RU2375494C2 - Method of production of metal-diamond chemical coating - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention refers to machine building and can be used for production of chemical coating on parts out of materials operating under excessive wear, high pressure and at presence of aggressive mediums. With successive solving of components a solution is prepared; further surfaces are chemically or electric-chemically treated; then there is performed chemical application of coating from solution. This is followed with cold and hot water washing and drying. Nano diamonds with dimension of diamond aggregates in the range of 0.004-0.1 mcm at amount of 2-20 g/l are introduced into solution for chemical application of coating. In specific cases of the invention nano diamonds are introduced into solution in form of hydrosol or powder, or suspension.

EFFECT: upgraded physic-chemical properties of coating.

2 cl, 8 tbl, 4 ex

Description

The invention relates to mechanical engineering and can be used to obtain chemical coatings on parts from various materials (metals, ceramics, polymers) that work under conditions of increased wear, high pressures, temperatures, in the presence of aggressive environments.

A distinctive feature of chemical coatings is the high uniformity of their deposition on the surface of the products. Due to the low porosity, such coatings possess a combination of unique qualities: increased microhardness, wear resistance and resistance in aggressive environments, which is of great importance during their operation in industry. The advantage of obtaining a coating by the chemical method compared to the electrochemical method is the possibility of deposition of metals on surfaces of different profiles from various materials, including plastics, inorganic, ceramic materials, etc. Chemical coatings can be applied to any surface area, as well as on internal surfaces to which the supply of electric current is difficult. Coatings are uniform over all surface areas of any complex products.

To improve the microstructure and performance properties of coatings, various inert particles are introduced into the metallization electrolytes: corundum, silicon carbide, titanium dioxide, molybdenum disulfide (Sayfulin RS Composite coatings and materials. - M., 1977, p. 238- 241) and synthetic diamonds (Synthetic superhard materials. Kiev. Naukova Dumka, 1986, Volume 2, pp. 7-32). Previously published results show that the addition of nanodiamonds to metal deposition processes improves the hardness of electrochemical coatings (Burkat GK, Fujimura T., Dilator VY, Rollover EA Veretennikova M.V., "Preparation of composite electrochemical nickel - diamond and iron-diamond coatings in the presence of detonation synthesis nanodiamonds, "Diamond and Related Materials (14) 1761-1764, 2005). At the same time, it has been empirically established that nanoscale diamonds added to the electrolyzer can improve the tribotechnical properties of electrochemical coatings (A. Gurga, V. Mohalin D. Rere, C. Picardi, Y. Gogotsi "Nanoindidentation Study of the Effect of Nanodiamond Additives on Electroless Deposition Nickel - Boride Coatings ").

A known method for producing a composite coating with enhanced anti-corrosion properties due to the use of ultrafine diamonds (nanodiamonds) of 0.001-0.120 microns in size in the electrolyte as solid particles, RF patent No. 2169798 (publ. BI No. 18, 2001, p. 289). However, with the electrochemical method by which the coating described above is applied, difficulties arise when applying high-quality coatings to internal and complex surfaces, to which the supply of electric current is difficult.

The prior art method for chemical nickel plating of steel parts (prototype) RF patent No. 2091502 (publ. BI No. 27, 1997, p. 323), including the preparation of a solution for coating by sequential dissolution of the components, surface preparation by chemical and (or) electrochemical treatment, coating from a solution, washing with hot and cold water and drying coatings.

The disadvantage of the above method is that the method does not provide the required high physical and mechanical characteristics and corrosion resistance of the coatings.

The objective of the invention is the creation of a method that improves the quality of chemical coatings.

The problem is solved by the proposed method for producing metal-diamond coatings by chemical deposition, which includes preparing the solution by sequential dissolution of the components, preparing the surface by chemical and (or) electrochemical treatment, chemical coating of the solution, washing with cold and hot water, drying, while in the solution for chemical coating, nanodiamonds are introduced with a diamond aggregate size of 0.004 ... 0.100 microns in an amount of 2-20 g / l.

In special cases, the nanodiamond is introduced into the solution in the form of a hydrosol, or powder, or suspension.

The proposed solution differs from the prototype by introducing nanodiamonds with an aggregate size of 0.004 ... 0.100 microns in an amount of 2-20 g / l into a solution for chemical coatings.

Nanodiamonds can be introduced into the solution in the form of a hydrosol, or powder, or suspension.

The solution of this problem, namely the increase in microhardness, wear resistance and corrosion resistance, occurs due to the improvement of the microstructure of the metal-diamond coating. When a nanodiamond is introduced into the composition of a solution for the deposition of a metal-diamond coating, the formation of an ordered submicrocrystalline structure is observed. The smaller the size of the diamond aggregates, the more perfect the structure and the higher the anisatropy of the properties of the precipitate, which determine the increase in the operational characteristics of the coating - microhardness, wear resistance and corrosion resistance.

The content of the nanodiamond in the solution (electrolyte) is 2-20 g / l, an increase in the nanodiamond above the specified boundary will lead to a thickening of the solution, which will immediately affect the uniformity of the applied coating, with a decrease in the nanodiamond content below the specified limit, its effect is hardly noticeable (Tables 2, 3 , 6).

The choice of sizes of nanodiamonds is due to the fact that going beyond these limits will lead to the fact that with an increase in the size of aggregates, the specific surface area of nanoparticles and the effect of ultrafine diamonds on the properties of coatings decrease. Nanodiamonds with a size of less than 0.004 microns are almost impossible to obtain and this is associated with significant economic costs.

The influence of the dimension of nanodiamond aggregates on the properties of coatings is presented in Tables 7, 8.

The simplest method for preparing a solution for chemical coating involves the use of a diamond hydrosol with a concentration of a dispersed phase of 50 g / dm ³ and a diamond aggregate size of 0.004-0.100 microns. When using nanodiamonds in the form of a suspension or powder, where the size of diamond aggregates can be up to 2.5 μm or more, the prepared solution must be worked out using any of the disaggregation methods, which will reduce the aggregates to the desired size (for example, ultrasonic treatment, processing on a disintegrator, processing on a dismembrator or rotary pulsation apparatus, etc.).

The inventive method is illustrated by the following examples, the temperature of the solution and its composition is maintained within the limits accepted for a particular chemical process.

Example 1

To apply a chemical nickel coating with nanodiamonds to steel and cast iron surfaces of the matrix, a solution of the following composition was used, g / l:

Nickel sulfate 22 Sodium Hypophosphite 23 Ammonium chloride thirty Ammonia 45 Sodium Acetate 45 Nanodiamonds 2-20

The process is carried out at a pH of 8.0-9.0 and a temperature of 84-89 ° C. The preparation of a solution for nickel plating is carried out as follows: all bulk components of the composition are dissolved in a small amount of demineralized water. Then, solutions of ammonium chloride and sodium acetate are successively introduced into the solution of nickel sulfate with mechanical stirring. The resulting composition is defended and filtered. Then, nanodiamonds, a solution of sodium hypophosphite are introduced into this composition and adjusted to the calculated volume by adding demineralized water. After that, check the pH of the solution and inject ammonia in an amount sufficient to achieve pH values from the range of 8.0-9.0.

The surface treatment of metals is carried out by standard methods: steel and cast iron matrices are treated in a universal alkaline solution for 2-5 minutes at a temperature of 60-70 ° C, the composition of which is shown in table 1.

Table 1 Composition component Concentration, g / dm ³ NaOH 10-15 Na ₂ CO ₃ 20-25 Na ₃ PO ₄ 20-25 Na ₂ SiO ₃ 15-20

The finished nickel-plating solution is heated to the operating temperature with constant stirring. The metal matrix is immersed in the prepared solution and maintained there for a predetermined time. The finished coating is washed first with cold, then with hot demineralized water at a temperature of 70-90 ° C. The coating is dried in air. Comparative characteristics of nickel coatings obtained from solutions with and without nanodiamonds on steel are given in Table 2, in Table 3 on cast iron.

table 2 Object / subject The claimed technical solution one 2 3 four 5 Solution composition Nickel sulfate 22 22 22 22 22 Sodium Hypophosphite 23 23 23 23 23 Ammonium chloride thirty thirty thirty thirty thirty Sodium Acetate 45 45 45 45 45 Ammonia fifty fifty fifty fifty fifty Nanodiamonds one 2 10 twenty 22 Dispersed phase The size of nanodiamonds, microns 0,074 Heating mode Temperature ° C 85 The acidity of the composition pH 8.5 Characteristics of coatings without nanodiamonds Microhardness, kgf / mm ² 432 Characteristics of coatings with nanodiamonds Microhardness, kgf / mm ² 460 792 782 789 779 Increase wear resistance 1,1 1.8 2.6 3.2 2.5 Increased corrosion resistance 1,0 3.8 3.4 2,3 3,1

Table 3 An object The claimed technical solution Option one 2 3 four 5 Solution composition Nickel sulfate 22 22 22 22 22 Sodium Hypophosphite 23 23 23 23 23 Ammonium chloride thirty thirty thirty thirty thirty Sodium Citrate 45 45 45 45 45 Ammonia fifty fifty fifty fifty fifty Nanodiamonds one 2 10 twenty 22 Dispersed phase The size of nanodiamonds, microns 0,074 Heating mode Temperature ° C 85 The acidity of the composition pH 8.7 Characteristics of coatings without nanodiamonds Microhardness, kgf / mm ² 510 Characteristics Microhardness, kgf / mm ² 665 816 828 839 812 coatings with Increase wear resistance 1,1 2.7 2.9 2.9 2.1 nanodiamonds Increased corrosion resistance 0.9 1.3 2.2 2.5 2,4

Example 2

For applying a chemical nickel coating with nanodiamonds on the surface of aluminum, ceramic and polymer matrices, we used the composition shown in example 1, the sequence of operations and coating conditions, excluding the operation of preparing the surface for coating, are also shown in example 1.

The surface preparation of aluminum, ceramic and polymer matrices is carried out in a 5% sodium hydroxide solution at a temperature of 60-70 ° C for 15-20 seconds. Surface preparation is completed by washing the matrices with demineralized water.

Example 3

To apply a chemical copper coating with nanodiamonds to steel and cast iron matrices, the following composition was used as a copper plating solution, g / l:

CuSO ₄ · 5H ₂ O one hundred NaOH one hundred glycerol one hundred formalin (33%) twenty Temperature ° C 15-25 Nanodiamonds 2-20

Before applying copper coatings, the surfaces of the matrices of steel and cast iron are subjected to the following preparatory operations: degreasing, etching, activation.

Table 4 shows the composition of the electrolyte for the electrochemical treatment of steel and cast iron.

Table 4 Name of material Concentration, g / dm ³ NaOH 10 ÷ 20 Na ₂ CO ₃ 20 ÷ 40

Na ₃ PO ₄ 20 ÷ 40 Liquid glass 3 ÷ 5

Temperature ° C 50-80 The current density, A / DM ² 2-10 Duration min 2-10 (at the cathode)   1-5 (at the anode)

Etching of parts is carried out in acidic electrolyte (table 5)

Table 5 Name of material Concentration, g / dm ³ Hcl 150 ÷ 350 Urotropin 40 ÷ 50

Temperature ° C 20-30 Duration min 0.1-0.3

Activation of cast iron steel parts is carried out by treatment in hydrochloric acid with a density of 1.19 g / cm ³ (concentration of 50-100 g / dm ³ ).

After each of the preparatory operations, the parts are thoroughly washed in cold tap water and then in distilled water.

Comparative characteristics of copper coatings obtained from solutions with and without nanodiamonds on steel are given in Table 6.

Table 6 An object The claimed technical solution Option one 2 3 four 5 Solution composition Blue vitriol one hundred one hundred one hundred one hundred one hundred Sodium hydroxide one hundred one hundred one hundred one hundred one hundred Glycerol one hundred one hundred one hundred one hundred one hundred Formalin (33%) twenty twenty twenty twenty twenty Nanodiamonds one 2 10 twenty 22 Dispersed phase The size of nanodiamonds, microns 0,074 Heating mode Temperature ° C 22 The acidity of the composition pH 11.5 Characteristics of electrolyte coatings without nanodiamonds Microhardness, kgf / mm ² 132 Characteristics Microhardness, kgf / mm ² 138 147 157 168 164 coatings with Increase wear resistance 1,2 1.7 2,4 2.6 2.2 nanodiamonds Increased corrosion resistance 0.8 1,1 1.9 3.0 2.2

Example 4

For applying a copper chemical coating with nanodiamonds on the surface of aluminum, ceramic and polymer matrices, the composition shown in Example 3 was used.

The surface preparation of aluminum, ceramic and polymer matrices is carried out in a 5% sodium hydroxide solution at a temperature of 60-70 ° C for 15-20 seconds. Surface preparation ends with washing the matrices with demineralized water. Further, the process of obtaining coatings is carried out as in example 3.

Thus, the use of nanodiamonds as an electrolyte filler can significantly improve the quality indicators of chemical coatings, thereby significantly increasing the life of the products on the surface of which these metal-diamond coatings are applied. The application of this method in machine, instrument making and other fields is effective, providing an increase in the physicomechanical characteristics of chemical coatings.

Table 7 Object / subject The claimed technical solution one 2 3 four 5 Solution composition Nickel sulfate 22 22 22 22 22 Sodium Hypophosphite 23 23 23 23 23 Ammonium chloride thirty thirty thirty thirty thirty Sodium Acetate 45 45 45 45 45 Ammonia fifty fifty fifty fifty fifty Nanodiamonds 5 5 5 5 5 Dispersed phase The size of nanodiamonds, microns 0.004 0.018 0,052 0,074 0,120 Heating mode Temperature ° C 84 The acidity of the composition pH 8.3 Characteristics of coatings without nanodiamonds Microhardness, kgf / mm ² 510 Characteristics Microhardness, kgf / mm ² 802 794 788 784 761 coatings with Increase wear resistance 3.2 2.6 2.5 1.8 1,1 nanodiamonds Increased corrosion resistance 3.8 3.4 3,1 2,3 1,0

Table 8 An object The claimed technical solution Option one 2 3 four 5 Solution composition Copper sulfate, g / l one hundred one hundred one hundred one hundred one hundred Caustic soda, g / l one hundred one hundred one hundred one hundred one hundred Glycerin, g / l one hundred one hundred one hundred one hundred one hundred Formalin (33%), g / l twenty twenty twenty twenty twenty Nanodiamonds, g / l 5 5 5 5 5 Dispersed phase The size of nanodiamonds, microns 0.004 0.012 0,052 0,074 0,120 Heating mode Temperature ° C 22 The acidity of the composition pH 11.5 Characteristics of coatings without nanodiamonds Microhardness, kgf / mm ² 132 Characteristics Microhardness, kgf / mm ² 188 179 175 171 161 coatings with Increase wear resistance 2.9 2.7 2.2 2.1 1.4 nanodiamonds Increased corrosion resistance 2.5 2,3 1.9 1.8 1,5

Claims (2)

1. A method of producing metal-diamond coatings by chemical deposition, including preparing a solution by successive dissolution of the components, preparing surfaces by chemical or electrochemical treatment, chemical coating from a solution, washing with cold and hot water, drying, characterized in that nanodiamonds are introduced into the solution for chemical coating with the size of diamond aggregates in the range of 0.004-0.1 microns in an amount of 2-20 g / l. 2. The method according to claim 1, characterized in that the nanodiamond is introduced into the solution in the form of a hydrosol or powder, or suspension.