The fundamental equations of thermodynamics of a film have been used for describing a fundamental property of solid crystalline materials i.e. the first-order phase transition on the grain boundaries by the formation ...The fundamental equations of thermodynamics of a film have been used for describing a fundamental property of solid crystalline materials i.e. the first-order phase transition on the grain boundaries by the formation of two-dimensional liquid. The generalized equation that is obtained is used for calculating the premelting temperature of any metal, which has a value in the range of 0.55-0.86 of the melting point. The experimental diffusion coefficient of nitrogen in steel at premelting temperature is the same as in the liquid phase. The described phenomenon of phase transition on the grain boundaries decreases in case of radical modification of the existing process engineering of handling metals. It also provides a precise physical explanation to the super plasticity of fine-structure metal alloys.展开更多
We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and l...We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface.At temperatures above−10℃ or for high enough sliding speeds,a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small.In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities.We comment on the role of waxing on the friction between skis and snow(ice particles).展开更多
The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air an...The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air and water-free argon atmosphere,and then the influencing factors were analyzed.It had been found that the hydrogen content in steel varied with different slag compositions.The compositions and state of slag had significant effect on the hydrogen level in steel.Partial return slag and premelted slag could avoid the hydrogen pick-up especially in the early stages of the process.However,premelted slag was the optimum state to control the hydrogen pick-up in steel.Experimental results indicated that water-free argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.展开更多
文摘The fundamental equations of thermodynamics of a film have been used for describing a fundamental property of solid crystalline materials i.e. the first-order phase transition on the grain boundaries by the formation of two-dimensional liquid. The generalized equation that is obtained is used for calculating the premelting temperature of any metal, which has a value in the range of 0.55-0.86 of the melting point. The experimental diffusion coefficient of nitrogen in steel at premelting temperature is the same as in the liquid phase. The described phenomenon of phase transition on the grain boundaries decreases in case of radical modification of the existing process engineering of handling metals. It also provides a precise physical explanation to the super plasticity of fine-structure metal alloys.
文摘We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface.At temperatures above−10℃ or for high enough sliding speeds,a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small.In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities.We comment on the role of waxing on the friction between skis and snow(ice particles).
文摘The pick-up of hydrogen during electroslag remelting process for several slags consisting of CaF2-Al2O3-CaO-SiO2-MgO had been investigated.The laboratory-scale remelting experiments had been carried out in open air and water-free argon atmosphere,and then the influencing factors were analyzed.It had been found that the hydrogen content in steel varied with different slag compositions.The compositions and state of slag had significant effect on the hydrogen level in steel.Partial return slag and premelted slag could avoid the hydrogen pick-up especially in the early stages of the process.However,premelted slag was the optimum state to control the hydrogen pick-up in steel.Experimental results indicated that water-free argon atmosphere was very favorable to the control of hydrogen in steel in the normal remelting period.
