论文部分内容阅读
基于双脉冲电沉积技术在活性钛基(TA2)表面制备纳米晶Ni镀层。通过涂层附着力测试对比研究HF体系和DMF改良型活化液对TA2基体与表面镀层界面结合力的影响;借助TEM、FESEM和XRD等表征技术探讨添加纳米CeO_2粒子前后对纳米电沉积层中Ni晶织构生长的影响;通过对纳米压痕及不同载荷下“十字交叉”型环形硬度压痕特征观察,分析复合CeO_2粒子对Ni镀层表面强韧性的影响机制;进一步探讨在高速干摩擦条件下复合CeO_2粒子对Ni镀层抗磨损的作用。结果表明:在45+80 k Hz交变频率超声振荡条件下,电解液中的活性CeO_2粒子能有效吸附在优先生长Ni晶尖端,同时降低了Ni晶生长Gibbs自由能,并演变为Ni晶的催化形核中心来诱发异质形核;纳米压痕测试表明:在500 g高载荷测试条件下,相对于纯Ni镀层试样的硬度压痕边缘的明显开裂和外拓迹象,Ni-CeO_2复合镀层试样则表现为收敛性和连续完整的压痕边缘特征,显示出良好的强韧性。基于干摩擦过程中释放出大量的热,促使部分稀土CeO_2相弥散或少量析出Ce溶质原子,具有对滑移的位错和晶界等缺陷产生钉扎拖拽作用,由此建立以Orowan位错绕过强化和位错塞积的机制模型;干摩擦过程促使部分富Ce磨损产物与Ni O氧化膜机械混合来充当固体润滑剂,能起到良好的减摩作用,弥补了Ti表面耐磨性差等缺陷。
Preparation of Nanocrystalline Ni Coating on Active Titanium Base (TA2) Surface by Dual Pulse Electrodeposition Technique. The influence of HF system and DMF modified activating solution on the interfacial bonding between TA2 matrix and surface coating was investigated by coating adhesion test. The effects of HF and DMF on the surface adhesion of nano-electrodeposited NiO films were investigated by TEM, FESEM and XRD. The effect of composite CeO 2 particles on the surface toughness of Ni coating was analyzed by observing the indentation features of the “cross” type ring under nano-indentation and different loads. Effect of Composite CeO_2 Particles on Wear Resistance of Ni Coating. The results show that under the condition of 45 + 80 k Hz alternating-frequency ultrasonic oscillation, the active CeO 2 particles in the electrolyte can be effectively adsorbed on the preferentially growing Ni crystal tip, and the Gibbs free energy of the Ni crystal is reduced, Catalytic nucleation center to induce heterogeneous nucleation; nanoindentation test showed that: under 500g high load test conditions, relative to pure Ni coating samples hardness indentation edge obvious cracking and external extension of the evidence, Ni-CeO 2 composite The coated samples showed astringency and continuous complete indentation edge characteristics, showing good toughness. Based on the fact that a large amount of heat is released during the dry friction process, a small amount of Ce solute atoms are precipitated or precipitated in part of the rare earth CeO 2 phase, which has the effect of pinning and dragging the sliding dislocations and the grain boundary defects. Thus, Orowan dislocations Bypassing the mechanism model of strengthening and dislocation plugging; the dry friction process causes some of the Ce-rich wear products to mechanically mix with the NiO oxide film to act as a solid lubricant, which can provide a good anti-friction effect and compensate for the poor wear resistance of the Ti surface Other defects.