CN1699622A - Preparation method of self-lubricating chemical composite coating - Google Patents

Abstract

The present invention relates to a preparation method by self-lubrication composite electroless plating. It belongs to the field of electroless plating. The procedure is: 1) Fluorine carbon surfactant C20H20F23N2O4I which is commonly used for foam extinguisher is dissolved in PTFE latex emulsion to form mixture A, and SiC or Si3N4 or Al2O3 is dissolved in cetyl trimethyl ammonium bromide to form mixture B. 2) Preparation of plating solution, i.e. nickel sulfate, lactic acid, sodium acetate, sodium hypophosphite, propenysulfocarbamide are added in plating cell at room temperature, and pH is adjusted with sodium hydroxide. 3) Composite electroless plating: the mixture said A and said B are added in the plating solution prepared in step 2) and then heated. Consistent stirring is kept during plating and then self-lubrication composite electroless plating layer is obtained. The invention adopts different suitable surfactants depending on different grains to improve Zeta potential of the grain surfaces and suspensibility of the grains in plating solution through adsorption effect of different grains on different surfactants so as to further realize co-deposition of grains.

Description

Preparation method of self-lubricating chemical composite coating

technical field

The invention relates to a preparation method of an chemical composite coating, in particular to a preparation method of a self-lubricating chemical composite coating, and belongs to the technical field of chemical plating.

Background technique

For a long time, electroless plating and chemical composite plating technologies have been more and more widely used due to their simple operation and low cost. The Ni-PX (X is SiC, Al ₂ O ₃ , Si ₃ N ₄ and other hard particles) composite coating obtained by the above process has good wear resistance; while Ni-PX (X is polytetrafluoroethylene, graphite , MoS ₂ and other lubricating particles) composite coating has good anti-friction performance. These two types of composite coatings are used in many industries involving friction and wear conditions. However, with the rapid development of technology, people have higher and higher requirements for materials. Although the first material mentioned above has good wear resistance, it often has a high friction coefficient, causing serious noise pollution and mechanical vibration loss; the second This material has a very low friction coefficient due to the presence of lubricating particles, especially the composite coating containing polytetrafluoroethylene (PTFE) particles, but this material has poor wear resistance under high-load low-speed and high-load high-speed wear conditions property, so that the material wears seriously and cannot meet certain conditions of use. Based on the above reasons, there is an urgent need for a new type of composite coating that is both wear-resistant and friction-reducing. At present, the self-lubricating chemical composite coatings that have been researched and developed at home and abroad include Ni-P-PTFE-SiC, but due to the large difference in the physical properties of PTFE and SiC particles such as density and adsorption, the two kinds of particles are different in the co-deposition process. The interfacial effect is easy to occur between them, so that the particle deposition is rare and the distribution is extremely uneven, so that the wear resistance and friction reduction performance of the composite coating cannot meet the requirements.

Found through the retrieval of prior art document, Y.S.Huang, X.T.Zeng, I.Annergren et al. in " the development of chemical plating Ni-P-PTFE-SiC composite coating " one article (" surface coating technology " 2003, 167 : 207-211) reported that only fluorocarbon surfactants were used to promote the deposition of PTFE and SiC particles. In this method, PTFE emulsions were treated with fluorocarbon surfactants, so that the surface potential of PTFE particles was significantly improved, while the ceramic particles were resistant to fluorine. The adsorption of carbon surfactant is poor, and as a result, the surface potential of ceramic particles remains at a low level, and the obvious potential difference between the two kinds of particles makes the particles appear inhomogeneous during deposition.

Contents of the invention

The purpose of the present invention is to propose a kind of preparation method of self-lubricating chemical composite coating in view of the deficiencies in the prior art, so that it adopts suitable surfactants for different particles, and absorbs different surfactants by different particles. Improve the Zeta potential of the particle surface and the suspension in the plating solution, and further realize the co-deposition of particles.

The present invention is achieved through the following technical solutions. The method of the present invention includes particle pretreatment, preparation of plating solution, and chemical composite plating. The specific steps are as follows:

1) First, dissolve the fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I used in the foam fire extinguishing agent and the PTFE emulsion to obtain the mixed solution A, and then add cetyltrimethylammonium bromide and SiC Or Si ₃ N ₄ or Al ₂ 0 ₃ ceramic particles were dissolved to obtain the mixed solution B;

2) Plating solution preparation: the electroless nickel alloy plating solution is an acidic electroless nickel plating solution, that is, add nickel sulfate 18-30g/L, lactic acid 15-35ml/L, and sodium acetate 10-20g to the plating tank in sequence at room temperature /L, sodium hypophosphite 15~40g/L, propenyl thiourea 0.1~0.3mg/L, adjust the pH value with sodium hydroxide;

3) Chemical composite plating: the chemical composite plating process is adopted, that is, the mixed solutions A and B are added to the acidic plating solution prepared in step 2, the plating solution is heated, and the plating process requires constant stirring to obtain a self-lubricating chemical composite plating layer.

The mass ratio of the fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I to the PTFE emulsion is 1:30˜1:55.

The concentration of the cetyltrimethylammonium bromide is 0.07-0.12g/L, preferably 0.09g/L.

The mass ratio of the cetyltrimethylammonium bromide to SiC or Si ₃ N ₄ or Al ₂ O ₃ ceramic particles is 1:80˜1:100.

The pH value is 4.6-5.0, preferably 4.8.

Said adding the mixed liquids A and B, the added amount of the mixed liquid A is 10-14 g/L, and the added amount of the mixed liquid B is 6-15 g/L.

Described heating, its temperature is 85～90 ℃.

The present invention changes the Zeta potential on the particle surface through the selective adsorption of different particles to different surfactants. Specifically, the cationic fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I is adsorbed on the surface of PTFE particles, which increases the potential on the surface, increases the electrostatic repulsion between the particles, and avoids the particles due to gravity. caused subsidence. In addition, the increase in particle surface potential makes PTFE more easily adsorbed on the surface of the substrate under the action of electrostatic attraction, thereby increasing the amount of particle deposition. Similarly, the adsorption of cetyltrimethylammonium bromide also increases the surface potential of SiC particles, increases the electrostatic repulsion between SiC particles, avoids particle sedimentation, and also makes SiC easily adsorbed on the surface of the substrate, increasing the amount of deposition. In short, the addition of surfactant can increase the amount of particle deposition and improve the uniform distribution of particles, and finally achieve the purpose of improving the wear resistance and friction reduction performance of the composite coating. Of course, the compounding amount of particles is for the purpose of improving the performance of the coating, if too much is added, the stress of the coating will increase and the bonding force will decrease. If the particle content is too small, the effect of improving the performance of the coating cannot be achieved. Repeated tests show that the addition amount of PTFE emulsion is 10-14g/L, and the addition amount of ceramic particles is 6-15g/L, which is more appropriate.

The self-lubricating chemical composite coating obtained by the invention has a large deposition amount of two kinds of particles and is evenly distributed, and has good wear resistance and friction reduction performance under high load and high speed. The method involved in the invention is easy to operate and low in cost, realizes uniform deposition of particles through the action of the surfactant, obtains a self-lubricating chemical composite coating, and enables the material to have a wider application range.

Detailed ways

Example 1

1. Dissolve 0.33g of fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I in deionized water and mix it with 14g of PTFE emulsion; dissolve 0.07g of hexadecyltrimethylammonium bromide in deionized water Finally mix with 8gSiC.

2. Preparation of electroless nickel plating solution: The composition of the electroless plating solution includes nickel sulfate, sodium hypophosphite, lactic acid, sodium acetate, and acryl thiourea. Add nickel sulfate 20g/L and lactic acid 33mL/L to the plating tank in sequence at room temperature , sodium acetate 15g/L, sodium hypophosphite 25g/L and propenyl thiourea 1.5mg/L, adjust the pH value to 4.6 with sodium hydroxide.

3. Chemical composite plating: Add the two mixed solutions described in 1 to the acidic plating solution prepared in step 2, heat the plating solution to 90°C, and keep stirring during the plating process to obtain a self-lubricating chemical composite plating layer.

The phosphorus content of the coating obtained in this embodiment is 8.7%wt, the PTFE content is 5.3%wt, and the SiC content is 6%wt. The microhardness of the coating in the as-plated state is HV ₅₀ 482, which is significantly higher than that of the electroless Ni-P-PTFE composite coating obtained under the same conditions. Under a high load of 150N and a rotational speed of 100r/min, the friction coefficient of the composite coating is only 0.15, and its volumetric wear rate is 8.77×10 ^-5 mm ³ ·m ^-1 The Ni-P-PTFE composite coating has been worn through and the substrate has been damaged. The wear resistance of the Ni-P-PTFE-SiC composite coating was further improved by heat treatment at 400℃ for 1 hr.

Example 2

1. Dissolve 0.18g of fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I in deionized water and mix it with 10g of PTFE emulsion; dissolve 0.07g of hexadecyltrimethylammonium bromide in deionized water Finally, mix with 10g Al ₂ O ₃ ceramic particles.

2. Preparation of electroless nickel plating solution: its components include nickel sulfate, sodium hypophosphite, lactic acid, sodium acetate, and acryl thiourea. Add nickel sulfate 20g/L and sodium citrate 25g/L to the plating tank in sequence at room temperature , sodium hypophosphite 30g/L and propylene thiourea 1.5mg/L, adjust the pH value to 4.8 with sodium hydroxide.

3. Chemical composite plating: Add the two mixed solutions described in 1 to the acidic plating solution prepared in step 2, heat the plating solution to 90°C, and keep stirring during the plating process to obtain a self-lubricating chemical composite plating layer.

The content of phosphorus in the surface nanocomposite obtained in this example is 9.0%wt, the content of PTFE is 4%wt, and the content of micron alumina is 5.2%wt. Under a high load of 150N and a rotational speed of 100r/min, the friction coefficient of the composite coating is only 0.17, and its volume wear rate is 8.31×10 ^-5 mm ³ ·m ^-1 .

Example 3

1. Dissolve 0.27g of fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I in deionized water and mix it with 12.5g of PTFE emulsion; After dissolving, mix with 9g Si ₃ N ₄ .

2. Preparation of electroless nickel plating solution: its components include nickel sulfate, sodium hypophosphite, lactic acid, sodium acetate, and acryl thiourea. Add nickel sulfate 25g/L, lactic acid 33mL/L, and acetic acid to the plating tank in sequence at room temperature. Sodium 15g/L, sodium hypophosphite 25g/L and propylene thiourea 1.5mg/L, adjust the pH value to 5.0 with sodium hydroxide.

3. Chemical composite plating: Add the two mixed solutions described in 1 to the acidic plating solution prepared in step 2, heat the plating solution to 90°C, and keep stirring during the plating process to obtain a self-lubricating chemical composite plating layer.

The content of phosphorus in the surface self-lubricating composite material obtained in this embodiment is 8.9%wt, the content of PTFE is 4.2%wt, and the content of micron silicon nitride particles is 5.0%wt. Under the high load of 150N and the rotational speed of 100r/min, the friction coefficient of the composite coating is only 0.17 and the volumetric wear rate is 8.5×10 ^-5 mm ³ ·m ^-1 when it is rubbed against heat-treated 45# carbon steel.

Claims (10)

1. a preparation method of self-lubricating chemical composite coating, is characterized in that, concrete steps are as follows: 1) First, dissolve the fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I used in the foam fire extinguishing agent and the PTFE emulsion to obtain the mixed solution A, and then add cetyltrimethylammonium bromide and SiC Or Si ₃ N ₄ or Al ₂ O ₃ ceramic particles were dissolved to obtain the mixed solution B; 2) Plating solution preparation: the electroless nickel alloy plating solution is an acidic electroless nickel plating solution, namely: add nickel sulfate, lactic acid, sodium acetate, sodium hypophosphite, acryl thiourea, and hydrogen to the plating tank in sequence at room temperature. Sodium oxide adjusts the pH value; 3) Chemical composite plating: the chemical composite plating process is adopted, that is, the mixed solutions A and B are added to the acidic plating solution prepared in step 2, the plating solution is heated, and the plating process requires constant stirring to obtain a self-lubricating chemical composite plating layer. 2. the preparation method of self-lubricating chemical composite coating according to claim 1 is characterized in that, described fluorocarbon surfactant C ₂₀ H ₂₀ F ₂₃ N ₂ O ₄ I and PTFE emulsion, its mass ratio is 1 :30～1:55. 3. The preparation method of self-lubricating chemical composite coating according to claim 1, characterized in that, the concentration of said cetyltrimethylammonium bromide is 0.07～0.12g/L. 4. the preparation method of self-lubricating chemical composite coating according to claim 3 is characterized in that, described cetyltrimethylammonium bromide, its concentration is further limited to 0.09g/L. 5. the preparation method of self-lubricating chemical composite coating according to claim 1 is characterized in that, described hexadecyltrimethylammonium bromide and SiC or Si ₃ N ₄ or Al ₂ O ₃ ceramic particles, The mass ratio thereof is 1:80 to 1:100. 6. The preparation method of self-lubricating chemical composite coating according to claim 1, characterized in that, adding nickel sulfate 18～30g/L, lactic acid 15～35ml/L, acetic acid to the plating tank successively at room temperature Sodium 10-20g/L, sodium hypophosphite 15-40g/L, propenylthiourea 0.1-0.3mg/L. 7. The method for preparing the self-lubricating chemical composite coating according to claim 6, characterized in that the pH value is 4.6-5.0. 8. The preparation method of self-lubricating chemical composite coating according to claim 1, characterized in that, the pH value is further limited to 4.8. 9. The preparation method of self-lubricating chemical composite coating according to claim 1, characterized in that, the addition of mixed solution A and B, the addition of mixed solution A is 10 ~ 14g/L, the addition of mixed solution B The amount is 6-15g/L. 10. The method for preparing self-lubricating chemical composite coating according to claim 1, characterized in that the temperature of the heating is 85-90°C.