KR100795166B1 - Manufacturing Method of Electroless Ni-P Nano-Diamond Composite Coating - Google Patents

Abstract

The present invention relates to a composite electroless plating method having the shape, hardness (H _V ), abrasion and corrosion of the coating film according to the plating conditions of the nano diamond composite electroless Ni-P plating using the nanometer diamond. Injecting the nanodiamond powder into the water at room temperature to adjust the concentration of the nanodiamond powder solution; Dispersing the nanodiamond powder solution using ultrasonic waves after the concentration adjustment; The dispersed nanodiamond powder solution is added to a previously prepared electroless nickel plating solution, and the acidity (PH) is controlled, including the use of nano-size diamond particles, particle concentration, ultrasonic dispersion time, conditions for each PH By controlling according to the dispersion by uniformly sized nano diamond (Nano Diamond) and plating under the optimum conditions there is an effect of improving the hardness (H _V ) and wear resistance and corrosion resistance.

Nano Diamond, Composite Electroless Ni-P Plating, Corrosion Resistance, Wear Resistance, Hardness

Description

Manufacturing method of Electroless Ni-P Nano-Diamond Composite Coating}

1 to 9 are graphs showing data values calculated by measurement and analysis in Examples 1 to 9,

10a to 10e are photographs showing the surface shape of the plating film according to the diamond concentration change,

11a to 11e are photographs showing the surface shape of the plating film according to the ultrasonic dispersion time,

12a to 12e are photographs showing the surface shape of the plating film according to the PH change.

The present invention uses the diamond particles of several hundreds of nm size produced by exploding the TNT / RDX (trinitrotoluene / hexogene) compound at high temperature and high pressure state, the particle concentration, ultrasonic dispersion time, particle size according to the conditions of each PH and Zeta The present invention relates to a composite electroless plating method using nanodiamonds having the shape, hardness (H _V ), abrasion and corrosiveness of the coating film according to the optimum plating conditions in the nanodiamond composite electroless Ni-P plating by measuring the electric potential.

There is a demand for developing materials having various characteristics such as corrosion resistance, wear resistance, and lubricity. As a single material is difficult to satisfy all of these various properties, composite plating methods using a combination of materials having different properties have been actively researched and developed recently.

In general, the composite plating is vaccinated during the deposition of nickel or copper by dispersing fine particles of fine sized SiC, Al ₂ O ₃ , graphite, diamond, quartz, titanium oxide, titanium carbide and polymer particles in the electrolyte solution. It is an electrochemical material process for forming a coating layer. Among the fine particles used for composite plating, diamond particles have high hardness, low coefficient of friction, and are chemically stable in an atmosphere of air, acid, or salt, and have been used for a long time in grinding and cutting tools. With the development of modern science and technology, micrometer (μm) sized composite plating is not suitable for the characteristics required by the industrial sector. However, composite plating using nanoparticles of reinforcing phase has been widely applied to research and industry because of its excellent properties.

Nanodiamonds can be used in liquid or powder form depending on the purpose of the product.Purity can be divided into nanodiamond mixtures, high purity nanodiamond mixtures, and ultra high purity nanodiamonds.They are used in the surface treatment of electroplating additives, gold, platinum, silver, etc. It is used in various fields such as precious metal plating, anodization of aluminum and aluminum alloys, nano advanced abrasive materials, and used in industrial tools, molds, and electroplating stabilization fields. And the advantages of surface treatment and coating of nano-levels, and the conventional plating method using nanodiamonds has a disadvantage of inferior wear resistance and corrosion resistance due to the use of nanodiamonds having irregular particle sizes.

The present invention has been proposed to solve the above problems of the prior art, using nano-sized diamond particles, nano diamond of uniform size by controlling the concentration of the particles, ultrasonic dispersion time, conditions for each PH It is an object of the present invention to provide a nanodiamond composite electroless plating method according to the optimum plating conditions.

In the present invention for achieving the object, the step of adjusting the concentration of the nanodiamond powder solution by adding nanodiamond powder to water at room temperature; Dispersing the nanodiamond powder solution using ultrasonic waves after the concentration adjustment; It is characterized in that it comprises a; step of adding the dispersed nanodiamond powder solution to the prepared electroless nickel plating solution and adjust the acidity (PH).

Here, the concentration of the nanodiamond powder in the concentration control process is adjusted to 1g / ℓ ± 0.5, the dispersion process is dispersed in the nanodiamond powder to a uniform size and ultrasonic dispersion time in the range of 30 ± 5 minutes (min) The average particle size of the controlled and dispersed nanodiamond powder is 175 nanometers (nm), the acidity (PH) control is adjusted by using 10% sodium hydroxide (NaOH) and sulfuric acid (H ₂ SO ₄ ) and acidity (PH The adjustment range is characterized by 5 ± 0.5.

In addition, the particle size of nanodiamonds having the highest zeta-potential value among the nanodiamond concentration, ultrasonic dispersion time, and acidity control condition is 159 nanometers (nm) in size and is dispersed in the smallest particle size. It is done.

In addition, the nanodiamond powder used is characterized in that the nanometer (nm) size.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 9 are graphs showing data values calculated by measurement and analysis in Examples 1 to 9, and FIGS. 10A to 10E are photographs showing the surface shape of the plating film according to the diamond concentration change. 11A to 11E are photographs showing the surface shape of the plating film according to the ultrasonic dispersion time, and FIGS. 12A to 12E are photographs showing the surface shape of the plating film according to the PH change.

First, the concentration control process is a process for adjusting the concentration of nanodiamond powder by adding nanodiamond powder to water at room temperature. The nanodiamond powder plating solution is prepared by adding 250 milliliters (ml) of water at room temperature and 1 g of nanodiamond powder. The concentration of 1g / L ± 0.5 will be adjusted, the nanodiamond powder used here can be improved wear resistance and corrosion resistance by using a nanometer (nm) size.

 The ultrasonic dispersion process is a process for dispersing the nanodiamond powder solution of which concentration is controlled by using ultrasonic waves to disperse the nanodiamond powder solution in a uniform size, and the ultrasonic dispersion time for dispersing in a uniform size is 30 ± 5 minutes ( min) is controlled and dispersed in the average particle size of the dispersed nanodiamond powder is a uniform size of 175 nanometers (nm).

The acidity control process is a process of injecting the nanodiamond powder dispersed in a uniform size of 175 nanometers into a previously prepared electroless nickel plating solution and adjusting the acidity (PH). The pH control range is 5 ± 0.5. The acidity is controlled by controlling the change to acidity or alkali using 10% sodium hydroxide (NaOH) and sulfuric acid (H ₂ SO ₄ ).

Through the concentration control process, the dispersion process and the acidity control process, the nanodiamond powder plating solution dispersed in a uniform size is coated on the workpiece to a desired thickness, and the plating is performed by the nanodiamond powder solution having a uniform particle size. Workpieces will have improved wear and corrosion resistance.

In addition, the particle size of nanodiamonds having the largest zeta-potential value among the nanodiamond concentration, ultrasonic dispersion time, and acidity control condition is dispersed to the smallest particle size of 159 nanometers (nm). Zeta potential is the surface electrical property of colloidal particles suspended in a liquid.It is used as a reference for the electrical attraction and repulsion of suspended materials or surfaces such as suspended materials and filters.In general, the magnitude of Zeta potential is mV. to be.

Hereinafter, the detailed description of the present invention was based on the following examples.

First, the particle size of the diamond used in the experiment and the concentration of particles in the diamond powder suspension (0.5 ~ 3.0g / ℓ), ultrasonic dispersion time (0 ~ 60min), Diamond particle size and Zeta potential with PH (3 ~ 7) change were measured by Pals Zeta Potential Analyzer Ver. The surface shape was measured by the S4700 FE-SEM of HITACHI, and the plating thickness was measured by XULM-XYM XRF (X-Ray Fluorescence) of FICHER. The hardness (H _V ) of the plated layer was used as a micro-Vickers hardness tester of the HM-112 Model of MITUTOYO Co., Ltd., and the average value of each specimen was measured 10 times for 10 seconds under a load of 100 g.

Tribometer ball-on-disk type was used for wear characteristics.

Corrosion was also performed for 5 hours at 5% NaCl _{2 and} room temperature (25 ℃) according to KS D 9502 and KS D 8334. Corrosion area is shown by calculating the corroded area to the total area of the specimen.

Example 1

The first embodiment shows the particle size and Zeta Potential value according to the diamond concentration when the ultrasonic dispersion time is set to 30 minutes in the suspension, Figure 10a ~ 10e is a photograph showing the surface shape according to the concentration change and dispersion The solution was mixed with an electroless Ni-P plating solution and plated at 90 ± 2 ° C. for 60 min.

0.5g / ℓ 1.0 g / ℓ 1.5g / ℓ 2.0 g / ℓ 3.0 g / ℓ Particle Size (nm) 225.9 175 387.5 853.8 3547.1 Zeta Potential (mV) 25.60 18.07 6.09 5.73 3.23

As can be seen in Table 1 and FIG. 1, the zeta potential value also decreased as the diamond concentration increased, and the particle size increased as the concentration increased.

Example 2

The second embodiment shows the particle size and zeta potential value according to the ultrasonic dispersion time when the diamond concentration in suspension is 1 g / l and acidity (PH) is 4.36, and FIGS. 11a to 11e illustrate ultrasonic dispersion time. It is a photograph showing the surface shape of the plating film according to 0 minutes, 15 minutes, 30 minutes, 45 minutes, and 60 minutes.

0 min 15 minutes 30 minutes 45 minutes 60 minutes Particle Size (nm) 256 213 159 163 181 Zeta Potential (mV) 12.39 19.98 22.74 22.38 19.46

As can be seen in Table 2 and Figure 2, the particle size tends to decrease gradually with ultrasonic dispersion time, and after a certain time, that is, 30 minutes, the size starts to increase and the zeta potential is different. Increases with increasing dispersion time and decreases after 30 minutes.

Example 3

The third embodiment shows the particle size and zeta potential value according to the change in acidity (PH) when the diamond concentration in suspension is 1 g / L and the ultrasonic dispersion time is 30 minutes, and FIGS. 12A to 12E are PH. The surface shape of the plating film according to the change is shown.

12A and 12B show that when the pH of the plating solution is a strong acid (PH3, 4), diamond particles are hardly vaccinated on the surface, and the electroless Ni-P plating is hardly performed because it is lower than the appropriate pH of the electroless Ni-P plating. . This is considered to be a phenomenon caused by precipitation immediately without dispersing in the extreme pH because the solubility of the fine particles depend on the pH. On the other hand, as shown in Figure 12d and 12e shows a high Zeta potential value at PH 5, diamond particles were also vaccinated with particles having a small size deviation on the surface of the coating surface, the diamond particles were agglomerated and vacancy again as the PH was increased.

PH 3 PH 4 PH 5 PH 6 PH 7 Particle Size (nm) 358.9 174.2 194.9 192.9 291.7 Zeta Potential (mV) 6.64 7.36 21.91 9.87 8.50

As can be seen in Table 3 and Figure 3, the particle size (nm) in the acidity (PH) 4, 5, 6 has little change, began to increase from the acidity (PH) 7,

Zeta potential increased with acidity (PH), peaked at acidity (PH) 5, and decreased again from acidity (PH) 6.

That is, as shown in Examples 1 to 3, as the particle concentration increased from 0.5 to 3.0 g / L, the Zeta potential decreased, and thus the diamond particle size increased. Zeta dislocations tended to increase with increasing ultrasonic dispersion time, but began to decrease after a certain time (30 min), and the particle size showed a minimum size at 30 min, after which the particle size increased again. The Zeta potential value was the highest at pH 5, and the particle size was almost constant at PH 4-6, and gradually increased with increasing pH.

<  Evaluation of Composite Electroless Nickel Plating Using Nanodiamond Powder Solution>

The experimental conditions were fixed factors, the base was a steel plate (3x3cm), the plating temperature was 90 ° C (± 2 ° C), the plating time was 60 minutes, and the heat treatment condition was 350 hours in argon gas at 2 hours The factor is diamond concentration (g / L): 0.5, 1.0, 1.5, 2.0, 3.0, ultrasonic dispersion time (400kw) is 0, 15, 30, 45, 60, and the pH of the plating liquid is 3, 4, 5, 6 , Seven.

Here, the plating rate (μm / 60min) of each specimen is a value measured by the plating thickness per plating time, and the vacancy rate (%) of the diamond particles is a value obtained by converting the diamond particle area to the total area of the FE-SEM image. Uniformity was calculated through Equation 1, x is the average area value of the diamond particles, S is the sum of the square of the difference between the individual x _i and the average value x, n is the number of diamond particles measured.

Particle Size Uniformity  = x / √S / (n-1) (S = ∑ (x _i -x) ² )

Nanodiamond  Mechanical and Chemical Properties According to Concentration Changes

Example 4

 The fourth embodiment shows the plating rate (μm / 60 min), diamond vacancy rate (%) and particle size uniformity of the composite plating according to the diamond concentration change when the ultrasonic dispersion time is 30 minutes.

0.5g / ℓ 1.0 g / ℓ 1.5g / ℓ 2.0 g / ℓ 3.0 g / ℓ Plating speed (㎛ / 60min) 17.87 17.51 19.23 16.41 17.93 Diamond vacancy rate (%) 20.8 25.3 28.5 33.7 42.9 Particle Size Uniformity 1.5 × 10 ³ 0.95 × 10 ³ 1.3 × 10 ³ 2.3 × 10 ³ 3.0 × 10 ³

As can be seen in Table 4 and Figure 4, the plating rate is almost constant irrespective of the diamond concentration change, the vacancy rate (%) is increased proportionally as the concentration is increased, the particle size uniformity is small value The more uniform particles were, the lower the value was at 1 g / l and the uniformity increased with increasing concentration.

Example 5

The fifth embodiment shows the hardness, wear and corrosion characteristics of the composite plating according to the diamond concentration change.

0.5g / ℓ 1.0 g / ℓ 1.5g / ℓ 2.0 g / ℓ 3.0 g / ℓ Hardness (Hv) 836 890.5 898.5 848.6 917.6 Coefficient of friction 0.807 0.591 0.711 0.798 0.747 Corrosion area (%) 29.67 24.67 30.67 35.67 46.67

As can be seen in Table 5 and Figure 5, the hardness is almost constant irrespective of the diamond concentration change, the coefficient of friction and the corrosion area (%) showed the best value at 1g / ℓ, as the concentration increases The low coefficient of friction and corrosion area (%) at 1 g / l is due to the presence of small, uniformly sized particles, due to the Zeta potential and the degree of dispersion.

-Mechanical and chemical properties according to ultrasonic dispersion time

Example 6

The sixth embodiment shows the plating rate (μm / 60min), diamond vacancy rate (%) and particle size uniformity of the composite plating according to the ultrasonic dispersion time under the conditions of diamond concentration 1g / ℓ and PH 4.3.

0min 15min 30min 45min 60min Plating speed (㎛ / 60min) 17.68 17.60 17.51 17.85 17.78 Diamond vacancy rate (%) 28.4 25.1 25.3 24.9 25.8 Particle Size Uniformity 1.35 × 10 ³ 1.2 × 10 ³ 0.9 × 10 ³ 1.6 × 10 ³ 1.9 × 10 ³

As can be seen in Table 6 and Figure 6, the plating rate (㎛ / 60min), the diamond vacancy rate (%) is almost constant value, the uniformity of the particle size shows the lowest value in 30 minutes and as time passes The uniformity value is shown to increase.

Example 7

The seventh embodiment shows the hardness wear and corrosion characteristics of the composite plating according to the ultrasonic dispersion time.

0min 15min 30min 45min 60min Hardness (Hv) 933 888 890.5 883.5 895 Coefficient of friction 0.873 0.642 0.591 0.777 0.853 Corrosion area (%) 51.5 36.0 31.5 35.33 39.0

As can be seen in Table 7 and Figure 7, the hardness (H _V ) is almost constant, the coefficient of friction and the corrosion area (%) shows the optimum value at 30 minutes particle size, zeta potential and particle size uniformity, Above that, it tends to increase gradually.

-Mechanical and Chemical Properties According to PH Change

Example 8

The eighth embodiment is a table showing the plating rate (占 퐉 / 60min), diamond vacancy rate (%) and particle size uniformity of the composite plating.

PH 3 PH 4 PH 5 PH 6 PH 7 Plating speed (㎛ / 60min) 1.88 8.80 15.69 18.0 18.47 Diamond vacancy rate (%) 0.139 0.320 30.50 36.681 20.491 Particle Size Uniformity - - 1.0 × 10 ³ 2. × 10 ³ 0.65 × 10 ³

As can be seen in Table 8 and Figure 8, the plating rate (㎛ / 60min) tends to increase with PH, the vacancy rate (%) and particle size uniformity increases and begins to decrease at PH 7.

Example 9

The ninth embodiment shows the hardness wear and corrosion characteristics of the composite plating according to the PH change.

PH 4  PH 5  PH 6  PH 7 Hardness (Hv) 548 877 858.5 935.8 Coefficient of friction 0.954 0.607 0.636 0.712 Corrosion area (%) 59.5 31.5 31.3 41.67

As can be seen in Table 9 and Figure 9, the hardness is almost constant, the coefficient of friction and the corrosion area (%) is excellent at PH 5, 6, and then began to increase.

The plated film is greatly affected by the change in pH of the plating solution, and the most excellent film property is 4.5 to 5.5, which is almost identical to the appropriate pH of the electroless Ni-P plating.

<Comparative Table 1>

Electroless Ni-P Plating and Nanodiamond Composite Electroless Ni-P Plating

Electroless Ni-P Plating Nano Diamond Composite Electroless Ni-P Plating Plating speed (㎛ / 60min) 17.40 17.51 Hardness (Hv) 828 890 Coefficient of friction 0.910 0.591 Corrosion area (%) 58.67 24.07

As shown in Table 10, the friction coefficient and the corrosion area (%) show a large difference compared to the physical property values of the composite electroless nickel plating using the nanodiamond powder solution.

Through the first to tenth embodiments of the present invention, it can be seen that as the diamond concentration increases, the value of Zeta Potential (mV) decreases, so that aggregation of particles may occur as the concentration increases. In contrast to decreasing zeta potential, the vacancy rate (%), friction coefficient, and corrosion area (%) tend to increase, and the particle size uniformity is evenly distributed in average particle size at 1 g / l. You can see,

In addition, the ultrasonic dispersion decreases the zeta potential value that increases after a certain time (30 min), and not only the particle size but also the friction coefficient, corrosion area (%) decreases over time, and then increases after 30 minutes. As a result of checking the plating properties according to the PH change, the results of the zeta potential value and the tendency of other property values were almost identical, and it was confirmed that a film having excellent plating properties was obtained at PH 5. .

In addition, as shown in Comparative Example 1, as a result of comparing the property value of the diamond composite plating with the electroless Ni-P plating, it showed a large difference in hardness, friction coefficient, and corrosion area (%), and the nanodiamond composite electroless Ni- It is confirmed that P plating is better, and in the nanodiamond composite electroless Ni-P plating, an excellent plating film can be obtained at a diamond concentration of 1 g / l, ultrasonic dispersion time 30 minutes, and PH 5.

However, the present invention is not limited to the preferred embodiments of the above-described features, and various modifications can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Of course, such changes will fall within the scope of the claims.

In the present invention, using nano-sized diamond particles, the hardness (H _V ) by controlling the concentration of the particles, the ultrasonic dispersion time, pH-specific conditions to be dispersed in a uniform size of nano diamond (Nano Diamond) by plating at the optimum conditions It is effective in improving wear and corrosion.

Claims (6)

delete delete delete delete Adding 1 g of nanodiamond powder to 250 ml of room temperature water to adjust the concentration of the nanodiamond powder solution to 1 g / L ± 0.5; Dispersing the nanodiamond powder solution after the concentration adjustment using an 400 kw ultrasonic wave so that the average particle size of the nanodiamond powder is about 175 nm for 30 ± 5 minutes of ultrasonic dispersion time; The dispersed nanodiamond powder solution was added to an electroless nickel plating solution at 90 ± 2 ° C., and the acidity (PH) was adjusted to 5 ± 0.5 using 10% sodium hydroxide (NaOH) and sulfuric acid (H ₂ SO ₄ ) for 60 minutes. In the composite electroless plating method using a nanodiamond powder solution comprising a step of adjusting, The particle size of the nanodiamond when the nanodiamond concentration control of the 1g / ℓ ± 0.5, 30 ± 5 minutes ultrasonic dispersion time and the acidity (PH) of 5 ± 0.5 has the largest zeta potential value among the conditions Composite electroless plating method using nanodiamond powder solution, characterized in that dispersed in 159 nanometers (nm) size. delete

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