Investigation of Surface Integrity induced by Cryogenic Processing of Biomaterials for Improved Functional Performance

这项拨款为在严重塑性变形（SPD）过程中对金属生物材料的低温加工产生的表面完整性的定量理解研究提供资金。工程表面层将在选定的生物材料中生产，具有首选的纳米/超细颗粒结构，增加硬度和压缩残余应力等，以改善生物医学植入物和其他制造部件的功能性能。将开发低温加工和抛光工艺，在选定的生物材料中生产具有纳米/超细颗粒结构的表面层，以提供更好的耐磨性和耐腐蚀性，并提供更长的疲劳寿命的压缩残余应力。主要项目任务为：(1)系统实验研究低温加工表面的完整性，确定工艺参数对表面硬度、晶粒尺寸和残余应力的影响；(2)低温加工部件的测试，以量化性能改进，特别是耐腐蚀、耐磨性和疲劳寿命；(3)采用数值和解析方法开发混合预测性能模型；(4)开发性能改进的优化方法；(5)模型验证与细化。如果成功，该项目将为新型低温制造工艺提供预测性能模型，为用生物材料生产功能优越的产品提供最佳工艺参数。通过优化设计和执行低温工艺，提高了耐磨性和耐腐蚀性，延长了疲劳寿命，这是最理想的产品性能指标之一。在某些应用中，通过深冷处理优选出的超硬表面层将有可能取代硬涂层。预期的项目发现也将有潜力在其他制造应用中生产组件，以提高性能和寿命，特别是在航空航天和汽车领域。实施清洁、无毒、不会对健康造成不利影响的低温工艺也可获得重大的健康和环境效益。

This grant provides funding for research on quantitative understanding of the integrity of surfaced produced by cryogenic processing of metallic biomaterials during severe plastic deformation (SPD) processes. Engineered surface layers will be produced in selected biomaterials, with preferred nano/ultrafine grain structures, increased hardness and compressive residual stresses, etc., for improved functional performance in biomedical implants and other manufactured components. Cryogenic machining and burnishing processes will be developed to produce surface layers with nano/ultrafine grain structures in selected biomaterials to provide improved wear and corrosion resistance, and compressive residual stresses to offer greater fatigue life. Major project tasks are: (1) Systematic experimental study of the integrity of surfaced produced by cryogenic processes to establish the influence of processing parameters on hardness, grain size and residual stresses; (2) Testing of cryogenically-processed components to quantify performance improvement, especially corrosion and wear resistance and fatigue life; (3) Development of hybrid predictive performance models using numerical and analytical methods; (4) Development of optimization methods for performance improvement; and (5) Model validation and refinement. If successful, this project will lead to predictive performance models for novel cryogenic manufacturing processes to provide optimal process parameters for producing functionally-superior products from biomaterials. Improved wear and corrosion resistance and enhanced fatigue life are among the most desirable product performance measures expected from optimally designed and performed cryogenic processes. Optimally produced superhard surface layers from cryogenic processing will have the potential to replace hard coating in some applications. The anticipated project findings will also have the potential for producing components in other manufacturing applications for improved performance and life, especially in aerospace and automotive sectors. Significant health and environmental benefits can also be achieved from the implementation of cryogenic processes, which are clean, toxic-free, and pose no adverse health effects.