氢气流量对超音速微粒沉积Al­12Si涂层的影响

摘要

采用 SEM、XRD、EDS、拉伸试验机及硬度仪，检测不同氢气流量下采用超音速微粒沉积技术制备的Al­12Si 涂层形貌、相组成和力学性能，研究作为次燃料气和还原气的氢气流量对涂层结构和性能的影响。结果表明：提高氢气流量能显著提高颗粒的速度，利于颗粒沉积；氢气流量为30 L/min时涂层最厚，但孔隙率最大；继续增大氢气流量，厚度减小，孔隙率降低；涂层由α(Al)相和Al­Si共晶相组成，氧含量随氢气流量增大而降低，未发现氧化物相；涂层结合强度超过34 MPa，硬度是基体硬度的2倍以上，结合强度和硬度均随氢气流量增大而增大，能够显著提升基体的耐磨性能。%Adopting scanning electron microscopy (SEM), X­ray diffraction (XRD), energy dispersive spectrometer (EDS) and tensile machine and hardness tester, the morphologies, phase constitutions and mechanical properties of Al­12Si coatings by supersonic particles deposition (SPD) at different hydrogen flow rates were detected, and the effect of the flow rate of hydrogen, which was treated as minor­fuel and reductive gas in the process of coating, on the structure and properties was studied. The results demonstrate that increasing the hydrogen flow rate can increase the velocity and deposition rate of the particles remarkably. The coating reaches the largest thickness and porosity when the hydrogen flow rate is 30 L/min, and the thickness and porosity tend to decrease with increasing hydrogen flow rate. The coating is composed of α(Al) phase and Al­Si eutectic phase, and the content of oxygen decreases with increasing the hydrogen flow rate, but oxidation phase is not discovered. The bonding strength is beyond 34 MPa, and the hardness of coating is twice more of substrate. The bonding strength and hardness increase with increasing the hydrogen flow rate, which can enhance the wear resistance of substrate notably.