JPS62202082A - Treatment with composite phosphate - Google Patents

Abstract

PURPOSE:To improve the wear resistance of the surface of an iron material by forming phosphate film on the surface of the iron material and immersing the iron material in a copper salt soln. so as to convert the phosphate film into a film having small surface roughness and high lubricating oil retentivity. CONSTITUTION:A phosphate film is formed on the surface of an iron material by treatment with a phosphate such as manganese phosphate, zinc phosphate or zinc calcium phosphate. The iron material having the phosphate film is immersed in a soln. of a copper salt such as acidic copper nitrate to deposit copper in the gaps among the crystals of the phosphate film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite phosphate treatment method for forming a composite phosphate film on the surface of iron rotating and sliding parts.

(Prior art) For example, if a phosphate film is applied to the surface of iron rotating and sliding parts, such as gears and camshafts of internal combustion engines, by phosphate treatment, lubricating oil retention is improved. Because direct metal-to-metal contact is avoided, phosphate coatings have the effect of reducing wear.Therefore, phosphate coatings have been widely used in internal combustion engine gears, camshafts, cylinders, piston rings, etc.

[Problem that the invention seeks to solve]

However, in conventional phosphate coatings, the phosphate crystals have a sharp and large shape, resulting in a large surface roughness of the coating. For this reason, there was a problem in that the film was likely to peel off, and the wear resistance could not necessarily be improved.

[Means for solving problems]

The present invention was made in view of these circumstances, and provides a composite phosphate treatment method capable of producing a film that improves wear resistance.

The composite phosphate treatment method according to the present invention involves generating a phosphate film on the surface of an iron material by phosphate treatment, and then immersing the iron material in a copper salt solution.

Here, the composite phosphate film is one in which copper grains, which have a lower ionization tendency than iron, are attached between phosphate grains.

[Effect]

In the present invention, a composite phosphate film with low surface roughness and high lubricating oil retention is formed on the surface of the iron material.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a composite phosphate treatment apparatus for carrying out the composite phosphate treatment method according to the present invention, and in the figure, the reference numeral 1 indicates the composite phosphate treatment apparatus. This apparatus 1 is of an immersion type in which a phosphate treatment process is performed subsequent to the degreasing process on the surface of the iron material, 2 is a degreasing tank, and 3 is a washing tank that follows the degreasing process. Reference numeral 4 denotes a conveying device disposed above these tanks for conveying the workpiece 5 made of iron material. Behind the washing tank 3, there is a first tank that performs phosphate treatment after washing.
A processing tank 6 is provided. This first treatment tank 6 is supplied with a phosphate solution that immerses the iron material to form a phosphate film on the surface of the iron material. 7 is a washing tank provided following the first treatment tank 6. Reference numeral 8 denotes a second treatment tank provided after this water washing, in which a copper salt solution is supplied to immerse the iron material with a phosphate film formed on its surface. Reference numeral 9 denotes a drying device for washing the iron material treated in the second treatment tank 8 with water in the washing tank 10 and then drying it.

Next, to explain the formation of the film, the first treatment tank 6
The phosphate film formed by the phosphate treatment in the interior can be appropriately selected from manganese phosphate, zinc phosphate, zinc calcium phosphate, iron phosphate, tin phosphate, etc. Among these, especially Manganese phosphate is the best. In the embodiment, in order to produce this manganese phosphate, 3.1 manganese monophosphate is added to the first treatment tank 6.
A 5 to 4.0% aqueous solution was supplied and the iron material was immersed in the solution for 5 to 10 minutes while the water temperature was maintained around 85°C.

That is, the manganese monophosphate solution dissociates as shown in the following formula.

-3Mn (Hz POt)z -e- Mnl(POa)t+ 4 H3P 04 ・
- (1) When the iron material whose surface has been cleaned in the degreasing tank 2 and the water washing tank 3 is immersed in the treatment liquid in this equilibrium state, the following reaction occurs.

2 H3P O4+ F6 → Fe (Hz PO4)z 10Hz ・ ・(2)
That is, iron dissolves in the solution while generating hydrogen bubbles from the surface. Therefore, the pH of the solution at the interface between the iron surface and the solution increases. As a result, the dissociation in the above formula (1) newly proceeds from the left side to the right side, producing trimanganese phosphate. And since it is insoluble,
The moment it is formed, it precipitates as crystals on the iron surface.

As the copper salt solution in the second treatment tank 8, for example, an acidic copper nitrate solution is used. In the example, an aqueous solution containing about 1% acidic copper nitrate was used, and the iron material was immersed in the solution for 5 to 10 minutes while the water temperature was maintained at about 85°C. In this tank, since copper in the acidic copper nitrate solution has a smaller tendency to ionize than iron, a reaction as shown in equation (3) occurs, and the copper crystallizes between the manganese triphosphates. Precipitate.

Fe+Cu” −*Fe”+Cu, −・131 The photograph shown in Figure 2 shows the manganese phosphate+ produced on the surface of the iron material.
This is a microscopic photo showing the surface of a copper film magnified 1500 times. In the photo, the large rock-like areas are manganese phosphate precipitates, and the small granular areas between the manganese phosphates are copper precipitates. It is a part. Manganese phosphate is precipitated over the entire surface, and the corners are rounded compared to those in conventional manganese phosphate films. This makes it difficult to peel off. Copper has a fine shape,
It is deposited so as to fit into the hollow areas between the crystals of manganese phosphate. In other words, copper is deposited so as to even out the unevenness formed by manganese phosphate.

For this reason, compared to the surface of the film made of manganese phosphate,
The roughness of the surface of the film can be reduced to make it smooth. Furthermore, since the voids formed on the surface of the film are also extremely small, the retention of the lubricating oil impregnated into the voids can also be improved.

According to such a composite phosphate treatment method, a composite phosphate coating is generated on the surface of the iron material, which has a smaller surface roughness and a higher lubricating oil retention property than conventional phosphate coatings. Therefore, the frictional resistance generated between the surface of the iron material and the mating member is reduced, and there is no risk of peeling, so that wear resistance is improved. Further, as mentioned above, since the surface is made dense by copper, not only corrosion resistance is improved, but heat dissipation is also improved, and workability such as forging is also improved.

[Effects of the Invention] As explained above, according to the present invention, after a phosphate film is generated on the surface of an iron material by phosphate treatment, the iron material is immersed in a copper salt solution. A multipolymerized phosphate film with low roughness and high lubricating oil retention is produced.

Therefore, since the composite phosphate film has low frictional resistance and is not likely to peel off, it is possible to form a film that improves wear resistance on the surface of the iron material.

In addition, conventional processing equipment can be used for part of the processing steps, and by performing the processing separately, there is an advantage that the adjustment of the processing liquid does not become complicated.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing a composite phosphate treatment apparatus for carrying out the composite phosphate treatment method according to the present invention, and Figure 2 shows the surface of the manganese phosphate + copper film formed on the surface of iron material. This is a micrograph magnified 1500 times. 4... Conveyance device, 5... Workpiece, 6...
1st treatment tank, 8...2nd treatment tank.

Claims (1)

[Claims] A composite phosphate treatment method characterized by phosphating an iron material to generate a phosphate film on the surface and then immersing the iron material in a copper salt solution.