CN100431744C - Preparation method of Mo-Cu composite powder - Google Patents

Abstract

A Mo-Cu composite powder is provided which is comprised of individual finite particles each having a copper phase and a molybdenum phase wherein the molybdenum phase substantially encapsulates the copper phase. The composite powder may be consolidated by conventional P/M techniques and sintered without copper bleedout according to the method described herein to produce Mo-Cu pseudoalloy articles having very good shape retention, a high sintered density, and a fine microstructure.

Description

The preparation method of Mo-Cu composite powder

The application is that application number is 01117875.2, the applying date is March 29 calendar year 2001, denomination of invention is divided an application for the application for a patent for invention of " Mo-Cu composite powder ".

Technical field

The present invention relates to molybdenum copper (Mo-Cu) composite powder, relate in particular to the Mo-Cu composite powder that is used for making the element that is used for electronics, electronic packaging and electro-engineering purposes, and the preparation method of described composite powder.The example of these purposes comprises fin, radiator, electric contact piece and welding electrode.

Background technology

The property class of Mo-Cu pseudo-alloy is similar to the W-Cu pseudo-alloy.Yet they have the lighter and higher additional advantage of machinability of weight, and this makes them more be applicable to miniature electronic industry.

One of common methods of the workpiece that making is made of the Mo-Cu pseudo-alloy comprises with liquid copper penetration advancing in the porous molybdenum blank of independent sintering.The workpiece that is permeated has the solid-state molybdenum framework as the backbone of pseudo-alloy.This member keeps liquid copper by capillary force during infiltration (and high-temperature operation).A shortcoming of this permeating method is that it does not allow to be similar to the manufacturing of netted or mesh members.Therefore, just need many machine operations to obtain permeating the net shape of workpiece.

Other method that forms the Mo-Cu workpiece comprises employing powder metallurgy (P/M) technology, and for example pressure sintering, blast pressing, injection moulding, belt shaping and the rolling mixture of molybdenum and copper powders may that makes are fixed.Different with permeating method, these methods are not used in the independent step of sintering molybdenum framework.Therefore, the workpiece of making by the P/M method is not that to lack the molybdenum framework fully be exactly that its framed intensity reduces.Suggestion with high thrust, again suppress again sintering and under pressure sintering (hot pressing) improve that Mo-Mo contacts and the intensity of molybdenum framework.Though the P/M technology allows to be similar to the manufacturing of netted or mesh members, to fully fine and close, it is complicated lacking under the situation that solubility, molybdenum can ooze out from component during sintering for the wetability difference and the copper of copper in the Mo-Cu system with workpiece sintering.In addition, add sintering activator for example nickel and cobalt improve packing the thermal conductivity of Mo-Cu pseudo-alloy be harmful to, and thermal conductivity is vital for many electronics industry purposes.

In order to improve the uniformity and the density of the Mo-Cu pseudo-alloy of making by the P/M method, once adopted the Mo-Cu composite powder, wherein molybdenum particles is coated on copper by chemical deposition or electro-plating method.Yet this copper coating has reduced the contact area between the molybdenum particles and has reduced the intensity of molybdenum framework.And these powder do not prevent that copper oozes out during sintering from component, and still need hot pressing to improve the sintered density of workpiece.Therefore, a kind of like this Mo-Cu composite powder can be arranged preferably, this powder can be applied in the P/M method to have the netted of firm sintering molybdenum framework or is similar to netted Mo-Cu workpiece to form under the situation that does not have copper to ooze out.

Summary of the invention

The objective of the invention is to eliminate those shortcomings of prior art.

Another object of the present invention is to provide has a kind of Mo-Cu composite powder that distributes mutually, and this is distributed with mutually to be beneficial to and forms firm molybdenum framework and help during sintering copper in the infiltration of framework inside.

A further object of the invention is to provide a kind of a kind of molybdenum-copper composite oxide power with molybdenum-copper combined oxidation powder of height hybrid metal phase that is used to produce.

A further object of the invention is to provide a kind of making to have firm molybdenum member and high sintered density and does not have the P/M method of molybdenum-copper pseudo-alloy workpiece that copper oozes out.

According to one object of the present invention, a kind of molybdenum-copper composite powder is provided, it comprises separately limited particulate, each particulate have copper mutually and molybdenum mutually, wherein the molybdenum phase is being wrapped the copper phase basically.

According to another object of the present invention, provide a kind of making CuMoO ₄The method of base combined oxidation powder, this method comprises:

(a) form the mixture of molybdenum oxide and cupric oxide, molybdenum oxide conduct oneself with dignity ammonium molybdate, metamolybdic acid ammonium or molybdenum dioxide; And

(b) under a certain temperature, fire this mixture time enough, to form CuMoO ₄Base composite oxidate.

According to another object of the present invention, molybdenum-copper composite powder of the present invention is made by the following method:

(a) first step is earlier CuMoO ₄Base combined oxidation powder reduction with the original mixture of the oxide that forms a kind of metallic copper and molybdenum, and can not form the cuprous phase of low-melting molybdic acid; And

(b) second step was this original mixture reduction time enough under a temperature, so that molybdenum oxide is reduced into metal molybdenum.

In the present invention is aspect another, a kind of method that is used to make molybdenum-copper pseudo-alloy also is provided, this method comprises:

(a) make molybdenum-copper composite powder fixed forming a kind of briquetting, the copper content of this molybdenum-copper composite powder is approximately 2wt.% to 40wt.% and comprise independent limited particulate, each particulate have copper mutually and molybdenum mutually, wherein the molybdenum phase is being wrapped the copper phase basically;

(b) in first sintering step this briquetting of sintering temperature between about 1030 ℃ to 1050 ℃ to form the molybdenum framework;

(c) in second sintering step, under the temperature between about 1050 ℃ to 1080 ℃, carry out sintering to be about the briquetting that 26wt.% makes to the composite powder of 40wt.% by copper content, and under the temperature between about 1085 ℃ to 1400 ℃, carry out sintering be about the briquetting that 2wt.% makes to the composite powder of 25wt.% by copper content.

Description of drawings

Fig. 1 for by relative copper content be 15wt.% based on CuMoO ₄The combined oxidation powder under 300 ℃ hydrogen reduction and the X-ray diffraction pattern of the first stage of reduction product that forms.

Fig. 2 is the SEM microphoto of the section of the agglomerate of molybdenum-copper composite powder of adopting the back scattered electron formation method and obtaining.

Fig. 3 is the enlarged drawing of the limited particulate that demonstrates in photo shown in Figure 2.

Fig. 4 is the SEM microphoto of the end face of Mo-15Cu pseudo-alloy.

Fig. 5 is the SEM microphoto of the end face of Mo-40Cu pseudo-alloy.

The specific embodiment

In order better to understand the present invention and other and further purpose, advantage and its performance, then will be in conjunction with above-mentioned accompanying drawing with reference to following specification and the appended claims.

We invent out a kind of molybdenum-copper (Mo-Cu) composite powder, and this powder contains limited two-phase particulate, each particulate have copper mutually and molybdenum mutually, wherein the copper phase is being wrapped mutually by molybdenum basically.The color of a Mo-Cu composite powder that becomes granule of the present invention is the grey of pure molybdenum powder, and this color is with to wrap copper molybdenum mutually basically consistent.Preferably, this Mo-Cu composite powder contains the Cu of about 2wt.% to 40wt.%.

Usually, as-reduced Mo-Cu composite powder constitutes (being approximately the order of magnitude of 15 μ m to 25 μ m) by limited two-phase particulate than buckshot aggregate.Under SEM observes, the limited particulate in this demonstrate into irregularly shaped and size at about 0.5 μ m in the scope of 1.5 μ m.Each limited particulate has the molybdenum network of sintering, and space wherein is filled with copper.The unique distribution of this unique Mo and Cu phase provides substantially by the sealing of the relative Cu phase of Mo, and causes the highest degree of mixing in bigger granule.

Because copper is being wrapped mutually by molybdenum, so just can realize having the intensified-sintered process of several desired characteristics.These features comprise: (1) forms the contact of Mo-Mo particulate after compacted powder; (2) the closely knit basically Mo framework of sintering before molten copper; (3) internal penetration of liquid copper in this framework, and remain on this framework inside by capillary force; (4) under the situation that has liquid copper to exist and do not have liquid copper from this densification thing, to ooze out, carry out sintering.

This Mo-Cu composite powder is by having the molybdenum trioxide (MoO of controlled quentity controlled variable ₃) produce based on the chemical synthesis of the composite oxides system of molybdic acid copper and hydrogen reduction.Usually, molybdic acid copper (CuMoO ₄) be to pass through MoO ₃With CuO or Cu ₂In 600 ℃ air, make between the O through 40 hours solid phase reaction.Yet, as the percentage of whole tenor (Cu+Mo), CuMoO ₄The content of middle metallic copper is quite high, is approximately 40 percentage by weights (wt.%).This is more much higher than the copper content in the Mo-Cu pseudo-alloy used in some industrial uses.For example, the copper content of requirement in the Mo-Cu material is 15-25wt.% for electronic packaging.This problem is by in a wide region, by MoO ₃Second phase synthesizing jointly of variable quantity transform CuMoO ₄The copper content of base composite oxidate solves.CuMoO ₄And MoO ₃The combination of phase is reduced in the desired scope of electronic application the copper content of these composite oxides.Preferably in the percentage of whole tenor, this CuMoO ₄The copper content of base composite oxidate can change between the 40wt.% at about 2wt.%.Unless otherwise noted, here recently represent for the relative copper content of composite oxides with the percentage of oxide total metal contents in soil.

CuMoO ₄ Synthesizing of base composite oxidate

Synthesize by solid phase and to prepare this composite oxides.The ratio of solid reactant (oxide of copper and molybdenum) will be enough to the synthetic CuMoO that contains ₄The MoO of phase and institute's controlled quentity controlled variable ₃The final products of phase.The ratio of synthetic phase (MoO especially ₃Amount) controlled CuMoO ₄Copper content in the base composite oxidate.Preferred CuMoO ₄The general formula of base composite oxidate based on mole, is represented as CuMoO ₄+ xMoO ₃, wherein x is approximately 29 to 0.Should common synthetic CuMoO ₄And MoO ₃Be present in mutually in each composite oxide particle, this just forms the copper and the molybdenum of very high degree of mixing.

In preferred synthetic method, adopt the combination of two kinds of reactants: (i) molybdenum oxide and the cupric oxide of complexing, especially heavy ammonium molybdate (ADM, (NH ₄) ₂Mo ₂O ₇) or molybdic acid six ammoniums (APM, (NH ₄) ₆Mo ₇O ₂₄4H ₂O) and cuprous oxide (Cu ₂O) or cupric oxide (CuO), and (ii) molybdenum dioxide (MoO ₂) and cuprous oxide or cupric oxide.In the air of temperature more than 250 ℃, the complexing molybdenum oxide is subjected to thermal decomposition (as, (NH ₄) ₂Mo ₂O ₇→ 2MoO ₃+ 2NH ₃+ H ₂And Cu O), ₂O and MoO ₂Be oxidized to CuO and MoO ₃These change surface area and the surface energy that has increased reactant significantly mutually, thereby have accelerated the inter-diffusion reaction and the CuMoO of they solid phases ₄The formation of base composite oxidate.Therefore, CuMoO ₄Base composite oxidate can form by these hopcalites are only fired under about 650 ℃ to 750 ℃ temperature in about 5 hours.

Silicon is selected as and is used for holding the synthetic CuMoO of solid phase ₄The material of base composite oxidate, because molybdenum trioxide reacts with most other metals easily and forms molybdate, and metal oxide is used to make boat and the dish that is used for the solid phase building-up process traditionally.Compare with the bulk silicon content in the reactant, use the silicon boat can increase the silicone content of composite oxides a little.Yet it is lower that the content of bulk silicon keeps, and be considered to can not to influence basically the electric conductivity/thermal conductivity of the caking power or the Mo-Cu pseudo-alloy of final Mo-Cu composite powder.

The first preferred synthetic method can be passed through relevant ADM and Cu ₂The reaction of O illustrates.The composition of ADM can be used NH ₄) ₂O2MoO ₃Represent, and this synthetic reaction is:

0.5Cu ₂O+n[(NH ₄) ₂O·2MoO ₃]+0.25O ₂→CuMoO ₄+(2n-1)MoO ₃+2nNH ₃+nH ₂O

By in about scope of 15.0 to 0.5, changing parameter n, can be with the CuMoO that synthesizes by above-mentioned reaction ₄Relative copper content in the base composite oxidate is controlled at about 2wt.% in the scope of 40wt.%.

Embodiment 1

At CuMoO ₄In base composite oxidate synthetic, adopting median particle is that the AMD of 198.8 μ m and cuprous oxide that median particle is 14.5 μ m are as solid reactant.(employing Microtrac MT unless otherwise, the determined granularity of X-100 Particle Size Analyzer.) in these trials the gross weight of solid reactant 0.5 in the scope of 1.0kg.Grind in the spherical mill of corundum, the weight ratio of corundum and reactant changes in the 1.5-1 scope in the grinding.The time of grinding is individual 1 hour.The filbert of the oxide mixture that is ground is to have mixed ADM (white) and Cu ₂The result of O (brown).It is preferred that these reactants are adopted grinding, because the median particle of ADM and APM powder is greater than the median particle of cupric oxide usually, this makes and is difficult to obtain uniform mixture by mechanical mixture separately.

In trial furnace, in air, carry out synthetic reaction with an alumina tube.The silicon boat is used as reaction vessel.The oxide that is ground that 150g is heavy forms about 0.5 inch bed in boat dark.The speed that furnace temperature increases is 2 ℃/min.Synthetic temperature is 750 ℃, and is incubated 5 hours under this temperature.Carry out five tests, wherein the relative copper content of the composite oxides that synthesized changes in 8 to 40wt.% scope.

All synthetic composite oxides form agglomerate, and these agglomerates need pulverize in the alms bowl body.Caking ascribes the high diffusion activity of high reaction temperature and the solid reactant that is ground to, makes MoO especially at the scene ₃The time.Milling material is filtered into-100mesh.Synthetic powder has CuMoO ₄The yellow green feature of base composite oxidate.Element and X-ray diffraction (XRD) facies analysis is used as powder characteristics and identifies.With MoO ₃(3.26

) and CuMoO ₄(3.73

) relevant main XRD peak is used for calculating the strength ratio at XRD peak.Table 1 is according to the quantity of reactant, and the calculated value that is used for composite oxides and the measured value of synthesizing composite oxide are compared.

Table 1

The measured value of described relative copper content and the correlation between the calculated value, along with the copper content growth of synthetic powder, and in 95.0% to 99.75% scope.Between the trend of the predetermined ratio of product phase and actual specific and copper content, also observe good correlation.

In second kind and preferred synthetic method, frangible CuMoO ₄Base composite oxidate is to be made by the dewatered solid reactant of not milling, and wherein at least a reactant is subjected to phase transformation between synthesis phase, for example Xian Chang MoO ₂Be oxidized to MoO ₃And Cu ₂O is oxidized to CuO.When in first method, the copper content of synthesizing composite oxide is controlled by changing the reactive chemistry equivalent.Synthetic reaction adopts one mole of CuO or half mole of Cu ₂O.For using Cu ₂O, its reaction can be represented as:

0.5Cu ₂O+nMnO ₂+(0.5n+0.25)O ₂→CuMoO ₄+(n-1)MoO ₃

By in about scope of 30.0 to 1.0, changing parameter n, can be with CuMoO ₄Relative copper content in the base composite oxidate is controlled at about 2wt.% in the scope of 40wt.%.And, because the median particle of molybdenum dioxide and cupric oxide under the situation of not grinding, by mechanical mixture, can obtain the mixture of uniform initial solid reactant in identical magnitude.

Embodiment 2

In this embodiment, use MoO ₂(D ₅₀=5.3 μ m), Cu ₂O (D ₅₀=14.5 μ m) and CuO (D ₅₀=13.3 μ m) prepare this composite oxides.By at breadboard V-blender these oxides being mixed 30 minutes, preparing gross weight is 0.5 to 1.0kg starting mixt.The color of this starting mixt is from brown (MoO ₂+ Cu ₂O) to pitchy (MoO ₂+ CuO).

In air, adopt with embodiment 1 in the same equipment synthesize.The oxide that is mixed that 100g is heavy forms about 0.5 inch bed in boat dark.The speed that furnace temperature rises is 2 ℃/minute.Synthesis temperature is 650 ℃, and is incubated 5 hours under this temperature.Relative copper content in this synthesizing composite oxide changes in 5 to 40wt.% scope.

In each case, form evenly loose agglomerate.This material is very frangible, and can be fragmented into powder by rubbing between finger.Should have CuMoO by synthetic powder ₄The yellow green feature of base synthesis oxide.Powder is screened to be-100 orders and through in the same analysis described in the embodiment 1.Data description in table 2 by MoO ₂And Cu ₂O (row A) and MoO ₂And the characteristic of the synthetic composite oxide power of CuO (row B).

Table 2

The measured value and the correlation between the calculated value of described relative copper content increase along with copper content, and in 93.4% to 99.0% scope.Between the tendency of the relative copper content of predetermined ratio of product phase, also observe good correlation with actual specific.

Embodiment 3

Carry out additional testing, to prove at CuMoO ₄Copper content in the base composite oxidate can be adjusted to the amount of appointment by the amount that is controlled at the cupric oxide of participating in synthetic.Adopted and by the reaction the desired quantity of stoichiometry compare the Cu of 4wt.% ₂O's is excessive.Just the same among experiment condition and the embodiment 2.Table 3 compares the actual copper content of synthetic composite oxides with by the specified copper content of stoichiometry.The correlation of the numerical value of actual copper content and appointment is calculated as the actual value of copper content and the ratio between the designated value.

Table 3

The copper wt.% of appointment	Actual value (no Cu 2O is excessive)	Correlation	Actual value (the Cu that 4wt.% is arranged 2O is excessive)	Correlation
					5	4.68	0.936	5.08	1.016
10	9.64	0.964	10.39	1.039
					15	14.45	0.963	15.39	1.026
20	19.30	0.965	19.63	0.981
					25	24.39	0.975	24.97	0.998
30	29.52	0.984	29.75	0.991
					35	34.53	0.986	35.76	1.022
40	39.40	0.985	40.53	1.013

These results prove, add than the cupric oxide reactant by the desired excessive 4wt.% of stoichiometry, can be used for the relative copper content in resulting composite oxides is adjusted to more amount near appointment.

Embodiment 4

In the large belt stove, the CuMoO that to synthesize its relative copper content be 15wt.% ₄Base composite oxidate.Solid reactant is MoO ₂And Cu ₂O.In large-scale V blender, prepare its Cu of 300kg ₂The mixture of the reactant of the excessive 4wt.% of O content.1.5kg starting mixt to form about 0.5 inch bed in silicone disc dark.In mean temperature is 675 ℃ air, synthesize, and its mean residence time is approximately 4 hours.The productivity ratio of this stove is approximately per hour 6kg composite oxides.Want the final products of Synthetic 2 68kg altogether.This material is discharged into from silicone disc on the screen cloth of vibration, and is cracked and be filtered into-60 orders and be collected in the funnel.In the V blender, mix this product and analyze its size distribution and copper content.The sample of final products milled and screen be to carry out XRD analysis then by-100 orders.Thereby obtain following product feature:

Size distribution: D ₉₀=18.5 μ m

D ₅₀＝5.5μm

D ₁₀＝2.1μm

Relative copper content: 15.36wt.%

MoO ₃/ CuMoO ₄XRD peak intensity ratio: 1.8

In producing stove the phase composition of synthetic composite oxide power and copper content and in the laboratory respective performances of synthetic powder closely similar.

CuMoO ₄ The reduction of base composite oxidate

One of key issue of the oxide powder mixture that relates to mechanical mixture that exists in conventional method comes from significant difference between the reduction temperature of oxide of molybdenum and copper.This difference causes that too early appearance is by coalescent and produce copper and its segregation.This causes Mo and Cu uneven distribution mutually in the Mo-Cu composite powder of reduction again.On the contrary, by synthetic CuMoO ₄The Mo-Cu composite powder that hydrogen reduction generated of base composite oxidate has extraordinary uniformity.At synthetic CuMoO ₄In the base composite oxidate, atomic energy level that contacts between copper and the molybdenum and the difference aspect reduction temperature, can be used for the order that fine low control metal occurs mutually, thereby cause a kind of uniform Mo-Cu composite metal powder that is made of independent diphase particles, wherein Mo is wrapping the copper phase mutually basically.

In a preferred embodiment, CuMoO ₄The hydrogen reduction of base composite oxidate was carried out in two stages.First stage of reduction carries out under about 400 ℃ temperature at about 250 ℃, and copper is restored from these composite oxides, thereby generates the initial mixture of metallic copper and molybdenum oxide.The second stage reduction is carried out under about 950 ℃ higher temperature at about 700 ℃, and makes molybdenum oxide be reduced into metal molybdenum, and this causes forming the two-phase particulate and copper is being wrapped by molybdenum mutually basically mutually.

This two stages reduction reaction is preferred, because CuMoO ₄The hydrogen reduction of phase because molybdic acid copper can be disproportionated into molybdic acid cuprous and become complicated, Cu ₆Mo ₄O ₁₅And Cu ₂Mo ₃O ₁₀Has relatively low fusing point (being respectively 466 ℃ and 532 ℃).When the initial period of hydrogen reduction, form these and be harmful to mutually, because it can melted powder and obstruction reduction process.It is found that and to prevent to form these liquid phases, i.e. CuMoO by utilizing thermodynamic probability ₄Copper in the base composite oxidate can be reduced under the temperature that is lower than the cuprous fusion point of molybdic acid.In first stage of reduction, adopt lower reduction temperature, eliminated the cuprous formation of eutectic melting point molybdic acid, and generate the initial mixture of Mo oxide and metallic copper.Though during the phase I hydrogen reduction, can form other molybdate of trace, Cu ₃Mo ₂O ₉And Cu ₆Mo ₅O ₁₈But these molybdates have high-temperature stability and can not cause any confusion.

In second stage, molybdenum oxide is reduced into metal molybdenum.Be used for the conventional method that Mo restores from its trioxide is usually directed to two steps of carrying out in the different temperatures scope.At first, MoO ₃Under 600-700 ℃, be reduced into MoO ₂, MoO then ₂Under 950-1100 ℃, be reduced into Mo.Yet at CuMoO ₄In the reduction of base oxide complex, that appears to is closely to contact caused catalytic action by just reducing the Cu that obtains with the Mo oxide.This causes MoO ₃→ MoO ₂The temperature of reduction step drops to 350-400 ℃, and MoO ₂The temperature of → Mo reduction step drops to 700-950 ℃.In addition, the existence of Cu phase causes molybdenum to be deposited on the Cu, and this has just suppressed the coalescent of copper particle and has grown up and make Cu be surrounded mutually by Mo gradually mutually.This mechanism is believed to be helpful in the size and the uniformity of the compound Mo-Cu particle of control.

After second reduction phase, as-reduced Mo-Cu composite powder may need passivation, to reduce the possibility of their oxidations and spontaneous combustion.Particularly, it is found that oxygen content is lower than the oxidisability and the pyrophorisity of the as-reduced Mo-Cu composite powder of 5000ppm, can be by after stove comes out, suppressing by 2 hours with this powder of nitrogen passivation 1.

The following examples have illustrated reduces described synthetic CuMoO ₄Base composite oxidate is to form Mo-Cu composite powder of the present invention.

Embodiment 5

The CuMoO that contains the relative copper content of 15wt.% ₄Base composite oxidate carries out the reduction reaction of phase I with the hydrogen that flows in experimental furnace.Approximately the oxide of 150g in the inconel boat, forms about 0.5 inch material bed deeply.Reduction temperature is 150,200,300 and 400 ℃.The speed that furnace temperature rises is 5 ℃/minute, and is incubated 4 hours under reduction temperature.Resulting product is screened to be-60 orders and carry out XRD analysis.

In this reduzate, do not find the cuprous (Cu6Mo of any low-melting molybdic acid ₄O ₁₅Or Cu ₂Mo ₃O ₁₀).In 150-200 ℃ of temperature range, find the Cu of trace in the resulting product of reduction ₃Mo ₂O ₉Phase and Cu ₆Mo ₅O ₁₈Phase.It is to begin under about 200 ℃ and finishing under about 300 ℃ that the reduction reaction of copper appears to.Main in 300 ℃ of products that restored down is Cu, MoO mutually ₂And MoO ₃Obviously the MoO that in this product, does not have reduction ₃Be quite active, and be exposed to the partially hydrated effect that is subjected to a kind of evolution of heat airborne the time.This just requires the product that reduction obtains under 300 ℃ will cool off in air about 20 to 30 minutes.In case cool down, described reduzate with grey black look color is just screened easily to be-60 orders.400 ℃ down main in the product that obtains of reduction be Cu and MoO mutually ₂In this case, the temperature of this product can not rise after being exposed to air.The product that reduction obtains under 400 ℃ lumps, and need pulverize so that it is become screenedly to be-60 purpose powder.

Embodiment 6

In having the large-scale hydrogen reduction furnace of three bringing-up sections, carry out and identical CuMoO used in embodiment 5 ₄The first stage of reduction of base composite oxidate.The oxide of heavily about 2kg forms about 0.5 inch material bed dark in the inconel boat.In experiment for the first time, the temperature of all bringing-up sections is set at 300 ℃.In experiment for the second time, the temperature of all bringing-up sections is set at 400 ℃.The time of staying of material in stove is about 4 hours.Final products are-60 orders for screening, and carry out XRD analysis.

After leaving stove, need in air, cool off about 30-45 minute by the temperature of testing the product that generates for the first time.Main in the product that is reduced mutually for Cu and MoO ₂The less important molybdenum trioxide by various hydrations constitutes.Figure 1 shows that the XRD figure case of this material.The profile of this product is similar in embodiment 5 at 300 ℃ of materials that obtain down.Main in the reduzate that is generated by experiment for the second time is Cu and MoO mutually ₂The vestige that also has the molybdenum trioxide of hydration.The profile of this product also is very similar in embodiment 5 at 400 ℃ of materials that obtain down.

Embodiment 7

To relative copper content at 5 synthetic CuMoOO in the scope of 40wt.% ₄Base composite oxidate carries out two stage hydrogen reduction reactions.Adopt with embodiment 5 in the same equipment, load-up condition and rate of rise in temperature.The temperature of reduction is 300 ℃ (phase I) and 700 ℃ (second stage), and is incubated 4 hours under each temperature.After under this stove being cooled to 200 ℃, the air-flow that passes this boiler tube is switched into nitrogen from hydrogen.Nitrogen stream remains to this stove always and is cooled to about 30 ℃.This just makes the Mo-Cu composite metal powder passivation of being reduced effectively.Becoming the color of the as-reduced powder of granule is the grey that is similar to pure Mo powder.In this Mo-Cu composite powder, can't see the vestige that copper exists.These powder are filtered into-60 orders and are analyzed its copper content, size distribution and surface area.In table 4, provided the result of different analyses.

Table 4

The copper content of measured Mo-Cu composite powder is usually than estimated value high about 2% to 3.5%.

Embodiment 8

Influence to the characteristic of resulting Mo-Cu powder experimentizes to the second stage reduction temperature.The CuMoO of initial material in embodiment 6, under 300 ℃, being reduced ₄Base composite oxidate (15wt.%).Except rate of rise in temperature is 20 ℃/minute, the reduction reaction of second stage adopts the condition the same with embodiment 7, and employing is carried out in the temperature of 700 ℃ to 950 ℃ scope.Carry out six restoring operations.Be-60 orders and analyzing through the Mo-Cu composite powder of reduction is screened.That analyzes the results are shown in the table 5.

Table 5

Usually, the powder agglomates that causes owing to sintering is along with the rising of reduction temperature increases.These experimental results show that in a large-scale reduction temperature, the size of the Mo-Cu composite powder through reducing and its bulk density can not increase monotonously along with the rising of temperature.In addition, along with significant sintering effect can appear in the increase of temperature, reduction of this itself its specific area of proof, and correspondingly, the particle diameter that calculates (BET particle diameter) increases.Equally, oxygen content is followed the tendency of this surface area and is reduced along with temperature.

Becoming the color of the as-reduced Mo-Cu composite powder of granule is the grey that is similar to pure Mo powder.In the Mo-Cu composite powder, can't see the vestige that Cu exists.In order to check the distribution of phase in this composite powder, to analyze them by sputtered neutral particle mass spectrometer (SNMS), and adopt second electronic imaging (SEI) and back scattered electron imaging (BEI) to come the metallographic sample on the pair cross-section to analyze by SEM (SEM).

It is that bulk by the limited diphase particles of the molybdenum grid that contains sintering constitutes that Mo-Cu composite powder of the present invention demonstrates, and wherein copper has been filled in the space in the grid.The distribution mutually of this uniqueness causes copper to be surrounded mutually by molybdenum basically mutually.As shown in the SEM microphoto, the shape of the particulate that these are limited be irregular and its size in the scope of about 0.5 to 1.5 μ m.This is relative with the particle diameter that is calculated from the BET surface area consistent.Fig. 3 (BEI) is the enlarged drawing of the shown limited particulate that goes out in the bulk shown in Fig. 2 (BEI), and shows that copper is mutually cingens by molybdenum mutually.This SNMS experimental result is consistent with the SEM observed result, and in SEM observed, they demonstrate did not have copper and these to distribute very evenly in powder on the surface of composite powder particulate.

Embodiment 9

Adopting relative copper content is the synthetic CuMoO of 15wt.% ₄Two stage reduction reactions of base composite oxidate are carried out large-scale experiment.In the stove the same, adopt under the condition of reduction temperature of same load-up condition and 300 ℃ and finish the first stage of reduction reaction with embodiment 6.End product is screened to carry out the second stage reduction in whole three sections for-60 orders and in temperature is 900 ℃ syllogic hydrogen reduction furnace.It is dark that approximately the 300g oxide forms about 0.5 inch bed in the inconel boat.The time of staying of material in the hot-zone of stove is about 4 hours.After leaving stove, the powder that is reduced is poured in the stainless steel funnel with nitrogen atmosphere to carry out surface passivation at once.The pyrophorisity of powder was just eliminated in surface passivation in 1 to 2 hour fully.Resulting Mo-Cu composite powder is screened for-60 orders and show and have following characteristic:

Size distribution: D ₉₀=47.0 μ m

D ₅₀＝17.9μm

D ₁₀＝2.8μm

Fei Xier particle size: 2.9 μ m

Specific area: 1.65m ²/ g

The particle diameter that calculates: 0.39 μ m

Oxygen content: 2700ppm

Bulk density: 1.26g/cm ³

Copper content: 15.06wt.%

Closely similar in the size of the powder that this embodiment makes and the powder in embodiment 8, under 900 ℃, made.Yet surface area and oxygen content are higher substantially, and the BET particle size is littler substantially.The limited particulate that this expression forms in this embodiment is littler than formed particulate in embodiment 8.

Mo-Cu composite powder fixed

During solid state sintering, form a kind of rigidity Mo framework, help obtaining the good dimensional stability of the Mo-Cu pseudo-alloy component made by P/M.Mo-Cu pseudo-alloy with firm Mo framework even under the situation that a large amount of liquid copper exist, also resists distortion during closely knit.High dimensional tolerance and do not have the distortion for the netted manufacturing of P/M of the thermal management component that is used for microelectronics and optoelectronic applications (fin), be even more important.

Compare with Mo-Cu composite powder of the present invention, the sintering of the mechanical blend of basic Mo and Cu powder is slowly.Demanding sintering temperature (up to 1650-1670 ℃) goes out closely knit of P/M with sintering from the metal dust that mixes, and this can cause copper to lose with the form of oozing out and evaporating from component.The loss of copper makes and is very difficult to obtain to be higher than 97% solid density (TD).(Fe, Co are very unfavorable with the caking power that improves these basic powder mixtures Ni), because this can reduce the thermal conductivity of Mo-Cu pseudo-alloy significantly to adopt sintering aid.

For Mo-Cu composite powder of the present invention, we find that copper content and Mo and Cu distribution mutually can influence the sintering condition of closely knit of powder significantly.Between copper content and closely knit sintering temperature, observe a kind of opposite relation.In detail, find that sintering temperature is from for copper content closely knit in the 26-40wt.% scope, 1050 ℃-1080 ℃ solid state sintering zone extends to for copper content closely knit in the 2-25wt.% scope, 1085 ℃-1400 ℃ the sintering zone in the presence of liquid copper.

Sintering under the situation that liquid copper exists comprises two steps of having imitated general permeating method, that is, and and the on-the-spot sintering of molybdenum framework and the internal penetration of liquid copper in this framework.Under the situation of 1083 ℃ of following fusions, by capillary osmosis by internal penetration advanced copper in the molybdenum framework at copper.Liquid copper is retained under capillary pressure in the molybdenum framework, removes from this molten copper at the oxygen of 1085 ℃-1100 ℃ following dissolving.Under the situation that liquid copper exists, also want this molybdenum framework of further sintering to finish the fixed of this pseudo-alloy.

But that the Mo-Cu composite powder can be consolidated into is as-reduced, become a granule or spray-dired flow regime.Can be with lubricator and/or binding agent and this powder, or during spray-drying, add to strengthen the fixed of powder.These materials can comprise for example zinc stearate, ethene distearyl acid amides or ethylene glycol.This Mo-Cu composite powder can be used in many common P/M consolidation methods, and for example machinery or isostatic pressing, injection moulding, belt be shaped, rolling and serigraphy is so that ceramic metallization.

Below be to be used for new closely knit of being made by Mo-Cu composite powder of the present invention dewaxed and the preferred process step of sintering:

1. according to the type of wax/binding agent, under about 200 ℃ to 450 ℃ temperature, make this closely knit blank dewaxing/unsticking;

2. under about 930 ℃ to 960 ℃ temperature, oxygen is removed from this closely knit blank;

3. go out roughly closely knit molybdenum framework at about 1030 ℃ to 1050 ℃ sintering temperature;

4 (a) are under about 1050 ℃ to 1080 ℃ temperature, and it is about 26wt.% closely knit to 40wt.% that solid state sintering goes out its copper content; Perhaps

4 (b). under about 1085 ℃ to 1400 ℃ temperature, under the situation that has liquid phase to exist, reburning, to bear its copper content be about 2wt.% closely knit to 25wt.%.

The shape of the Mo-Cu pseudo-alloy of producing according to this method, demonstration is oozed out without any copper, and have extraordinary shape retention and high sintered density (approximately 97%-99%TD) and tiny pseudo-alloy microstructure (Mo crystal grain at about 1 μ m in the scope of 5 μ m; The copper zone concentrates on about 2 μ m in the scope of 15 μ m; ).

Embodiment 10

From the Mo-Cu composite powder of among embodiment 9, making (15wt.%Cu), prepare Mo-15Cu pseudo-alloy sample.Fixed in order to improve, sneak into the ethene distearyl acid amides of 0.5wt.% to this powder, a kind of by FairLawn, the Lonza of New Jersey, the trade mark that Inc. produces is the kollag of Acrawaxc.This powder is become green density by mechanical compaction under 70ksi be the flat sample (33.78 * 33.78 * 1.62mm) of about 62%TD.Transfer to equably on the sample in order to ensure heat during dewaxing and sintering, in fine aluminium sand, handle these samples.In experimental furnace, in the hydrogen that flows, finish heat treatment with aluminum pipe.In order to prevent that pipe from splitting under the effect of thermal stress, heat/cool rates will be restricted to 2 ℃ of part clocks.The sintering circulation comprises: be incubated 1 hour to remove the oxygen on powder lubricant and surface under 450 ℃ to 950 ℃ temperature; Be incubated 1 hour so that on-the-spot sintering goes out the molybdenum framework down at 1040 ℃; 1100 ℃ down insulation 2 hours from molten copper, remove oxygen and these samples of presintering of dissolving so that allow liquid copper at the internal penetration of molybdenum framework; And under 1230 ℃, be incubated 2 hours so that finally make these samples fixed.The temperature of back is according to do not cause the highest pseudo-alloy density that obtains under the situation that copper oozes out by excessive sintering molybdenum framework, determines by experience.

In the operation (every operation has three samples) of several successive, as-reduced Mo-15Cu powder demonstrates extraordinary caking power, do not have copper to ooze out and closely knit of sintering has good shape retention.Average linear contraction is 15%, and the mean value of sintered density and conductance is respectively in the scope of 98.8-99.0%TD and 36.6-36.7%IACS.

The thermal conductivity of these sintered samples is to determine in the correlation that goes out of electric conductivity from the Mo-Cu pseudo-alloy and the report between the thermal conductivity.For a kind of Mo-15Cu pseudo-alloy of infiltration, 51.0n Ω m (equaling the electric conductivity of 33.8%IACS) is corresponding to the thermal conductivity of 166W/mK.For the sample of making by the Mo-15Cu composite powder, measure the increases of 1.085 letters in electric conductivity, the thermal conductivity of sample is risen to roughly be higher than about 180W/mK.

In Fig. 4, demonstrate the SEM microphoto of the section of one of them Mo-15Cu pseudo-alloy sample.The molybdenum framework of this pseudo-alloy is formed by circular, highly interconnected crystal grain almost, it distributes, order and size under the situation that liquid phase exists, be subjected to dividing into groups again and limited influence of growing up.The size of crystal grain is in about 1 micron to 4 microns scope.The crystal grain of circular interconnection shows, under the situation that liquid phase exists, and the sintering structure that constitutes by the particulate reorganization and by under sintering temperature, by the adaptability of the small grain shape that dissolubility provided of molybdenum in liquid copper.The average-size of Cu is in about 2 microns to 15 microns scope.Before sintering reduced powder remove granule, expection can improve the uniformity of the microstructure of P/M pseudo-alloy basically.

Embodiment 11

From the Mo-Cu composite powder of among embodiment 7, making (40wt.%Cu), prepare Mo-40Cu pseudo-alloy sample.Adopt and suppress these samples with embodiment 10 identical conditions.But higher copper content can improve the briquettability of these samples basically, and the green density of these samples is 73%TD.As at embodiment 10, final fixed temperature is according to do not cause the highest pseudo-alloy density of acquisition under the situation that copper oozes out by excessive sintering molybdenum framework, determines by experience.Verified, high copper content is limited in final consolidation temperature on 1065 ℃, therefore brings it into the solid state sintering zone.

In two continuous operations (every operation has three samples), as-reduced Mo-40Cu powder demonstrates extraordinary caking power, and closely knit of sintering has good shape retention.Average linear shrinkage is 9%, and the mean value of sintered density and conductance is respectively in the scope of 97.8-97.9%TD and 50.7-51.0%IACS.With comparing of Mo-15Cu sample among the embodiment 10, lower linear shrinkage can be explained by the following fact: the Mo-40Cu sample is pressed into higher green density and is bonded to lower sintered density.

In Fig. 5, demonstrate the SEM microphoto of the section of a Mo-40Cu pseudo-alloy sample.By the microphoto in the Figure 4 and 5 relatively, can obviously find out solid state sintering and at the greatest differences between the sintering under the situation that liquid phase exists.The molybdenum framework that goes out at 1040 ℃ of following sintering has only very little variation during 1065 ℃ of following sintering.The Mo particulate string list that its size and geometry are not influenced by sintering almost is bright, does not have particulate reorganization and size adaptability sintering mechanism, and these phenomenons only just have in having the situation of liquid phase.Therefore, the microstructure of the pseudo-alloy of solid state sintering is than will more not having order (more Mo particulate string, bigger Cu zone) in the microstructure that has the pseudo-alloy that sintering goes out under the situation of liquid phase.Yet the high sintering density meter of the material of solid state sintering is bright, the as-reduced Mo-40Cu powder before sintering separate the uniformity that coalescent effect can improve the microstructure of P/M pseudo-alloy substantially.

Though shown and preferred implementations of the present invention be described, but for those those of ordinary skills, it is evident that, under the situation that does not break away from the scope of the present invention that limits by the appended claims, can make various changes and improvements the present invention.

Claims (12)

1. one kind prepares CuMoO ₄The method of base combined oxidation powder comprises:

(a) form the mixture of molybdenum oxide and cupric oxide, molybdenum oxide conduct oneself with dignity ammonium molybdate, metamolybdic acid ammonium or molybdenum dioxide; And

(b) under a certain temperature, fire this mixture time enough, to form CuMoO ₄Base composite oxidate.

2. the process of claim 1 wherein and join in this mixture surpassing the cupric oxide of stoichiometry up to 4wt.%.

3. the process of claim 1 wherein that cupric oxide is selected from cuprous oxide or cupric oxide.

4. the process of claim 1 wherein CuMoO ₄Base composite oxidate consist of CuMoO ₄+ xMoO ₃, wherein x is from 29 to 0.

5. the process of claim 1 wherein and under about 650 ℃ to 750 ℃ temperature, fired this mixture about 5 hours.

6. the method for claim 5 wherein joins in this mixture surpassing the cupric oxide of stoichiometry up to 4wt.%.

The method of 7 claims 6, wherein cupric oxide is selected from cuprous oxide or cupric oxide.

8. the method for claim 5, wherein CuMoO ₄Base composite oxidate consist of CuMoO ₄+ xMoO ₃, wherein x is from 29 to 0.

9. method for preparing the Mo-Cu composite powder comprises:

(a) form the mixture of molybdenum oxide and cupric oxide, molybdenum oxide conduct oneself with dignity ammonium molybdate, metamolybdic acid ammonium or molybdenum dioxide;

(b) under a certain temperature, fire this mixture time enough, to form CuMoO ₄Base combined oxidation powder;

(c) CuMoO ₄Base combined oxidation powder reduction with the original mixture of the oxide that forms a kind of metallic copper and molybdenum, and can not form the cuprous phase of low-melting molybdic acid; And

(d) under a temperature, make this original mixture reduction time enough, so that molybdenum oxide is reduced into metal molybdenum.

10. the method for claim 9 is wherein carried out the reduction of described step (c) under about 250 ℃ to 400 ℃ temperature.

11. the method for claim 10 is wherein carried out the reduction of described step (d) under about 700 ℃ to 950 ℃ temperature.

12. the method for claim 9, wherein low-melting molybdic acid is cuprous to be Cu mutually ₆Mo ₄O ₁₅And Cu ₂Mo ₃O ₁₀

13. the method for claim 9, wherein after the reduction of step (d) in nitrogen to described Mo-Cu composite powder hinge.

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