# US 11,306,410 B2 · Anti-coking nanomaterial based on stainless steel surface, and preparation method therefor

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- Number: US 11,306,410 B2
- Document ID: US11306410B2
- Status: Granted
- Kind: B2
- Application number: 16/326,174
- Filed: 2017-08-16
- Published: 2019-06-20
- Granted: 2022-04-19
- Earliest claimed: 2016-08-16
- Assignees: Shenzhen Candortech Incorporated Company
- Applicants: Shenzhen Candortech Incorporated Company
- Inventors: Chao Chen
- Web page: https://patentgrep.com/patent/US11306410B2

## CPC

- C25D 9/10: on iron or steel
- B01D 3/10: Vacuum distillation (B01D3/12 takes precedence)
- C10G 9/16: Preventing or removing incrustation
- C10G 75/02: by addition of corrosion inhibitors
- C10G 75/04: by addition of antifouling agents
- C21D 1/18: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
- C23C 8/02: Pretreatment of the material to be coated (C23C8/04 takes precedence)
- C23C 8/42: only one element being applied
- C23C 22/24: containing hexavalent chromium compounds
- C23C 22/78: Pretreatment of the material to be coated
- C23F 1/14: Aqueous compositions
- C23F 1/40: for etching other metallic material
- C23F 17/00: Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25 (coating for obtaining at least two superposed coatings either by methods not provided for in a single one of main groups C23C2/00 - C23C26/00, or by combinations of methods providedfor in subclasses C23C and C25D, C23C28/00)
- C23G 1/19: Iron or steel
- C25D 3/08: Deposition of black chromium {, e.g. hexavalent chromium, CrVI}
- C25D 15/00: Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C10G: CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION (cracking to hydrogen or synthesis gas C01B; cracking or pyrolysis of hydrocarbon gases to individual hydrocarbons or mixtures thereof of definite or specified constitution C07C; cracking to cokes C10B); RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS

## Abstract

An anti-coking nanomaterial based on a stainless steel surface. In percentage by weight, the nanomaterial comprises: 0 to 3% of carbon, 23% to 38% of oxygen, 38% to 53% of chromium, 10% to 35% of ferrum, 0 to 2% of molybdenum, 0 to 4% of nickel, 3.5 to 5% of silicon, 0 to 1% of calcium, and the balance of impurity elements. Also disclosed are a preparation method for the anti-coking nanomaterial, the anti-coking nanomaterial that is based on a stainless steel surface and that is prepared by using the preparation method, and a stainless steel substrate comprising the anti-coking nanocrystalline material.

## Claims

### Claim 1

A method for preparing an anti-coking nanocrystalline material characterized in that the method comprises the following steps:
(1) chemically degreasing and etching with alkali a stainless steel surface using a sodium hydroxide solution and a solution containing an alkali etching additive, followed by washing with water;
(2) oxidizing the stainless steel surface treated in the step (1) by an oxidizing solution, followed by washing with water;
(3) immersing the stainless steel surface treated in the step (2) as a cathode in an electrolyte to electrolyze, followed by washing with water; and
(4) placing the stainless steel surface treated in the step (3) at a temperature of 50-60° C. and a humidity of 60-70%, and then placing at a temperature of 35-40° C. and a humidity of 40-50% for hardening.

### Claim 2 (depends on 1)

The method according to claim 1, characterized in that, in the step (1), a temperature of the sodium hydroxide solution and the solution containing the alkali etching additive is 80-85° C.;
a concentration of the sodium hydroxide solution is 6.5-8 wt. %;
a concentration of the solution containing the alkali etching additive is 0.3-0.5 wt. %;
the alkali etching additive is an alkali etching additive to chemically etch with alkali;
the chemically degreasing and etching with alkali is carried out for 10-15 minutes; and
the washing with water is performed by using water with a temperature of 80-85° C., and a time for the washing is 3-5 minutes.

### Claim 3 (depends on 1)

The method according to claim 1, characterized in that, in the step (2), preferably, the oxidizing solution contains 200-300 g/L of CrO3;
a temperature of the oxidizing solution is 75-90° C.;
a pH of the oxidizing solution is adjusted to 0.4-1.5 by adding a H2SO4 solution into the oxidizing solution; a concentration of the H2SO4 solution is 98 wt. %;
a time for oxidizing is 15-35 minutes; and
the washing with water after oxidizing in the step (2) is performed cyclically by using water at 25-40° C. for 3-5 minutes; and a pH of the water is >3.

### Claim 4 (depends on 1)

The method according to claim 1, characterized in that, in the step (3), the electrolyte contains 100-150 g/L of CrO3, 80-100 g/L of Na2SiO3, 15-20 g/L of nano silicon nitride, and 3-5 g/L of nano silicon carbide;
a temperature of the electrolyte is 40-52° C.;
a pH of the electrolyte is adjusted to 0.5-1.5 by adding a H2SO4 solution into the electrolyte; and a concentration of the H2SO4 solution is 98 wt. %;
a current for electrolyzing is carried out in the following manner:
an initial current intensity is 40-42 A/m2, and then the current intensity is gradually reduced to 4_A/m2 according to a formula i=3+30/t, wherein i is current intensity in A/m2 and t is time in minutes;
a time for electrolyzing is 25-55 minutes; and
the washing with water is performed cyclically by using water at 25-40° C. for 3-5 minutes; and a pH of the water is >3.

### Claim 5 (depends on 1)

The method according to claim 1, characterized in that, in the step (4), the placing of the stainless steel surface treated in the step (3) at a temperature of 50-60° C. and a humidity of 60-70% is performed for 3-3.5 hours; and the placing at a temperature of 35-40° C. and a humidity of 40-50% for hardening is performed for 48-72 hours.

### Claim 6 (depends on 4)

The method according to claim 4, characterized in that, the electrolyzing is carried out for 10-25 minutes at an initial current intensity of 40-42 A/m2, and then electrolyzing at a current intensity gradually reduced to 4 A/m2 according to the formula i=3+30/t during 14-18 minutes.