碳基复合材料表面金属化及界面结合强化机制研究

Carbon-based composites are considered with a wide application prospect in many industry fields due to the excellent properties such as low density and high strength. Reliable joining of the composite to metal parts is the key and difficulty point for full exploitation of the composite properties. The conventional joining techniques are usually with some problems such as thermal stress, low bonding strength and loose contact at the interface, etc. Surface metallization of carbon-based composites offers an alternative solution of the joining problem. In this project the surface metallization will be accomplished through sonoelectrodeposition technique and the interface strengthening mechanism will be systematically studied. Compact contact at the micro-scale may be achieved through electrodeposition process with the introduction of ultrasonic agitation effect and cavitation effect; low-expansion alloy will be chosen as the surface metallization layer in order to avoid thermal expansion mismatch and to reduce the residual stress; moreover, active metal elements such as Ti, Cr or V will be co-deposited near the interface to achieve a coherent and dense reaction layer during the subsequent heat treatment process, for the purpose of bonding strength improvement. Based on the study on the micromorphology of the interface, the microstructure and the distribution of the reaction layer, the interface strengthening mechanism will be revealed and it offers a theoretical and technical reference for the improvement of joining between carbon-based composites and metal parts.

碳基复合材料因其轻质、高强等优异性能而具有广阔的应用前景，与金属的可靠连接是扩大其应用范围的关键和难点。针对常规连接所存在的微观界面结合不紧密、界面热膨胀不匹配以及结合强度低等问题，提出对碳基复合材料进行表面金属化作为连接过渡层的解决思路并拟采用电沉积法实现表面金属化及对界面问题进行系统研究：利用电沉积的工艺特点并引入超声搅拌作用及空化效应，促进电沉积溶液对复合材料表面疏松结构的浸润以及溶质离子的传质过程，以获得微观程度紧密接触的结合界面；选择低膨胀合金体系作为表面金属层，以满足界面热匹配及减小热应力的要求；探讨活性金属元素的共沉积工艺及界面反应机制，通过控制活性元素含量及分布并通过后续热处理以促进界面反应层的生成，实现界面冶金结合。在对界面微观结构形貌、反应机制以及界面热模拟等进行综合研究的基础上，揭示碳基复合材料表面金属化的界面结合强化机制，为与金属连接技术的发展提供技术与理论参考。

碳基复合材料因其轻质、高强等优异性能而具有广阔的应用前景，与金属的可靠连接是扩大其应用范围的关键和难点。针对常规连接所存在的微观界面结合不紧密、界面热膨胀不匹配以及结合强度低等问题，提出对碳基复合材料进行表面金属化作为连接过渡层的解决思路。本项目研究中，将碳材料的表面呈疏松多孔状这一对界面结合不利的因素转化为表面金属化的有利因素，通过表面预处理并利用电沉积的工艺特点并引入超声搅拌作用及空化效应，促进电沉积溶液对基底材料表面疏松结构的浸润以及溶质离子的传质过程，获得了微观程度紧密接触的结合界面；并采用复合电沉积法实现了碳反应活性元素纳米钛颗粒的的共沉积，SEM形貌观察及元素面扫描均表明钛颗粒在镀层中的分布较为均匀，分析了界面反应热力学并通过后续热处理以促进界面相的生成，实现了界面剪切强度的显著提升，优化电沉积工艺的界面剪切强度平均值为16.24MPa，相对于常规电沉积（4.92MPa）有显著的提升；通过活性元素引入及后续热处理生成界面反应相，界面结合强度可进一步提升至17.75MPa。结合界面强度变化及剪切断口形貌等初步揭示了界面强化机制。本项目的研究，无论是在宏观的异质材料连接方面，还是碳增强体与金属的复合界面设计调控方面，都具有一定的参考价值。