Radiation selective absorbing coating and process for obtaining the same at room temperature

Abstract

The present invention relates to materials and its thermal applications in different uses. More specifically, it relates to the use of a selective absorbing coating which is obtained at room temperature and is deposited on metal, which is additionally used for capturing solar energy or artificial light and converting it into thermal energy. The novelty of the present invention is related to its production process and its use and industrial application in meshes, fabrics, threads, fibers or metallic wires used in the textile industry for the manufacture of jackets, trousers, scarves, shirts, hats, gloves, mittens and mitts, sleeping bags, tents, to provide properties to absorb sunlight or artificial radiation and convert it into heat for heating said fibers or a body.

What is claimed is: 
     
         1 . A radiation selective absorbing coating obtained at room temperature comprising:
 a metallic substrate; and   at least one metal layer of chromium oxide;   wherein said metal layer has an optical absorption selectivity in the electromagnetic spectrum, reflective and antireflective characteristics and absorbance values between 80%-89% and reflectance between 15%-21%.   
     
     
         2 . The radiation selective absorbing coating according to  claim 1 , wherein the metal layer of chromium oxide layer is 100 nm to 300 nm. 
     
     
         3 . The radiation selective absorbing coating according to  claim 1 , wherein the optical absorption selectivity in the electromagnetic spectrum is up to 60% in the ultraviolet region, up to 73% in the visible spectrum and up to 89% in the infrared spectrum. 
     
     
         4 . A process for obtaining at room temperature a radiation selective absorbing coating of  claim 1 , comprising the steps of:
 (a) at least one cleaning stage;   (b) at least one first stage of immersion and standing in aqueous solution of a metallic substrate to be coated;   (c) at least one first rinsing stage;   (d) at least one second stage of immersion in aqueous solution; and   (e) at least one second rinsing stage,   (f) optionally, a polishing step,   
       and wherein the above steps (a)-(e) are performed between 20° C. and 40° C., and between 0% and 80% relative humidity. 
     
     
         5 . The process according to  claim 4 , wherein in the at least one cleaning stage (a), the metallic substrate to be coated is cleaned with solvents that remove dirt, dust, grease, inorganic fats, polymeric coatings, coatings different from oxides and oils. 
     
     
         6 . The process according to  claim 5 , wherein the solvent is selected from the group comprising silicates, phosphates, carbonates, sulfates, trichloroethylene, and/or optionally acetone. 
     
     
         7 . The process according to  claim 4 , wherein in the at least one first stage of immersion and standing in aqueous solution (b), the metallic substrate to be coated is immersed in an aqueous solution of hydrofluoric acid in a concentration range from 0% to 5%, plus nitric acid in a concentration of 5% to 15%. 
     
     
         8 . The process according to  claim 7 , wherein the standing in aqueous solution of a metallic substrate to be coated is for a time between 8 and 16 minutes. 
     
     
         9 . The process according to  claim 7 , wherein the metallic substrate to be coated has a minimum thickness from 0.03 mm up to thicknesses greater than 1.2 mm. 
     
     
         10 . The process according to  claim 4 , wherein the at least a first rinsing step (c) is performed with water. 
     
     
         11 . The process for according to  claim 10 , wherein the rinse water is distilled water. 
     
     
         12 . The process according to  claim 4 , wherein the at least one second stage of immersion (d), the pretreated metal substrate is immersed for 9 to 24 hours in an aqueous solution of chromic acid and sulfuric acid. 
     
     
         13 . The process according to  claim 12 , wherein the chromic acid and sulfuric acid have a concentration of 200 g/L to 300 g/L and 350 g/L to 450 g/L respectively. 
     
     
         14 . The process according to  claim 12 , wherein the pre-treated metallic substrate is immersed from 13 to 24 hours. 
     
     
         15 . The process according to  claim 12 , wherein the pre-treated metallic substrate is preferably immersed from 9.5 to 10.5 hours. 
     
     
         16 . The process according to  claim 4 , wherein the at least one second rinsing stage (e) is performed with water or with a liquid that removes impurities. 
     
     
         17 . The process according to  claim 4 , wherein a humidity is between 20-80% RH. 
     
     
         18 . A radiation selective absorbing coating obtained from the process  claim 4 . 
     
     
         19 . The radiation selective absorbing coating according to  claim 1 , wherein the coating is deposited on metallic substrates with different configurations, shape and geometry. 
     
     
         20 . The radiation selective absorbing coating according to  claim 19 , wherein the metallic substrate is selected from a metallic fiber, mesh, wire, fabric or steel wire for making interlining for coats, jackets, sweaters, hats, gloves, tents, shoes, boots. 
     
     
         21 . The radiation selective absorbing coating according to  claim 19 , wherein the configuration is tandem type to capture solar radiation and/or artificial light and convert it into heat to increase the temperature of the garment and the body. 
     
     
         22 . The radiation selective absorbing coating according to  claim 19 , wherein the shape and geometry can be smooth, rough, porous, tubular or laminar. 
     
     
         23 . The radiation selective absorbing coating according to  claim 1 , wherein the coating increases protection of jackets, trousers, scarves, shirts, hats, gloves, mittens and mitts, sleeping bags, tents, against UV with 73% additional protection for each application. 
     
     
         24 . The radiation selective absorbing coating according to  claim 1 , wherein the coating is apply to clothing, tents, shoes, or boots to capture solar radiation and/or artificial light, convert it into heat, retain the calorific energy and transmit it to the human body. 
     
     
         25 . The radiation selective absorbing coating according to  claim 24 , wherein the radiation selective absorbing coating obtained at room temperature further reflects infrared from human body. 
     
     
         26 . The radiation selective absorbing coating according to  claim 1 , wherein the coating is apply to thermosolar applications in the textile industry.