CN1223706C - Chemical coppering process for non-aqueous system hydrogen storage alloy powder - Google Patents

Abstract

The present invention discloses a chemical copper plating technology of hydrogen storing alloy powder of a non-water system, which belongs to the chemical plating technology of chemical hydrogen storing alloy powder. The chemical copper plating technology of a non-water system of the present invention uses organic polar substances for replacing part of water to carry out chemical copper plating, wherein the volume percentage content of the organic polar substances is from 5 to 80%, and the organic polar substances are substances with hydrophilic polar functional groups of a hydroxyl group, a carboxyl group, an amino group, etc. The technology effectively inhibits the occurrence of alloy corrosion in the solution and copper dismutation reaction and has the advantages of good plating effect, high corrosion resistance after plating operation, uniform plating, simple technology, etc. The technology is suitable for plating hydrogen storing alloy powder of AB type, A2B type, AB2 type and AB5 type and is particularly suitable for plating alloy powder which can be corroded easily.

Description

The chemical-copper-plating process of non-aqueous system Mg base hydrogen bearing alloy powder

Technical field

The present invention relates to a kind of chemical-copper-plating process of non-aqueous system hydrogen storing alloy powder, belong to hydrogen storing alloy powder chemical plating Technology.

Background technology

Along with the continuous expansion of population and the high speed development of human society, cause the sharp increase of energy consumption, many energy that we relied on, 21 century all will face exhaustion.And hydrogen, because its aboundresources, energy density height, advantage such as pollution-free, shown good prospects for application, and as the carrier of hydrogen, hydrogen storage material then is hydrogen energy source to be applied to the key of going in the practice, therefore, it is imperative to develop a kind of hydrogen storage material of excellent property.

Advantages such as in the hydrogen storage media of having developed at present, magnesium and alloy thereof be with its high hydrogen storage, and low-gravity is cheap, and is pollution-free cause people's extensive concern day by day.But Magnuminium but has three serious weakness as hydrogen storage material: the one, and magnesium and alloy thereof are easily oxidized in air, and the oxide film that the surface generates hinders the activation and the suction of alloy to put hydrogen; Perishable in alkali lye, generate unsound Mg (OH) ₂, solution is seen through, continue corrosion, jeopardize the body phase; The 2nd, the hydride of magnesium and alloy thereof is too stable, and below 250 ℃, the hydrogen process is put in the suction that does not take place on any practical significance, even more than 250 ℃, also will activate repeatedly repeatedly could reversibly inhale and put hydrogen; The 3rd, the suction hydrogen desorption kinetics poor performance of magnesium and alloy thereof.

Electroless copper is a kind of efficient and simple method of modification hydrogen storage alloy performance, some hydrogen storage alloys contact or are easy to corrosion in the aqueous solution with aqueous vapor, the surface generates oxyhydroxide, hydrogen storage property to alloy produces detrimentally affect, cause the alloy hydrogen-storage amount to be decayed rapidly, so the etching problem of hydrogen storage alloy has caused people's attention.Present document does not also have in the non-aqueous system the report of hydrogen storing alloy powder electroless plating aspect, generally all is to start with from the stablizer aspect, studies the influence of the interpolation of a small amount of organic reagent to bath stability and sedimentation velocity.Traditional be in the chemical-copper-plating process of solvent with water, when using formaldehyde as reductive agent, Cu in the plating process ²⁺Easily be reduced and generate Cu ₂O, the Cu of generation ⁺Disproportionation reaction easily taking place, generate small copper particle, plating bath is decomposed fast, thereby has a strong impact on the performance of copper-plated effect and plating back alloy.

Summary of the invention

The present invention aims to provide a kind of chemical-copper-plating process of non-aqueous system Mg base hydrogen bearing alloy powder.The non-aqueous system chemical-copper-plating process, it can suppress Cu effectively ⁺The generation of ion disproportionation reaction has improved the copper facing effect of plating alloy, makes plating back alloy powder that better intensity, toughness, heat conductivity and erosion resistance be arranged.

The chemical-copper-plating process of above-mentioned non-aqueous system Mg base hydrogen bearing alloy powder comprises the steps:

1) chemical-copper-plating process of this non-aqueous system hydrogen storing alloy powder is a solvent with the system of water-polar organic material composition, wherein the polar organic material is the organic substance that has hydrophilic functional groups such as hydroxyl, carboxyl, amino, and the shared volumn concentration of polar organic material is between 5-80%;

2) in above-mentioned solvent, press CuSO ₄5H ₂O is 10～40g/L, K ₄[Fe (CN) ₆] 3H ₂O is that 15～35mg/L, HCHO are 10～45ml/L preparation plating bath;

3) in above-mentioned plating bath, add 200～400 purpose alloy powders by the amount of 0.05～0.4g/L, low whipping speed is that 250～400 commentaries on classics/min, temperature are to react 10～30min under 25～45 ℃, pH=12～13.5 conditions;

4) will be set by step 3) gained plating back alloy powder carries out suction filtration, can obtain the hydrogen storing alloy powder of plated copper after the seasoning.

Non-aqueous system chemical-copper-plating process of the present invention is because the adding of polar organic matter matter has suppressed Cu greatly ⁺The generation of disproportionation reaction, thereby reduced Cu ₂The generation of O, the erosion resistance of raising hydrogen storing alloy powder strengthens conduction, heat conductivility, is a kind of good plating technic.

Description of drawings

Fig. 1 is not for containing methyl alcohol and containing copper-plated Mg in 40% methanol solution _1.85Mm _0.15The potentiostatic polarization curve figure of Ni alloy (25 ℃).

Fig. 2 is the Mg behind the electroless copper in the plating bath that contains 40% methyl alcohol _1.85Mm _0.15Ni alloy powder SEM figure.

Fig. 3 is the XPS collection of illustrative plates of alloy powder surface copper behind the electroless copper in the plating bath that contains 60% methyl alcohol.

Embodiment

The present invention is described further below by example:

Embodiment 1:

With the plating bath of 100ml (wherein methyl alcohol accounts for 20%) with 2g CuSO ₄5H ₂O and 5.95gEDTA are dissolved in the 250ml beaker, get 200～400 purpose Mg _1.85Mm _0.15Ni alloy powder 1g, K ₄[Fe (CN) ₆] 3H ₂O is 2.5mg, makes reductive agent with 2mlHCHO, and stirring velocity is that 350 commentaries on classics/min, pH value are 13,40 ℃ of temperature of reaction, behind the reaction 15min, reacted alloy powder is carried out suction filtration, and natural airing packs, and is standby.

Will be by the above-mentioned copper-beryllium powder mould tablet forming that obtains, non-test surfaces is coated Resins, epoxy, carries out electro-chemical test in 5MKOH, and the potentiostatic polarization curve of gained and the fitting data of alternating-current impedance see Table 1.

Table 1 Mg _1.85Mm _0.15The Ni alloy is not containing methyl alcohol and is containing the electrochemical parameter (25 ℃) of copper facing rear electrode in the plating bath of 20% methyl alcohol

Methanol content	i corr/mA·cm 2	b c/mV	R 1/Ω·cm 2	R 2/Ω·cm 2
					0	9.6	107	2.87	18.84
20％	6.7	150	2.71	13.77

i _CorrBe corrosion electric current density; b _cBe negative electrode Tafel slope: R ₁Resistance for the diffusion reaction of hydrogen; R ₂Be reaction resistance

With copper-plated alloy phase ratio in the plating bath that does not contain methyl alcohol, copper-plated alloy in containing 20% methyl alcohol plating bath has reduced corrosion electric current density, has increased the Tafel slope of cathode hydrogen evolution, has reduced the resistance of alloy, thereby has strengthened the electro catalytic activity of alloy.One tangible oxidation peak appears in the potentiostatic polarization curve after the non-aqueous system copper facing about-0.4V, it can be belonged to the dissolving of copper.The existence at copper dissolution peak explanation coats that the copper layer is just destroyed about-0.4V to be fallen; the current potential upper limit in the general Magnuminium electrode charge and discharge working cycle can not compare-the 0.4V corrigendum; so coating the copper layer in this case can be not destroyed; can play the effect of protective membrane; slow down the corrosion of inner alloy, thereby improved the erosion resistance of alloy greatly.

Embodiment 2:

With the plating bath of 100ml (wherein methyl alcohol accounts for 40%) with 1.5g CuSO ₄5H ₂O and 5.0gEDTA are dissolved in the 250ml beaker, get 200～300 purpose Mg _1.85Mm _0.15Ni alloy powder 1g, K ₄[Fe (CN) ₆] 3H ₂O is 2.0mg, makes reductive agent with 2.5mlHCHO, transfers that stirring velocity is that 380 commentariess on classics/min, pH value are 12.5,35 ℃ of temperature of reaction, react 25min after, reacted alloy powder is carried out suction filtration, natural airing packs, and is standby.

Will be by the above-mentioned copper-beryllium powder mould tablet forming that obtains, non-test surfaces is coated Resins, epoxy, carries out electro-chemical test in 5MKOH, and the fitting result of potentiostatic polarization curve Fig. 1 and alternating-current impedance spectrogram sees Table 2.The above-mentioned copper-beryllium powder that obtains is carried out the SEM test, and gained the results are shown in Figure 2.

Table 2 Mg _1.85Mm _0.15The Ni alloy is not containing methyl alcohol and is containing the electrochemical parameter (25 ℃) of copper facing rear electrode in the plating bath of 40% methyl alcohol

Methanol content	i corr/mA·cm 2	b c/mV	R 1/Ω·cm 2	R 2/Ω·cm 2
					0	9.6	107	2.87	18.84
40％	5.6	154	3.04	22.25

With copper-plated alloy phase ratio in the plating bath that does not contain methyl alcohol, copper-plated alloy in containing 40% methyl alcohol plating bath has reduced corrosion electric current density, has increased the Tafel slope of cathode hydrogen evolution, thereby has improved the erosion resistance of alloy.Scheme as can be seen from the SEM that plates 7000 times of back alloy powder amplifications, the copper layer of plating is evenly fine and close, and coating surface is smooth mellow and full.

Embodiment 3:

With the plating bath of 100ml (wherein methyl alcohol accounts for 60%) with 2.2g CuSO ₄5H ₂O and 6.5gEDTA are dissolved in the 250ml beaker, get 200～400 purpose Mg _1.85Mm _0.15Ni alloy powder 2.0g, K ₄[Fe (CN) ₆] 3H ₂O is 3.1mg, makes reductive agent with 2.8mlHCHO, and stirring velocity is that 400 commentaries on classics/min, pH value are 12.8,45 ℃ of temperature of reaction, behind the reaction 19min, reacted alloy powder is carried out suction filtration, and natural airing packs, and is standby.

Will be by the above-mentioned copper-beryllium powder mould tablet forming that obtains, non-test surfaces is coated Resins, epoxy, carries out electro-chemical test in 5MKOH.The above-mentioned copper-beryllium powder that obtains is carried out the XPS test, and gained the results are shown in Figure 3.

From the potentiostatic polarization curve test result, carrying out the alloy powder of plated copper in 60% methyl alcohol compares with the alloy powder that does not carry out plating in methyl alcohol, reduced corrosion potential, improved the Tafel slope of negative electrode, thereby improved the corrosion resistance of alloy, and for not too big change of corrosion electric current density.From XPS result, existing a little copper is oxidized to CuO in the plating process, and Cu peak and CuO peak remain basically stable, and we think that the appearance of oxide compound of copper may be relevant with the plating overlong time.

Claims (1)

1, a kind of chemical-copper-plating process of non-aqueous system Mg base hydrogen bearing alloy powder, this alloy is Mg _1.85Mm _0.15Ni, the system of forming with water-polar organic material is a solvent, and wherein the polar organic material is the organic substance that has hydroxyl, carboxyl, amino hydrophilic functional group, and plating bath contains CuSO ₄5H ₂O is characterized in that it comprises the steps:

1) the shared volumn concentration of said polar organic material is between 5-80%;

2) in above-mentioned solvent, press CuSO ₄5H ₂O is 10～40g/L, K ₄[Fe (CN) ₆] 3H ₂O is that 15～35mg/L, HCHO are 10～45ml/L preparation plating bath;

3) in above-mentioned plating bath, add 200～400 purpose alloy powders by the amount of 0.05～0.4g/L, low whipping speed is that 250～400 commentaries on classics/min, temperature are to react 10～30min under 25～45 ℃, pH=12～13.5 conditions;

4) will be set by step 3) gained plating back alloy powder carries out suction filtration, can obtain the hydrogen storing alloy powder of plated copper after the seasoning.

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