Preparation method of tungsten/copper layer composite material based on surface nanocrystallization of tungsten sheet

A composite material and nano-technology, which is applied in the field of the preparation of mutually insoluble metal tungsten/copper layered composite materials, can solve the problems of destroying the consistency of the system components, unable to use large-scale, difficult to control the coating, etc., and achieve the production cost. Inexpensive, easy to operate, good binding effect

Active Publication Date: 2018-09-25

TIANJIN UNIV

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AI-Extracted Technical Summary

Problems solved by technology

Traditional connection/composite technologies (diffusion welding, brazing, etc.) often need to introduce third-party metals as intermediate layers, such as Ti, Ni, etc., which will destroy the consistency of system components, easily form hidde...

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Method used

The tungsten sheet after the above-mentioned anodic oxidation treatment is placed on Al2O3 Ceramic substrate is put into annealing furnace and carries out reduction annealing deoxidation under hydrogen atmosphere, annealing temperature is 700 ℃, and soaking time is 3h, and temperature curve is as shown in Figure 1 : Heat up to 250°C at a rate of 5°C/min, hold at 250°C for 10 minutes, then heat up to 700°C at a rate of 5°C/min, hold at 700°C for 3 hours, then cool to room temperature with the furnac...

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Abstract

A preparation method of a tungsten/copper layer composite material based on surface nanocrystallization of a tungsten sheet is disclosed. The method includes performing surface pretreatment on the tungsten sheet; performing two steps of anodic oxidation and hydrogen reduction annealing in order to obtain a tungsten sheet having a deeply deoxygenated surface nanometer porous structure; electroplating the surface of the tungsten sheet having the nanometer porous structure with copper; and finally subjecting a tungsten/copper electroplated sample to high-temperature diffusion annealing to obtainthe tungsten/copper layer composite material. During preparation, the nanometer porous structure on the surface of the tungsten sheet can increase the contact area and improve surface activity, and can play a role of mechanically meshing a copper layer. A thermal shock method and a cross cut method are adopted to detect whether the copper metal layer shows peeling and shedding phenomena or not. The preparation method has characteristics of a simple process, a stable and pollution-free electroplating solution, a high connection efficiency, a low production cost, and good repeatability, can prepare a tungsten/copper material having a complex shape and based on the inner surface of a workpiece, avoid influences of metal middle layers on material performance, and facilitate industrial application of the tungsten/copper composite material.

Application Domain

Surface reaction electrolytic coating

Technology Topic

Anodic oxidationTungsten +8

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Examples

Experimental program(6)

Example Embodiment

[0029] Example 1: Preparation of a tungsten/copper layered composite material based on the surface nanocrystallization of a tungsten sheet, the steps are as follows:

[0030] Step 1. Pre-treatment of tungsten sheet:

[0031] Take the 25×20×0.1mm tungsten sheet (purity ≥99.95wt%) as the sample, and use 800#, 1000# and 1500# metallographic sandpaper to smooth the sample. Each time the sandpaper is changed, the sample is polished. Rotate the direction by 90°, until the previous polishing traces completely disappeared, and finally there are only 1500# sandpaper polishing traces on the surface of the tungsten sheet; after polishing, polish the polished tungsten sheet with 0.5μm diamond polishing agent, and then separate them in acetone and isocyanate. Ultrasonic cleaning in propanol and methanol for 10 minutes to achieve the purpose of degreasing, and finally ultrasonic cleaning in absolute ethanol and ultrapure water for 10 minutes. After cleaning, put it in a vacuum drying oven for 24 hours, during which the vacuum degree is 10 -1 Pa, the drying temperature is 25°C.

[0032] Step two, two-step anodizing treatment:

[0033] A platinum sheet (purity ≥99.99%) is used as a cathode, and the pre-treated tungsten sheet is used as an anode, and two-step anodization is performed in an electrolyte containing fluoride ion and hydrogen ion to form a nanoporous oxide layer on the surface of the tungsten sheet. Among them, the electrolyte is a mixed solution of sodium fluoride (NaF) and hydrofluoric acid (HF). The configuration of the mixed solution is: add 0.5 g of sodium fluoride (NaF) to 250 mL of ultrapure water, stir to dissolve, and then add 1.66mL of hydrofluoric acid (HF, purity ≥40%), add ultrapure water to make the volume to 500mL, mix well, and obtain the electrolyte, that is, the concentration of NaF in the electrolyte is 0.2wt.% by weight, and the volume percentage of HF is concentration. It is 0.3%, and the pH is between 2 and 3;

[0034] The anodic oxidation voltage and time are as follows: first oxidize at 60V for 60min, then quickly reduce the voltage to 40V within 1s, and continue oxidation for 60min, the electrode spacing is 3cm, and the temperature is room temperature. After finishing, rinse the anodized tungsten sheet with ultrapure water and put it in a vacuum drying oven for 24 hours, during which the vacuum degree is 10 -1 Pa, the drying temperature is 25°C.

[0035] Step three, hydrogen reduction deoxygenation treatment:

[0036] Place the above anodized tungsten sheet in Al 2 O 3 The ceramic substrate is placed in an annealing furnace under hydrogen atmosphere for reduction annealing and deoxidation. The annealing temperature is 700℃, the holding time is 3h, and the temperature curve is as follows figure 1 Shown: heating up to 250°C at a rate of 5°C/min, holding at 250°C for 10 minutes, then heating up to 700°C at a rate of 5°C/min, holding at 700°C for 3 hours and then cooling to room temperature in the furnace. Take it out after cooling to obtain a tungsten sheet with a deep deoxidized surface nanoporous structure. The surface morphology is shown figure 2 , It can be seen that the nanopores are regular in shape and uniformly distributed, with an average pore diameter of about 68nm; in addition, the surface activity of tungsten has also been improved, such as image 3 As shown, the tungsten sheet with a deep deoxidized surface nanoporous structure has a lower hydrogen evolution starting potential.

[0037] Step 4. Copper electroplating:

[0038] First, prepare the cyanide-free copper electroplating solution of EDTA system with copper sulfate as the main salt: add 25g copper sulfate, 170g disodium ethylenediaminetetraacetic acid (EDTA), 20g sodium potassium tartrate, 4g potassium nitrate and 40g sodium hydroxide into the super Stir and dissolve in pure water, make a constant volume of 1L, magnetically stir for 12 hours and mix evenly, and control the pH between 12-13.

[0039] An oxygen-free copper plate (100×100×1mm, purity ≥99.95wt%) is used as an anode, and the tungsten sheet with a surface nanoporous structure obtained in step 3 is used as a cathode, and DC electroplating is performed in the above-mentioned non-cyanide copper electroplating solution. During electroplating, the cathode current density is 1A/dm 2 , The electroplating time is 30min, using water bath heating, the bath temperature is controlled at 40℃, and the electrode spacing is 10cm. After the electroplating, the tungsten/copper electroplating sample is rinsed with ultrapure water and dried for later use.

[0040] Step 5. High temperature diffusion annealing:

[0041] The tungsten/copper electroplating sample obtained in step 4 is annealed at a high temperature in an argon atmosphere, the annealing temperature is 980℃, the holding time is 3h, and the temperature curve is as follows Figure 4 Shown: heat up to 250°C at a rate of 5°C/min, hold at 250°C for 10 minutes, then heat up to 980°C at a rate of 5°C/min, hold at 980°C for 3 hours, then take it out after being cooled to room temperature in the furnace. Tungsten/copper layered composite material.

[0042] Test and characterize the tungsten/copper layered composite material obtained in Example 1:

[0043] (1) Microstructure test results

[0044] figure 2 It is a SEM photo of the surface morphology of the metal layer with nanoporous structure on the deep deoxidized surface. It can be seen that the nanopores are regular in shape and evenly distributed, with an average pore diameter of about 68nm;

[0045] Figure 5 It is the SEM photo of the morphology of the copper layer on the surface of the tungsten/copper layered composite material. The figure shows that the copper metal layer is dense, the grain size is uniform, and the porosity is low;

[0046] Image 6 It is an SEM photograph of the cross-sectional morphology of the tungsten/copper layered composite material. The connection is flat without obvious defects such as cracks and holes. The thickness of the copper metal layer is about 4.8μm, and the copper layer is tightly combined with the substrate.

[0047] (2) Tungsten surface activity test results

[0048] The activity test of the nanoporous metal layer on the surface of tungsten metal was carried out on the PARSTAT 2273 electrochemical test system. The traditional three-electrode system was adopted, that is, the tungsten sheet with the nanoporous structure on the surface of deep deoxidation was used as the working electrode, the platinum sheet was the counter electrode and the saturated glycerin The mercury electrode is a reference electrode, and the electrolyte is 0.5MH 2 SO 4 Solution.

[0049] image 3 Shown is the hydrogen evolution polarization curve of a tungsten sheet with a deep deoxidized surface nanoporous structure and a pure tungsten sheet without any treatment, when the current density is 10mA/cm 2 It can be seen from the figure that the hydrogen evolution initiation potential of pure tungsten flakes is higher, about 490mV, while the tungsten flakes with deep deoxidized surface nanoporous structure have a lower hydrogen evolution initiation potential of about 308mV. Small means that the smaller the energy required to produce hydrogen, the higher the surface activity.

[0050] (3) Test result of bonding force of copper metal layer

[0051] According to the national standard GB/T 5270-1985 metal coating (electrodeposition layer or chemical deposition layer) adhesion strength test method on the metal substrate, the tungsten/copper layered composite material is cross-cut test and thermal shock test for qualitative inspection The bonding force between the copper layer and the surface of the base tungsten sheet is the interface bonding force of the composite material.

[0052] Cross-cut test: Use a hard steel scoring knife with an acute angle of 30° to scribe 10×10 square grids with a side length of 1mm. When scribing, apply sufficient pressure so that the scoring knife can cut through the copper once When the layer reaches the base metal tungsten, use 3M 600 to test the tape to stick to observe whether the copper metal layer in the grid falls off. If it does not fall off, it is qualified, and if it falls off, it is unqualified.

[0053] Thermal shock test: Put the sample of the tungsten/copper layered composite material in a 250℃ resistance furnace and heat it for 1h, then take it out and put it in room temperature water (25℃) to cool down suddenly, cycle 3 times, and observe whether there is any copper metal layer The phenomenon of peeling and shedding, no peeling and no shedding is qualified, and peeling and shedding is unqualified.

[0054] Figure 7 Shown is a photo of the surface morphology of the sample after the cross-cut test. From the figure, it can be seen that the copper metal layer does not fall off. Figure 8 It is a photo of the surface morphology of the sample after the thermal shock test. The copper metal layer has no peeling or peeling phenomenon, and there is no difference in appearance from the copper layer before the test. It can be seen that the copper layer and the tungsten matrix have good bonding strength, and the composite material has a good Interface bonding strength.

Example Embodiment

[0055] Example 2. Preparation of a tungsten/copper layered composite material based on the surface of a tungsten sheet. The steps are basically the same as that of Example 1, except that: in step 4, the plating time is 45 minutes, and the final tungsten/copper layered composite The surface of the composite material is smooth and bright, and the thickness of the copper metal layer is about 6.2μm. After the cross-cut test and the thermal shock test, the copper metal layer has no peeling or peeling phenomenon, and the bonding force with the tungsten matrix is good.

Example Embodiment

[0056] Example 3. Preparation of a tungsten/copper layered composite material based on the surface nanocrystallization of a tungsten sheet. The steps are basically the same as in Example 1, except that: in step 4, the plating temperature is controlled at 60°C, and the final tungsten/copper The surface of the layered composite material is smooth and bright, and the thickness of the copper metal layer is about 5.2 μm. After the cross-cut test and the thermal shock test, the copper metal layer has no peeling or peeling phenomenon, and the bonding force with the tungsten matrix is good.

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PUM

Property	Measurement	Unit
Average pore size	68.0	nm
Thickness	5.2	µm
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

High specific surface area
Simple ingredients

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Good stability Strong combination Simple and efficient operation Good repeatability Reduce manufacturing cost Wide applicability Thermal shock Electroplating Anode Pollution Nanotechnology Repeatability

Preparation method of tungsten/copper layer composite material based on surface nanocrystallization of tungsten sheet

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Example Embodiment

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Example Embodiment

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Description & Claims & Application Information

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