Cold spray: effect of mixing powders

冷喷涂：混合粉末的效果

• 批准号: RGPIN-2017-05242
• 负责人: Yue, Stephen
• 金额: $ 3.42万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=689447
• 关键词: Cold; spray; effect; mixing; powders

Cold spray is a seemingly simple method to apply metal coatings to metal, ceramic and polymer surfaces by accelerating metal powders of about 20 to 40 micron particle diameter to supersonic speeds using a carrier gas, usually nitrogen. On impact with the substrate to be coated, the particles severely plastically deform and instantaneously bond to the substrate and each other. The coating of the substrate takes place in air at room temperature. The usual methods to bond powder particles are performed at very high temperatures, between about 80% of the melting point and even upto the melting point, and require very long times, at least a few hours. Clearly the short times and the fact that coatings are done in air are obviously advantageous; room temperature processing means that heat damage is avoided and also means that unlikely materials pairings are possible, such as polymers embedded in a metal matrix. Moreover, very thick 3D coatings can be made, thus elevating the process to one of additive manufacturing.***Usually, only one metal powder is sprayed, but this proposal is concerned with what happens when a mixture of powders is cold sprayed. As noted above, interesting composites' can be made by cold spray and part of this work concerns making composites for various applications: metal metal composites for biodegradable stents, metal coatings for lightning strike protection for aircraft structures made of carbon fibre reinforced polymer composites and metal matrix-tungsten carbide composites for wear resistant coatings. The scientific objective, however, is to understand what happens to the cold spray process when mixed powders are sprayed. In this respect we are mainly concerned with the cold sprayability of the mixtures, or how easy it is for these powders to bond onto the substrate to form a thick coating. Cold sprayability is usually judged by the deposition efficiency, i.e. how much of the sprayed powder sticks, and the level of porosity in the coating, the lower the porosity, the better the coating as a general rule. Previous work by our team has shown that the mixing can significantly affect cold sprayability, but in a very unpredictable manner, belying the simplicity of the cold spray concept. This work aims to understand the cold spray mechanisms associated with powder mixing, and use this to develop accurate predictions of cold sprayability. ***Cold spray is rapidly becoming a key repair' method and, as such, adds to the capacity of technologies for sustainability. As mentioned above, it is one of the additive manufacturing technologies and is therefore of interest to the automotive and aerospace industries. This program is scientifically intriguing and is of great contemporary engineering importance. It represents an excellent training opportunity to generate high quality personnel in the advanced manufacturing sector a vital contributor to the Canadian economy.

冷喷雾是一种看似简单的方法，将金属涂料涂在金属，陶瓷和聚合物表面上，通过将约20至40微米颗粒直径的金属粉末加速使用，使用载气，通常是氮气。 在与要覆盖的基板的影响下，颗粒会严重变形，并瞬时键与底物和彼此键合。 基板的涂层在室温下在空气中进行。 通常在非常高的温度下，约80％的熔点甚至到熔点，需要很长时间，至少需要几个小时，就可以在非常高的温度下进行键合粉末颗粒的通常方法。 显然，短时间和在空气中完成涂料的事实显然是有利的。室温加工意味着避免热损伤，也意味着不太可能的材料配对，例如嵌入金属基质中的聚合物。 此外，可以制作非常厚的3D涂层，从而将过程提升到添加剂制造之一。 如上所述，有趣的复合材料可以通过冷喷雾制成，其中一部分工作涉及为各种应用制造复合材料：用于可生物降解的支架的金属金属复合材料，用于针对由碳纤维增强聚合物制成的飞机结构的金属涂料保护，由碳纤维增强的聚合物复合材料和金属Matrix-Tungsten碳化物碳化物材料用于佩戴耐磨性涂层。 但是，科学的目标是了解喷涂混合粉末时冷喷雾过程会发生什么。 在这方面，我们主要与混合物的冷喷涂性有关，或者这些粉末将粘合到基板形成厚涂层的容易性。 冷喷涂性通常是通过沉积效率来判断的，即多少喷粉棒和涂料中的孔隙率水平，孔隙率越低，涂层越好。 我们的团队以前的工作表明，混合可以显着影响冷喷涂性，但以非常不可预测的方式，表达了冷喷雾概念的简单性。 这项工作旨在了解与粉末混合有关的冷喷雾机制，并使用它来制定冷喷涂性的准确预测。 ***寒冷喷雾正迅速成为一种关键的修复方法，因此增加了可持续性技术的能力。 如上所述，它是增材制造技术之一，因此是汽车和航空航天行业感兴趣的。 该计划在科学上很有趣，并且具有当代工程的重要性。 它代表了在高级制造业中产生高质量人员的绝佳培训机会，这是加拿大经济的重要贡献。