Product Introduction

Anodizing Technology for Aluminum
High corrosion resistant sealing agent 5E161
Nippon Hyomen Kagaku Kabushiki Kaisha R & D center

Introduction

Treatment Process

Anodic oxidation treatment, widely known as anodizing

5E161 can be used as an alternative to conventional nickel(alumite), is a surface treatment for aluminum alloys.

acetate sealing.

Anodizing generally includes the subsequent sealing process,Anodic oxidation→(Dyeing)→

which improves corrosion and abrasion resistance, andSealing 5E161→Drying

allows for improved design through dyeing, making it a*Water rinsing is always performed after each of thetechnology widely used in the industrial field.

above treatment processes.

On the other hand, it has been confirmed that the corrosion
resistance of anodizing varies greatly depending on the typeMechanismsof aluminum material. Copper-free expanded materials are

The anodizing is generally performed in the following

easy to obtain corrosion resistance, while die-cast materials

steps (Figure 1). First, aluminum alloy material is immersed

such as ADC12 are difficult to obtain corrosion resistance.1

in a special electrolytic solution to form an oxide film withWe have developed a new sealing agent, 5E161, whichpores on the material surface by anodic electrolysis. If

provides excellent corrosion resistance in cast and die-castnecessary, the material is dyed in the next process. Finally, amaterials. The technology of this agent is therefore

pore sealing treatment is performed to seal the pores.2

introduced.
Naturaloxide film

Growth ofoxide film

Product Description
5E161 is a sealing agent that improves the corrosion
resistance of anodic oxide coatings on aluminum alloys.
Compared to conventional nickel acetate sealing and boilingwater sealing, it offers outstanding corrosion resistance on

Aluminum
base material
Anodized aluminum
film formationdyes

sealcastings and die-cast materials. Furthermore, it can beprocessed at lower temperatures and in shorter time.
Features・ Superior corrosion resistance compared to conventional

Figure 1: General Anodizing Process

nickel acetate sealing and boiling water sealing.
・ Treatment can be performed at 40°C, which reduces

Conventional boiling water sealing and nickel acetate

energy costs compared to high-temperature treatment.

sealing are considered to be hydration sealing, and nickel

・ Standard treatment time is as short as 3 minutes, making

acetate sealing is further considered to be hydration sealing

it easy to work with.
・ We have a lot of experience in die-casting workpieces
that require corrosion resistance.

with nickel deposited as hydroxide.3
Al2O3＋H2O

Al2O3・H2O

Ni2+＋2OH-

Ni(OH)2(Boehmite)On the other hand, the new 5E161 is a trivalent chromiumand cobalt-containing agent and is a metal-filled seal. The
sealing mechanism is thought to be based on the following
20221025 JASCO Nippon Hyomen Kagaku Kabushiki Kaisha 1[Product Introduction] High Corrosion Resistant Sealing Agent 5E161

reaction.

rust, while the new sealing agent improved corrosion-Al2O3+6F +3H2O

2AlF3＋6OH

3+-Cr(OH)32+-Co(OH)2Cr ＋3OHCo ＋2OH

-resistance to the extent that only minor white rust wasobserved after 1200 hours.

The gel portion of the anodized aluminum pore isAgents

positively charged, and the negatively charged fluorine ions0h24 h240 h1200 hNewadsorb and react to produce aluminum fluoride andhydroxide ions. Next, chromium and cobalt ions react withsealinghydroxide ions to form metal hydroxides. These reactions

agent

are thought to coprecipitate aluminum fluoride and metal

5E161hydroxides and seal pores.

NickelFigure 2 shows the results of glow discharge spectroscopy

acetate(GDS) of anodized aluminum material sealed with the new

sealingsealant. Many film components were present in the surface

agent

layer, and film components were observed deep into thepores (about 3 μm). It is thought that high corrosion

Figure 3: Salt Spray Test Results of ADC12 Material (JIS Z

resistance is obtained even in castings and aluminum die-2371)

cast materials due to the barrier effect of the new sealant
5E161, in which the pore-sealing components fill and seal

In Closing

deeply and the chemical components are also deposited on

5E161 is an effective sealing agent, especially for die-cast

the surface layer.

materials

wherecorrosion

resistanceisrequired.

Furthermore, compared to nickel acetate-based sealing
agents, 5E161 can be processed at lower temperatures for

A1100材上新封孔剤によるGDS分析結果
GDS
analysis resultswith new sealing agent 5E161
on A1100 material

shorter periods of time, and improved productivity can be40expected.

ＡｌM ass（(%)% ）Mass30

When castings are anodized, regardless of the type ofＯsealing agent, they will have a blackish color. For this reason,

20

black staining is often chosen for dyeing castings after

10Ｃｒanodizing. By using black dye 5E158, which is suitable for

Ｃｏ001

2345

67

8

深さ方向（μm）
Depth
direction(μm)

this new sealing agent, a black appearance can be obtainedeven in a short time.

Figure 2: GDS Analysis Results of New Sealing AgentReferences

5E161 Treated Product (trace elements are excluded from

1: Japan Research Institute of Material Technology;
Hyoumensyoritaisaku Q&A 1000, p.98 (1998)

the search)

2: Toshihiko Sato, Kyoko Kaminaga; THEORIES OF
The results of the salt spray test of the new 5E161 andANODIZED ALUMINUM 100 Q & A, p.15 (1997)

nickel acetate sealing agents are shown in Figure 3. 24 hours

3: Japan Research Institute of Material Technology;

of salt spray on ADC12 material with conventional nickel

Hyoumensyoritaisaku Q&A 1000, p.113 (1998)

acetate-based sealing agent showed the occurrence of white

Product namePurposesMechanism

5E161AB

Sealing agent for aluminum anodic oxide film

Metal-filled seals

5E158

Black dye for anodizing aluminumDyes

20221025 JASCO Nippon Hyomen Kagaku Kabushiki Kaisha 2