JP3023530B2 - Method for manufacturing sliding member of vehicle suspension having titanium oxide coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to Ri by the ion plating method, the wear resistance is excellent in low friction resistance or the like, the sliding portion of the suspension for a vehicle having a titanium oxide film excellent in design property The present invention relates to a method for manufacturing a material .

[0002]

2. Description of the Related Art Conventionally, the surface of a sliding member of a vehicle suspension, for example, an inner tube used for a front fork of a motorcycle or a bicycle, is subjected to hard chrome plating in order to improve slidability and corrosion resistance. Was a common surface treatment method. Further, as a special case, there is a case in which a titanium nitride coating exhibiting a golden color is applied by an ion plating method.

[0003]

However, the sliding member of the vehicle suspension such as the inner tube has a part of its outer surface exposed to the outside, and the conventional hard chrome plated surface has a silver-white metal. The gloss was limited and the design was poor. Further, those coated with titanium nitride by the ion plating method are excellent in wear resistance, low friction resistance, etc., and exhibit a gold color to enhance the design, but the color tone is limited to gold.

Accordingly, the present invention provides a titanium oxide film having excellent various properties such that a brown or dark blue color can be added and high decorativeness can be imparted while maintaining high hardness and abrasion resistance. the aims to provide a method for producing a sliding member of the vehicle suspension having on its outer peripheral sliding surface.

[0005]

In order to solve the above-mentioned problems, a method of manufacturing a sliding member for a vehicle suspension having a titanium oxide film according to the present invention is disclosed.
On the outer peripheral sliding surface of the sliding member made of titanium oxide by ion plating, a brown-based film having a thickness of 0.5 to 10 μm was used.
Or a titanium oxide film that forms a wear-resistant layer of dark blue color
Manufacturing method of a sliding member of a vehicle suspension having
The ion plating method uses an HCD type ion
Using a plating apparatus, the beam output of the apparatus was 3
Oxygen gas of 100 to 500 A and in the vacuum chamber of the apparatus
And this <br/> for controlling the partial pressure in the range of ^{5 × 10 -5 ~1 × 10 -4} Torr, a is characterized.

[0006] The sliding member 2 of the vehicle suspension having a titanium oxide film in a specific description of the invention The invention, as shown in sectional view in FIG. 1, a cylindrical outer peripheral sliding of the base material 4 of the sliding member The moving surface has a colored (brown or dark blue) wear-resistant layer 6 made of titanium oxide, and the titanium oxide film 6 is formed by an ion plating method. Reference numeral 8 is an undercoat layer made of titanium similarly formed by the ion plating method. The sliding members of the vehicle suspension include the inner tube of the front fork of a motorcycle, the piston rod of the rear suspension, the inner tube of the front fork of a bicycle,
There are inner tubes for automobile shock absorbers and the like.

[0007] The ion plating method is a vacuum deposition method utilizing a phenomenon in which a vaporized metal ionized by discharge and a reactive gas are coated as a metal or ceramic film while repeatedly applying an appropriate impact to a negatively applied base material. It is characterized by the fact that the evaporating substance is electrically active and is given an energy by an electric field, so that it is very easy to turn around and has excellent adhesion.

The thickness of the titanium oxide film 6 formed on the surface of the base material 4 of the sliding member by such an ion plating method is desirably 0.5 to 10 μm, preferably 1 to 3 μm. If the film thickness is less than 0.5 μm, it will not last long due to wear, while the upper limit is not particularly limited,
The thicker the film, the longer the processing time and the higher the cost. If the thickness is extremely large (several tens of μm or more), the film is easily peeled off by impact. The range of 1 to 3 μm is a practical range having sufficient abrasion resistance and advantageous in terms of cost. In addition, as the material of the base material 4 of the sliding member of the vehicle suspension, structural alloy steel is particularly common because of its excellent toughness. Alternatively, the structural alloy steel may be subjected to hard chrome plating.

The titanium oxide film according to the present invention exhibits a color (brown, navy). A desired color can be obtained by appropriately controlling the processing conditions by the ion plating method, in particular, the amount of oxygen gas introduced into the vacuum chamber of the ion plating apparatus and the beam output. The introduction amount of oxygen gas is adjusted according to the beam output (300 to 500 A), and the partial pressure of oxygen gas in the vacuum chamber is 5 × 10 ⁻⁵ to 1 × 10 ⁻⁴ Torr.
Is controlled so as to fall within the range. The trend in this case is
When the beam output is small, the amount of Ti gas evaporated is also small, so the amount of oxygen gas introduced is also reduced.
The amount of oxygen gas introduced is increased since the amount of evaporation of i also increases. It is estimated that the higher the beam output, the higher the reactivity. Therefore, even if the oxygen gas introduction amount is increased, the oxygen gas consumption is increased, and the oxygen gas partial pressure in the vacuum chamber may be reduced. It is to be noted that a higher beam output is advantageous in that a short processing time is required to form a film having the same thickness. When the beam output is less than 300 A, the processing takes a long time and the productivity is reduced. On the other hand, when the beam output exceeds 500 A, the hearth temperature becomes too high and the hearth may be damaged.

Specifically, in order to obtain a light brown to dark brown color, for example, when the beam output is 450 A, the oxygen gas partial pressure is set to 5.6 × 10 ^{−5 to} 6.5 ×. 10 ^-5 To
Control to rr. When the beam output is 300 A, the partial pressure of oxygen gas is controlled at 5.9 × 10 ^{−5 to} 6.2 × 10 ⁻⁵ Torr. At the initial stage of oxygen gas introduction, the color tone is yellow, red,
It sequentially changes to blue, changes again to yellow, red, blue,
This is repeated several times, but as the film thickness increases, the color tone gradually becomes turbid and exhibits a brownish color tone. Thereafter, even when the film thickness increases, the color tone becomes constant. In order to obtain a navy blue color tone of light navy blue to purple navy blue, when the beam output is 450 A, the oxygen gas partial pressure is set to 7 × 10 ^{−5 to} 9.8.
Control to × 10 ^-5 Torr. When the beam output is 300 A, the oxygen gas partial pressure is increased from 6.4 × 10 ^{−5 to} 6.5 × 10 ⁻⁵
Control to rr. As in the case of the brown type, in the initial stage of the introduction of the oxygen gas, the color tone sequentially changes to yellow, red, and blue, and again changes to yellow, red, and blue, and this is repeated several times. As the size increases, the color tone gradually becomes muddy, giving a dark blue color tone, and thereafter, the color tone becomes constant even when the film thickness increases. By appropriately selecting a partial pressure within the above oxygen gas partial pressure range, a desired color tone can be obtained from light brown to dark brown in a brownish color and from light navy blue to a navy blue in a navy blue color.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. HCD (Hollow Cathode) used in the present invention
FIG. 2 shows an outline of a discharge type ion plating apparatus 10. In FIG. 2, a work 14 to be coated is disposed in a vacuum chamber 12, and a water-cooled copper hearth 18 below which receives a Ti raw material 16 which is a metal to be evaporated is provided.
Is arranged. A hollow cathode type electron gun (hollow cathode) for melting and evaporating the Ti raw material 16 directly above the hearth 18
20 is provided, to which an Ar gas introduction pipe 22 is connected. Between the hearth 18 and the hollow cathode 20,
A focusing coil 23 for focusing an electron beam and irradiating the Ti raw material 16 is arranged. Reference numeral 24 denotes an introduction tube for introducing the reaction gas O ₂ , reference numeral 26 denotes a DC bias power supply for applying a bias voltage to the work 14, and reference numeral 28 denotes a DC with superimposed high frequency between the hollow cathode 20 and the hearth 18. A DC power supply 30 is an exhaust port. In the vacuum chamber 12, a heater 32 is provided at an appropriate position for heating the work 14, and the work 14 and the hollow cathode type electron gun 20 are provided.
Is provided between them.

An example of the step of coating the outer peripheral sliding surface of the inner tube with a titanium oxide film using the above-described apparatus will be described. First, a pretreatment for removing dirt and grease from the base material of the inner tube made of structural alloy steel subjected to hard chromium plating as a work and removing an oxide film on the outer peripheral surface is performed. 14 is attached to a jig (not shown) in the vacuum chamber 12,
To charge.

When the preparation is completed, the vacuum chamber 1
5 × 10 ⁻⁶ while heating the inside of the furnace 2 to 350 ° C. or higher (about 350 to 500 ° C., or higher if the temperature is not dull depending on the material of the work).
The pressure is reduced to a pressure of about Torr or less, and is maintained for a predetermined time (about 30 to 60 minutes) after the work reaches a predetermined temperature. Next, high-purity argon gas is introduced into the vacuum chamber 12,
At a pressure of about 3.5 × 10 ⁻⁴ Torr, 75
A negative voltage of about 0 V is applied to clean the work surface by ion bombardment.

Next, argon gas is introduced into the hollow cathode 20 made of Ta and ignited (current is about 300 A). After the titanium 16 in the hearth 18 below the hollow cathode 20 is dissolved and the titanium is evaporated and stabilized, the current is increased to about 450A. By holding for a certain time (about 3 to 5 minutes), impurities such as oxides on the surface of the titanium 16 in the hearth are removed and removed. In the processing steps so far, the shutter 34 between the hearth 18 and the work 14 is closed in order to prevent impurities from being deposited on the work 14. Note that the numerical values such as the temperature, pressure, voltage, current value, and the like described above are merely examples, and are not limited to the above numerical values.

Next, the shutter 34 is opened, and first, only titanium is evaporated, and only titanium is undercoated on the work 14 to improve the adhesion. The thickness of the undercoat layer is preferably about 0.05 to 0.2 μm from the viewpoint of improving the adhesion. After undercoating titanium for an arbitrary time (about 2 to 5 minutes), oxygen gas is introduced from the reaction gas introduction pipe 24 to form a film made of titanium oxide. As a processing condition at this time, the partial pressure of argon gas was set to 8 × 10 ^−5.
Torr, focusing current of 0.8 V and 300 A, bias voltage of 60 V, heating temperature of 350 ° C., deposition time of 40 minutes, constant beam output and partial pressure of oxygen gas to be introduced, various adhesions of samples Table 1 shows the measurement results of the degree, hardness and film thickness. As a comparative example, a case where a gold titanium nitride film was formed by introducing nitrogen gas instead of introducing oxygen gas was also shown.

[0016]

[Table 1]

Here, in the adhesion test, the degree of adhesion was evaluated from the measurement of frictional force by the following scratch (scratch) test. That is, a scratch tester (scratch tester CSR012 manufactured by Resca Corporation) schematically shown in FIG.
0) Using 40, the radius of the diamond indenter 42: 0.2 mm
, Cone angle: 120 °, vertical load: 0-20 kgf, scratching distance: 10 mm, stage 44 that moves at a constant speed
A diamond indenter 42 that applies a load Fz (N) that linearly increases in a direction perpendicular to a sample 46 mounted thereon.
Is further translated at a constant speed to scratch (scratch) the sample 46. It was determined from the vertical load value Fz (N) when the frictional force generated in the scratch direction at this time suddenly increased. The hardness (Hv) is a value measured under a load of 5 g.

As can be seen from these results, the inner tube having the titanium oxide coating according to the above embodiment is
The hardness is almost the same as that of the titanium nitride film, and is about twice or more as high as 800 to 1000 / Hv of the conventional hard chromium plating, and has excellent wear resistance and good slidability. Further, the adhesion is said to be about 60 to 70 N in the case of the titanium nitride film formed by the conventional method. (The titanium nitride coating was comparable to that of the present example.) It is excellent in peel resistance and has a desired color and is extremely excellent in design.

In the above processing steps, it is desirable to adjust the thickness of the oxide film deposited on the work by rotating or moving the work to the left and right so as to be uniform in all portions. Also, if the amount of Ti scattered from the evaporation source is not constant depending on the state of the hearth, it is difficult to obtain a reproducible color tone, so the amount of Ti replenishment in the hearth is adjusted each time so that the amount of Ti scattered for each batch is constant. Is preferred.

[0020]

According to the present invention, a brown or dark blue color can be added and a high degree of decorativeness can be imparted while maintaining the high hardness and abrasion resistance of titanium oxide. method for producing a sliding member of a suspension for a vehicle having on its outer peripheral sliding surface of the titanium oxide film of properties makes the most excellent such may be capable of providing.

[Brief description of the drawings]

Sectional view of a sliding member of a vehicle suspension having a titanium oxide film in the present invention; FIG.

FIG. 2 is an explanatory view showing an ion plating apparatus used to carry out the present invention.

FIG. 3 is an explanatory view of an adhesion test method.

[Explanation of symbols]

2 Sliding member of vehicle suspension having titanium oxide coating 4 Base material of sliding member 6 Wear resistant layer 8 Undercoat layer 10 HCD type ion plating device 12 Vacuum tank 14 Work 16 Ti raw material 18 Hearth 20 Hollow cathode type Electron gun (hollow cathode) 22 Ar gas introduction tube 23 Focusing coil 24 Reaction gas introduction tube 26 DC bias power supply 28 DC power supply 30 Exhaust port 32 Heater 34 Shutter 40 Scratch tester 42 Diamond indenter 44 Constant speed moving stage 46 Sample

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 9/00-9/58 C22C 14/00 B62K 25/08 F16J 1/00-10/04

Claims (1)

(57) [Claims] An abrasion-resistant layer of titanium oxide having a thickness of 0.5 to 10 μm and a brownish or navy blue color is formed on an outer peripheral sliding surface of a sliding member of a vehicle suspension by an ion plating method. Vehicle suspension with titanium oxide coating
A method of manufacturing a sliding member of a pension, wherein the ion
The plating method is an HCD type ion plating device.
And the beam output of the device is 300-500A.
And the partial pressure of oxygen gas in the vacuum chamber of the apparatus is 5 × 10 ⁻⁵ to
A method for producing a sliding member for a vehicle suspension having a titanium oxide film, wherein the sliding member is controlled to a range of 1 × 10 ⁻⁴ Torr .