu Sarbu Tanja Lube Omer Van der Biest 《Materials Science and Engineering: A》2004,370(1-2):453-458
In this paper, a commercial liquid phase sintered silicon nitride with Y2O3 and Al2O3 additives is investigated. The material is characterised by a large, and stable, internal friction peak near 1150 °C. The peak is linked with the glass transition in intergranular amorphous volumes, whose presence is confirmed with transmission electron microscopy. An estimate of the volume fraction of the amorphous phase is calculated from the difference in stiffness below and above the glass transition temperature. The procedure relies on accurate Young’s modulus data, which were obtained with the impulse excitation technique (IET). The amount of amorphous pocket phase was estimated at 12.4 vol.%. For the first time, microstructural evidence supporting this estimate is obtained, using analysis of scanning electron microscopy (SEM) images. The rather large amount of amorphous matter explains the limited high temperature potential of the material, which was primarily and successfully developed for wear applications. 相似文献
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Si2ON2 /LAS纳米复合材料的制备与性能研究 总被引:1,自引:0,他引:1
研究了Si2ON2/LAS纳米复合材料的制备和性能。结果表明,纳米β-Si3N4可在较低温度下与玻璃热压烧结制备出Si2ON/LASX纳米复合材料,材料的力学性能与生成的纳米Si2ON2含量有关,Si2ON2的含量在20%时材料的抗弯强度和断裂韧性达量高值,分别比未加Si2ON2的材料提高31%和88%。纳米Si2ON2的含量超过20%时,材料的力学性能急剧下降,其原因是材料的致密度迅速降低。 相似文献
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This work presents first-principle calculations of electronic structure and optical properties of doped α-Si3N4. It is found that B and P impurities form shallow acceptor and deep donor bands, respectively, in the band gap of α-Si3N4. Analysis of the charge neutrality level indicates that bipolar doping of α-SiNx is possible and that both n- and p-type electrical conductivity can be expected. This result can be helpful to extend the list of device applications of SiNx. Furthermore, it is shown that upon heavy doping with these impurities, the optical properties of the material are modified by doping. Both the refractive index and extinction coefficients are increased over the photon energy range 0-4 eV as a result of the doping. 相似文献
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Chun-Yuan Huang Tzu-Min Ou Cheng-Shuan Tsai Shih-Yen Lin Bang-Yu Hsu 《Thin solid films》2007,515(10):4459-4461
We have investigated the effects of silicon doping concentration within thirty-period self-assembled quantum dot (QD) layers on quantum dot infrared photodetectors (QDIPs). The lens-shaped quantum dots with the dot density of 1 × 1011 cm− 2 were observed by atomic force microscope (AFM). From the high ratio of photoluminescence (PL) peak intensities from dot layer to that from wetting layer, we have concluded that high dot density caused the short diffusion length for carriers to be easily captured by QDs. Moreover, the Si-doped samples exhibited the multi-state transitions within the quantum dots, which were different to the single level transition of undoped sample. Besides, the dominant PL peaks of Si-doped samples were red-shifted by about 25 meV compared to that of the undoped sample. It should result from the dopant-induced lowest transition state and therefore, the energy difference should be equal to the binding energy of Si in InAs QDs. 相似文献
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原位无压烧结制备Si2 N2O-Si3 N4复相陶瓷 总被引:1,自引:0,他引:1
以Y2O3和Al2O3陶瓷粉体作为烧结助剂,原位无压液相烧结制备Si3N4-Si2N2O复相陶瓷,Si2N2O相通过SiO2 Si3N4 2Si2N2O反应生成.生坯采用注凝成型制备,然后在1780℃保温2h烧结,烧结体基本由板条状的Si2N2O及长柱状的β-Si3N4晶粒构成.Si2N2O陶瓷相对于Si3N4陶瓷而言,具有优异的抗氧化性能,低的弹性模量,以及低的热膨胀系数,因此,Si2N2O-Si3N4复相陶瓷结合了两者的优异性能,并大大提高了材料的热冲击性,材料的热冲击温差即使达到1200℃,其残余强度基本上没有变化. 相似文献