METHOD FOR THE MANUFACTURE OF CERAMIC COATINGS ON THERMOPLASTIC POLYMERS BY PLASMA THERMAL PROJECTION (APS).

Abstract

The present invention relates to a method for manufacturing ceramic coatings on a thermoplastic polymer substrate by atmospheric plasma thermal spraying. Specifically, it relates to the manufacture of a multilayer coating consisting of layers of titania, hydroxyapatite, and bioactive glass. The method establishes the steps for controlling the heating / cooling rates of the polymer substrate during the application of the ceramic coatings, in order to preserve the integrity of the substrate and ensure good adhesion between it and the applied coating layers. Using this methodology, it will be possible to manufacture biocompatible ceramic coatings on PEEK for use in the fabrication of implants in various applications, such as columns, jaws, or dental implants.To control the heating / cooling conditions, a sample holder was constructed that includes a substrate cooling system manufactured using additive manufacturing and a control device based on the use of commercially available thermocouples and industrial controls. The sample holder, and its component systems, are used to position the PEEK substrates and apply the ceramic coatings via atmospheric plasma under controlled conditions.

Description

METHOD FOR THE MANUFACTURE OF CERAMIC COATINGS ON THERMOPLASTIC POLYMERS BY PLASMA THERMAL PROJECTION (APS). TECHNICAL FIELD OF THE INVENTION. The present invention relates to a method for manufacturing ceramic coatings on a substrate of thermoplastic polymer material by thermal projection with atmospheric plasma. OBJECT OF THE INVENTION. The object of the present invention is the manufacture of a multilayer ceramic coating, such as a coating comprising layers of titania, hydroxyapatite, and bioactive glass, which are deposited onto a polyetheretherketone substrate known as “PEEK,” to provide the polymer with functional surface properties, such as bioactivity. The coating is integrated by atmospheric plasma thermal spraying, known as APS, whereby the ceramics are melted and deposited onto the polymer surface. Strict control of the heat transfer conditions within the thermoplastic substrate is maintained during the process. BACKGROUND. Polymeric materials are widely used in industry for a multitude of applications due to their properties, such as high chemical resistance in diverse environments and their versatility for mass production and processing. Other properties of interest include low electrical conductivity, transparency, and low thermal conductivity. In particular, thermoplastic polymers are composed of carbon chains that form linear or branched structures and are characterized by their flexibility and deformability as the temperature increases. Generally, thermoplastic polymers have melting points below 450°C, which is lower than that of other materials such as ceramics, whose melting points typically range between 800°C and 3500°C.This characteristic is highly useful in industry for processing thermoplastic polymers into various objects and parts, for example, for manufacturing implants with different shapes and applications, such as cranial, cervical, or maxillofacial implants. These implants are typically made with thermoplastic polymers like polyetheretherketone, better known as PEEK. PEEK is a polymer with a high melting point (341°C) and can operate at temperatures up to 260°C. PEEK is often used in hot water or steam environments because it maintains physical properties such as flexural and tensile strength. It is also used for its physical properties, such as flexural strength and elastic modulus, and for its chemical resistance in biomedical applications such as implants.However, when thermoplastic polymers are required for use in more aggressive environments or functional applications, improvements to their surface properties are usually sought. For example, in the case of PEEK, when used in biomedical applications, it is known to have mechanical and physical properties similar to those of bone, but it is considered a bioinert material, so its integration with bone tissue is nonexistent. For cases where bone tissue substitutes are used, it is important that these materials have mechanical properties similar to those of the material they are intended to replace. The properties of the substitute material will depend on the type of bone tissue being replaced, although the most critical properties, in general, are the elastic modulus and density.If the elastic modulus of the replacement material is lower than that of the bone tissue, the bone surrounding the implant will experience significant stress concentration, which can eventually lead to fracture. Conversely, if the replacement material has a higher elastic modulus than the surrounding bone tissue, the replacement prosthesis will bear a disproportionate mechanical load, resulting in bone resorption due to increased osteoclast activity in the areas of bone tissue subjected to lower-than-normal loads. This is one of the causes of implant failure, infection, or fracture. In the specific case of thermoplastic materials, surface modification can be considered using a method that maintains the material's mechanical properties while also providing it with bioactive properties.Materials with known bioactive properties that can be deposited on the surface of a thermoplastic polymer are ceramic materials with melting points well above the melting temperatures of thermoplastics, such as the hydroxyapatite ceramic coating, which has a melting temperature of 1570°C, as well as titanium oxide and bioactive glasses which, when in contact with body fluids, interact ionically, promoting the formation of an apatite layer, whose structure is similar to that of human bone and is usually the precursor for surface mineralization and its integration into the bone tissue surrounding the implant. The combination of a thermoplastic material with a ceramic, therefore, can not only open up possibilities for biomedical applications but can also drive new product designs in industry, such as wear-resistant polymer parts that can withstand intermediate temperatures between 200°C and 500°C and possess high hardness. In previous decades, methods and techniques for the surface modification of polymeric materials with ceramic materials have been explored. These methods include the preparation of ceramic / polymer composites, fiber-reinforced polymers, and the manufacture of thin-film and thick-film coatings, particularly by physical vapor deposition and thermal spraying. The problem with these methods is that they require processing the material to reinforce it and combine it with the ceramic material, which modifies the polymer's properties and transforms it into a composite.In particular, physical deposition methods rely on vacuum operating conditions, and the coatings are limited to thicknesses known as thin-film coatings, i.e., below 10 micrometers. This has led to the search for other methods for applying ceramic coatings to polymeric materials, particularly thermal spraying. Thermal spraying comprises a set of material processing techniques for forming thick-layer coatings, particularly those exceeding 10 micrometers in thickness, reaching up to millimeters. The principle behind thermal spraying involves applying high amounts of thermal and kinetic energy to the material to be deposited onto the surface. This causes the material to melt, deform in its molten state on the surface, and rapidly solidify through heat transfer. The successive impact of viscous particles on the surface then results in the formation of the coating.Depending on the thermal and kinetic energy conditions, there are different thermal spraying techniques, among which, for the purposes of this invention, are plasma thermal spraying, high-velocity combustion (HVOF), and cold spraying. These techniques differ because their thermal and kinetic energy sources vary. For example, in the case of plasma, temperatures above 4000°C and particle velocities below 400 m / s are achieved; for HVOF, temperatures range between 2000°C and 3000°C and particle velocities between 300 m / s and 600 m / s; and for cold spraying, temperatures range between 300°C and 1100°C and velocities between 300 m / s and 1200 m / s. For the deposition of ceramic coatings, the use of a high-temperature technique, such as plasma thermal spraying or HVOF thermal spraying, is ideal, given the high melting point. fusion of these materials.In particular, it is also important to consider that, when applying the ceramic coating to the thermoplastic material, the thermoplastic's temperature must not exceed its degradation temperature. It is known that when a thermoplastic material is subjected to temperatures above its degradation temperature, the carbon chains begin to experience chemical bond breakage and a significant loss of the material's properties. Furthermore, it is essential that the resulting ceramic coating exhibit significant adhesion to the thermoplastic surface at pressures above 15 MPa to be considered for industrial applications, despite their different chemical compositions. These aspects must be addressed when manufacturing a thermally sprayed ceramic coating on a thermoplastic material.In this regard, there are some reported works in the literature carried out by thermal projection for the manufacture of ceramic coatings on thermoplastic polymeric materials. Document WO 2011 / 004334, published on January 13, 2011, proposes a process and apparatus for manufacturing metallic coatings with high roughness and porosity on various substrates, including metallic, ceramic, and polymeric materials, by vacuum plasma thermal spraying. The methodology employed includes the use of a vacuum chamber, a cleaning process by forming an electric arc with the substrate surface, and preheating of the surface to be coated. This methodology aims to generate controlled atmospheric conditions to prevent the oxidation of metallic materials obtained as coatings on different substrates by plasma thermal spraying.The process developed in this document is ideal for the manufacture of metallic coatings on metallic and ceramic materials for different industrial uses, particularly those where it is necessary to preserve the metallic phase and achieve high adhesion strengths. The document entitled “Development of Thermal Spray Processes for Depositing Coatings on Thermoplastics” published in the Journal of Thermal Spray Technology in 2021, indicates that to make a metallic coating on a thermoplastic polymer, the temperature of the surface of the thermoplastic polymer must be controlled to obtain a coating. Document WO2006 / 074549, dated July 20, 2006, claims a methodology for obtaining hydroxyapatite-based ceramic coatings on thermoplastic polymers. This methodology includes the surface modification of the thermoplastic polymer using a technique alternative to thermal spraying, enabling the consolidation of a ceramic / polymer composite surface. The objective of this modification is to create thermal insulation that prevents the melting and degradation of the thermoplastic polymer during the deposition of the ceramic coating by thermal spraying. Document EP 3 388 544 B1, dated September 16, 2013, proposes the manufacture of coatings on composite polymer substrates by thermal spraying. This document includes the manufacture of metallic and ceramic coatings deposited onto a surface of the composite polymer material, previously coated with an anchoring layer manufactured by an alternative method such as vapor deposition techniques or similar. This methodology is designed for fiber-reinforced polymer materials and requires insulating the substrate surface with a metallic coating so that, in a subsequent step, the surface can be exposed to the thermal spraying process, thus obtaining a metallic or ceramic coating.Regarding the control of cooling conditions, they refer to the control of the temperature of the polymer composite / metal anchoring coating system within a range of 50°C to 120°C to avoid secondary chemical reactions during the coating process. The study titled “Parametric study of Al and Al₂O₃ ceramic coatings deposited by air plasma spray onto polymer substrate,” published in Applied Surface Science in 2011, indicates that the high temperatures generated during the development of ceramic coatings on composite polymers cause cracking and negatively impact coating adhesion. More recent work, such as “Surface Metallization and Ceramic Deposition on Thermoplastic-Polymer and Thermosetting-Polymer Composite Via Atmospheric Plasma Spraying,” published in Metals and Materials International in 2020, suggests that obtaining ceramic coatings on polymeric materials, particularly thermoplastic polymers, requires the prior fabrication of a metallic coating on the polymer surface, which must be produced using alternative chemical methods.To obtain the ceramic coating, it suggests cooling the substrate as essential in the thermal spraying process. TECHNICAL PROBLEM. Currently, thermoplastic materials are known for their use in various industrial and healthcare applications. In particular, thermoplastic materials like PEEK exhibit mechanical properties similar to those of bone tissue, but lack bioactive properties. In other industrial applications, thermoplastic polymers are often chosen for their processability and range of mechanical properties, such as flexural strength and fracture toughness. However, their surface properties, such as wear and abrasion resistance, are often poor. These surface limitations have restricted the use of these materials to certain applications and necessitate the use of processing techniques or modifications to their surface properties. Although coated thermoplastic polymers are currently available, they are usually metallized using various thin-film coating techniques. While these techniques are a viable option for decorative applications and those with low surface mechanical requirements, they are not typically suitable for highly specialized applications requiring multicomponent coatings or the formation of coating architectures with defined physicochemical functions. For example, medical applications such as implants require bioactive surfaces with multifunctional properties such as osteoconduction, osteoinduction, angiogenesis, and others. Achieving these properties necessitates the development of ceramic coatings with compositions strategically tailored to these functions. Due to their high melting point, ceramic coatings are typically produced using thermal spraying techniques, particularly APS (Aerosol Spraying).Currently, some ceramic coatings produced by APS on thermoplastic polymer materials are known; however, these exhibit adhesion problems with values ​​below 20 MPa and low homogeneity of the formed layer, in addition to low deposition efficiency in the APS process. This is because, during the APS process, the surface of the thermoplastic materials is affected by the high temperatures, resulting in melting and / or surface degradation. This problem means that the coatings lack the necessary mechanical properties to withstand loads, which in turn leads to delamination and fracture of the coating. As a solution to the problem of ceramic coating homogeneity and preventing thermoplastic melting, the paper “Development of Thermal Spray Processes for Depositing Coatings on Thermoplastics,” published in the Journal of Thermal Spray Technology in 2021, proposes the use of metallic anchoring coatings to thermally insulate the polymer from the aggressive thermal conditions of the APS process for depositing the ceramic layer. However, it is also important to control the surface temperature of the thermoplastic.This control is achieved through the use of air cooling systems, although the study emphasizes the importance of systematically controlling surface temperature conditions in future work, employing temperature measurement systems to determine the optimal conditions or the cooling or heating systems required for depositing ceramic coatings by APS onto thermoplastic polymers. Specifically, it suggests cooling conditions without explaining how these controlled cooling conditions can be achieved and manipulated to ensure coating uniformity and high adhesion strength. In addition to the above, other studies have been reported, such as the article titled “Bioactive Plasma Sprayed Coatings on polymer substrates suitable for orthopedic applications: A study with PEEK,” published in the IEEE Transactions on Radiation and Plasma Medical Sciences in 2018, concerning the production of ceramic coatings by APS on thermoplastic substrates without the use of metallic anchoring coatings. These studies highlight the need to employ air-cooling systems to prevent overheating of the polymer surface and thus avoid delamination or compromise of coating homogeneity. It is noted that the coatings, when viewed in cross-section, exhibit inconsistent thickness and cracking, resulting in an adhesion strength below 20 MPa.These studies do not take into account the control of the heating conditions of the surface of the thermoplastic material or the energy conditions required in the process to achieve a balance between the energy required to melt the ceramic material of the coating and the conditions to prevent melting and degradation of the thermoplastic. On the other hand, the problem with working under vacuum conditions, as some inventions propose, with a substrate preheating system and an electric arc cleaning system coupled to the process, is that in the case of substrates with a low melting point, such as thermoplastic polymers, thermal energy accumulates and the material's degradation temperature is quickly exceeded, preventing the coating from being deposited. The problem with other methodologies is that they require manufacturing a composite material that can also be thermally affected during the thermal spraying process, and mechanical properties of the material, such as the elastic modulus and flexural strength of the thermoplastic, are also modified. Similarly, the problem with some methodologies is obtaining ceramic coating layer adhesion strengths below 20 MPa, which limits their applicability in industry, where strengths greater than 20 MPa are normally required for practical use. BRIEF DESCRIPTION OF THE INVENTION. To prevent the degradation and melting of thermoplastic polymer substrates during atmospheric plasma spraying (APS) and to achieve a homogeneous thickness of ceramic coatings and coating adhesion strengths greater than 20 MPa, a methodology for manufacturing APS ceramic coatings has been developed. This methodology involves controlling the thermal energy applied to the substrate during the process. The applied thermal energy is controlled by heat exchange systems in contact with the polymer substrate. These systems contain temperature sensors that allow for the control of the heating constant and the specific heating rate of the thermoplastic within the workability range of each material. The workability range refers to the thermal energy conditions under which melting or degradation of the thermoplastic does not occur during the process.Due to the high temperatures generated in the APS thermal spraying process and the high melting temperatures of ceramic materials compared to those of thermoplastic polymers, the deposition of ceramic coatings by APS has been and continues to be a challenge within the thermal spraying industry. The use of ceramic coatings on thermoplastics is of great interest because of the mechanical, physical, and chemical properties they can impart as a surface coating; for example, bioactivity, wear resistance, abrasion resistance, thermal insulation, etc. Given the temperature sensitivity of thermoplastic polymers, it is important that any surface modification process does not significantly degrade the polymer's mechanical properties to avoid affecting its mechanical performance in service.Therefore, strict control of the coating's processing and production conditions is of vital importance to avoid significant modifications to its properties. The adhesion of the ceramic coating to the substrate is also fundamental for real-world industrial applications. For example, in the biomedical field, international standards suggest adhesion strengths greater than 15 MPa for hydroxyapatite-based ceramic coatings. In industrial applications involving contact, coatings with adhesion strengths greater than 20 MPa are sought. A coating with low adhesion strength tends to delaminate under contact stress, leaving the polymer surface exposed. In APS thermal spraying, adhesion strength can be improved in several ways, including increasing the surface area, performing surface cleaning processes, and reducing thermal stresses during the process. Therefore, controlling surface preparation and heat transfer conditions of the substrate / coating system is fundamental to achieving homogeneity in coating formation and obtaining adhesion strengths applicable to industry. Furthermore, both variables are important to prevent significant modification or degradation of the mechanical, physical, or chemical properties of the thermoplastic substrate during the application of the coating by "APS" (Aerosol Polymer Surface Treatment). This control of coating application conditions on the thermoplastic substrate must be carried out systematically, regardless of the ceramic composition and the number of coating layers, and primarily based on the properties of the thermoplastic used as a substrate, as well as the thermal energy accumulated in the system. Specifically, the following point is intended to be protected: i) The method used for the control of heat transfer during the APS thermal spraying process of ceramic materials on thermoplastic substrates resulting in single-layer, two-layer and multi-layer ceramic coatings with homogeneous thicknesses and adhesion strengths greater than 20 MPa. BRIEF DESCRIPTION OF THE FIGURES. Figure 1 Perspective view of a sample holder; Figure 2,- Left side perspective view of a sample holder in a second modality; Figure 3.- Right side perspective view of the second type of sample holder; Figure 4,- Exploded schematic view of the cross-section AA of Figure 1 of a sample holder. Figure 5.- Schematic view of the cross-section AA of Figure 1 of a sample holder, in a configuration of use; Figure 6,- Schematic view of one of the alternatives of the single-layer ceramic coating on a substrate; Figure 1- Schematic view of one of the alternatives of the two-layer ceramic coating on a substrate; Figure 8.- Schematic view of one of the alternatives of the three-layer ceramic coating on a substrate; Figure 9.- Diagram of the heating constant in relation to the specific heating rate; Figure 10,- Diagram of the normalized power in relation to the specific heating rate; Figure 11.- Schematic view of the scratch test on the coating on the substrate; Figure 12A- Shows an image of the scratch test on substrate surfaces with a single-layer coating; Figure 12B - Shows an image of the scratch test on substrate surfaces with a two-layer coating; Figure 12C.- Shows an image of the scratch test on substrate surfaces with a three-layer coating; Figure 13A,- Shows the penetration representation of an indenter on the surface of a single-layer coating; Figure 13B.- Shows the penetration representation of an indenter on the surface of a two-layer coating; Figure 13C.- Shows the penetration representation of an indenter on the surface of a three-layer coating; Figure 14. - Shows the diagram of the adhesion stresses of the coatings on the substrate; Figure 15. - Shows the graph of the elastic modulus of the coatings on the substrate; Figure 16 shows images of the formation of an apatite layer both on the substrate and on the coatings with various ceramic materials according to the present invention, at various time intervals. DETAILED DESCRIPTION. The present invention relates to a method for manufacturing a single-layer, two-layer, or multi-layer ceramic coating (300) on thermoplastic substrates (10), particularly a method in which the heat transfer from the thermoplastic substrate (10) to the surface of the ceramic coating is controlled during the thermal spraying (APS) process of depositing the ceramic material onto the thermoplastic surface. The substrate (10), shown in Figures 1 to 8 and 11 to 13C, comprises a body with a coating face (11) and a support face (12) and has a random geometry, conforming to the geometry of the fabric to be replaced. For illustrative purposes, a substrate with a circular prism geometry will be described.In the substrate (10) there is at least one axial thermocouple housing (13) which is a blind bore, extending perpendicularly from the support face (12) to the coating face (11) near one of its perimeter edges, in which an axial thermocouple (131) is housed, with a location that allows alignment with a corresponding axial thermocouple bore (116b) when the substrate (10) is housed in a substrate retainer (117).Furthermore, there is at least one transverse thermocouple housing (14), which is a blind bore extending perpendicularly to the longitudinal axis of the substrate (10), from the peripheral face radially opposite the location of the axial thermocouple housing (13), at a mid-depth of the substrate body (10). A respective transverse thermocouple (132) is housed in this housing and positioned so that it aligns with a corresponding transverse thermocouple bore (124) in the retaining cap (120) that covers the substrate (10) when assembled into the cooling body (100). Alternatively, the geometry of the substrate (10) defines this support face (12) in such a way that heat transfer is generated from the coating face (11) to maintain the temperature of the substrate (10) below the temperature at which the thermoplastic substrate (10) degrades. For the manufacture of the coating (300) commercial hydroxyapatite powders are used, including “Captal 30®, Plasma Biotal®, UK®”, for titania the type “Metco 102®, Oerlikon Metco®” and a bioactive glass composition developed for its application for the method proposed in this application. The coating (300), as shown in Figures 6 to 8, ideally comprises a first coating layer (310) formed by two titania anchor coating films (311), which enhance the adhesion of a second hydroxyapatite coating layer (320) to the PEEK; six second coating films (321) of a second material to integrate the intermediate hydroxyapatite coating layer (320); or, ideally, six third coating films (331) of a mixture of hydroxyapatite and bioactive glass, as shown in Figure 8. Each film is made by a single pass of molten ceramic material sprayed onto the surface of the thermoplastic substrate (10), as shown in Figure 8. A sample holder (100) is provided as shown in Figure 1 to Figure 5, to hold the substrate (10) in a treatment position and to cool the substrate (10) during the manufacture of the coating (300), wherein the cooling medium of the substrate (10) is one selected from refrigerants, such as thermal liquids or air, and thus prevent the substrate (10) from thermally degrading. The sample holder (100) comprises a cooling body (110) where the substrate (10) is placed to be coated and a retaining cap (120) to hold the substrate (10) in a specific position while it undergoes the coating process, as shown in Figure 5. The cooling body (110) is a hollow body, as shown in Figure 4 and Figure 5, with perimeter walls, forming a coolant chamber (111) containing a plurality of baffle elements (112) that define cooling channels (112a). A coolant port (113) is located on a first perimeter wall (110a) of the cooling body (110), to which a coolant line (114) is connected.In a second perimeter wall (110b), preferably this second perimeter wall (110b) being opposite the first perimeter wall (110a) of the cooling body (110), there is a cooling window (115) of a dimension suitable for the flow rate of the coolant medium, which has a flow rate of a coolant stream (Q) proportional to the amount of heat required to cool the support face (12) by convection when the substrate (10) is exposed to a plasma coating treatment, as in the present invention. The cooling window (115) has a smaller area than the area of ​​the substrate (10) to limit its longitudinal movement on the cooling body (110); this cooling window (115) is generated by a lip of the body (116) that projects close to an outer edge of the perimeter wall where it is located.A substrate retainer (117) is machined from a low-relief recess in the wall where the cooling window (115) is located coaxially and adjacent to the body flange (116). It is larger in area than the cooling window (115) and is designed to freely accommodate a portion of the substrate (10), thus retaining it in a position that limits transverse movement over the cooling body (110) for processing. This configuration defines a substrate seat (116a) on the face of the body flange (116), oriented towards the adjacent substrate retainer (117) on the second perimeter wall (110b).At least one axial thermocouple bracket (116b) is machined into the body flange (116), through which a corresponding axial thermocouple (131) projects into the substrate (10). This substrate bracket is housed in the substrate retainer (117) and is oriented parallel to the longitudinal axis of the cooling body (110), positioned to align coaxially with the axial thermocouple housing (13). A third perimeter wall (110c) of the cooling body (110) has an exhaust channel (118) for directing the cooling medium out of the cooling body (110). In a preferred alternative, the exhaust channel (118) is located in a longitudinal perimeter wall (110c) oriented transversely to the defined flow path for the cooling medium entering the cooling body (110). This creates turbulence inside the cooling body (110) to promote heat convection from the substrate (10).On one of the perimeter walls of the cooling body, there is an instrumentation port (119) through which the communication means of the axial thermocouple (131a) are routed. Body joining means (110d) are provided for rigidly coupling the cooling body (110) to the retaining cover (120). For illustrative purposes, these body joining means (110d) are threaded holes that accommodate locking screws (140). The retaining cap (120) comprises a plate-shaped body with a geometry corresponding to the geometry of the wall where the cooling window (115) is located, ensuring a hermetic seal of the coolant chamber (111). A substrate housing (121) is machined in low relief on the face of the retaining cap (120) facing the cooling body (110). Its geometry complements the substrate retainer (117), and its depth allows it to accommodate and retain the substrate (10) when the retaining cap (120) is coupled with the cooling body (110), as shown in Figure 5. A treatment window (122) is adjacent to the substrate housing (121), providing an open passage through the cross-section of the retaining cap (120) that exposes the coating face (11) of the substrate (10) to a plasma torch (400).A cap flange (123) is provided, creating a treatment window (122) with a smaller area than the substrate housing (121). In this configuration, the surface of the cap flange (123) facing the substrate housing (121) forms a retaining seat (123a) that seals against unwanted flow of a coolant stream (Q) by pressing the substrate (10) against the substrate seat (116a) in the cooling body (110). At least one transverse thermocouple bore (124) is provided, projecting perpendicular to the longitudinal axis of the retaining cap (120). This bore is sized to allow the passage of a corresponding transverse thermocouple (132) to the substrate (10) and its communication medium (132a), in a location that allows it to align coaxially with a respective transverse thermocouple housing (14) in the substrate (10) when the retaining cap (120) is coupled with the cooling body (110).Cap joining means (120a) are provided for rigidly attaching the retaining cap (120) to the cooling body (110). These cap joining means (120a) are complementary to the body joining means (110d). For illustrative purposes, these cap joining means (120a) are holes that align with the threaded holes in the cooling body (110), through which the locking screws (140) freely project. Measuring instruments (130) are provided, comprising an axial thermocouple (131) and a transverse thermocouple (132), a controller circuit (not illustrated), and a thermocouple amplifier (not illustrated) that allow communication with a control medium, such as a computer (not illustrated) as known in the art. The assembly of the sample holder (100) from a condition where the retaining cap (120) is decoupled from the cooling body (110), comprises the following steps: a. Install the refrigerant line (114) at the refrigerant port (113); b. placing the substrate (10) in the substrate retainer (117) so that the support face (12) is located on the substrate seat (116a) and the support face (12) is oriented towards the cooling window (115) and towards the coolant chamber (111) to be exposed to a cooling flow (Q) of a refrigerant fluid; c. align each axial thermocouple housing (13) with the respective axial thermocouple bore (116b); d. Locate each axial thermocouple (131) in the respective axial thermocouple housing (13), through the relevant axial thermocouple bore (116b); e. install axial thermocouple communication means (131a) through the instrumentation port (119); f. Place the retaining cap (120) on the cooling body (110), whereby the substrate (10) is confined in the substrate housing (121), so that each transverse thermocouple bore (124) is aligned with a respective transverse thermocouple housing (14) in the substrate (10), so that the coating face (11) is oriented towards the treatment window (122), so that it is oriented towards the plasma stream coming from the plasma torch (400); g. install a cross thermocouple (132) in each cross thermocouple housing (14), through the relevant cross thermocouple bore (124); h. install cross-thermocouple communication means (132a) through the respective cross-thermocouple port (124); i. Join the cooling body (110) to the retaining cap (120) by means of joining elements between the body joining means (110d) and the cap joining means (120a), to exert a controlled pressure on the substrate (10) between the cap flange (123) and the body flange (116). The thermocouples (131, 132) installed in the substrate (10) converge on an electronic control board (not shown), such as an Arduino® board, which collects the system temperature as an analog signal. A thermocouple signal amplifier (not shown), such as an Adafruit max31855 amplifier, digitizes the analog signal and sends it to a computer (not shown). There, the temperature, the specific heating rate (T / dt*m) (K / (s*g)), and the heating constant (Kn) of the thermoplastic part are monitored in real time. The connection between the amplifier (not shown) and the computer (not shown) is made using common elements such as USB ports. The digitized data collected by the thermocouples (131, 132) connected to the computer (not shown) converges at a human-machine interface that allows real-time monitoring of the substrate's thermal behavior. (10) made of thermoplastic polymer material. The method for generating a ceramic coating (300) on a substrate (10) of thermoplastic polymer material comprises the steps of: Place the substrate (10) in the sample holder (100) as shown in Figure 5, so that it is kept at a certain temperature that ensures a Newton heating constant, called the “heating constant (Kn)” which is determined for the polymer material for the substrate (10) that is coated with the ceramic material according to the present invention; furthermore, supply a flow of a coolant stream (Q) of a coolant medium, such as air, at a flow rate of 13.42 m3 / h (474 ​​SCFH) at a temperature of 20°C. To detect the temperature of the substrate (10) there are thermocouples (131,132) housed in the respective thermocouple housing (13,14); in an ideal alternative, each of the group of thermocouples (131,132) is embedded in the body of the substrate (10) during the manufacture of the coating (300) to identify the temperature on the coating face (11) of the substrate (10). Real-time temperature monitoring is performed using a data acquisition circuit (not shown) that retrieves information from each thermocouple (131, 132) and adapts it for transmission to a computer (not shown). There, a human-machine interface allows observation of the control variables. This enables the recording of the maximum temperature to which the thermoplastic substrate polymer (10) is exposed during the manufacturing process of the ceramic coating (300), as well as the cooling time required between the application of each layer. It is important to measure the distance (m) from the thermocouple to the coating surface (11) of the substrate (10) housed in the axial thermocouple bore (13), as shown in Figure 5, since the surface temperature calculation depends on this value. Optionally, the heating constant (Kn) of the thermoplastic substrate (10) is controlled by mounting it on a sample holder (100) manufactured using a known method, such as additive manufacturing. Heat transfer between the support face (12) of the part to be coated and the sample holder (100) is promoted by convection, using a coolant flow (Q) within a range of -25°C to 25°C. In-situ monitoring of the substrate temperature (10) and adjustment of the normalized power variable (kW / m) complement the procedure for obtaining the heating constant (Kn) within established ranges for the thermoplastic polymer of the substrate (10), which must be greater than 0.03 s1 for PEEK. The method for manufacturing multilayer ceramic coatings on thermoplastic polymers by plasma thermal spraying comprises the following steps: a. prepare the coating surface (11) of the substrate (10) of thermoplastic polymer material with a surface texturing by mechanical abrasion, such as shot blasting or laser texturing or sandblasting also known as “sand-blasting; b. cleaning the coating surface (11) by procedures such as solvent application or ultrasonic cleaning, wherein the solvents are selected from substances such as ethanol; c. fix the substrate (10) in the sample holder (100): d. installation of thermocouples (131,132) in the thermocouple housings (13,14) of the substrate (10); e. provide a refrigerant flow (Q) of a refrigerant fluid from the refrigerant line (114), to the refrigerant chamber (111) so that it contacts the support face (12) of the substrate (10) for heat energy exchange; f. define the thermal projection parameters required for the fusion of the ceramic material, such as the plasma power (kW) from a current “A” and a voltage “V” determined for the plasma, depending on the ceramic material in its powdered solid phase, which is desired for the coating layer (310,320,330) that is to be applied to integrate the coating (330); g. determine the volume of the plasma gas mixture, such as hydrogen and argon, based on the previously determined plasma power (kW); h. define the projection distance (n) between the coating face (11) and the plasma torch outlet (400); • The calculation of the separation distance between the coating face (11) and the plasma torch (400) is initially calculated as if the coating (300) were made on a reference metal, for example, as if the coating (300) were made on a titanium (Ti) surface; i. Calculate the normalized power (kW / m), from the plasma power (kW) divided by the projection distance (n); j. Define the speed of a robotic arm (not illustrated) on which the plasma torch (400) is installed according to a defined trajectory for coating (300) on the substrate (10), based on the thickness of the layer to be generated; • The speed of the robotic arm is inversely proportional to the thickness of the deposited layer; k. Determine the flow rate of the ceramic material in its powdered solid phase in g / min for the coating (300), which is fed to the plasma torch (400), according to the desired coating film thickness (311, 321, 331) for each substrate layer (310, 320, 330); I. apply a first coating layer (310) of a first ceramic material onto the thermoplastic substrate (10); m. make the necessary adjustment in the normalized power (kW / m) by means of the projection distance (n) as a function of the specific heating rate “dT / dt*m” in (K / (s*g)) and the heating constant (Kn) for the substrate material (10) that is read at the human-machine interface, with reference to the graph in Figure 9, in order to keep it within the material processing range for the linear behavior of the normalized power (kW / m) and the heating constant (Kn) as a function of the specific heating rate (K / (s'g)), as shown in Figure 10; • To increase the heating constant (Kn), the projection distance (n) between the coating face (11) and the plasma torch outlet (400) is reduced; similarly, to decrease the heating constant (Kn), the projection distance (n) between the coating face (11) and the plasma torch outlet (400) is increased. The variation of the projection distance (n) is linear with the heating constant (Kn) because the coating conditions are controlled; n. repeat the deposition of coating material until the thickness determined for each coating layer (310,320,330) is reached with the determined ceramic material; o. make the necessary adjustments to the projection distance (n) to maintain the heating constant (Kn) at the established values; • Alternatively, the projection distance (n) is adjusted during the coating cycle to maintain the desired heating constant (Kn); p. apply a number of subsequent layers of molten material to generate the coating (300) in an equal number of materials, if the conditions determined for the coating (300) so require, for which the steps “fa” or must be replicated; • Alternatively, apply a second coating layer (320) of a second ceramic material over the first coating layer (310), for a two-layer coating; • Optionally, apply a third coating layer (330) of a third ceramic material over the second coating layer (320) for a three-layer coating; q. Perform an adjustment of the normalized power (kW / m) based on the specific heating rate (K / (s*g)) and the heating constant (Kn) of the substrate (10) that is read at the human-machine interface (not illustrated), in order that these remain within the processing range determined for the thermoplastic material of the substrate (10) in a linear behavior of the normalized power (kW / m) and the heating constant (Kn) as a function of the specific heating rate (K / (s*g)); r. remove the piece of thermoplastic polymer material coated with ceramic material from the sample holder (100). BEST WAY TO CARRY OUT THE INVENTION. Understanding that this is a thermoplastic polymer part that must be coated by the plasma thermal spraying process, to illustrate the invention, this part is placed in a sample holder (300) within reach of a robotic arm (not illustrated), which in turn has a plasma thermal spraying torch (400) installed. Based on this setup, the information is integrated to generate a ceramic coating (300) on a thermoplastic polymer substrate (10), as described. To prepare the thermoplastic polymer substrate (10), a surface texturing process is employed, such as shot peening, laser texturing, or another known surface texturing technique, to increase the roughness of the area to be coated. This process increases the surface roughness “Ra” on the coating face (11) of the thermoplastic polymer substrate (10) to values ​​between 3 and 10 micrometers. For example, the texturing of the coating face (11) is performed by shot peening with ANSI-20 alumina particles at a pressure between 2 and 6 bar. The roughness is analyzed using a profilometer to verify that a roughness value “Ra” is obtained within the range of 3 to 10 micrometers, ideally averaging 4 micrometers. To avoid residue from the texturizing process on the coating face (11) of the substrate (10), the polymer is first cleaned by immersion in ethanol, followed by immersion of the part in an ultrasonic bath using equipment specifically designed for this purpose. This final cleaning step removes grit residue embedded in the surface and any remaining particles of thermoplastic polymer generated during the surface texturizing process that could affect the adhesion strength of the coating layers (310, 320, 330). The substrate part (10) is then placed in the sample holder (100). Thermocouples (131, 132) are connected to a computerized system (not shown) that captures the temperature of the coating face (11) in real time and calculates the heating constant (Kn) of the substrate (10), following Newton's law of heating. The fabrication of each of the coating layers (310, 320, 330) of ceramic material on the surface of the coating face (11) of the thermoplastic polymer substrate (10) is carried out with a robotic “APS” type thermal projection plasma torch (400) connected to an “APS” energy control unit (not illustrated), which allows control of process parameters such as plasma power (kW), ceramic powder feed rate (g / min), thermal projection distance (n) and relative speed (m / s) of the plasma torch (400) with respect to the coating face (11) of the thermoplastic polymer substrate (10).There is a heating constant (Kn) which is a variable obtained from the temperature record by the thermocouples (131,132) and defines the heat transfer to the substrate material (10), based on the plasma power (kW) applied for the melting of the ceramic material with which the coating is formed (300), in addition to the projection distance (n) at which the plasma torch (400) is located with respect to the coating face (11) and the advance speed (m / s) of the plasma torch (400) along the operating path on the coating face (11), which is related to the plasma exposure time “APS”.Furthermore, the specific heating rate “dT / dt*m” in (K / (s*g)) is obtained from the temperature readings recorded by the thermocouples (131, 132) and the mass of the substrate material (10). This rate defines the specific heating rate (K / (s*g)) of the substrate (10) after the application of the coating films (311, 321, 331) that comprise each coating layer (310, 320, 330), respectively. By controlling the process parameters and monitoring the heating constant (Kn) and the normalized power (kW / m) as a function of the specific heating rate (K / (s*g)), the optimal conditions for obtaining a homogeneous ceramic coating (300) can be established.When the thermal spray plasma torch (400) is switched on, the plasma power (kW) / thermal spray distance (n) ratio is adjusted to maintain the heating constant (Kn) within the workability range of the substrate's thermoplastic polymer material (10). This adjustment must be made when depositing a second coating layer (320) with a different composition than the first coating layer (310), and similarly when depositing a third coating layer (339) or subsequent coating layers (310, 320, 330) with chemical compositions different from the preceding coating layers, in order to maintain the heating constant (Kn) of the thermoplastic. This procedure allows for the application of ceramic coatings (300) on thermoplastic polymers by APS with adhesion strengths that are practically applicable in industry. By way of illustration, the method of the present invention comprises the application of a multilayer ceramic coating (300), superimposed in three coating layers, wherein the first coating layer (310) consists of a first ceramic compound of Titanium Oxide (T1O2); the second coating layer (320) consists of a second ceramic compound of Hydroxyapatite (HAp, Caio (P04)β(OH)2); and the third coating layer (330) consists of a third bioactive glass compound. The coating (300) is manufactured on a substrate (10) of thermoplastic polymer material Polyetheretherketone “PEEK”, previously treated with a surface texturing to achieve a surface roughness in the range of 3 micrometers to 10 micrometers, ideally with a minimum average of 4 micrometers on the coating face (11).The resulting coating layers (310, 320, 330) comprise a first coating layer (310) of 100% titanium oxide (TiO2), a second coating layer (320) of 100% hydroxyapatite (HAp), and a third coating layer (310) of hydroxyapatite / bioactive glass (HAp / bioactive glass). The purpose of this multilayer coating (300) is to provide bioactive properties, such as osteoconduction and osteoinduction, to the coated PEEK part for biomedical applications. For these types of applications, coating adhesion strengths greater than 15 MPa must be ensured to prevent fracture or delamination of the coating under operating conditions within the human body. For the application of the first coating layer (310), second coating layer (310), and third coating layer (310) of the coating (300), a plasma power “kW” must be defined that allows the fusion of the ceramic material to be applied in the process. These conditions coincide with the power conditions calculated for use in coating ceramics on metallic and ceramic substrates. To adapt the standardized power conditions (kW / m) required for the thermoplastic polymer material that serves as the substrate (10) in the present invention, by varying the projection distance (n) of the plasma torch (400) with respect to the coating face (11) of the substrate (10) being treated, the standardized power (kW / m) is adjusted by adjusting the projection distance (n) according to the specific heating rate (K / (s'g)) and the heating constant (Kn) defined for this substrate material (10).The above occurs because if the distance between the coating face (11) and the plasma torch (400) is increased, the normalized power (kW / m) decreases and, therefore, the specific heating rate (K / (s*g)) and the heating constant (Kn) decrease; on the other hand, if the projection distance (n) between the coating face (11) and the plasma torch (400) is reduced, the normalized power increases and, consequently, the specific heating rate (K / (s'g)) and the heating constant (Kn) increase. A plasma power of 23 kW is applied to the first coating layer (310) of titanium dioxide (TiO2). A plasma power of 21 kW is applied to the second and third coating layers (320) to ensure fusion of the superimposed ceramic material layers. Plasma formation involves applying a gas mixture flow, illustratively, Argon (Ar) and Hydrogen (H), in a ratio known for the operation of the "APS" equipment, according to the ceramic material to be used as the coating (300). The powder feed rate is set according to the desired porosity for each of the coating layers (310, 320, 330) that make up the coating (300); illustratively, a powder feed rate of between 10 g / min and 45 g / min is used to generate the coating films (311, 321, 331).The number of application cycles is defined according to the deposition efficiency of the applied ceramic material. For example, two application cycles of the first molten material films are required for the first coating layer (310), and six application cycles of the second and third molten material films are required for the second (320) and third coating layers (330), which are superimposed. The time between application cycles for each of the coating films (311, 321, 331) is determined by the time it takes for the surface of the ceramic material deposit to reach ambient temperature. A coolant flow (Q) is applied before and during the thermal spraying process of the molten ceramic material. For example, an airflow is applied to the support face (12) of the substrate (10), originating from the cooling channels (112a) in the coolant chamber (111), in order to maintain the heating constant (Kn) of the thermoplastic polymer material of the substrate (10) within the desired operating range. For example, if air is used, it is supplied at a flow rate between 8.95 m³ / h (316 SFCH) and 13.42 m³ / h (474 ​​SFCH) at 20°C. The coolant flow only impacts the support face (12) of the substrate (10), and its flow is prevented from reaching the coating face (11), specifically the area of ​​the surface to be coated, since this creates turbulent flow that causes delamination of the coating (300) at the end of the ceramic material deposition process.The retaining cap (120) attached to the cooling body (110) presses in a controlled manner on the substrate (10), to form a seal with the retaining seat (123a) when the cap flange (123) presses the substrate (10) against the substrate seat (116a) in the cooling body (110). Initially, when the plasma torch (400) is switched on, a first sweep is performed under the operating conditions defined for the plasma torch (400) on the substrate (10) of the thermoplastic part without flow of ceramic material in its powdered solid phase, to make an adjustment to the projection distance (n), in such a way that the calculated normalized power (kW / m) results in a value of the specific heating rate (K / (s'g)) recorded by the thermocouples (131,132), within the range of values ​​with linear behavior as a function of the normalized power (kW / m) and in a heating constant (Kn) with values ​​within the range with linear behavior as a function of the specific heating rate (K / (s*g)); These ranges are between 0 and 0.55 K / (s*g), for the specific heating rate (K / (s*g)) and between 0 and 0.11 s1 for the heating constant (Kn) defined for PEEK as a thermoplastic polymer material for the substrate (10).Optionally, for other thermoplastic polymers, the relationship between normalized power (kW / m), specific heating rate (K / (s*g)), and heating constant (Kn) varies, as these parameters depend on the thermal diffusivity, chemical composition of the thermoplastic polymer, the applied materials, and the characteristics of the plasma beam (T). Therefore, the normalized power (kW / m) must be adjusted as previously indicated. This is because reducing the projection distance (n) increases the normalized power (kW / m), and increasing the projection distance (n) decreases the normalized power (kW / m). This procedure is also followed for the application of the second coating layer (320) and the third coating layer (330).In any of the above cases, controlling the heating constant (Kn) as a function of the specific heating rate (K / (s*g)) prevents degradation of the substrate's thermoplastic polymer (10) and enables the coating surface (11) to withstand the impact of the molten ceramic particles without causing degradation of the substrate's thermoplastic polymer (10). Once the standardized power (kW / m) for the ceramic material to be sprayed has been calculated, the ceramic material in its powdered solid phase is fed into the torch (400) to deposit the ceramic material and form the films that make up each of the layers (310, 320, 330) of the coating (300) as required. EXAMPLE OF STUDIES CARRIED OUT TO GENERATE A MULTILAYER CERAMIC COATING ON A THERMOPLASTIC POLYMER BY ATMOSPHERIC PLASMA PROJECTION. Method for generating a multilayer ceramic coating of bioactive glass / hydroxyapatite / Titania on Polyetheretherketone (PEEK) by atmospheric plasma thermal spraying (APS). The powders of the first and second ceramic materials, in this case, Titania (T1O2) and Hydroxyapatite (Caio(PO4)6(OH)2), respectively, are selected for illustrative purposes. Titania (T1O2) is a biocompatible ceramic with a coefficient of thermal expansion intermediate between that of Hydroxyapatite (Caio(PO4)6(OH)2) and Polyetheretherketone (PEEK). Hydroxyapatite (Caio(PO4)6(OH)2) and the bioactive glass are ceramics with bioactive properties; that is, they promote bone tissue generation when they come into contact with physiological fluids. The powder used to make the third coating layer contains 100% bioactive glass powder or a combination of said bioactive glass and hydroxyapatite (Caio(PO4)6(OH)2) ceramic powder, in a weight proportion greater than 0% and less than 100% of hydroxyapatite (Caio(PO4)6(OH)2) and greater than 0% and less than 100% of the bioactive glass, depending on the application of the coated part (300) made according to the present invention. The mixing of these two materials is carried out in equipment such as a ballless roller mill. The powder combination is used as filler material for manufacturing the third coating layer. The addition of bioactive glass imparts additional functional characteristics to the hydroxyapatite / titania coating, such as promoting osteoinduction, osteoconduction, and angiogenesis. Subsequently, the “APS” thermal spraying equipment is activated using the power parameters required to melt the first ceramic material and form the first coating layer (310), in this case, titanium oxide (T1O2). A standardized power of 0.17 kW / m is then established. This value is obtained by passing the plasma torch (400), mounted on an unpainted robotic arm, linearly over the polymer surface at a speed of 1 m / s. Simultaneously, the heating constant (Kn) is monitored within a range of 0 to 0.11 s1. This target range is based on the linear behavior of the heating constant in relation to the specific heating rate (K / (s*g)) of PEEK. The heating constant (Kn) is then adjusted to a value of 0.11 s1 at the end of the linear region for PEEK.The normalized power (kW / m) is established by dividing the applied power, 21 kW in this case for titanium oxide (T1O2), by the projection distance (n) between the plasma torch (400) and the coating face (11) of the substrate (10), in this case 140 mm, to maintain the heating constant (Kn) within the working range for PEEK. Subsequently, the coating (300) is manufactured using the plasma torch (400) installed on the robotic arm (not illustrated), which moves at a relative speed between the polymer surface and the plasma torch (400) of 1 m / s, where it is verified in real time that the heating constant (Kn) is maintained at a value of 0.11 s1. Next, a second coating layer (320) of ceramic material, in this case Hydroxyapatite (Caio(PO4)6(OH)2), is applied to the surface of the thermoplastic polymer previously coated with titanium dioxide (T1O2). Then, a third coating layer (330) of ceramic material, in this case Hydroxyapatite (Caio(PO4)6(OH)2) and bioactive glass, is applied, using a specified weight percentage of the powder mixture of Hydroxyapatite (Caio(PO4)6(OH)2) and bioactive glass. To obtain the second and third ceramic coating layer (320,330), a standardized power of 0.21 kW / m is applied in order to maintain the heating constant (Kn) values ​​in the range of values ​​with linear behavior as a function of the heating rate (K / s*g), in particular, heating constant (Kn) values ​​between 0 and 0.11 s-1 for PEEK. To confirm the formation of the ceramic coating after the first layer (310) of titanium oxide (T1O2), scanning electron microscopy (SEM) analysis was performed. This analysis was also carried out after the deposition of the second layer of hydroxyapatite (Caio(PO4)e(OH)2) and after the third layer of hydroxyapatite (Caio(PO4)6(OH)2) with bioactive glass, respectively. This analysis was complemented by X-ray diffraction (XRD) and electrical discharge spectroscopy (EDS). These analyses confirm the formation of the coatings, with a first layer of titanium oxide (T1O2) 85 micrometers thick, a second layer of Hydroxyapatite (Caio(P04)6(OH)2) 54 micrometers thick and a third layer of Hydroxyapatite (Caio(P04)e(OH)2) with bioactive glass 45 micrometers thick.These analyses confirm the presence of the “rutile” and “Magneli” phases in the first layer of (T1O2), of Hydroxyapatite and Calcium Phosphate in the second layer of Hydroxyapatite (Caio(PO4)6(OH)2) and of Hydroxyapatite, Calcium Phosphate, Wollastonite, and Calcium Silicate in the third layer of Hydroxyapatite (Caio(PO4)6(OH)2) with bioactive glass. SCRATCHING ADHESION TESTS. To determine the practical utility of coatings for industrial applications, in this case, the biomedical industry, the adhesion strength of ceramic coatings deposited on polyetheretherketone (PEEK) was evaluated following the methodology described above. The scratch adhesion test is performed by applying a progressive, linearly increasing, or constant load according to ASTM G171, as shown schematically in Figure 11. The linear movement is performed by a spherical indenter (30) in contact with the coating surface (300), where the critical load at which coating failure occurs is recorded in real time, as well as the normal (Fn) and tangential forces applied at all times. Failure events are recorded by an acoustic sensor (not shown).The adhesion strength of the substrate (10) / coating (300) system is determined by the normal force (Fn) recorded at the moment of failure detected by the acoustic emission sensor (unpolished) in relation to the contact area (Ac) of the spherical indenter (30) with the coating (300) at the moment of failure. The contact area (Ac) is determined by reconstructing the indentation (H) using a confocal microscope, as shown in Figures 12A to 12B. At the end of the test, scanning electron microscopy (SEM) and X-ray scattering spectroscopy (EDS) are performed to identify the characteristics of the indentation (H) obtained during the scratch test, as shown in Figures 13A to 13C.The scratch pattern reconstruction shows the surface morphology of the scratched coatings in the three coating architectures (300) evaluated. A deeper scratch pattern is identified in the two-layer and three-layer coatings, which is expected due to their greater thickness. However, the substrate surface is only reached at the end of the scratch pattern in all three cases. The results show that the coating adhesion was 50 MPa in all cases, exceeding the minimum of 15 MPa required for a ceramic coating in biomedical applications. Figure 12A shows a reconstruction of the scratch pattern of the titanium oxide monolayer coatings; Figure 12B shows a reconstruction of the scratch pattern of the hydroxyapatite-titanium oxide bilayer coatings; and Figure 12C shows a reconstruction of the scratch pattern of the hydroxyapatite-bioactive glass, hydroxyapatite, and titanium oxide trilayer coatings manufactured by APS. The EDS mappings in Figures 13A through 13C show the end of the scratch pattern, where Figure 13A corresponds to the end of the scratch pattern for the titanium oxide monolayer coating; Figure 13B corresponds to the end of the scratch pattern for the hydroxyapatite-titanium oxide bilayer coating; and Figure 13C corresponds to the end of the scratch pattern for the hydroxyapatite-bioactive glass trilayer coating. The critical load obtained in the scratch tests and the adhesion stress calculated for the 3 ceramic coating architectures obtained on PEEK are presented in Figure 14, where it can be seen that the critical load applied in “N” is greater than 100 N and the adhesion stress in “MPa” calculated based on the critical load is close to 50 MPa, higher than the 15 MPa required for the application of the thermoplastic polymer material piece of the substrate (10). TESTS TO EVALUATE THE ELASTIC MODULUS. To determine the potential mechanical effects on polyetheretherketone (PEEK) during the APS thermal spraying process, the elastic modulus of the substrate (10) was evaluated before and after the application of the multilayer coating (300). The coating consisted of titanium oxide (T1O2) in the first layer, hydroxyapatite (Caio(PO4)6(OH)2) in the second layer, and hydroxyapatite (Caio(PO4)6(OH)2) with bioactive glass in the third layer. The PEEK elastic modulus was obtained indirectly using Knoop-type indentations. The tests were divided into three groups, each tested at different distances from the surface. In the first group, the distance range was 11–35 micrometers on the coated substrate (300); in the second group, it was 90–154 micrometers on the coated substrate (300); and in the third group, samples were tested on the uncoated substrate (10). The results of these analyses are shown in the image in Figure 15.An ANOVA analysis was performed to assess whether there was a statistically significant difference between the three groups analyzed, yielding a p-value of 0.833. This indicates that the null hypothesis should be accepted, which states that there are no statistically significant differences in the elastic modulus of the thermoplastic polymer material among the three groups studied. This statistical analysis indicates that there was no modification in this mechanical property due to the fabrication of the ceramic coating layers (310, 320, 330) using the APS thermal spraying process on the PEEK material. “IN-VITRO” TESTS. In vitro tests were performed according to the ISO 23317 standard for immersion testing of the coating in simulated human plasma, specifically Hank's solution. This test involved immersing the coating / substrate system in Hank's solution at body temperature and pH, 37°C and pH 7.25, respectively. The coating was immersed for periods of 7 to 14 days in a previously sterilized container. At the end of the test, the coating surface was analyzed using scanning electron microscopy (SEM) and electrical discharge spectroscopy (EDS).The results of these analyses are shown in Figure 16, which corresponds to the surface of the substrate (10) and a bilayer coating and a trilayer coating of the coatings (300) as described, subjected to study for 0 DAYS (ZERO DAYS), 7 DAYS (SEVEN) and 14 DAYS (FOURTEEN) after immersion in Hank's solution at 37°C. The surface images show the formation of an apatite layer (340) on the surface of the bilayer coating of titanium oxide (TiO2) and hydroxyapatite (Caio(PO4)6(OH)2) and on the trilayer coating of titanium oxide (TiO2), hydroxyapatite (Caio(PO4)6(OH)2) and hydroxyapatite (Caio(PO4)6(OH)2) with bioactive glass. The formation of the apatite layer (340) is most evident at 14 days in the three-layer coating. In all cases, it is due to the interaction of the simulated human plasma-like body fluid.This layer is identified by the formation of dune-like clusters on the coating surface and the appearance of cracks due to mechanical stresses produced during the formation and growth of the apatite layer (340) on the coating surface. A close-up of the uncoated PEEK surface shows that there is no formation of the apatite layer (340). This behavior is normal for PEEK, as it is known to be an inert polymer in the body environment. It should be mentioned that there are several alternatives for depositing ceramic material on the substrate (10) to integrate the coating (300). For example, in one configuration, the substrate (10) has a single-layer coating (300), such that the material for the first coating layer (310) is selected from Titania (TiO2) or Hydroxyapatite (CaO(PO4)6(OH)2), or a mixture of Hydroxyapatite (CaO(PO4)6(OH)2) and bioactive glass, or only bioactive glass. In another alternative, there is a coating (300) with a first coating layer (310) of Titania (TiO2) and a second coating layer (320) of Hydroxyapatite (CaO(PO4)6(OH)2) superimposed on the first coating layer (310) for a two-layer coating.Alternatively, there is another option where the coating (300) is three-layered, comprising a first coating layer (310) of Titania (TiO2), a second coating layer (320) of Hydroxyapatite (Caio(PO4)6(OH)2), and a third coating layer (330) of a material selected from a mixture of Hydroxyapatite (Caio(PO4)6(OH)2) and bioactive glass. Another option for the three-layer coating (300) comprises a first coating layer (310) of Titania (TiO2), a second coating layer (320) of Hydroxyapatite (Caio(PO4)6(OH)2), and a third coating layer (330) of 100% bioactive glass. These options do not preclude the selection of various ceramic materials to integrate the coating (300) in different proportions for applications involving the thermoplastic part to be coated.Based on the selection of the ceramic material that makes up each coating layer (310, 320, 330) and the thermoplastic material for the substrate (10), the process variables must be adjusted according to the applications determined for the thermoplastic material part to be coated.

Claims

1. A method for manufacturing a ceramic coating (300) on thermoplastic substrates (10) having a coating surface (11) and a support face (12); the method of manufacturing the coating is by thermal spraying “APS”, which has the steps of: a. texturizing a coating surface (11) of the substrate (10); b. cleaning the coating surface (11); c. fixing the substrate (10) in a sample holder (100); d. installing thermocouples (131,132) on the substrate (10) in thermocouple housings (13,14); e. providing a cooling current (Q) of a cooling fluid from a cooling line (114) to a cooling chamber (111) of the sample holder (100) to contact a support face (12) of the substrate (10) for heat energy exchange; f. define the plasma power (kW) from a current “A” and a voltage “V” determined for the plasma, required for the melting of the ceramic material; g.determining the volume of the plasma gas mixture, based on the determined plasma power (kW); h. defining a projection distance (n) between the coating face (11) and the outlet of a plasma torch (400); i. placing a sample holder (300) within reach of a robotic arm (not illustrated) in which there is a plasma torch (400) for “APS” plasma thermal projection; characterized by: j. calculating the normalized power (kW / m), with the plasma power (kW) divided by the projection distance (n); j. defining the speed of a robotic arm (not illustrated) in which the plasma torch (400) is installed based on the thickness of the layer to be generated according to a defined trajectory for the coating (300) on the substrate (10); k.determine the flow rate of the ceramic material in its powdered solid phase in g / min for the coating (300) that is fed to the plasma torch (400), according to the thickness of the coating film (311, 321, 331) desired for each layer of substrate (310, 320, 330); I. turn on the robotic “APS” type thermal projection plasma torch (400); apply a first layer of coating (310) of ceramic material on the substrate (10); m. Perform the adjustment in the normalized power (kW / m) by adjusting the projection distance (n) as a function of the specific heating rate “dT / dCm in (K / (s'g)) and the heating constant (Kn) for the substrate material (10) so that it remains within the processing range of the material for the linear behavior of the normalized power (kW / m) and the heating constant (Kn) as a function of the specific heating rate (K / (s*g)); n.Repeat the deposition of coating material until the thickness determined for each coating layer (310, 320, 330) is reached with the determined ceramic material; or, make the necessary adjustments in the projection distance (n) to maintain the heating constant (Kn) at the established values.

2. The method for manufacturing a ceramic coating (300), in accordance with what is claimed in claim 1, further characterized in that the ceramic coating (300) is of the monolayer or bilayer or multilayer type on thermoplastic substrates (10).

3. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the surface texturing is carried out by methods such as mechanical abrasion surface texturing such as shot blasting or laser texturing or sandblasting; 4. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the cleaning of the coating surface (11) is carried out by applying solvents, selected from substances such as ethanol.

5. The method for manufacturing a ceramic coating (300), in accordance with what is claimed in claim 1, further characterized in that the cleaning of the coating surface (11) is carried out by procedures such as ultrasound.

6. The method for manufacturing a ceramic coating (300), in accordance with what is claimed in claim 1, further characterized in that the cooling fluid is air.

7. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the cooling fluid is air at a flow rate of 13.42 m3 / h (474 ​​SFCH) at a temperature of 20°C.

8. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the thermal spraying parameters are determined based on the ceramic material in its powdered solid phase, which is desired for the coating layer (310,320,330) to be applied and integrated into the coating (330).

9. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the volume of the plasma gas mixture comprises hydrogen and argon.

10. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the calculation of the separation distance between the coating face (11) and the plasma torch (400) is initially calculated as if the coating (300) were made on a reference metal, for example, as if the coating (300) were made on a titanium (Ti) surface; 11. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the speed of the robotic arm is inversely proportional to the thickness of the deposited layer.

12. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the specific heating rate “dT / dt*m” in (K / (s*g)) and the heating constant (Kn) for the substrate material (10) is read at a human-machine interface.

13. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that to increase the heating constant (Kn), the projection distance (n) between the coating face (11) and the plasma torch outlet (400) is reduced, and likewise to decrease the heating constant (Kn), the projection distance (n) between the coating face (11) and the plasma torch outlet (400) is increased. The variation of the projection distance (n) is linear with the heating constant (Kn) because the coating conditions are controlled.

14. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that, for the adjustment of the normalized power (kW / m), a first sweep is performed under the operating conditions defined for the plasma torch (400) on the substrate (10) of the thermoplastic part without flow of ceramic material in its powdered solid phase, to make an adjustment to the projection distance (n), such that the calculated normalized power (kW / m) results in a value of the specific heating rate (K / (s*g)) recorded by the thermocouples (131, 132), within the range of values ​​with linear behavior as a function of the normalized power (kW / m) and in a heating constant (Kn) with values ​​within the range with linear behavior as a function of the specific heating rate (K / (s*g)).

15. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized in that the adjustment of the projection distance (n) is carried out during the coating cycle to maintain the desired heating constant (Kn).

16. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized by applying a second ceramic material over the first coating layer (310) for a second coating layer (320) in a two-layer coating (300).

17. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized by applying a second coating layer (320) of a second ceramic material over the first coating layer (310) and applying a third coating layer (330) of ceramic material over the second coating layer (320) for a three-layer coating (300).

18. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized by replicating steps “fa” to apply a number of subsequent layers of molten material to generate the coating (300) in an equal number of materials, if the conditions determined for the coating (300) so require.

19. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized by adjusting the normalized power (kW / m) as a function of the specific heating rate (K / (s*g)) and the heating constant (Kn) of the substrate (10) so that these are kept within the processing range determined for the thermoplastic material of the substrate (10) in a linear behavior of the normalized power (kW / m) and the heating constant (Kn) as a function of the specific heating rate (K / (s*g)).

20. The method for manufacturing a ceramic coating (300), according to claim 1, further characterized by removing the thermoplastic polymer piece coated with ceramic material from the sample holder (100).

21. A method for manufacturing coating layers (300) to provide bioactive properties in a coated part for biomedical applications from coating films (311, 321, 331) of powdered ceramic material that is fused onto a coating face (11) of a substrate (10) of Polyetheretherketone known as “PEEK” which is a thermoplastic polymer; the substrate (10) having a coating surface (11) and a support face (12); said method is carried out by thermal spraying of molten ceramic materials with a robotic “APS” type thermal spray plasma torch (400); the method has the steps of: a. texturizing the surface to increase the surface roughness (Ra) of the coating face area (11) of the substrate (10); b. cleaning the coating surface (11); c. fixing the substrate (10) in a sample holder (100); d. install thermocouples (131,132) on the substrate (10); e.a. Place a sample holder (100) within reach of a robotic arm (not illustrated) in which the “APS” plasma thermal projection plasma torch (400) is located; b. Connect the thermocouples (131, 132) to a computerized system (not illustrated) to capture the temperature of the coating face (11) in real time; c. Provide a coolant flow (Q) from a coolant line (114) to a coolant chamber (111) of the sample holder (100) so that it contacts a support face (12) of the substrate (10) for heat energy exchange; d. Define a plasma power (kW) to melt the ceramic material to be applied; e. Determine the volume of the plasma gas mixture, based on the determined plasma power (kW); f. Define a projection distance (n) between the coating face (11) and the outlet of a plasma torch (400); method characterized by comprising: k.Calculate the normalized power (kW / m), with the plasma power (kW) divided by the projection distance (n); I. Define the speed of a robotic arm (not illustrated) on which the plasma torch (400) is installed, based on the desired layer thickness, according to a defined trajectory for the coating (300) on the substrate (10); m. Determine the flow rate of the ceramic material in its powdered solid phase in g / min for the coating (300) fed to the plasma torch (400), according to the desired coating film thickness (311, 321, 331) for each layer of substrate (310, 320, 330); n. Turn on the robotic “APS” type thermal projection plasma torch (400); o. Manufacture each of the coating layers (300) of ceramic material on the coating face (11) of the substrate (10) with the plasma torch (400); p.obtain the heating constant (Kn) following Newton's law of heating, from the temperature recorded by the thermocouples (131, 132), to define the heat transfer to the substrate material (10), based on the plasma power (kW) applied for the melting of the ceramic material with which the coating is formed (300) between a projection distance (n) at which the plasma torch (400) is located with respect to the coating face (11) and the advance speed (m / s) of the plasma torch (400) along the operating path on the coating face (11), which is related to the plasma exposure time “APS”; q. obtain the specific heating rate “dT / dt*m” in (K / (s*g)) from the temperature record by means of the thermocouples (131,132) and the mass of substrate material (10); r.s. control the plasma power (kW), the ceramic powder feed rate (g / min), the thermal projection distance (n) and the relative speed (m / s) of the plasma torch (400) with respect to the coating face (11) of the substrate (10) as process parameters and monitor the heating constant (Kn) as well as the normalized power (kW / m) as a function of the specific heating rate (K / (s*g)) of the substrate (10); t. control the process parameters and monitor the heating constant (Kn) and the normalized power (kW / m) as a function of the specific heating rate (K / (s*g)) to establish the optimal conditions for obtaining the ceramic coating (300); r. adjust the plasma power (kW) / thermal projection distance (n) ratio to maintain values ​​of the heating constant (Kn) within the workability ranges of the thermoplastic substrate (10).

22. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the robotic “APS” type thermal projection plasma torch (400) is connected to an APS power control unit (not illustrated) for controlling process parameters.

23. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the surface roughness “Ra” of the texturing on the coating face (11) of the thermoplastic polymer substrate (10) is between 3 micrometers and 10 micrometers, ideally averaging 4 micrometers.

24. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the texturing of the coating face (11) is carried out by shot blasting, laser texturing or some other surface texturing technique known in the art to increase the roughness of the area to be coated.

25. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the texturing of the coating face (11) is carried out by shot blasting with ANSI-20 alumina particles at a pressure between 2 and 6 bar.

26. The method of manufacturing coating layers (300) according to claim 21, further characterized by cleaning the coating face (11) of the substrate (10) from residues of the texturizing process by first cleaning by immersion in ethanol or by immersing the part in an ultrasonic bath.

27. The method of manufacturing coating layers (300) according to claim 21, further characterized in that after texturing, the substrate is cleaned to remove grit residues embedded in the surface and remnants of thermoplastic polymer material particles generated in the surface texturing process that may affect the adhesion strength of the coating layers (300).

28. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the process parameters are controlled by the “APS” type robotic thermal projection plasma torch (400) connected to an “APS” energy control unit (not illustrated).

29. The method of manufacturing coating layers (300) according to what is claimed in claim 21, further characterized in that the process parameters, such as the plasma power (kW), the feed rate of the ceramic powder (g / min), the thermal projection distance (n) and the relative speed (m / s) of the plasma torch (400) with respect to the coating face (11) of the substrate (10), are controlled by the robotic “APS” type thermal projection plasma torch (400).

30. The method of manufacturing coating layers (300) according to claim 21, further characterized by defining the specific heating rate (K / (s*g)) of the substrate (10) of the application of the coating films (311, 321, 331) that make up each coating layer (300) respectively.

31. The method of manufacturing coating layers (300) according to claim 21, further characterized in that adjusting the plasma power (kW) / projection distance (n) ratio to maintain heating constant (Kn) values ​​within the workability range of the thermoplastic polymer substrate (10) is to be carried out by depositing successive coating layers (300) with chemical compositions different from the preceding coating layers, in order to maintain the heating constant (Kn) values ​​of the thermoplastic.

32. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the method of the present invention comprises applying a single-layer ceramic coating (300) by depositing a coating layer (310) of a ceramic compound of Titanium Oxide (TiO2) or Hydroxyapatite (Caio(PO4)6(OH)2) or a mixture of Hydroxyapatite (Caio(PO4)6(OH)2) and bioactive glass or bioactive glass only.

33. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the method of the present invention comprises the application of a two-layer ceramic coating (300), by superimposing two coating layers (300), wherein for a first coating layer (310) there is a first ceramic compound of Titanium Oxide (T1O2) and for a second coating layer (320) there is a second ceramic compound of Hydroxyapatite (Caio(PO4)e(OH)2).

34. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the method of the present invention comprises the application of a multilayer ceramic coating (300) of the superposition of three coating layers (300), wherein for a first coating layer (310) there is a first ceramic compound of Titanium Oxide (T1O2); for a second coating layer (320) there is a second ceramic compound of Hydroxyapatite (Caio(PO4)6(OH)2); and for a third coating layer (330) there is a third compound of a mixture of Hydroxyapatite (Caio(PO4)e(OH)2) with bioactive glass.

35. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the method of the present invention comprises the application of a multilayer ceramic coating (300) of the superposition of three coating layers (300), wherein for a first coating layer (310) there is a first ceramic compound of Titanium Oxide (TiO2); for a second coating layer (320) there is a second ceramic compound of Hydroxyapatite (Ca(PO4)e(OH)2); and for a third coating layer (330) there is a third bioactive glass compound.

36. The method of manufacturing coating layers (300) according to claim 21, further characterized in that a plasma power of 23 kW is applied to a titanium dioxide (T1O2) coating layer.

37. The method of manufacturing coating layers (300) according to claim 21, further characterized in that a plasma power of 21 kW is applied to a coating layer of Hydroxyapatite (Caio (PO4)e(OH)2) to ensure the fusion of the ceramic material layers.

38. The method of manufacturing coating layers (300) according to claim 21, further characterized in that for a coating layer of a mixture of Hydroxyapatite (Caio (PCUMOH)?) and bioactive glass, a plasma power of 21 kW is applied to ensure the fusion of the ceramic material layers.

39. The method of manufacturing coating layers (300) according to claim 21, further characterized by a plasma power of 21 kW for a coating layer (330) of a bioactive glass compound.

40. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the formation of the plasma comprises the application of a flow of a mixture of Argon (Ar) and Hydrogen (H) gas, in a proportion known for the operation of the “APS” equipment, according to the ceramic material that will serve as a coating (300).

41. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the powder feed rate is set according to the desired porosity for each of the coating layers (310,320,330) that make up the coating (300).

42. The method of manufacturing coating layers (300) according to claim 21, further characterized in that a powder feed rate of between 10 g / min and 45 g / min is used to generate coating films (311,321,331).

43. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the number of application cycles is defined according to the deposition efficiency of the applied ceramic material.

44. The method of manufacturing coating layers (300) according to claim 21, further characterized in that two application cycles of first molten material films are performed for a first coating layer (310).

45. The method of manufacturing coating layers (300) according to claim 21, further characterized in that two application cycles of first molten material films are performed for the first coating layer (310) and six application cycles of second molten material films are performed for a second coating layer (320).

46. ​​The method of manufacturing coating layers (300) according to claim 21, further characterized in that two application cycles of first molten material films are performed for the first coating layer (310), six application cycles of second molten material films are performed for a second coating layer (320), and six application cycles of third molten material films are performed for a third coating layer (330).

47. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the time between application cycles of each of the coating films (311, 321, 331) is determined by the time that elapses until the surface of the ceramic material deposit layer reaches room temperature.

48. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the coolant current (Q) is an air current from cooling channels (112a) in a coolant chamber (111) of a sample holder (100), to maintain the heating constant (Kn) corresponding to the thermoplastic polymer material of the substrate (10) at the desired operating values.

49. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the coolant stream (Q) is an air stream at a flow rate of between 8.95 m3 / h (316 SFCH) and 13.42 m3 / h (474 ​​SFCH) at 20°C.

50. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the flow of the coolant stream (Q) only impacts the support face (12) of the substrate (10) and this flow is prevented from overflowing towards the coating face (11), specifically the area of ​​the surface to be coated, to avoid turbulent flow that causes delamination of the coating (300) at the end of the ceramic material deposition process.

51. The method of manufacturing coating layers (300) according to claim 21, further characterized in that a first sweep is performed under the operating conditions defined for the plasma torch (400) on the substrate (10) of the thermoplastic part without flow of ceramic material in its powdered solid phase, to adjust the projection distance (n), such that the calculated normalized power (kW / m) results in a value of the specific heating rate (K / (s*g)) recorded by the thermocouples (131, 132), within the range of values ​​with linear behavior as a function of the normalized power (kW / m) and in a heating constant (Kn) with values ​​within the range with linear behavior as a function of the specific heating rate (K / (s*g)) 52. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the ranges for the specific heating rate (K / (s*g)) are between 0 and 0.55 K / (s*g), and for the heating constant (Kn) defined for PEEK as a thermoplastic polymer material for the substrate (10) between 0 and 0.11 s1.

53. The method of manufacturing coating layers (300) according to claim 21, further characterized in that the ratio between normalized power (kW / m), specific heating rate (K / (s*g)) and heating constant (Kn) varies for each polymer, since these parameters depend on the thermal diffusivity, chemical composition of the thermoplastic polymer material, the applied materials and the characteristics of the plasma beam (T) formed.

54. A sample holder (100) for holding a substrate (10) in a treatment position and for cooling the thermoplastic substrate (10) during the manufacture of a ceramic coating (300), in which a coolant circulates; wherein the substrate (10) has a body defining a coating face (11), a support face (12), at least one axial thermocouple housing (13), and at least one transverse thermocouple housing (14); said sample holder (100) has a cooling body (110) in which the substrate (10) is placed for coating, which is a hollow body with perimeter walls and a retaining cap (120) for holding the substrate (10) in a specific position while it is subjected to the coating process with ceramic material melted by a plasma torch (400), characterized in that it comprises: - a coolant chamber (111) in the hollow body;- a coolant port (113) in a first perimeter wall (110a) of the cooling body (110) for connecting a coolant line (114); - a cooling window (115) in a second perimeter wall (110b) of the cooling body (110) of a dimension suitable for the flow rate of the coolant; - a substrate retainer (117) coaxial and adjacent to the cooling window (115), with a larger area than the window for the free seating of a portion of the substrate (10) to retain it in a position that limits transverse movement on the cooling body (110); - an exhaust channel (118) for directing the cooling medium out of the cooling body (110);- a substrate housing (121) in the retaining cap (120), on the face facing the cooling body (110), having a geometry that complements the substrate retainer (117) and a depth that allows the substrate (10) to be housed and retained when the retaining cap (120) is coupled with the cooling body (110); - a treatment window (122) adjacent to the substrate housing (121), is an open passage through the cross-section of the retaining cap (120) that allows the coating face (11) of the substrate (10) to be exposed to the plasma torch (400); - the coolant medium has a coolant flow rate (Q) proportional to the amount of heat required to convectively cool the support face (12).

55. The sample holder (100) to support a substrate (10) as claimed in claim 54, further characterized in that the substrate (10) comprises and is of a random geometry, conforming to the geometry of the tissue to be replaced.

56. The sample holder (100) for supporting a substrate (10) as claimed in claim 54, further characterized in that each axial thermocouple housing (13), which is a blind bore, extending perpendicularly from the support face (12) to the coating face (11) near one of its peripheral edges, for housing an axial thermocouple (131), with a location that allows alignment with a corresponding axial thermocouple bore (116b) when the substrate (10) is housed in a substrate retainer (117).

57. The sample holder (100) for supporting a substrate (10) as claimed in claim 54, further characterized in that each transverse thermocouple housing (14) is a blind bore, extending perpendicularly to the longitudinal axis of the substrate (10), from the peripheral face radially opposite the location of the axial thermocouple housing (13), to a mid-depth of the substrate body (10), in which a respective transverse thermocouple (132) is housed and is aligned with a corresponding transverse thermocouple bore (124) in the retaining cap (120) covering the substrate (10) when assembled into the cooling body (100).

58. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the geometry of the substrate (10) defines the support face (12) so as to generate a heat transfer from the coating face (11) to keep the temperature of the substrate (10) below the temperature that degrades the substrate (10).

59. The sample holder (100) for holding a substrate (10) in accordance with claim 54, further characterized in that the cooling medium of the substrate (10) is one selected from cooling substances, such as thermal liquids or air, to prevent the substrate (10) from thermally degrading.

60. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized by a plurality of deflector elements (112) in the coolant chamber (111) that define cooling channels (112a).

61. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the second perimeter wall (110b) where the cooling window is located is located opposite the first perimeter wall (110a) of the cooling body (110).

62. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the cooling window (115) is of a dimension suitable to the flow of the coolant stream (Q), of a smaller area than the area of ​​the substrate (10) to limit its longitudinal movement over the cooling body (110).

63. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the cooling window (115) is of a smaller area than the area of ​​the substrate (10) to limit its longitudinal movement on the cooling body (110).

64. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the cooling window (115) is generated by a body flange (116) projecting close to an outer edge of the perimeter wall where it is located.

65. The sample holder (100) to be able to hold a substrate (10) in accordance with what is claimed in claim 54, further characterized in that the substrate retainer (117) is a low relief machined into the wall where it is located, adjacent to a body flange (116).

66. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized by a substrate seat (116a) on the face of a body flange (116) facing the adjacent substrate retainer (117).

67. The sample holder (100) for supporting a substrate (10) as claimed in claim 54, further characterized by at least one axial thermocouple bore (116b) machined into the body flange (116) to project a corresponding axial thermocouple (131) into the substrate (10) housed in the substrate retainer (117), oriented parallel to the longitudinal axis of the cooling body (110) with a location enabling it to align coaxially with the axial thermocouple housing (13) in the substrate body (10).

68. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the exhaust channel (118) is located in a third longitudinal perimeter wall (110c) oriented transversely to the flow defined for the entry of the cooling medium into the cooling body (110) to form turbulence inside the cooling body (110) and promote heat convection from the substrate (10).

69. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that on one of the perimeter walls of the cooling body, there is an instrumentation port (119) through which means of communication of the axial thermocouple (131a) are conducted.

70. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that it has threaded holes in which locking screws (140) are received as means of joining the body (110d) to rigidly couple the cooling body (110) with the retaining cap (120).

71. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized in that the retaining cap (120) comprises a plate-shaped body of a geometry corresponding to the geometry of the wall where the cooling window (115) is located to ensure the airtight closure of the coolant chamber (111).

72. The sample holder (100) to be able to hold a substrate (10) in accordance with what is claimed in claim 54, further characterized in that the treatment window (122) is of a smaller area than the substrate housing (121).

73. The sample holder (100) to be able to hold a substrate (10) in accordance with what is claimed in claim 54, further characterized in that a lid flange (123) generates the treatment window (122).

74. The sample holder (100) for holding a substrate (10) in accordance with claim 54, further characterized in that a surface of the lid flange (123) facing the substrate housing (121) forms a retaining seat (123a) that serves as a seal against unwanted flow of a coolant stream (Q) by pressing the substrate (10) against a substrate seat (116a) in the cooling body (110).

75. The sample holder (100) for supporting a substrate (10) as claimed in claim 54, further characterized by at least one transverse thermocouple bore (124), projecting perpendicular to the longitudinal axis of the retaining cap (120), of a dimension allowing passage of a corresponding transverse thermocouple (132) into the substrate (10) and its transverse thermocouple communication means (132a), in a location enabling coaxial alignment with a respective transverse thermocouple housing (14) of the substrate (10), when the retaining cap (120) is coupled with the cooling body (110).

76. The sample holder (100) to be able to hold a substrate (10) in accordance with what is claimed in claim 54, further characterized by lid joining means (120a) complementary to 5 body joining means (110d) to rigidly couple the retaining lid (120) to the cooling body (110).

77. The sample holder (100) to support a substrate (10) in accordance with claim 54, further characterized by lid joining means (120a) being holes that align with threaded holes in the cooling body (110) through which locking screws (140) freely project.

78. The sample holder (100) for holding a substrate (10) in accordance with claim 54, further characterized by measuring instruments (130), comprising an axial thermocouple (131) and a transverse thermocouple (132), a controller circuit (not illustrated), and a thermocouple amplifier (not illustrated) that allow communication with a control means.