Nucleation bubble boundary layer theory for ultra-fast electrochemical polishing of additive manufacturing components

Du, Jianhua; Liu, Bowen; Zhao, Yonghua

2024-07-25

10.1016/j.addma.2024.104362

ADDITIVE MANUFACTURING   影响因子和分区

2214-8604

2214-7810

The application of electrochemical-based polishing techniques, including electrochemical polishing (ECP) and plasma electrolytic polishing (PEP), to improve the surface quality of additive manufacturing (AM) components is challenged by the high amplitudes and long spatial wavelengths of roughness, which cause pre-polishing procedures to be indispensable. In this study, a nucleation bubble boundary layer (NBBL) mechanism for enhanced electrochemical-based polishing performance is revealed to solve this problem, namely nucleation bubble electrochemical polishing (NBEP). The NBBL is constructed on the anode surface via electrolytic oxygen evolution and nucleate boiling, and is activated by regulating the temperature and electric potential. The experiments verify a model of NBBL consisting of an inner adherent layer and outer diffusion layer (ODL). Simulations and experiments demonstrate that the polishing mechanism is based on the combined current-limiting effect of individual adherent bubbles and the ODL, which differentiates the anodic dissolution rates at the peaks and valleys of a wide range of spatial wavelengths with their electrical resistance. The bubble dynamics also enhance mass transfer, further improving the polishing efficiency. The experimental results show that NBEP is capable of reducing the surface roughness of AM stainless steel 316 L from Ra of 10.22 mu m to 0.71 mu m, and eliminating the spatial wavelengths of 200-400 mu m in 8 min, which cannot be achieved by either ECP or PEP. The polishing current density also increased from 0.25 (ECP) and 0.48 (PEP) to 2 A/cm(2) in NBEP. Finally, a prediction model that accurately describes the ultimate roughness achieved by NBEP as a function of the minimum cavity size is established. The NBEP can be directly followed by PEP or ECP to achieve an optimal surface finish of Ra <70 nm for AM parts. The NBEP method considerably enhances the polishing performance of electrochemical-based systems for AM components, as well as expands the application range of electrochemical-based polishing techniques.

Electrochemical polishing Surface boundary layer Nucleate boiling Oxygen evolution Bubble dynamics

SCI ; EI

英语

第一 ; 通讯

Research Foundation[2024A1515010441] ; Guangdong Provincial University Science and Technology Program[2023ZDZX2023] ; Shenzhen Science and Technology Program[KQTD20170810110250357]

Engineering ; Materials Science

Engineering, Manufacturing ; Materials Science, Multidisciplinary

WOS:001301012000001

ELSEVIER

Web of Science

Southern Univ Sci & Technol, Dept Mech & Energy Engn, Shenzhen 518055, Peoples R China

Du, Jianhua,Liu, Bowen,Zhao, Yonghua. Nucleation bubble boundary layer theory for ultra-fast electrochemical polishing of additive manufacturing components[J]. ADDITIVE MANUFACTURING,2024,92.

Du, Jianhua,Liu, Bowen,&Zhao, Yonghua.(2024).Nucleation bubble boundary layer theory for ultra-fast electrochemical polishing of additive manufacturing components.ADDITIVE MANUFACTURING,92.

Du, Jianhua,et al."Nucleation bubble boundary layer theory for ultra-fast electrochemical polishing of additive manufacturing components".ADDITIVE MANUFACTURING 92(2024).