1 also evidenced no delamination (e.g., adhesive failure) upon application of a thirty Newton load during scratch testing (e.g., ISO 20502 (2005) testing standard). Table 1 lists various adhesion strength values measured upon performance of the listed tests when a roughness of the surface 34 was less than 0.1 microns and when the thickness T1 of the first coating 14 was between fifty microns and two hundred microns. As used herein, roughness may define a difference between the height of protrusions extending from a surface (e.g., surface 34) and the depth of recesses extending into the surface (e.g., surface 34).

TABLE 1

Test
Adhesion Strength

Static Tensile
24 MPa

Static Shear
31 MPa

Shear Fatigue
10 million cycles

at 25 MPa

Abrasion
19 mg

Resistance

In addition, the average microhardness (Vickers) was 687.4 HV, 675.6 HV, and 728.24 HV when measured (e.g., ISO 6507-1 (2018) testing standard) at the surface 34 of the coating (e.g., coating 14), the proximal side 16 of the substrate 12, and a depth D between the surface 34 and the proximal side 16 (e.g., at a location measured in the direction of the thickness T1), respectively, when a roughness of the surface 34 was less than 0.1 microns and when the thickness T1 of the first coating 14 was between fifty microns and two hundred microns. In some implementations, the average microhardness of the first coating 14 is (i) greater than the microhardness of various other titanium and/or cobalt-chromium alloys (e.g., Ti6A14V, CoCrMo, etc.), and (ii) less than the microhardness of a bulk ceramic.

A method 100 of manufacturing an implant (e.g., implant 10) will be described with reference to FIGS. 6-8. At step 102, the method 100 may include forming a substrate (e.g., substrate 12). In some implementations, the method 100 includes forming the substrate 12 by additive manufacturing (e.g., three-dimensional printing), forging, machining, grinding, injection molding, and/or casting at step 102 to include the protrusions 24, recesses 26, and projections 28.

At step 104, the method 100 may include roughening the proximal side 16 of the substrate 12. In some implementations, roughening the proximal side 16 of the substrate 12 at step 104 includes striking the proximal side 16 with a material (e.g., sand blasting), striking the proximal side 16 with a laser beam (e.g., laser ablation), and/or striking the proximal side 16 with a tool (e.g., etching) to produce the plurality of protrusions 20 and recesses 22.

At step 106, the method 100 may include inspecting the substrate 12. For example, the method 100 may include inspecting the protrusions 20, 24 and recesses 22, 26 to determine whether one or more various characteristics thereof are within predetermined specifications. If step 106 is “No” (e.g., characteristic(s) of the substrate 12 are not within predetermined specifications), the method may return to one of steps 102 or 104; otherwise, the method may proceed to step 108.

At step 108, the method 100 may include cleaning the proximal side 16 of the substrate 12. In some implementations, cleaning the proximal side 16 of the substrate at step 106 includes striking the proximal side 16 with a gas (e.g., air), liquid (e.g., water) or solid material (e.g., ice, salt, brush, etc.).

At step 110, the method 100 may include inspecting the substrate 12. For example, the method 100 may include inspecting the protrusions 20, 24 and recesses 22, 26 to determine whether one or more various characteristics thereof are within predetermined specifications. If step 110 is “No” (e.g., characteristic(s) of the substrate 12 are not within predetermined specifications), the method may return to one of steps 102, 104, or 108; otherwise, the method may proceed to step 112.

At step 112, the method 100 may include applying a bonding material to the proximal side 16 of the substrate 12. The bonding material may improve bond strength between the coating 14 and the substrate 12. In some implementations, the bonding material and the coating 14 are formed from the same material. In this regard, the bonding material may be formed from a powder that is melted and applied to the substrate 12 by increasing the enthalpy of the process during such application. For example, by altering a flow rate of a gas mixture (e.g., gas 80) and changing a total power applied to the gas mixture by, for example, a current supply (e.g., direct current supply 84), a thin layer of bonding material may be applied to the substrate 12. Alternatively, the bonding material may be applied to the substrate by using a smaller powder particle size relative to a powder particle size used for coating 14. In this scenario, the bonding material and the coating 14 may be applied to the substrate using the same process parameters described below relative to the coating 14; however, the smaller particles of the bonding material may melt and create a thin, dense bonding materials layer having superior bond strength.

At step 112, the method 100 may include applying a coating (e.g., coating 14) to the substrate 12. In some implementations, step 112 includes applying the first coating 14 to the proximal side 16 of the substrate 12 using a thermal plasma spray process (e.g., atmospheric plasma spray or vacuum plasma spray). For example, with reference to FIG. 8, at step 112, the method 100 may include creating a plasma gas 80. In particular, the method 100 may include mixing gases to form the plasma gas 80. In some implementations, the plasma gas 80 is formed from argon gas, nitrogen gas, and/or helium gas.

At step 112, the method may also include igniting the plasma gas 80. For example, electrodes 82 may be utilized to ignite the plasma gas 80. In particular, the method 100 may include passing an electrical current, produced by a direct current supply 84, through the electrodes 82 to initiate a direct current arc discharge and ionize a gas mixture to create the plasma gas 80. At step 112, the method 100 may further include melting a feedstock 86 (e.g., a powered mixture of titanium dioxide and aluminum oxide) to form a coating material 88. For example, the heated plasma gas 80 may be utilized to melt the feedstock 86 and form the coating material 88. In some implementations, every particle of the powdered feedstock 86 comprises 80% titanium dioxide and 20% aluminum oxide. In some implementations, an average size of each particle of the powdered feedstock 86 is forty-five microns.

At step 112, the method 100 may further include depositing particles of the melted feedstock (e.g., coating material 88) on the proximal side 16 of the substrate 12. For example, the method 100 may include ejecting the coating material 88 from a spray gun 90 onto the roughened proximal side 16 of the substrate 12 to form the first coating 14. In some implementations, the spray gun 90 is mounted on a robotic arm (not shown) of a plasma vapor deposition system to provide better control over the deposition step (e.g., step 112).

In some implementations, step 112 includes forming multiple layers of the coating material 88 onto the proximal side 16 of the substrate 12 to obtain a predetermined thickness (e.g., thickness T1) of the first coating 14. In particular, step 112 may be repeated one or more times (e.g., between two times and ten times) to obtain a thickness T1 between fifty microns and three hundred microns. In some implementations, the coating material 88 is deposited at step 112 for a length of time and/or a number of layers until the porosity of the first coating 14 (e.g., the porosity defined by the interstitial voids 42) is greater than 0.1%. In some implementations, the first coating 14 defines a porosity greater than 1%. In some implementations, the coating material 88 is deposited at step 112 for a length of time and/or a number of layers until the porosity of the first coating 14 is greater than 1.8%. In some implementations, the coating material 88 is deposited at step 112 for a length of time and/or a number of layers until the porosity of the first coating 14 is greater 2%. In some implementations, the coating material 88 is deposited at step 112 for a length of time and/or a number of layers until the porosity of the first coating 14 is between 2% and 5%. In some implementations, the coating material 88 is deposited at step 112 for a length of time and/or a number of layers until the porosity of the first coating 14 is between 2% and 3%.

At step 114, the method 100 may include inspecting the substrate 12 and/or coating 14. For example, the method 100 may include inspecting the first coating 14 to determine whether one or more various characteristics (e.g., thickness T1, porosity, roughness, etc.) thereof are within predetermined specifications. If step 114 is “No” (e.g., characteristic(s) of the first coating 14 are not within predetermined specifications), the method may return to one of steps 102, 104, 108, or 112; otherwise, the method may proceed to step 116.

At step 116, the method 100 may including polishing (e.g., smoothing) the outer surface 34 of the first coating 14. For example, the method may include applying and/or striking the outer surface 34 of the first coating 14 with a mechanized belt, liquid, solid, laser, CNC machine, and/or other tool to polish and smooth the outer surface 34. In some implementations, the outer surface 34 of the first coating 14 is polished at step 116 until the surface roughness is between 0.02 microns and ten microns. In some implementations, the method may include polishing the outer surface 34 until the surface roughness is less than 0.1 microns. In some implementations, the method may include polishing the outer surface 34 until the surface roughness is between 0.02 microns and 0.06 microns and/or the thickness T1 is between fifty microns and two hundred microns.

At step 118, the method 100 may include inspecting the substrate 12 and/or coating 14. For example, the method 100 may include inspecting the first coating 14 to determine whether one or more various characteristics (e.g., thickness T1, porosity, roughness, etc.) thereof are within predetermined specifications. If step 118 is “No” (e.g., characteristic(s) of the first coating 14 are not within predetermined specifications), the method may return to one of steps 102, 104, 108, 112, or 116; otherwise, the method may proceed to step 120.

At step 120, the method 100 may include cleaning the first coating 14. For example, the surface 34 of the first coating 14 may be cleaned with a solid, liquid, or gas at step 120.

At step 122, the method 100 may include inspecting the substrate 12 and/or coating 14. For example, the method 100 may include inspecting the first coating 14 to determine whether one or more various characteristics (e.g., thickness T1, porosity, roughness, etc.) thereof are within predetermined specifications. If step 122 is “No” (e.g., characteristic(s) of the first coating 14 are not within predetermined specifications), the method may return to one of steps 102, 104, 108, 112, 116, or 120; otherwise, the method may proceed to step 122 where the method may include shipping the implant 10 to a customer or other destination.

The following Clauses provide an exemplary configuration for in implant and related methods, as described above.

- Clause 1: An implant comprising: a substrate including a first outer surface; and a coating disposed on the first outer surface, the coating including eighty percent titanium dioxide and twenty percent aluminum oxide.
- Clause 2: The implant of clause 1, wherein the coating defines a thickness between fifty microns and two hundred microns relative to the first outer surface.
- Clause 3: The implant of any of clauses 1 through 2, wherein the coating includes a plurality of interstitial voids defining a porosity between two percent and ten percent.
- Clause 4: The implant of any of clauses 1 through 3, wherein the first outer surface includes a plurality of protrusions.
- Clause 5: The implant of clause 4, wherein a height of the protrusions is between two microns and ten microns.
- Clause 6: The implant of any of clauses 1 through 5, wherein the coating includes a second outer surface defining a first roughness less than 0.1 microns.
- Clause 7: The implant of clause 6, wherein the second outer surface defines a second roughness greater than 0.1 microns.
- Clause 8: The implant of clause 7, wherein the substrate includes a distal side defining a third roughness greater than the second roughness.
- Clause 9: The implant of any of clauses 1 through 7, wherein the coating includes a lamellar pattern.