The sessile drop method combined with a capillary purification procedure was used,for thefirst time,to analyze the high-temperature behavior of molten Mg on three dissimilar substrates:1)molybdenum,2)tantalum and 3)AISI...The sessile drop method combined with a capillary purification procedure was used,for thefirst time,to analyze the high-temperature behavior of molten Mg on three dissimilar substrates:1)molybdenum,2)tantalum and 3)AISI 316L stainless steel.All tests were performed under isothermal conditions at 720℃ in a protective atmosphere(Ar+5 wt.%H2).Images of Mg/substrate couples recorded during the experiments were used to calculate the contact angles(θ)formed between the liquid Mg drop and the selected substrates.After the sessile drop tests,the Mg/Mo,Mg/Ta,and Mg/AISI 316L couples were subjected to in-depth microstructural characterization using scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS).Under the employed experimental conditions,oxide-free Mg drops on all tested couples presented non-wetting behavior(θ>90°).The average values of the calculated contact angles after 40 s of liquid Mg deposition wereθMg/Mo=124°,θMg/Ta=125°,andθMg/AISI 316L=126°,respectively.The SEM/EDS analysis showed no mass transfer and no bonding between solidified drops and the substrates.This non-reactive and non-wetting behavior of investigated couples can be associated with the immiscible nature of the Mg-Mo,Mg-Ta,and Mg-Fe systems,where the solubility of liquid Mg with all tested materials is negligible,and Mg does not form any compounds with them.展开更多
The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)us...The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)using the Capillary Purification(CP)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)procedure.The high-temperature tests were performed under isothermal conditions(CP:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) atmosphere.During the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate couples.Scanning and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθ<90°in<1 s),followed by fast spreading and good wetting over the Ni substrate(θ_((CP))~20°in 5 s)to form a final contact angle ofθ_(f(CP))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.展开更多
文摘The sessile drop method combined with a capillary purification procedure was used,for thefirst time,to analyze the high-temperature behavior of molten Mg on three dissimilar substrates:1)molybdenum,2)tantalum and 3)AISI 316L stainless steel.All tests were performed under isothermal conditions at 720℃ in a protective atmosphere(Ar+5 wt.%H2).Images of Mg/substrate couples recorded during the experiments were used to calculate the contact angles(θ)formed between the liquid Mg drop and the selected substrates.After the sessile drop tests,the Mg/Mo,Mg/Ta,and Mg/AISI 316L couples were subjected to in-depth microstructural characterization using scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS).Under the employed experimental conditions,oxide-free Mg drops on all tested couples presented non-wetting behavior(θ>90°).The average values of the calculated contact angles after 40 s of liquid Mg deposition wereθMg/Mo=124°,θMg/Ta=125°,andθMg/AISI 316L=126°,respectively.The SEM/EDS analysis showed no mass transfer and no bonding between solidified drops and the substrates.This non-reactive and non-wetting behavior of investigated couples can be associated with the immiscible nature of the Mg-Mo,Mg-Ta,and Mg-Fe systems,where the solubility of liquid Mg with all tested materials is negligible,and Mg does not form any compounds with them.
基金supported by the National Science Centre of Poland within OPUS 16 Project,no.2018/31/B/ST8/01172。
文摘The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)using the Capillary Purification(CP)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)procedure.The high-temperature tests were performed under isothermal conditions(CP:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) atmosphere.During the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate couples.Scanning and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθ<90°in<1 s),followed by fast spreading and good wetting over the Ni substrate(θ_((CP))~20°in 5 s)to form a final contact angle ofθ_(f(CP))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.
