POWDER FOR COLD SPRAY, METHOD FOR MANUFACTURING MACROMOLECULAR COATING FILM, AND MACROMOLECULAR COATING FILM

Abstract

Powder for cold spray containing a mixture of powder of a macromolecule and nanoparticles of a ceramic. Macromolecular coating film containing a mixture of powder of a macromolecule and nanoparticles of a ceramic.

Claims

1. A powder for cold spray, comprising a mixture of powder of a macromolecule and nanoparticles of a ceramic.

2. The powder for cold spray according to claim 1, wherein nanoparticles represent from 1% by mass to 10% by mass of the mixture.

3. The powder for cold spray according to claim 1, wherein the macromolecule is an organic macromolecule having a molecular weight of at least 1 million g/mol.

4. The powder for cold spray according to claim 1, wherein the macromolecule is a thermoplastic resin.

5. The powder for cold spray according to claim 1, wherein the macromolecule is an ultrahigh molecular weight polyethylene.

6. The powder for cold spray according to claim 1, wherein the ceramic is aluminum oxide.

7. The powder for cold spray according to claim 1, wherein said powder comprises a mixture of ultrahigh molecular weight polyethylene and aluminum oxide.

8. A method for manufacturing a macromolecular coating film, said method comprising forming the film on a surface of a base material by spraying the powder for cold spray according to claim 1 on the base material using a cold spray method.

9. A macromolecular coating film obtained using the method for manufacturing a macromolecular coating film according to claim 8.

10. A macromolecular coating film comprising a mixture of powder of a macromolecule and nanoparticles of a ceramic.

11. The macromolecular coating film according to claim 10, wherein nanoparticles represent from 1% by mass to 10% by mass of the mixture.

12. The macromolecular coating film according to claim 10, wherein the macromolecule is an organic macromolecule having a molecular weight of at least 1M g/mol.

13. The macromolecular coating film according to claim 10, wherein the macromolecule is a thermoplastic resin.

14. The macromolecular coating film according to claim 10, wherein the macromolecule is an ultrahigh molecular weight polyethylene.

15. The macromolecular coating film according to claim 10, wherein the ceramic is aluminum oxide.

16. The macromolecular coating film according to claim 10, comprising a mixture of ultrahigh molecular weight polyethylene and aluminum oxide.

17. A method for manufacturing a macromolecular molded product, said method comprising spraying the powder for cold spray according to claim 1 on a base material or a mold using a cold spray method and then obtaining a molded product by removing it from the base material or the mold.

18. The powder for cold spray according to claim 2, wherein the macromolecule is an organic macromolecule having a molecular weight of at least 1 million g/mol.

19. The powder for cold spray according to claim 18, wherein the macromolecule is a thermoplastic resin.

20. The powder for cold spray according to claim 19, wherein the macromolecule is an ultrahigh molecular weight polyethylene and the ceramic is aluminum oxide.

Description

[0019] According to the invention, it is possible to provide powder for cold spray enabling the formation of a relatively thick macromolecular coating film using a cold spray method, a macromolecular coating film, and a method for manufacturing a macromolecular coating film.

[0020] FIG. 1 illustrates microscope photographs illustrating (a) alumina particles and (b) powders of ultrahigh molecular weight polyethylene (UHMWPE) which are contained in powders for cold spray of an embodiment of the invention, and (c) powders for cold spray of an embodiment of the invention.

[0021] FIG. 2 is a side view illustrating a cold spray device for spraying the powders for cold spray of the embodiment of the invention to a base material.

[0022] FIG. 3 illustrates perspective views illustrating macromolecular coating films formed by spraying the powder for cold spray of the embodiment of the invention to (a) a polypropylene base material, (b) a pure aluminum base material, and (c) an alumina base material using the cold spray device illustrated in FIG. 2.

[0023] FIG. 4 illustrates (a) a scanning electron microscope (SEM) planar image and (b) a SEM cross-sectional image of the macromolecular coating film on the pure aluminum base material illustrated in FIG. 3(b).

[0024] FIG. 5 is a SEM cross-sectional image of the macromolecular coating film on the polypropylene base material illustrated in FIG. 3(a).

[0025] FIG. 6 illustrates a SEM planar image of the macromolecular coating film on the pure aluminum base material illustrated in FIG. 3(b) and energy dispersive X-ray spectroscopy (EDX) analyzed images of O, Al, and C.

[0026] FIG. 7 illustrates a SEM planar image of the macromolecular coating film on the polypropylene base material illustrated in FIG. 3(b) and EDX analyzed images of O, Al, and C.

[0027] FIG. 8 is an EDX analyzed image of Al in a range of the SEM cross-sectional image of the macromolecular coating film on the polypropylene base material illustrated in FIG. 5.

[0028] FIG. 9 is a microscope photograph illustrating a cross-section of the macromolecular coating film on the polypropylene base material of a comparative experiment in which only UHMWPE powder having a diameter in a range of 10 m to 60 m is sprayed.

[0029] Hereinafter, a film formation experiment was carried out using the powder for cold spray according to the invention. An embodiment of the invention will be described on the basis of the experiment results.

[0030] As powder for cold spray of the embodiment of the invention, a mixture of the powder of ultrahigh molecular weight polyethylene (UHMWPE) and ceramic nanoparticles made of alumina (aluminum oxide) particles was used. The UHMWPE powder has a molecular mass of 3900 kg/mol, a melting point in a range of 130 C. to 140 C., and a density of 0.940 g/cm.sup.3, and, as illustrated in FIG. 1(b), in the experiment, UHMWPE powder having a diameter in a range of 10 m to 60 m was used. In addition, as illustrated in FIG. 1(a), alumina particles having a diameter in a range of 40 nm to 90 nm was used. As illustrated in FIG. 1(c), powder obtained by adding 3.8% by mass of alumina particles to UHMWPE powder was used as the powder for cold spray.

[0031] In the experiment, the powder for cold spray was sprayed to the surface of a base material 1 by using a low-pressure type cold spray device 10 illustrated in FIG. 2. As illustrated in FIG. 2, the cold spray device 10 includes a gas feeding opening 11, a heater 12, a powder feeder 13, and a nozzle 14. The cold spray device 10 is constituted so that pressurized carrier gas fed from the gas feeding opening 11 is heated in the heater 12 and is sprayed from the tip of the nozzle 14 together with the powder for cold spray being fed from the powder feeder 13. In the experiment, the temperature of the carrier gas heated in the heater 12 was changed in a range of 100 C. to 250 C. and the pressure of the carrier gas was changed in a range of 0.2 MPa to 0.8 MPa. In addition, the length of the nozzle 14 was set to 200 mm. In addition, as the base material 1, a polypropylene base material (polymer base material), a pure aluminum base material (metal base material), and an alumina base material (ceramic base material) were used.

[0032] For comparison, experiments were carried out under the same conditions for a case in which only UHMWPE powder having a diameter in a range of 10 m to 60 m was sprayed in addition to a case in which the powder for cold spray of the embodiment of the invention and a case in which the length of the nozzle was set to 100 mm and only UHMWPE powder having a diameter in a range of 10 m to 60 m was sprayed.

[0033] FIG. 3 illustrates film formation states when the powder for cold spray of the embodiment of the invention was sprayed to the respective substrates using the cold spray method. As illustrated in FIG. 3, it was confirmed that an approximately 1 mm-thick macromolecular coating film was formed on the polypropylene base material, an approximately 4 mm-thick macromolecular coating film was formed on the pure aluminum base material, and an approximately 3 mm to 4 mm-thick macromolecular coating film was formed on the alumina base material. When sprayed to the polypropylene base material, the temperature of the carrier gas was 150 C. and the pressure thereof was 0.3 MPa. When sprayed to the pure aluminum base material and the alumina base material, the temperature of the carrier gas was 250 C. and the pressure thereof was 0.4 MPa.

[0034] A planar image and a cross-sectional image of the macromolecular coating film formed on the pure aluminum base material obtained using a scanning electron microscope (SEM) are illustrated in FIG. 4 and a SEM cross-sectional image of the macromolecular coating film formed on the polypropylene base material is illustrated in FIG. 5. In addition, a SEM planar image of the macromolecular coating film formed on the pure aluminum base material and the analyzed images of O, Al, and C in the planar image range obtained through energy dispersive X-ray spectroscopy (EDX) are illustrated in FIG. 6 and a SEM planar image of the macromolecular coating film formed on the polypropylene base material and the EDX analyzed images of O, Al, and C in the planar image range are illustrated in FIG. 7. In addition, FIG. 8 illustrates an EDX analyzed image of Al in the range of the SEM cross-sectional image on the polypropylene base material illustrated in FIG. 5. In the EDX analyzed images of O, Al, and C, portions with a large amount of each of the elements are displayed to be bright.

[0035] As illustrated in FIG. 4(a), it can be confirmed that the UHMWPE particles are deposited on the surface of the base material without being melted and form a film. In addition, as illustrated in FIGS. 4(b) and 5, it can be confirmed that the UHMWPE particles are tightly deposited on the surface of the base material. As illustrated in FIGS. 6 and 7, it can be confirmed that oxygen (O) is rarely observed on the surface of the formed coating film and the film is not oxidized. In addition, it can be confirmed that carbon (c) is observed on the surfaces of the particles and thus, the particles are the UHMWPE particles. In addition, as illustrated in FIGS. 6 to 8, it was observed that aluminum (Al) was distributed on the interfaces between the respective UHMWPE particles. From this observation, it can be considered that the alumina particles connect the interfaces between the respective UHMWPE particles and increase the strengths of adhesion between the respective particles.

[0036] As illustrated in FIG. 9, in the comparative experiment in which only UHMWPE powder having a diameter in a range of 10 m to 60 m was sprayed, it was confirmed that, in the case of the polypropylene base material being used, only one layer of a 45 m-thick film was formed. In the pure aluminum base material and the alumina base material, the sprayed powder was bounded back on the surface of the base material and thus a film was rarely formed. In the experiments, the temperature of the carrier gas was in a range of 100 C. to 150 C. and the pressure thereof was in a range of 0.2 MPa to 0.8 MPa.

[0037] In the comparative experiment in which the length of the nozzle was set to 100 mm which was half of the length of the nozzle in the experiment and only UHMWPE powder having a diameter in a range of 10 m to 60 m was sprayed, it was not possible to form a film on any of the base materials. This is considered to be because the exposure time of the UHMWPE particles to a high-temperature gas in the nozzle was short.

[0038] From the above-described experiment results, the following facts were confirmed. That is, when the powder for cold spray of the embodiment of the invention, which is obtained by mixing the nanoparticles of alumina which is ceramic with the powder of the ultrahigh molecular weight polyethylene (UHMWPE), is sprayed to the base material using the cold spray method, it is possible to form a coating film having a relatively thick thickness of 1 mm or more on the surface of the base material. This is considered to be because the nanoparticles connect the interfaces between the particles in the powder of the macromolecule.

[0039] In addition, when the powder for cold spray of the embodiment of the invention is sprayed to the base material using the cold spray method, it is possible to form an unoxidized film at a higher film formation rate compared with the spraying method. In addition, it is also possible to suppress the thermal alteration of the particles of the macromolecule. Since the ultrahigh molecular weight polyethylene used had poor fluidity when melted, the injection molding thereof was difficult, but the use of the cold spray method enables the easy formation of a coating film. In addition, when the ultrahigh molecular weight polyethylene (UHMWPE) is used, it is possible to form a coating film that is excellent in terms of not only corrosion resistance or chemical resistance but, particularly, also impact resistance or abrasion resistance.