薄膜复合钎料的制备及其在碳化硅陶瓷连接上的应用

发布时间：2018-10-29 21:59

【摘要】：碳化硅(SiC)陶瓷是一种具备良好的高温强度、热导率可达到88W·m~(-1)·K~(-1)、密度仅为3.1～3.2g·cm~(-3)、热膨胀系数低、抗热震性能优异、耐酸碱腐蚀、耐磨损性能极其优越的结构材料,因此广泛应用在航空航天领域、化工领域、核能、微电子和运输等领域。将碳化硅陶瓷制备成大尺寸部件或者是满足特定应用的复杂形状的碳化硅陶瓷部件,在实际的工程应用中可扩展碳化硅陶瓷的应用范围。因此,碳化硅陶瓷新型连接工艺具有重要的研究意义。本论文主要探讨了薄膜复合钎料的制备及其应用在碳化硅陶瓷连接中的连接机理与性能。此外,研究了中间层材料对碳化硅陶瓷与TC4钛合金连接工艺对微观结构以及性能的影响。采用流延成型工艺,制备出含体积分数为10～35%的分别掺SiC陶瓷颗粒、TiC陶瓷颗粒、B4C陶瓷颗粒的Ag-Cu-Ti基的薄膜复合钎料。通过分散剂种类、分散剂含量、粘结剂含量、固含量对浆料流变性能的调节,制备出了浆料流变性能良好,适合流延成型的浆料。最佳配比是选用蓖麻油磷酸酯作为分散剂,蓖麻油磷酸酯的质量分数为5%,粘结剂PVB的质量分数为2.6%,固含量的体积分数为26%。以此配比,流延成型后的薄膜复合钎料具备厚度可控、热膨胀系数可调、陶瓷颗粒均匀分布在Ag-Cu-Ti基体中、具有一定的柔韧性可以随意的裁切成任意形状的特点,有利于后续的碳化硅陶瓷的钎焊连接。采用钎焊连接工艺将制备的薄膜复合钎料用于碳化硅陶瓷连接。研究了添加不同体积分数的陶瓷颗粒的薄膜复合钎料对碳化硅陶瓷连接性能和微观结构的影响。结果发现,薄膜复合钎料在焊温度为900℃、保温时间为10min的条件下都可用来碳化硅陶瓷连接且整个连接界面无裂纹、气孔等缺陷。靠近母材碳化硅附近的反应层产物是TiC相和Ti5Si3相。B4C陶瓷颗粒周围包裹层为TiB2相和TiC相,SiC陶瓷颗粒周围有TiC相和Ti5Si3相,TiC陶瓷颗粒与其他物质不反应。薄膜复合钎料中添加体积分数为20%SiC陶瓷时,其连接件的抗弯强度最高,可达260±19MPa。陶瓷颗粒、母材碳化硅陶瓷附近反应层厚度、陶瓷颗粒周围界面反应是影响连接强度的主要因素。以热膨胀系数介于碳化硅陶瓷与TC4钛合金的金属Ta、Nb、W以及弹性模量较小的Cu为中间层连接碳化硅陶瓷与TC4钛合金。采用Cu作为中间层实现了二者的连接,连接温度、保温时间对连接接头的影响。结合微观结构与力学性能,得出了反应层厚度与扩散层厚度是影响连接强度的最主要原因。在钎焊温度为860℃时、保温时间为20min时,连接部件的抗弯强度达到最大为149.6MPa。连接部件经500℃的10次淬火后,强度降到14±6MPa。主要原因是热震过程中间层Cu氧化失去原有的塑性形变,因此难以缓解连接接头处的热应力。
[Abstract]:Silicon carbide (SiC) ceramics have good high temperature strength. The thermal conductivity can reach 88W m ~ (-1) K ~ (-1), the density is only 3.1g cm~ (-3), the coefficient of thermal expansion is low, and the thermal shock resistance is excellent. It is widely used in the fields of aerospace, chemical industry, nuclear energy, microelectronics, transportation and so on. Silicon carbide ceramics can be made into large size parts or silicon carbide ceramic parts with complex shapes which can be used for specific applications. The application scope of silicon carbide ceramics can be expanded in practical engineering applications. Therefore, it is of great significance to study the new bonding process of silicon carbide ceramics. In this paper, the preparation of thin film composite solder and its application in the bonding of silicon carbide ceramics are discussed. In addition, the effect of interlayer material on microstructure and properties of silicon carbide ceramics and TC4 titanium alloy was studied. The thin film brazing filler metals containing 1035% SiC ceramic particles, TiC ceramic particles and B4C ceramic particles were prepared by the casting process. By adjusting the content of dispersant, dispersant content, binder content and solid content to the rheological properties of slurry, the slurry with good rheological property was prepared and suitable for casting. The best proportion is castor oil phosphate as dispersant, the mass fraction of castor oil phosphate is 5, the mass fraction of binder PVB is 2.6, the volume fraction of solid content is 26. With this ratio, the film composite solder after casting has the characteristics of controllable thickness, adjustable coefficient of thermal expansion, uniform distribution of ceramic particles in the Ag-Cu-Ti matrix, and a certain flexibility that can be cut into arbitrary shape at will. It is advantageous to the brazing bonding of the subsequent sic ceramics. The thin film composite brazing filler metal was used for bonding silicon carbide ceramic by brazing process. The effect of thin film brazing filler metal with different volume fraction of ceramic particles on the bonding properties and microstructure of sic ceramics was studied. The results show that when the welding temperature is 900 鈩，

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