钛合金层板喷注器扩散焊组织性能调控/变形机理及焊缝无损检测评价

The platelet injector has been started to be used in many types of domestic weapons. However, the existing bonding methods are difficult to meet the requirements of the new model development in the control of microstructure and mechanical properties. In addition, the deformation mechanism of the multi-shaped hole sheet structure and non-destructive detection technology remain uncertain. These have become a bottleneck to limit the development of new engine models. Therefore, this project focuses on the requirements of the diffusion bonding of titanium platelet injectors. The basis of diffusion bonding of titanium alloy will be systematically studied in order to reveal the mechanism of microstructure and mechanical properties control/ deformation of joints and solve the non-destructive detection problems. The project is proposed to study the methods and the mechanism of low-temperature diffusion bonding of titanium alloy. It will also clarify the typical defect characteristics and microstructure evolution mechanism. The relationship between the interface structure and the bonding property will be revealed. We will analyze the deformation mechanism of shaped holes and channels in the diffusion bonding process and the response characteristics of dynamic deformation under the coupling conditions. Therefore, the effective control of interface microstructure and joint performance will be achieved. And the non-destructive detection of micro-scale defects will be completed. Thus, we will ultimately realize high-quality diffusion bonding of titanium platelet injectors and this will provide core basic theories and key technical support for the development of the new space engine models.

层板喷注器在我国多种型号武器上已经开始使用，但是现有连接方法在组织性能调控方面难以满足新型号研制的要求，且多型孔薄板结构变形机理与无损检测技术尚不明确，已成为限制新型号发动机开发的瓶颈技术。本项目针对钛合金层板喷注器的扩散连接需求，以全面揭示接头组织性能调控/变形机理和解决无损检测难题为基本出发点，系统研究钛合金扩散连接的基础问题。拟重点研究钛合金的低温扩散连接方法与机理，阐明接头的典型缺陷特征与组织演化规律，揭示界面结构与连接性能的对应关系，分析型孔与流道在扩散连接过程的变形机理，确定耦合条件下的动态形变响应特性，实现界面组织结构与接头性能的有效调控，完成扩散连接微尺度缺陷的无损检测，最终实现钛合金层板喷注器的高质量扩散连接，为新型号航天发动机的研制提供核心的基础理论和关键技术支持。

喷注器是液体火箭发动机燃烧室的核心部件，由多层具有精密型孔的薄板组成，钎焊可能导致微孔堵塞而无法应用，扩散焊接是唯一可行的方法。扩散焊接中，往往需要通过提高焊接温度来保证接头的连接质量，但过高的温度会导致接头发生过大的塑性变形，降低了接头的精度，因此需要开发低温扩散焊接方法在较低的温度下实现钛合金的可靠连接。本项目以开发新型低温扩散焊接方法为切入点，揭示了表面离子清洗对钛合金扩散焊接接头的影响规律，发现当扩散焊接温度降低至710℃时，未经表面离子清洗的样品无法实现连接，而经过离子清洗后，在此温度下可以成功的实现钛合金的连接。研究了置氢对钛合金表面形貌与力学性能的影响，开发了置氢锆中间层，实现了钛合金的低温扩散焊接，发现随着中间层氢含量的增加，界面处扩散层的厚度和接头的抗剪强度均有所提高，接头最高抗剪强度为180MPa，制备了置氢Nb中间层，实现了TiAl与Ti2AlNb的低温扩散焊接，发现中间层置氢可有效提升接头的抗剪强度，阐明了表面机械研磨实现钛合金表面纳米化的机理，揭示了表面纳米化对扩散焊接界面行为的影响机制，开发了具有自主知识产权的通过表面纳米化实现钛合金低温扩散焊接的方法，发现表面纳米化可将钛合金的扩散焊接温度降低100℃，并利用该方法实现了层板喷注器产品的扩散焊接。建立了层板喷注器扩散焊接有限元模型，揭示了扩散焊接工艺参数对层板厚度与型孔半径变化的影响规律，发现随着焊接温度降低，焊后层板厚度、型孔半径与型孔位置的变化均相应减少，温度降低100 °C，型孔变形量可减少1.05%，利用超声C扫描实现了双层以及三层钛合金层板界面的缺陷无损检测，并提出了采用非线性超声实现界面弱结合检测的方法。