Potassium persulfate was used as an effective oxidizer for chemical mechanical polishing (CMP) of GCr15 steel. The effects of pH, potassium persulfate content and chelating agents on the CMP performance of GCr15 steel were investigated, and the surface films formed in the potassium persulfate-based slurries were characterized accordingly. It is revealed experimentally that, with pH increasing from 2.0 to 9.0, the material removal rate (MRR) is independent of pH while the surface roughness R a decreases. At pH 8.0, as the potassium persulfate content increases, the MRR linearly increases with a slope of 48 nm min −1 mM −1 , but the surface quality continues to deteriorate accompanied with the black Fe 3 O 4 residue due to the severe corrosion by persulfate. In particular, Fe 2+ and Fe 3+ ions are continuously produced by oxidation of persulfate, and a significant part of Fe 2+ and Fe 3+ further reacts with OH − to form a non-uniform and rough surface film which primarily consists of Fe 3 O 4 . After adding an appropriate chelating agent EDTA, the R a reaches 1.7 nm without any black residue due to the chelation reactions between iron ions and EDTA. The findings suggest that a nano-precision surface finish of bearing steel could be achieved at weakly alkaline pH with persulfate-based slurries. Graphic abstract
Can Wu,Yingwei Wu,Huijun Zhao,Shuaishuai Li,Jing Ni,Xinglin Li
The surface microstructure of biomimetic Procambarus clarkia claw was prepared on the surface of GCr15 steel, then PTFE solid lubricants dispersed with three different hardness nanoparticles (C, ZnO, Al 2 O 3 ) were filled in. The results of the tribological experiment show the textured surface lubricated by PTFE with Al 2 O 3 nanoparticles reflected the best performances. Because PTFE stored by the bionic texture could be supplied to the friction surface to form a solid lubrication film. Due to the addition of Al 2 O 3 nanoparticles, the hardness and wear resistance of the film are improved, thus avoiding a large loss of PTFE. And the process of "rolling-embedding PTFE surface-exposing-rolling" occurs. As a final, the surface tribological properties of GCr15 steel can be significantly improved.
With the development of deep-sea exploration technology, the technology of fire-retardant hydraulic fluid (HFC) has played an important role in the power transmission of exploration equipment. However, the mechanism of the influence of seawater content on the tribocorrosion behavior of HFC remains unclear. In this study, the effects of different seawater contents on the tribological and corrosive properties of HFC were systematically investigated. The results showed that when the seawater concentration exceeds 30 wt%, a soft Mg-containing reaction film is formed in the friction contact area owing to seawater corrosion, thus effectively improving the sintering load and wear resistance to some extent. By contrast, with increasing seawater concentration, the lubricity declines, the wear intensifies, and the extreme pressure characteristics decrease significantly. The comparative analysis shows that the composition of the wear and corrosion reaction films significantly differs under high-concentration seawater conditions, which is also a key factor affecting the friction and corrosion behavior of HFC. This study provides a direction for the research and development of wear- and corrosion-resistant materials and coatings on the surface of deep-sea exploration equipment.
危险品化学品经营许可证（带存储）