CN100424223C - A kind of copper or copper alloy surface spark strengthening method - Google Patents

Abstract

The invention relates to a method for conducting electric spark deposition treatment on the surface of copper or copper alloy. Copper or copper alloy is used as the deposition object, and the corresponding electrodes are used for deposition treatment. Under the protection of argon or helium or a mixed gas of argon and helium, EDM equipment is used for deposition treatment. During the deposition process, the output power 400~1300W, output voltage 60V~80V, discharge frequency 100~700Hz; protective gas flow rate 18~30L/min, specific deposition time 3~15 minutes. First of all, the present invention does not need to use complex equipment such as vapor deposition and vacuum sintering; it does not cause thermal damage to copper, and can be deposited repeatedly. It can be completed by hand-held operation, and the heat-affected zone is narrow or no heat-affected zone; and the method does not require preheating before deposition and annealing after deposition.

Description

A kind of copper or copper alloy surface spark strengthening method

technical field

The invention belongs to a metal surface treatment method, in particular to a method for performing electric spark deposition treatment on the surface of copper or copper alloy (mainly the material of a red copper drug-type cover).

Background technique

At present, red copper is used as the material of the drug-type cover. This is because the density of copper is relatively high, and it has a certain strength. It has better plasticity under super-dynamic load.

The composition of the drug-type cover copper plate is an important factor affecting its quality. The existence of oxygen element in the copper plate is harmful. It exists in the form of Cu ₂ O. When the oxygen content is high, the cuprous oxide is distributed in a band shape, which seriously reduces the plasticity of the copper plate and increases the brittleness, resulting in the stamping and spinning performance of the copper plate. reduce. The crystallographic orientation of the copper plate is also another important factor affecting the medicine mask. The metal material will form a certain crystallographic orientation after rolling, and the distribution of preferred orientation is also called texture. The texture shape directly affects the subsequent cold working, and the grain size of the copper plate. The forming of the drug-type cover requires that the copper plate has a good combination of strength and plasticity. Fine grains can increase the strength, and large grains are beneficial to plasticity. If the strength of the hard copper plate is too high, the corresponding grain size should be relatively large, and if the strength of the soft copper plate is small, the corresponding grain size should be relatively small, so as to achieve the best combination of strength and plasticity.

At present, there are two different directions in the research of armor-piercing ammunition cover materials in the world: pure metal and multi-phase composite materials. Both of these methods are trying to improve the jet density of the medicine mask. Pure metal liner materials mainly include Cu, Ni, Mo, W, Ti, etc. The multi-phase composite drug-type cover mainly includes W-Cu, Re-Cu, Ta-Cu and so on. However, during the processing of Mo, W, and Ti in single-phase pure metal materials, the processing technology is difficult to realize, and the cost is too high, which is not suitable for my country's national conditions. The drug-type cover of multi-phase composite material has been studied abroad, especially the Cu-W drug-type cover material. The United States, France, Israel and other studies on Cu-W drug-type cover materials show that: under the condition of 3 times the caliber explosion height, its armor penetration depth can be increased by about 30% compared with pure copper.

The jet flow formed by the metal of the new liner has a high specific gravity, and its penetration performance is better than that of the copper liner. However, it is not easy to guarantee the processing, dimensional accuracy, and uniformity of the structure, and the processing and manufacturing of the liner should be reduced as much as possible. cost. Therefore, the copper drug-type cover still accounts for a large proportion.

Contents of the invention

Aiming at the above current situation, the present invention provides a method for strengthening the surface of copper or copper alloy (mainly drug-type cover copper) by electric spark, and depositing the copper drug-type cover, thereby increasing the quality of the drug-type cover copper and improving the quality of the copper drug-type cover. Cover performance.

Technical scheme of the present invention is:

A copper or copper alloy surface electric spark strengthening method, the specific steps are as follows:

(1) The corresponding electrode is used for deposition treatment, the electrode adopts the self-rotating method, and the clamping method of the electrode is mechanical;

(2) Under the protection of argon or helium or a mixture of argon and helium, use electric spark equipment for deposition treatment;

(3) During the deposition process, the output power is 400-1300W, the output voltage is 60V-80V, the discharge frequency is 100-700Hz; the flow rate of the protective gas is 18-30L/min, and the specific deposition time is 3-15 minutes.

Before repairing, descaling treatment is carried out on the strengthened repair area to make it bright, and then the repair is carried out. The repair materials used also need to be descaled to make it bright.

The electrode material is conductive, metal or alloy with high specific gravity, including metal W, Mo, Ta; or powder metallurgy material W-Cu, Re-Cu, Ta-Cu; or YG series hard alloy; or W -Cu alloy.

The red copper liner used in the weapon industry has poor performance due to its light weight, but the manufacturing process such as processing technology is relatively easy to realize, while high-quality W-Cu, Re-Cu, Ta-Cu and other multi-phase alloys and single-phase alloys The phase Ni, Mo, W, Ti metal manufacturing process is relatively difficult to realize, but the status quo of copper drug-type cover is still widely used. Using electric spark deposition technology, W alloy or W-Cu alloy is deposited on the drug-type cover copper to increase its quality. improve its performance.

The equipment for deposition treatment in the present invention is EDM deposition treatment equipment or similar equipment with the same characteristics. The parameters of EDM deposition process mainly include: power, voltage, frequency, flow rate of protective gas, deposition time, etc. Only by selecting reasonable process parameters for deposition can we obtain deposits that meet the requirements of use and have excellent performance. In order to provide the basis for selecting process parameters for practical engineering applications, the process test research of tungsten/tungsten copper and YG8 on the surface of red copper was carried out. And analyze the organizational structure of the deposition layer deposited by EDM.

When depositing W electrodes on the Cu surface, the influence of deposition parameters such as output power, output voltage, discharge frequency, protective gas flow rate, and specific deposition time on the thickness and quality of the deposited layer was analyzed, and the surface morphology and structure of the deposited layer were analyzed situation. The following results are obtained:

1. The output power and voltage determine the discharge energy of the electric spark, which has a great influence on the thickness of the deposited layer. The thickness of deposited layer first increases and then decreases with the increase of discharge energy. The discharge energy is very large, causing the deposition layer to peel off, and the temperature of the substrate also rises greatly. For the Cu substrate, the discharge energy should not be too large. Generally, the power is 400-1300W, and the voltage is 60V-80V.

2. The discharge frequency mainly affects the quality and deposition efficiency of the deposited layer. When the discharge frequency is very low, the discharge speed is too slow, the efficiency is low, and the surface roughness is also large. When the frequency is high, the spark discharge speed is fast and continuous, and the efficiency is also high. However, if the working frequency is too high, the electrode is easily burned red, which affects the quality of the deposited layer. Generally, if the quality is not affected, high frequency is better, specifically 100-700Hz.

3. During EDM, the protective gas is very important. Generally, argon or helium or a mixture of argon and helium is used as the protective gas, and the gas flow rate is about 18-30L/min.

4. The quality of the deposited layer will not increase with the increase of deposition time. Blindly pursue the deposition rate, you can not get a larger quality sediment; under certain conditions, there is an optimal specific deposition time, at this time the sediment reaches the maximum quality. Sometimes long-term deposition will cause defects such as cracks in the existing deposition layer, which will have a negative impact on the deposition quality. Therefore, the quality of the deposited layer can be guaranteed only by selecting the specific deposition time reasonably, specifically 3-15 minutes).

5. The surface of the sediment layer is composed of countless sunflower deposition points overlapping each other. The formation of the deposition layer on the surface of the electric spark has undergone a cycle of formation, remelting; re-formation, and re-melting. The final deposition layer is composed of countless These deposition points fuse with each other to form a continuous deposition layer. During the whole process, there is a complete metallurgical bond formed between the electrode material and the matrix in the melting pit, and there is also an incomplete metallurgical bond in which the electrode material and the matrix material are remelted and solidified in the splash zone.

6. The surface of EDM deposition is uneven and orange peel-like. There are some sputtering deposition points and discharge pits, the edge of the melting pit is radial, and the surface of the deposition layer is rough and uneven. There are sedimentary layer and transitional layer, the sedimentary layer is relatively thin, and the transitional layer is not obvious. Moreover, due to the effect of sputtering, the distribution of alloy elements in the deposited layer is uneven.

When Cu-W electrodes are deposited on the Cu surface, the deposition parameters also have an impact on the thickness and quality of the deposited layers, and the effect is roughly the same as that when deposited with W electrodes. There are some similarities in the surface morphology and organizational conditions of the sedimentary layers, but there are some differences.

First of all, the influence of output power and output voltage on the thickness of the deposited layer increases first and then decreases with the increase of discharge energy. The discharge frequency that affects the quality and deposition efficiency of the deposited layer is also the same as when using the W electrode. The optimum values of deposition parameters are: power: 1300W; voltage: 80V; frequency: 300Hz; flow rate of shielding gas: 18L/min.

When Cu-W electrodes are deposited on the Cu surface, the change law of the deposition layer quality with the deposition time is similar to that of the W electrode, and the quality of the deposition layer increases with the increase of the deposition time at the beginning. After reaching a certain deposition time, the quality of the deposited layers began to decrease again. In the beginning, the effect is very obvious. However, the optimal specific deposition time to achieve the maximum deposition quality is different. When using W electrode deposition, it reaches the maximum after 15 minutes of deposition, and the maximum alloying rate is 0.0356mg/mm ² . Before 15 minutes, the quality has been increasing; while using For the Cu-W electrode, the mass reaches the maximum after 12 minutes of deposition, and the maximum alloying rate is 0.0226mg/mm ² .

The deposition layer formation process is the same during EDM. The surface morphology of the deposited layer is the same as when deposited with W electrode. Because the deposition parameters and methods are the same. Due to the impact of splashing, the surface is orange peel. They are composed of countless deposition points remelted and overlapped with each other. There are sedimentary layer and transition layer, but the sedimentary layer is relatively thin.

However, due to the different electrodes, the metal elements transitioning to the matrix melting pit are also different, and the properties of the electrode materials are also different, and the formed cross-section and microstructure are different. When the W electrode is deposited, the W content of the deposited layer is large and the deposited layer is thick, while when the Cu-W electrode is deposited, the deposited layer is relatively thin, and the transition layer is less obvious. This also strongly illustrates that different electrode materials form different deposition layers during the deposition process.

The beneficial effects of the present invention are:

1. The present invention uses a high-energy micro-arc spark deposition equipment (electric spark equipment) by adopting the drug-type cover material (copper) as the deposition object, and uses argon (or helium or argon, helium mixture) under atmospheric conditions. gas) for protection, and deposit W alloy or W-Cu alloy or WC (YG series hard alloy) on the drug-mask material (copper) to improve the surface quality of the drug-mask material, thereby improving the use of the drug-mask performance.

2. In the present invention, a layer of metal material tungsten or Cu-W or WC with high density and high melting point is coated on the inner surface of the copper liner to increase the jet density and achieve the purpose of increasing the penetration depth.

3. In view of the characteristics of Cu and W, the immiscibility of Cu-W liquid phase is difficult to realize by ordinary methods. The invention adopts electric spark deposition technology, utilizes high energy density to make Cu and W form pseudo-alloying, and forms a layer of Cu-W coating on the surface layer of the liner to increase the specific gravity of the jet flow of the Cu liner.

4. The present invention does not need complex equipment such as vapor deposition and vacuum sintering.

5. The present invention does not cause thermal damage to copper, and can be deposited repeatedly. Unlike vapor deposition, which has a limitation on the number of depositions, and unlike vacuum sintering, which is more complicated, this process can be completed only by hand-held operation. Narrow zone or no heat-affected zone; and this method does not require preheating before deposition and annealing after deposition.

6. The present invention is not only applicable to pure copper materials, but also applicable to copper alloys.

Description of drawings

FIG. 1 is the cross-sectional structure of W deposited by spark discharge on the surface of Cu in Example 1. FIG.

Fig. 2 is a composition diagram of the white substance shown in Fig. 1 .

FIG. 3 is the cross-sectional structure of Cu-W deposited on Cu surface by spark discharge in Example 2. FIG.

FIG. 4 is the microstructure of Cu-W deposited by EDM on Cu surface in Example 2. FIG.

FIG. 5 is the surface morphology of WC (YG8) deposited on Cu surface by spark discharge in Example 3. FIG.

FIG. 6 is the cross-sectional structure of WC deposited by EDM on Cu surface in Example 3. FIG.

FIG. 7 is the microstructure of WC deposited by EDM on Cu surface in Example 4. FIG.

FIG. 8 is a composition map of the deposition point when deposited with YG8 electrode material in FIG. 7 .

Fig. 9 is the relationship curve between the thickness of the deposited layer and the operating frequency in Example 5.

FIG. 10 is a graph showing the relationship between the thickness of the deposited layer and the working power in Example 6.

Detailed ways

Example 1

The base material used in the experiment is the red copper material (the mass percentage of copper reaches 99.9%) made of the armor-piercing drug type cover, the size is 16mm × 16mm × 3mm, and the electrode uses a tungsten electrode rod (model: WCe20, dopant CeO ₂ , the content is 1.8%-2.2%, the rest is W), and the diameter is φ3mm.

The experimental equipment used the metal surface strengthening and repairing machine (3H-ES-X800, 3H-ES-1500, 3H-ES-3000) produced by the Institute of Metal Research, Chinese Academy of Sciences (for details, see the Chinese utility model patent, the patent number is 03214166.1). During the deposition process, the argon gas protection is introduced, the electrode material adopts self-rotation mode (axial rotation), the electrode rotation speed is 3000r/min, and the clamping mode of the electrode is mechanical mode. The parameters of EDM deposition are: output power: 420W; discharge frequency: 200Hz; output voltage: 60V; specific deposition time: 6min; protective gas flow rate: 18L/min. During the experiment, the copper substrate and electrode material were first polished with 800# water sandpaper to remove impurities such as copper rust and oxides on the surface, and then the copper substrate was placed in acetone and cleaned with an ultrasonic cleaner.

Figure 1 is the cross-sectional structure (800×) of EDM deposited W on the surface of Cu. The electronic probe was used to analyze the composition of the blocky white substance in the figure. The results are shown in Figure 2, which was produced by Philips. X-ray energy spectrometer XL-FEG analysis results, in the figure: Oka represents the spectral line of oxygen element at Ka; FeKa represents the spectral line of Fe element at Ka; WMa represents the spectrum of W element at Ma WLa, WLb, and WLg all represent tungsten elements, and the following La, Lb, and Lg are calibrated by different spectral lines; EDAXZAF quantification (Standardless) in Chinese is the result calculated by the energy spectrum ZAF correction (standard) (standard value ); Element Normalized Chinese is element planning, the nominal content of elements OK, FK, WL (element), K-ratio (K-ratio); Z, A, F represent atomic coefficient, absorption coefficient, fluorescence, the results of Figure 2 It shows that the electrode material transitions into the deposited layer during the deposition process.

Example 2

The difference from Example 1 is:

The electrode uses a Cu-W electrode (Cu-W75, mass percentage: Cu 25%, impurity 0.3%, and the rest is W) manufactured by powder metallurgy, with a diameter of φ3.6mm.

The experimental equipment still uses the metal surface strengthening and repairing machine (model 3H-ES-X800, 3H-ES-1500, 3H-ES-3000) produced by the Institute of Metal Research, Chinese Academy of Sciences. Argon protection is introduced during the deposition process, and the electrode material is made of Self-rotation mode (axial rotation), the electrode rotation speed is 3000r/min, and the electrode clamping method is mechanical. The parameters of EDM deposition are: output power: 420W; discharge frequency: 100Hz; output voltage: 60V; specific deposition time: 5min; protective gas flow rate: 30L/min. During the experiment, the copper substrate and electrode material were first polished with 800# water sandpaper to remove impurities such as copper rust and oxides on the surface, and then the copper substrate was placed in acetone and cleaned with an ultrasonic cleaner.

As shown in Figure 3, the cross-sectional structure of Cu-W deposited by EDM on the Cu surface (800×). It can be seen from the figure that the deposition layer is a layer of black and white material, the deposition points are not continuous, and the deposition layer is also very thin. This layer is a deposition layer formed by the metallurgical reaction between the electrode and the substrate. Since the electrode is a Cu-W material sintered by powder metallurgy, the hardness is very high, and the W content is not very large. The transitional W element in the deposition layer is very limited. . The hardness test was carried out with the HX-I Vickers microhardness tester produced by Wuzhong Micro Test Instrument Factory, and it was also found that the hardness value of the deposited layer is not much different from that of the base material, both about 90HV.

The deposition point has high corrosion resistance, and the deposition layer is white and bright under the scanning electron microscope. The microstructure (2400×) of EDM deposited Cu-W on Cu surface is shown in Fig. 4.

It can be seen from Figure 4 that in the entire sedimentary layer, there are some white spots, some black and white tissue components, and some tiny white spots. The white spots are partly due to the splashing of liquid electrode materials, the accumulation of electrode materials at the edge of the melting pit, these points have a large content of W, and those tiny white spots, these are the fusion of electrode materials and matrix materials in the melting pit Alloyed part. Most of the entire deposition layer is composed of these alloyed structures and large white W electrode materials. Since the electrode material is a Cu-W material sintered by powder metallurgy, during the EDM deposition process, the base material is melted to form a melting pit, the electrode material is also melted and transitions into the melting pit, and the molten electrode material will also decompose. Since Cu and W in the Cu-W material are not chemically combined, the decomposition is relatively easy.

Example 3

The difference from Example 1 is:

The electrode uses cemented carbide YG8, its main component is WC (tungsten carbide is the main component of YG series alloys), and its diameter is φ4mm. The deposition parameters are: output power: 420W; discharge frequency: 100Hz; output voltage: 60V; specific deposition time 5min; protective gas flow rate: 30L/min.

As shown in Figure 5, the surface morphology of EDM deposited WC (YG8) on Cu surface; as shown in Figure 6, the cross-sectional structure of EDM deposited WC on Cu surface (800×). The deposition points are not very continuous, and the deposition layer is relatively thin, but the transition layer is relatively thick. Compared with the deposition with W electrode, the deposition layer is relatively similar, but the white spots are much less, and there are more black substances, and the transition layer between the deposition surface layer and the substrate is more obvious. We already know that the white spots are produced by the enrichment and solidification of W in the molten electrode material. It is composed of individual deposition points. A portion of the matrix material is also fused in the deposited layer. That is to say, the deposited layer is formed by the metallurgical reaction and re-fusion of the electrode and the substrate.

When EDM deposits WC on the surface of Cu, it is also different from when it is deposited with Cu-W electrodes. In the figure, we can see an obvious white and bright layer, and there are some white and black mixed substances on the deposition surface. This black and white mixed substance should be It is formed by the metallurgical reaction between the liquid electrode material and the base material in the molten pit during EDM deposition, and a part of it is fused and solidified after cooling. This tissue is distributed both on the surface and inside of the sediment layer. Moreover, there are also white W patches in the deposited layer. It shows that during the deposition process, the original deposition point and the electrode element-enriched area at the edge of the melting pit were remelted, and there may be more electrode materials in the new melting pit.

Example 4

The difference from Example 1 is:

The electrode uses cemented carbide YG8, the main component is WC, and the diameter is φ4mm. The deposition parameters are: output power: 420W; discharge frequency: 200Hz; output voltage: 60V; specific deposition time: 6min; protective gas flow rate: 18L/min. After the metallographic sample is prepared, ground and polished, it is etched with an aqueous ferric chloride hydrochloric acid solution (by weight percentage, FeCl ₃ : 3%, HCl: 10%), cleaned with absolute alcohol and dried. As shown in Figure 7, the microstructure (4000×) of EDM deposited WC on the Cu surface, the composition of the white deposit in the deposition layer was scanned with a scanning electron microscope, and the composition results of the deposition point are shown in Figure 8.

Embodiment 5 Deposition layer changes influence with working frequency

The parameters of EDM W are: output power 420W, output voltage 60V, argon gas flow rate 30L/min, specific deposition time 3min, and different working frequencies are selected for deposition.

The relationship between the working frequency and the thickness of the deposited layer (increase in thickness means increase in quality) is shown in Fig. 9 . When the frequency is 30Hz, the discharge speed is too slow, and the electric spark is very weak. And because the thermal conductivity of copper is very good, the heat generated by one electric spark discharge is quickly dissipated, and the discharge frequency is very low, and the discharge speed is too slow, so the work is extremely discontinuous and the surface roughness is also large. When the frequency is high, the discharge interval is short, the spark discharge is relatively continuous, and the surface roughness of the deposited layer is relatively low. Below 300Hz, as the frequency increases, the spark discharge effect becomes better and better, and the thickness of the deposited layer increases significantly. At 300Hz, the thickness of the deposited layer reaches the maximum, and the discharge is also very stable and continuous. When the frequency rises to more than 700Hz, the discharge is quite continuous, and the metal melting zone of the deposition layer is relatively large, which is conducive to the infiltration of metal atoms of the electrode material into the base material, and at the same time improves the surface roughness of the deposition layer, and can Improve work efficiency. But when the frequency is too high, the electrode material will also be burned red, which affects the quality of the deposited layer.

Embodiment 6 deposit layer changes influence with working power

During the experiment, six different powers of 210W, 420W, 750W, 960W, 1290W and 1500W were selected for deposition.

EDM parameters The output voltage is 60V, the discharge frequency is 200Hz, the flow rate of argon gas is 30L/min, the specific deposition time is 3min, and different powers are selected for deposition.

When depositing tungsten on copper, the relationship between the thickness of the deposited layer and the change of the working power is shown in Figure 10. When other parameters of EDM deposition are constant, the thickness of the deposited layer increases first and then decreases with the increase of the output power. When the working power is 1290W When it reaches the maximum, the thickness of the specimen is 43.3 μm. When the power is small, within a certain deposition time, as the power increases, the discharge energy increases, and the amount of electrode melting also increases, so the thickness of the deposited layer increases with the increase of power; when the power is too large, the discharge energy is very large, Although the amount of electrode melting increases, due to the increase in the heat input to the substrate, a large thermal stress may be generated in the substrate, causing the deposition layer to peel off. layer.

Claims (1)

1. A copper or copper alloy surface electric spark strengthening method is characterized in that the specific steps are as follows: (1) The corresponding electrode is used for deposition treatment, the electrode adopts the self-rotating method, and the clamping method of the electrode is mechanical; The electrode material is metal W, Mo or Ta; or powder metallurgy material W-Cu, Re-Cu or Ta-Cu; or cemented carbide YG8; or W-Cu alloy; (2) Under the protection of argon or helium or a mixture of argon and helium, use electric spark equipment for deposition treatment; (3) During the deposition process, the output power is 400-1300W, the output voltage is 60V-80V, the discharge frequency is 100-700Hz; the flow rate of the protective gas is 18-30L/min, and the specific deposition time is 3-15 minutes.

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