JP2632287B2 - Metal film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal film, and more particularly, to a method for forming a metal film having at least one of a large number of pyramidal metal crystals or a truncated pyramidal metal crystal on a surface thereof by a plating method.

[0002]

2. Description of the Related Art Conventionally, as a metal coating of this kind, for example, in a piston for an internal combustion engine, an Fe plating layer provided for the purpose of improving abrasion resistance is provided on an outer peripheral surface of a land portion and a skirt portion of an Al alloy base material. Are known.

[0003] However, under the current situation in which the internal combustion engine tends to operate at high speed and high output, the conventional Fe plating layer has an oil retaining property, that is, an oil retaining property due to its relatively smooth sliding surface. There was a problem that the oil retention was not sufficient and the seizure resistance was poor due to poor initial conformability.

Therefore, the present applicant has previously developed an Fe plating layer having at least one of a large number of pyramidal Fe crystals or a truncated pyramidal Fe crystal on its sliding surface.

[0005] With this configuration, adjacent Fe crystals exhibit a state of biting each other, whereby the sliding surface has a large number of fine peaks and a large number of peaks formed between the peaks. And a fine valley portion and a large number of fine valley portions caused by the penetration of the ridge portion, so that the Fe plating layer has good oil retaining properties. The preferential wear of the front end portion of the Fe crystal also improves the initial conformability of the Fe plating layer.

[0006]

In order to obtain the excellent sliding characteristics as described above, it is necessary to make the pyramidal Fe crystal or the like fine and to make the particle size uniform.

An object of the present invention is to provide a method for forming the metal film capable of meeting the above requirements.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for forming a metal film having at least one of a large number of pyramidal metal crystals or a truncated pyramidal metal crystal on a surface by plating.
The output of the energy source for plating is controlled so as to draw a pulse waveform as the output rises from the minimum value to the maximum value, and then falls to the minimum value, from the start of the output rise to the start of the fall. output time is for T _ON, and as one cycle from the time of the previous rise start until the next rise start, when the cycle time T _c, the output time T _ON of
The ratio T _ON / T _c between the cycle time T _c and T _ON / T _c ≦
It is characterized in that it is set to 0.45.

[0009]

When the output of the energy source for plating is controlled as described above and the ratio T _ON / T _c of the two times is set as described above, the surface can be made finer and the grain size can be made uniform. It is possible to form a metal film having a large number of pyramidal metal crystals and the like, and the abundance S of pyramidal metal crystals and the like on the surface can be S ≧ 40%.

Thus, for example, in a piston having the metal film, the metal film exhibits excellent sliding characteristics under lubrication. Further, when the abundance S is set to S ≧ 90%, the sliding characteristics of the metal film without lubrication can be improved.

However, the ratio T _ON / T _{c of} both times is T _ON / T
_{When c} > 0.45, the abundance S of pyramidal metal crystals or the like becomes S <40%, and the significance of providing such metal crystals or the like is lost.

[0012]

1 and 2 show a piston 1 for an internal combustion engine.
Has a base material 2 made of an Al alloy, and a land portion 3 _{1 of the} base material 2.
And the skirt portion 3 ₂ outer circumferential surface, a layered slide surface construction 4 as a metal film is formed by plating.

As shown in FIG. 3, the sliding surface structure 4 is composed of an aggregate of metal crystals having a body-centered cubic structure (bcc structure). The aggregate grows in a columnar shape from the base material 2 and has a large number of (hhh) oriented metal crystals with the (hhh) plane directed toward the sliding surface (surface) 4a with the cylinder bore inner wall 5 with the Miller index. Have.

In forming the sliding surface structure 4, an electroplating method is applied. At this time, as shown in FIG. 4, the current (output) I plating power source (energy source), the current I
Rises from the minimum current Imin to the maximum current Imax ,
Next, the pulse current is controlled so as to draw a pulse waveform as the time T elapses as the current decreases to the minimum current Imin .

The energizing time (output time) from the start of the rise of the current I to the start of the fall thereof is T _ON, and the cycle from the start of the previous rise to the start of the next rise is defined as one cycle, and the cycle time is defined as T _ON. When _Tc , the energizing time T
The ratio between _ON and the cycle time T _c , that is, the time ratio T _ON / T _c
Is set to T _ON / T _c ≦ 0.45.

[0016] CDmi In this case, the minimum current density CDmin
n = 0 and the average current density CDm, eg, CDm
By setting ≧ 2.5 A / dm ² , the abundance S of the (hhh) oriented metal crystal can be set to S ≧ 40%.

On the other hand, the minimum current density CDmin is defined as CDmin =
0 and the time ratio T _ON / T _c to T _ON / T _c ≦ 0.35
In addition, the average current density CDm is set to CDm ≧ 3.5 A / dm.
^When each is set to ² , the abundance S of (hhh) oriented metal crystals can be set to S ≧ 90%.

Under the above formation conditions, when the existence ratio S of the (hhh) oriented metal crystal is set to S ≧ 90%, substantially the entire sliding surface 4a is formed into a hexagonal pyramid (or hexagonal pyramid) as shown in FIG. trapezoid) metal crystals forming, i.e. it is possible to form an aggregate of Rokuryo metal crystals 7 ₁ having a ridge line 6 of six. The Rokuryo metal crystals ₇₁ forms a triangular pyramid shape shown in FIG. 6 (or triangular pyramid frustum) (hhh) oriented metal crystals, i.e. three in comparison with Sanryo metal crystals 7 ₂ with a ridge 6 The average particle size is small,
And the particle size is also substantially uniform. (Hhh) In the oriented metal crystal, there is a correlation between the particle size and the height, and therefore, the fact that the particle size is substantially uniform means that the height is also substantially equal.

[0019] Moreover, in these Rokuryo metal crystals 7 _1, phase Tonariru those exhibits a state that bite into each other. Thus the sliding surface 4a is a three-ridge as compared with the case where the metal crystals 7 ₂ is formed from a larger surface area, also a large number of extremely fine crests 8, a number of which are formed between the crests 8 Since it has a very complicated appearance composed of the very fine valleys 9 and the many very fine valleys 10 (see FIG. 7) due to the penetration of the peaks 8, the sliding surface structure 4 Oil retention becomes extremely good.
The initial conformability of the slide surface construction 4 by preferential wearing of the tip side in Rokuryo metal crystals 7 ₁ is good.

Furthermore with the uniform finer Rokuryo metal crystals _71, while avoiding the high local surface pressurization can achieve fine differentiation sliding load, thereby slide surface construction 4
Exhibits excellent wear resistance not only under lubrication but also under non-lubrication.

As shown in FIG. 8, the inclination of the (hhh) plane with respect to the virtual plane 11 along the sliding surface 4a is six-edge metal crystal 7 _1.
This affects the oil retention, initial conformability, and wear resistance of the sliding surface structure 4. Therefore, the inclination angle θ formed by the (hhh) plane with respect to the virtual plane 11 is set to 0 ° ≦ θ ≦ 15 °. In this case, (hhh)
The inclination direction of the surface is not limited. The inclination angle θ is θ>
When the angle is 15 °, the oil retaining property, initial conformability, and abrasion resistance of the sliding surface structure 4 decrease.

(Hhh) The abundance S of the oriented metal crystal is
If for example, 40% ≦ S <90%, the sliding surface 4a is formed from an aggregate of Rokuryo metal crystals ₇₁ and Sanryo metal crystals 7 _2. The sliding characteristics of the sliding surface structure 4 are as follows.
becomes lower than the case where a substantially the entire formed from Rokuryo metal crystals 7 _1.

[0023] In the forming method, the minimum current density CD
min to CDmin ≧ 0.2 A / dm ² and the time ratio T _ON /
T _c to T _ON / T _c ≦ 0.35, and the average current density C
When Dm is set to CDm ≧ 3.5 A / dm ² ,
As shown in FIG. 9, can be each inclined surface 12 is substantially precipitate flat Rokuryo metal crystals 7 _1.

[0024] Since this Rokuryo metal crystals 7 ₁ has a high hardness,
This is effective in improving the wear resistance of the sliding surface structure 4.

[0025] In addition, CDmin ≦ the minimum current density CDmin
−0.2 A / dm ² and the time ratio T _ON / T _c to T _ON / T
_c ≦ 0.35, and further, the average current density CDm is set to CDm ≧
As each set to 3.5A / dm ^2, as shown in FIG. 10, it is possible to precipitate Rokuryo metal crystals 7 ₁ having a relatively deep valley 13 between Aitonaru ridge 6.

[0026] The Rokuryo metal crystals 7 _1, since the oil retention due to its valley 13 is good, it is effective in improving the seizure resistance of the slide surface construction 4.

As the metal crystal having the bcc structure, F
e, Cr, Mo, W, Ta, Zr, Nb, V, etc., or a crystal of a simple substance or alloy.

As the plating method, in addition to the electroplating method,
For example, a vapor deposition method such as a PVD method, a CVD method, a sputtering method, or ion plating can be used.
When performing W and Mo plating by sputtering, for example, the Ar pressure is 0.2 to 1 Pa, the base material temperature is 150 to 300 ° C., and the average Ar acceleration power (energy source) is 1 to 1.5 kW.
To control. When performing W plating by the CVD method, for example, the flow rate of WF ₆ (raw material) is 2 to 15 cc / min, the pressure in the chamber is 50 to 300 Pa, the base material temperature is 100 to 400 ° C., and the average output of the ArF maxima laser (energy source) is used. Is controlled to 5 to 40 W.

[0029] Example 1 Al alloy base material 2 land portion 3 ₁ and the skirt portion 3 ₂ outer circumferential surface, by applying an electrical Fe plating having a thickness of 15μm, which is composed of an aggregate of Fe crystals A plurality of pistons 1 for an internal combustion engine were manufactured by forming the sliding surface structure 4, and the following various considerations were made on the sliding surface structure 4.

A. Table 1 for the time ratio T _ON / T _c shows a plating bath conditions in Example 1～24,50～54 of the slide surface construction 4.

[0031]

[Table 1] Table 2 shows the plating conditions of Examples 1 to 14. In this case, in Examples 1 to 6, CDm = 7 A / dm ² , and in Examples 7-1.
4, the CDm is set to 4A / dm ² and each CD
T _ON / T _c was changed while m was constant.

[0032]

[Table 2] Table 3 shows the plating conditions of Examples 15 to 24. In this case, CDm was set to 3.5 A / dm ² in Examples 15 to 19, and CDm was set to 3 A / dm ² in Examples 20 to 24, and T _ON / T _c was changed at a constant CDm.

[0033]

[Table 3] Table 4 shows the plating conditions of Examples 50 to 54. In this case, T _ON / T _c was changed at a constant CDm = 2.5 A / dm ² .

[0034]

[Table 4] Tables 5 to 9 show the sliding surfaces 4 in Examples 1 to 24 and 50 to 54.
The crystal morphology a, the area ratio A of the six-edge Fe crystal and the average particle diameter d, the abundance S of each oriented Fe crystal, and the hardness are shown.

[0035]

[Table 5]

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

[Table 8]

[0039]

[Table 9] The area ratio A of the six-edge Fe crystal is as follows: when the area of the sliding surface 4a is B and the area occupied by all six-edge Fe crystals on the sliding surface 4a is C, A = (C / B) × 100 ( %). The grain size of the six-edge Fe crystal is a distance between both corners facing each other across the vertex, that is, an average value of three distances.

The abundance S is expressed by X in Examples 1 to 24 and 50 to 54.
It is obtained by the following method based on a line diffraction diagram (the X-ray irradiation direction is a direction perpendicular to the sliding surface 4a). Describing Example 8 as an example, FIG. 11 is an X-ray diffraction diagram of Example 8, and the abundance S of each oriented Fe crystal was obtained from the following equation. Note that, for example, {110} orientation F
The e crystal means an oriented Fe crystal with the {110} plane facing the sliding surface 4a. {110} oriented Fe crystal: S ₁₁₀ = {(I ₁₁₀ / IA)
₁₁₀ ) / T} × 100, {200} oriented Fe crystal: S ₂₀₀ = {(I ₂₀₀ / IA)
₂₀₀ ) / T} × 100, {211} oriented Fe crystal: S ₂₁₁ = {(I ₂₁₁ / IA)
₂₁₁ ) / T} × 100, {310} oriented Fe crystal: S ₃₁₀ = {(I ₃₁₀ / IA)
₃₁₀ ) / T} × 100, {222} oriented Fe crystal: S ₂₂₂ = {(I ₂₂₂ / IA)
₂₂₂ ) / T｝ × 100 where I ₁₁₀ , I ₂₀₀ , I ₂₁₁ , I ₃₁₀ , and I ₂₂₂ are the measured values (cps) of the X-ray reflection intensity of each crystal plane, and I ₁₁₀ =
0.8K, I ₂₀₀ = 0.4K, I ₂₁₁ = 1.7K, I
₃₁₀ = 0.15K, a I ₂₂₂ = 9.8K. Also IA
₁₁₀ , IA ₂₀₀ , IA ₂₁₁ , IA ₃₁₀ , IA ₂₂₂ are AS
The ratio of the X-ray reflection intensity of each crystal plane in the TM card, IA
₁₁₀ = 100, IA ₂₀₀ = 20, IA ₂₁₁ = 30, IA
₃₁₀ = 12 and IA ₂₂₂ = 6. Further, T is T =
(I ₁₁₀ / IA ₁₁₀ ) + (I ₂₀₀ / IA ₂₀₀ ) + (I
_{211 / IA 211) + (I} 310 / IA 310) + (I 222 /
IA ₂₂₂₎ is a = 1.73K.

FIG. 12 is an electron micrograph showing the crystal structure of the sliding surface 4a in Example 8, where a large number of hexagonal pyramidal hexagonal Fe crystals are observed. As shown in Table 6, the area ratio A of the six-edge Fe crystal is A = 96%, and the average particle size d is d = 3.
μm. The six-edge Fe crystal is a (222) oriented Fe crystal in which the (hhh) plane, that is, the {222} plane faces the sliding surface 4a. In this case, {222} oriented Fe
As shown in Table 6 and FIG.
4.3%.

FIG. 13 is an X-ray diffraction diagram of Example 14. FIG.
4 is an electron micrograph showing the crystal structure of the sliding surface 4a in Example 14, where a large number of granular Fe crystals are observed.

FIG. 15 shows the relationship between the time ratio T _ON / T _c and the abundance S of {222} oriented Fe crystals in Examples 1 to 24 and 50 to 54. In the figure, points (1) to (1) 24), (5
0) to (54) correspond to Examples 1 to 24 and 50 to 54, respectively. As is apparent from FIG. 15, the time ratio T _ON / T
_By setting _c to T _ON / T _c ≦ 0.45, the abundance S of {222} oriented Fe crystals can be set to S ≧ 40% at each average current density CDm.

In this case, the average current density Dm is set to Dm ≧ 3.
5 A / dm ² and the time rate T _ON / T _c is T _ON / T _c ≦
When each is set to 0.35, {222} oriented Fe
The existence ratio S of the crystal becomes S ≧ 90%, and in FIG.
90% ≦ S ≦ 100% and 0 <T _ON / T _c ≦ 0.3
In region 5, most of the {222} oriented Fe crystal takes the form of a six-edge Fe crystal.

On the other hand, in FIG. 15, the region where S ≧ 40% and T _ON / T _c ≦ 0.45 except for the single region of the six-edge Fe crystal is a six-edge Fe crystal and a three-edge Fe crystal. This is a mixed region of crystals.

B. Fe ion concentration Fe ²⁺ Table 10 for the plating bath, indicating the plating bath conditions in Examples 25 to 36 of the slide surface construction 4.

[0047]

[Table 10] Table 11 shows the plating conditions of Examples 25 to 36. In this case, in Examples 25 to 27, CDm = 7 A / dm ² and in Example 28
CDm = 4 A / dm ² for ~ 31, C for Examples 32-34
Dm = 3.5 A / dm ² , and in Examples 35 and 36, CDm
= 3 A / dm ² , and the Fe ion concentration Fe ²⁺ was changed as shown in Table 10 while each CDm was constant.

[0048]

[Table 11] Tables 12 and 13 show the crystal morphology of the sliding surface 4a, the area ratio A of the six-edge Fe crystal and the average grain size d, the abundance S of each oriented Fe crystal, and the hardness in Examples 25 to 36, respectively.

[0049]

[Table 12]

[0050]

[Table 13] FIG. 16 shows Examples 25 to 36 and Examples 2, 8, 16, and 2 described above.
1. Fe ion concentration of plating bath Fe ²⁺ and Δ22
The relationship with the abundance S of 2｝ -oriented Fe crystals is shown in FIG.
Points (2), (8), (16), (21), (25)-
(36) corresponds to Examples 2, 8, 16, 21, 25 to 36, respectively. As is clear from FIG. 16, for example, when the average current density CDm ≧ 3 A / dm ² , the Fe ion concentration Fe
By setting ²⁺ to Fe ²⁺ ≧ 0.6, the abundance S of {222} -oriented Fe crystals can be set to S ≧ 40%. Also, the existence ratio S of the {222} oriented Fe crystal is S ≧ 9.
To achieve 0%, the average current density CDm ≧ 3.5 A /
At dm ² , it is necessary to set the Fe ion concentration Fe ^{2+ so} that Fe ²⁺ ≧ 1.

C. About pH of plating bath Table 14 shows the plating bath conditions in Examples 37 to 47 of the sliding surface structure 4.

[0052]

[Table 14] Table 15 shows the plating conditions of Examples 37 to 47. In this case, CDm = 7 A / dm ² in Examples 37 to 39, and Example 40
~ 42, CDm = 4A / dm ² , and in Examples 43-45, Cm
Dm = 3.5 A / dm ² , and in Examples 46 and 47, CDm = 3
Each is set to A / dm ^2, in each CDm constant,
The pH was varied as shown in Table 14.

[0053]

[Table 15] Tables 16 and 17 show the crystal morphology of the sliding surface 4a, the area ratio A of the six-edge Fe crystal and the average particle diameter d, the abundance S of each oriented Fe crystal, and the hardness in Examples 37 to 47, respectively.

[0054]

[Table 16]

[0055]

[Table 17] FIG. 17 shows Examples 37 to 47 and Examples 2, 8, 16, and 2 described above.
1 shows the relationship between the pH of the plating bath and the abundance S of the {222} oriented Fe crystals, and points (2), (8),
(16), (21), (37) to (47) are Examples 2, 8,
16, 21, and 37 to 47, respectively. As is clear from FIG. 17, for example, the average current density CDm ≧ 3 A /
By setting the pH at dm ² to pH ≧ 4.5, the abundance S of {222} oriented Fe crystals can be set to S ≧ 40%. Further, in order to make the abundance S of {222} oriented Fe crystals S ≧ 90%, the average current density CDm
It is necessary to set the pH to pH ≧ 5.5 at ≧ 3.5 A / dm ² .

D. Regarding seizure resistance and abrasion resistance Examples of the sliding surface structure 4 1,7,8,11-14,17,2
A burn-in test was performed on chips 2 to 24 and 31 by a chip-on-disk method under lubrication to obtain {222} orientation F
The relationship between the e crystal abundance S and the seizure load was determined.
The test conditions are as follows. Disc material Al-1
0% by weight Si alloy, disk rotation speed 15m / sec,
The amount of lubrication is 0.3 ml / min. The area of the sliding surface of the chip manufactured from the sliding surface structure is 1 cm ² .

In each of the examples 1, 7, 8, 11 to 14, 1
With respect to 7,22 to 24,31, a wear test was performed by a chip-on-disk method without lubrication, and the relationship between the abundance S of {222} oriented Fe crystals and the wear amount of the chip was determined. The test conditions are as follows. Disc material Al-10 wt% Si alloy, disc rotation speed
0.5m / sec, load 100N, sliding distance 1km, sliding surface area 1cm of chip manufactured from sliding surface structure
² . The amount of wear is the weight loss (mg) per 1 cm ² of the chip area.

Table 18 shows the seizure test and wear test results. 18 and 19 are graphs of Table 18, in which points (1), (7), (8), (11) to
(14), (17), (22) to (24) and (31) correspond to Examples 1, 7, 8, 11 to 14, 17, 22 to 24 and 31, respectively.

[0059]

[Table 18] As is clear from Table 18 and FIG. 18, when the abundance S of the {222} -oriented Fe crystals is S ≧ 40%, the oil retaining property and the initial conformability of the sliding surface 4a are improved, so that the seizure resistance is significantly reduced. improves. In particular, when the abundance S of the {222} oriented Fe crystal is S ≧ 90%, it is clear that the seizure resistance is dramatically improved due to the increase in the density of the six-edge Fe crystal.

As is clear from Table 18 and FIG.
When the abundance S of the {222} -oriented Fe crystal is S ≧ 40%, the wear amount is small, so that good wear resistance can be obtained even without lubrication. In particular, {222} oriented Fe
When the crystal abundance S ≧ 90%, the wear resistance becomes extremely good due to the high density of the six-edge Fe crystal.

[0061] In Example 2 Example 1 has been set the minimum current density CDmin to CDmin = 0A / dm ^2, in this embodiment, whether CDmin ≧ 0.2 A / dm ^2, or CDmin ≦ - It is set to 0.2 A / dm ² .

Table 19 shows the plating bath conditions in Examples 1 to 7 of the sliding surface structure 4. Example 4 corresponds to Example 8 of Example 1.
Is the same as

[0063]

[Table 19] Table 20 shows the plating conditions of Examples 1 to 7.

[0064]

[Table 20] Table 21 shows the crystal morphology of the sliding surface 4a in Examples 1 to 7, the area ratio A of the six-edge Fe crystal, the average particle diameter d, and the orientation Fe
The abundance S of crystal and hardness are shown.

[0065]

[Table 21] FIG. 20 is an X-ray diffraction diagram of Example 1, and FIG. 21 is an electron micrograph showing the crystal structure of the sliding surface 4a in Example 1. As is clear from FIG. 21, the minimum current density CDmin
Is set to CDmin ≦ −0.2 A / dm ² , then ｛22
The 2｝ -oriented Fe crystal is a six-edge Fe crystal having a relatively deep valley between adjacent ridge lines.

FIG. 22 is an X-ray diffraction diagram of Example 7, and FIG. 23 is an electron micrograph showing the crystal structure of the sliding surface 4a in Example 7. As is apparent from FIG. 23, when the minimum current density CDmin is set to CDmin ≧ 0.2 A / dm ² , the {222} oriented Fe crystal becomes a six-ridged Fe crystal in which each slope is substantially flat.

For Examples 1 to 7, under the same conditions as described above,
When a seizure test under lubrication and a wear test under no lubrication were performed, the results shown in Table 22 were obtained. FIGS. 24 and 25 are graphs of Table 22, in which points (1) to (1) are shown.
(7) corresponds to Examples 1 to 7, respectively.

[0068]

[Table 22] As is clear from Table 22 and FIG. 24, the minimum current density CD
When min is set to CDmin ≦ −0.2 A / dm ² , the oil retention becomes good due to each valley of each hexagonal Fe crystal, so that the seizure resistance is improved as in Examples 1 to 3.

As is clear from Table 22 and FIG.
When the minimum current density CDmin is set to CDmin ≧ 0.2 A / dm ² , the hardness of each hexagonal Fe crystal becomes high.
As described above, the wear resistance is good.

As shown in FIG. 26, sliding surface structure 4 may be formed of an aggregate of metal crystals having a face-centered cubic structure (fcc structure). The aggregate includes a (3hhh) oriented metal crystal having a columnar growth from the base material 2 and a (3hhh) plane directed toward the sliding surface 4a with a Miller index.
hh) The abundance S of the oriented metal crystal is set to S ≧ 40%. As shown in FIG. 27, (3hhh)
The crystal is a quadrangular pyramid (or truncated pyramid) on the sliding surface 4a
The metal forming crystals, i.e. a four ridge metal crystals 7 ₃ having four ridge lines 6.

As shown in FIG. 28, the inclination of the (3hhh) plane with respect to the imaginary plane 11 along the sliding surface 4a appears as the inclination of a quadrangular pyramid. Affect. Therefore, the inclination angle θ formed by the (3hhh) plane with respect to the virtual plane 11 is set to 0 ° ≦ θ ≦ 15 ° for the same reason as described above. in this case,
(3hhh) The direction of inclination of the plane is not limited.

As the metal crystal having the fcc structure, P
b, Ni, Cu, Pt, Al, Ag, Au and the like, or a crystal of a simple substance or alloy.

Hereinafter, a specific example will be described.

A camshaft for an internal combustion engine was manufactured by applying an electric Ni plating process to the outer peripheral surface of a journal portion of a cast iron base material to form a sliding surface structure composed of an aggregate of Ni crystals.

The plating bath conditions were as follows: nickel sulfate concentration 3
00 g / liter, Ni ion concentration Ni ²⁺ = 1 mol / liter, pH = 5.5, temperature 55 ° C. The plating conditions were as follows: minimum current density CDmin = 0 A / dm ² , maximum current density CDmax = 20 A / dm ² , average current density CD
m = 4 A / dm ² , time ratio T _ON / T _c = 0.2, and output time T _ON = 2 msec.

The crystal form of the sliding surface is a mixture of quadrangular pyramids and grains.
Area ratio of four-edge Ni crystal A = 60%, average particle size d = 4
μm, the abundance S of each oriented Ni crystal is {111} oriented Ni crystal S = 29%, {200} oriented Ni crystal
S = 15.2%, {220} oriented Ni crystal S = 4.
7%, {311} oriented Ni crystal S = 51.1%, and hardness is Hv = 250.

The abundance S is an X-ray diffraction diagram of the sliding surface structure shown in FIG. 29 (the X-ray irradiation direction is perpendicular to the sliding surface).
Is obtained from the following equation based on Note that, for example, a {111} oriented Ni crystal means an oriented Ni crystal with the {111} plane facing the sliding surface side. {111} oriented Ni crystal: S ₁₁₁ = {(I ₁₁₁ / IA)
₁₁₁ ) / T} × 100, {200} oriented Ni crystal: S ₂₀₀ = {(I ₂₀₀ / IA)
₂₀₀ ) / T} × 100, {220} oriented Ni crystal: S ₂₂₀ = {(I ₂₂₀ / IA)
₂₂₀ ) / T} × 100, {311} oriented Ni crystal: S ₃₁₁ = {(I ₃₁₁ / IA)
₃₁₁ ) / T｝ × 100 where I ₁₁₁ , I ₂₀₀ , I ₂₂₀ and I ₃₁₁ are the measured values (cps) of the X-ray reflection intensity of each crystal plane, and I ₁₁₁ = 78.6.
K, I ₂₀₀ = 17.4K, I ₂₂₀ = 2.7K, I ₃₁₁ =
27.7. IA ₁₁₀ , IA ₂₀₀ , IA ₂₂₀ ,
IA ₃₁₁ is an X-ray reflection intensity ratio of each crystal plane in the ASTM card, IA ₁₁₁ = 100, IA ₂₀₀ = 42, IA
₂₂₀ = 21, IA ₃₁₁ = 20. Further, T is T =
(I ₁₁₁ / IA ₁₁₁ ) + (I ₂₀₀ / IA ₂₀₀ ) + (I
_{220 / IA 220) + (I} 311 / IA 311) = 2.71K
It is.

FIG. 30 is a micrograph showing the crystal structure of the sliding surface. In FIG. 30, a large number of quadrangular pyramid-shaped four-edge Ni crystals are observed. This four-edge Ni crystal is (3hh
h) A {311} oriented Ni crystal with the {311} plane facing the sliding surface side, and its abundance S is S =
51.1%.

The sliding surface structure was subjected to a seizure test under lubrication and a wear test without lubrication under the same conditions as described above. The seizure load was 650 N, and the wear amount was 1.6 mg. Met.

The sliding surface structure is applied to, for example, the following sliding parts of internal combustion engine parts and the like. Piston (ring groove), piston ring, piston pin, connecting rod, crankshaft, bearing metal, oil pump rotor, oil pump rotor housing, camshaft, spring (end face), spring seat, spring retainer,
Cotta, rocker arm, roller bearing outer case, roller bearing inner case, valve stem, valve face, hydraulic tappet, water pump rotor shaft, pulley, gear, transmission shaft, clutch plate, washer, bolt (seat surface, screw).

The present invention is not limited to the formation of the sliding surface structure, but also includes the formation of a light absorber using the high absorbance of the film having the metal crystal and the use of the magnetic shield material utilizing the high magnetic permeability of the film. Applied to formation, etc.

[0082]

According to the present invention, the output of the plating energy source is controlled so as to draw a pulse waveform as described above, and the ratio T _ON / T _c of the output time T _ON and the cycle time T _c is set to the above-mentioned value. Has many pyramid-shaped metal crystals and / or truncated pyramid-shaped metal crystals that have been made finer and more uniform in particle size by being specified as such, and can be applied to various uses such as a sliding surface structure. Metal film can be easily formed.

[Brief description of the drawings]

FIG. 1 is a side view of a piston.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a perspective view showing a body-centered cubic structure and its (hhh) plane.

FIG. 4 is an output waveform diagram of a power supply for electroplating.

FIG. 5 is a main part plan view showing an example of a sliding surface structure.

FIG. 6 is a plan view of a three-edge metal crystal.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 5;

FIG. 8 is an explanatory diagram showing an inclination of a (hhh) plane in a body-centered cubic structure.

FIG. 9 is a perspective view showing an example of a six-edge metal crystal.

FIG. 10 is a perspective view showing another example of a six-edge metal crystal.

FIG. 11 is an X-ray diffraction diagram of a first example of the sliding surface structure.

FIG. 12 is a micrograph showing a crystal structure of a sliding surface in a first example of a sliding surface structure.

FIG. 13 is an X-ray diffraction diagram of a second example of the sliding surface structure.

FIG. 14 is a micrograph showing a crystal structure of a sliding surface in a second example of the sliding surface structure.

FIG. 15 is a graph showing the relationship between the time ratio T _ON / T _c and the abundance S of {222} oriented Fe crystals.

FIG. 16: Fe ion concentration of plating bath Fe ²⁺ and Δ22
It is a graph which shows the relationship with the abundance S of 2 degree orientation Fe crystal.

FIG. 17 is a graph showing a relationship between the pH of a plating bath and the abundance S of {222} oriented Fe crystals.

FIG. 18 is a graph showing the relationship between the abundance S of {222} oriented Fe crystals and the seizure load.

FIG. 19 is a graph showing the relationship between the abundance S of {222} oriented Fe crystals and the amount of wear.

FIG. 20 is an X-ray diffraction diagram of a third example of the sliding surface structure.

FIG. 21 is a micrograph showing a crystal structure of a sliding surface in a third example of the sliding surface structure.

FIG. 22 is an X-ray diffraction diagram of a fourth example of the sliding surface structure.

FIG. 23 is a micrograph showing a crystal structure of a sliding surface in a fourth example of the sliding surface structure.

FIG. 24 is a graph showing the relationship between the minimum current density CDmin and the seizure load.

FIG. 25 is a graph showing the relationship between the minimum current density CDmin and the amount of wear.

FIG. 26 is a perspective view showing a face-centered cubic structure and its (3hhh) plane.

FIG. 27 is a plan view of a four-edge metal crystal.

FIG. 28 is an explanatory diagram showing the inclination of the (3hhh) plane in the face-centered cubic structure.

FIG. 29 is an X-ray diffraction diagram of a fifth example of the sliding surface structure.

FIG. 30 is a micrograph showing a crystal structure of a sliding surface in a fifth example of the sliding surface structure.

[Description of Signs] 4 Sliding surface structure (metal film) 4a Sliding surface (surface) 7 ₁ Six-edge metal crystal (pyramidal metal crystal)

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenji Dosaka 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda R & D Co., Ltd. (56) References JP-A-60-152694 (JP, A) JP-A Heihei 5-25683 (JP, A) JP-A-5-25688 (JP, A) JP-A-60-149768 (JP, A)

Claims (5)

(57) [Claims] An output of an energy source for plating when forming a metal film having at least one of a large number of pyramid-shaped metal crystals or truncated pyramid-shaped metal crystals on a surface by a plating method.
The maximum value I and I, the output I from the minimum value Imin I rising
max , then control so as to draw a pulse waveform as falling to the minimum value Imin , the output time from the start of the rise of the output I to the start of the fall is T _ON, and from the start of the previous rise to the next Assuming that one cycle is from the start of the rise to the cycle time _Tc , the output time T _ON
The ratio T _ON / T _c between the cycle time T _c and T _ON / T _c ≦
A method for forming a metal film, wherein the method is set to 0.45. 2. The ratio T _ON / T _c is _defined as T _ON / T _c ≦ 0.3.
The method for forming a metal film according to claim 1, wherein the value is set to 5. 3. The method for forming a metal film according to claim 1, wherein the plating method is an electroplating method, and the average current density CDm is set so that CDm ≧ 3.5 A / dm ² . 4. CDmin ≧ 0 the minimum current density CDmin.
The method for forming a metal film according to claim 3, wherein the method is set to 2 A / dm ² . 5. CDmin ≦ the minimum current density CDmin -
Set to 0.2 A / dm ^2, the method of forming the metal coating of claim 3 wherein.