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1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流多孔氧化铝陶瓷的放电等离子烧结技术制备.精品文档.ScienceDirect学科指南Porous Alumina Ceramics Fabricated by Spark Plasma Sintering多孔氧化铝陶瓷的放电等离子烧结技术制备WANG Kun, FU Zheng-yi*, PENG Yong, WANG Yu-cheng,ZHANG Jin-gong, ZHANG Qing-jie王坤，福郑毅，彭勇，王宇城，张晋宫，张庆街State Key Lab ofAdvanced Technology for Materials Syn
2、thesis and Processing, Wuhan University of Technology Wuhan, 430070, China国家重点实验室先进的材料合成与加工技术，武汉理工大学，武汉，430070，中国Received 10 August 2006; accepted 6 November 20062006年8月10收到； 2006年11月6日接受Abstract摘要Porous alumina of regular spherical particles was fabricated with the spark plasma sintering (SPS) and
3、then compared to those obtamed through conventional hot pressing (HP). The effects of the parameters of the heating process on porosity were also investigated. Microstructural studies suggest that porous ingots including regular pores be made out of regular spherical alumina particles due to the clo
4、se sphere packages. A comparative study on the relative necks of the specimens produced by SPS and HP indicates an enhancement of neck growth with SPS. Contrasting the theoretical values to the experimental results over the relative necks indicates that a proper relationship between the relative nec
5、ks and the porosity can be established by a sintering model.多孔氧化铝为规则的球形颗粒与放电等离子烧结（SPS）制备，然后比较分析通过常规热压（惠普）。同时考察了加热过程的参数对孔隙率的影响。微观结构研究表明，多孔硅锭包括定期毛孔被制造出来的规则的球形氧化铝颗粒由于接近球包。在SPS和惠普生产的标本，相对的脖子比较研究表明SPS颈部生长的增强。对比理论值的实验结果表明，在相对的脖子相对的脖子和孔隙度之间的关系可以通过烧结模型的建立。Keywords: spark plasma sintering (SPS); porous alumi
6、na ceramics; sintering neck关键词：放电等离子烧结（SPS）；多孔氧化铝陶瓷；烧结颈1 Introduction1引言 Porous alumina ceramics, which have both functional and structural properties, have been widely applied in the chemical industries, metallurgical industries, medical industries, and many other fields of engineering1. The variou
7、s design and performance characteristics of porous alumina ceramics are principally concentrated about controlled porosity and pore-size, high strength, heat and corrosion resistance, durability, shock resistance, and good permeability. There are many techniques to fabricate porous alumina ceramics,
8、 but the majority of those need to add organic polymers as pore forming materials2. However, spark plasma sintering (SPS) is suggested to be effective on the fabrication of porous alumina ceramics because it makes possible sintering and bonding at low temperature and short time by charging the inter
9、vals between powder particles with electrical energy and effectively applying a high temperature spark plasma generated momentarily3-5. Compared with hot pressing (HP) sintering, porous alumina ceramics can be manufactured by SPS at lower heating temperature, short holding time without any addictive
10、.多孔氧化铝陶瓷，具有的功能和结构特性，已被广泛应用于化学工业，冶金工业，医疗业，以及其他许多领域工程 1 。各种设计和多孔氧化铝陶瓷的性能特点，主要集中在受控的孔隙率和孔径，高强度，耐热性和耐蚀性，耐久性，耐冲击性，和良好的渗透性。有许多技术制备多孔氧化铝陶瓷，但大多数人需要添加有机聚合物材料的孔隙形成 2 。然而，放电等离子烧结（SPS）建议对多孔氧化铝陶瓷的制备是有效的因为它使烧结和粘结在较低的温度和较短的时间间隔，通过充电的电能和有效应用高温放电等离子粉末颗粒之间产生瞬间3-5。热压烧结（惠普）相比，多孔氧化铝陶瓷可由SPS在较低的加热温度，保持时间短，无任何添加剂。In this p
11、aper, porous alumina ceramics were fabricated by SPS and compared with the samples by HP; furthermore, the effects of the technique parameters on porosity and the effectiveness for the sintering necks during SPS process were discussed.在本文中，SPS制备与惠普的多孔氧化铝陶瓷样品进行了比较；此外，还讨论了对孔隙度的技术参数和在SPS烧结过程的脖子的效果。2 Ex
12、perimental Procedures2实验程序Raw materials were spherical particles of Al2O3 with an additive of ZrO, of which diameters were from 0.4 mm to 0.5 mm. 4 g of these spherical particles were put into a graphite mold and sintered using a spark plasma sintering apparatus (model SPS-1050, Sumi-tomo Coal Minin
13、g Co. Ltd. Japan). 原材料是球形颗粒的Al2O3 with an添加剂of ZrO，diameters of which were from 0.4毫米至0.5毫米4 g of these球形粒子是put into石墨模具和使用火花等离子体烧结sintered呼吸器（SPS 1050模型，大隅我煤矿业有限公司Japan）Fig.l shows the schematic diagram of SPS device employed in the experiments图1显示了SPS装置采用的实验原理图SPS processing was carried out in a v
14、acuum (1=6 Pa) by heating to the required temperature (1173 K-11253 K) at heating rate of 50 K/min-400 K/min, with 1 min-30 min of holding time and an applied pressure of 0 kPa-80 kPa. Temperature was measured by thermocouple. For comparison, the same particles were compacted using a hot-pressing (H
15、P) procedure under the same temperature with 60 min and 481kPa.SPS处理是在真空中进行（1 = 6 Pa）被加热到所需温度（1173 k-11253 K）在加热速率为50 K / min-400 Kmin，1 min-30分钟的保持时间和0 kpa-80千帕施加的压力。使用热电偶测量温度。相比之下，同一颗粒被压实采用热压（惠普）程序相同的温度下60分钟，481kpa。3 Results and Discussion结果与讨论3.1 Porosity measurement孔隙度测量Apparent porosity measure
16、ment was based on Archimedean principal method. Figs.2-5 show that the effect of the different technique parameters during the sintering process on porosity. As can be seen in Figs.2-4, apparent porosity decreases slightly with increasing sintering temperature and increasing holding time, while the
17、applied pressure has little influence on the porosity because of the high hardness and large dimension of the raw particles. In Fig.5, there is a slight decline in porosity when the heating rate goes up from 50 K/min to 100 K/min, which is followed by a roughly level off in porosity when the heating
18、 rate reaches 400 K/min. Therefore, an appropriate ascend of heating rate has a positive effect on the porosity of the samples, and there exists different optimum heating rate for different systems.显气孔率的测量是基于阿基米德主要方法。 Figs.2-5表明，在烧结过程中对孔隙度的不同工艺参数的影响。如可于图2 - 4中可以看出，表观孔隙率随烧结温度和增加保持时间略有减小，而所施加的压力有因为高硬度
19、和原料颗粒的大尺寸的影响较小的孔隙率。在图5中，有在孔隙率略有下降，当加热速率上升为50 K /分钟至100 K /分钟，这之后是在孔隙大致平整时的升温速率达到400 K / min的。因此，升温速率适当的递增有对样品的孔隙率有正面影响，并且存在不同的最佳加热速度为不同的系统。Fig.2 The effect of sintering temperature on porosity for porous Al2O3 ceramics(pressure: 48 kPa; holding time: 10 min; heating rate: 100 K/min)图2烧结温度对孔隙度的多孔氧化铝陶
20、瓷的影响 （压力48千帕;保温时间：10分钟;升温速率：100 K /分钟）Fig.3 The effect of uniaxial pressure on porosity for porous Al2O3 ceramics.(SPS temperature: 1 223 K; holding time: 15 min; heating rate:100 K/min)图3的单轴压力对孔隙度为多孔的影响 氧化铝陶瓷。 （SPS温度：1开氏223度，保温时间：15分钟;升温速率：100 K /分钟）Fig,4 The effect of holding time on porosity for
21、porous Al2O3 ceramics.(SPS temperature: 1 223 K; pressure: 0 kPa; heating rate: 100 K/min)图，保温时间对孔隙度的多孔4的影响 氧化铝陶瓷。 （SPS温度：1开氏223度，压力：0千帕;升温速率：100 K /分钟）Fig.5 The effect of heating rate on porosity for porous Al2O3 ceramics.(pressure: 0 kPa; holding time: 1 min; SPS temperature: 1 223 K)图5的加热速度对孔隙度的多
22、孔的影响 氧化铝陶瓷。 （压力：0千帕;保温时间：1分钟; SPS温度：1223 K）3.2 Microscopy observation3.2显微镜观察Fig.6 shows SEM micrographs of sintering neck of the SPS specimens at the sintering temperature of 1 173 K, an applied pressure of 80 kPa and a holding time of 5 min. As can be seen, there are necks formed at the contacts b
23、etween particles. The forms of the pores are regular.图6示出烧结的所述SPS试样在1173 K，80千帕的施加压力并在5分钟的保持时间，烧结温度颈部的SEM显微照片。如可以看到的，也有形成在颗粒之间的接触的脖子。的孔的形式是规则的。(pressure: 80 kPa; holding time: 5 min; SPS temperature: 1 173K; heating rate: 100 K/min)3.3 Calculation of relative necks相对脖子的计算Suppose all the specimens pu
24、t into the graphite die exhibited similar packing configuration, the relationship between the volume of the cylindrical samples and porosity can be depicted by these formulas.where b is the porosity of the specimens before sintering, a is the porosity of the specimens after sintering,Vb is the volum
25、e of the specimens before sintering,Va is the volume of the specimens after sintering,Vs is the total volume of all the solid particles, a changeless constant.假设所有放入石墨模具中的试样表现出类似的包装结构中，筒状的样品和孔隙的体积之间的关系可以用下列公式来描绘。其中b是在烧结前的试样的孔隙度，a为试样的孔隙率在烧结后，Vb为试样的体积烧结之前，Va为烧结后的试样的体积，Vs是所有固体的总体积颗粒，一个不变的常数。As can be s
26、een in the double-sphere model(shown in Fig.7), the growth of sintering neck is enhanced during the earlier sintering process6. The distance between the centers of the two sphere particles declines with the growing of the sintering neck.作为所用的双球模型（图7所示），可以看出，烧结颈部的生长过程中较早烧结过程中被增强6。两个球体粒子的中心间的距离下降的烧结颈部
27、的生长。 Under the assumption that the radius of sintering neck formed in earlier sintering process is small, and there is approximately no change on the diameters of the raw particles, the linear shrinkage between the centers of the two sphere particles can be 双球烧结模型 calculated by the geometrical relat
28、ionship in Fig.7 as described by these equations. 由所描述的这些方程7所示的几何关系来计算。Based on the expression pattern of Eqs.(1)一(4), the value of the radios of sintering neck and radius of particles can be calculated by Eq.(5).基于方程的表达模式（1）一（4），烧结颈部的颗粒和半径的无线电的值可以通过公式来计算（5）。Substituting the porosity of the specimen
29、s before and after sintering into Eq.(5) to reckon the theoretical value of relative necks under different sintering conditions. At the same time, an image analysis was carried out by measuring the relative necks in the SEM graphs. The comparisons between theoretical and experimental values are show
30、n in Table 1. Results indicate that the relation between relative neck and porosity described in Eq.(5) is proper.前和烧结式代入后。代样品的孔隙率（5），以估计不同的烧结条件下相对颈部的理论值。与此同时，一个图像进行分析，通过测量在SEM图中的相对的脖子。理论和实验值之间的比较示于表1中。结果表明，相对于颈部和在方程所描述的孔隙率之间的关系（5）是适当的。Table 1 The comparison between calculated and experimental data
31、of the ratios of neck and particle size (x/R) with sintering temperatures in SPS process表1 与烧结温度在SPS过程中颈部和粒度（X / R）的比值计算结果与实验数据的比较(pressure: 48 kPa; holding time: 10 min; heating rate: 100 K/min)（压力48千帕;保温时间：10分钟;升温速率：100 K /分钟）3.4 Comparing with HP3.4 与HP相比较Under the same applied pressure and the s
32、intering temperature, the samples with a holding time of 5 min in SPS process, and 60 min in HP process were examines by scanning electron microscopy(SEM). Table 2 shows that the porous alumina ceramics fabricated via SPS exhibites an enhanced densification in comparison with HP. To attain the simil
33、ar value of relative necks, the SPS temperature is lower than the HP temperature, and the holding time of SPS is shorter than that of HP.在相同的施加的压力和烧结温度，用5分钟在SPS过程，并在HP工艺60分钟的保持时间的样品进行检通过扫描电子显微镜（SEM）。表2显示，通过SPS制备的多孔氧化铝陶瓷件展示品增强的致密化中使用HP比较。为了达到相对颈部的相似值，对SPS温度比HP温度下，和SPS的保持时间比HP的短。Table 2 Comparison of
34、the ratios of neck and particle size（/R)with sintering temperatures for SPS and HP samples表1 颈部和颗粒大小（/ R）的比值与烧结温度对SPS和HP的样本比较4 Conclusions4结论(1) Apparent porosity decreases with increasing sintering temperature and increasing holding time, while the applied pressure has little influence on the poros
35、ity because of the high hardness and large dimension of the raw particles. And there exists different optimum heating rate for different systems.（1）随着烧结温度和增加保持时间的表观孔隙度减小，而所施加的压力有因为高硬度和原料颗粒的大尺寸的影响较小的孔隙率。并且存在不同的最佳升温速率为不同的系统。 (2) The comparisons between theoretical and experimental values indicate that
36、 the relation between relative neck and porosity described in is proper.（2）的理论值和实验值之间的比较表明，在中描述的相对颈部和孔隙率之间的关系是适当的。 (3) To attain the similar value of relative necks,the SPS temperature should be lower than the HP temperature, and the holding time of SPS should be shorter than that of HP.（3）为了实现相对于颈部
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