Tata Steel has filed a patent for a method of electrodeposition to create a functional or decorative chromium layer on a metallic substrate. The process uses a halide-ion free and boric acid free aqueous electrolyte solution, with specific concentrations of chromium compound, sodium or potassium sulphate, and a formate salt as a complexing agent. GlobalData’s report on Tata Steel gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData’s company profile on Tata Steel, Extraction by leaching was a key innovation area identified from patents. Tata Steel's grant share as of September 2023 was 54%. Grant share is based on the ratio of number of grants to total number of patents.
Method for electrodeposition of chromium layer onto metallic substrate
A recently filed patent (Publication Number: US20230243057A1) describes a method for electrodeposition of a functional or decorative chromium layer onto a metallic substrate. The method can be used in both batch and continuous electrodeposition processes and utilizes a halide-ion free and boric acid free aqueous electrolyte solution.
The electrolyte solution consists of a trivalent chromium compound provided by a water-soluble chromium(III) salt, with a concentration of Cr3+-ions ranging from 50 mM to 1000 mM. Additionally, the solution contains a total amount of sodium sulphate or potassium sulphate ranging from 25 mM to 2800 mM. A formate salt is used as a complexing agent to enhance the electrodeposition process.
The pH of the electrolyte solution is adjusted to a value of 2.00 or more. In the batch electrodeposition process, the pulse duration ranges from 0.5 to 2.5 seconds, with an interpulse period between 0.5 and 5 seconds. Similarly, in the continuous electrodeposition process, the pulse duration and interpulse time range from 0.5 to 2.5 seconds and 0.5 to 5 seconds, respectively. In a specific embodiment of the continuous process, the pulse duration is between 0.5 and 2 seconds, and the interpulse time is between 0.5 and 2 seconds.
The method allows for the deposition of at least 1 g/m2 of chromium onto the metallic substrate. The temperature of the electrolyte during electrodeposition is maintained at a minimum of 35°C and a maximum of 50°C. In the continuous electrodeposition process, the line speed of the electrodeposition line should be at least 50 m/min, preferably at least 100 m/min.
The metallic substrate can be an unalloyed or low-alloyed steel strip or sheet, with options for a nickel coated steel strip or sheet or a copper coated steel strip or sheet. The resulting chromium layer on the metallic substrate can have a gloss value of at least 800 when measured under an angle of 20° in accordance with ISO 2813:2014.
The method described in the patent can be used to produce a metallic substrate with a functional chromium layer for various applications, including photovoltaic devices such as solar cells. The chromium layer in these applications should have a thickness ranging from 75 to 1000 nm.
Overall, this patent presents a novel method for electrodeposition of a functional or decorative chromium layer onto metallic substrates, offering potential applications in various industries, particularly in the production of photovoltaic devices.