Description:
BACKGROUND
Field of Invention
[001] Embodiments of the present invention generally relate to surface engineering and advanced material processing, and particularly to a micro-electrochemical spark (µECS) process and system for surface modification of Titanium alloys, specifically Ti64 Alloy.
Description of Related Art
[002] Titanium alloys are widely used in aerospace, biomedical, and automotive industries due to their excellent strength-to-weight ratio, corrosion resistance, and biocompatibility. However, their relatively poor surface properties, including limited hardness, wear resistance, and scratch resistance, often restrict their long-term performance in demanding applications. Conventional surface modification techniques include plasma spraying, thermal spraying, electro-deposition, chemical vapor deposition (CVD), ion plating, and laser cladding. While these methods are commercially practiced, they generally require high-temperature setups, vacuum chambers, or sophisticated equipment. The reliance on such infrastructure not only makes these processes capital-intensive but also restricts their use in resource-constrained environments. Furthermore, methods such as plasma spraying and laser cladding are highly energy-intensive, leading to increased operating costs and reduced environmental sustainability. The complexity of equipment maintenance and operation also limits the accessibility and scalability of these technologies for small and medium-scale applications.
[003] Another significant limitation of conventional approaches is the difficulty in achieving precise micron-level control over coating thickness. Uniformity and repeatability at such precision levels are challenging, which compromises the overall quality and consistency of the modified surfaces.
[004] There is thus a need for an improved and advanced system and method for surface modification of Titanium alloy that can administer the aforementioned limitations in a more efficient manner.
SUMMARY
[005] Embodiments in accordance with the present invention provide a system for surface modification of a titanium alloy. The system comprises a container adapted to hold a urea-modified alkaline electrolyte; a cathodic electrode; an anodic titanium alloy workpiece; and a pulsed power supply adapted to apply a pulsed direct current (DC) voltage in the range of 45-55 volts at a frequency in the range of 9-11 kilohertz (kHz) and a duty factor in the range of 35-45% between the cathodic electrode and the anodic titanium alloy workpiece. The system is adapted to generate micro-electrochemical sparks for forming a coating comprising at least one of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds on a surface of the anodic titanium alloy workpiece.
[006] Embodiments in accordance with the present invention further provide a method for surface modification of a titanium alloy. The method comprises steps of placing a cathodic electrode and an anodic titanium alloy workpiece in a urea-modified alkaline electrolyte within a container; applying a pulsed direct current (DC) potential using a pulsed power supply between the cathodic electrode and the anodic titanium alloy workpiece to generate localized sparks; and forming a coating on the anodic titanium alloy workpiece through electrochemical and spark-induced reactions, wherein the coating comprises at least one of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds on a surface of the anodic titanium alloy workpiece.
[007] Embodiments of the present invention may provide a number of advantages depending on their particular configuration. First, embodiments of the present invention may provide a cost-effective surface modification process that eliminates the need for expensive high-temperature or vacuum-based equipment.
[008] Next, embodiments of the present invention may provide a high-precision coating process that achieves micron-level thickness control in the range of 15-25 micrometers (µm), enabling uniform and consistent surface modification.
[009] Next, embodiments of the present invention may provide a hardness enhancement wherein the coated titanium alloy workpiece exhibits a hardness of at least 850 Vickers hardness (HV), that is more than four times higher than the hardness of the uncoated alloy.
[0010] Next, embodiments of the present invention may provide improved wear resistance, reducing material degradation, and extending the service life of titanium alloy components used in aerospace, biomedical, and automotive applications.
[0011] Next, embodiments of the present invention may provide improved scratch resistance, ensuring better surface durability and reducing susceptibility to surface damage during service.
[0012] Next, embodiments of the present invention may provide an environmentally sustainable coating method that consumes less energy compared to conventional plasma spraying or laser cladding techniques, thereby reducing environmental impact. These and other advantages will be apparent from the present application of the embodiments described herein.
[0013] The preceding is a simplified summary to provide an understanding of some embodiments of the present invention. This summary is neither an extensive nor exhaustive overview of the present invention and its various embodiments. The summary presents selected concepts of the embodiments of the present invention in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the present invention are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and still further features and advantages of embodiments of the present invention will become apparent upon consideration of the following detailed description of embodiments thereof, especially when taken in conjunction with the accompanying drawings, and wherein:
[0015] FIG. 1 illustrates a schematic view of a system for surface modification of a titanium alloy, according to an embodiment of the present invention;
[0016] FIG. 2A illustrates an optical image of a coated surface compared to a base uncoated surface of the titanium alloy, according to an embodiment of the present invention;
[0017] FIG. 2B illustrates a field emission scanning electron microscope (FESEM) top-view image of the coating formed on the titanium alloy, according to an embodiment of the present invention;
[0018] FIG. 2C illustrates a FESEM cross-sectional image of the coating formed on the titanium alloy, according to an embodiment of the present invention;
[0019] FIG. 2D illustrates hardness test results showing optical images of indentations on the base surface and the coated surface of the titanium alloy, according to an embodiment of the present invention;
[0020] FIG. 2E illustrates energy dispersive spectroscopy (EDS) analysis results of the coated titanium alloy surface, according to an embodiment of the present invention;
[0021] FIG. 2F illustrates X-ray diffraction (XRD) analysis results depicting formation of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds in the coating, according to an embodiment of the present invention;
[0022] FIG. 2G illustrates scratch test results, according to an embodiment of the present invention;
[0023] FIG. 2H illustrates wear test results, according to an embodiment of the present invention; and
[0024] FIG. 3 depicts a flowchart of a method for surface modification of a titanium alloy using micro-electrochemical spark processing, according to an embodiment of the present invention.
[0025] The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures. Optional portions of the figures may be illustrated using dashed or dotted lines, unless the context of usage indicates otherwise.
DETAILED DESCRIPTION
[0026] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the scope of the invention as defined in the claims.
[0027] In any embodiment described herein, the open-ended terms "comprising", "comprises”, and the like (which are synonymous with "including", "having” and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of", “consists essentially of", and the like or the respective closed phrases "consisting of", "consists of”, the like.
[0028] As used herein, the singular forms “a”, “an”, and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.
[0029] FIG. 1 illustrates a schematic view of a system 100 for surface modification of a titanium alloy, according to an embodiment of the present invention. In an embodiment of the present invention, the system 100 may be adapted to perform surface modification of a titanium alloy through a micro-electrochemical spark process that combines electrochemical reactions and localized spark discharges in a urea-modified alkaline electrolyte. The system 100 may further be adapted to effectively modify surface properties of the titanium alloy at the micron level without requiring extensive equipment or high temperatures.
[0030] The system 100 may comprise non-limiting components that may include a container 102 adapted to hold a urea-modified alkaline electrolyte, a cathodic electrode 104, an anodic titanium alloy workpiece 106, and a pulsed power supply 108.
[0031] The container 102 may be adapted to maintain an electrolyte solution containing potassium hydroxide (KOH) and urea. The container 102 may be made of a chemically resistant and electrically insulating material such as glass, polymeric composites, or ceramic, to prevent any unwanted reactions with the electrolyte. The container 102 may be dimensioned to accommodate the spacing between the cathodic electrode 104 and the anodic titanium alloy workpiece 106. The container 102 may further be adapted to allow circulation or stirring of the electrolyte to maintain homogeneity during processing. The container 102 may also include provisions for temperature monitoring or control to ensure stable operating conditions.
[0032] The cathodic electrode 104 may comprise a brass rod, in an embodiment of the present invention. In another embodiment of the present invention, the cathodic electrode 104 may comprise copper, stainless steel, or other conductive alloys that can withstand spark discharges in the electrolyte. In yet another embodiment of the present invention, the cathodic electrode 104 may be coated with conductive materials to enhance durability and reduce erosion. In some embodiments of the present invention, the cathodic electrode 104 may be replaceable or interchangeable to allow flexibility in processing different titanium alloy workpieces. In another embodiment of the present invention, the cathodic electrode 104 may be shaped as a cylindrical rod, a flat plate, or a pointed tip, depending on the desired spark intensity and coating distribution.
[0033] The cathodic electrode 104 may be connected to a negative terminal of the pulsed power supply 108, and the anodic titanium alloy workpiece 106 may be connected to the positive terminal of the pulsed power supply 108. The cathodic electrode 104 may be shaped as a rod to enable localized spark discharges. The cathodic electrode 104 may be formed of brass, which contributes copper (Cu) and zinc (Zn) ions to the electrolyte during erosion. The cathodic electrode 104 may be dimensioned to have a diameter in the range of 0.9-1.1 millimeters. The cathodic electrode 104 may further be replaceable or adjustable in position to regulate the spark gap distance.
[0034] In an embodiment of the present invention, the cathodic electrode 104 may be cylindrical in shape and aligned vertically or horizontally with respect to the anodic titanium alloy workpiece 106. The electrode surface may be polished to ensure uniform spark discharge and consistent ion release into the electrolyte during processing.
[0035] In an embodiment of the present invention, the anodic titanium alloy workpiece 106 may be formed of titanium alloy Ti-6Al-4V (Ti64). The anodic titanium alloy workpiece 106 may be positioned such that its surface is exposed to the electrolyte for coating formation. The anodic titanium alloy workpiece 106 may be of commercial grade and may be prepared by surface cleaning and polishing prior to processing to remove contaminants and oxides.
[0036] The anodic titanium alloy workpiece 106 may be dimensioned according to the desired application, for example, biomedical implants, aerospace components, or automotive parts. The anodic titanium alloy workpiece 106 may serve as a base material on which a coating of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds is formed, thereby enhancing hardness, wear resistance, and scratch resistance compared to the uncoated alloy. The anodic titanium alloy workpiece 106 may, after coating, exhibit hardness values of at least 850 Vickers hardness (HV), relative to approximately 200 HV prior to surface modification.
[0037] The pulsed power supply 108 may be adapted to apply a pulsed direct current (DC) voltage in the range of 45-55 volts at a frequency in the range of 9-11 kilohertz (kHz) and a duty factor in the range of 35-45%.
[0038] The pulsed power supply 108 may be further adapted to enable the generation of micro-electrochemical sparks between the cathodic electrode 104 and the anodic titanium alloy workpiece 106 by rupturing a gas film formed of hydrogen and oxygen bubbles at an electrode-electrolyte interface. The pulsed power supply 108 may be programmable to allow adjustment of voltage, frequency, and duty cycle parameters to control coating thickness, microstructure, and uniformity. The pulsed power supply 108 may also include monitoring circuitry for maintaining stable operating conditions during the micro-electrochemical spark process.
[0039] FIG. 2A illustrates an optical image 200 of a coated surface compared to a base uncoated surface of the titanium alloy, according to an embodiment of the present invention. In an embodiment of the present invention, the coated surface may appear smoother and more uniform than the base surface. In another embodiment of the present invention, the contrast between the coated and uncoated regions may indicate successful surface modification. The optical image may also show that the coating is continuous and adheres well to the substrate.
[0040] FIG. 2B illustrates a field emission scanning electron microscope (FESEM) top-view image 202 of the coating formed on the titanium alloy, according to an embodiment of the present invention. In an embodiment of the present invention, the FESEM top-view may reveal a dense and compact layer on the titanium alloy surface. The surface may exhibit uniformly distributed micro-particles and fine structures. In another embodiment of the present invention, the image may show limited surface porosity, indicating good coating integrity. The uniformity of the coating suggests that the micro-electrochemical spark process is well-controlled.
[0041] FIG. 2C illustrates a FESEM cross-sectional image 204 of the coating formed on the titanium alloy, according to an embodiment of the present invention. In an embodiment of the present invention, the cross-section may show a coating thickness in the range of 15-25 micrometers (µm). The image may also reveal a strong metallurgical bond between the coating and the titanium alloy substrate. In another embodiment of the present invention, the interface may be free from significant cracks or delamination. This indicates stable adhesion of the coating under processing conditions.
[0042] FIG. 2D illustrates hardness test results showing optical images 206 of indentations on the base surface and the coated surface of the titanium alloy, according to an embodiment of the present invention. In an embodiment of the present invention, the indentation on the coated surface may be significantly smaller than that on the base surface. This may demonstrate an increase in hardness from approximately 200 Vickers hardness (HV) in the base alloy to at least 850 HV in the coated alloy. In another embodiment of the present invention, the test may also confirm uniform hardness across the coated surface.
[0043] FIG. 2E illustrates energy dispersive spectroscopy (EDS) analysis results 208 of the coated titanium alloy surface, according to an embodiment of the present invention. In an embodiment of the present invention, the EDS spectrum may confirm the presence of titanium (Ti), oxygen (O), nitrogen (N), copper (Cu), and zinc (Zn). In another embodiment of the present invention, the results may show that these elements are uniformly distributed throughout the coating. The detection of nitrogen, oxygen, and copper-zinc elements may indicate the formation of TiN, TiO₂, and CuTiZn compounds during processing.
[0044] FIG. 2F illustrates X-ray diffraction (XRD) analysis results 210 depicting formation of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds in the coating, according to an embodiment of the present invention. In an embodiment of the present invention, the XRD peaks may validate the crystalline phases formed during the micro-electrochemical spark process. In another embodiment of the present invention, the results may confirm that the coating contains hard ceramic-like phases such as TiN and TiO₂, in combination with intermetallic phases such as CuTiZn. The XRD analysis may therefore support both chemical and structural modification of the titanium alloy surface.
[0045] FIG. 2G illustrates scratch test results 212, according to an embodiment of the present invention. In an embodiment of the present invention, the scratch test may compare the base titanium alloy surface with the coated surface. In another embodiment of the present invention, the optical and three-dimensional (3D) profiles may show that the coated surface exhibits shallower grooves and reduced damage compared to the uncoated surface. In an embodiment of the present invention, the scratch depth on the coated surface may be significantly less, indicating improved scratch resistance due to the formation of the titanium nitride (TiN), the titanium oxide (TiO₂), and the copper-titanium-zinc (CuTiZn) compounds.
[0046] FIG. 2H illustrates wear test results 214, according to an embodiment of the present invention. In an embodiment of the present invention, the wear test may demonstrate reduced material loss in the coated titanium alloy workpiece compared to the uncoated workpiece. In another embodiment of the present invention, the 2D and 3D wear track images may reveal narrower and shallower wear paths on the coated surface. In an embodiment of the present invention, the results may confirm that the coating provides enhanced wear resistance and prolongs the service life of titanium alloy components under mechanical stress.
[0047] FIG. 3 depicts a flowchart of a method 300 for surface modification of a titanium alloy using micro-electrochemical spark processing, according to an embodiment of the present invention.
[0048] At step 302, the container 102 may be prepared with a urea-modified alkaline electrolyte, according to an embodiment of the present invention. In an embodiment of the present invention, the electrolyte may comprise potassium hydroxide (KOH) in the range of 18-22 weight percentage (wt.%) and urea in the range of 4-6 wt.%. The container 102 may hold the electrolyte in a stable condition, and the solution may be mixed thoroughly to ensure homogeneity.
[0049] At step 304, the cathodic electrode 104 and the anodic titanium alloy workpiece 106 may be positioned inside the container 102, according to an embodiment of the present invention. In a preferred embodiment of the present invention, the cathodic electrode 104 may comprise a brass rod connected to the negative terminal of the pulsed power supply 108. The anodic titanium alloy workpiece 106 may be connected to the positive terminal of the pulsed power supply 108. A controlled gap may be maintained between the cathodic electrode 104 and the anodic titanium alloy workpiece 106 to enable localized spark initiation.
[0050] At step 306, a pulsed direct current (DC) potential may be applied between the cathodic electrode 104 and the anodic titanium alloy workpiece 106 using the pulsed power supply 108, according to an embodiment of the present invention. In an embodiment of the present invention, the pulsed power supply 108 may apply a voltage in the range of 45-55 volts, a frequency in the range of 9-11 kilohertz (kHz), and a duty factor in the range of 35-45%. This potential may initiate localized spark discharges in the electrolyte.
[0051] At step 308, the localized sparks may rupture a gas film formed by hydrogen and oxygen bubbles at the electrode-electrolyte interface between the cathodic electrode 104, the anodic titanium alloy workpiece 106, and the electrolyte in the container 102, according to an embodiment of the present invention. In an embodiment of the present invention, rupture of the gas film may allow molten material from the anodic titanium alloy workpiece 106 to mix with ions released from the electrolyte and ions eroded from the cathodic electrode 104.
[0052] At step 310, a coating may be formed on the surface of the anodic titanium alloy workpiece 106, according to an embodiment of the present invention. In an embodiment of the present invention, the coating may comprise the titanium nitride (TiN), the titanium oxide (TiO₂), and the copper-titanium-zinc (CuTiZn) compounds. The coating may have an average thickness in the range of 15-25 micrometers (µm). In another embodiment of the present invention, the anodic titanium alloy workpiece 106 may exhibit an increase in hardness from approximately 200 Vickers hardness (HV) before coating to at least 850 HV after coating. The coating may further improve a wear resistance and a scratch resistance of the titanium alloy workpiece 106.
[0053] While the invention has been described in connection with what is presently considered to be the most practical and various embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
[0054] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined in the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements within substantial differences from the literal languages of the claims. , Claims:CLAIMS
I/We Claim:
1. A system (100) for surface modification of a Titanium alloy, comprising:
a container (102) adapted to hold a urea-modified alkaline electrolyte;
a cathodic electrode (104);
an anodic Titanium alloy workpiece (106); and
a pulsed power supply (108) adapted to apply a pulsed direct current (DC) voltage in the range of 45-55 volts at a frequency in the range of 9-11 kilohertz (kHz) and a duty factor in the range of 35-45% between the cathodic electrode (104) and the anodic Titanium alloy workpiece (106),
wherein the system (100) is adapted to generate micro-electrochemical sparks for forming a coating comprising at least one of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds on a surface of the anodic Titanium alloy workpiece (106).
2. The system (100) as claimed in claim 1, wherein the urea-modified alkaline electrolyte comprises potassium hydroxide (KOH) in the range of 18-22 weight percentage (wt.%) and urea in the range of 4-6 wt.%.

3. The system (100) as claimed in claim 1, wherein the cathodic electrode (104) has a diameter in the range of 0.9-1.1 millimeters.

4. The system (100) as claimed in claim 1, wherein the formed coating has an average thickness in the range of 15-25 micrometers (µm).

5. The system (100) as claimed in claim 1, wherein, upon coating, the anodic Titanium alloy workpiece (106) exhibits a hardness of at least 850 Vickers hardness (HV) relative to approximately 200 HV of the anodic Titanium alloy workpiece (106) prior to the coating.

6. A method (300) for surface modification of a Titanium alloy, the method (300) comprising:
placing a cathodic electrode (104) and an anodic Titanium alloy workpiece (106) in a urea-modified alkaline electrolyte within a container (102);
applying a pulsed direct current (DC) potential using a pulsed power supply (108) between the cathodic electrode (104) and the anodic Titanium alloy workpiece (106) to generate localized sparks; and
forming a coating on the anodic Titanium alloy workpiece (106) through electrochemical and spark-induced reactions, wherein the coating comprises at least one of titanium nitride (TiN), titanium oxide (TiO₂), and copper-titanium-zinc (CuTiZn) compounds.
7. The method (300) as claimed in claim 6, wherein the electrolyte comprises potassium hydroxide (KOH) in the range of 18-22 weight percentage (wt.%) and urea in the range of 4-6 wt.%.

8. The method (300) as claimed in claim 6, wherein the pulsed direct current (DC) has a voltage in the range of 45-55 volts, a frequency in the range of 9-11 kHz, and a duty factor in the range of 35-45%.

9. The method (300) as claimed in claim 6, wherein the formed coating has an average thickness in a range of 15-25 µm.

10. The method (300) as claimed in claim 6, wherein discharge of the generated localized sparks rupture a gas film formed by hydrogen (H₂) and oxygen (O₂) bubbles to mix molten material of the Titanium alloy with ions from the electrolyte and the cathodic electrode (104) for coating formation.

Date: September 02, 2025
Place: Noida

Nainsi Rastogi
Patent Agent (IN/PA-2372)
Agent for the Applicant