CN106929835A - Chemical plating fluid and use its method to SiC particulate Surface coating Ni P - Google Patents

Abstract

The present invention relates to a kind of electroless plating liquid, and it is used for coating Ni-P to the surface of SiC particle, and the present invention also relates to adopting this electroless plating liquid to the method for SiC particle surface coating Ni-P, and it comprises the following steps: 1) SiC surface cleaning treatment; 2) coarsening of SiC particles; 3) activation and sensitization of SiC particles; 4) preparation of chemical plating solution and plating; 5) post-chemical plating treatment. When the concentration of [Ni ²⁺ ] in the electroless plating solution is 0.25mol/L, the concentration of [NH ₄ ⁺ ] is 0.6mol/L, the ratio of the concentration of [Ni ²⁺ ]/[H ₂ PO ₂ ^‑ ] is 0.4, citric acid The SiC surface wrapping effect is the best when the concentration is 0.1mol/L, and trace amounts of lactic acid and thiourea. The invention fully coats SiC particles with nickel by electroless nickel plating solution, which solves the problems of low wettability of SiC particles and difficulty in compounding with metal liquid, and the chemical plating solution has low maintenance cost and long service life.

Description

Electroless plating solution and its method of coating Ni-P on the surface of SiC particles

technical field

The invention belongs to the technical field of surface treatment of micron particles, and in particular relates to an electroless plating solution for coating Ni-P on the surface of SiC particles. Method and SiC particles obtained therefrom.

Background technique

Traditional superalloys require a large grain size or even a single crystal. This is because the smaller the grain size of the alloy material, the larger the grain boundary area, and the easier the diffusion of atoms. Therefore, under the action of high temperature and stress, through the tilting of the grain Plastic deformation occurs with deformation, which accelerates the creep rate of the alloy material and shortens its high temperature durability. The ceramic particles with high melting point distributed in the grain boundary have obvious grain boundary pinning effect, which greatly reduces the diffusion speed of metal atoms along the grain boundary. At the same time, the grain boundary effectively hinders the movement of dislocations, improving the alloy material Compared with traditional coarse-grained superalloy materials, it has better high-temperature strength, stability and durability. Therefore, it has been proposed to combine the advantages of large-sized grains with ceramic particles into superalloys.

However, the wettability between ceramic particles and metal materials is not good. In order to solve this problem, a method of depositing a nickel layer on the surface of ceramic particles is usually adopted. At present, there are two main methods of depositing metal on the surface of ceramic particles, electroplating and electroless plating. Among them, electroplating requires an external DC power supply, which is expensive, while electroless nickel plating does not require an external DC power supply. It is an excellent surface treatment technology. It has been used in a certain range in many industrial sectors.

Specifically, the electroless plating method refers to the method of using a metal salt solution to reduce metal ions to metal under the action of a reducing agent to obtain a metal deposition layer on a plated piece with a catalytic surface. Electroless nickel plating has very good throwing ability, high binding force, simple process, low cost, and can metallize non-conductive substrates, and the electroless nickel plating layer has high hardness, wear resistance, corrosion resistance and other properties. Metal-coated ceramic particles refer to composite ceramic particles composed of a layer of heterogeneous metal coated on the surface of ceramic particles, which combines the excellent properties of the coating metal and core ceramics, and can combine the strength, toughness, and ease of processing of metal materials. and other characteristics combined with the high temperature resistance, wear resistance and corrosion resistance of ceramic materials.

There are four hypotheses on the deposition mechanism of electroless Ni-P alloys, namely atomic hydrogen theory, hydride transport theory, electrochemical theory and light base-nickel ion coordination theory. Among them, the theory of atomic hydrogen is highly recognized. According to this theory, in the process of electroless Ni-P alloy plating, the following process occurs:

The first step: the hypophosphite in the solution is dehydrogenated in the solution to generate phosphite ion, and at the same time, the nascent atomic hydrogen is released. The nascent atomic hydrogen is adsorbed on the catalytic surface to activate it, and the cationic nickel in the plating solution is reduced. , and deposit metallic nickel on the catalytic surface, the reaction formula is as follows:

H ₂ PO ₂ ^- +H ₂ O→HPO ₃ ^2- +2H ⁺ +[H] ^-

Ni ²⁺ +2[H] ^- →Ni+H ₂ ↑ (hydrogen evolution reaction).

Step 2: Part of the hypophosphite is reduced to elemental phosphorus by the hydride and enters the coating at the same time. The reaction formula is as follows:

2H ₂ PO ₂ ^- +6[H] ^- +4H ₂ O→2P+8OH ^- +5H ₂ ↑.

However, compared with the electroplating solution, the electroless nickel plating solution has the following problems: the conditions require higher precision, the balance of various chemical components, and the operable range of the process parameters are relatively narrow; the tolerance to pollutants is relatively poor, even ppm Level of heavy metal ions may cause coating performance deterioration or missing plating, stop plating; Considering the life of the electroless plating solution, compared with the electroplating solution, the stability of the mixed solution of electroless nickel plating is very poor, and the solution needs to be maintained and repaired. The adjustment work is more troublesome. This problem arises mainly because electroless nickel has no external force to initiate and help overcome any surface defects, the reaction is initiated by the surface conditions, i.e. heterogeneous surface autocatalytic reaction, unlike electroplating, which is powered by the outside world to drive the reaction.

Contents of the invention

In view of this, the inventor of the present invention wishes to provide a kind of new electroless plating solution, does not need complex maintenance technology and long service life in its use process, in addition, the inventor of the present invention also aims to provide a kind of SiC particle surface Activation and sensitization pretreatment activation and sensitization solution to solve the problem of low wettability of SiC particles and difficulty in compounding with metal liquid, and to achieve full coating of SiC particles with nickel-phosphorus.

In order to realize the above-mentioned purpose of the invention, the present invention adopts following technical scheme:

According to a specific embodiment of the present invention, an electroless plating solution is provided, which is used to coat the surface of SiC particles with Ni-P, which includes the following components: nickel sulfate hexahydrate, sodium hypophosphite, ammonium sulfate, Trisodium Citrate, as well as Lactic Acid and Thiourea.

The electroless plating solution according to an embodiment of the present invention, wherein, the concentration of the nickel sulfate hexahydrate is 0.05-0.25mol/L, the concentration of the sodium hypophosphite is 0.08-1.25mol/L, and the concentration of the ammonium sulfate 0.5-0.9 mol/L, the content of the trisodium citrate is 0.1-0.5 mol/L, and the lactic acid and thiourea are trace amounts.

The electroless plating solution according to an embodiment of the present invention, wherein the pH of the electroless plating solution is adjusted to be 8-10, and the temperature is 30-50 degrees Celsius.

The electroless plating solution according to an embodiment of the present invention, wherein, the concentration of the nickel sulfate hexahydrate is 0.25mol/L, the concentration of the sodium hypophosphite is 0.625mol/L, and the concentration of the ammonium sulfate is 0.6mol/L L, the content of the trisodium citrate is 0.1mol/L.

According to an embodiment of the present invention, there is no activation sensitization pretreatment, wherein the activation sensitization process is not implemented, as a comparative example, it proves the good effect of the activation sensitization solution.

According to a specific embodiment of the present invention, there is provided a method for coating the surface of SiC particles with Ni-P by using any one of the above-mentioned electroless plating solutions, which includes the following steps.

Step 1: SiC particle cleaning treatment

The SiC particles were cleaned by ultrasonic cleaning with anhydrous ethanol, NaOH solution and hydrochloric acid solution in sequence, and then the SiC particles were cleaned with deionized water to neutrality, and the pretreated SiC particles were obtained after filtration and drying.

Step 2: Coarsening treatment of SiC particles

Put the SiC particles obtained through the treatment in the first step into the roughening solution, and apply magnetic stirring to obtain the roughened SiC particles.

Step 3: SiC particle activation and sensitization treatment

Place the coarsened SiC particles obtained in step 2 in the activation and sensitization solution, place the reaction system in a water bath at 30-40°C, apply ultrasonic waves, and then let stand, precipitate, and wash with deionized water and filtered and dried to obtain activated and sensitized SiC particles.

Step 4: Electroless plating of SiC particles

Add 5 g of SiC particles activated and sensitized by step three into 250 mL of the electroless plating solution according to any one of claims 1 to 4, place the reaction system in a water bath at a constant temperature of 30-50 °C, and Apply magnetic stirring.

5) Subsequent processing

The reaction solution treated in the step 4 is left to settle, filtered, and dried at 80-90° C. for more than 10 hours to obtain SiC particles whose surface is coated with nickel.

The method for coating Ni-P on the surface of SiC particles according to an embodiment of the present invention, wherein, in the first step, the ultrasonic cleaning time of the absolute ethanol is 5-10min; the NaOH solution is 5 mass % NaOH solution, ultrasonic cleaning for 5-10min; the hydrochloric acid is 37% by mass of pure hydrochloric acid solution, ultrasonic cleaning for 5-10min, the SiC particles after alkali washing and acid washing are precipitated and filtered before deionized Washing with water until the SiC particles are neutral, and then precipitating to obtain SiC particles, and drying the SiC particles at 80-90° C. for more than 10 hours.

The method for coating Ni-P on the surface of SiC particles according to an embodiment of the present invention, wherein, in the second step, the roughening solution is 37% by mass of pure hydrochloric acid and deionized water in a volume ratio of 1 :1 prepared, the magnetic stirring time is 20min, after the stirring is completed, the reaction solution is left to stand, precipitated and filtered to obtain SiC particles, and the obtained SiC particles are washed and filtered with deionized water for 3 times to obtain coarse SiC particles.

According to the method of coating Ni-P on the surface of SiC particles according to an embodiment of the present invention, in the second step, 10-40 g of SiC particles are added corresponding to 300 mL of the roughening solution.

According to the method of coating Ni-P on the surface of SiC particles according to an embodiment of the present invention, in the step 3, the action time of the ultrasonic wave is 20 minutes, and after the reaction is completed, the reaction solution is left to stand, precipitated, and filtered, and the filtered SiC particles were washed three times with deionized water, and the cleaned SiC particles were dried at 80-90° C. for more than 10 hours to obtain activated SiC particles.

According to a method of coating Ni-P on the surface of SiC particles according to an embodiment of the present invention, the activation sensitization solution consists of the following:

Palladium dichloride 0.5g/L, stannous chloride dihydrate 30g/L, sodium chloride 160g/L, 37% by mass HCl 60mL/L.

Through the above technical solutions, the present invention mainly achieves the following technical effects:

(1) Compared with electroplating, no external DC power supply equipment is required, and the resulting coating is dense and has less pores; it can be plated on various substrates such as metals, non-metals, and semiconductors; it can be distributed by introducing distribution into brittle ceramics. Uniform metal phase to improve its fracture toughness; strong throwing ability, which can make the metal phase of the coated powder interconnected into a network.

(2) Compared with other electroless plating methods, this process has the following advantages: 1) The one-step activation and sensitization method is adopted for SiC surface treatment, which is simplified compared with the two-step activation and sensitization method widely used at present. After the traditional two-step process of sensitization and activation, it is difficult to remove the stannous ions remaining in the powder, which often has an adverse effect on the performance of the powder. The process is cumbersome, the operation is complicated, and the maintenance is difficult. Different from this, the activation and sensitization one-step method of the present invention has low cost and is easy to prepare raw materials. At the same time, the activation and sensitization solution contains chlorine salt (NaCl is an example) as a liquid stabilizer; 2) the traditional process ignores the selected plating solution The influence of hydrogen ions and hydroxide ions generated during the hydrolysis of the components on the pH of the plating solution, and the composition of the chemical plating solution is different. This process is fully aimed at the SiC surface under the condition of alkaline low temperature. The selection of each component of the electroless plating solution during electroless Ni-P plating is highly targeted.

Description of drawings

Figure 1(a) and Figure 1(b) are the SEM photos and EDS analysis results of the roughened SiC particles, respectively;

Figure 2(a) and Figure 2(b) are the SEM photos and EDS analysis of the activated and sensitized SiC particles, respectively;

Fig. 3 is the weight gain percentage change of each group of experiments;

Fig. 4 is the SEM photograph of SiC particle obtained in embodiment 1;

Fig. 5 is the detection result of the EDS of the particle that randomly selects SiC obtained in embodiment 1;

Fig. 6 is the SEM photograph of the SiC particle obtained in embodiment 2;

Fig. 7 is the EDS detection result of randomly selecting SiC particles obtained in Example 2;

Fig. 8 is the SEM photograph of the SiC particle obtained in embodiment 3;

Fig. 9 is the EDS detection result of randomly selecting SiC particles obtained in Example 3;

Fig. 10 is the SEM photo of the SiC particles obtained in Comparative Example 3;

FIG. 11 is the EDS detection result of randomly selected SiC particles obtained in Comparative Example 3.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The specific implementation steps of coating Ni-P on the surface of SiC particles in the present invention include cleaning treatment of SiC particles, roughening treatment of SiC particles, activation and sensitization treatment of SiC particles, chemical plating and post-chemical plating treatment.

1) Cleaning treatment of SiC particles

Use pickling + alkali washing to clean the original SiC particles to remove oil and dirt, then wash the SiC particles with deionized water to neutrality, filter and dry to obtain pretreated SiC particles, the specific process is as follows:

Quantitative SiC particles were taken, placed in absolute ethanol for ultrasonic cleaning for 5 min, filtered, placed in 5 mass % NaOH solution for ultrasonic cleaning for 5 min, filtered, placed in 37 mass % pure hydrochloric acid solution for ultrasonic cleaning for 5 min, filtered, and used Wash with ionized water until neutral, place in a blast drying oven, and dry at 80°C for later use;

2) Coarsening treatment of SiC particles

Use hydrochloric acid and deionized water to make a roughening solution, then put 10-40g of cleaned SiC powder into 300mL roughening solution and magnetically stir to obtain roughened SiC particles. The specific process is as follows:

Take 20g of SiC particles after cleaning treatment, put them in 300mL roughening solution prepared by 37% by mass of pure hydrochloric acid and deionized water at a volume ratio of 1:1; place, precipitate and filter, place in a blast drying oven at 80°C, and dry for 10 hours for use; Figure 1(a) and Figure 1(b) are the SEM photos and EDS analysis of SiC particles after coarsening, and Table 1 is The EDS analysis results of the roughened SiC particles show that the surface of the SiC particles is relatively smooth from the picture after roughening.

Table 1: EDS analysis results of coarsened SiC particles

element wt% atomic percentage C 62.16 79.34 Si 37.84 20.66 Total 100.00 100.00

3) Activation and sensitization treatment of SiC particles

The roughened SiC particles were activated and sensitized by one-step activation and sensitization method.

_The specific process of preparing activation and sensitization is as follows: 0.25g PdCl is added to 30mL of 37 mass% HCl solution, and the volume is adjusted to about 50mL with deionized water to obtain solution A; then 80g NaCl is dissolved in 250mL deionized water to obtain Solution B; then mix solution A and B, and stir with a glass rod for 5 minutes to obtain solution C; then dissolve 15g SnCl ₂ ·2H ₂ O in 150mL deionized water to obtain solution D; then add solution D while stirring Add solution C to obtain dark green solution E; finally add deionized water and use a volumetric flask to set the volume to 500mL to obtain a dark green activation solution. Take the cleaned and coarsened SiC particles and place them in the activation sensitization solution, the addition amount is 20-40g/L, and put the reaction system in a water bath at 30-40°C, and apply ultrasonic waves for 20min. After the reaction, The reaction solution was left to stand, precipitated, washed three times with deionized water, filtered, and dried in an oven at 80-90° C. for more than 10 hours to obtain activated and sensitized SiC particles.

Figure 2(a) and Figure 2(b) are the SEM photos and EDS analysis of SiC particles after activation and sensitization, respectively. Table 2 is the EDS analysis results of SiC particles after activation and sensitization. As can be seen from Figure 2, the SiC particle surface comparison It is rough and contains palladium ions at the same time. See Table 2 for the specific content of each element.

Table 2: EDS analysis results of SiC particles after activation and sensitization

element wt% atomic percentage C 43.48 64.54 Si 55.63 35.31 PD 0.89 0.15 Total 100.00 100.00

4) Chemical plating

Configure the chemical plating solution: configure the concentration of nickel sulfate hexahydrate to be 0.05-0.25mol/L, the concentration of sodium hypophosphite to be 0.08-1.25mol/L, the concentration of ammonium sulfate to be 0.5-0.9mol/L, and the content of trisodium citrate to be 0.1-0.5mol/L, and traces of lactic acid and thiourea, dilute to 250mL solution with deionized water, then adjust the pH of the solution to 8-10, and place 5g of SiC particles that have been activated and sensitized in the electroless plating Place the reaction system in a water bath with a constant temperature of 30-50°C in 250 mL of liquid solution, and stir it magnetically for 60 minutes to obtain a reaction solution after plating.

In order to specifically discuss the content of each component with an orthogonal test, select 6 factors: [Ni ²⁺ ] concentration, [Ni ^{2 +} ]/[H ₂ PO ₂ ^- ] concentration, [NH ₄ ⁺ ] concentration, citric acid Concentration, pH, temperature, and test level select 5 levels, and design an orthogonal test design table, as shown in Table 3 below.

Table 3: Orthogonal Experimental Design Table for Electroless Plating

Design 25 orthogonal experiments, the percentage of weight gain before and after electroless plating m%=(mm _o )/m _o (m represents the weight of SiC powder after plating, m _o represents the weight of original SiC added, 5.0000g) to SiC The degree of Ni-P plating on the particle surface was evaluated, and the results are shown in Fig. 3 as the weight gain percentage change of each group of experiments.

Embodiment 1 (orthogonal experiment 20)

Configure chemical plating solution 250mL, the specific composition of this chemical plating solution is that the concentration of nickel sulfate hexahydrate is 0.20mol/L, the concentration of sodium hypophosphite is 0.333mol/L, the concentration of ammonium sulfate is 0.7mol/L, and the concentration of trisodium citrate is 0.20mol/L. The content is 0.1mol/L, and traces of lactic acid and thiourea, and dilute to 250mL solution with deionized water.

Take 5 g of activated and sensitized SiC particles and place them in the plating solution (thus, the content of SiC particles in the plating solution is 20 g/L), adjust the pH of the solution to 9.5, and place the reaction system in a water bath at a constant temperature of 40°C. , and reacted under magnetic stirring for 60 minutes. After the reaction was completed, the plating solution was left to settle, filtered, placed in a blast drying oven at 80°C, and dried for 10 hours to obtain nickel-coated SiC particles; The SEM photo of the SiC particles after plating shows that the surface of the SiC particles after plating is evenly distributed with point-shaped nickel particles, and it cannot completely cover the SiC particles. It can be seen from Figure 2 that most of the particle surfaces are exposed.

The nickel-coated SiC particles obtained in Example 1 were randomly selected under a scanning electron microscope at a magnification of 500× for energy spectrum detection. Figure 5 and Table 4 are the EDS detection results of the SiC particles after plating in Example 1, wherein, except for C , Si, P with a mass fraction of 1.36% exists, and Ni with a mass fraction of 34.00% is attached to the particle surface.

Table 4: EDS detection results of SiC particles after plating in Example 1

element wt% atomic percentage C 7.62 18.92 o 2.46 4.59 Si 53.83 57.20 P 2.08 2.01 Ni 34.00 17.28 Total 100.00 100.00

Embodiment 2 (orthogonal experiment 16)

Configure 250mL of chemical plating solution, the composition of which is 0.20mol/L of nickel sulfate hexahydrate, 1.0mol/L of sodium hypophosphite, 0.8mol/L of ammonium sulfate, and 0.8mol/L of trisodium citrate. 0.2mol/L, and traces of lactic acid and thiourea, dilute to 250mL solution with deionized water.

Take 5g of activated and sensitized SiC particles and place them in the prepared plating solution (thus, the content of SiC particles in the plating solution is 20g/L), adjust the pH of the solution to 10, and place the reaction system in a water bath at 40°C React in a constant temperature water bath for 60 minutes under magnetic stirring. After the reaction, the plating solution is left to settle, filtered, and dried in a blast drying oven at 80°C for 10 hours to obtain nickel-coated SiC particles. Fig. 6 is a SEM photo of SiC particles after plating in Example 2. Cellular nickel particles are evenly distributed on the surface of SiC particles after plating, which can completely cover SiC particles.

The nickel-coated SiC particles obtained in Example 2 were randomly selected under a scanning electron microscope at a power of 500× for energy spectrum detection. Figure 7 and Table 5 are the EDS detection results of the SiC particles after plating in Example 2, wherein, except C , Si, P with a mass fraction of 2.16% exists, and Ni with a mass fraction of 36.50% is attached to the particle surface.

Table 5: EDS detection results of SiC particles after plating in Example 2

element wt% atomic percentage C 28.25 54.16 o 4.48 6.46 Si 28.61 23.46 P 2.16 1.60 Ni 36.50 14.32 Total 100.00 100.00

Embodiment 3 (orthogonal experiment 23)

Configure chemical plating solution 250mL, the composition of this chemical plating solution is that the concentration of nickel sulfate hexahydrate is 0.25mol/L, the concentration of sodium hypophosphite is 0.625mol/L, the concentration of ammonium sulfate is 0.6mol/L, and the concentration of trisodium citrate is 0.25mol/L. The content is 0.1mol/L, and traces of lactic acid and thiourea, and dilute to 250mL solution with deionized water.

Take 5g of activated and sensitized SiC particles and place them in the prepared plating solution (thus, the content of SiC particles in the plating solution is 20g/L), adjust the pH of the solution to 10, and place the reaction system in a water bath at 45°C React in a constant temperature water bath for 60 minutes under magnetic stirring. After the reaction, the plating solution is left to settle, filtered, and dried in a blast drying oven at 80°C for 10 hours to obtain nickel-coated SiC particles. During the experiment, the reaction was violent, and black flocculent Ni was formed. Figure 8 is the SEM photo of the SiC particles after plating in Example 3. Cellular nickel particles are evenly distributed on the surface of the SiC particles after plating, and the SiC particles are completely covered.

The nickel-coated SiC particles obtained in Example 3 were randomly selected under a scanning electron microscope at a power of 500× for energy spectrum detection. Figure 9 and Table 6 are the EDS detection results of the SiC particles after plating in Example 3, wherein, except C , besides Si, there is 2.65% of P in mass fraction, and 53.26% of Ni in mass fraction is attached to the particle surface.

Table 6: EDS detection results of SiC particles after plating in Example 3

element wt% atomic percentage C 17.87 42.37 o 3.64 6.47 Si 22.58 22.89 P 2.65 2.43 Ni 53.26 25.83 Total 100.00 100.00

In addition, in order to explore the influence of the activation sensitization process on the electroless plating effect, the SiC particles without activation sensitization were subjected to electroless Ni-P plating in Comparative Example 3.

Comparative example 3

Except not carrying out SiC pretreatment and not carrying out activation sensitization, carry out the processing identical with embodiment 3, its specific steps are as follows:

1) Take quantitative SiC particles, place them in absolute ethanol for ultrasonic cleaning for 10 minutes, and after filtering, place them in 5 mass % NaOH solution for ultrasonic cleaning for 10 minutes, filter, place them in 37 mass % hydrochloric acid solution for ultrasonic cleaning for 10 minutes, filter, and use Wash with ionized water until neutral, place in a blast drying oven, and dry at 80°C for later use;

2) Take 20g of cleaned SiC particles and place them in 300mL roughening solution prepared by 37 mass% hydrochloric acid and deionized water at a volume ratio of 1:1; place, precipitate and filter, and dry in a blast drying oven at 80°C for 10 hours for later use;

3) Configure 250mL of chemical plating solution, the composition of which is 0.25mol/L of nickel sulfate hexahydrate, 0.625mol/L of sodium hypophosphite, 0.6mol/L of ammonium sulfate, and 0.6mol/L of trisodium citrate. The content of 0.1mol/L, and traces of lactic acid and thiourea, dilute to 250mL solution with deionized water. Take 5g of unactivated and sensitized SiC particles and place them in the prepared plating solution (that is, the content of SiC particles is 20g/L), adjust the pH of the solution to 10, and place the reaction system in a water bath with a constant temperature of 45°C. Stir and react for 60 minutes. After the reaction is over, let the plating solution stand for precipitation, filter, and place in a blast drying oven at 80°C for 10 hours to dry.

Figure 10 is the SEM photo of the SiC particles after plating in Comparative Example 3; Figure 11 and Table 7 are the EDS detection results of the SiC particles after plating in Comparative Example 3 at a random selection of 500× magnification by the scanning electron microscope. In Comparative Example 3, the sample prepared when the pH was 10, according to the SEM results, the morphology of Ni changed, and the distribution was uneven, and the SiC could not be completely coated. The EDS result of random selection shows that the mass fraction of Ni is only 19.60%. It can be seen that the activation sensitization is an indispensable important step, and the activation sensitization of the present invention plays an important role in promoting the electroless nickel plating.

Table 7: EDS detection results of SiC particles after plating in Comparative Example 3

element wt% atomic percentage C 33.52 57.00 o 4.04 5.15 Si 41.01 29.82 P 1.83 1.21 Ni 19.60 6.82 Total 100.00 100.00

Combined with the analysis of Examples 1 to 3 and Comparative Example 3, it can be seen that it is very important to pre-treat the original SiC. At the same time, the concentration of nickel sulfate hexahydrate is 0.25mol/L, the concentration of sodium hypophosphite is 0.625mol/L, and the concentration of ammonium sulfate is 0.625mol/L. 0.6mol/L, the content of trisodium citrate is 0.1mol/L, and traces of lactic acid and thiourea, the volume is made to 250mL solution with deionized water, and 20g/L of activated and sensitized SiC particles are placed in the preparation In a good plating solution, adjust the pH of the solution to 10, place the reaction system in a water bath at a constant temperature of 45°C, and stir it with a magnetic force to obtain a reaction solution after plating. The coating effect on the SiC surface is the best.

That is, when the concentration of [Ni ²⁺ ] in the electroless plating solution is 0.25 mol/L, the concentration of [NH ₄ ⁺ ] is 0.6 mol/L, the ratio of the concentration of [Ni ²⁺ ]/[H ₂ PO ₂ ^- ] is 0.4, When the concentration of citric acid is 0.1mol/L, as well as trace amounts of lactic acid and thiourea, the coating effect of SiC surface is the best. Under other conditions, although Ni achieves partial coating on the surface of SiC particles, the exposed SiC surface has high surface energy and still has the disadvantage of poor wettability. As a strengthening phase, it cannot achieve a good interface bond with the matrix metal. At the same time, the activation sensitization plays an important role in the Ni-P plating on the SiC surface.

5) Electroless plating post-treatment

The reaction solution after plating is left to settle, filtered, and dried in a blast drying oven at 80-90° C. for more than 10 hours to obtain SiC particles whose surface is coated with nickel.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the implementation scope of the present invention; if it does not depart from the spirit and scope of the present invention, any modification or equivalent replacement of the present invention shall be covered by the claims of the present invention. within the scope of protection.

Claims (10)

1. an electroless plating solution, which is used to carry out the surface coating of Ni-P to SiC particles, is characterized in that, comprises following composition: Nickel sulfate hexahydrate, sodium hypophosphite, ammonium sulfate, trisodium citrate, as well as lactic acid and thiourea. 2. chemical plating solution according to claim 1, is characterized in that, described nickel sulfate hexahydrate concentration is 0.05-0.25mol/L, and the concentration of described sodium hypophosphite is 0.08-1.25mol/L, and described The ammonium sulfate concentration is 0.5-0.9 mol/L, the trisodium citrate content is 0.1-0.5 mol/L, and the lactic acid and thiourea are trace amounts. 3. The chemical plating solution according to claim 1 or 2, characterized in that the pH of the chemical plating solution is adjusted to be 8-10, and the temperature is 30-50°C. 4. the electroless plating solution according to claim 1 or 2, is characterized in that, described nickel sulfate hexahydrate concentration is 0.25mol/L, and the concentration of described sodium hypophosphite is 0.625mol/L, and described ammonium sulfate The concentration is 0.6 mol/L, and the content of the trisodium citrate is 0.1 mol/L. 5. A method for coating Ni-P on the surface of SiC particles using the electroless plating solution according to any one of claims 1 to 4, characterized in that, comprising the steps of: Step 1: SiC particle cleaning treatment Clean the SiC particles in sequence with anhydrous ethanol, NaOH solution and hydrochloric acid solution ultrasonic cleaning, then clean the SiC particles with deionized water until neutral, filter and dry to obtain pretreated SiC particles; Step 2: Coarsening treatment of SiC particles Put the SiC particles obtained through the treatment in the first step into the roughening solution, and apply magnetic stirring to obtain the roughened SiC particles; Step 3: SiC particle activation and sensitization treatment Place the coarsened SiC particles obtained in step 2 in the activation and sensitization solution, place the reaction system in a water bath at 30-40°C, apply ultrasonic waves, and then let stand, precipitate, and wash with deionized water and filtered and dried to obtain activated and sensitized SiC particles; Step 4: Electroless plating of SiC particles Add 5 g of SiC particles activated and sensitized by step three into 250 mL of the electroless plating solution according to any one of claims 1 to 4, place the reaction system in a water bath at a constant temperature of 30-50 °C, and Apply magnetic stirring; 5) Subsequent processing The reaction solution treated in the step 4 is left to settle, filtered, and dried at 80-90° C. for more than 10 hours to obtain SiC particles whose surface is coated with nickel. 6. The method according to claim 5, characterized in that, in the step one, the ultrasonic cleaning time of the dehydrated alcohol is 5-10min; the NaOH solution is 5% by mass of NaOH solution, ultrasonic cleaning 5-10min; the hydrochloric acid is a 37% by mass pure hydrochloric acid solution, and ultrasonically cleaned for 5-10min, the SiC particles after alkali washing and pickling treatment are precipitated and filtered, and then washed with deionized water until the SiC particles are medium After that, SiC particles are precipitated, and the SiC particles are dried at 80-90° C. for more than 10 hours. 7. The method according to claim 5, characterized in that, in the step 2, the roughened solution is formulated with 37% by mass of pure hydrochloric acid and deionized water at a volume ratio of 1:1, the The above-mentioned magnetic stirring time is 20 min. After the stirring is completed, the reaction solution is left to stand, precipitated and filtered to obtain SiC particles, and the obtained SiC particles are washed and filtered with deionized water for 3 times to obtain coarse SiC particles. 8. The method according to claim 5, characterized in that, in the second step, 10-40 g of SiC particles are added corresponding to 300 mL of the roughening solution. 9. The method for coating nickel on the surface of a SiC particle according to claim 5, characterized in that, in the step 3, the action time of the ultrasonic wave is 20min, and after the reaction finishes, the reaction solution is left to stand, Precipitate and filter, wash the filtered SiC particles with deionized water three times, and dry the cleaned SiC particles at 80-90° C. for more than 10 hours to obtain activated SiC particles. 10. The method according to claim 5, characterized in that, the activation and sensitization solution consists of the following: Palladium dichloride 0.5g/L, stannous chloride dihydrate 30g/L, sodium chloride 160g/L, 37% by mass HCl 60mL/L.