Advanced alloy surface modification using ultrasonic pulsed waterjets

金属合金表面改性是提高其疲劳、耐磨、耐腐蚀等性能的重要手段。传统上，这可以通过喷丸或喷砂来实现，而现在也可以使用激光冲击喷丸技术。最近，VLN Advanced Technologies（渥太华，ON）开发了一种新的超声脉冲水射流制造技术。该方法允许精确的金属切割和表面涂层的受控去除（例如，硬铬电镀）。然而，也已经证明，表面喷丸是可能的，水射流技术比传统的喷丸更环保，物理上更清洁。拟议的研究，与VLN和GKN烧结金属（圣托马斯，ON）合作，将调查超声水射流喷丸过程中的基本物理机制，特别是在潜在的空化现象，以及相关的材料相互作用。水射流喷丸的效果将被研究用于各种铝，铁和钛合金，使用粉末冶金或增材制造，并与传统的锻造合金变体进行比较。这些材料对加拿大的航空航天和汽车工业非常重要。喷丸后产生的残余表面应力的程度和深度将通过X射线衍射进行量化，并对各种物理和化学性能的影响进行研究。将使用几种轮廓测量和显微镜技术进行表面表征。将评估喷丸前后的疲劳反应。将研究喷丸材料的磨损和腐蚀响应，因为两者对冶金表面条件敏感，这将受到喷丸处理的强烈影响。还将使用差示扫描量热法和电子背散射衍射评估重结晶响应。这个多学科项目的成功完成将为该技术提供科学和工程验证，并为VLN和GKN提供国际竞争优势。

Surface modification of metallic alloys is an important method for improving properties such as fatigue, wear resistance, and even the corrosion susceptibility. Traditionally, this can be achieved by shot peening or grit blasting, while laser shock peening techniques are also now available. Recently, a novel ultrasonic pulsed waterjet manufacturing technique has been developed by VLN Advanced Technologies (Ottawa, ON). This method allows precision metal cutting and controlled removal of surface coatings (e.g., hard chromium plating). However, it has also been demonstrated that surface peening may be possible, with the waterjet technique being much more environmentally friendly, and physically cleaner, than conventional shot peening. The proposed research, in collaboration with both VLN and GKN Sinter Metals (St. Thomas, ON), will investigate the fundamental physical mechanisms operating during ultrasonic waterjet peening, particularly in terms of potential cavitation phenomena, and the associated materials interactions. The effects of waterjet peening will be investigated for various aluminium, iron and titanium alloys, fabricated using either powder metallurgy or additive manufacturing, and compared to conventional wrought alloy variants. These materials are of great importance to the aerospace and automotive industries within Canada. The degree and depth of residual surface stress generated following peening will be quantified through X-ray diffraction, and the effects on a variety of physical and chemical properties will be investigated. Surface characterisation will be conducted using several profilometry and microscopy techniques. The pre- and post-peened fatigue response will be assessed. The wear and corrosion response of the peened materials will be investigated, as both are sensitive to the metallurgical surface condition, which will be strongly affected through peening treatments. The recrystallization response will also be assessed, using differential scanning calorimetry and electron back scatter diffraction. Successful completion of this multi-disciplinary project will provide a scientific and engineering validation of the technique, and an international competitive advantage for both VLN and GKN.