CA3128998C - The manufacturing process of antibacterial, self-cleaning, and wear-resistant hybrid coatings on glazed ceramic substrates - Google Patents

Abstract

In this process antibacterial, self-cleaning and wear-resistant coatings are applied on glazed ceramic products to make antibacterial, self-cleaning, and wear-resistant ceramic materials, with high durability, and low cost of production for various applications such as building, decorative ceramics (floor, wall, cabinet surface, bathroom), tableware, etc.. A hybrid two-layer composite coating composed of TiN-Ag, as the first layer, and Ti02-Ag, as the second layer is applied via reactive magnetron sputtering, using Ti, and Ag targets, respectively. To this aim, oxygen, nitrogen, and argon gases are injected stepwise under controlled conditions. The process is designed in such a way that hybrid two-layer coatings with a thickness of less than 100 nm are created on glazed ceramic substrates. The first layer consists of TiN-Ag, which simultaneously renders antibacterial, and wear-resistant properties to the substrate. For the second layer, Ti02-Ag is deposited, which bestows both self-cleaning and antibacterial properties to the glazed ceramic substrate.

Description

Title: The manufacturing process of antibacterial, self-cleaning, and wear-resistant hybrid coatings on glazed ceramic substrates Field This invention provides improves wear-resistant antibacterial, and self-cleaning glazed ceramics, on which a hybrid layer of TiN-Ag/Ti02-Ag is applied.
Background of the Invention Reviewing the inventions, it is observed that in 1991, Elham Kharashadizadeh and All Baratzadehl patented an invention entitled "Antibacterial, scratch-resistant, high-strength and polished glaze" for health goods with a core/shell/shell structure. The core consisted of zinc oxide nanoparticles doped with cobalt or manganese, the shell consisted of silicon oxide nanoparticles, and the second shell consisted of aluminum oxide nanoparticles. Doping with cobalt or manganese significantly increased the antibacterial properties of zinc oxide nanoparticles. Besides, the presence of a shell of silicon oxide nanoparticles increased the photocatalytic properties of zinc oxide nanoparticles and increased the strength of the product.
However, in our invention, silver, and titanium oxide nanoparticles are used, which according to scientific reports have more antibacterial properties than zinc oxide nanoparticles, and it is claimed that in one process, the surface of the glaze became antibacterial and wear-resistant.
In 1994, Sanaz Naqibi et al.2 presented an invention entitled "Antibacterialization process of ceramics and tiles through a third firing process". In this invention, a new method was presented for antibacterializing the surface of glazed ceramic tiles in a third firing process. Titania powder was used to create antibacterial properties. In this invention, at the first, the antibacterial coating was prepared by mixing the aqueous suspension of titanium dioxide particles with a binder in a mixer. The prepared coating was then applied by spraying on the tile surface. Finally, to make the antibacterial coating permanent and to stabilize it, the tile was fired in a roller kiln at a temperature of 500-800 C. However, in our invention, without additional heat treatment, a long-lasting antibacterial, self-cleaning and wear-resistant coating is produced, while in the above invention, in addition to a chemical process to coat the coating, a third firing step was required. We also created a TiN-Ag/
TiO2-Ag double-layer hybrid coating which had stronger antibacterial properties than TiO2 alone, even in visible light.
' Islamic Republic of Iran Patent No. 13915014000302123

2 Islamic Republic of Iran Patent No. 139450140003000789 Date Recue/Date Received 2022-09-12 In 1994, Susan Rasouli3 filed an invention entitled "Making porcelain sanitary products with two layers with antibacterial properties". In this invention, a variety of porcelain sanitary products with antibacterial properties were made. A special two-layer glaze was used for this purpose. The first layer consisted of abase glaze, with a common formulation for sanitary ware, and the second layer consisted of a mixture of metal oxides such as titanium dioxide, zinc oxide, zirconium oxide, alumina, and several other additives. The second layer was prepared as a suspension with certain solid content and was applied using a spray with a certain thickness on the surface of glazed parts. After drying, the piece was fired in a special kiln for heat treatment and became a strong and transparent layer with antibacterial properties.
However, in our invention, the formation of a coating consisting of titanium dioxide after deposition did not require heat treatment and had a nanometer structure. While in the aforementioned invention, the second layer was obtained by firing micron particles. Nanoparticles with higher specific surface area offer much better antibacterial properties than microparticles.
In 1995, Oku Takashi and colleagues' patented an invention entitled "Antibacterial Mildew Proof Glaze Composition for Ceramic Products". This invention was related to a combination of antibacterial and anti-mold glaze containing silver and a glass or refractory for ceramics used in sanitary wares and tiles used in toilets and laundries, as well as in public places such as hospitals. In this invention, it was claimed that antibacterial properties were created by applying layers containing silver compounds. Nonetheless, in our invention, titanium dioxide, and silver nanoparticles are deposited on the glaze, which has a much greater antibacterial effect than individual Ag.
In 1996, Hayakawa and colleagues' patented "Method of Photocatalytically Making the Surface of Base Material Ultrahydrophilic, Base Material Having Ultrahydrophilic and Photocatalytic Surface, and Process for Producing Said Material". In this patent, a method of rendering the surface of a material superhydrophilic through coating the substrate with photocatalytic semiconductor materials like titania and upon photoexcitation with ultraviolet light has been discovered. The surfaces are rendered superhydrophilic so that contact angles with water below 200, preferably below 100, more preferably below 50, and even about 00 are achieved. The aim of super hydrophilicity in this patent was to prevent the growth of water drops on the surface of base materials like a mirror, lens, or windowpane in cold seasons and make these surfaces highly antifogging.
However, it is disclosed in this patent that the super hydrophilicity and antifogging characteristics are dependent upon

3 Islamic Republic of Iran Patent Application No. 139450140003010030 European Patent Application No. 0653161A1 Australian Patent No. 199650140B2 Date Regue/Date Received 2022-09-12 photoexcitation with ultraviolet light and these features are maintained in dark for a duration and reusing the materials needs renewing the super hydrophilicity by reexposure to ultraviolet light.
However, in our patent, a composite comprising a photocatalytic material and a noble metal renders the surfaces of ceramic articles antibacterial with no need for ultraviolet irradiation. Noble metals like Ag reduces the bandgap of photocatalysts like titanium oxide and shifts their photocatalytic activity towards the visible light spectrum. Hence, the use of the surfaces with photocatalytic materials and Ag composites as a coating does not need exposure to any additional ultraviolet sources.
In 2004, Gambarelli et al.6 filed a patent entitled "A Procedure for the Realization of Ceramic Manufactures, in Particular, Porcelain Stoneware Tiles and Trim Pieces, with Anti-Pollution and Anti-Bacterial Properties and Products Thereby Obtained". They applied a coating consisted of the Anatase phase with microchannels for good water absorption and more contact surface followed by sintering at 1200 C, creating a proper antibacterial property on porcelain stonewares.
However, in our invention, without the need for additional heat treatment, a coating containing TiO2 and silver particles, is applied to improve the mentioned property. The nanostructure of the coating contributed to this improvement.
In 2010, Ding Lime patented a method called "Method for Preparing Composite Ag-Ti Oxide Antibacterial Film by Magnetron Sputtering" which aimed to solve the problems of various methods of coating composites, enabling applying thin films of many metals and their oxides such as titanium, silver, zinc, copper, and platinum on various substrates such as glass, stainless steel, and cloth. In the present invention, TiO2-Ag composite coatings were deposited by PVD methods to create antibacterial surfaces on glass, steel, and fabric surfaces. In our invention, however, to improve the antibacterial properties of the surface, a hybrid coating comprising TiN-Ag/Ti02-Ag was deposited by the PVD method on the glazed building and decorative ceramics.
In 2011, Turner Alexander Edward8 registered a patent entitled "Drinking Vessel with Antibacterial Glaze" in which a coating of epoxy and TiO2 and Ag particles was applied (sprayed) on glazed containers and could be used at temperatures below 600 C and preferably 230-180 C. However, in our invention, the resulting coating created wear-resistant and antibacterial, and self-cleaning ceramics.
6 PCT Patent App. Pub. No. 2004/094341 Chinese Patent App. No. 101717920A
Great Britain Patent App. No. GB2484774A

Date Recue/Date Received 2023-04-11 In 2010, Rudolph Hugo Petnnichr filed a patent application for the "Method of Making Coated Article Having Antibacterial and/or Antifungal Coating and Resulting Product".
They introduced a hybrid coating of zinc oxide and zirconium oxide (Zn.Zry0z), both known to be oxides with antibacterial properties. They applied the coating to the glass by the sputtering method. According to subsequent scientific reports, the combination of titanium oxide and silver exhibits this property more effectively, under both UV and visible light. In our invention, nonetheless, TiN-Ag/Ti02-Ag double layers were applied to glazed ceramics to achieve optimal antibacterial, self-cleaning, and wear-resistant properties with high durability.
In 2013, Ming-Hsien Chao'', in an invention entitled "Production Method for Forming an Antibacterial Film on the Surface of an Object" claimed to create zirconium-silver nitride coatings and titanium-silver nitride coatings on silver metal by the sputtering method.
He introduced argon and nitrogen gases and selected zirconium or titanium as the cathode and silver as the anode. In our invention, nonetheless, the resulting coating, in addition to titanium nitride and silver, also contained titanium oxide, which had good antibacterial properties under UV rays, which shifted towards visible light when Ag was present and this coating was applied on glazed ceramics, which are used in toilets, hospitals, and other public places.
In the same year, Georges PiHoy', with an invention entitled "Substrate with Antimicrobial Properties" introduced a layer of metal oxides, carboxides, nitroxides, and nitrides with a binder that could be applied to materials without heat treatment or vacuum sputtering. In our invention, nonetheless, a specific composition without any organic material and with high durability was applied to ceramics used in toilets, kitchens, bathrooms, and public places by PVD
methods and was used without the need for additional operations.
In 2015, Wu Jiaqing12 patented "Self-Cleaning Antimicrobial Ceramic Glaze". By adding zinc oxide, an antibacterial agent, to the composition of a glaze, he claimed that this property was introduced in the glaze. Our invention, nevertheless, focused on the application of a coating containing titanium dioxide and silver, both of which provided superior antibacterial properties.
Besides, these materials were present as nanoparticles on the surface. The presence of both titanium dioxide and silver on the surface greatly improved the antibacterial properties.
9 .United States Patent App. Pub. No 20110256408A1 1 US Patent No. 8968529B2 11 US Patent App. Pub. No. 20110081542A1 12 Chinese Patent App. No. 101580342B

4 Date Regue/Date Received 2022-09-12 In 2016, Sajjad Ghasemi13 unveiled an invention entitled "Creating a multi-layer coating of titanium/titanium nitride (Ti/TiN) by high vacuum magnetron sputtering at low temperature on 7075 aluminum". In this invention, Ti/TiN multilayer coatings were deposited by slow vacuum and high vacuum magnetron sputtering on 7075 aluminum substrates. TIN monolayer films applied on metals by magnetron sputtering typically had a columnar microstructure, and when exposed to a corrosive medium, defects distributed across the layer can serve as paths for the corroding medium. This coating not only did not adhere well to the metal substrate but could also accelerate pitting corrosion as a galvanic couple. Therefore, adding an intermediate Ti layer (or embedding several Ti/TiN structures between the metal substrate and the outermost TiN layer) increased the density and improved adhesion throughout the coating. The intermediate Ti layers were applied alternately on the structure to prevent the growth of the TIN columnar structure, increasing the density and adhesion.
The corrosion resistance of the samples was evaluated using the electrochemical impedance method, the result of which showed improving the corrosion resistance of the coating samples many times compared to the uncoated samples. However, in our invention, the antibacterialization of the surface of ceramics, especially building ceramics which are daily use, was considered. By creating a composite coating of TiO2 and Ag nanoparticles on ceramic glazes, antibacterial and self-cleaning properties were introduced, while in the above invention, a coating of TIN and Ti was formed on aluminum metal to protect it against corrosion.
In 2016, Loka et al. 14 published "Multi-functional Ti02/Si/Ag(Cr)/TiN.
coatings for low-emissivity and hydrophilic applications" in which Ti02/Si/Ag(Cr)/TiN. multilayer thin films were deposited on soda-lime glass using RF and DC magnetron sputtering. The aim was to achieve a multi-functional thin-film stack with the combination of low emissivity and hydrophilicity in addition to high transparency. TiO2 with hydrophilicity was obtained after post-annealing the deposited films at 673 K. Heterojunction TiO2 and Si films with different bandgaps manifested super hydrophilicity with a water contact angle of ¨5 after the UV irradiation. However, in our patent TiO2-Ag composites were deposited on ceramic substrates and Ag is proved to shift the photocatalytic activity of TiO2 towards visible light, which enabled the ceramic articles to show antibacterial properties in visible light.
In 2020, Veit Schier15, in an invention called "Cutting Tool with a Multiple-Ply PVD Coating", introduced a process that created multi-layer coatings of various carbides, nitrides, and oxides of metal 13 Islamic Republic of Iran Patent No. 139550140003011832 C.Loka, K. Ryeol Park, K.-S. Lee, "Multi-functional Ti02/Si/Ag(Cr)/TiNõ
coatings for low-emissivity and hydrophilic applications", Journal of Applied Surface Science, Volume 363, Pages 439-444, 2016.
"US Patent App. Pub. No. 20180223436A1 Date Regue/Date Received 2022-09-12 on various metal and ceramic surfaces. The coating consisted of alternative layers; The wear-resistant layer was created by a high-pressure magnetron sputtering method and the bonding layer was created by the reactive and non-reactive cathodic arc method. In our invention, however, a wear-resistant coating with antibacterial properties was created in a single two-step operation. In other words, the coated ceramic entered the coating chamber only once and in a short time, a two-layer coating was created with two steps of applying gas.
In 2020, Ulrich Albers', in an invention entitled "Tool with Multi-Layer Arc PVD Coating", created a coating with tens of nanolayers containing different metal nitrides in different percentages to create a surface with very high hardness and abrasion resistance. In our invention, however, the main purpose was to achieve antibacterial coating by the sputtering method and to render wear resistance to this coating, titanium nitride was added.
In 2020, Hikov and colleagues17 published a paper entitled "Effect of TiN/TiO2 multilayer coatings on the properties of stainless steel for biomedical applications". In this study, DC-magnetron-sputtering was used to deposit TiN/TiO2 multilayer on stainless steel 304L
substrates and endodontic files. The samples were characterized in terms of physicochemical properties and biocompatibility.
The aim of TiN coating used in this study was its exceptional mechanical properties, corrosion resistance, and biocompatibility, while TiO2 was coated for its self-cleaning features. However antibacterial characteristics were not aimed in this article.
In 2020, a paper entitled "Photocatalytic performance of TiO2 nanotube structure based on TiN coating doped with Ag and Cu" was published by Zhao et al.". In this paper TiN, TiN-Ag, and TiN-Cu coatings were applied by multi-arc ion plating on Ti-6A1-4V substrates. Using anodization reaction at room temperature, nanotubes of TiO2 were fabricated on the coating. By optimization of the voltage of anodization reaction, the largest specific surface area of TiO2 nanotubes was obtained. Specific surface area is an important factor affecting the photocatalytic activity of coatings. In this paper additional process of anodizing was used to produce a photocatalytic coating with a high specific surface area. However, in our patent TiO2 was coated on the substrates through the same process as TiN and Ag, and to provide coatings with high specific surface area, porous glazed ceramics have been used as substrate. Sputtering is a deposition process on an atomic scale that enables the target 16 US Patent No. 10655211B2 17T. Hikov, M. Nikolova, P. Petrov, "Effect of TiN/TiO2 multilayer coatings on the properties of stainless steel for biomedical applications", Journal of Physics: Conference Series 1492 012029.
'Y. Zhao, C. Wang, J.Hu, J. Li, Y. Wang, "Photocatalytic performance of TiO2 nanotube structure based on TiN
coating doped with Ag and Cu", Journal of Ceramics International, Volume 47, Issue 5, Pages 7233-7240, 2021.

Date Regue/Date Received 2022-09-12 atoms to be deposited on the porosity of the rough surface of ceramics, as it is evidenced via field emission scanning electron microscopy observations.
Nanoparticles due to their small size, large surface-to-volume ratio, and greater contact surface with the environment, advanced chemical, and physical properties, and high antibacterial effect, when applied as a coating, can inhibit the growth of bacteria on the surface. With its photocatalytic properties, titanium dioxide is one of the most important antibacterial materials, which increases the photocatalytic activity in nanometers and thus its antibacterial properties.
In the case of ceramics, to create antibacterial properties by using antimicrobial nanoparticles, they are used in glaze compounds for sanitary wares, which has the following disadvantages:
1- The need to apply high temperatures to fire the glaze may lead to weakening or loss of antibacterial properties of nanoparticles.
2. The relatively thick glaze on the ceramic, causes the nanoparticles to sink in the glaze layers so that the outer surface of the glaze almost depletes from nanoparticles, while the bacteria grows on the outer surface of the glaze.
3-The higher consumption of antibacterial and photocatalytic materials added into the glaze increases the cost of the production process.
In our invention to solve the abovementioned problems including non-uniform distribution of nanoparticles on surfaces, poor antibacterial performance, low durability, high cost of production, and the difficulties on a large industrial scale, magnetron sputtering was used.
Therefore, in the present study, the coating was applied on the glazed ceramic surface, when it was heated, and this led to good adhesion of the coating.
In the present invention, a ceramic-metal composite double layer containing TiO2, Ag, and TIN
nanoparticles was applied to the glazed ceramic surfaces by the magnetron sputtering process. The coated glaze was proved to have antibacterial, self-cleaning, and wear-resistant properties. The process is designed in such a way that in addition to surface wear resistance and increase in the life of the coating, high antibacterial properties were bestowed to the surface.
Summary of the invention In this process, the magnetron sputtering process is used to create a nano-layer coating on ceramic surfaces. In this method, a gas or a mixture of different gases with a pressure of several millitorrs to hundreds of millitorrs is purged inside the chamber through special valves in a controlled manner. The most common gas used for the sputtering chamber is argon. The Ar ions generated by the ionization of the gas by electric discharge strike the surface of the titanium and silver targets and sputter atoms Date Recue/Date Received 2022-09-12 from the surface of the targets. These atoms deposit on the substrate, resulting in a thin layer.
Therefore, the coating process depends on the formation of a plasma and requires a minimum potential difference, controlled reduced pressure, and suitable gaseous species.
After producing the clay ceramic parts with common industrial methods and glazing and firing them, the parts are transferred to the coating. Titanium and silver with a purity of 99.9 wt% with specific proportions are used as targets and argon gas is selected as the operating gas and oxygen and nitrogen gas is selected as the reactive gases.
In the coating process on ceramics, various parameters contribute to the properties of the final product, which were extracted by extensive studies, trial and error, and the use of experimental design methods for the optimal value of each parameter. Among the effective parameters, the most effective ones include:
1. The voltage applied to the system 2. The gas pressure in the sputtering chamber 3. Ceramic-target distance 4. The inlet gases ratio

5. The pressure of each of the inlet gases

6. Depositing speed

7. The rotation speed of the ceramic holder

8. The ceramic substrate temperature

9. The weight ratio of silver to titanium in the target To achieve the final process to create ceramics with integrated antibacterial, photocatalytic, and wear-resistant properties, TiN-Ag/Ti02-Ag nano-coatings are created on glazed ceramics to increase the wear resistance of the antibacterial coatings.
Finally, a process was designed, by which two nanolayers were applied on the glazed ceramics, achieving a durable wear-resistant surface, while maintaining maximum antibacterial and photocatalytic properties.
The final process is as follows:
1) Placing the titanium and silver targets with a weight ratio of 50 to 1 as the targets and placing the ceramic as the substrate at a distance of 5 cm from the targets and create a vacuum in the vacuum chamber with a pressure of 6x104 ton.
2) Turning the substrate with a speed of 10-20 rpm for the uniformity of the coating.

Date Recue/Date Received 2022-09-12 3) For the first layer, simultaneously injecting argon as the operating gas and nitrogen as the reacting gas in a ratio of 90 to 10 with a constant total pressure of 15 (PT=PAr+Pii2) millitorr for 30 to 40 minutes into the vacuum chamber, and applying a voltage of 300-400 volts and a current of 0.1 amps, which causes the ejection of silver and titanium. Silver atoms do not react with nitrogen due to their nobility and deposit as metallic silver, while titanium atoms react with nitrogen gas and deposit as TiN on the substrate surface. At this stage, the substrate surface is covered with TiN-Ag thin film, with Ag and TiN introducing antibacterial and wear-resistant properties to the ceramic, respectively.
4) For the second layer, simultaneously injecting of argon gas as operating gas and oxygen gas as reactive gas in a ratio of 90 to 10 with a constant total pressure of 15 (PT=PAr+P02) millitorr for 30 to 40 minutes into a vacuum chamber and by applying voltage and creating an electric field, as a result of plasma conditions, which causes the ejection of silver and titanium atoms.
Silver gas deposits as metallic silver and titanium react with oxygen gas and deposits in the form of titanium oxide (TiO2) on the substrate. The second layer deposits on the ceramic as TiO2-Ag film. Ag introduces antibacterial properties and TiO2 introduces self-cleaning and antibacterial properties to the surface.
After performing the above steps, in the first layer, TiN Ag film with a thickness of less than 100 nm is formed, which simultaneously adds antibacterial, and wear-resistant properties to the ceramic, and in the second layer, TiO2-Ag film is formed with a thickness of 100 nrn, which adds antibacterial properties, and self-cleaning to the ceramics.
Brief Description of the Drawings In the drawings, which form part of this specification:
Fig. 1 shows an x-ray powder diffraction (XRD) pattern of ceramic with TiN-Ag/TiO2-Ag hybrid coating;
Fig. 2 shows results of grazing incidence x-ray diffraction (GDCRD) of glazed ceramics with TiN-Ag monolayer coating and TiN-Ag/TiO2-Ag hybrid coating;
Fig. 3A shows a Field Emission Scanning Electron Microscope (FESEM) image of a glazed ceramic surface;
Fig. 3B shows a FESEM image of glazed ceramic cross-section;
Fig. 3C shows a FESEM image of A and B areas for elemental analysis of the cross-section of the glazed ceramic;
Figs. 4A-4F show scanning electron microscope (SEM) images of the surface of glazed ceramic with TiN-Ag monolayer coating in different magnifications;
Fig. 5 shows elemental mapping of the surface of the ceramic with TiN-Ag monolayer coating;
Figs. 6A-6D show SEM images of the cross-section of ceramic with TiN-Ag monolayer coating;

Date Recue/Date Received 2022-09-12 Fig. 7 shows line scanning of the cross-section of ceramic with TiN-Ag monolayer coating;
Fig. 8 shows elemental mapping of the cross-section of ceramic with TiN-Ag monolayer coating;
Fig. 9A-9F show SEM images of the surface of glazed ceramic with TiN-Ag/Ti02-Ag hybrid coating in different magnifications;
Fig. 10 shows elemental mapping of the surface of the ceramic with TiN-Ag/Ti02-Ag hybrid coating;
Figs. 11A-11E show SEM images of the cross-section of ceramic with TiN-Ag/Ti02-Ag hybrid coating;
Fig. 12 shows line scanning of the cross-section of ceramic with TiN-Ag/Ti02-Ag hybrid coating;
Fig. 13 shows elemental mapping of the cross-section of ceramic with TiN-Ag/Ti02-Ag hybrid coating;
Fig. 14 shows a friction coefficient-distance diagram of the ceramic without coating;
Fig. 15 shows a friction coefficient diagram-distance of the ceramic with TiN-Ag monolayer coating;
Fig. 16 shows a friction coefficient diagram-distance of the ceramic with TiN-Ag/Ti02-Ag hybrid coaling; and Fig. 17 shows a contact angle of water droplets on ceramic with TiN-Ag/Ti02-Ag hybrid coating.
Detailed Description of the Invention Fig. 1 shows the XRD pattern of the glazed ceramic with TiN-Ag/Ti02-Ag hybrid coating. Due to the thinness of the coating, all the peaks observed are likely related to the crystalline phases of the glaze and possibly the body. The identified phases include zircon (ZrSiO4, 010710991), anorthite (CaAl2Si208, 000411486), and quartz (SiO2, 010791912).
GDCRD analysis was used to investigate the crystal structure of coatings so that only data from the surface thin layer could be obtained. Fig. 2 shows the results for the TiN-Ag monolayer coated specimens and the TiN-Ag/Ti02-Ag hybrid coated specimens. As can be seen, the peaks are related to TiN (JCPDS No. 01-087-0631), Ag (JCPDS No. 01-087-0719), and TiO2 (JCPDS
No. 01-077-0455) phases. The extra peaks that appear in the patterns are related to the substrate, which can also be seen in the normal XRD pattern of ceramic with the hybrid coating (Fig. 1).
It seems that due to the roughness (irregularities) of the ceramic glaze surface (Fig. 3A) and the partial penetration of X-rays into the substrate, these peaks are evident even in GDCRD of coated samples (albeit with a weaker intensity).
FESEM images of glazed ceramics are shown in Fig. 3. Fig. 3A, which shows the top view of the sample, demonstrates the roughness of the glazed ceramic surface. Fig. 3B, which is from the ceramic cross-section, shows that the thickness of the glaze is about 209 mm. Fig. 3C
shows the areas studied Date Recue/Date Received 2022-09-12 for elemental analysis of glaze (area A) and ceramic body (area B) by EDS. The results of EDS glaze and body are given in Table 1 and 2, respectively. The results indicate the presence of common elements in the glaze and the body.
Table 1. EDS analysis of area marked as A (glaze) in Fig. 3C
Elt Line Int Error K Kr Wt.% A% ZAF
0 Ka 132.2 13.8998 0.1985 0.1169 37.49 60.31 0.3118 Mg Ka 0.0 0.0000 0.0000 0.0000 0.00 0.00 0.5453 Al Ka 162.0 13.8998 0.0853 0.0502 7.60 7.25 0.6605 Si Ka 436.2 13.8998 0.2401 0.1414 19.23 17.62 0.7354 K Ka 11.3 0.8357 0.0108 0.0064 0.74 0.49 0.8617 Ca Ka 111.6 0.8357 0.1185 0.0697 7.74 4.97 0.9017 Zn Ka 30.0 1.4453 0.2139 0.1259 15.22 5.99 0.8274 Zr La 127.1 13.8998 0.1329 0.0783 11.98 3.38 0.6532 Total 1.0000 0.5888 100.00 100.00 Table 2. EDS analysis of area marked as B (body) in Fig. 3C
Elt Line Int Error K Kr Wt.% A% ZAF
0 Ka 174.6 3.7629 0.3309 0.1938 49.27 63.22 0.3934 Na Ka 11.6 1.2894 0.0084 0.0049 0.96 0.86 0.5120 Mg Ka 2.3 1.2894 0.0016 0.0009 0.14 0.12 0.6670 Al Ka 181.6 1.2894 0.1206 0.0707 9.30 7.08 0.7597 Si Ka 701.8 1.2894 0.4876 0.2856 36.75 26.86 0.7770 K Ka 29.7 0.4800 0.0357 0.0209 2.53 1.33 0.8253 Ca Ka 11.4 0.4800 0.0152 0.0089 1.04 0.53 0.8575 Total L0000 0.5858 100.00 100.00 Fig. 4 shows the SEM images of the surface of the ceramic coating with TiN-Ag monolayer coating via the sputtering process. From Fig. 4A the overall elemental analysis was taken and the result is shown in Table 3. As can be seen, the presence of three elements N, Ti, and Ag is evident. Fig. 4B
and 4C (secondary and back-scattered electrons, respectively) show an image with a higher magnification from the surface of the monolayer coating. The bright areas observed in these two images contain a high concentration of zirconium, which is shown by elemental analysis of area A
(Table 3). Zirconium is one of the elements in the glaze that has been identified as the zircon phase in the normal XRD spectrum of ceramic (Fig. 1). Point elemental analysis of the different regions of the Date Recue/Date Received 2022-09-12 surface of ceramic with TiN-Ag monolayer coating (Fig. 4B and 4D) shows that the elements Ag, Ti, and N are present in all of these regions. By further increasing the magnification, the nanostructure of the coating became obvious, which is shown in Fig. 4E and 4F. As can be seen, the size of the particles formed on the surface is about 20 nm and even less. Fig. 5 demonstrates the elemental mapping from the surface of the sample containing TiN-Ag monolayer coating, which shows the distribution of Ti, Ag, and N elements.
Table 3. EDS results of various regions of ceramic with TiN-Ag monolayer coating in Fig. 4A-C
wt.% Ag Zr Zn Ti Ca K Si Al 0 Region A 7.56 31.29 1.55 1.40 0.54 0.28 14.17 0.69 37.71 4.81 1.88 9.23 0.64 0.78 0.36 0.20 13.57 0.69 63.41 9.24 Region B 6.16 2.81 3.68 1.82 8.58 0.75 20.79

10.97 41.14 3.31 1.31 0.70 1.29 0.87 4.90 0.44 16.94 9.30 58.84 5.41 Region C 6.43 3.88 5.51 1.69 9.11 0.90 21.45 9.30 39.06 2.68 1.42 1.01 2.00 0.84 5.39 0.55 18.12 8.18 57.95 4.55 Overall 8.62 8.06 1.90 7.48 1.00 21.86 8.16 39.11 3.82 1.88 2.90 0.93 4.39 0.60 18.30 7.11 57.48 6.41 Fig. 6 shows the SEM images of the sample cross-section with TiN-Ag monolayer coating. To prepare these images, the samples were broken and their cross-section was examined.
Fig. 6A shows a cross-section image at low magnification, in which the structure of the glaze and the ceramic body is observed. To examine the coating from the cross-section, the magnification was increased in the area marked with Zoom, and its images are shown in Fig. 6B-D. The formation of the coating is best seen in Fig. 6C and 6D. The thin layer with light color is TiN-Ag coating. The mean layer thickness was estimated by SEM in this image to be 55 nm. It should be noted that the surface of the glaze is porous and this affects the measurement of thickness. From Fig. 6C the overall elemental analysis was taken and the result is shown in Table 4. As can be seen, the presence of Ti, and Ag is evident.
Table 4. EDS results of ceramic with TiN-Ag monolayer coating wt.% Ag Zr Ti Ca K Si Al Mg 'Na 0 Region A 8.03 12.81 2.09 3.75 0.00 19.18 13.19 0.00 0.00 40.94 0.00 1.82 3.44 1.07 2.29 0.00 16.73 19.18 0.00 0.00 62.68 0.00 Date Regue/Date Received 2022-09-12 Fig. 7 shows the line scanning analysis of the cross-section of the sample with a monolayer coating.
The change in the concentration of Ti, Ag, and N elements near the sample surface indicates the presence of a monolayer coating on the ceramic surface. It should be noted that the increase of the aluminum element level is related to the SEM sample holder, which is made of Al. It should also be noted that in the elemental analysis of nitrogen, an error is predictable due to its proximity to oxygen in terms of atomic number.
Fig. 8 shows the elemental analysis of the map from the cross-section of the sample with a single layer coating. Accumulation of Ti and Ag elements in a surface layer is evident.
Fig. 9 shows the SEM images of the ceramic surface with TiN-Ag/Ti02-Ag hybrid double coating.
From Fig. 9A an overall elemental analysis was prepared and the result is shown in Table 5. As can be seen, the presence of the three elements N, Ti, and Ag is still evident.
Fig. 9B shows an image with a higher magnification. Due to the greater thickness of the coating layer on the ceramic surface in (Fig. 9B), the formation of the coating in this magnification is better visible than the similar image of the sample with a single layer coating (Fig. 4B). Fig. 9B and 9C have the same magnification, but the modes are back-scattered and secondary electrons, respectively, with no considerable difference between the two different modes. Overall elemental analysis and point elemental analysis from different regions are prepared and are given in Table 5. An increase in the amounts of Ti and Ag elements is observed compared to the monolayer sample, but the amount of N is similar to the monolayer coating, which was expected due to the presence of TiO2 and Ag in the second layer.
Another observed difference with the monolayer sample is the particle size of the coating, which is larger than the monolayer coating (Fig. 9D-F). As shown in Fig. 9F, the particle size is about 100 nm or less.
Table 5. EDS results of various regions of ceramic with TiN-Ag/Ti02-Ag hybrid coating Ag Zr Zn Ti Ca K Si Al 0 Region A 28.54 7.77 1.75 5.74 4= .54 - 0= .58 12.32 5.87 27.34 5.54 7.81 2.52 0.79 3.54 3.34 0.44 12.96 6.43 50.47 11.68 Region B - 41.40 8.43 4.53 6.45 3= .19 0= .88 11.09 3.12 19.65 1.27 14.70 3.54 2.65 5.16 3= .05 0= .86 15.12 4.43 47.03 3.47 Region C 43.46 2.09 2.55 7.10 1.43 0.10 5.16 8.89 26.80 2.41 13.38 0.76 1.30 4.92 - 1= .19 0= .09 6.10 10.93 55.62 5.72 Overall 29.13 5.27 4.01 5.82 4.81 0= .49 13.28 4.65 28.83 3.71 8.05 1.72 1.83 3.62 3.57 0.37 14.10 5.14 53.71 7.89 Date Regue/Date Received 2022-09-12 Fig. 10 also shows the elemental mapping analysis of the surface of the sample with a double hybrid coating comprising TiN-Ag/Ti02-Ag. The distribution of Ti, N, and Ag elements is also observed.
Fig. 11 shows the SEM images of the cross-section of the sample with TiN-Ag/Ti02-Ag bilayer coating. Fig. 11A, which is prepared at low magnification, shows the structure of the glaze and the ceramic body. Higher magnifications revealed the coating structure shown in Fig. 11B-E. In Fig. 11E, the total thickness of the two layers was measured to be about 210 nm, and in Fig. 11C the thickness of the first and the second layers were 72 and 83 nm, respectively. As mentioned earlier, the differences in the thickness of the layer can be due to the roughness of the ceramic surface and the porous structure of the glaze. In Fig. 11E, elemental analysis was prepared from two regions A and B, each of which are related to the second and first layers, respectively, the result of which is shown in Table 6. Of course, it should be noted that in such magnifications, the elemental analysis also receives signals from neighboring regions, but in general, it can be seen that the amount of Ti and Ag elements in the second layer is more than the first layer.
Table 6. EDS results of ceramic with TiN-Ag/Ti02-Ag hybrid coating Ag Zr Ti Si Al 0 Region A 8.14 8.65 3.25 8.07 58.19 12.26 1.44 2.13 2.67 1.91 8.09 60.74 21.57 2.89 Region B 7.20 8.55 2.99 9.27 58.42 11.77 1.80 1.86 2.62 1.74 9.21 60.44 20.54 3.59 Fig. 12 shows the line scanning element analysis of the cross-sectional area of the sample with a two-layer coating. Increasing the concentration of Ti, Ag, and N elements and decreasing the glue-related elements near the sample surface indicate the presence of a coating on the ceramic surface.
Fig. 13 also shows the elemental mapping analysis of the cross-section of the sample with a two-layer coating. Higher values of Ti and Ag elements are visible in the surface layer.
The results of antibacterial testing of the samples with TiN-Ag monolayer coating and TiN-Ag/Ti02-Ag hybrid coating compared to the uncoated samples obtained according to 10900 standards are given in Table 7. The results indicate the successful performance of the samples in destroying bacteria.
Table 7. The antibacterial test results of the samples with TiN-Ag monolayer coating and TiN-Ag/Ti02-Ag hybrid coating Date Recue/Date Received 2022-09-12 Bacteria Antibacterial activity (R) TiN-Ag monolayer coating E. coli 2.69 Staphylococcus aureus 2.89 TiN-Ag/Ti02-Ag hybrid coating E. coli 2.92 Staphylococcus aureus 2.97 Pin-on-disc wear test was performed on the uncoated and TiN-Ag single-layer and TiN-Ag/Ti02-Ag hybrid coated ceramics. The friction-distance diagrams for these three samples are shown in Fig. 14, 15, and 16, respectively. In Fig. 14, which is related to the uncoated ceramics (glaze), the average coefficient of friction up to 100 meters is about 0.35. In Fig. 15, which is related to the single-layer ceramics, the coefficient of friction of the sample increased to about 0.15 up to a distance of 40 m and then to about 0.3. A low friction coefficient indicates an improvement in the wear resistance of the sample after lamination. According to some articles, the increase in the coefficient of friction after a certain time in the coated sample can be attributed to the formation of oxide phases that act as abrasive particles between two surfaces. Fig. 16 also shows the friction coefficient with a hybrid bilayer coating. The coefficient of friction of this sample was about 0.3, which is less than the uncoated sample and more than the single-layer coated sample, which again indicates the improvement of abrasion resistance after coating. The reason for the higher coefficient of wear of this sample than that of the single-layer sample is the higher coefficient of friction of TiO2 compared to TiN, which was predictable. This shows that the coated specimens have increased abrasion resistance.
The difference in the mass of the samples before and after wear is given in Table 8. As can be seen, the TiN-Ag single-layer coating showed less wear than the uncoated ceramic. In the case of the hybrid bilayer sample, an increase in mass was observed. According to the articles, this can be attributed to the oxidation of the components during the wear process. Therefore, the results of weight loss also indicate an improvement in the wear resistance of the samples after coating.
Table 8. weight difference of the uncoated and TiN-Ag monolayer coated and TiN-Ag/Ti02-Ag hybrid coated samples Ceramic with Ceramic with Uncoated TiN-Ag/Ti02-Ag TiN-Ag monolayer ceramic hybrid coating coating Mass before wear (g) 7.1586 6.9545 6.9670 Mass after wear (g) 7.1596 6.9538 6.9660 Date Regue/Date Received 2022-09-12 Mass difference (g) + 0.0010 - 0.0007 - 0.0010 Fig. 17 shows the contact angle of water droplets on ceramics with TiN-Ag/Ti02-Ag coating is 57 , which is less than 900, so the surface is hydrophilic and the water droplets spread on the ceramic surface and they will be able to remove contaminants from the surface during slipping.

Date Regue/Date Received 2022-09-12

Claims (10)

Claims What is claimed is:

1 . A process of forming a coating on a glazed ceramic substrate by magnetron sputtering, the process comprising:
placing a target into a sputtering chamber, the target comprising titanium (Ti) and silver (Ag);
placing the glazed ceramic substrate into the sputtering chamber;
applying a first layer of the coating to the glazed ceramic substrate by simultaneously purging argon (Ar) as a first operating gas and nitrogen (N2) as a first reacting gas into the sputtering chamber, applying a first voltage to the sputtering chamber and applying a first current to the sputtering chamber, the first layer of the coating comprising titanium nitride and Ag; and applying a second layer of the coating to the glazed ceramic by simultaneously purging Ar as a second operating gas and oxygen (02) as a second reacting gas into the sputtering chamber in a ratio of 90 to 10, applying a second voltage to the sputtering chamber and applying a second current to the sputtering chamber, the second layer of the coating comprising titanium dioxide (Ti02) and Ag.

2. The process of claim 1, wherein for both layers, the target comprises titanium and silver in a weight ratio of 50 to 1 and the target and the glazed ceramic substrate are separated by a distance of cm.

3. The process of claim 1, wherein applying the first layer comprises applying an initial vacuum of 6x 10-4 torr in the sputtering chamber and then purging Ar, as the first operating gas, with a pressure of 3.5x 10-3 torr, into the chamber.

4. The process of claim 1, wherein the N2 is purged into the sputtering chamber, as the first reactive gas, with a pressure of 5 xl(Y3 torr.

5. The process of claim 1, wherein the 02 is purged into the sputtering chamber, as the second reactive gas, with a pressure of 5x 10-3 ton.

Date Recue/Date Received 2023-12-06

6. The process of claim 1, wherein the first voltage is in a range of 300-400 V and the first current is 0.1 A.

7. The process of any one of claims 1 to 4, wherein the first layer provides wear-resistant and antibacterial properties to the glazed ceramic substrate.

8. The process of any one of claims 1 to 5, wherein the second layer provides self-cleaning, and antibacterial properties to the glazed ceramic substrate.

9. The process of claim 1, wherein the glazed ceramic substrate is for use on a floor, a wall, a cabinet surface, or in a bathroom, a decorative ceramic, or tableware.

10. A glazed ceramic substrate having a coating thereon, the coating formed on the glazed ceramic substrate by the process of any one of claims 1 to 9.

Date Recue/Date Received 2023-12-06