Porous Oxide for Improving Titanium-Polymer Bonding

Abstract

Chemical treatment methods have been identified as a simple and effective means of improving the bonding between injection-molded polymers and titanium surfaces. This method forms an oxide layer on the titanium surface, which includes layered double hydroxides. The layered double hydroxides both increase the bonding strength and minimize air or water leakage. This method enables the use of titanium alloys combined with injection-molded polymer structures in robust, lightweight, and waterproof enclosures for consumer electronics.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 261,412, filed Sep. 20, 2021, entitled “POROUS OXIDE FOR IMPROVED TITANIUM-POLYMER BONDING,” and U.S. Non-Provisional Patent Application No. 17 / 656,395, filed Mar. 24, 2022. The entire disclosures of the above U.S. provisional patent application and non-provisional patent application are incorporated herein by reference in their entireties. Technical Field

[0003] The described embodiments generally relate to surface structures on titanium surfaces. More specifically, embodiments of the present invention relate to systems and methods for forming an interlocking structure at a titanium surface to attach a polymeric material to the titanium surface. Background Art

[0004] Housings for consumer devices are typically constructed from a combination of metallic and non-metallic materials to provide enhanced functionality, structure, and appearance. However, metals (such as titanium) that exhibit properties favorable for use in consumer devices may lack the natural ability to attach to these non-metallic materials. Techniques for modifying metals to facilitate attachment to non-metallic materials can be quite time-consuming, costly, and labor-intensive. Additionally, although these techniques can attach non-metallic materials to metallic materials, they may not provide the necessary amount of pull strength between titanium and non-metallic materials.

[0005] Furthermore, certain metals can be etched and / or anodized to provide improved adhesion; however, no comparable method exists for titanium. The state-of-the-art etching and surface treatment methods for titanium (such as those for bone integration in medical implants and high surface area catalysts) only produce scalloped textures (without undercuts) or spongy textures. Unlike the anodization of aluminum and / or steel, the anodization of titanium typically produces a non-porous oxide that plays only a relatively small role in improving polymer adhesion. Porous oxides can be formed on titanium by micro-arc oxidation or by anodization in a fluoride-based electrolyte, as well as by anodization in a caustic solution, but such oxides are generally brittle and / or poorly adherent and thus can hardly promote the adhesion bonding of injection-molded structural polymers. Summary of the Invention

[0006] This document describes various embodiments related to oxides formed on a titanium surface. Additionally, this document includes embodiments related to techniques for etching the surface of a metal component including titanium. Specifically, various embodiments relate to systems and methods for forming an interlocking structure at the surface of a titanium component to attach a polymeric material to the surface of a metal component including titanium.

[0007] According to some embodiments, the oxide layer located on the titanium surface may include layered double hydroxide. In some examples, the titanium surface includes a titanium alloy. In some embodiments, the oxide layer has a thickness of from about 30 nm to about 70 nm. In some examples, the oxide layer may have a porosity between about 30% and about 80%. In some examples, the layered double hydroxide includes a microstructure that includes plates having a thickness of less than about 10 nm and a length of from about 10 nm to about 100 nm and an angle of from about 30° to about 90° with respect to the titanium surface. In some examples, the oxide layer may include a first plate and a second plate. The ends of the first plate and the second plate may be separated by a distance between about 20 nm and about 80 nm. The oxide layer may further include a porous structure, wherein the pores of the porous structure have a diameter of from about 20 nm to about 50 nm. [[ID=[4]]

[0008] According to some embodiments, a titanium-polymer interface may include an oxide layer located on the titanium surface, and a polymer. In some examples, the oxide layer and the polymer may form a titanium-polymer bond having a bond strength of about 28 MPa or greater. In some embodiments, the oxide layer may include layered double hydroxide. In some examples, the polymer may include at least one of a glass-filled PBT resin, a polyamide, and an epoxy resin.

[0009] In some examples, the titanium surface may include a chemically etched surface. The chemically etched surface may be etched with sulfuric acid. In some examples, the polymer may include an injection-molded polymer. In some examples, the titanium-polymer interface may include a polymer having a dynamic viscosity of from about 100 cp to about 1×10 6 cp.

[0010] According to some embodiments, the porous oxide layer formed on the titanium surface may include plates that extend from the surface oxide layer to the ends of the plates, with a length of about 10 nm to about 100 nm. In some examples, the porous oxide layer may include a first plate and a second plate. The distance from the end of the first plate to the end of the second plate may be between about 20 nm and about 80 nm. In some examples, the porous oxide layer may have a thickness between about 30 nm and about 70 nm. In some examples, the oxide layer may have a porosity between about 30% and about 80%. In some embodiments, the plates may have a thickness of about 10 nm. In some examples, the plates may be at an angle of about 30° to about 90° relative to the titanium surface.

[0011] Other aspects and advantages of the present disclosure will become apparent from the following description taken in conjunction with the drawings which illustrate, by way of example, the principles of the described embodiments.

[0012] The present summary is provided only for the purpose of summarizing some example embodiments in order to provide a basic understanding of some aspects of the subject matter described herein. Accordingly, it should be understood that the above features are merely examples and should not be construed in any way as narrowing the scope or essence of the subject matter described herein. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following detailed description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals refer to like structural elements, and wherein:

[0014] Figure 1 A perspective view of various electronic devices having a metal surface that can be processed using the techniques described herein according to some embodiments is shown.

[0015] Figure 2 An exploded view of the components of the electronic device is shown.

[0016] Figure 3A A cross-sectional view of a titanium surface including an oxide layer is shown.

[0017] Figures 3B to 3D An exemplary image of a view of a titanium surface having an oxide layer formed using the techniques described herein according to some embodiments is shown.

[0018] Figure 4A A method of forming a layered double hydroxide film layer on a titanium surface according to some embodiments is shown.

[0019] Figure 4B An exemplary image of a view of an etched titanium surface formed using the techniques described herein according to some embodiments is shown.

[0020] Figure 5 shows a graph depicting the relationship between an anodization treatment method according to some examples and the tensile strength of the treated metal part. Detailed Description

[0021] Reference will now be made specifically to representative embodiments shown in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. Instead, it is intended to cover alternative forms, modifications, and equivalents that may be included within the spirit and scope of the described embodiments as defined by the appended claims.

[0022] The following disclosure relates to chemical treatment methods that provide effective means for improving the bonding of polymers to titanium surfaces. Titanium has a very high specific strength and is thus a particularly suitable metal for certain engineering applications. For example, this enables the manufacture of strong but lightweight housings for portable electronic devices. In any such application, bonding to other materials such as polymers, glass, ceramics is necessary. Specifically, injection-molded polymers can be used to electrically isolate the various components of the housing while ideally maintaining structural strength. This document includes chemical methods for producing thin and rough surface oxides on titanium, which significantly improve the adhesion of polymers to titanium.

[0023] In one specific embodiment, once the final geometry of the titanium surface has been prepared for adhesive bonding, the titanium can optionally be etched to increase its roughness. Unlike aluminum or steel, the options for roughening are limited because titanium is insensitive to many chemical etchants. After etching, in the chemical method described in more detail below, a surface structure can be produced on titanium or a titanium alloy onto which a structural polymer such as glass-filled ABS can be injection-molded, and the resulting bond strength is similar to that achieved with steel and aluminum, and the air leakage rate through the bond in a leak test is similarly low.

[0024] Reference is made below to Figures 1 to 5Let's discuss these embodiments and other embodiments. However, those skilled in the art will readily understand that the detailed description given herein with respect to these figures is for illustrative purposes only and should not be construed as limiting. Additionally, as used herein, a system, method, article of manufacture, component, feature, or sub-feature that includes at least one of a first option, a second option, or a third option should be understood to refer to a system, method, article of manufacture, component, feature, or sub-feature that can include one of each of the listed options (e.g., only one first option, only one second option, only one third option), multiple of a single listed option (e.g., two or more first options), two options simultaneously (e.g., one first option and one second option), or a combination thereof (e.g., two first options and one second option).

[0025] Titanium is often considered the material of choice for consumer-grade portable electronic devices. Titanium has desirable properties such as high specific strength and stiffness and is relatively easy to machine. Additionally, titanium can be anodized to produce a wide range of durable and aesthetically pleasing finishes that resist degradation due to daily handling. Titanium can be used in combination with non-metallic materials such as glass and polymers. For example, the display of a portable electronic device can be incorporated into a titanium frame of the housing. The titanium frame is typically subdivided into various electrically isolated components in order to prevent electromagnetic interference to antennas carried within the housing. For example, titanium can be used to form a structural band around the edge of the housing such that the display is incorporated into one face and glass is incorporated into the opposite face. Additionally, electrically insulating cracks can be formed around the perimeter of the housing.

[0026] To endow the structure band with sufficient structural strength, robustness, rigidity, heat resistance, and moisture resistance throughout the lifespan of the housing, a strong adhesive bond needs to be formed between a metal (e.g., titanium) and a non-metal material (e.g., a polymer). Meeting these requirements can be even more technically challenging in the face of additional insulation cracks (for improving antenna performance) and even smaller adhesion areas (to minimize weight and space). Additionally, the growing demand for waterproof housings requires that these adhesive bonds not only maintain strength but also prevent moisture leakage, even after the housing has undergone many strain cycles. Furthermore, it should be noted that due to the requirement of electrical isolation between metal components, conventional mechanisms for fastening metals to non-metal materials (such as mechanical fasteners (e.g., rivet guns)) cannot be used in portable electronic devices. For example, non-metal materials (such as polymers) are used to electrically isolate different metal components attached together. Additionally, alternative methods (such as micro-arc oxidation or anodization in a fluoride-based electrolyte or caustic solution) typically result in poor adhesion performance. In fact, these methods produce slightly scalloped structures that cannot provide the necessary attachment strength, waterproofness, and tensile strength required for portable electronic devices to withstand consumer use in harsh environments. As the housings of portable electronic devices become smaller and / or the designs of these housings change to just a peripheral metal band, the allowable bonding area between the metal and the non-metal is greatly reduced. Therefore, more emphasis is placed on a more robust metal-non-metal bond.

[0027] As used herein, the terms “oxide coating,” “oxide layer,” “oxide film,” “oxide layer,” “porous oxide layer,” and “surface oxide layer” may be used interchangeably and refer to any suitable oxide layer. The oxide layer is formed on the surface of a titanium substrate. The titanium substrate may include any of a number of suitable alloys. The type of titanium may include any number of examples, such as Ti-6Al-4V (Ti6Al4V) type alloys. In some embodiments, the non-metal layer may include mostly non-metal material mixed or combined with a metal material such that the non-metal layer is primarily composed of non-metal material. As used herein, the terms “component,” “layer,” “section,” and “portion” may also be used interchangeably, where appropriate.

[0028] These embodiments and other embodiments are discussed below with reference to Figures 1 to 5 However, those skilled in the art will readily understand that the detailed description given herein with respect to these figures is for illustrative purposes only and should not be construed as limiting.

[0029] Figure 1Shows various portable electronic devices that can be processed using the techniques described herein. The techniques as described herein can be used to process the metal surface (e.g., titanium oxide layer, etc.) of the housing of portable devices for consumer use. Figure 1 Illustrates a smart phone 102, a tablet computer 104, a smart watch 106, and a portable computer 108. According to some embodiments, the metal surface can refer to a metal substrate covered by a metal oxide layer. In some examples, the metal oxide layer can be formed from the metal substrate. Specifically, the metal oxide layer can be used as an additional protective coating to protect the metal substrate, for example, when these portable devices are dropped, scratched, chipped, or worn.

[0030] According to some embodiments, a non-metallic material can be attached to the outer surface of the metal surface. Specifically, the multi-layer housing of these portable devices including a combination of metal materials and non-metallic materials can provide improved structural benefits and reduced electromagnetic interference benefits for the functions of these portable devices. In one example, these portable devices can include a wireless antenna / transceiver capable of receiving and transmitting data signals with other electronic devices. However, the metal surface directly covering the wireless antenna may cause a large amount of undesired electromagnetic interference, which may affect the ability of the portable device to receive and / or transmit these data signals. However, non-metallic materials (such as polymers) are generally non-conductive (i.e., have dielectric properties), so the amount of electromagnetic interference affecting the portable device can be minimized while still imparting a sufficient amount of structural rigidity and protection quality to the housing of the portable device.

[0031] Figure 2 Shows an exploded view of a band 202 that can form part of the housing or enclosure of an electronic device (such as Figure 1 the electronic devices 102 to 108 described therein). The band 202 can include one or more parts that are titanium or titanium alloy components, such as an outer part joined to an inner part, as described herein. For example, the band 202 can include a first titanium sidewall component 204, a second titanium sidewall component 206, a third titanium sidewall component 208 (opposite the first composite sidewall component 204), and a fourth titanium sidewall component 210. In some cases, as described herein, by way of non-limiting example, the titanium components 204, 206, 208, 210 can be separated and / or joined together by a material that can include an electrically inert or electrically insulating material (such as a polymer and / or resin).

[0032] Although Figure 2The illustrated embodiments include a band 202 having a plurality of titanium components 204, 206, 208, 210 joined together, but in some embodiments, as described herein, the housing or enclosure for an electronic device may include or be formed from a single titanium component having an interior portion and an exterior portion. Additionally, in some examples, these titanium components may form portions of the housing or enclosure other than the sidewalls, such as the top portion, bottom portion, or any portion of the housing or enclosure. The titanium components 204, 206, 208, 210 of the band 202 may be formed by a variety of methods and may allow the band 202 to have a detailed shape or design that is specifically tailored to meet one or more needs, such as interior dimensional requirements, without the need for additional features to enhance the structure of the band.

[0033] An opening or crack region may separate adjacent titanium components of the band 202. For example, sidewall component 208 is separated from sidewall component 210 by an opening 212. Sidewall component 208 is separated from sidewall component 206 by an additional opening. A non-metallic spacer 214 may fill each opening. In some examples, the non-metallic spacer 214 may include a polymer. The polymer may be at least one of an injection-molded glass-filled PBT resin, a polyamide, and an epoxy resin. In some examples, the polymer may be bonded to the titanium component with a titanium-polymer bonding operation. Further details regarding the titanium components and methods for improving the bond strength of the titanium-polymer bond are provided below with reference to Figures 3A to 5 provide further details of the titanium components and methods for improving the bond strength of the titanium-polymer bond.

[0034] Figure 3A A cross-sectional view of a titanium surface 300 is shown. The titanium surface 300 includes a titanium substrate 302 and an oxide layer 304. The titanium substrate 302 may be a titanium alloy. In some examples, the oxide layer 304 may include a thickness greater than about 25 nm. In some embodiments, the thickness of the oxide layer 304 may be about 30 nm or greater, about 40 nm or greater, about 50 nm or greater, about 60 nm or greater, about 70 nm or greater, about 80 nm or greater, or in the range of about 25 nm to about 35 nm, about 35 nm to about 50 nm, about 50 nm to about 60 nm, or about 60 nm to about 70 nm.

[0035] In some examples, the titanium surface includes a layered double hydroxide. A layered double hydroxide (LDH) is an ionic layered compound composed of positively charged layers and an interlayer region having charge-compensating anions. Layered double hydroxides typically consist of a mixed metal (e.g., a titanium alloy) and hydroxide molecules separated by exchangeable anions. In some examples, the oxide layer 304 may include a microstructure 306 having plates 308. The plates 308 may include a layered double hydroxide.

[0036] In some examples, the thickness of the plate 308 can be less than about 10 nm and the length can be from about 10 nm to about 100 nm. In some embodiments, the thickness of the plate 308 can be about 2 nm or greater, about 3 nm or greater, about 5 nm or greater, about 7 nm or greater, about 8 nm or greater, about 9 nm or greater, or in the range of about 1 nm to about 3 nm, about 3 nm to about 6 nm, about 6 nm to about 8 nm, or about 8 nm to about 10 nm.

[0037] In some embodiments, the oxide layer 304 can include a plate that extends a certain length from the oxide layer 304 to the end 310 of the plate 308. The length of the plate 308 can be about 10 nm or greater, about 20 nm or greater, about 30 nm or greater, about 40 nm or greater, about 50 nm or greater, about 60 nm or greater, about 70 nm or greater, about 80 nm or greater, about 90 nm or greater, or in the range of about 10 nm to about 20 nm, about 20 nm to about 30 nm, about 30 nm to about 40 nm, about 40 nm to about 50 nm, about 50 nm to about 60 nm, about 60 nm to about 70 nm, about 70 nm to about 80 nm, about 80 nm to about 90 nm, or about 90 nm to about 100 nm. In some examples, the plate 308 can be at an angle θ greater than about 30° with respect to the titanium surface 300. The plate can be at an angle θ of about 40° or greater, about 50° or greater, about 60° or greater, about 70° or greater, about 80° or greater, or in the range of about 30° to about 40°, about 40° to about 50°, about 50° to about 60°, about 60° to about 70°, about 70° to about 80°, or about 80° to about 90° with respect to the titanium surface 300.

[0038] In some examples, the microstructure 306 extending from the oxide layer 304 can include a first plate 308 and a second plate 312. In some embodiments, the first plate 308 and the second plate 312 can extend independently from the oxide layer 304. In other embodiments, the first plate 308 and the second plate 312 can extend from substantially the same spatial position of the oxide layer 304, as Figure 3AAs shown. The first plate 308 and the second plate 312 can each include an end 310. In some examples, the end 310 of the first plate 308 and the end 310 of the second plate 312 can be separated by a distance 314. The distance 314 can cause the oxide layer to form a porous structure, or in other words, form a porous oxide layer. In some embodiments, the distance from the end 310 of the first plate 308 to the end 310 of the second plate 312 can be between about 20 nm and about 80 nm. The distance 314 can be about 20 nm or greater, about 30 nm or greater, about 40 nm or greater, about 50 nm or greater, about 60 nm or greater, about 70 nm or greater, about 80 nm or greater, or within the range of about 20 nm to about 30 nm, about 30 nm to about 40 nm, about 40 nm to about 50 nm, about 50 nm to about 60 nm, about 60 nm to about 70 nm, or about 70 nm to about 80 nm. As described below, the porous structure of the oxide layer 304 generated at least by the first plate 308 and the second plate 312 can cause an interlocking structure to be generated by the non-metallic material (such as a polymer) when the non-metallic material flows into the porous structure and is allowed to harden from a molten state and transform into a solid state.

[0039] Figures 3B to 3D Shows an exemplary micrograph of an exemplary titanium surface according to some embodiments, the exemplary titanium surface having a layered double hydroxide similar to that shown in Figure 3A as the titanium substrate 302 and the oxide layer 304, the oxide layer 304 having a layered double hydroxide as plates 308 extending from the oxide layer. Figure 3B Shows a cross-sectional view in which the oxide layer 304 appears as a layered double hydroxide. As Figure 3B shown, the plates extend from the oxide layer and have different angles of about 30° to about 90° with respect to the titanium surface. The ends of the plates have a corresponding distance between them, thereby forming pores because the ends are separated by a distance of about 20 nm to about 80 nm. Figure 3C Shows a top view of a region of the oxide layer formed on the outer surface of the exemplary titanium substrate. Specifically, Figure 3C shows an arrangement of a plurality of plates extending from the oxide layer, the distance between the ends of the plurality of plates defining an opening that forms a porous structure. Figure 3D Also shows an arrangement of a plurality of plates extending from the oxide layer. However, Figure 3DMore clearly shows that the porous structure formed in the oxide layer can present pores having a certain size range, where the distance from the end of the plate can be up to about 50 nm. In some embodiments, the oxide layer can include a porosity between about 30% and about 80%. In some embodiments, the oxide layer can include a porosity of about 50%. In some embodiments, the porosity of the oxide layer can be 30% or greater, such as about 40% or greater, about 50% or greater, about 60% or greater, about 65% or greater, about 70% or greater, or in the range of about 30% to about 40%, about 40% to about 50%, about 50% to about 60%, about 60% to about 70% or about 70% to about 80%. In some embodiments, the oxide layer (e.g., oxide layer 304) can include a porous structure, where the pores of the porous structure include a diameter of about 20 nm to about 80 nm. In some examples, the porosity of the oxide layer can be adjusted according to the method of forming a layered double hydroxide film layer on the titanium surface.

[0040] Figure 4A Shows method 400 for forming a layered double hydroxide film layer on a titanium surface according to some embodiments. As Figure 4A shown, method 400 can optionally start at block 402, where the titanium surface can be etched to provide a roughening effect. In some examples, before roughening the surface of the titanium, the oil stain on the substrate can be removed and rinsed. After rinsing, the titanium surface can be dried to prepare for etching. In some examples, etching the titanium surface can include immersing the titanium surface in sulfuric acid. Different from aluminum or steel, the choice of roughening itself is limited because titanium is insensitive to many chemical etchants. However, sulfuric acid provides a useful roughening effect. Specifically, etching the surface can be beneficial to provide a rough outer surface of the titanium substrate, which can promote the growth of the titanium oxide layer at the roughened area.

[0041] Now refer to Figure 4B , the titanium can be chemically etched to increase its roughness. Figure 4B Shows an exemplary micrograph of the titanium substrate after being etched with sulfuric acid. In some examples, the sulfuric acid etching method can provide a bonding strength of up to about 15% between the titanium oxide and the non-metallic material. In other embodiments, the sulfuric acid etching method can be omitted and / or replaced with other physical or chemical roughening pretreatment methods. In some embodiments, the etching method can provide a peak-valley roughness greater than about 20 microns. In some embodiments, the difference in height of each point on the surface compared to the arithmetic mean of the surface can be increased from less than about 1 μm to greater than about 4 μm. In some embodiments, the percentage of the additional surface area contributed by the surface texture compared to the planar defined area can be between about 5% and about 13%.

[0042] In one example, computer numerical control (CNC) machining can be used to prepare the roughened surface. In some embodiments, the structural design for improving the bond between the titanium surface and the non-metallic material can include macro features (e.g., mechanical interlocking) that can provide mechanical bonding between the non-metallic material (e.g., polymer) and titanium, maximize the surface area for titanium-polymer bonding, and provide various interface orientations to optimize the strength and robustness of the joint against the expected failure modes. Any etching or features including improved bonding can also help to maximize the length and tortuosity of any potential air or water leakage paths and provide a stronger bond against air and water leakage.

[0043] Referring back to Figure 4A , at block 404, after removing the titanium surface from the sulfuric acid, it can be rinsed and dried. In some examples, the etched titanium surface can be subjected to a two-stage countercurrent rinse to remove the etchant solution before immersing the titanium surface in the hydroxide bath. In some examples, the outer surface of the titanium substrate can be cleaned to remove any liquids or contaminants that may be present, thereby further facilitating the formation of an oxide layer over the titanium substrate. For example, the outer surface of the titanium substrate can be cleaned and rinsed with tap water or deionized water to remove any residual sulfuric acid. In one embodiment where the titanium surface is not etched, the surface can simply be cleaned and prepared before immersing the titanium surface in the hydroxide bath.

[0044] At block 406, the titanium surface can be immersed in a hydroxide bath. In some examples, the bath can have a pH of about 12 to about 14 and a temperature of about 25 °C to about 125 °C. The hydroxide can include at least one of sodium hydroxide, calcium hydroxide, and potassium hydroxide. The hydroxide oxidizes the titanium, generating a relatively thin and well-adhering surface oxide. In some embodiments, the hydroxide attaches the oxide as it forms, thereby etching and roughening the oxide layer to form a fine-scale roughness and porosity including layered double hydroxide plates. The porosity improves the adhesion of the injection-molded polymer to the oxide surface.

[0045] At block 408, the titanium surface can optionally be anodized while immersed in the hydroxide. In some examples, a positive potential can be applied to the titanium substrate to promote oxide growth. A titanium or carbon counter electrode can be utilized. In one example, anodizing the titanium surface can include applying a 15 V potential to the titanium surface. In some embodiments, anodizing in addition to the hydroxide bath can form an oxide with a greater thickness and / or higher porosity than when no anodizing is performed.

[0046] At block 410, the titanium surface can be rinsed and then dried. Similar to block 404 discussed above, the outer surface of the titanium substrate can be cleaned to remove any liquids or contaminants that may be present, thereby improving the bond strength between the oxide layer and the non-metallic material (such as a polymer). At block 412, method 400 can include injection molding a polymer. In one example, a structural polymer such as glass-filled ABS can be injection molded, resulting in a bond strength of about 28 MPa. As discussed above, with reference to Figure 3A , after forming an oxide layer including layered double hydroxide, the metal oxide layer can include pores that can be filled with a non-metallic material. For example, the non-metallic material can refer to a polymer material such as polyethylene terephthalate ("PET"), polyaryletherketone ("PAEK"), polyetheretherketone ("PEEK"), injection molded glass-filled PBT resin, polyamide, and / or epoxy resin, which can be allowed to flow into the pores and / or the distance between the ends of the plurality of plates of the oxide layer in a molten state or a liquid state. In some examples, the polymer can have any amount of viscosity or surface tension sufficient to attach to the oxide layer on the titanium surface. In some examples, the titanium-polymer interface includes a polymer having a viscosity of about 100 cp to about 1×10 6 cp. In some embodiments, the polymer viscosity can be about 8×10 4 cp. In some embodiments, the polymer viscosity can be about 100 cp or greater, such as about 500 cp or greater, about 1000 cp or greater, about 5000 cp or greater, about 1×10 5 cp or greater, about 1.5×10 5 cp or greater, or in the range of about 100 cp to about 1000 cp, about 1000 cp to about 5000 cp, about 5000 cp to about 1×10 5 cp, about 1×10 5 cp to about 1.5×10 5 cp or about 1.5×10 5 cp to about 1×10 6 cp. When the polymer material flows into the distance between the plates and the porous oxide structure, the polymer can penetrate through the layered double hydroxide and fill the voids within the oxide structure. After the polymer flows into the porous oxide, it can be allowed to harden. Thereafter, the polymer can change from a liquid state to a solid state. When the polymer becomes a solid state, it can physically attach and bond to the oxide layer.

[0047] In some examples, the polymer can include at least one of an injection-molded glass-filled PBT resin, a polyamide, and an epoxy resin. In some examples, the titanium surface can be treated by etching in a sulfuric acid solution. In some examples, the oxide layer and the polymer form a titanium-polymer bond having a bond strength of about 28 MPa or greater. Generally, any failure in the pull test includes cohesive failure in the glass-reinforced structural polymer, rather than adhesive failure between the polymer and the oxide layer or between the titanium substrate and the oxide layer that can be observed in other titanium surface treatments for generating porous titanium structures, such as micro-arc oxidation (MAO), caustic anodic oxidation, or fluoride-based anodic oxidation.

[0048] Figure 5 A graph is shown comparing the relationship of pull strength versus the type of machining of a titanium alloy (Ti6Al4V) substrate with the relationship of pull strength versus the type of machining of aluminum. In an exemplary test, metal parts from different methods were attached to a non-metal layer with a 7 mm × 7 mm surface, and the pull strength was tested individually. The non-metal layer included a glass-filled polybutylene terephthalate (PBT) surface. The different metal parts included aluminum parts and a titanium alloy (Ti6Al4V). The aluminum parts included state-of-the-art and / or industry-standard adhesion bonding pretreatments for polymer-aluminum bonding. The pretreatment can include surface etching and anodic oxidation. In the exemplary test, the aluminum parts exhibited a pull strength of about 30 MPa. The titanium alloy (Ti6Al4V) was treated with three different methods. First, in one example, the parts were anodized using a fluoride and sodium hydroxide solution. The anodized titanium parts exhibited poor pull strength. The pull strength was less than 2 MPa. In another example, the titanium alloy (Ti6Al4V) parts were immersed in sodium hydroxide (NaOH). In some embodiments, the NaOH roughened the oxide to provide a layered binary hydroxide having surface roughness and porosity. The titanium alloy (Ti6Al4V) parts exhibited a pull strength between about 18 MPa and about 25 MPa. In another example, the titanium alloy (Ti6Al4V) parts were placed in sulfuric acid for etching, as Figure 4A described in block 402, and then immersed in NaOH. The titanium alloy (Ti6Al4V) parts exhibited a pull strength between about 25 MPa and about 32 MPa, which was comparable to that of the aluminum parts and significantly stronger than previously used titanium bonding methods.

[0049] To the extent applicable to the present technology, data collected and used from various sources can be used to improve the delivery of inspiring content or any other content that a user may be interested in. The present disclosure anticipates that, in some instances, such collected data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data may include demographic data, location-based data, telephone numbers, email addresses, IDs, home addresses, data or records related to a user's health or health level (e.g., vital sign measurements, medication information, exercise information), date of birth, or any other identifying or personal information.

[0050] The present disclosure recognizes that the use of such personal information data in the technology of the present invention can be used to benefit the user. For example, the personal information data can be used to deliver target content that the user is more interested in. Therefore, the use of such personal information data enables the user to exercise planned control over the delivered content. In addition, the present disclosure also anticipates other uses of personal information data that are beneficial to the user. For example, health and fitness data can be used to provide insights into the user's overall health condition, or can be used as positive feedback for individuals using technology to pursue health goals.

[0051] The present disclosure contemplates that entities responsible for collecting, analyzing, disclosing, transmitting, storing, or otherwise using such personal information data will comply with established privacy policies and / or privacy practices. Specifically, such entities should implement and adhere to privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining the privacy and security of personal information data. Such policies should be readily accessible to users and should be updated as the data collection and / or use changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of these legitimate uses. In addition, such collection / sharing should be done after receiving the informed consent of the user. In addition, such entities should consider taking any necessary steps to safeguard and secure access to such personal information data and ensure that others with access to the personal information data comply with their privacy policies and procedures. Additionally, such entities may subject themselves to third-party assessments to demonstrate their compliance with widely accepted privacy policies and practices. Additionally, policies and practices should be adjusted to account for the specific types of personal information data being collected and / or accessed and the applicable laws and standards including the specific considerations of the jurisdiction. For example, in the United States, the collection or acquisition of certain health data may be governed by federal and / or state laws such as the Health Insurance Portability and Accountability Act (HIPAA); while health data in other countries may be subject to other regulations and policies and should be handled accordingly. Therefore, different privacy practices for different types of personal data should be maintained in each country.

[0052] Notwithstanding the foregoing, the present disclosure also contemplates embodiments in which a user selectively blocks the use or access of personal information data. That is, the present disclosure contemplates that hardware elements and / or software elements may be provided to prevent or block access to such personal information data. For example, in the case of an advertising delivery service, the inventive technology may be configured to allow a user to select "opt-in" or "opt-out" of participating in the collection of personal information data during or at any time after registering for the service. In another example, a user may choose not to provide emotion-related data for a targeted content delivery service. In another example, a user may choose to limit the length of time that emotion-related data is maintained, or to completely prohibit the development of underlying emotion states. In addition to providing "opt-in" and "opt-out" options, the present disclosure contemplates providing notifications relating to access or use of personal information. For example, a user may be notified at the time of downloading an application that their personal information data will be accessed, and then again immediately prior to the personal information data being accessed by the application.

[0053] In addition, it is an object of the present disclosure to manage and process personal information data to minimize the risk of inadvertent or unauthorized access or use. Once data is no longer needed, the risk can be minimized by limiting data collection and deleting the data. In addition, and when applicable, including in certain health-related applications, data de-identification can be used to protect the privacy of users. De-identification can be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of the data stored (e.g., collecting location data at the city level rather than at the address level), controlling how the data is stored (e.g., aggregating data across users), and / or other methods.

[0054] Thus, while the present disclosure broadly covers the use of personal information data to implement one or more of the various disclosed embodiments, the present disclosure also contemplates that the various embodiments may also be implemented without access to such personal information data. That is, the various embodiments of the inventive technology will not fail to operate properly due to the lack of all or a portion of such personal information data. For example, preferences may be inferred by relying on non-personal information data or an absolute minimum amount of personal information such as the content requested by a device associated with the user, other non-personal information available to the content delivery service, or publicly available information, and content may be selected and delivered to the user accordingly.

[0055] For purposes of illustration, the foregoing description uses specific names to provide a thorough understanding of the described embodiments. However, it will be apparent to one of ordinary skill in the art that no specific details are required in order to practice the described embodiments. Accordingly, the foregoing description of the specific embodiments described herein is presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in light of the above teachings.

Claims

1. An oxide layer on a titanium surface, the oxide layer comprising a layered double hydroxide, wherein: the titanium surface comprises an etched surface; and the oxide layer comprises a microstructure configured to enhance the bonding of the titanium surface to a polymer, the microstructure comprising a plurality of plates, each plate of the plurality of plates extending from the oxide layer at an angle between 30° and 70° relative to the titanium surface.

2. The oxide layer according to claim 1, wherein the titanium surface comprises a titanium alloy.

3. The oxide layer according to claim 1, wherein the oxide layer has a thickness of 30 nm to 70 nm.

4. The oxide layer according to claim 1, wherein the oxide layer has a porosity between 30% and 80%.

5. The oxide layer according to claim 1, wherein the plurality of plates comprise plates having a thickness of less than 10 nm.

6. The oxide layer according to claim 1, wherein: the plurality of plates comprise a first plate and a second plate; and the end of the first plate is spaced from the end of the second plate by a distance between 20 nm and 80 nm.

7. The oxide layer according to claim 1, wherein the oxide layer further comprises a porous structure defining pores having a diameter of 20 nm to 50 nm.

8. A titanium-polymer interface, the titanium-polymer interface comprising: an oxide layer on a titanium surface and a polymer, wherein: the titanium surface comprises an etched surface; and the oxide layer comprises: a first plate extending from the titanium surface at a first angle between 30° and 70°; a second plate extending from the titanium surface at a second angle between 30° and 70° and different from the first angle; wherein the bonding strength between the oxide layer and the polymer is 28 MPa or greater.

9. The titanium-polymer interface according to claim 8, wherein the oxide layer comprises a layered double hydroxide.

10. The titanium-polymer interface according to claim 8, wherein the polymer comprises at least one of a glass-filled PBT resin, a polyamide, and an epoxy resin.

11. The titanium-polymer interface according to claim 8, wherein the difference in height of each point on the etched surface is greater than 4 µm compared to the arithmetic mean of the etched surface.

12. The titanium-polymer interface according to claim 8, wherein the polymer comprises an injection-molded polymer.

13. The titanium-polymer interface according to claim 8, wherein the polymer has a dynamic viscosity of 100 cp to 1×10 6 cp.

14. A porous oxide layer formed on a titanium surface, the porous oxide layer comprising a layered double hydroxide, wherein the titanium surface comprises an etched surface and the porous oxide layer comprises a microstructure configured to enhance the bonding of the titanium surface to a polymer, the microstructure comprising a plurality of plates, each plate of the plurality of plates extending from the oxide layer at an angle between 30° and 70°, and wherein the plurality of plates comprise plates having a length from the surface of the oxide layer to the end of the plate of 10 nm to 100 nm.

15. The porous oxide layer according to claim 14, wherein: the plate is a first plate; The porous oxide layer includes a second plate and a third plate; and The end of the second plate is spaced from the end of the third plate by a distance between 20 nm and 80 nm.

16. The porous oxide layer according to claim 14, wherein the oxide layer has a thickness between 30 nm and 70 nm.

17. The porous oxide layer according to claim 14, wherein the oxide layer has a porosity between 30% and 80%.

18. The porous oxide layer according to claim 14, wherein the plate has a thickness of 10 nm.

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