In this study, the characteristics of film formation and the difference in corrosion resistance between AZ91D Mg alloy and SEN (Stainless Environment -friendly Nonflammable) Mg alloy was investigated after the Plasma Electrolytic Oxidation (PEO) surface treatment. In order to create the early applic...
In this study, the characteristics of film formation and the difference in corrosion resistance between AZ91D Mg alloy and SEN (Stainless Environment -friendly Nonflammable) Mg alloy was investigated after the Plasma Electrolytic Oxidation (PEO) surface treatment. In order to create the early application market for SEN Mg alloy which was commercialized in 2015 through domestic development, an onsite research based on empirical and commercially similar condition is necessary. Die casting and chemical reagent, experimental apparatus of pervious experiments were not used at all, but only industrial chemicals and facility currently available onsite were used from gravitational casting to wire cutting and PEO treatment.
From the comparison result for AZ91D and SEN Mg alloy (hereinafter, Both Alloys) through SEM, EDS Maps, Point, and Line analysis, SEN Mg alloy has finer structure and higher calcium (Ca) concentration than AZ91D in the grain boundary.
From implementing of the 5/10/30 minutes PEO treatment for both alloys, it was found that there was no substantial difference in the thickness of oxide film. From the result of summarizing the average thickness and individual specimen, the change in the thickness of oxide film was decreased gradually according to PEO treatment time.
In order to observe the formation characteristic of PEO film, the surface was checked by surface SEM image. As the PEO treatment time for both alloys increased from 5 minutes to 10 and 30 minutes, the number of pores in AZ91D decreased, while there was no change in the size of pores. In the case of SEN Mg alloy, not only the number of pores but also the size of pores decreased.
The cross sectional SEM image shows that the film layer became thicker to improve the corrosion resistance as the PEO treatment time was increased from 5 minutes to 10 and 30 minutes. However, it is judged that the treatment requires more than 10 minutes at least. For additional improvement in corrosion resistance, the sealing treatment is needed. In EDS Maps, fluorine (F) was detected in both alloys. It is previously known that the fluorine component improves the conductivity of electrolyte and drops the PEO process voltage, and resultantly contributes to the improvement in the corrosion resistance as it has an effect to reduce the size of pores.
The result of increasing the PEO treatment for two alloys from 5 minutes to 10 and 30 minutes shows the improvement in corrosion resistance as the oxide film of both alloys becomes thicker to protect the base materials. When PEO treatment was implemented for 5 minutes, the number of corrosion point of SEN Mg alloy was higher than that of AZ91D Mg alloy, but the size of corrosion point was smaller. As the time for PEO treatment increased, the corrosion resistance (salt spray test) of SEN alloy was more superior than that of AZ91D Mg alloy.
Accordingly, SEN Mg alloy is not only eco-friendly and non flammable material but also a new Mg alloy of more improved corrosion resistance. It is a great desire for our country's magnesium industry to be a new power source of growth by preoccupying markets through early application of SEN Mg alloy.
In this study, the characteristics of film formation and the difference in corrosion resistance between AZ91D Mg alloy and SEN (Stainless Environment -friendly Nonflammable) Mg alloy was investigated after the Plasma Electrolytic Oxidation (PEO) surface treatment. In order to create the early application market for SEN Mg alloy which was commercialized in 2015 through domestic development, an onsite research based on empirical and commercially similar condition is necessary. Die casting and chemical reagent, experimental apparatus of pervious experiments were not used at all, but only industrial chemicals and facility currently available onsite were used from gravitational casting to wire cutting and PEO treatment.
From the comparison result for AZ91D and SEN Mg alloy (hereinafter, Both Alloys) through SEM, EDS Maps, Point, and Line analysis, SEN Mg alloy has finer structure and higher calcium (Ca) concentration than AZ91D in the grain boundary.
From implementing of the 5/10/30 minutes PEO treatment for both alloys, it was found that there was no substantial difference in the thickness of oxide film. From the result of summarizing the average thickness and individual specimen, the change in the thickness of oxide film was decreased gradually according to PEO treatment time.
In order to observe the formation characteristic of PEO film, the surface was checked by surface SEM image. As the PEO treatment time for both alloys increased from 5 minutes to 10 and 30 minutes, the number of pores in AZ91D decreased, while there was no change in the size of pores. In the case of SEN Mg alloy, not only the number of pores but also the size of pores decreased.
The cross sectional SEM image shows that the film layer became thicker to improve the corrosion resistance as the PEO treatment time was increased from 5 minutes to 10 and 30 minutes. However, it is judged that the treatment requires more than 10 minutes at least. For additional improvement in corrosion resistance, the sealing treatment is needed. In EDS Maps, fluorine (F) was detected in both alloys. It is previously known that the fluorine component improves the conductivity of electrolyte and drops the PEO process voltage, and resultantly contributes to the improvement in the corrosion resistance as it has an effect to reduce the size of pores.
The result of increasing the PEO treatment for two alloys from 5 minutes to 10 and 30 minutes shows the improvement in corrosion resistance as the oxide film of both alloys becomes thicker to protect the base materials. When PEO treatment was implemented for 5 minutes, the number of corrosion point of SEN Mg alloy was higher than that of AZ91D Mg alloy, but the size of corrosion point was smaller. As the time for PEO treatment increased, the corrosion resistance (salt spray test) of SEN alloy was more superior than that of AZ91D Mg alloy.
Accordingly, SEN Mg alloy is not only eco-friendly and non flammable material but also a new Mg alloy of more improved corrosion resistance. It is a great desire for our country's magnesium industry to be a new power source of growth by preoccupying markets through early application of SEN Mg alloy.
주제어
#마그네슘 합금 Mg AZ91D SEN PEO 플라즈마 전해산화 친환경 난연성
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