JPS60131993A - Iron-phosphorus electroplating bath - Google Patents

Abstract

PURPOSE:To obtain an Fe.P electroplating bath giving an Fe-P film which does not crack by using bivalent Fe ions, hypophosphorous acid and/or hypophosphite and Al ions as essential components. CONSTITUTION:This Fe.P electroplating bath contains 20-80g/l bivalent Fe ions, 0,01-15g/l (expressed in terms of NaH2PO2.H2O) hypophosphorous acid and/or hypophosphite and 0.05-5g/l Al ions. To the plating bath may be added <=200g/l electrically conductive salt such as ammonium sulfate or ammonium chloride, <=60g/l pH buffer such as boric acid and <=20g/l complexing agent for bi- or tervalent Fe ions such as acidic ammonium fluoride. The plating bath is preferably adjusted to 0.5-3.5pH. When an article is plated, the temp. of the bath is kept at room temp. -80 deg.C, and the current density of the cathode at 0.5-30A/dm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an iron/phosphorus electroplating bath capable of obtaining an iron/phosphorus plating film without cracks.

The iron/phosphorus plating film is harder than the iron plating film, so by forming the iron/phosphorus plating film on sliding parts such as the piston skirt, wear resistance and
This can be expected to improve seizure resistance.

However, conventional iron/phosphorous electroplating baths containing divalent iron ions, hypophosphorous acid or its salt, and further containing boric acid, ammonium chloride, etc. are known, but the present invention According to their studies, when iron/phosphorus electroplating is performed using this type of plating bath, many cracks occur in the cross section of the resulting iron/phosphorus plating film, and these cracks particularly affect mechanical performance. We found that this poses a major obstacle in terms of the required applications. That is, the cracked iron/phosphorus plating film itself had extremely low toughness, and the wedge (notch) effect reduced the toughness of the plated material itself.

For this reason, the present inventors have investigated an iron/phosphorus electroplating bath that can obtain a crack-free iron/phosphorous plating film, and have found that divalent iron ions and hypophosphorous acid and/or hypophosphorous When aluminum ions are added to a plating bath containing an acid salt, the resulting iron/phosphorus plating film has no cracks and has excellent mechanical properties. It was discovered that the present invention is very effective as a plating bath for forming plating baths.

The present invention will be explained in more detail below.

The iron/phosphorus electroplating bath according to the present invention contains divalent iron ions, hypophosphorous acid and/or hypophosphite, and aluminum ions.

Here, the source of divalent iron ions is not particularly limited, but examples include ferrous sulfate, ferrous chloride, ferrous sulfamate, and ferrous borofluoride. One type can be used alone or two or more types can be used in combination. Further, the content of divalent iron ions is not necessarily limited, but it is preferably 20 to 80.9 per 1/metal bath.

Hypophosphorous acid and hypophosphite are used as a source of phosphorus for iron/phosphorus plating films, and their content varies depending on the phosphorus content of the iron/phosphorus plating film required. Normal plating bath 11 per Na)it Po
t-) 0.01 to 15# as 1.0.

In particular, it is preferably 0.05 to 101. By changing the content of hypophosphorous acid or hypophosphite depending on the bath of the present invention, an iron/phosphorus plating film having a phosphorus content of usually 0.1 to 9.9% can be obtained. In addition, sodium hypophosphite etc. can be used as a hypophosphite. Furthermore, in the present invention, phosphite or phosphite can be used in combination with hypophosphorous acid or hypophosphite. In this case, the content of phosphorous acid and phosphite is
NaH, PO3・2H, (J as 2
(,1,9 or less, particularly 1011 or less.

As mentioned above, the bath of the present invention contains divalent iron ions, hypophosphorous acids, and aluminum ions instead of J. This can be prevented. In this case, the source of aluminum ions includes aluminum sulfate, aluminum chloride, aluminum alum, etc., but is not limited thereto. In addition,
In the present invention, one type of these aluminum compounds may be used alone, or two or more types may be used in combination. In addition, in the present invention, the content of aluminum ions is 0.05 to 5 g, particularly 0.1 g per plating solution 11.
It is preferable to set the amount to 2 g, and within this range, a good rack prevention effect can be obtained. On the other hand, if the aluminum ion content is less than 0.051/l, the effect of preventing crack generation may not be sufficiently exhibited, and if it is more than 5 Fl/l, the adhesion between the plating film and the material may deteriorate.

The plating bath according to the present invention contains the above-mentioned components and, if necessary, further contains ammonium sulfate, ammonium chloride, etc. as a conductivity salt from 0 to 20,011 μm, especially from 20 to 15 μm.
oFl/11-Buffering agent such as boric acid from 0 to 601/l
In particular, acidic ammonium fluoride or the like is used as a complexing agent for divalent or trivalent iron ions of 20 to 501/m.
//l, especially 1 to 109/l can be added.

In the plating bath of the present invention, ... is preferably 0.5 to 3.5.0 When a desired object to be plated is plated using the above-mentioned iron/phosphorus electroplating bath, the bath temperature is room temperature to 80°C. , especially 30~
The temperature can be set to 70°C, and the cathode current density is 0.5~
30 A/dm, especially 2 to 2oA/dm. Furthermore, although stirring is not necessarily required, bath stirring using a cathode rocker or stirrer may also be employed. Note that an iron plate is generally used for the anode.
The appearance of the phosphor plating film is generally semi-glossy and uniform, and there is no crack in the resulting film, and it has excellent mechanical properties, so it can be used on sliding parts such as the skirt of a piston. , and other O suitable for plating.The present invention will be specifically explained below by omitting Examples and Comparative Examples, but the present invention is not limited to the following Examples. 1] Fe3O4・71 (to 25011/13NyaC75
Q // LeBO320 // NH,F -HF SI! /1 Alv (SO4)s ・14-18H, 01/1Na
) i, PO,” H2O0, i inFkI 1 , 8 [Example 2] 1j'eC6t-4H201601/13(NL)t
so4 100 // H3BO320tt Nl (4F-H11'5〃 Alt (S (J4) s・14=181-1,0
5 //Na)itPOt-I-1tu 3 ttp
H1,4 [Example 3] Fe (NHz 5Os)t 5011/1 as Fe
NH4CA' 5 tt NH*F-HF 5 n A4 (SO4)3・14-18 Ht O2//Na
H2PO, -H, Oto tt NaHt PO8.2H201 // j1 2.4 Next, using the above plating bath, the bath was heated at 1160°C.

30μ of iron was applied to AC8A-T6 aluminum alloy pretreated by a known method under Dk4A/dd conditions.
Phosphorus electroplated.

For comparison, using the plating bath of the following comparative example, AC8A-1 was prepared under the conditions of bath temperature 55°C and Dk IOA/di
6 aluminum alloy was subjected to 30μ iron/phosphorus electroplating.

[Comparative example]

FeCTo” 4Ht0 80,!?/lF'eS
O4・7H20100tt (NH4), 8042 s u NaH2P0. - H,010//PH1,4 Table 1 shows the appearance, hardness, and phosphorus content of the obtained iron/phosphorus plating film.

In addition, after cutting the plating film and etching the cut surface with 5% nital for 2 seconds, it was
The presence or absence of cracks was examined using K (0x). The results are also listed in Table 1.

Table 1 further shows that 20μ
A rotational fatigue test of a metal slant was conducted based on J 1 S Z2274 using a specimen coated with iron and phosphorus as a sample. The results are shown in Table 2.

Table 2 From the results shown in Table 2, it is recognized that the iron/phosphorus plating film obtained from the bath of the present invention has good mechanical properties.

Applicant Uemura Kogyo Co., Ltd. Toyota Motor Corporation Agent: Patent Attorney Takashi Kojima

Claims (1)

[Claims] An iron/phosphorus electroplating bath characterized by containing divalent iron ions, hypophosphorous acid and/or hypophosphite, and aluminum ions. 2.' The plating bath according to claim 1, wherein the content of aluminum ions is 0.05 to 5 g per plating bath.