无压浸渗法制备氧化态SiC颗粒增强铝基复合材料

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张强, 姜龙涛, 武高辉. 无压浸渗法制备氧化态SiC颗粒增强铝基复合材料. 无机材料学报, 2012, 27(4): 353-357
ZHANG Qiang, JIANG Long-Tao, WU Gao-Hui. Fabrication of Oxidized SiC Particles Reinforced Aluminum Matrix Composite by Pressureless Infiltration Technique. Journal of Inorganic Materials, 2012, 27(4): 353-357 复制到剪切板

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无压浸渗法制备氧化态SiC颗粒增强铝基复合材料

张强, 姜龙涛, 武高辉

哈尔滨工业大学材料科学与工程学院, 哈尔滨150001

张强(1976-), 男, 副教授. E-mail:zhang_tsiang@hit.edu.cn

基金:教育部留学回国人员科研启动基金;

摘要

研究了SiC颗粒在1000~1200℃的氧化行为, 其氧化增重率与保温时间符合抛物线规律, 氧化增重受扩散过程控制, 氧化激活能为219 kJ/mol. 采用预氧化处理的SiC颗粒为增强体, 含Si、Mg的铝合金为基体, 通过无压浸渗方法制备了SiC_p/Al复合材料, 分析了复合材料的微观组织与界面形貌, 探讨了无压浸渗机理. 复合材料中颗粒分布均匀, 无偏聚现象. 材料制备过程中存在界面反应, SiC颗粒表面的氧化层与铝合金中的Mg、Al反应形成了一定数量的MgAl₂O₄. 界面反应的存在提高了润湿性, 促进了无压自发浸渗.

关键词: SiC颗粒; 氧化; 无压浸渗; 界面反应

中图分类号:TB331 文献标志码:A 文章编号:1000-324X(2012)04-0353-05

Fabrication of Oxidized SiC Particles Reinforced Aluminum Matrix Composite by Pressureless Infiltration Technique

ZHANG Qiang, JIANG Long-Tao, WU Gao-Hui

School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

Fund:Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry;

Abstract

The oxidation behavior of SiC particles in the temperature range from 1000℃ to 1200℃ was investigated. The dependence of weight gain and oxidation time was parabolic and the oxidation behavior was controlled by diffusion process, with a oxidation activation energy of 219 kJ/mol. Using oxidized SiC particles as reinforcement and aluminum alloy containing Si and Mg as matrix, a SiC_p/Al composite was fabricated by pressureless infiltration technique. The microstructure and interfacial morphology were analyzed and the pressureless infiltration mechanisms were discussed. The particles were distributed uniformly in the composite, without particles agglomeration. Interfacial reactions were found in the composite and the product was identified as MgAl₂O₄, formed by the reactions between surface oxide layer of SiC particles and Mg, Al in the matrix. The interfacial reactions enhanced the wettability and promoted the spontaneous infiltration process.

Keyword: SiC particles; oxidation; pressureless infiltration; interfacial reaction

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颗粒增强铝基复合材料具有制备工艺灵活、比强度和比模量高、热物理性能优异且可设计等优点^{[ 1, 2, 3]}, 在航空、航天、汽车、电子等诸多领域中具有广阔应用前景. 但是颗粒增强铝基复合材料制备工艺复杂、成本较高, 限制了它的进一步发展和应用, 几种主要制备方法包括粉末冶金、搅拌铸造、压力铸造和喷射成型等都不能解决该难题. Aghajanian等^{[ 4]}在金属直接氧化工艺的基础上开发了铝基复合材料的无压浸渗工艺, 工艺简单, 不需要昂贵的设备, 可以实现复杂制品和材料的一体成型, 成本较固相法和传统的液相法更低^{[ 2, 4, 5]}; 并且可以利用材料设计的方法来设计最终需要的复合材料性能和界面结构, 从而充分发挥增强体的强化作用, 获得理想的微观组织和性能.

对于SiC/Al复合材料, 改善SiC-Al系统的润湿性对于无压浸渗制备具有重要的意义. SiC颗粒表面形成的SiO₂薄膜具有比SiC更低的表面能, 可以改善润湿, 促进渗透. 本工作首先研究SiC颗粒的高温氧化行为, 在此基础上, 选用氧化态SiC颗粒, 采用无压浸渗方法制备SiC_p/Al复合材料, 并研究复合材料的微观组织与界面形貌, 分析复合材料的无压浸渗机理.

1 试验

1.1 SiC颗粒氧化试验

一般地, SiC上生长SiO₂氧化层的最佳温度在1000~1400℃之间. 本实验的SiC颗粒的平均粒度为10 μm, 氧化温度选取1000℃、1100℃和1200℃. 将多组10 g SiC颗粒分别置于刚玉坩锅, 放入空气炉中, 以15 ℃/min的速度加热到高温, 每隔一定时间从炉中取出试样, 进行称重, 得到氧化增量与保温时间的关系.

1.2 复合材料制备与分析

选用1100℃保温4 h的SiC颗粒, 基体合金为自配铝合金, 主要的合金元素为Si和Mg. 试验中, 首先将SiC颗粒与少量的PVA(聚乙烯醇)溶液混合, 采用机械加压的方式制备SiC颗粒预制体(45vol%). 然后于400℃保温1 h进行脱脂, 再加热到1100℃保温2 h对预制体进行烧结, 使之具有一定的强度. 接着将颗粒预制体与基体铝合金一起放入加热炉中, 在流动的氮气环境中加热至1000℃, 保温1 h后空冷, 得到SiC_p/Al复合材料.

复合材料和粉体的组织观察及元素分析在HITACHI S-4700扫描电镜上进行. 采用PhilipsTecnai-20型透射电子显微镜观察复合材料的界面形貌. 粉末的XRD分析在日本理学株式会社D/max-1β旋转阳极X射线衍射仪上进行, 采用Cu阳极, 石墨单色器, K_α波长为0.15405 nm.

2 试验结果与讨论

2.1 SiC颗粒氧化行为

图1为SiC颗粒的增重率与氧化时间的关系. 从图中可以看到, 在氧化过程中, 氧化温度和时间对氧化层增重率均有影响. 在恒定温度下, 初始时氧化速率较快, 而经过一段时间后速度变缓: SiC颗粒的氧化增重率与保温时间近似成抛物线关系.

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	图1 不同氧化温度下 SiC颗粒的增重率与氧化时间的关系Fig. 1 Variation in weight gain of SiC particles with oxidation time at different oxidation temperatures

在高氧分压(如空气中)的情况下, SiC的氧化层主要为SiO₂, 氧化反应如式(1)和(2)所示^{[ 6, 7]}:

(1)

(2)

在氧化初期, SiO₂膜很薄, 氧化剂比较容易通过, 且供应充足. 氧化层的生长主要取决于在SiC表面上氧化反应的快慢, 速度较快. 一段时间以后, 由于起始氧化层阻碍了氧化剂与SiC表面直接接触, 势必影响气相原子的纵深扩散. 其后的继续氧化是氧化剂扩散穿过已生成SiO₂向内部运动, 到达SiO₂-SiC界面后继续反应^{[ 6]}. 在氧分子与硅反应的同时, 氧分子与其表面的碳原子反应, 生成碳氧化合物, 如CO、CO₂等, 并向相反的方向扩散, 逸出表面. 氧化层薄膜越厚, 扩散速率越小, 导致在SiC表面反应中氧化剂不充足, SiO₂厚度随时间延长而变化缓慢^{[ 6]}, 氧化遵循抛物线规律, 如图1所示.

2.2 SiC颗粒氧化激活能

SiC颗粒的增重率与氧化时间基本上成抛物线关系, SiC颗粒氧化反应受扩散过程所控制, 可用式(3)进行表述:

(3)

式中 Δm _t /m为SiC颗粒氧化增重率; t为氧化处理时间; K为氧化速率常数.

利用图1中的数据, 得到SiC颗粒在不同温度下的氧化速率常数 K, 以ln K与绝对温度的倒数 (1 /T )作图, 结果如图2所示. 线性回归后, 根据Arrhenius方程, 得出该温度范围内SiC颗粒氧化反应的激活能为219 kJ/mol. 研究表明^{[ 8]}, SiC氧化反应激活能为134~498 kJ/mol, 与SiC颗粒的原始尺寸相关. 颗粒愈大, 相应减少SiC粒子间的界面, 使沿SiC粒子界面氧化的程度降低, 抗氧化能力提高.

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	图2 ln K与1/ T的关系曲线Fig. 2 Relationship between ln K and 1/ T

2.3 无压浸渗SiC_p/Al复合材料的微观组织与界面反应

采用经过1100℃保温4 h处理的氧化态SiC颗粒(氧化层厚度约为150 nm), 通过无压浸渗方法制备了SiC_p/Al复合材料. 原始的SiC颗粒由SiC结晶块经粉碎制成, 表面存在一层极薄的氧化层和Si⁴⁺等化合价不饱和离子^{[ 9]}, 易吸附杂质和气体, 阻碍SiC颗粒与铝熔体的直接接触. 预氧化处理后, SiC颗粒表面变得清洁, 氧化层增厚且致密, 表面化学吸附的气体减少, 有助于复合材料的浸渗过程.

图3为复合材料的背散射组织照片, 可以看到, SiC颗粒为暗灰色, 在铝基体中分布均匀, 无团聚现象. 颗粒均匀分布的微观组织有利于复合材料在承载时缓和应力集中, 提高材料的力学性能. 在复合材料中发现了弥散分布的白色块状组织(如图中箭头所示). 元素分析结果表明, 其对应于基体中的Si, 为基体铝合金凝固后形成的初生Si相.

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	图3 SiC_p/Al复合材料的背散射组织Fig. 3 Backscattering image of SiC_p/Al composite

复合材料的性能较为优异, 弯曲强度为400 MPa, 优于文献中采用相同制备方法得到复合材料的强度值^{[ 10, 11]}; 热膨胀系数(20~100℃)为12.1×10^-6/℃, 增强体SiC颗粒的含量为45vol%, 可以通过基体/增强体界面制约基体合金的热膨胀, 导致复合材料热膨胀系数明显小于铝合金.

图4为铸造态SiC_p/Al复合材料的TEM照片可以看到, 在SiC表面存在块状的界面反应物. 对反应物进行了衍射分析, 结果如图4(b)所示, 表明反应物为镁铝尖晶石(MgAl₂O₄). MgAl₂O₄比SiC更具有金属性, 可以改善Al与SiC颗粒之间的润湿, 促进渗透.

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	图4 铸造态SiC_p/Al复合材料的TEM照片Fig. 4 TEM images of as-cast SiC_p/Al composite(a) SiC_p/Al composite (b) SAED of [111]MgAl₂O₄(c) SAED of SiC

为了进一步验证界面反应物的种类, 利用酸性溶液将从复合材料中提取出来, 进行XRD分析与颗粒形貌观察. 首先将少量块状试样浸泡在溶液中, 一段时间后取出颗粒残留物, 对其进行清洗、烘干和取粉. 图5为提取的含有界面反应物的SiC颗粒的XRD结果, 主要物相包括SiC和MgAl₂O₄. 其中, SiC来自颗粒本身, MgAl₂O₄则来源于界面反应物.

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	图5 SiC_p/Al复合材料中提取颗粒的XRD图谱Fig.5 XRD pattern for the particles extracted from SiC_p/Al composite

图6为SiC颗粒在复合材料制备前后的SEM表面形貌. 制备前经过预先氧化处理的SiC颗粒表面吸附着少量微细粉末, 但无其它杂物, 颗粒边缘棱角分明; 从复合材料中提取的颗粒中, 边缘棱角钝化, 其表面可以看到明显的块状界面反应物, 呈不连续分布. 块状反应物(图(b)“+”处)的EDS分析结果如图6(c)所示, 其主要元素包含O、Mg、Al和Si. 其中, O、Mg、Al来源于反应物, Si的存在可能是由于反应产物较薄, X射线探测器测到了产物下方SiC颗粒. 以上结果证明, 界面反应产物MgAl₂O₄的存在.

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	图6 预氧化SiC与复合材料中提取颗粒的SEM照片及EDS能谱Fig. 6 SEM morphologies of pre-oxidized SiC and particles extracted from composite(a) Pre-oxidized SiC particles; (b) Particles extracted from composite; (c) EDS result of the ‘cross’ marked in Fig. 6 (b)

2.4 无压浸渗机理分析

铝基体中的Mg是一种活泼元素, 当铝合金熔化时, 易于富集于铝熔体的表面. 在SiC_p/Al复合材料的无压浸渗过程中, 颗粒表面的SiO₂薄膜将与铝合金中的Mg、Al反应形成MgAl₂O₄, 如式(4)、(5)所示:

2Mg+SiO₂=2MgO+Si (4)

2MgO+4Al+3SiO₂=2MgAl²O₄+3Si (5)

在金属-陶瓷构成的复合体系中, 如发生溶解、扩散或化学反应时, 瞬时接触角cos θ( t)为^{[ 12]}:

(6)

其中, cos θ ⁰和 σ ⁰_LV分别为没有界面反应时的接触角和液体表面张力, Δσ( t)为由于界面反应导致界面能的改变量, Δ G( t)为由于形成新相而导致的系统吉布斯自由能的变化. 界面反应的进行, 将导致系统自由能的降低, 即Δ G( t)<0; 根据Aksay等的研究, 由于化学反应的存在, 界面能将迅速减小至最小值, 之后随着反应的进行, 由于界面固、液相间组员浓度梯度减小, 界面能逐渐增大, 并趋于达到平衡态的静态界面能, 整个阶段Δ σ( t)<0. 因此, 在两个方面的综合作用下, 将导致cos θ( t)值增大, 有利于降低金属-陶瓷最终的润湿角, 并促进二者的润湿. 因此合金中的Mg元素可以诱发界面的化学反应^{[ 10, 11]}, 起到反应润湿的效果, 促进了自发浸渗. 随着界面反应和浸渗过程的不断进行, 逐渐形成连续、致密的SiC_p/Al复合材料.

SiC_p/Al复合材料的无压浸渗还与以下几个方面的因素有关: (1) 基体中的Mg降低了铝合金熔体的表面张力^{[ 13]}, 有利于提高其润湿性; (2) 铝合金中添加Si元素可以降低合金熔体的粘度, 增加其流动性和浸渗速率, 有利于铝熔体在颗粒间的浸渗过程; (3) 较高的浸渗温度起到了加剧界面反应速率和降低铝熔体的表面张力等多方面的作用, 促进了无压浸渗过程.

3 结论

1) 在1000~1200℃的温度范围内, SiC颗粒的氧化增重率与保温时间呈抛物线关系, 其氧化激活能为219 kJ/mol.

2) 采用无压浸渗法可以制备浸渗完全的SiC_p/Al复合材料, 颗粒分布均匀, 无偏聚现象.

3) 铸造态SiC_p/Al复合材料界面处有镁铝尖晶石(MgAl₂O₄)形成, 界面反应的存在起到了反应润湿的效果, 促进了自发浸渗.

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2001

0.0

... 颗粒增强铝基复合材料具有制备工艺灵活、比强度和比模量高、热物理性能优异且可设计等优点^[1,2,3], 在航空、航天、汽车、电子等诸多领域中具有广阔应用前景 ...

2010

0.0

. 2010, 7(6):837-845

Al₂O₃–B₄C–Al Composite Material Systems via Pressureless Infiltration Methods

Richard T. Fox † ,Robert A. Newman,Aleksander J. Pyzik andChan Han

The Dow Chemical Company, Midland, MI

Modification of the Al₂O₃–Al system's chemistry via the addition of B₄C is described and is shown to result in fully dense structures via wetting techniques at high temperatures, without the need for pressure-assisted infiltration. The relationships between the surface area of boron carbide and alumina powders, the effectiveness of infiltration, the material chemistry following infiltration, and the resulting mechanical properties of Al₂O₃–B₄C–Al composites are evaluated. Additional approaches, including the incorporation of aluminum metal powder as an additional wetting agent before infiltration, are described in conjunction with a variation of both the surface areas and the volumetric ratios of inert Al₂O₃ to reactive B₄C phases. These methods can provide the means to achieve low-cost metal matrix composites in both vacuum and argon infiltration environments, and represent an approach that enables the generation of articles with complex geometries, requiring minimal secondary finishing treatment.

... Aghajanian等^[4]在金属直接氧化工艺的基础上开发了铝基复合材料的无压浸渗工艺, 工艺简单, 不需要昂贵的设备, 可以实现复杂制品和材料的一体成型, 成本较固相法和传统的液相法更低^[2,4,5] ...

2006

0.531

1.106

. 2006, 21(6):1405-1410 DOI:10.3724/SP.J.1077.2006.01405

Fabrication and thermophysical properties of SiC_p/Al metal-matrix composites by SPS

State Key Laboratory of Advanced Technology for Materials ynthesis and Processing, Wuhan University of Technology, Wuhan 430070, China

SiC particles, pure aluminum powder and silicon powder were applied to prepare SiC particles reinforced Al-matrix composites for electronic packaging application. Al-matrix composites reinforced with SiC particles were fabricated by SPS. The composites were dense and SiC particles distributed homogenously in Al-matrix. According to the investigation of SPS process, the sintering process of the composite, belongs to a reactive sintering, the majority of sintering shrinkage can be finished in a short period. Effects of SiC volume fraction and particles sizes
on thermal conductivity and coefficient of thermal expansion were investigated. The results indicate that thermal conductivity and coefficient of thermal expansion decrease with the increase of SiC volume fraction, and thermal
conductivity increases but coefficient of thermal expansion decreases with the increase of SiC particles sizes.

采用纯粉末, 通过SPS烧结制备了组织均匀、致密且体积分数高的SiCp/Al电子封装材料. 通过对SPS烧结现象的研究, 认为该复合材料的SPS烧结过程属于反应性烧结, 大部分收缩在极短时间内完成; 另外对SiC体积分数和SiC颗粒尺寸对热导率、热膨胀系数的影响进行了研究, 发现SiC体积分数越高, 复合材料的热导率和热膨胀系数越低; SiC颗粒粒径增大, 复合材料的热导率增高, 而热膨胀系数减小.

1991

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J Mater Sci. 1991, 26(2):447-454

The fabrication of metal matrix composites by a pressureless infiltration technique

M. K. Aghajanian (1) , M. A. Rocazella (1) , J. T. Burke (1) , S. D. Keck (1)

1.Lanxide Corporation, 19714-6077, Newark, Delaware, USA

A novel technique for fabricating metal matrix composites by the spontaneous (pressureless) infiltration of filler preforms with molten aluminium alloys is described. Numerous reinforcing materials, including Al₂O₃ and SiC of various configurations, such as particles, agglomerates, and fibres, have been incorporated as fillers. The effects of processing variables, such as alloy chemistry, process temperature, and filler material, on the infiltration kinetics and resultant microstructures are discussed. Comparisons with existing infiltration technology and preliminary composite properties are presented.

2008

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. 2008, 39(1):108-115 DOI:10.1007/s11663-007-9111-9

Kinetics of pressureless infiltration of Al-Mg melts into porous alumina preforms

1.Indian Institute of Science Department of Materials Engineering Bangalore 560012 India 2.John F. Welch Technology Center, General Electric Material Mechanics Lab Bangalore 560066 India

Effective “hydrodynamic” radii governing infiltration kinetics of reactive Al-Mg melts into alumina preforms were found to be three orders of magnitude smaller than the average pore size of the packed bed and also smaller compared with the kinetics for a nonreactive system. A sinusoidal capillary model was developed to predict flow kinetics within the packed bed. For the reactive system, two factors were ascribed for additional melt retardation: (1) different intrinsic wettabilities of the two liquids on alumina, thereby leading to significantly different “effective” local contact angles; and (2) local solute depletion from the meniscus, which was incorporated as a time-dependent contact angle.

2000

0.0

... 在高氧分压(如空气中)的情况下, SiC的氧化层主要为SiO₂, 氧化反应如式(1)和(2)所示^[6,7]: ...

... 其后的继续氧化是氧化剂扩散穿过已生成SiO₂向内部运动, 到达SiO₂-SiC界面后继续反应^[6] ...

... 氧化层薄膜越厚, 扩散速率越小, 导致在SiC表面反应中氧化剂不充足, SiO₂厚度随时间延长而变化缓慢^[6], 氧化遵循抛物线规律, 如图1所示 ...

1998

2.163

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Journal of Materials Science. 1998, 33(2):535-547

A theoretical and experimental approach to the active-to-passive transition in the oxidation of silicon carbide: Experiments at high temperatures and low total pressures

B Schneider (1) , A Guette, R Naslain, M Cataldi (2) , A Costecalde

1.Laboratoire des Composites ThermoStructuraux (UMR 47 CNRS-SEP-UB1), Domaine universitaire, 3 allee de La Boetie, 33600, Pessac, France 2.Societe Europeenne de Propulsion, Le Haillan, BP 37, 33165, Saint-Medard-en-Jalles, France

Active-to-passive oxidation transition in chemical vapour deposited β-SiC was investigated in the temperature range 1300≤T≤1700°C under low total pressures (100≤Ptot≤800 Pa) and relatively high linear gas flow rates (10≤Vgas≤60 m s1) by thermogravimetric analysis. For given T, Ptot and Vgas, the oxygen partial pressure at the transition, PtO2, corresponds to the value where the mass-loss rate per unit area of the oxidized sample, R, is maximum. Logarithms of PtO2 are linear functions of reciprocal temperature for given Ptot, and Vgas. Vgas has a significant influence on the position of the transition log(PtO2)–T-1 line. PtO2 is also slightly affected by an increase of Ptot from 100 Pa to 800 Pa. In passive oxidation at high temperatures (>1500°C), large bubbles form in the silica film which is then disrupted leading to a loss of material. In active oxidation, R significantly depends on Vgas: the kinetics is diffusion or mass transfer controlled under the conditions investigated in the present study. In both active and passive oxidation regimes, a mass loss of the test specimen is always observed; an explanation is proposed.

... 在高氧分压(如空气中)的情况下, SiC的氧化层主要为SiO₂, 氧化反应如式(1)和(2)所示^[6,7]: ...

2000

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... 研究表明^[8], SiC氧化反应激活能为134~498 kJ/mol, 与SiC颗粒的原始尺寸相关 ...

1992

0.0

... 原始的SiC颗粒由SiC结晶块经粉碎制成, 表面存在一层极薄的氧化层和Si⁴⁺等化合价不饱和离子^[9], 易吸附杂质和气体, 阻碍SiC颗粒与铝熔体的直接接触 ...

2000

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. 2000, 108(1):null-null

Optimum conditions for pressureless infiltration of SiC_p preforms by aluminum alloys

... 复合材料的性能较为优异, 弯曲强度为400 MPa, 优于文献中采用相同制备方法得到复合材料的强度值^[10,11] ...

... 因此合金中的Mg元素可以诱发界面的化学反应^[10,11], 起到反应润湿的效果, 促进了自发浸渗 ...

1998

1.212

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Metall and Mat Trans A. 1998, 29(12):3087-3095

Fabrication of Al-3 Wt pct Mg matrix composites reinforced with Al₂O₃ and SiC particulates by the pressureless infiltration technique

Kon Bae Lee (1) , Youn Su Kim (1) , Hoon Kwon (1) (2)

1.the School of Metallurgical and Materials Engineering, Kookmin University, 136-702, Seoul, Korea 2.Center for Advanced Aerospace Materials, 790-784, Pohang, Korea

In Al-3 wt pct Mg/Al₂O_3p (or SiC_p) composites fabricated by the pressureless infiltration method, the infiltration behavior of molten metal, the mechanical properties, and the interfacial reactions were investigated. The spontaneous infiltration of the molten Al-3 wt pct Mg alloy into the powder bed occurred at a relatively low temperature (700 °C for 1 hour under a nitrogen atmosphere). Spontaneous infiltration of the molten metal is related to the formation of Mg₃N₂ by the reaction of Mg and nitrogen. The tensile strength and 0.2 pct offset yield strength and elongation tend to decrease with increasing infiltration temperature and time, because of an increased interfacial reaction. In Al-3Mg/Al₂O₃ composites, MgAl₂O₄ was observed at interfaces between Al₂O₃ and the matrix, as well as at oxide films of the Al powder surface. In addition, MgO was observed at interfaces between Al₂O₃ and the matrix. On the other hand, Al₄C₃ was formed at interfaces between SiC and the matrix in Al-3Mg/SiC composites. In addition, MgAl₂O₄ was observed as a reaction product at the interfaces between oxide films of SiC and the matrix, as well as at oxide films of the Al powder surface. Since the Si released as a result of the interfacial reaction is combined with Mg, age hardening can occur by the precipitation of Mg₂Si via T6 treatment.

... 复合材料的性能较为优异, 弯曲强度为400 MPa, 优于文献中采用相同制备方法得到复合材料的强度值^[10,11] ...

... 因此合金中的Mg元素可以诱发界面的化学反应^[10,11], 起到反应润湿的效果, 促进了自发浸渗 ...

1993

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... (t)为^[12]: ...

1986

2.163

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J Mater Sci. 1986, 21(8):2787-2792

The surface tension of liquid pure aluminium and aluminium-magnesium alloy

C. Garcia-Cordovilla (1) , E. Louis (1) (2) , A. Pamies (1)

1.Centro de Investigacón y Desarrollo, Empresa Nacional del Alumino, SA Apartado 25, 03080, Alicante, Spain 2.Departamento de Fisica, Universidad de Alicante, Apartado 99, 03080, Alicante, Spain

This paper discusses the results of several experiments designed to further illustrate the recent findings of the present authors according to which, if a virtually leak-fee maximum bubble pressure system is used to measure the surface tension of liquid aluminium, a surface tension around 1100 mJ m⁻² is first obtained, decreasing to the oxidized value (around 865 mJ m⁻²) as the experiment proceeds and oxygen enters the system mainly through the capillary walls. The peculiarities and difficulties inherent to the maximum bubble pressure method are illustrated. For instance, a study of the time needed for the surface tension to decrease to the oxidized value as a function of temperature reveals the important role played by the vapour pressure in the process. This is further illustrated by considering Al-Mg alloys, as magnesium has a different heat of vaporization and a much larger vapour pressure than aluminium at the measuring temperatures. Results for the changes in density and surface tension for the oxidized and unoxidized cases induced by magnesium (up to 8 wt%) are also presented and compared to previous data.

... SiC_p/Al复合材料的无压浸渗还与以下几个方面的因素有关: (1) 基体中的Mg降低了铝合金熔体的表面张力^[13], 有利于提高其润湿性 ...