The Study Of Thermal Diffusion Aluminizing Process On The Surface Of Magnesium Alloy

Magnesium alloys are the lightest structure meta l in the engineering materia ls. It hasbeen widely applied in the filed of automotive industry, electronic industry,communication, aerospace, nationa l defence and military, etal. It can be recycled veryeasily, so it is called"The green engineering materia ls in the 21st century". However, itwould be corroded seriously if on protective measures are carried out ahead, because itselectrode potentia l is very low. We can conclude that the poor corrosion resista nce limitsthe applica tion of ma gnesium alloys seriously. At present, it has become a focus todevelop the technics to improve the corrosion resista nce of ma gnesium alloys.The feasibility of salt bath aluminizing on the surface of ma gnesium alloys wasresearched in this paper. Diffution agent used in our experiments was AlCl3&NaCl(1:1).Influnce of the diffution temperature and time on the salt bath aluminizing diffutioncoatings was also researched. The results showed that: it was possible to improve thecorrosion resista nce of ma gnesium alloy with salt bath aluminizing process under presentconditions; a coating with a best thick ness of 15μm and 50μm formed respectively on thesurface of pure ma nisium and AZ91D ma gnesium; the aluminizing la yer was composedwih intermeta llic compound such as Al12Mg17, Al3Mg2, AlMg; there is 44.5 at% and39.7at% aluminium respectively in the intermeta llic la yer of pure ma nesium and AZ91Dma gnesium; the microha rdness of aluminizing on the AZ91D and pure ma nisium andcoatings was 144.98HV and 136.0HV respectively; the corrosion resista nce of ma gesiumalloys was improved; we got the best process parameters : 350℃&8h with a lot of hardwork.Referenced on the research above, the influnce of surface nano-crysta lliza tion on thethermal diffution of ma gnesium alloys was studied in this paper. Supersonic FineParticles Bombarding (SFPB) was used to obtain grains of nanometer dimension on thesurface of wrought ma gnesium and AZ91D ma gnesium. Salt bath aluminizing process was used to treat the ma gnesium alloys afer SFPB. Results showed that: a la yer withgrains of nanometer dimension could be obtained on the surface of wrought ma gnesiumand AZ91D ma gnesium; however, no significa nt improvement of thick ness ofaluminizing coating and corrosion resista nce could be botained after the salt bathaluminizing on the SFPB ma gnesium alloys.