JPH0219198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an iron/phosphorous electroplating bath capable of producing a glazed coating with excellent wear resistance. Conventionally, sliding members such as the skirt portion of a piston that slide with a cylinder bore have been subjected to various surface treatments in order to improve their wear resistance and seizure resistance. As one of the surface treatment methods for such sliding members, it is conventionally known to form an iron/phosphorus plating film on the surface of the sliding member using an iron/phosphorus electroplating bath. Formation of an iron/phosphorus plating film can improve the wear resistance and seizure resistance of sliding parts, but in order to further extend the life of sliding parts, the wear resistance of the iron/phosphorus plating film can be improved. It is desirable to further improve the In view of the above circumstances, the present inventors conducted intensive studies on further improving the wear resistance of iron/phosphorous plating coatings, and found that iron containing divalent iron ions and hypophosphite・Aluminum compounds are added to the phosphorus electroplating bath so that the aluminum ion content is 0.05 to 5 g per plating film, and titanium compounds and/or zirconium soluble in the iron/phosphorus electroplating bath are added. Bathing bath 1
iron bath containing 0.05 to 10 g per bath or divalent iron ions and phosphorous acid and/or phosphite.
The aluminum compound is added to the phosphorus electroplating bath so that the aluminum ion content is 0.05 to 1 per plating bath.
Plating is carried out in a bath in which 0.05 to 10 g of titanium and/or zirconium compounds soluble in the iron/phosphorous electroplating bath are added as titanium and zirconium per plating bath. The present inventors have discovered that, when carried out, a matted coating with excellent wear resistance can be obtained and the above object can be achieved, and the present invention has been completed. That is, as an iron/phosphorous electroplating bath, a plating bath containing divalent iron ions, hypophosphorous acid and/or hypophosphite and aluminum ions, or a plating bath containing divalent iron ions, phosphorous acid and/or hypophosphite and aluminum ions, When a tightening bath containing phosphite and/or phosphite as a main component is used, a tightening film with no cracks and excellent mechanical properties can be obtained. To explain further, iron/phosphorus electroplating baths that contain divalent iron ions and hypophosphorous acid or its salts, and further contain boric acid, ammonium chloride, etc., are conventionally known. When iron/phosphorus electroplating is performed using a plating bath, many cracks occur in the cross section of the resulting iron/phosphorus plating film, and these cracks are particularly important in applications that require mechanical performance. The cracked iron/phosphorus plating film itself has extremely low toughness, and the wedge effect reduces the toughness of the plated material itself. However, a plating bath containing divalent iron ions, hypophosphorous acid and/or hypophosphite, and aluminum ions as described above as an iron/phosphorous electroplating bath, or a plating bath containing divalent iron ions and aluminum ions, When a sliding member or the like is plated using a tightening bath containing phosphoric acid and/or phosphite as a main component, a crack-free plated film can be obtained. Further, by adding a titanium compound and/or a zirconium compound in an amount of 0.05 to 10 g as titanium and zirconium in addition to the above-mentioned components, even more remarkable wear resistance is imparted to the above-mentioned crack-free plated coating. The present invention will be explained in more detail below. The iron/phosphorus electroplating bath according to the present invention contains divalent iron ions, a water-soluble phosphorus compound, a titanium compound, and/or a zirconium compound. In this case, the titanium compound and zirconium compound used are those soluble in the iron/phosphorus plating bath, such as Na ₂ TiF ₆ , K ₂ TiF ₆ , (NH ₄ ) ₂ TiF ₆ ,
Ti( _SO4 ) ₂ , _{Na2ZrF6 , K2ZrF6 ,} ( _NH4 ) _{2ZrF6 ,}
One type such as Zr(SO ₄ ) _{2.4H 2} O can be used alone or two or more types can be used in combination. The amount of these titanium compounds and zirconium compounds to be added is 0.05 to 10 g, particularly 0.1 to 5 g of titanium or zirconium in the plating bath 1. If the amount of titanium or zirconium is too small, the effect of improving the abrasion resistance of the plated film obtained will not be sufficient, and if it is too large, it will not dissolve in the bath and will remain in a suspended state, resulting in a rough texture on the surface of the plated film. It adheres, impairs the appearance, and has a negative impact on wear resistance. Divalent iron ions and a water-soluble phosphorus compound are further added to the iron/phosphorus electroplating bath to which the titanium compound and zirconium compound are added. Here, the source of divalent iron ions is not particularly limited, but examples include ferrous sulfate, ferrous chloride,
Examples include ferrous sulfamate, ferrous borofluoride, etc., and one of these may be used alone or in combination with two others.
More than one species can be used in combination. Also,
Although the content of divalent iron ions is not necessarily limited, it is preferably 20 to 80 g per plating bath. In addition, as water-soluble phosphorus compounds, hypophosphorous acid, hypophosphites such as sodium hypophosphite, phosphorous acid, phosphites such as sodium phosphite, etc. can be used, and one of these can be used. They can be used alone or in combination of two or more. There is no limit to the amount of these phosphorus compounds used, but it is 0.05 per plating bath.
It is preferable to set it as 20g. In this case, when hypophosphorous acid or hypophosphite is used, an aluminum compound is added to it.
In this way, when electroplating is performed using a bath containing hypophosphorous acid or hypophosphite with an aluminum compound added, or a bath of phosphorous acid or phosphite, it is possible to produce iron or iron with no cracks in the cross section. A phosphor-plated film is obtained,
This makes it possible to further improve wear resistance. That is, conventionally, when obtaining an iron/phosphorus plating film using an electroplating bath as described above, a soaking bath using hypophosphorous acid or hypophosphite as the phosphorus source was used. The plating bath yields a glossy plating film, but when the cross section was observed, it was found that many cracks had occurred. However, aluminum ions are added to the soaking bath using hypophosphorous acid or hypophosphite as a phosphorus source, or phosphorous acid or phosphorous acid is used instead of hypophosphorous acid or hypophosphite. When salt is used, it is possible to prevent the formation of cracks in the iron/phosphorus plating film. Note that aluminum compounds include aluminum sulfate, aluminum chloride, etc.
It is not limited to this. These aluminum compounds may be used alone or in combination of two or more. In addition, the content of aluminum ions in plating solution 1
0.05-5g, especially 0.1-2g per serving,
A good crack prevention effect can be obtained within this range. Furthermore, the aluminum compound may be added not only to a hypophosphorous acid bath, but also to a mixed bath of a hypophosphorous acid bath and a phosphorous acid bath, or a phosphorous acid bath. In addition to the above-mentioned components, the plating bath according to the present invention may further contain 0 to 200 g of ammonium sulfate, ammonium chloride, etc. as conductivity salts, if necessary.
Especially 20 to 150g/, 0 to 60g/, especially 20 to 50g/of boric acid etc. as a PH buffer, divalent or trivalent
As a complexing agent for valent iron ions, acidic ammonium fluoride or the like can be added in an amount of 0 to 20 g, particularly 1 to 10 g. Note that the pH of the plating bath of the present invention is preferably 0. to 3.5. When plating a desired object using the iron/phosphorous electroplating bath mentioned above, the bath temperature is room temperature to 80°C.
℃, in particular 30 to 70 ℃, and the cathode current density can be 0.5 to 30 A/ ^dm2 , in particular ² to 20 A/dm2. Furthermore, although stirring is not necessarily required, bath stirring using a cathode rocker or stirrer can be employed. Note that an iron plate is generally used for the anode. The appearance of the iron/phosphorus plating film obtained by using the iron/phosphorus electroplating bath of the present invention is generally a semi-glossy, uniform surface, and the resulting plating film has good abrasion resistance and mechanical resistance. Since it has excellent physical properties, it is suitably used for plating sliding members such as piston skirts. In this case, in order to further improve the wear resistance and seizure resistance of the plating film, the phosphorus content of the plating film is set to be less than 10%, more preferably 0.1 to 6%. It is preferable to adjust the amount of phosphorus compound in the brightening bath. EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples, but the present invention is not limited to the following examples. Example 1 A piston material made of AC8A/T6 standard aluminum alloy was used, and after being subjected to normal pretreatment (zinc replacement and copper bronze strike plating),
Using an iron/phosphorus plating bath with the following composition, 30μ iron/
A phosphorus-plated film (phosphorus content 1.0%) was formed. Next, the obtained sliding member was combined with an aluminum alloy cylinder bore material of A390/T6 standard that had been etched by electrolytic polishing or chemical polishing, and the wear and seizure tests described below were conducted. Iron/phosphorus plating bath composition and plating conditions FeSO ₄・7H ₂ O 250g/ (NH ₄ ) ₂ SO ₄ 100 〃 NaH ₂ PO ₃・2H ₂ O 1 〃 K ₂ TiF ₆ 2 〃 PH 2.1 Bath temperature 60℃ D _K 4A/dm ² Example 2 Instead of K ₂ TiF ₆ in the plating bath of Example 1
The test was conducted in the same manner as in Example 1, except that 2 g/Na ₂ ZrF ₆ was used. Comparative Example 1 A test was carried out in the same manner as in Example 1 except that K ₂ TiF ₆ was removed from the plating bath of Example 1 and a plating bath was used. Comparative Example 2 In the plating bath of Example 1, instead of K ₂ TiF ₆
Example 1 except that 10g/NiSO ₄ 6H ₂ O was used.
It was tested in the same way. Comparative Example 3 In place of K ₂ TiF ₆ in the plating bath of Example 1
Example 1 except that 10 g of CoSO ₄ 7H ₂ O was used
It was tested in the same way. Example 3 A piston material made of aluminum alloy of AC8A/T6 standard was used, and after pre-treatment (zinc substitution and bronze strike plating), an iron/phosphorus plating bath with the following composition was used. A 30μ thick iron/phosphorus plating film (phosphorus content 4.0%) was formed. Next, the obtained sliding member was combined with an aluminum alloy cylinder bore material of A390/T6 standard that had been etched by electrolytic polishing or chemical polishing, and the same wear and seizure tests as in Example 1 were conducted. Iron/phosphorous plating bath composition and plating conditions FeCl ₂・4H ₂ O 160g/ (NH ₄ ) ₂ SO ₄ 100 〃 H ₃ BO ₃ 20 〃 NH ₄ F・HF 5 〃 Al ₂ (SO ₄ ) ₃・14 -18H ₂ O 5 〃 NaH ₂ PO ₂・H ₂ O 3 〃 Na ₂ ZrF ₆ 2 〃 PH 1.4 Bath temperature 60℃ Dk 4A/dm ² Comparative example 4 Al ₂ (SO ₄ ) from the plating bath of Example 3 ₃・14―
The test was carried out in the same manner as in Example 3, except that 18H ₂ O was omitted and a soaking bath was used. Example 4 In place of Na ₂ ZrF ₆ in the plating bath of Example 3
The test was conducted in the same manner as in Example 3 except that 2 g/K ₂ TiF ₆ was used. Comparative Example 5 In the plating bath of Example 3, ₂ g of K ₂ TiF ₆ was used instead of Na ₂ ZrF 6 and Al ₂ (SO ₄ ) ₃ .
The test was carried out in the same manner as in Example 3, except that 14-18H ₂ O was omitted and a soaking bath was used. Comparative Example 6 A test was conducted in the same manner as in Example 2, except that Na ₂ ZrF ₆ was removed from the plating bath in Example 3 and a plating bath was used. Comparative Example 7 Na ₂ ZrF ₆ and Al ₂ from the plating bath of Example 3
The test was carried out in the same manner as in Example 3, except that (SO ₄ ) ₃ ·14-18H ₂ O was removed and a soaking bath was used. Comparative Example 8 Abrasion and seizure tests were conducted in the same manner as in Example 1 by combining an AC8A/T6 standard aluminum alloy piston material with a 30 μm iron plating film formed and an A390/T6 standard aluminum alloy cylinder bore material etched by electrolytic polishing. I did this. Wear test was carried out using LFW-1 friction and wear tester.
Wear depth was evaluated. In addition, the seizure test used a mechanical testing laboratory type friction and wear tester to evaluate the seizure load. Furthermore, the plating film is cut and the cut surface is 5%
After etching with nital for 2 seconds, the presence or absence of cracks was examined using a metallurgical microscope (40x magnification).
The results are shown in Table 1. From the results in Table 1, the plating film obtained from the matting bath containing titanium compounds and zirconium compounds has no cracks and has good wear resistance (baking load).
It is recognized that the 【table】

Claims (1)

[Scope of Claims] 1. An aluminum compound is added to an iron/phosphorus electroplating bath containing divalent iron ions and hypophosphorous acid and/or hypophosphite, so that the content of aluminum ions is 0.05 per plating bath. ~5g of titanium and/or zirconium compounds soluble in the iron/phosphorus electroplating bath are added as titanium and zirconium in an amount of 0.05 to 10% per plating bath.
An iron/phosphorus electroplating bath characterized by the addition of g. 2. Add an aluminum compound to an iron/phosphorus electroplating bath containing divalent iron ions and phosphorous acid and/or phosphite so that the aluminum ion content is 0.05 to 5 g per plating bath. An iron/phosphorus electroplating bath characterized in that a titanium compound and/or a zirconium compound soluble in the iron/phosphorus electroplating bath is added in an amount of 0.05 to 10 g as titanium and zirconium per plating bath.