Abstract
The corrosion of steel materials is a globally prevalent common issue.The tremendous economic,safety,and environmental hazards the corrosion has caused continue to drive innovation and development of advanced anti-corrosion materials and technologies.Sherardizing technology is an anti-corrosion process of preparing zinc alloy diffusion layers on steel surfaces based on the principles of chemical vapor deposition and atomic thermal diffusion.It offers advantages such as excellent corrosion resistance,high bonding strength,a hydrogen embrittlement-free process,suitability for complex-shaped components,and environmental friendliness.Consequently,it has gained significant popularity in the field of steel corrosion protection and is widely applied in industries such as automotive,shipbuilding,construction,tunneling,railways,water conservancy,and wind energy.Therefore,the work aims to focus on the study of five aspects,including technological evolution,pre-treatment,alloying,post-treatment,and mechanisms,to review the recent research progress of sherardizing technology in China and abroad.
Firstly,the evolution process of sherardizing preparation technology was introduced.The basic principles,main characteristics,and technical advantages of pack cementation,mechanical energy-assisted sherardizing,and vacuum sherardizing were analyzed.Then,special emphasis was placed on elucidating the effects of substrate and main agent nano-modification,multicomponent co-cementation,and rare earth activation on the diffusion of active atoms,microstructure,and properties of the sherardized coatings.The relationship between sherardizing parameters and coating thickness was systematically examined.The strengthening effects of composite post-treatment technologies on the corrosion resistance of cementation coatings were summarized.The formation mechanisms of typical multicomponent co-cementation coatings were analyzed.Finally,the challenges faced by the sherardizing technology for steel surfaces were presented,along with future development directions.This review aimed to provide references for preparing high-performance sherardized coatings and promoting technological innovation and application of sherardizing.
In terms of pre-treatment,the substrate surface nanocrystallization technology could effectively reduce the zinc diffusion temperature,shorten the diffusion cycle,and simultaneously improve the atomic penetration depth,thickness,surface hardness,and corrosion resistance of the sherardized coatings.Regarding alloying,researchers focused on penetrant formulations and rare earth activation.By leveraging the complementary advantages and synergistic effects of various elements,high-corrosion-resistance metal elements such as Al,Ni,Cr,Mg,Cu,Mn,and Ti were introduced to prepare binary or even ternary zinc-based alloy sherardized coatings,significantly enhancing comprehensive properties such as wear and corrosion resistance.Based on the high activity of rare earth elements like Y,Ce,and La,the activation energy for sherardized coating formation was reduced,while their grain boundary pinning and microstructure regulation effects were utilized to achieve synergistic improvement in wear and corrosion resistance of the sherardized coatings.For post-treatment,technologies such as"passivation+organic sealing"and composite coating were employed,relying on physical shielding,electrochemical corrosion resistance,and passivation effects,to elevate the corrosion resistance of the sherardized coatings to over 2000 hours.Concerning the formation mechanism of the sherardized coatings,the formation mechanisms of mono-and binary sherardized coatings were clarified based on the atomic diffusion theory.
In the future,as steel materials face increasingly harsh application environments,higher demands will be placed on the protective performance of sherardized coatings.Sherardizing technology will continue to develop in directions such as multi-component powder diffusion and composite coating post-treatment.Simultaneously,to promote the application of sherardized coatings in extreme environments,research on the environmental adaptability of sherardized coatings should be strengthened.This includes revealing the environmental damage mechanisms of sherardized coatings under typical extreme natural conditions and establishing correlations between laboratory accelerated tests and natural environmental tests.关键词
粉末渗锌技术/多元共渗/合金化/后处理/渗层形成机理Key words
sherardizing technology/multi-element sherardizing/alloying/post-treatment/formation mechanism of sherardized coatings分类
金属材料
