Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone d...Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone different periods of vanadizing time at 950 ℃ was measured. These depth values ( x ) and its corresponded time ( t ) were substituded into the experimental formula, i.e., x n=Kt (ln x=(1/n) ln K+(1/n) ln t ), and were processed by mono linear regression. It is found that x and t have the relationship of x 2=Kt . Addition of rare earth can promote reaction of the permeating agent, and increase vanadium potential of the agent. Rare earth, as a strong reductant, makes the oxide on the steel surface reduced, and thus activates the steel surface. Permeating of rare earth into steel and the VC layer intensifies the crystal fault density, and, together with its excellent chemical activation, makes carbon atoms diffuse easily. These functions of rare earth can decrease the diffusion activation energy of the carbon atoms, and therefore has catalytic effect on permeation.展开更多
Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life p...Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life period of Crl2 steel as punching die. Kinetics of vanadium carbide coating growth was brought forward and verified by comparison of the mathematical model with the experimental results. The thickness of coating was illustrated by SEM. The chemical constituent of coating and remnants were tested by X-ray diffraction （XRD） and X-ray energy dispersive spectroscopy （EDS）. To increase the thickness, rare earth silicon powder （FeSiRe23） was added to the borax salt bath. The analysis of XRD revealed that FeSiRe23 increased the depth of vanadium car-bide coating as reducing agent and catalysis.展开更多
文摘Adding rare earth into permeating agent has an obvious catalytic effect on vanadizing on steel surface, and the vanadizing rate can increase about 30%～40%. The case depth ( x ) of the samples which have undergone different periods of vanadizing time at 950 ℃ was measured. These depth values ( x ) and its corresponded time ( t ) were substituded into the experimental formula, i.e., x n=Kt (ln x=(1/n) ln K+(1/n) ln t ), and were processed by mono linear regression. It is found that x and t have the relationship of x 2=Kt . Addition of rare earth can promote reaction of the permeating agent, and increase vanadium potential of the agent. Rare earth, as a strong reductant, makes the oxide on the steel surface reduced, and thus activates the steel surface. Permeating of rare earth into steel and the VC layer intensifies the crystal fault density, and, together with its excellent chemical activation, makes carbon atoms diffuse easily. These functions of rare earth can decrease the diffusion activation energy of the carbon atoms, and therefore has catalytic effect on permeation.
基金Funded by the National Natural Science Foundation of China (No.50675165)the National Key Technology R&D Program (No.2006BAF02A29)
文摘Vanadium pentoxide, borax, boron carbide and sodium fluoride were used to grow vanadium carbide coating on surface of Crl2 steel at 950℃ by TD process. The coating of vanadium carbide （VC） extended the serve-life period of Crl2 steel as punching die. Kinetics of vanadium carbide coating growth was brought forward and verified by comparison of the mathematical model with the experimental results. The thickness of coating was illustrated by SEM. The chemical constituent of coating and remnants were tested by X-ray diffraction （XRD） and X-ray energy dispersive spectroscopy （EDS）. To increase the thickness, rare earth silicon powder （FeSiRe23） was added to the borax salt bath. The analysis of XRD revealed that FeSiRe23 increased the depth of vanadium car-bide coating as reducing agent and catalysis.
