Glycol solution for electrochemical discharge machining of metal matrix composites

Abstract

The present application belongs to the technical field of metal material processing, and particularly relates to a glycol solution for discharge electrochemical composite machining of metal matrix composite materials. The present application combines electrolytic machining and discharge machining, and simultaneously uses a glycol solution to replace an existing water-based electrolyte for discharge-electrochemical composite machining of silicon carbide particle reinforced metal matrix composite materials. The glycol solution can take the products and Joule heat of the machining process away from the machining area, avoid the continuous generation of a passivation film on the surface of the metal matrix to hinder machining and cause uneven machining surfaces and rough groove sidewall profiles, and thus improve machining efficiency and machining quality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal material processing, and particularly relates to a glycol solution for discharge electrochemical composite machining of metal matrix composite materials. BACKGROUND

[0002] Since the hardness of the reinforcing particles in the silicon carbide particle reinforced metal matrix composite material is high, serious tool wear exists when the material is machined by using the traditional mechanical machining method, leading to low machining efficiency and high machining cost, and serious machining defects exist on the surface of the material.

[0003] Electrochemical machining is a non-contact machining method based on the principle of electrochemical anodic dissolution of a metal workpiece in a working liquid. The machining method is not limited by the hardness of the material in the machining process, and there is no machining stress and tool wear. However, when machining the silicon carbide particle reinforced metal matrix composite material, especially the silicon carbide particle reinforced aluminum matrix composite material, since the reinforcing phase silicon carbide particles in the material do not have conductivity, they will not be removed by electrochemical machining, and in the continuous feeding of the electrode, the workpiece and the tool will be in contact, causing short circuit to occur, and the machining efficiency of the silicon carbide particle reinforced metal matrix composite material is relatively low. The discharge machining is a machining method based on spark discharge between the tool cathode and the workpiece anode to remove the material by electro-erosion. The machining efficiency of the silicon carbide particle reinforced metal matrix composite material is relatively high, and the machining flexibility is strong, but the machining process will produce a recast layer and a heat affected layer on the surface of the workpiece, reducing the machining quality of the surface of the workpiece.

[0004] The discharge-electrochemical composite machining is a new non-contact machining method for difficult-to-machine materials, which combines the advantages of electrochemical machining and discharge machining. In the machining process, the discharge machining removes a large amount of material, and the subsequent electrochemical machining removes the recast layer and other defects left on the surface after the discharge machining, greatly improving the machining efficiency and the surface quality of the machined workpiece. The mainstream electrolyte for discharge-electrochemical composite machining is water-based sodium chloride or sodium nitrate electrolyte. However, when machining the silicon carbide particle reinforced metal matrix composite material, although the water-based electrolyte has high machining efficiency, a passivation film will be generated in the area where the metal matrix exists at a low current density, hindering the machining process and reducing the surface quality after machining. At the same time, serious stray corrosion will occur in the area where the metal matrix exists at a high current density, resulting in rough surface after machining, rough profile of the groove sidewall, and serious reduction of the machining quality. SUMMARY

[0005] Therefore, the present application aims to provide a method for electrochemical discharge machining of silicon carbide particle reinforced metal matrix composite in ethylene glycol solution, which can effectively improve the machining quality and efficiency of the silicon carbide particle reinforced metal matrix composite.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions.

[0007] The present application provides a method for electrochemical discharge machining of silicon carbide particle reinforced metal matrix composite in ethylene glycol solution, which comprises the following steps:

[0008] The silicon carbide particle reinforced metal matrix composite is subjected to electrochemical discharge machining by using ethylene glycol solution.

[0009] The solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution at 20℃ is 0.1-1 mol / L.

[0010] Preferably, the mass percentage of the silicon carbide particles in the silicon carbide particle reinforced metal matrix composite is 40-70%.

[0011] Preferably, the voltage of the electrochemical discharge machining is 30-40V.

[0012] Preferably, the pulse frequency of the electrochemical discharge machining is 40-50 kHz.

[0013] Preferably, the machining speed of the electrochemical discharge machining is 10-20 μm / s.

[0014] Preferably, the duty cycle of the electrochemical discharge machining is 25%.

[0015] Preferably, the flow speed of the ethylene glycol solution is 0.1-1 m / s.

[0016] Preferably, the electrochemical discharge machining is as follows: the positive electrode of the pulse power source is connected to the silicon carbide particle reinforced metal matrix composite, the negative electrode is connected to a rod-shaped electrode, the initial machining gap is set, the pulse power source is turned on, and the rod-shaped electrode is fed to machine the silicon carbide particle reinforced metal matrix composite.

[0017] Preferably, the material of the rod-shaped electrode is tungsten-copper alloy, tungsten steel alloy or stainless steel, the diameter is 2-10 mm, the length is 40-60 mm, and the cross section is circular.

[0018] The present application also provides an ethylene glycol solution for electrochemical discharge machining of metal matrix composite, wherein the solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution at 20℃ is 0.1-1 mol / L.

[0019] The present application provides a discharge-electrochemical machining method of silicon carbide particle reinforced metal matrix composite in ethylene glycol-based solution, comprising the following steps: using ethylene glycol solution to discharge-electrochemically composite machine silicon carbide particle reinforced metal matrix composite; the solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution is 0.1-1 mol / L at 20℃. The present application combines electrolytic machining and discharge machining, and uses ethylene glycol solution to replace the existing water-based electrolyte to discharge-electrochemically composite machine silicon carbide particle reinforced metal matrix composite. The ethylene glycol solution can take the product and Joule heat away from the machining area. Compared with the water-based electrolyte, the viscosity of the ethylene glycol solution is larger, the moving speed of anions and cations in the electrolyte is slower, the localization of machining is better, and local efficient and uniform corrosion can be realized. Moreover, most of the machining products in the ethylene glycol solution are soluble substances, which can effectively reduce the accumulation of insoluble products on the machined surface, avoid the continuous generation of passivation film on the metal matrix surface to hinder machining and the quality problem of rough machining surface and rough groove sidewall profile, thereby improving the machining efficiency and machining quality. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of discharge-electrochemical composite machining of silicon carbide particle reinforced metal matrix composite in the present application, wherein 1-electrolyte, 2-rod electrode, 3-pulse power supply, 4-silicon carbide particle reinforced metal matrix composite workpiece;

[0021] Figure 2 It is a scanning electron microscope image of the groove structure machined by Example 1 of the present application;

[0022] Figure 3 It is a scanning electron microscope image of the groove structure machined by Example 2 of the present application;

[0023] Figure 4 It is a scanning electron microscope image of the groove structure machined by Comparative Example 1 of the present application;

[0024] Figure 5 It is a scanning electron microscope image of the groove structure machined by Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0025] The present application provides a discharge-electrochemical machining method of silicon carbide particle reinforced metal matrix composite in ethylene glycol-based solution, comprising the following steps:

[0026] Using ethylene glycol solution to discharge-electrochemically composite machine silicon carbide particle reinforced metal matrix composite;

[0027] The solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution at 20℃ is 0.1-1 mol / L.

[0028] Unless otherwise specified, the source of the raw materials used in the present application is not particularly limited, and commercially available products known to those skilled in the art can be used.

[0029] The present application utilizes the ethylene glycol solution to perform discharge-electrochemical combined machining on the silicon carbide particle reinforced metal matrix composite material.

[0030] In the present application, the solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution at 20℃ is 0.1-1 mol / L, preferably 0.5-1 mol / L. By setting the concentration of the ethylene glycol solution in the above range, the electrochemical effect can be avoided due to too low concentration, which reduces the surface quality after machining, and the machining precision can be avoided due to too high concentration, which increases the stray corrosion in the machining area.

[0031] In the present application, the mass percentage of silicon carbide particles in the silicon carbide particle reinforced metal matrix composite material is preferably 40-70%, more preferably 45-65%; the metal matrix of the silicon carbide particle reinforced metal matrix composite material is preferably aluminum-based.

[0032] In the present application, the discharge-electrochemical combined machining is as follows: the positive electrode of the pulse power is connected to the silicon carbide particle reinforced metal matrix composite material, the negative electrode is connected to a rod-shaped electrode, the initial machining gap is set, the pulse power is turned on, and the rod-shaped electrode is fed to machine the silicon carbide particle reinforced metal matrix composite material.

[0033] In the present application, the material of the rod-shaped electrode is preferably tungsten-copper alloy, tungsten steel alloy or stainless steel, more preferably tungsten-copper alloy, the diameter is preferably 2-10 mm, more preferably 2-5 mm, the length is preferably 40-60 mm, more preferably 50 mm, and the cross section is preferably circular.

[0034] The present application does not have special limitations on the machining, and the machining methods known in the art can be used. In the embodiments of the present application, the machining body is a slot machining.

[0035] During the machining process, the discharge machining removes a large amount of the silicon carbide particle reinforced metal matrix composite material, and then the electrolytic machining can remove the recast layer defects left on the material surface after the discharge machining, greatly improving the machining efficiency and the surface quality of the machined workpiece.

[0036] In the present application, the voltage of the discharge-electrochemical combined machining is preferably 30-40V, and more preferably 35-40V. By setting the voltage of the discharge-electrochemical combined machining in the above range, the present application can avoid the decrease of the discharge effect due to the too low voltage, the decrease of the volume of the removed material per unit time, and the difficulty in improving the machining efficiency.

[0037] In the present application, the pulse frequency of the discharge-electrochemical combined machining is preferably 40-50kHz, and more preferably 40-45kHz. By setting the pulse frequency of the discharge-electrochemical combined machining in the above range, the present application can avoid the increase of the discharge energy due to the too low pulse frequency, the increase of the electrode wear, and the decrease of the dimensional accuracy, and avoid the decrease of the surface quality after machining due to the too high pulse frequency which promotes the electrolysis.

[0038] In the present application, the machining speed of the discharge-electrochemical combined machining is preferably 10-20μm / s, and more preferably 15-20μm / s; the duty cycle of the discharge-electrochemical combined machining is preferably 25%; and the flow speed of the ethylene glycol solution is preferably 0.1-1m / s, and more preferably 0.4-0.6m / s.

[0039] Figure 1 A schematic diagram of the discharge-electrochemical combined machining of the silicon carbide particle reinforced metal matrix composite in the present application is shown in FIG. 1, wherein 1 is an electrolyte, 2 is a rod-shaped electrode, 3 is a pulse power source, and 4 is a silicon carbide particle reinforced metal matrix composite workpiece. As shown in FIG. 1, the present application connects the positive pole of the pulse power source 3 to the silicon carbide particle reinforced metal matrix composite workpiece 4, and connects the negative pole of the pulse power source 3 to the rod-shaped electrode 2. The relative positions of the rod-shaped electrode 2 and the silicon carbide particle reinforced metal matrix composite workpiece 4 are adjusted, the initial machining gap is set, the pulse power source is turned on, and the rod-shaped electrode 2 is fed to perform slot machining on the silicon carbide particle reinforced metal matrix composite workpiece 4. Figure 1 Compared with the water-based electrolyte, the ethylene glycol solution has a larger viscosity and slower movement speed of the anions and cations in the electrolyte, and has a better machining localization, so that the local efficient and uniform corrosion can be realized. Moreover, most of the machining products in the ethylene glycol solution are soluble substances, which can effectively reduce the accumulation of insoluble products on the machined surface, avoid the continuous generation of passivation film on the metal matrix surface to hinder the machining and cause the quality problems of the uneven machining surface and the rugged slot side wall, and thus improve the machining efficiency and machining quality.

[0040] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application, but they should not be understood as limitations to the protection scope of the present application.

[0041] Example 1

[0042]

[0043] ​1 mol / L ethylene glycol solution was prepared by adding 1 mol of sodium chloride (analytical pure) into ethylene glycol (standard reagent for industrial use) to make 1 L solution at room temperature;

[0044] The positive pole of the pulse power was connected to the workpiece of silicon carbide particle reinforced aluminum matrix composite (consisting of an aluminum alloy matrix and silicon carbide particles loaded on the aluminum alloy matrix, the mass percentage of silicon carbide particles being 63%), the negative pole was connected to a rod-shaped electrode (tungsten-copper alloy material, diameter 2 mm, length 50 mm, cross section circular), 40 V voltage, 25% duty cycle, 40 kHz pulse frequency, machining speed 10 μm / s, flow speed of ethylene glycol solution 0.4 m / s, and the silicon carbide particle reinforced aluminum matrix composite was subjected to discharge-electrochemical combined machining in 1 mol / L ethylene glycol solution, and the rod-shaped electrode was fed for slotting machining.

[0045] Example 2

[0046] 1 mol / L ethylene glycol solution was prepared by adding 1 mol of sodium chloride (analytical pure) into ethylene glycol (standard reagent for industrial use) to make 1 L solution at room temperature;

[0047] The positive pole of the pulse power was connected to the workpiece of silicon carbide particle reinforced aluminum matrix composite (consisting of an aluminum alloy matrix and silicon carbide particles loaded on the aluminum alloy matrix, the mass percentage of silicon carbide particles being 63%), the negative pole was connected to a rod-shaped electrode (tungsten-copper alloy material, diameter 2 mm, length 50 mm, cross section circular), 40 V voltage, 25% duty cycle, 40 kHz pulse frequency, machining speed 20 μm / s, flow speed of ethylene glycol solution 0.4 m / s, and the silicon carbide particle reinforced aluminum matrix composite was subjected to discharge-electrochemical combined machining in 1 mol / L ethylene glycol solution, and the rod-shaped electrode was fed for slotting machining.

[0048] Comparative Example 1

[0049] 1 mol / L ethylene glycol solution was prepared by adding 1 mol of sodium chloride (analytical pure) into ethylene glycol (standard reagent for industrial use) to make 1 L solution at room temperature;

[0050] The positive electrode of the pulse power supply is connected to the silicon carbide particle-reinforced aluminum matrix composite workpiece (composed of an aluminum alloy matrix and silicon carbide particles loaded on the aluminum alloy matrix, with a silicon carbide particle mass percentage of 63%), and the negative electrode is connected to a rod-shaped electrode (made of tungsten copper alloy, with a diameter of 2 mm, a length of 50 mm, and a circular cross-section). A voltage of 40 V, a duty cycle of 25%, a pulse frequency of 30 kHz, a processing speed of 10 μm / s, and a flow rate of ethylene glycol solution of 0.4 m / s are used to perform discharge-electrochemical composite machining on the silicon carbide particle-reinforced aluminum matrix composite in a 1 mol / L ethylene glycol solution. The rod-shaped electrode is used for grooving.

[0051] Comparative Example 2

[0052] At room temperature, 47g of sodium chloride was added to deionized water to prepare a 1L solution. The sodium chloride 6 was analytical grade and the deionized water 7 was an industrial standard reagent to obtain a water-based electrolyte.

[0053] The positive electrode of the pulse power supply is connected to the silicon carbide particle-reinforced aluminum matrix composite workpiece (composed of an aluminum alloy matrix and silicon carbide particles loaded on the aluminum alloy matrix, with a silicon carbide particle mass percentage of 63%), and the negative electrode is connected to a rod-shaped electrode (made of tungsten copper alloy, with a diameter of 2 mm, a length of 50 mm, and a circular cross-section). A voltage of 40 V, a duty cycle of 25%, a pulse frequency of 40 kHz, a processing speed of 20 μm / s, and a flow velocity of 0.1 m / s for the water-based electrolyte are used to perform discharge-electrochemical composite processing on the silicon carbide particle-reinforced aluminum matrix composite in the water-based electrolyte. The rod-shaped electrode is used for grooving.

[0054] Performance testing

[0055] Electron microscopy scanning tests were performed on the grooved structures of Examples 1-2 and Comparative Examples 1-2, and the results are as follows: Figures 2 to 5 As shown.

[0056] like Figure 2 As shown, the sidewall profile of the groove structure obtained by processing in Example 2 is improved, the localization of processing is improved, and there is basically no stray corrosion around it.

[0057] like Figure 3 As shown, the sidewall profile of the tank structure obtained by processing in Example 3 is improved, the processing localization is good, and there is basically no stray corrosion around it. While achieving the same processing efficiency as in water-based electrolytes, the processing quality is improved.

[0058] like Figure 4 As shown, the initial processing of Comparative Example 1 yielded a groove structure with a certain sidewall profile. A small amount of stray corrosion was present around it. However, due to the low pulse frequency and low discharge energy, the material removal efficiency was low, resulting in low processing quality.

[0059] As Figure 5 The groove structure bottom surface processing quality of the processing of Comparative Example 2 is poor, the processing localization is poor, the edge profile is not obvious, and there is obvious stray corrosion around the groove edge.

[0060] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application but not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, which all belong to the protection scope of the present application.

Claims

1. A method of electrochemical discharge machining of a silicon carbide particle reinforced metal matrix composite in a glycol-based solution, characterized in that, The method comprises the following steps: The silicon carbide particle reinforced metal matrix composite is processed by discharge-electrochemical composite machining with an ethylene glycol solution; The solvent of the ethylene glycol solution is ethylene glycol, and the solute is sodium chloride; the concentration of the ethylene glycol solution is 0.1-1 mol / L at 20℃; The mass percentage of the silicon carbide particles in the silicon carbide particle reinforced metal matrix composite is 40-70%; the silicon carbide particle reinforced metal matrix composite is a silicon carbide particle reinforced aluminum matrix composite; The pulse frequency of the discharge-electrochemical composite machining is 40-50 kHz; The processing speed of the discharge-electrochemical composite machining is 10-20 μm / s; The discharge-electrochemical composite machining is as follows: the positive pole of a pulse power source is connected to the silicon carbide particle reinforced metal matrix composite, the negative pole is connected to a rod-shaped electrode, an initial processing gap is set, the pulse power source is turned on, and the rod-shaped electrode is fed to process the silicon carbide particle reinforced metal matrix composite; The rod-shaped electrode is made of tungsten-copper alloy, tungsten steel alloy or stainless steel, has a diameter of 2-10 mm, a length of 40-60 mm, and a circular cross section.

2. The electro-discharge- electrochemical machining method according to claim 1, characterized by The voltage of the discharge-electrochemical composite machining is 30-40 V.

3. The method according to claim 1, wherein The duty cycle of the discharge-electrochemical composite machining is 25%.

4. The method of electrochemical discharge machining according to claim 1, wherein The flow speed of the ethylene glycol solution is 0.1-1 m / s.

Images