CN102950273B - Method for manufacturing monotectic alloy compound wire with dispersion surface layer - Google Patents

Abstract

The invention belongs to a technology for manufacturing alloy wires, and particularly discloses a method for manufacturing a monotectic alloy compound wire with a dispersion surface layer. A continuous solidification technology under the action of a direct-current electric field is adopted, the solidification speed ranges from 5mm/s to 50mm/s, monotectic alloy and insulating materials (such as metal-oxide ceramics and boron nitride) are selected to be used as materials of a crucible (or coatings of the inner wall of the crucible and the inner wall of a crystallizer), and the monotectic alloy compound wire with the dispersion surface layer is manufactured by the continuous solidification technology under the action of the direct-current electric field. The proper monotectic alloy (such as Al-Pb, Al-Bi and Cu-Co alloy) and the proper insulating materials (such as the metal-oxide ceramics and the boron nitride) are selected to be used as the materials of the crucible (or the coatings of the inner wall of the crucible and the inner wall of the crystallizer), and continuous solidification is carried out under the action of the direct-current electric field, so that dispersion liquid drops migrate to the surface of a test sample and form the dispersion layer in a liquid-liquid phase change process of the monotectic alloy, the monotectic alloy compound wire with the dispersion surface layer is manufactured, and industrial requirements are met.

Description

A kind of preparation method of the monotectic alloy composite wire with disperse phase superficial layer

Technical field

The invention belongs to alloy wire technology of preparing, specifically continuous solidification preparation method under a kind of DC electric field effect of the monotectic alloy composite wire with disperse phase superficial layer.

Background technology

Metal (alloy) composite wire, as copper covered steel, copper cover aluminum, tin copper-clad, copper cover aluminum-magnesium alloy bar/wire rod etc., has good comprehensive physical, mechanics, the performance such as anti-corrosion, has broad application prospects in the industry such as electric power, traffic.Exploitation specialty metal (alloy) composite wire and technology of preparing thereof are one of mains direction of studying of material science in recent years, in widespread attention, now develop the technology of preparing of various metals composite wire, as biobelt roll compacting method, hydrostatic extrusion method, galvanoplastic, hot dip coating method, cladding welding, tiretube process etc.

Summary of the invention

The object of the present invention is to provide a kind of preparation method of the monotectic alloy composite wire with disperse phase superficial layer, propose by suitably choosing alloy system, alloying component and crucible (or continuous cast mold coating) material, by carry out continuous solidification under DC electric field effect, disperse phase drop in Duringliquid-liquid Phase Transformation is moved to specimen surface, obtain the monotectic alloy composite wire with disperse phase superficial layer.

Technical scheme of the present invention is:

A kind of preparation method of the monotectic alloy composite wire with disperse phase superficial layer, adopt the continuous solidification technology under DC electric field effect, setting rate is 5-50mm/s (being preferably 5-20mm/s), choose monotectic alloy, adopting insulating materials (as metal oxide ceramic, boron nitride etc.) be crucible (or insulating coating of crucible, crystallizer inwall) material, prepares the monotectic alloy composite wire with disperse phase superficial layer.

Described alloy is selected the monotectic type alloy that disperse phase Conductivity Ratio matrix phase electrical conductivity is low, as: aluminium base Al-Pb, Al-Bi, Al-In are associated gold, and copper base Cu-Co is associated gold etc.

Described Al-Pb monotectic alloy is Al-(5-15) wt%Pb.

Described monotectic alloy recombination line diameter is 1-20mm.

Principle of the present invention is as follows:

Monotectic alloy (seeing Fig. 1) coagulates in process continuously, and disperse phase drop can radially move to crucible (crystallizer) central shaft under the effect of thermograde in melt, i.e. Ma rangoni migration.Disperse phase drop is along sample Marangoni migration velocity radially

for:

$V_M^r=-\frac{{2\mathrm{\λ}}_{m}R}{({2\mathrm{\λ}}_m+{\mathrm{\λ}}_D)({2\mathrm{\η}}_m+{3\mathrm{\η}}_D)}\frac{\mathrm{d\γ}}{\mathrm{dT}}\frac{\∂T}{\∂r}---\left(1\right)$

In formula, γ is the interfacial tension between disperse phase drop and matrix melt, and T is temperature, λ _d, λ _mfor the thermal conductivity of disperse phase drop and matrix melt, η _dand η _mfor the dynamic viscosity (under matrix melt temperature conditions of living in) of disperse phase drop and matrix melt, r is along sample coordinate length (initial point that sample axis is radial coordinate) radially,

for the temperature coefficient of interfacial tension between disperse phase drop and matrix melt,

for along sample thermograde radially, R is disperse phase droplet radius.

Therefore,, under common continuous solidification condition, after Solidified Monotectic Alloy, wire surface presents the barren layer of a disperse phase, sees Fig. 2.

The present invention is by choosing the monotectic type alloy that disperse phase Conductivity Ratio matrix phase electrical conductivity is low (being associated gold etc. as Al base Al-Pb, Al-Bi), using insulating materials (as metal oxide ceramic, boron nitride etc.) as crucible (or coating of crucible, crystallizer inwall) material, makes melt along solidifying under crucible (crystallizer) axial DC electric field action.Between DC current and the magnetic field of its generation, interact, in melt, produce electromagnetic force field radially.Because the electrical conductivity of matrix melt is higher than the electrical conductivity of disperse phase drop, under given DC electric field effect, the current density of passing through in matrix melt and suffered electromagnetic force density are also higher, thereby, disperse phase drop is subject to an effect of making a concerted effort along sample electromagnetism radially and tends to sample outer surface migration, disperse phase drop suffered along the sample electromagnetism radially migration velocity (V that (F) and this electromagnetic force cause that makes a concerted effort _e) be:

$F=\frac{4}{3}\frac{{\mathrm{\σ}}_D-{\mathrm{\σ}}_m}{{\mathrm{\σ}}_D+{2\mathrm{\σ}}_m}{\mathrm{\π\μrj}}^2{R}^3---\left(2\right)$

$V_E=\frac{2}{3}\frac{{\mathrm{\σ}}_D-{\mathrm{\σ}}_m}{{\mathrm{\σ}}_D+{2\mathrm{\σ}}_m}{\mathrm{\μrj}}^2{R}^2\frac{{\mathrm{\η}}_m+{\mathrm{\η}}_D}{{\mathrm{\η}}_m({3\mathrm{\η}}_D+{2\mathrm{\η}}_m)}---\left(3\right)$

In formula, j is the current density by melt, σ _d, σ _mfor the electrical conductivity of disperse phase drop and matrix melt, μ is the magnetic conductivity of matrix melt, and π=3.14 are constant.

From formula (1) and (3), the disperse phase drop that is R for radius, in the time meeting formula (4) by the current density of melt, the migration velocity of the disperse phase drop that electric field causes is greater than the Marangoni migration velocity of the disperse phase drop being caused by melt radial symmetry gradient,, disperse phase drop moves to crucible (crystallizer) inner surface direction.

$j>\sqrt{3\frac{{\mathrm{\λ}}_m}{({2\mathrm{\λ}}_m+{\mathrm{\λ}}_D)}\frac{{\mathrm{\σ}}_D+{2\mathrm{\σ}}_m}{{\mathrm{\σ}}_D-{\mathrm{\σ}}_m}\frac{{\mathrm{\η}}_m}{{\mathrm{\η}}_m+{\mathrm{\η}}_D}\frac{1}{\mathrm{\μ}}\frac{\mathrm{d\γ}}{\mathrm{dT}}\frac{\∂T}{\∂r}\frac{1}{R}\frac{1}{r}}---\left(4\right)$

In the time that the current density by melt can make most disperse phase drops in melt all meet formula (4), disperse phase drop can cause solidifying rear wire surface to the migration of crucible (crystallizer) inner surface direction and present a disperse phase layer.

In real process, can according to wire rod tissue need to suitably choose applied current density, if that is: wish the thinner thickness of wire surface disperse phase layer, can apply a current density being provided by formula (5); If wish that the thickness of surface dispersion phase layer is thicker, will apply a current density being provided by formula (6).

$\sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.5R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.5R_S)}\frac{1}{{<R>}_P}\frac{1}{0.5R_S}}\&GreaterEqual;j\&GreaterEqual;---\left(5\right)$

$\sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.8R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.8R_S)}\frac{1}{{<R>}_P}\frac{1}{0.8R_S}}$

$j>\sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.5R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.5R_S)}\frac{1}{{<R>}_P}\frac{1}{0.5R_S}}---\left(6\right)$

<R> in formula _pfor solidifying disperse phase particle mean radius in sample, R _sfor radius of specimen, T ₀for the monotectic point temperature of alloy, λ _d0, λ _m0for the thermal conductivity of disperse phase drop at monotectic point temperature and matrix melt, η _d0and η _m0for the dynamic viscosity of disperse phase drop at monotectic point temperature and matrix melt, σ _d0, σ _m0for the electrical conductivity of disperse phase drop at monotectic point temperature and matrix melt, μ ₀for the magnetic conductivity of monotectic point temperature lower substrate melt,

for r=0.5R at monotectic point temperature _sthe temperature coefficient of interfacial tension between place's disperse phase drop and matrix melt,

for r=0.5R at monotectic point temperature _slocate along sample thermograde radially,

for r=0.8R at monotectic point temperature _sthe temperature coefficient of interfacial tension between place's disperse phase drop and matrix melt,

for r=0.8R at monotectic point temperature _splace is along sample thermograde radially.

The invention has the beneficial effects as follows:

The present invention chooses suitable monotectic type alloy system and alloying component (as aluminium base Al-Pb, Al-Bi, Al-In are associated gold, copper base Cu-Co is associated gold etc.), use insulating materials (as metal oxide ceramic, boron nitride etc.) as crucible (or coating of crucible, crystallizer inwall) material, utilize the continuous solidification technology under DC electric field effect, make to move to specimen surface under the effect in electromagnetic force of disperse phase drop that monotectic type alloy forms in liquid-liquid phase change process, acquisition has the monotectic alloy composite wire of disperse phase superficial layer, meets industrial requirement.

Accompanying drawing explanation

Fig. 1 is the signal phasor of monotectic type alloy.

Fig. 2 is the tissue that while not applying electric field, Al-7wt%Pb alloy is thought sample after 8mm/s speed continuous solidification.In figure, black is Al matrix mutually, and white is rich Pb phase mutually.In process of setting, along sample thermograde radially, rich Pb phase drop is moved to specimen surface, cause forming a poor Pb layer at specimen surface.

In order to apply electric field, (current density is 438A/cm to Fig. 3 ²) time Al-7wt%Pb alloy think the tissue of sample after 8mm/s speed continuous solidification.In figure, black is Al matrix mutually, and white is rich Pb phase mutually.The disperse phase drop that in process of setting, electric field causes is greater than the disperse phase drop that caused by the melt radial symmetry gradient migration velocity to sample central shaft to the migration velocity of specimen surface,, disperse phase drop moves to specimen surface, cause forming Pb layer mutually at specimen surface, obtained the monotectic alloy composite wire with disperse phase superficial layer.

In order to apply electric field, (current density is 195A/cm to Fig. 4 ²) time Al-7wt%Pb alloy think the tissue of sample after 8mm/s speed continuous solidification.In figure, black is Al matrix mutually, and white is rich Pb phase mutually.The disperse phase drop that in process of setting, electric field causes is slightly larger than the disperse phase drop that caused by the melt radial symmetry gradient migration velocity to sample central shaft to the migration velocity of specimen surface,, disperse phase drop moves to specimen surface, cause forming a very thin Pb layer mutually at specimen surface, obtained the monotectic alloy composite wire with disperse phase superficial layer.

The specific embodiment

Research shows, conventionally, under continuous solidification condition, the temperature of specimen surface is lower, heart portion temperature is higher, monotectic type alloy is in liquid-liquid phase change process, disperse phase drop does Marangoni migration under the effect of thermograde to sample center, finally cause forming a poor Pb layer at specimen surface, as shown in Figure 2.When melt is passed to along crucible axis to DC current time, between electric current and the induced field of its generation, interact, in melt, form electromagnetic force field radially.When matrix melt electrical conductivity is during higher than the electrical conductivity of disperse phase drop, under given DC electric field effect, the current density of passing through in matrix melt and suffered electromagnetic force density are higher, and disperse phase drop is subject to the effect that the electromagnetism of a sensing specimen surface makes a concerted effort and tends to move to specimen surface.This movement velocity direction is contrary with the Ma rangoni migratory direction of the disperse phase drop being caused by thermograde in melt, therefore, in the time that the current density of passing through is enough large, the disperse phase drop migration velocity that electromagnetic force causes plays a leading role, in process of setting, disperse phase drop moves to specimen surface, forms the monotectic alloy composite wire with disperse phase superficial layer.

Accordingly, we utilize the continuous solidification technology under electric field action by selecting suitable monotectic alloy and crucible material, have prepared the monotectic alloy composite wire with disperse phase superficial layer, as shown in Figure 3.

Embodiment 1

As shown in Figure 3, use the continuous solidification device under electric field action, select Al-7wt%Pb alloy, with boron nitride be crucible material, setting rate is 8mm/s, is 438A/cm by the current density of melt ², prepare the Al-Pb alloy composite wire with Pb phase surface layer, its diameter is 4mm.

Its preparation process is as follows:

With resistance furnace melting monotectic alloy melt, by obtaining homogeneous melt in 1223K insulation, stirring after 20 minutes; To the logical direct current of melt, current density is 438A/cm ², start, to the middle pull sample of cooling medium (liquid gallium indium stannum alloy), to carry out continuous solidification.

Experiment shows, the mean radius of solidifying plumbous phase particle in sample is about <R> _p=2um, can be calculated and be greater than 294A/cm when current density by formula (6) ²time can obtain thicker disperse phase layer at specimen surface.The current density of this experiment is 438A/cm ², meet formula (6), so alloy has formed Pb phase surface layer at specimen surface in process of setting.

Embodiment 2

As shown in Figure 4, use the continuous solidification device under electric field action, select Al-7wt%Pb alloy, with boron nitride be crucible material, setting rate is 8mm/s, is 195A/cm by the current density of melt ², prepare the Al-Pb alloy composite wire with very thin Pb phase surface layer, its diameter is 6mm.

Its preparation process is as follows:

With resistance furnace melting monotectic alloy melt, by obtaining homogeneous melt in 1223K insulation, stirring after 20 minutes; To the logical direct current of melt, current density is 195A/cm ², start, to the middle pull sample of cooling medium (liquid gallium indium stannum alloy), to carry out continuous solidification.

Experiment shows, the mean radius of solidifying plumbous phase particle in sample is about <R> _p=2um, can be calculated in the time that current density is between 190-294 by formula (5), can obtain thinner disperse phase layer at specimen surface.The current density of this experiment is 195A/cm ², within the scope of formula (5) prediction, so alloy has formed thinner Pb phase surface layer at specimen surface in process of setting.

Claims (5)

1. a preparation method with the alloy composite wire of disperse phase superficial layer, is characterized in that:

Adopt the continuous solidification technology under DC electric field effect, choosing monotectic alloy is raw material, for continuous solidification or continuous directional solidification device, setting rate is at 5-50mm/s, adopting insulating materials is the coating material of crucible or crystallizer material or crucible or crystallizer inwall, axially pass into DC current to monotectic alloy melt along crucible or crystallizer, preparation has the monotectic alloy composite wire of disperse phase superficial layer;

When the current density of the described DC current by melt meets formula (5), the thinner thickness of wire surface disperse phase layer;

$\begin{array}{c}\sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.5R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.5R_S)}\frac{1}{<{R>}_P}\frac{1}{0.5R_S}}\&GreaterEqual;j\&GreaterEqual;\\ \sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.8R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.8R_S)}\frac{1}{<{R>}_P}\frac{1}{0.8R_S}}\end{array}---\left(5\right);$

When the current density of the described DC current by melt meets formula (6), the thickness of wire surface disperse phase layer is thicker;

$j>\sqrt{3\frac{{\mathrm{\&lambda;}}_{m0}}{(2{\mathrm{\&lambda;}}_{m0}+{\mathrm{\&lambda;}}_{D0})}\frac{{\mathrm{\&sigma;}}_{D0}+2{\mathrm{\&sigma;}}_{m0}}{{\mathrm{\&sigma;}}_{D0}-{\mathrm{\&sigma;}}_{m0}}\frac{{\mathrm{\&eta;}}_{m0}}{{\mathrm{\&eta;}}_{m0}+{\mathrm{\&eta;}}_{D0}}\frac{1}{{\mathrm{\&mu;}}_0}\frac{\mathrm{d\&gamma;}}{\mathrm{dT}}{|}_{(T=T_0,r=0.5R_S)}\frac{\&PartialD;T}{\&PartialD;r}{|}_{(T=T_0,r=0.5R_S)}\frac{1}{<{R>}_P}\frac{1}{0.5R_S}}---\left(6\right);$

<R> in formula _pfor solidifying disperse phase particle mean radius in sample, R _sfor radius of specimen, T ₀for the monotectic point temperature of alloy, λ _d0, λ _m0for the thermal conductivity of disperse phase drop at monotectic point temperature and matrix melt, η _d0and η _m0for the dynamic viscosity of disperse phase drop at monotectic point temperature and matrix melt, σ _d0, σ _m0for the electrical conductivity of disperse phase drop at monotectic point temperature and matrix melt, μ ₀for the magnetic conductivity of monotectic point temperature lower substrate melt,

for r=0.5R at monotectic point temperature _sthe temperature coefficient of interfacial tension between place's disperse phase drop and matrix melt,

for r=0.5R at monotectic point temperature _slocate along sample thermograde radially,

for r=0.8R at monotectic point temperature _sthe temperature coefficient of interfacial tension between place's disperse phase drop and matrix melt,

for r=0.8R at monotectic point temperature _splace is along sample thermograde radially.

2. according to preparation method claimed in claim 1, it is characterized in that: described insulating materials is metal oxide ceramic, nitride ceramics, carbide ceramics, boride ceramics or silicide ceramics.

3. according to preparation method claimed in claim 1, it is characterized in that: described monotectic alloy is the monotectic type alloy that disperse phase Conductivity Ratio matrix phase electrical conductivity is low.

4. according to preparation method claimed in claim 1, it is characterized in that: described monotectic alloy is that aluminium base Al-Pb is associated that gold, Al-Bi are associated gold, Al-In is associated gold or copper base Cu-Co is associated gold.

5. according to preparation method claimed in claim 1, it is characterized in that: the diameter of the monotectic alloy wire rod of described preparation is 1-20mm.

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