共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
三维打印结合反应烧结制备多孔氮化硅陶瓷 总被引:4,自引:4,他引:0
以硅粉(Si)为起始原料,糊精为粘结剂,采用三维打印(3DP)快速成型技术制备出多孔硅坯体,通过反应烧结得到高孔隙率的氮化硅(Si3N4)陶瓷。研究了反应烧结工艺对3DP多孔Si3N4陶瓷性能的影响。结果表明:3DP成型的硅坯体采用阶梯式升温机制,可得到抗弯强度为(5.1±0.3)MPa,孔隙率达(74.3±0.6)%的多孔Si3N4陶瓷。反应烧结后,样品的线收缩率小于2.0%。三维打印结合反应烧结法实现了复杂形状陶瓷构件的无模制造与净尺寸成型。 相似文献
3.
4.
5.
以硅粉(Si)为起始原料, 氧化钇(Y2O3)为烧结助剂, 利用干压成型工艺制备出不同气孔率的多孔硅坯体, 通过反应烧结得到高强度多孔氮化硅(Si3N4)陶瓷. 研究了Y2O3添加量在不同升温制度下对于氮化率的影响, 以及1500~1750℃后烧结对多孔材料强度的影响. 结果表明: 添加9%Y2O3的样品具有较高的氮化率, 主要是Y2O3与Si粉表面的SiO2在较低的温度下反应生成了Y5Si3O12N. 在不同的反应条件下可得到气孔率为30%~50%, 强度为160~50MPa的样品. 在1750、 0.5MPaN2气压下对样品进行后处理, α-Si3N4完全转变成柱状β-Si3N4, 晶型转变有利于强度提高,气孔率为46%的多孔Si3N4其强度可达140MPa. 相似文献
6.
在总结多年来系列试验研究基础上,提出了垂直烧结多孔层上沸腾传热的物理模型。描述了多孔层内沸腾热及流运过程,同时考虑了多孔层上液膜流速及厚度对多孔层内气流流动及传的影响。这些方面的研究为潜在的工业应用提供了理论论据。 相似文献
7.
8.
9.
10.
对氮化硅陶瓷的以应填隙再煤结做了细致的研究,结果表明,用硅粉代替部分氮化硅,在1150℃,1250℃,1350℃分阶段保温氮化后,再经过无压烧结,可以得到烧成收缩小,抗弯强度大的氮化硅陶瓷材料。 相似文献
11.
12.
热氧化多孔硅制备及其干涉特性研究 总被引:1,自引:0,他引:1
采用电化学阳极氧化法制备彩色薄层多孔硅,经高温热氧化处理后形成稳定的热氧化多孔硅.研究电化学制备条件对热氧化多孔硅的干涉效应和光学厚度的影响,分析热氧化处理前后多孔硅的稳定性.结果表明,在可见光波长范围内,所制备的热氧化多孔硅反射光谱出现一定规律性的干涉条纹,表现出明显的反射干涉现象;随阳极氧化时间、电流密度和HF浓度增大,热氧化多孔硅光学厚度呈增大趋势,当阳极氧化时间为30s、电流密度为520mA/cm2、v(HF):v(C2H5OH)为2:1~5:2时,制备的热氧化多孔硅干涉条纹均匀且光学厚度较大;热氧化处理后,多孔硅结构中的Si-Hx键被Si-O键所取代,其反射干涉特性非常稳定. 相似文献
13.
A. K. Mukhopadhyay 《Bulletin of Materials Science》2001,24(2):105-109
Repeated indentation fatigue (RIF) experiments conducted on the same spot of different structural ceramics viz. a hot pressed
silicon nitride (HPSN), sintered alumina of two different grain sizes viz. 1 μm and 25 μm, and a sintered silicon carbide
(SSiC) are reported. The RIF experiments were conducted using a Vicker’s microhardness tester at various loads in the range
1–20 N. Subsequently, the gradual evolution of the damage was characterized using an optical microscope in conjunction with
the image analysing technique. The materials were classified in the order of the decreasing resistance against repeated indentation
fatigue at the highest applied load of 20 N. It was further shown that there was a strong influence of grain size on the development
of resistance against repeated indentation fatigue on the same spot. Finally, the poor performance of the sintered silicon
carbide was found out to be linked to its previous thermal history. 相似文献
14.
Zirconium phosphate (ZrP2O7) bonded silicon nitride (Si3N4) porous ceramics were prepared using starch powder as the pore forming agent and pressureless sintering technique. The obtained results show that the porosity of the sintered starch processed 25 wt.% ZrP2O7 bonded Si3N4 porous ceramics is 36-62.3%. All the samples exhibit surprisingly low linear shrinkage. The pores are formed by the continuous reaction of ZrP2O7 at ~ 250 °C and burnout of starch at ~ 550 °C, during which a large amount of pores with pore sizes of less than 0.5 μm and ~ 10 μm are formed. 相似文献
15.
Sinterable silicon carbide powders were prepared by attrition milling and chemical processing of an acheson type α-SiC. Pressureless
sintering of these powders was achieved by addition of aluminium nitride together with carbon. Nearly 99% sintered density
was obtained. The mechanism of sintering was studied by scanning electron microscopy and transmission electron microscopy.
This study shows that the mechanism is a solid state sintering process. 相似文献
16.
Duan Li Elisângela Guzi de Moraes Peng Guo Ji Zou Junzhan Zhang Paolo Colombo 《Science and Technology of Advanced Materials》2014,15(4)
Silicon nitride foams were prepared by direct foaming and subsequent rapid sintering at 1600 °C. The intense thermal radiation generated under the pressureless spark plasma sintering condition facilitated necking of Si3N4 grains. The prepared foams possessed a porosity of ~80 vol% and a compressive strength of ~10 MPa, which required only ~30 min for the entire sintering processes. Rapid growth of one-dimensional SiC nanowires from the cell walls was also observed. Thermodynamic calculations indicated that the vapor–liquid–solid model is applicable to the formation of SiC nanowires under vacuum. 相似文献
17.
为获得适用于苛刻环境下的高强度、高气孔率氮化硅陶瓷,采用原位生成纳米碳化硅增强相的方法,以提高材料的性能.从改善凝胶注浆料稳定性着手,利用铈离子(Ce4+)和醇羟基组成的氧化还原体系对炭黑表面进行接枝改性,将改性后的炭黑与氮化硅粉配合,用于制备多组分凝胶注模成型用复合浆料.探讨了水溶液中丙烯酰胺在炭黑表面接枝反应的影响因素,利用红外谱、热失重、透射电镜等分析手段验证了炭黑表面的接枝情况.研究表明:经接枝改性的炭黑在水分散体系中具有良好的分散稳定性,炭黑经接枝处理后其阻聚性明显下降,可以制备出均一、稳定的多组分浆料,很好地应用于氮化硅凝胶注模成型工艺. 相似文献
18.
19.
以p型单晶硅片为研究对象,在单晶硅片表面采用化学腐蚀方法制备多孔硅层,通过实验选取制备多孔硅的最佳工艺条件,采用SEM观察多孔硅表面形貌,以及用微波光电导法测试少子寿命的变化情况。结果表明,在相同的腐蚀溶液配比条件下腐蚀11min得到的多孔硅层的表面形貌最好,孔隙率最大。在850℃下热处理150min时样品少子寿命的提高达到最大,不同腐蚀时间的样品少子寿命提高程度不同,腐蚀11min的样品少子寿命提高最大,约有10%左右。多孔层的形成伴随着弹性机械应力的出现,引起多孔层-硅基底界面处产生弹性变形,这有利于缺陷和金属杂质在界面处富集。另外,多孔硅仍具有晶体结构,但其表面方向上的晶格参数要比初始硅的晶格参数大,也有利于金属杂质向多孔层迁移。 相似文献