等离子喷涂陶瓷-Fe基非晶梯度复合涂层的研究

Atomobile emmissions are regarded as the main source of pollution, so a primary solution is the use of ligh magnesium alloys with high specific stiffness and high specific strength to replace of steel materials. However, Mg alloy is a kind of material with active chamical property, low corrossion resistance and low wear resistance, which restrict its applications. Therefore, many researchs focus on improving the corrossion-resistance and wear-resistance properties. Based on the haracteristics of ceramic materials and metallic glasses, superior wettability between ceramic materials and metallic glasses and the presence of reversible supercooled melt characteristics in metallic glass, the application proposes that one kind of ceramic-Fe based metallic glassy gradient composite coatings is fabricated on Mg alloy by plasma spraying with separated tunnel and post-heating treatment. In this study, the process parameters and the wettability properties between ceramic and metallic glass will be studied. The mechanisms of Fe-based metallic glass toughened ceramic materials and the ceramic strengthened Fe-based metallic glass are going to be investigated. Meanwhile, the corrosion and wear mechanisms of ceramic-Fe based metallic glassy gradient composite coatings will be revealed. The success of the project will imporve the corrossion-resistance and wear-resistance properties of Mg alloy to reach or exceed the level of steel materials, and will establish a theoretical foundation for taking full advantage of the abundant magnesium resources in our country to developt energy-saving and environmental-frinedly materials.

汽车排放是空气污染主要源泉，而采用高比刚度、高比强度的轻型镁合金取代钢铁材料是减少汽车排放的重要途径。而镁合金取代钢铁材料的瓶颈在于镁合金高的化学活性，低的耐腐蚀、耐磨性。因此提高镁合金表面耐磨、耐蚀的研究是国内外研究的热点。依据陶瓷与金属非晶材料性能互补、两者的润湿性优于陶瓷与晶态金属、金属玻璃存在可逆的过冷熔体的特点，采用多路异位送粉等离子喷涂+后续处理的方法，在Mg合金表面制备成分可控的陶瓷（Al2O3或ZrO2等陶瓷）-Fe基金属玻璃梯度复合涂层。研究梯度复合涂层的制备工艺；研究Fe基非晶与陶瓷的润湿机理及影响因素,寻求金属非晶与陶瓷的润湿规律；研究梯度复合涂层中Fe基非晶韧化陶瓷相及陶瓷相强化Fe基非晶的机理；揭示陶瓷-Fe基非晶梯度复合涂层的磨损、腐蚀机制。使Mg合金表面的耐磨、耐蚀性能达到甚至超过钢铁材料的水平。为充分利用我国丰富的Mg资源开发节能、环保绿色材料奠定理论基础

与常规多晶金属材料相比，非晶态合金（亦称金属玻璃）呈现长程无序、短程有序的结构特性，具有许多优异的力学和物理性能，如：高强度、耐腐蚀、耐磨性、良好的磁性能等，具有巨大的潜在应用前景。Fe基非晶更是由于其价格低廉成为国内外科学领域研究和关注的重要课题之一。然而，由于尺寸的限制，非晶合金的产品主要为薄带、细丝、粉末等，难以作为结构材料得以应用。.等离子喷涂是一种材料表面强化和表面改性的技术，可以制备具有耐磨、耐蚀、耐高温氧化及良好结合强度的涂层。而将非晶合金与表面涂层制备技术相结合，即采用现代先进喷涂技术制备大面积厚度可控的非晶涂层，可突破非晶合金尺寸上的限制。将非晶合金作为涂层材料，应用于材料表面技术领域，起到防护作用，或形成特种物理化学性能，拓展非晶材料的应用范围。.但是，作为耐磨材料而言，其韧性问题（即抵抗裂纹扩展能力较差，一旦有微裂纹形成便迅速扩展导致涂层剥落）就成为非晶涂层应用的一个制约条件。采用添加第二相来改善非晶韧性是块体非晶常用的手段。如采用外加难熔金属或陶瓷颗粒促进剪切带增殖来提高其塑性；或如通过成分设计和控制合金熔体凝固产生内生晶体相来改善非晶塑性。因此，实现添加第二相成分比例可控且能均匀分布于基体，对提高非晶涂层的耐磨性具有重要意义。.本项目开发了等离子多路异位送粉喷涂技术，得到成分、比例可调控的陶瓷-非晶复合涂层的制备工艺。系统研究了复合涂层中两相比例对涂层孔隙率、结合强度、硬度性能的影响；分析了涂层的磨损性能及磨损机制；系统地研究了涂层的耐蚀性能及腐蚀机制。研究结果表明当非晶基体中添加20%的陶瓷后，复合涂层的硬度值较单一的非晶涂层提高18.2%，较单一的ZrO2陶瓷涂层提高69.4%。当复合涂层中非晶与陶瓷的比例为4：1时，复合涂层的磨损失重量较单一的非晶涂层降低了66.7%，较单一的ZrO2陶瓷涂层降低了84.7%。并以此作为依据优化了涂层的耐磨、耐蚀成分，制备高耐磨耐蚀的梯度复合涂层。