JP2005029878A - Hard chromium plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chromium plating method capable of forming a new granular chromium plated layer. <P>SOLUTION: In the method for obtaining a granular plated layer having suitable friction properties, the surface of the body in a metallic product is subjected to hard chromium plating using a chromium plating bath under the conditions of a current density in 60 to 1,800 A/dm<SP>2</SP>×a bath voltage in 4 to 30 V×a bath temperature in 25 to 55°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel hard chrome plating method and a hard chrome plated metal product.

  Non-Patent Document 1 describes the bath composition and plating conditions in the conventional hard chromium plating method as shown in Table 1.

ここで、上記条件において、浴電圧４〜８Ｖ、めっき時間は、所要膜厚により異なるが、通常の硬質クロムめっき膜厚１０〜３０μｍの場合、１〜３ｈであった。

Here, in the above conditions, the bath voltage was 4 to 8 V, and the plating time was 1 to 3 h in the case of a normal hard chromium plating film thickness of 10 to 30 μm, although it varied depending on the required film thickness.

  And most of the chromium plating layers formed with these bath compositions and plating conditions usually have good sliding properties.

See Chemical Chemistry Society of Japan, “Chemical Handbook, Application, 3rd revised edition” (Sho 55-3-15) Maruzen, p.

  In view of the above, an object of the present invention is to provide a chromium plating method capable of forming a novel granular chromium plating layer.

  In the process of studying chromium plating, the present inventors have performed plating under conditions selected from a certain range that deviates significantly from known plating conditions in a conventional general-purpose bath composition. Granular plating that has slip resistance (a certain amount of frictional resistance) in the particle size range, and intermediate level slip properties in other particle size ranges and equivalent or better slip properties than in conventional general-purpose plating baths Furthermore, the inventors have found that the plating time can be shortened as compared with the prior art, and arrived at the present invention having the following configuration.

One of the present invention uses a chromium plating bath (excluding a fluorination bath) on a metal product body, a current density of 60 to 1800 A / dm ² , a bath voltage of 4 to 30 V, and a bath temperature of 25 to 55 ° C. In the method of hard chrome plating, the chrome plating is performed under the following conditions.

  The chromium plating bath is usually a sergeant bath.

Another aspect of the present invention is that a chromium plating bath is used on a metal product body, and chromium plating is performed under conditions of a current density of more than 150, 1800 A / dm ² , a bath voltage of 4-30 V, and a bath temperature of 25-55 ° C. It is characterized by doing.

  In each of the above configurations, the plating time is usually 2 to 100 min.

  Moreover, the hard chromium plating product of this invention is equipped with the granular chromium plating layer by a chromium plating bath (except a silicofluorination bath) on the surface of a metal product main body, and this granular plating layer is normally 5-200 micrometers in average particle diameter. The film thickness is 8 to 350 μm.

  Another hard chrome plated product of the present invention includes a granular chrome plated layer formed by a fluorination bath on the surface of a metal product main body, the granular plated layer having an average particle size of more than 30 μm and 250 μm or less. The thickness is more than 40 μm and 350 μm or less.

In each of the above configurations, the coefficient of static friction is desirable from the viewpoint of clampability, from 0.17 or more, to 0.14 to less than 0.17 having an intermediate slippage less than that, and further to slipperiness. Hard chrome plated products that are less than 0.14 can be obtained.
Due to the characteristics, it is possible to appropriately roughen the surface of the chromium plating layer within a particle size range, and it becomes easy to secure the clamping property (clamping property). On the other hand, in the other particle size range, the same or more slipperiness as that of the conventional general-purpose plating bath can be obtained.

  Furthermore, the chromium plating method of the present invention can be applied not only to metal product bodies but also to product bodies such as ceramics and plastics.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to a Sargent bath and a fluorinated bath as examples.

  Basically, this is a method of performing chromium plating on a metal product main body with a granular chromium plating layer using a chromium plating bath.

  Here, as a metal product to which the present invention is applied, a certain slip prevention is required, for example, a press mold (preventing movement of a workpiece during workpiece processing), a clamp product, a feed roller, a belt pulley. It is suitable for etc.

  Moreover, since the surface of the hard chrome method of the present invention is a granular surface, it can be used as a base treatment surface of an adhesive or an oil retaining surface.

  In addition, the metal material constituting the metal product body (base material) is usually an iron alloy such as steel, but it can also be applied to non-ferrous alloys such as aluminum alloy, copper alloy (brass, bronze, etc.) and titanium alloy. is there.

  The chromium plating bath is not particularly limited, and the above-mentioned Sargent bath, silicofluorination bath, and addition bath based on them can be used.

The hard chrome plating conditions when using a Sargent bath are as follows: current density 60-1800 A / dm ² , bath voltage 4-30 V, bath temperature 25-55 ° C., preferably current density 80-200 A / dm ² , bath voltage 4- 20V, bath temperature 35-55 ° C.

The hard chromium plating conditions in the case of using a fluorofluoride bath are as follows: current density 150 A / dm ^{2 to} 1800 A / dm ² or less, bath voltage 4 to 30 V, bath temperature 25 to 55 ° C., preferably current density 180 to 300 A. / Dm ² , bath voltage 4 to 25 V, bath temperature 35 to 55 ° C.

  In each of the above cases, if the current density is too low, granular plating tends to be difficult to be generated, and conversely if too high, the adhesion of the plating layer to the substrate tends to decrease.

  Regarding the bath voltage, if it is too low, it takes time to deposit the plating. Conversely, if it is too high, the adhesion of the plating layer to the substrate tends to decrease.

  Regarding the bath temperature, if it is too low, the adhesion of the plating layer to the substrate tends to be reduced, and if it is too high, granular plating tends to be difficult to be generated.

  The plating time varies depending on the required film thickness, film characteristics (static friction coefficient, etc.) and plating conditions (current density, bath voltage, bath temperature), but from the viewpoint of productivity and film thickness, it is 4 to 4 minutes. 30 min.

  And the granular chromium plating layer formed in the surface of a metal product main body shall be a thing with an average particle diameter of 5-250 micrometers and a film thickness of 8-350 micrometers in the case of a Sargent bath. In the case of a fluorofluorination bath, the average particle size is usually more than 30 μm and less than 250 μm, and the film thickness is more than 40 μm and less than 350 μm.

  When the static friction coefficient (tan θ) of sliding friction in the chrome plating layer in each of these cases is determined under the following conditions, it is 0.17 or more, preferably from the viewpoint of clampability of a metal member such as a mold. Use 0.18 or more.

  In addition, in the case of other uses, when the purpose is an adhesive base, an oil retaining surface or the like, it may be 0.14 to less than 0.17 having an intermediate slip of less than that, When slipperiness is required, it is desirable to use one having a granular plating layer of less than 0.14.

  Here, the static friction coefficient was measured by placing a slider (slider) on each plate-like test piece, gradually tilting each plate-like test piece, and obtaining the angle θ immediately before the slider started to slide. . The tan θ at that time was defined as a relative friction coefficient.

  The slider was a 14 mmφ cylindrical body (lower 2 mmt glass + upper 10 mmtS45C; total weight 13.1 g).

  Examples, comparative examples, and control examples performed for confirming the effects of the present invention will be described below. In addition, Example 1 group and Comparative Example 1 show a Sargent bath, and Example 2 group and Comparative Example 2 show a fluorofluorination bath, respectively.

A Sargent bath having the composition shown in Table 1 was used, and a fluorination bath having a H ₂ SO ₄ concentration of 1.0 g / l in Table 1 was used.

  And the chromium plating was performed on each condition shown to Tables 2-4 with respect to a base material (SPCC).

  And about the granular chromium plating layer of each prepared plating product, while taking the micrograph, the particle size was determined and the film thickness was measured with the micrometer.

  Their micrographs (× 200 times) are shown in FIGS. 1 to 24, and the particle diameters and film thicknesses are shown in Tables 2 to 4.

  The following can be seen from the micrograph.

  By increasing the current density, a granular plating layer having a large particle size can be obtained, and by controlling the temperature and time, the particle size and film thickness of the granular plating layer can be controlled (managed).

  Furthermore, the coefficient of static friction measured based on the above for Comparative Example 1 and Examples 1-1 to 1-6 using a Sargent bath and Comparative Example 2 and Examples 2-1 to 2-8 using a fluoride bath Indicates.

  From these results, it can be seen that the coefficient of friction is low in the Sargent bath even when the film thickness is slightly small (Example 1-1 and Comparative Example 1).

  Similarly, in the fluoride bath, it can be seen that even if the film thickness is slightly small, the friction coefficient is low (Example 2-1 and Comparative Example 2).

  The case where the granular chrome plating layer is formed on the main body of the metal product has been described as an example. However, the chrome plating method of the present invention can be applied to ceramic products, plastic products, etc. other than metal products. If it is subjected to a conductive treatment, it can be expected to be applicable.

Micrograph of Comparative Example 1 Micrograph of Example 1-1 Photomicrograph of Example 1-2 Micrograph of Example 1-3 Micrograph of Example 1-4 Micrograph of Example 1-5 Photomicrograph of Example 1-6 Micrograph of Comparative Example 2 Micrograph of Example 2-1 Micrograph of Example 2-2 Micrograph of Example 2-3 Micrograph of Example 2-4 Micrograph of Example 2-5 Micrograph of Example 2-6 Micrograph of Example 2-7 Micrograph of Example 2-8 Micrograph of Example 2-9 Micrograph of Example 2-10 Micrograph of Example 2-11 Micrograph of Example 2-12 Micrograph of Example 2-13 Micrograph of Example 2-14 Micrograph of Example 2-15 Micrograph of Example 2-16 Micrograph of Example 2-17 Micrograph of Example 2-18

Claims (11)

On the metal product body, chromium plating is performed using a chromium plating bath (excluding a fluorofluoride bath) under the conditions of a current density of 60 to 1800 A / dm ² , a bath voltage of 4 to 30 V, and a bath temperature of 25 to 55 ° C. A hard chrome plating method characterized by that.   The hard chrome plating method according to claim 1, wherein the chrome plating bath is a sergeant bath. It is characterized in that chromium plating is performed on a metal product body using a fluorofluoride bath under conditions of a current density of more than 150 A / dm ^{2 and} 1800 A / dm ² or less, a bath voltage of 4 to 30 V, and a bath temperature of 25 to 55 ° C. Hard chrome plating method.   The hard chrome plating method according to claim 1, wherein the plating time is 2 to 100 minutes.   The surface of the metal product body is provided with a granular chromium plating layer by a chromium plating bath (excluding a fluorofluorination bath), and the granular chromium plating layer has an average particle diameter of 5 to 250 μm and a film thickness of 8 to 350 μm. Hard chrome plating product.   A hard chrome plating product comprising a granular chrome plating layer using a fluorofluoride bath on the surface of a metal product main body, having an average particle size of more than 30 μm and not more than 250 μm and a film thickness of more than 40 μm and not more than 350 μm.   The hard chromium plating product according to claim 5 or 6, wherein the granular chromium plating layer has a static friction coefficient of 0.17 or more.   The hard chrome plated product according to claim 5 or 6, wherein the granular chrome plated layer has a coefficient of static friction of 0.14 or more and less than 0.17.   The hard chrome plated product according to claim 5 or 6, wherein the granular chrome plated layer has a static friction coefficient of less than 0.14. Using a chromium plating bath (excluding a fluorofluoride bath) on the product body (base material), chromium is applied under the conditions of a current density of 60 to 1800 A / dm ² , a bath voltage of 4 to 30 V, and a bath temperature of 25 to 55 ° C. A hard chrome plating method characterized by performing plating. A chromium plating is performed on the product body (base material) using a fluorofluoride bath under the conditions of a current density of 150 to 1800 A / dm ² , a greedy voltage of 4 to 30 V, and a bath temperature of 25 to 55 ° C. Hard chrome plating method.

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