# US 11,908,600 B2 · Preparation device and method of ceramic coating on a sintered type NdFeB permanent magnet

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- Number: US 11,908,600 B2
- Document ID: US11908600B2
- Status: Granted
- Kind: B2
- Application number: 17/467,473
- Filed: 2021-09-07
- Published: 2022-03-10
- Granted: 2024-02-20
- Earliest claimed: 2020-09-07
- Assignees: Yantai Dongxing Magnetic Materials Inc.
- Applicants: Yantai Dongxing Magnetic Materials Inc.
- Inventors: Chuanshen Wang; Kunkun Yang; Zhongjie Peng; Daoning Jia; Kaihong Ding
- Web page: https://patentgrep.com/patent/US11908600B2

## CPC

- H01F 1/0577: {sintered}
- H01F 41/026: {protecting methods against environmental influences, e.g. oxygen, by surface treatment (magnetic particles with skin H01F1/061, H01F1/09, H01F1/24, H01F1/33 and G11B5/706)}
- C09D 1/00: Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
- C09D 5/084: {Inorganic compounds}
- C23C 18/122: {Inorganic polymers, e.g. silanes, polysilazanes, polysiloxanes}
- C23C 18/1241: {Metallic substrates}
- C23C 18/1295: {with after-treatment of the deposited inorganic material}
- H01F 7/02: Permanent magnets {[PM]}
- H01F 41/0253: {for manufacturing permanent magnets}
- B05B 12/32: Shielding elements, i.e. elements preventing overspray from reaching areas other than the object to be sprayed (nozzles with integral shielding elements B05B1/28)
- B05B 14/00: Arrangements for collecting, re-using or eliminating excess spraying material (arrangements integral with nozzles B05B1/28)
- B05D 1/02: performed by spraying
- B05D 3/0254: {After-treatment}
- B05D 2202/00: Metallic substrate
- B05D 2401/10: Organic solvent (B05D2401/21 takes precedence)
- B05D 2518/12: Ceramic precursors (polysiloxanes, polysilazanes)
- B05D 2601/26: Abrasives
- C23C 18/04: Pretreatment of the material to be coated (C23C18/06 takes precedence)
- Y02P 70/10: Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- 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)
- B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D)
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The disclosure relates to a preparation device and method of forming a ceramic coating on a sintered type NdFeB permanent magnet. The preparation device comprises a holding barrel, a pump body, a spraying system, and a fixture mechanism. The pump body is connected with the holding barrel and the spraying system and the spraying system is located above the fixture mechanism and there is a distance between the spraying system and the fixture mechanism. The fixture mechanism is connected with a recovery bucket through a pipeline, and the recovery bucket is connected with the holding barrel through the pipeline. The spraying system comprises a nozzle, wherein the inlet of the nozzle is connected with the pipeline of the pump body. The fixture mechanism comprises a support plate, an upper recovery trough plate and a lower recovery trough plate, wherein the lower recovery trough plate is located above the support plate.

## Claims

### Claim 1

A preparation device for ceramic coating on a sintered NdFeB permanent magnet, the preparation device comprising a holding barrel, a pump body, a spraying system, and a fixture mechanism,
wherein the pump body is connected with the holding barrel and the spraying system and the spraying system is located above the fixture mechanism and there is a distance between the spraying system and the fixture mechanism;
the fixture mechanism is connected with a recovery bucket through a pipeline, and the recovery bucket is connected with the holding barrel through the pipeline; the spraying system comprises a nozzle, wherein the inlet of the nozzle is connected with the pipeline of the pump body;
the fixture mechanism comprises a support plate, an upper recovery trough plate and a lower recovery trough plate, wherein the lower recovery trough plate is located above the support plate, the lower recovery trough plate is symmetrically arranged on both ends of the upper recovery trough plate; and
the outlet of the nozzle is located above a containment space of the spraying system.

### Claim 2 (depends on 1)

The method of claim 1, wherein the outlet of nozzle is a plurality of ejection points, which are set into a dot-matrix structure.

### Claim 3 (depends on 1)

The method of claim 1, wherein the spraying system also includes an inverted funnel shaped recovery tank, the top of the recovery tank is fixed on the pipeline and through the pipeline, or fixed on the top of the nozzle, the bottom end side of the recovery tank is fixed on both sides of the nozzle.

### Claim 4 (depends on 1)

A method of forming a ceramic coating on a sintered NdFeB permanent magnet, wherein a layer of a pre-ceramic slurry is sprayed on a surface of the sintered NdFeB permanent magnet, dried and cured by heat-treatment to form the ceramic coating, the method comprising the following steps:
a) Preparing of a pre-ceramic slurry including 10 to 50% polysilazane, 5 to 10% ceramic filler, 30 to 70% organic solvent, 5 to 10% adhesive, and 0 to 1% other additives;
b) Fixing the NdFeB magnet in the preparation device as defined in claim 1;
c) Transferring the pre-ceramic slurry formed in step a) to the nozzle of the preparation device through the pump body, wherein the nozzle vertically sprays the pre-ceramic slurry on a surface of the NdFeB magnet and wherein a distance between the nozzle and the NdFeB magnet is 5 to 50 mm; and
d) Drying the pre-ceramic coating on the sprayed surface of the NdFeB magnet and curing the dried pre-ceramic coating to a ceramic coating by heat-treatment.

### Claim 5 (depends on 4)

The method of claim 4, wherein before step a), the surface of the NdFeB permanent magnet is degreased, sequentially treating the degreased surface: the degreased surface is cleaned with pure water, the surface is cleaned with 3% to 5% nitric acid solution, the surface is cleaned with pure water, ash is removed with ultrasonic wave, the surface is dehydrated with 99% alcohol, and the surface is dried in an oven at 50 to 60° C.

### Claim 6 (depends on 4)

The method of claim 4, wherein NdFeB permanent magnet is a square NdFeB permanent magnet or an irregular shaped NdFeB permanent magnet.

### Claim 7 (depends on 4)

The method of claim 4, wherein ceramic fillers include one or more of silicon oxide, alumina, titanium oxide, magnesium oxide, zinc oxide, iron oxide, zirconia, tungsten oxide, tungsten carbide, boron carbide, silicon carbide, titanium carbide, silicon nitride, zirconium boride, titanium boride, and rare earth oxides.

### Claim 8 (depends on 4)

The method of claim 4, wherein the organic solvent is an ester compound, ether compound, alicyclic hydrocarbon compound, or aliphatic hydrocarbon compound.

### Claim 9 (depends on 4)

The method of claim 4, wherein adhesive is an epoxy resin, acrylic acid, silicone, polyurethane, rubber or a mixture thereof.

### Claim 10 (depends on 4)

The method of claim 4, wherein drying of the pre-ceramic coating is performed at a temperature of 50 to 400° C. for 0.1 to 1 h, curing the pre-ceramic coating is performed at a temperature of 400 to 750° C. for 0.5 to 4 h, and a thickness of the ceramic coating is 5 to 35 μm.