Equipment for Development of a Novel Integrated Laser-Assisted Cold Deposition System

冷喷涂是一种在较低温度下进行喷涂的技术。CS和热喷涂工艺之间的主要差异在于粉末速度和惰性气体温度。CS工艺中超音速颗粒的高冲击产生局部有利的压缩残余应力，其中低气体温度最小化或消除氧化、蒸发、熔化和气体释放。然而，固态结合机制限制了喷涂材料进入韧性材料的范围，降低了结合剂的结构强度并使喷涂材料硬化。此外，产生超音速所需的氦气的高成本限制了CS应用。另一方面，具有较低操作成本的激光熔覆允许涂覆/熔覆更广泛的材料，包括钛、工具钢和铝合金。然而，基于热的激光熔覆工艺会产生有害的残余应力、凝固收缩和不需要的金属间相。在拟议的研究中，所要求的CS基础设施将与现有的光纤激光器和定位设备集成到一个单一的新型激光辅助冷沉积系统，其工作温度范围低于熔化温度，高于传统的CS。这种系统将通过在CS中使用氮气或氩气来消除高操作成本，保持用于沉积的亚熔化温度以克服与熔合相关的缺陷，通过激光辅助结合提供比CS更强的结合，并且允许在增强的温度范围内沉积更硬的材料。所要求的基础设施也将被用作传统的CS系统，以开发一种新的技术来稳定和控制涂层钢激光搭接焊中的汽化和孔隙形成。在结合面区域涂覆一层高熔点材料的薄层CS，可提高加入涂层材料所产生的液态合金的沸点，从而降低涂层材料的汽化。该集成系统为增材制造、结构耐久性和材料连接领域的新研究方向创造了独特的机会，并为许多工业应用带来了好处。

Cold spray (CS) is a promising coating technology at relatively low temperatures. The main differences between the CS and thermal spray processes are in powder velocity and inert gas temperature. The high impact of supersonic particles in the CS process generates local favorable compressive residual stresses where low gas temperature minimizes or eliminates oxidation, evaporation, melting and gas release. However, the solid state bonding mechanism limits the range of spraying materials into ductile material, reduces the structural strength of the bond and hardens the sprayed material. In addition, high cost of helium gas required for generating supersonic velocity limits CS applications. On the other hand, laser cladding with lower operational cost allow for coating/cladding of a much wider range of materials including titanium, tool steels, and aluminum alloys. However, the thermal-based process of laser cladding generates detrimental residual stress, solidification shrinkage, and unwanted intermetallic phases. In the proposed research, the requested CS infrastructure will be integrated with the existing fiber laser and positioning devices to a single novel laser-assisted cold deposition system with working temperature range lower than melting temperature and higher than the conventional CS. This one of a kind system will remove high operational cost by using nitrogen or argon in CS, maintains sub-melting temperature for deposition to overcome fusion related deficiencies, provide stronger bonds than CS through laser-assisted bonding, and allows harder materials to be deposited at the enhanced temperature range. The requested infrastructure will also be utilized as a conventional CS system to develop a novel technique to stabilize and control vaporization and porosity formation in laser lap welding of coated steels. CS coating of thin layer of material with high melting temperature to the faying surface region will increase the boiling point of the liquid alloy produced by added and coat material thus lowering the coat material vaporization. The integrated system creates a unique opportunity to enable new research direction in additive manufacturing, structural durability, and material joining with benefits to many industrial applications.