An electrolyte solution

Abstract

An electrolyte solution for electrochemical processing is provided. The electrolyte solution comprises a substantially anhydrous ionic solvent, an ionizable material in the form of an inorganic salt, and a viscosity modifier. The electrolyte has a viscosity in the range of 1 mPa·s to 50 mPa·s at 20 °C.

Description

Technical Field

[0001] This invention relates to an electrolyte solution and an electrochemical processing technology. Background Technology

[0002] Electrochemical machining (e.g., electrochemical jetting) is a process for selectively machining the surface of a workpiece. This is accomplished by applying a voltage between a component of the electrochemical machining apparatus (e.g., a nozzle) and the surface to be machined, while simultaneously distributing an electrolyte flow or jet from the nozzle onto the surface. This machining method enables the machining of surfaces through electrochemical reactions, allowing surfaces to be machined as long as the surface material is conductive. This process allows surfaces to be roughened, for example, to improve the bonding / attachment of parts or surface coatings. The machining can also improve the optical and / or tribological properties of the surface and polish material surfaces.

[0003] To achieve ion transfer, a processing medium (i.e., an electrolyte solution) is required in electrochemical processing techniques. This ion transfer enables materials to be added to or removed from the target surface.

[0004] These processing media are traditionally aqueous electrolytes. However, when used in some electrochemical machining processes, these can pose problems because they can cause passivation surfaces to form on some metals and alloys (such as titanium and steel) during the electrochemical machining process. This can result in lower machining accuracy and a reduced ability to create repeatable patterns on these surfaces.

[0005] Existing non-aqueous electrolyte solutions typically have high viscosity and are used in bath electrochemical machining systems. These electrolyte solutions are unsuitable for spraying directly onto the workpiece surface due to their high viscosity. These conventional non-aqueous electrolyte solutions have been limited to applications such as metal deposition and metal polishing because their conductivity is generally poor (deposition and polishing require lower current density levels compared to electrochemical machining processes).

[0006] The present invention seeks to overcome or at least mitigate one or more problems associated with the prior art. Summary of the Invention

[0007] According to a first aspect, an electrolyte solution for an electrochemical processing technology is provided, the electrolyte solution comprising: a substantially anhydrous ionic solvent, an ionizable material in the form of an inorganic salt, and a viscosity modifier, wherein the electrolyte comprises a viscosity in the range of 1 to 50 mPa·s at 20 °C.

[0008] Viscosity modifiers may contain water-based inorganic salt solutions.

[0009] Viscosity modifiers can be concentrated water-based inorganic salt solutions.

[0010] Viscosity modifiers can be saturated water-based inorganic salt solutions.

[0011] The concentration of a saturated solution can be at or near the saturation point of a water-based inorganic salt solution. The concentration of a water-based salt solution can be approximately at the saturation point.

[0012] The concentration of water-based inorganic salt solutions can be in the range of 80%-100% of the concentrated solution. The concentration of water-based inorganic salt solutions can be in the range of 90%-10% of the concentrated solution. The concentration of water-based inorganic salt solutions can be in the range of 95%-100% of the concentrated solution.

[0013] Inorganic salt aqueous solutions can have molar concentrations ranging from 0.1 M to 5 M. Inorganic salt aqueous solutions can have molar concentrations ranging from 1 M to 5 M.

[0014] The concentration of the viscosity modifier in the electrolyte solution can be less than 50 wt.%, and optionally the concentration of the viscosity modifier in the electrolyte solution is in the range of 20 wt.% to 40 wt.%, for example, about 30 wt.%.

[0015] The concentration of the essentially anhydrous ionic solvent can be at least 50 wt.%, optionally at least 60 wt.%, for example, about 70 wt.%.

[0016] Ionizable materials may include compounds of the formula MX, wherein M may be selected from Na. + K + Ca 2+ Mg 2+ Cu 2+ and Zn 2+ Or a combination thereof, X can be selected from F - Cl - ,Br - I - NO 3- and SO4 2- Or a combination thereof.

[0017] Solvents that are essentially anhydrous may contain polyols.

[0018] The solvents that are essentially anhydrous can be selected from ethylene glycol, glycerol, methanol, ethanol, 1-propanol, 2-propanol and / or propylene glycol.

[0019] The solvent, which is essentially anhydrous, can be selected from ethylene glycol and / or glycerol.

[0020] Solvents that are essentially anhydrous may contain quaternary ammonium salts.

[0021] The quaternary ammonium salt may be selected from one or more of choline chloride, tetraethylammonium chloride and / or tetramethylammonium chloride.

[0022] A solvent that is essentially anhydrous can be a deep eutectic solvent containing ethylene glycol and choline chloride.

[0023] Essentially anhydrous ionic solvents may include choline chloride in a ratio of 1:2 to 1:5 with ethylene glycol.

[0024] The ions that are essentially anhydrous may include choline chloride in a ratio of approximately 1:3 to ethylene glycol.

[0025] The pH of the electrolyte solution can be in the range of 5 to 9.

[0026] The electrolyte may include a viscosity in the range of 5 to 30 mPa·s at 20 °C, and optionally, the electrolyte may include a viscosity in the range of 10-15 mPa·s at 20 °C.

[0027] The electrolyte solution may have a conductivity of at least 10 mS / cm.

[0028] The electrolyte solution may have a conductivity in the range of 10 mS / cm to 40 mS / cm, and optionally, the electrolyte solution may have a conductivity in the range of 20 mS / cm to 30 mS / cm.

[0029] According to a second aspect, an electrochemical machining process is provided for machining the surface of a workpiece using an electrochemical machining apparatus, the electrochemical machining apparatus including a nozzle configured for dispensing an electrolyte solution jet toward the surface of the workpiece, the electrochemical machining process including the steps of: dispensing the aforementioned electrolyte solution jet from the nozzle of the electrochemical machining apparatus toward the surface of the workpiece; applying a charge to the nozzle of the electrochemical machining apparatus and applying a charge to the surface of the workpiece, such that the nozzle and the surface define a first electrode and a second electrode of an electrolytic cell.

[0030] This process can apply pressure below 400 A / cm. 2 Optional, below 150A / cm 2 Optionally, it can be lower than 100A / cm 2 For example, in the range of 25 to 100 A / cm 2 The current density within the range. Attached Figure Description

[0031] The embodiments will now be described with reference to the accompanying drawings, in which:

[0032] Figure 1 An electrochemical processing apparatus according to one embodiment is shown, comprising a base unit and a processing unit, wherein the processing unit is operated by a user; and

[0033] Figure 2 yes Figure 1 A schematic diagram of the electrochemical processing device. Detailed Implementation

[0034] This invention relates to electrolyte solutions for electrochemical processing, polishing and / or etching of metals.

[0035] The electrolyte solution is capable of being ejected (e.g., sprayed) from the nozzle toward the surface of the workpiece and has a sufficiently high electrolytic conductivity to carry a "high" current (e.g., exceeding 1 A) through the nozzle. The nozzle can be, for example, a 1 mm circular nozzle. In alternative arrangements, the nozzle can be configured as a substantially rectangular nozzle, for example having a width of at least 5 mm or 10 mm and a depth of about 0.2 mm. It should be understood that the size and geometry of the nozzle can be varied to suit the application.

[0036] It has been found that the electrolyte solution of the present invention produces less passivation of metal surfaces (e.g., titanium, titanium alloys, steel, iron, etc.) during electrochemical processing, which enables the production of significantly smoother processed surfaces compared to water-salt electrolytes.

[0037] One embodiment of the electrolyte solution provides an ionic solvent that is substantially anhydrous, an ionizable material in the form of an organic salt, and a viscosity modifier.

[0038] Electrolyte solutions include viscosities ranging from 1 to 50 mPa·s at 20°C. Electrolyte solutions may also include viscosities ranging from 5 to 40 mPa·s at 20°C, typically from 5 to 30 mPa·s at 20°C, typically from 5 to 20 mPa·s at 20°C, typically from 10 to 15 mPa·s at 20°C, and typically from 15 to 20 mPa·s at 20°C.

[0039] A substantially anhydrous ionic solvent can be considered an anhydrous solvent. A substantially anhydrous solvent may include solvents containing a small amount of water. For example, a substantially anhydrous solvent may include up to 1 wt.% water, typically up to 0.5 wt.% water, such as up to 0.1 wt.% water (i.e., in the range of 0-1 wt.%, typically 0.01-0.5 wt.%, or 0.05-0.1 wt.%).

[0040] Ionic solvents that are essentially anhydrous can be polyols. Polyols particularly suitable for electrochemical processing of electrolyte solutions are ethylene glycol and glycerol, or combinations thereof.

[0041] In one embodiment, the substantially anhydrous solvent includes ethylene glycol. Ethylene glycol has a lower viscosity at room temperature than other potential solvents, thus allowing it to be more easily sprayed toward the surface of the workpiece. The substantially anhydrous solvent may include one or more of glycerol, methanol, ethanol, 1-propanol, 2-propanol, and / or propylene glycol.

[0042] In another embodiment, the substantially anhydrous solvent comprises a combination of ethylene glycol and glycerol. The ratio of ethylene glycol to glycerol can be approximately 50:50 wt.%, typically 70:30 wt.%, typically 90:10 wt.%, or typically 95:5 wt.%.

[0043] Ionic solvents that are essentially anhydrous can further contain quaternary ammonium salts. It has been found that incorporating quaternary ammonium salts into essentially anhydrous solvents can increase the solubility of the salts in those solvents.

[0044] Ionic solvents that are essentially anhydrous may include one or more of choline chloride, tetraethylammonium chloride, and / or tetramethylammonium chloride.

[0045] A substantially anhydrous ionic solvent can contain a combination of ethylene glycol and choline chloride. In other words, a substantially anhydrous ionic solvent can be a deep eutectic solvent.

[0046] A substantially anhydrous ionic solvent may include a polyol to quaternary ammonium salt ratio in the range of 1:2 to 1:5. The ratio of polyol to quaternary ammonium salt is typically in the range of 1:3 to 1:4, usually 1:3 to 1:4. A substantially anhydrous ionic solvent may include a polyol to quaternary ammonium salt ratio of approximately 1:3, but typically this ratio can be 1:2, 1:4, or 1:5, or a ratio between these values.

[0047] A substantially anhydrous ionic solvent may include choline chloride in a ratio of 1:2 to 1:5 with ethylene glycol. The ratio of choline chloride to ethylene glycol is typically in the range of 1:3 to 1:4, usually between 1:3 and 1:4. A substantially anhydrous ionic solvent may include choline chloride in a ratio of approximately 1:3 with ethylene glycol, but this ratio can typically be 1:2, 1:4, or 1:5, or somewhere in between.

[0048]

[0049]

[0050] Table 1: Conductivity of choline chloride:ethylene glycol electrolyte solution without viscosity modifiers or additives

[0051] Table 1 shows the conductivity of various compositions of substantially anhydrous ionic solvents, and it was found that the conductivity of substantially anhydrous ionic solvents is too low for effective surface machining of workpieces in electrochemical jetting processes.

[0052] The electrolyte solution used for electrochemically processed surfaces also includes ionizable materials in the form of inorganic salts. Adding inorganic salts to the electrolyte solution increases its conductivity, thus facilitating ion transfer during the electrochemical processing.

[0053] The electrolyte solution includes a viscosity modifier. The purpose of providing the viscosity modifier is to adjust the viscosity of the electrolyte solution within a specified range to facilitate the spraying of the electrolyte solution (e.g., from a nozzle of an electrochemical machining apparatus) toward the surface of the workpiece. In one embodiment, the electrolyte solution includes a viscosity within a predetermined range of 1 mPa·s and 50 mPa·s at 20°C.

[0054] Viscosity modifiers include water-salt solutions. It has been found that using water-salt solutions as viscosity modifiers not only reduces the viscosity of electrolyte solutions, but also increases the concentration of ionizable materials within the electrolyte solution (and thus increases the conductivity of the solution).

[0055] The ionizable material in the electrolyte solution includes an inorganic salt compound of formula MX. M is selected from Na. + K + Ca 2+ Mg 2+ Cu 2+ and Zn 2+ Or a combination thereof. X is selected from F - Cl - ,Br - I - NO3 - and SO4 2- Or a combination thereof. M will typically be a Group I metal, such as Na. + or K + And X is usually a halogen, such as F. - Cl - ,Br - I - .

[0056] Water-salt solutions in electrolyte solutions are concentrated solutions. The concentration of a saturated solution is at or near the saturation point of a water-based inorganic salt solution. It should be understood that the saturation point of a water-salt solution will depend on the salt used.

[0057] The concentration of water-based inorganic salt solutions can be in the range of 80%-100% of the concentration of concentrated solutions, often in the range of 90%-100% of the concentration of concentrated solutions, and often in the range of 95%-100% of the concentration of concentrated solutions. In other words, the concentration of water-based inorganic salt solutions can be in the range of 80%-100% of the concentration point of water-based inorganic salt solutions, often in the range of 90%-100% of the concentration point of water-based inorganic salt solutions, and often in the range of 95%-100% of the concentration point of water-based inorganic salt solutions.

[0058] Providing the viscosity modifier concentration at or near the saturation point maximizes the salt concentration in the electrolyte solution while minimizing its water content. Furthermore, utilizing a solution concentration at or near the saturation point (e.g., reaching but not exceeding) provides a stable solution, preventing or minimizing salt precipitation from the solution. This keeps the salt solution stable during storage. It also helps prevent the introduction of unwanted particles that could be harmful to the electrolyte solution during spraying.

[0059] In some setups, the molar concentration of the water-salt solution in the electrolyte solution ranges from 0.1 M to 5 M, often from 1 M to 5 M. Often, for example, the molar concentration can range from 1 M to 4 M. The molar concentration can be approximately 3 M (e.g., in the range of 2.5 M–3.5 M or 2.9 M–3.1 M), but often the molar concentration can be 1 M, often 2 M, often 4 M, or often 5 M.

[0060] As discussed above, water-based electrolyte solutions present problems when used in some electrochemical machining processes because they can cause passivation surfaces to form on some metals and alloys (such as titanium and steel) during the electrochemical machining process. Therefore, even when using water-salt viscosity modifiers in the electrolyte solution, the water content of the electrolyte solution should be limited so that it is considered essentially water-free.

[0061] The concentration of viscosity modifier (and water in the electrolyte solution) in the electrolyte solution is typically less than 50 wt.%. In other words, the concentration of the water-salt solution in the electrolyte solution is typically less than 50 wt.%. In some embodiments, the concentration of viscosity modifier in the electrolyte solution may be 0-50 wt.%, often 0.1-50 wt.%, often 1-50 wt.%, often 10-50 wt.%, often 20-50 wt.%.

[0062] It has been found that electrochemical processing using electrolytes containing more than 50 wt.% viscosity modifiers is beginning to encounter problems associated with conventional water-salt electrolyte solutions.

[0063] Typically, the concentration of the viscosity modifier in the electrolyte solution (and the concentration of water in the electrolyte solution) is less than 40 wt.%. In other words, the concentration of the water-salt solution in the electrolyte solution is less than 40 wt.%. In some embodiments, the concentration of the viscosity modifier in the electrolyte solution can be 0-40 wt.%, often 0.1-40 wt.%, often 1-40 wt.%, often 10-40 wt.%, often 20-40 wt.%.

[0064] Typically, the concentration of the viscosity modifier in the electrolyte solution (and the concentration of water in the electrolyte solution) is less than 30 wt.%. In other words, the concentration of the water-salt solution in the electrolyte solution is less than 30 wt.%. In some embodiments, the concentration of the viscosity modifier in the electrolyte solution may be 0-30 wt.%, often 0.1-30 wt.%, often 1-30 wt.%, often 10-30 wt.%, often 20-30 wt.%.

[0065] Typically, the concentration of the viscosity modifier in the electrolyte solution (and the concentration of water in the electrolyte solution) is less than 20 wt.%. In other words, the concentration of the water-salt solution in the electrolyte solution is less than 20 wt.%. In some embodiments, the concentration of the viscosity modifier in the electrolyte solution may be 0-20 wt.%, often 0.1-20 wt.%, often 1-20 wt.%, and often 10-20 wt.%.

[0066] Typically, the concentration of the viscosity modifier in the electrolyte solution (and the concentration of water in the electrolyte solution) is less than 10 wt.%. In other words, the concentration of the water-salt solution in the electrolyte solution is less than 10 wt.%. In some embodiments, the concentration of the viscosity modifier in the electrolyte solution may be 0-10 wt.%, often 0.1-10 wt.%, often 1-10 wt.%, and often 5-10 wt.%.

[0067] It should be understood that, where the electrolyte solution is already defined according to the weight percentage of the viscosity modifier, the remainder of the electrolyte solution is provided by an ionic solvent that is essentially anhydrous and an ionizable material.

[0068] The concentration of essentially anhydrous ionic solvents can be at least 50 wt.%, often at least 60 wt.%, often at least 70 wt.%, often at least 75 wt.%, and often at least 80 wt.%.

[0069] The concentration of a substantially anhydrous ionic solvent can be at least 50 wt.%. In other words, the concentration of a substantially anhydrous ionic solvent can be 50-99 wt.%, often 50-95 wt.%, often 50-90 wt.%, often 50-80 wt.%, often 50-70 wt.%, and often 50-60 wt.%.

[0070] The concentration of a substantially anhydrous ionic solvent can be at least 60 wt.%. In other words, the concentration of a substantially anhydrous ionic solvent can be 60-99 wt.%, often 60-95 wt.%, often 60-90 wt.%, often 60-80 wt.%, often 60-70 wt.%.

[0071] The concentration of a substantially anhydrous ionic solvent can be at least 70 wt.%. In other words, the concentration of a substantially anhydrous ionic solvent can be 70-99 wt.%, often 70-95 wt.%, often 70-90 wt.%, and often 70-80 wt.%.

[0072] The concentration of a substantially anhydrous ionic solvent can be at least 80 wt.%. In other words, the concentration of a substantially anhydrous ionic solvent can be 80-99 wt.%, often 80-95 wt.%, and frequently 80-90 wt.%.

[0073] The concentration of a substantially anhydrous ionic solvent can be at least 90 wt.%. In other words, the concentration of a substantially anhydrous ionic solvent can be 90-99 wt.%, often 90-95 wt.%.

[0074] The conductivity of these electrolyte solutions is related to i) the amount of dissolved inorganic salts and ii) viscosity. Adding ionizable materials from water-based viscosity modifiers to the electrolyte solution increases the room-temperature electrolytic conductivity of the electrolyte solution by i) increasing the dissolved salt content and ii) decreasing the viscosity.

[0075] It should be understood that by increasing the temperature of the electrolyte solution, the viscosity will decrease and the conductivity will increase. Therefore, increasing the temperature will allow less viscosity modifier, and thus less water, to be added to the electrolyte solution to achieve the same conductivity / viscosity.

[0076] To suit electrochemical spraying processes, the electrolyte solution can usefully possess high conductivity. Electrolyte solutions typically include those with a conductivity of at least 10 mS / cm, often ranging from 10 to 80 mS / cm, often from 10 to 70 mS / cm, often from 10 to 60 mS / cm, often from 10 to 50 mS / cm, often from 10 to 40 mS / cm, often from 15 to 35 mS / cm, and often from 20 to 30 mS / cm.

[0077] To maintain the sustainability of electrochemical jet treatment / processing of workpiece surfaces in industrial environments, the electrolyte should preferably not be a highly toxic and / or highly acidic / alkaline solution. This also allows the electrolyte solution to remain a low-environmental-impact solution. The electrolyte can be substantially neutral. In other words, the pH of the electrolyte solution can be in the range of 5 to 9 or 6 to 8.

[0078] Example 1

[0079] Table 1 shows the conductivity of various compositions of substantially anhydrous ionic solvents. To increase the conductivity of substantially anhydrous ionic solvents, an ionizable material is added to the substantially anhydrous ionic solvent, wherein the ratio of choline chloride to ethylene glycol solution is 1:3.

[0080] A viscosity modifier containing a 4M sodium chloride aqueous solution was added to a choline chloride:ethylene glycol solution. The concentration of the viscosity modifier varied from 0 wt.% to 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.%. Table 2 shows the conductivity of the electrolyte solutions with different concentrations of viscosity modifier.

[0081]

[0082]

[0083] Table 2: Conductivity of choline chloride:ethylene glycol electrolyte solutions with different concentrations of viscosity modifiers

[0084] A viscosity modifier containing a 4M sodium chloride aqueous solution was added to a choline chloride:ethylene glycol solution. The concentration of the viscosity modifier was varied from 0 wt.% to 100 wt.% in 10 wt.% increments. Table 3 shows the viscosities of the electrolyte solutions with different concentrations of viscosity modifier at room temperature.

[0085]

[0086] Table 3: Viscosity of choline chloride:ethylene glycol electrolyte solution with different concentrations of viscosity modifiers

[0087] Example 2

[0088] Another embodiment of the electrolyte solution used in electrochemical processing includes the following relative concentrations.

[0089] Ethylene glycol 40 wt.%. Choline chloride 30 wt.%. Viscosity modifier 30 wt.% (including: water 24.3 wt.%; sodium chloride 5.7 wt.%)

[0090] This electrolyte solution has been found to be particularly advantageous when processing titanium surfaces.

[0091] Example 3

[0092] Another embodiment of the electrolyte solution for use in electrochemical processing includes the following relative concentrations.

[0093] Essentially anhydrous ionic solvents include 50-55 wt.% ethylene glycol and 40-45 wt.% choline chloride.

[0094] The electrolyte solution may also include a viscosity modifier in the form of an aqueous salt solution. The aqueous salt solution may range from 0.1 wt.% to 50 wt.%.

[0095] The salt can be sodium nitrate. Sodium nitrate can be present in electrolyte solutions up to 5 wt.% (in the range of 0.1 wt.% to 5 wt.%).

[0096] refer to Figure 1 and Figure 2 An electrochemical machining apparatus 10 is shown for performing an electrochemical machining process on the surface 12 of a workpiece.

[0097] The electrochemical processing apparatus 10 includes a base unit 14 and a handheld processing unit 16. The base unit 14 and the processing unit 16 are connected via an umbilical cord 18, through which the base unit 14 can supply power and electrolyte to the processing unit 16.

[0098] It should be understood that the processing unit 16 is designed for manual operation (e.g., Figure 1 (as shown) or as part of an automated process or operated remotely.

[0099] refer to Figure 2 This shows that the processing unit 16 is positioned on the surface 12 of the workpiece.

[0100] The processing unit 16 includes a housing 22, a nozzle 24 positioned within the housing 22, and the nozzle 24 is configured to dispense an electrolyte jet 26 toward the surface 12 of the workpiece. In this arrangement, the nozzle is defined as 1 mm. 2 The area is fixed, but it should be understood that the nozzle area can be varied to suit the application. As shown in the figure, the housing 22 is configured to define a closed working space when positioned against the surface 12 of the workpiece.

[0101] The electrochemical processing apparatus 10 is configured to apply charge to a nozzle 24 and a surface 12. Thus, the nozzle 24 and surface 12 serve as the first and second electrodes of the electrolytic cell. In an alternative arrangement, the processing unit 16 may include an additional electrode separate from the nozzle, and the electrochemical processing apparatus may be configured to apply charge to the additional electrode and the surface 12.

[0102] The electrochemical machining apparatus 10 is intended for use by an operator to perform an electrochemical machining process for machining the surface of a workpiece. The machining process may include the following steps: i) distributing a jet of electrolyte solution according to the aforementioned solution from the nozzle of the electrochemical machining apparatus toward the surface of the workpiece; and ii) applying a charge to the nozzle of the electrochemical machining apparatus and applying the charge to the surface of the workpiece, such that the nozzle and the surface define a first electrode and a second electrode of an electrolytic cell.

[0103] Electrochemical machining processes can apply pressures below 400 A / cm2 The current density. Electrochemical machining processes can apply current densities below 150 A / cm. 2 The current density. Typically, the current density that can be applied in electrochemical machining processes is 10 A / cm. 2 Up to 400A / cm 2 The range is often 10A / cm. 2 Up to 150A / cm 2 It is often 10A / cm 2 Up to 100A / cm 2 It is often 25A / cm 2 Up to 100A / cm 2 It is usually 25A / cm. 2 Up to 75A / cm 2 It is often 40A / cm 2 Up to 60A / cm 2 It is usually around 50 A / cm 2 .

[0104] Traditionally, reducing current density can lead to a decrease in the surface quality of the machined surface. However, it has been found that in electrochemical machining processes, by using an electrolyte solution as discussed above, applying 50 A / cm... 2 A significantly smooth, polished surface can be obtained at a certain current density.

[0105] Electrochemical processing devices can be configured to apply a potential of less than 500V; often, they can apply a potential in the range of 1V to 500V.

[0106] The removal and deposition of material is achieved by an electrolyte supplied through nozzle 24 and sprayed toward surface 12, which applies a potential between nozzle 24 and surface 12, resulting in anodic dissolution of surface 12 or deposition on surface 12.

[0107] In a first operating mode, a negative charge is applied to the nozzle 24 and a positive charge is applied to the surface 12. In this first operating mode, the device 10 etches at the surface 12 to improve its morphology. In a second operating mode, a positive charge is applied to the nozzle 24 and a negative charge is applied to the surface 12. In this second operating mode, a material (e.g., silica particles or an additive coating that allows surface functionalization) can be deposited onto the surface 12 to improve its surface morphology.

[0108] In use, the nozzle 24 is arranged within the housing 22 to be spaced apart from the surface 12. The distance between the electrode 24 and the workpiece surface 12 (i.e., the inter-electrode gap) affects the machining of the surface 12. The nozzle 24 can be moved within the housing 22 so that the distance between the nozzle 24 and the surface 12 can be adjusted to suit specific machining operations.

[0109] In order to apply charge to the nozzle 24 and the surface 12, the base unit 14 includes a power supply 32 for supplying power to the processing unit 16 via the umbilical cord 18. It should be understood that, in order to supply power to the processing unit 16, the power supply 32 may include one or more batteries, or may be connected to an external power source.

[0110] Although it has been referenced Figure 1 and Figure 2 The electrochemical machining apparatus shown describes the electrochemical jetting of a material surface, but it should be understood that the electrolyte solution discussed above can be used in any suitable electrochemical machining apparatus configured to dispense an electrolyte solution jet onto the surface.

[0111] Although the invention has been described above with reference to one or more embodiments, it should be understood that various changes or modifications may be made without departing from the scope defined in the appended claims.

Claims

1. An electrolyte solution for use in electrochemical processing, the electrolyte solution comprising: A substantially anhydrous ionic solvent selected from ethylene glycol and / or glycerol; Ionizable materials in the form of inorganic salts; as well as Viscosity modifier, The electrolyte includes a viscosity in the range of 5 to 30 mPa·s at 20°C. The viscosity modifier comprises an aqueous inorganic salt solution having a molar concentration in the range of 0.1M to 5M, and the concentration of the viscosity modifier in the electrolyte solution is in the range of 10-50 wt.%. The remaining portion of the electrolyte solution is provided by an ionic solvent that is essentially anhydrous and an ionizable material.

2. The electrolyte solution according to claim 1, wherein the concentration of the viscosity modifier in the electrolyte solution is in the range of 20 wt.% to 40 wt.%.

3. The electrolyte solution according to any of the preceding claims, wherein the concentration of the substantially water-free ionic solvent is at least 50 wt.%.

4. The electrolyte solution of any preceding claim, wherein the ionizable material comprises a compound of the formula MX, wherein M is selected from Na + , K + , Ca 2+ , Mg 2+ , Cu 2+ , and Zn 2+ or combinations thereof, and X is selected from F - , Cl - , Br - , I - , NO 3- , and SO4 2- or combinations thereof.

5. The electrolyte solution according to any of the preceding claims, wherein the solvent, which is substantially free of water, comprises a quaternary ammonium salt.

6. The electrolyte solution according to claim 5, wherein the quaternary ammonium salt is selected from one or more of choline chloride, tetraethylammonium chloride and / or tetramethylammonium chloride.

7. The electrolyte solution according to any of the preceding claims, wherein the solvent, which is substantially free of water, is a deep eutectic solvent comprising ethylene glycol and choline chloride.

8. The electrolyte solution according to claim 7, wherein the substantially anhydrous ionic solvent comprises choline chloride in a ratio of 1:2 to 1:

5.

9. The electrolyte solution according to any of the preceding claims, wherein the pH of the electrolyte solution is in the range of 5 to 9.

10. The electrolyte solution according to any of the preceding claims, wherein the electrolyte comprises a viscosity in the range of 10 to 15 mPa·s at 20°C.

11. The electrolyte solution according to any of the preceding claims, wherein the electrolyte solution has a conductivity of at least 10 mS / cm.

12. The electrolyte solution of claim 11, wherein the electrolyte solution has a conductivity in the range of 10 mS / cm to 40 mS / cm.

13. An electrochemical machining process for machining the surface of a workpiece using an electrochemical machining apparatus, the electrochemical machining apparatus including a nozzle configured to dispense a jet of electrolyte solution toward the surface of the workpiece, the electrochemical machining process comprising the following steps: A jet of electrolyte solution according to any of the preceding claims is dispensed from the nozzle of the electrochemical machining apparatus toward the surface of the workpiece; And to apply charge to the nozzle of the electrochemical processing apparatus and to the surface of the workpiece, such that the nozzle and the surface define the first and second electrodes of the electrolytic cell.

14. The electrochemical processing method according to claim 13, wherein the process applies an A / cm value of less than 400 A. 2 The current density.

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