共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
AlN/玻璃复合材料的相分布对导热性能的影响 总被引:2,自引:0,他引:2
以热压烧结方法在850~1000℃的低温下制备了Al/玻璃复合材料,通过组成变化研究了复合材料热导率的变化规律,利用SEM、TEM、XRD等方法观察了AlN/玻璃复合材料的显微结构和相组成与分布,讨论了复合材料的显微结构和相组成对热导率的影响,结果表明:AlN/玻璃复合材料的热导率随玻璃相的减少而增加,低温烧结的复合材料的热导率可以达到10W/m·K以上,材料的相分布对热导率的影响表现为:当玻璃相减少,AlN晶粒相互接触时,有利于热导率的提高;当材料内部以AlN晶相为主时,材料出现晶体的导热特征,即热导率随温度的升高而下降。 相似文献
3.
4.
5.
研究了低温烧结助剂Li2O对SPS烧结AlN陶瓷烧结致密化过程、烧结体显微结构和导热性的影响.研究表明:在SPS烧结过程中,烧结助剂Li2O和Sm2O3(或Y2O3)的加入使AlN试样开始收缩并进入烧结初期阶段的温度从1550℃左右下降到1200℃以下;同时Li2O使AlN试样的烧结温度显著降低,完全致密化温度降低到1650℃左右.烧结体的显微结构表明:Li2O的加入有助于形成润湿性良好的液相,促进AlN陶瓷的液相烧结;但不利于快速烧结坯体中气体的扩散与逸出,使试样的致密度受到影响.同时,Li2O影响AlN晶粒的发育,使液相润湿性提高,晶界相均匀分布,增加了晶粒界面上的声子散射,对AlN材料的热导率产生不利影响.同时,添加1.0wt%Li2O和1.5wt%Sm2O3的AlN试样的热导率低于仅添加1.5wt%Sm2O3的试样. 相似文献
6.
7.
8.
热处理是AlN陶瓷调整结构、改善性能的有效手段.利用国产六面顶压机,在5.0GPa高压条件下,对高压烧结制备的AlN(Y2O3)陶瓷进行了热处理,研究了高压热处理对AlN陶瓷显微结构及导热性能的影响.结果表明:经5.0GPa/970℃/2h高压热处理后的AlN陶瓷材料与未热处理的试样相比,晶粒尺寸显著增大,晶粒形状越发规整,第二相均位于晶界处或者三角晶界区域,热导率达到了173.2W/(m.K),是未经过热处理试样的2.2倍.但是,将高压热处理时间延长到4h,AlN陶瓷的气孔增大,出现了反致密化现象,热导率也降低到80.9W/(m.K). 相似文献
9.
10.
低温烧结AlN陶瓷的微结构和热导率 总被引:3,自引:0,他引:3
采用CaF2,Y2O3和Li2CO3做添加剂,在低温下制备了高热导率的AlN陶瓷,通过SEM,TEM和XRD研究了AlN陶瓷在烧结过程中微结构及晶格常数的变化及其对热导率的影响。研究发现,当使用CaF2-Y2O3做添加剂时,液相对晶粒浸润性较差。不利于AlN晶格的纯化。而添加Li2O-CaF2-Y2O3的AlN陶瓷在烧结温度之前已经完成了液相的重新分布,液相与AlN晶粒之间有较好的浸润性,这促进了AlN陶瓷的致密化和AlN晶格的纯化,有利于获得较高的热导率。 相似文献
11.
S. N. Ivanov L. M. Zhukova Ya. M. Soifer E. N. Khazanov A. V. Taranov 《Inorganic Materials》2000,36(5):504-507
The thermal conductivity, dielectric properties, and strength of A1N ceramics were studied. The ceramics were prepared by
semidry pressing and sintering. Increasing the sintering time was found to increase the thermal conductivity of the ceramics
up to 200 W/(m K). A nonequilibrium-phonon-propagation method was used to analyze the effect of grain boundaries and processing
conditions on the thermal conductivity of the ceramics. 相似文献
12.
《Materials Science & Technology》2013,29(2):513-517
AbstractDense aluminium nitride ceramics were prepared by spark plasma sintering at a lower sintering temperature of 1700°C with Y2O3, Sm2O3 and Dy2O3 as sintering additives respectively. The effects of three kinds of sintering additives on the phase composition, microstructure and thermal conductivity of AlN ceramics were investigated. The results showed that those sintering additives not only facilitated the densification via the liquid phase sintering mechanism, but also improved thermal conductivity by decreasing oxygen impurity. Sm2O3 could effectively improve thermal conductivity of AlN ceramics compared with Y2O3 and Dy2O3. Observation by scanning electron microscopy showed that AlN ceramics prepared by spark plasma sintering method manifested quite homogeneous microstructures, but AlN grain sizes and shapes and location of secondary phases varied with the sintering additives. The thermal conductivity of AlN ceramics was mainly affected by the additives through their effects on the growth of AlN grain and the location of secondary phases. 相似文献
13.
14.
本文研究了掺杂CaO Y2 O3热压烧结和常压烧结AlN陶瓷的晶界相及其产生过程和除氧机制 ;分析了两种烧结工艺烧制的AlN陶瓷的晶界成份 ;测定了不同晶界相含量和晶界成份对应的AlN陶瓷的热导率 相似文献
15.
Dense aluminum nitride (AlN) ceramics were prepared by Spark Plasma Sintering with rare-earth oxide and CaF2 as sintering additives. The effect of sintering additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that those sintering additives not only promoted densification through liquid-phase sintering but also improved thermal conductivity by decreasing oxygen impurities. Thermal conductivities of samples sintered with optimum proportion of rare-earth oxide and CaF2 were higher than those of other samples. During the Spark Plasma Sintering process, the microstructures, especially the content and distribution of secondary phases, played important roles on the thermal conductivity of AlN ceramics. 相似文献
16.
17.
莫来石含量对钙长石/莫来石复相多孔陶瓷组织结构与性能的影响 总被引:1,自引:0,他引:1
以CaCO3、SiO2、α-Al2O3为原料, 采用泡沫注凝法制备了不同莫来石含量的钙长石/莫来石复相多孔陶瓷, 研究了莫来石含量对复相多孔陶瓷的体积密度、气孔率、抗压强度、热导率及微观组织和结构的影响. 结果表明, 莫来石含量对气孔率有很大的影响, 烧结过程中液相出现引起的收缩是气孔率下降的主要原因; 在气孔率相近的情况下, 莫来石含量较高试样的抗压强度和热导率也较高, 致密的孔壁、长柱状的莫来石晶粒使得复相多孔陶瓷的抗压强度提高. 所制备的钙长石/莫来石复相多孔陶瓷的开口气孔率介于60.8%~75.2%, 抗压强度为12.94~36.95 MPa, 热导率为0.30~1.33 W/(m·K). 相似文献
18.
R. J. Bruls A. A. Kudyba-Jansen P. Gerharts H. T. Hintzen R. Metselaar 《Journal of Materials Science: Materials in Electronics》2002,13(2):63-75
MgSiN2 ceramics with and without sintering additives were prepared by hot uni-axial pressing. For the sintered samples the lattice parameters, secondary phases, density, oxygen and nitrogen content, microstructure, oxidation resistance, hardness, elastic constants, linear thermal expansion coefficient and thermal diffusivity were determined. By suitable processing, fully dense MgSiN2 ceramics with an oxygen content <1.0 wt % could be obtained. The size of the MgSiN2 grains increased with increasing hot-pressing temperature and time. Transmission electron microscopy (TEM) showed the absence of grain-boundary phases and that secondary phases are present as separate grains in the MgSiN2 matrix. Scanning thermal microscopy (SThM) thermal imaging revealed a thermal barrier at the grain boundaries. The influence of the microstructure as well as the oxygen content and defect chemistry on the thermal diffusivity is limited. Supported by some theoretical considerations it is concluded that the thermal conductivity of the MgSiN2 ceramic samples is determined by intrinsic phonon-phonon scattering and will not exceed 35 W m-1K-1 at 300 K in agreement with the maximum observed value of 21–25 W m-1 K-1. 相似文献
19.
SiC陶瓷具有优异的力学性能、热学性能、抗热震性能、抗化学侵蚀性能和抗氧化性能,是热交换器设备的常用基体材料。由于原料、成型工艺、烧成工艺和烧结助剂等因素制约,SiC陶瓷含有较多气孔、晶界、杂质和缺陷,导致其常温热导率(≤270 W·m^(-1)·K^(-1))低于碳化硅单晶材料(6H-SiC,490 W·m^(-1)·K^(-1)),且不同制备工艺下热导率存在较大差异。本文主要分析了温度、气孔、晶体结构和第二相对SiC陶瓷导热性能的影响,归纳了热压烧结法、放电等离子烧结法、无压烧结法、重结晶烧结法和反应烧结法制备高导热SiC陶瓷的特点,对优化烧结助剂种类及含量、高温热处理和添加高导热第二相等改善SiC陶瓷导热性能的主要措施进行阐述,并展望了未来高导热SiC陶瓷的研究方向,为未来制备低成本、高导热SiC质热交换器提供理论参考。 相似文献