US20150361575A1 - Method of surface-treating aluminum material for dissipating heat - Google Patents

Method of surface-treating aluminum material for dissipating heat Download PDF

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Publication number
US20150361575A1
US20150361575A1 US14/532,848 US201414532848A US2015361575A1 US 20150361575 A1 US20150361575 A1 US 20150361575A1 US 201414532848 A US201414532848 A US 201414532848A US 2015361575 A1 US2015361575 A1 US 2015361575A1
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US
United States
Prior art keywords
aluminum material
electrolyte
concentration
oxalic acid
anodizing
Prior art date
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Abandoned
Application number
US14/532,848
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English (en)
Inventor
Ji Yong Lee
Cheol Ung LEE
Kwang Min Yoon
Tae Ho Jeong
Dong Hyun Kim
Jung Hoon Lee
Won Sub Chung
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hyundai Motor Co
University Industry Cooperation Foundation of Pusan National University
Original Assignee
Hyundai Motor Co
University Industry Cooperation Foundation of Pusan National University
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Filing date
Publication date
Application filed by Hyundai Motor Co, University Industry Cooperation Foundation of Pusan National University filed Critical Hyundai Motor Co
Assigned to PUSAN NATIONAL UNIVERSITY INDUSTRY-UNIVERSITY COOPERATION FOUNDATION, HYUNDAI MOTOR COMPANY reassignment PUSAN NATIONAL UNIVERSITY INDUSTRY-UNIVERSITY COOPERATION FOUNDATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KIM, DONG HYUN, CHUNG, WON SUB, JEONG, TAE HO, LEE, CHEOL UNG, LEE, JI YONG, LEE, JUNG HOON, YOON, KWANG MIN
Publication of US20150361575A1 publication Critical patent/US20150361575A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic acids
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/14—Producing integrally coloured layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/18—After-treatment, e.g. pore-sealing
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/18—After-treatment, e.g. pore-sealing
    • C25D11/24—Chemical after-treatment
    • C25D11/246—Chemical after-treatment for sealing layers

Definitions

  • the present application relates to a method of surface-treating an aluminum material for dissipating heat, and more particularly, to a method of surface-treating an aluminum material for dissipating heat, which is capable of increasing the radiation heat flux to thus enhance heat dissipation performance.
  • An aluminum material is light and has high thermal conductivity and electrical conductivity. Further, when an aluminum material is subjected to surface treatment, it may be enhanced in corrosion resistance and mechanical performance and is thus widely utilized in various fields. In particular, an aluminum material has been mainly utilized in vehicle parts because of its properties.
  • an aluminum material having enhanced corrosion resistance and wear resistance through surface treatment such as anodization.
  • a film resulting from anodization has many pores and thus may exhibit a variety of colors through coloring using a dye or the surface thereof may be sealed through impregnation with a functional material.
  • Anodization for surface treatment of an aluminum material is generally performed by virtue of a sulfuric acid process using as an electrolyte a 10 ⁇ 18 wt % sulfuric acid aqueous solution.
  • the reason why such a sulfuric acid process is employed is that the electrolyte is the cheapest and power consumption is low, thus generating economic benefits.
  • the anodization technique using a sulfuric acid process is aimed to enhance wear resistance and corrosion resistance of an aluminum material, but does not take into consideration heat dissipation performance of the aluminum material.
  • the resulting oxide film layer may have a porous structure which is formed regularly and stably, which is disclosed in “Method of forming anodizing electrolyte of aluminum alloy material and composition therefor” (Patent Document 1).
  • the electrolyte may be prevented from remaining to thereby obviate the post treatment process.
  • the aluminum material is enhanced in terms of not only chemical and mechanical properties including surface strength, corrosion resistance, wear resistance, insulating properties and heat resistance, but also electrical properties including voltage resistance. However, no consideration is given of heat dissipation performance of the aluminum material.
  • Typical examples of sealing treatment for finishing the surface of the anodized aluminum material include a boiling water sealing process, a low-temperature sealing process (NiF 2 ), etc. This sealing treatment process takes account of only the protection of the oxide film on the aluminum material, without the consideration of heat dissipation performance of the aluminum material.
  • an embodiment of the present application provides a method of surface-treating an aluminum material for dissipating heat.
  • the method includes anodizing an aluminum material with an electrolyte comprising oxalic acid.
  • the surface of the aluminum material is sealed by formation of cobalt sulfide (CoS) in surface pores of the aluminum material.
  • CoS cobalt sulfide
  • the oxalic acid of the electrolyte upon anodizing may have a concentration of 0.2 ⁇ 0.8 M.
  • the electrolyte upon anodizing may have a temperature of 10 ⁇ 40° C.
  • the anodizing may be performed for at least 30 min.
  • the sealing may primarily include immersing the anodized aluminum material in a cobalt acetate solution; and secondarily immersing the aluminum material in an ammonium sulfide solution.
  • cobalt acetate (Co(CH 3 COO) 2 ) of the cobalt acetate solution may have a concentration of 100 ⁇ 250 g/L.
  • ammonium sulfide ((NH 4 ) 2 S) of the ammonium sulfide solution may have a concentration of 10 ⁇ 50 g/L.
  • an electrolyte for use in anodization includes only oxalic acid, so that the color of the resulting oxide film is closer to black, thus enhancing the heat dissipation performance of the aluminum material.
  • CoS is formed in the pores of the anodized surface, so that the surface color of the aluminum material is much closer to black, thus enhancing the heat dissipation performance of the aluminum material.
  • FIG. 1A illustrates the surfaces of oxide films depending on the temperature and time period when conventional anodization using a sulfuric acid electrolyte was performed
  • FIG. 1B illustrates the surfaces of oxide films depending on the temperature and time period when anodization using an oxalic acid electrolyte according to the present invention was performed
  • FIG. 2A illustrates the relative radiation results of the oxide films depending on the temperature and time period when conventional anodization using a sulfuric acid electrolyte was performed
  • FIG. 2B illustrates the relative radiation results of the oxide films depending on the temperature and time period when anodization using an oxalic acid electrolyte according to the present application was performed;
  • FIG. 3 illustrates the surface photographs and the relative radiation results of the aluminum materials after conventional sealing treatment and the sealing treatment according to the present application
  • FIG. 4A illustrates changes in the radiation heat flux depending on the concentration of cobalt acetate in the course of primary immersion for sealing treatment using a black sealing process according to the present application.
  • FIG. 4B illustrates changes in the radiation heat flux depending on the concentration of ammonium sulfide in the course of secondary immersion for sealing treatment using a black sealing process according to the present application.
  • the present application addresses a method of surface-treating an aluminum material for dissipating heat, wherein conditions for anodization and sealing treatment that are applied to an aluminum material are improved, so that the surface color of the aluminum material is closer to black.
  • the method of surface-treating the aluminum material for dissipating heat includes anodizing an aluminum material with an electrolyte comprising oxalic acid, and sealing the surface of the aluminum material by formation of cobalt sulfide (CoS) in surface pores of the aluminum material.
  • CoS cobalt sulfide
  • anodizing is a step of subjecting the surface of the aluminum material to anodization to form an oxide film closer to black thereon.
  • the electrolyte used for anodization may contain only oxalic acid.
  • the concentration of oxalic acid is set to 0.2 ⁇ 0.8 M, and preferably 0.3 M. Since the saturated concentration of oxalic acid at 0° C. is 0.3 M, when the concentration of oxalic acid is less than 0.2 M considering the electrolyte temperature, the power necessary for performing anodization may increase, and the density of surface pores of the oxide film may decrease. In contrast, when the concentration of oxalic acid is higher than 0.8 M, oxalic acid is not further dissolved. Hence, the concentration of oxalic acid is preferably set to 0.2 ⁇ 0.8 M.
  • the electrolyte used for the present embodiment preferably contains only oxalic acid.
  • the electrolyte may further include an acid typically useful for anodization while mainly containing oxalic acid.
  • the electrolyte may include sulfuric acid, phosphoric acid or chromic acid, in addition to oxalic acid.
  • the concentration of sulfuric acid, phosphoric acid or chromic acid is preferably set to 0.1 ⁇ 1 M.
  • a current of 1 ⁇ 5 ASD and a voltage of 50 ⁇ 150 V may be employed upon anodization.
  • the temperature of the electrolyte upon anodization may be set to 10 ⁇ 40° C.
  • the optimum temperature of the electrolyte is preferably 15 ⁇ 30° C.
  • the color of the resulting oxide film may be further darkened in proportion to an increase in the electrolyte temperature. Even when the electrolyte temperature is higher than 30° C., the extent of darkening the color of the oxide film may decrease. Taking into account the maximal darkening of the oxide film, increasing the electrolyte temperature in excess of 40° C. is unnecessary.
  • the anodization processing time is preferably 30 min or longer. As the anodization processing time increases, the resulting oxide film may become thick and thus the radiation heat flux may increase. In particular, an anodization processing time exceeding 30 min may result in maximized radiation heat flux.
  • sealing is a step of sealing the oxide film formed by anodization, so that the surface color of the aluminum material is closer to black.
  • This sealing step may include primarily immersing the anodized aluminum material in a cobalt acetate solution and secondarily immersing the primarily immersed aluminum material in an ammonium sulfide solution.
  • the concentration of cobalt acetate (Co(CH 3 COO) 2 ) of the cobalt acetate solution is 100 ⁇ 250 g/L, and the temperature of the cobalt acetate solution is 20 ⁇ 50° C., and the immersion time is preferably set to 10 ⁇ 30 min.
  • the concentration of ammonium sulfide ((NH 4 ) 2 S) of the ammonium sulfide solution is 10 ⁇ 50 g/L, and the temperature of the ammonium sulfide solution is 20 ⁇ 50° C.
  • the immersion time is 10 ⁇ 30 min.
  • sulfuric acid had a concentration of 15 wt %
  • oxalic acid had a concentration of 0.3 M.
  • the temperature of the electrolyte was changed to 0° C., 15° C. and 30° C., and the processing time was changed to 10 min, 20 min, 30 min and 40 min.
  • FIGS. 1A and 1B The results are shown in FIGS. 1A and 1B .
  • FIG. 1A illustrates the surfaces of oxide films depending on the temperature and time period when conventional anodization using a sulfuric acid electrolyte was performed
  • FIG. 1B illustrates the surfaces of oxide films depending on the temperature and time period when anodization using an oxalic acid electrolyte according to the present invention was performed.
  • the surface colors of the oxide films were gradually darkened in proportion to a decrease in the electrolyte temperature.
  • the surface colors of the oxide films were gradually darkened as in the comparative examples. Further, when a processing time of 30 min and a processing time of 40 min were applied, there was little difference between the surface colors of the aluminum materials.
  • the electrolyte temperature of 10 ⁇ 40° C. and preferably at 15 ⁇ 30° C. and also the processing time of 30 min or longer are preferable, taking into consideration heat dissipation performance.
  • FIG. 2A illustrates the relative radiation results of the oxide films depending on the temperature and time period when conventional anodization using a sulfuric acid electrolyte was performed
  • FIG. 2B illustrates the relative radiation results of the oxide films depending on the temperature and time period when anodization using an oxalic acid electrolyte according to the present invention was performed.
  • the anodized aluminum material was immersed for 30 min in deionized water at 95° C.
  • the anodized aluminum material was immersed for 30 min in an immersion solution comprising 3 g/L nickel fluoride (NiF 2 ) at 25° C.
  • FIG. 3 illustrates the surface photographs and the relative radiation results of the aluminum materials after conventional sealing treatment and the sealing treatment according to the present application.
  • the aluminum materials sealed by the boiling water sealing process and the low-temperature sealing process had a darker surface color than the non-sealed aluminum material, but the surface color of the aluminum material subjected to black sealing was the closest to black.
  • the radiation heat flux was 400 W/m 2 or greater.
  • the concentration of cobalt acetate (Co(CH 3 COO) 2 ) of the cobalt acetate solution in the primary immersion process can be confirmed to be 100 ⁇ 250 g/L.
  • the radiation heat flux was 400 W/m 2 or greater.
  • the concentration of ammonium sulfide ((NH 4 ) 2 S) of the ammonium sulfide solution can be confirmed to be 10 ⁇ 50 g/L.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
US14/532,848 2014-06-16 2014-11-04 Method of surface-treating aluminum material for dissipating heat Abandoned US20150361575A1 (en)

Applications Claiming Priority (2)

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KR1020140073159A KR20150144457A (ko) 2014-06-16 2014-06-16 방열용 알루미늄소재의 표면처리 방법
KR10-2014-0073159 2014-06-16

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JP (1) JP2016003390A (de)
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DE (1) DE102014224401A1 (de)

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KR20210026428A (ko) 2019-08-30 2021-03-10 (주)투디엠 그래핀이 코팅된 알루미늄 또는 알루미늄 합금 방열체의 제조방법 및 이에 따라 제조된 방열체
KR102403878B1 (ko) * 2020-10-29 2022-06-03 주식회사 영광와이케이엠씨 옥살산 아노다이징에서 알루미늄 합금의 후처리 방법 및 이 방법으로 제조된 알루미늄 합금
KR102480966B1 (ko) * 2021-04-14 2022-12-23 비나텍주식회사 절연 기능을 갖는 슈퍼 캐패시터 모듈의 알루미늄 단자 및 이를 포함하는 슈퍼캐패시터 모듈

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DE102014224401A1 (de) 2015-12-17
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Owner name: HYUNDAI MOTOR COMPANY, KOREA, REPUBLIC OF

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEE, JI YONG;LEE, CHEOL UNG;YOON, KWANG MIN;AND OTHERS;SIGNING DATES FROM 20141015 TO 20141016;REEL/FRAME:034102/0588

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEE, JI YONG;LEE, CHEOL UNG;YOON, KWANG MIN;AND OTHERS;SIGNING DATES FROM 20141015 TO 20141016;REEL/FRAME:034102/0588

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