CN102744399A - Dispersing method for nanometer copper powder aggregates - Google Patents

Abstract

The method for dispersing the nano-copper powder agglomerates comprises the following steps: first, the nano-copper powder prepared by the physical method is corroded by nitric acid and sulfuric acid, and at the same time, the PVP surface is coated and modified, and the obtained copper powder is dispersed in white oil with an ultrasonic pulverizer, When dispersing, add a certain amount of diisooctyl succinate to white oil. The method can refine the particle size of the nano-copper powder prepared by the physical method, and at the same time, wrapping can prevent the oxidation and agglomeration of the nano-copper, and is easier to disperse in the lubricating oil medium.

Description

Dispersion Method of Nano Copper Powder Agglomerates

technical field

The patent belongs to the technical field of nano powder dispersion, in particular to a method for dispersing nano copper powder agglomerates in lubricating oil medium.

Background technique

As a lubricating oil additive, nano-copper powder has broad application prospects in improving engine lubrication, reducing friction and wear, improving engine power performance, reducing pollution and prolonging life. To give full play to the special properties of nanoparticles, the prepared copper powder must be a single-particle nanopowder as much as possible. However, due to the extremely high activity of metal nanoparticles and the existence of various adsorption forces between nanoparticles, the gap between nanoparticles It is easy to form agglomerates, and the nano-metal powder generally referred to is actually its agglomerates. Therefore, solving the dispersion problem of metal nanoaggregates is one of the key technologies for its popularization and application.

Judging from the current research, the methods to improve the dispersion stability of nanomaterials in lubricating oil mainly include the following aspects: (1) Ultrasonic dispersion; ultrasonic dispersion is to directly place the nanoparticle suspension to be treated in an ultrasonic field , treated with ultrasonic waves of appropriate frequency and power, the intensity is very high. The mechanism of ultrasonic dispersion is related to cavitation. Cavitation can generate high temperature and high pressure locally on particles, accompanied by huge impact force and micro-jet flow, which have micro-crushing effect and break up aggregates. (2) Shear emulsification: it mainly breaks aggregates by means of external shear, impact and stretching, so as to realize the crushing of particles in the medium. (3) Ball milling: Ball milling is currently the most commonly used method for dispersing ultrafine powders. The ball-to-ball impact generated by the high-frequency vibration of the grinding body is used to pulverize powder particles. However, during the grinding process, due to the impact and grinding between the ball and the ball, the ball and the cylinder, and the ball and the material, the ball mill cylinder and the ball itself are worn and become impurities. In addition, the size of ultrafine particles formed by ball milling is also limited. However, the above three methods cannot break the hard agglomeration of nano-copper powder produced by metal bonding.

Contents of the invention

The object of the present invention is to provide a method for dispersing nanometer copper powder agglomerates.

The present invention is a kind of dispersing method of nano-copper powder agglomerate , corrodes copper powder agglomerate with nitric acid, and its steps are:

(1) Add nano-copper powder aggregates and polyvinylpyrrolidone to 0.1mol/L~1mol/L nitric acid aqueous solution according to the solid-to-liquid ratio g/ml of 1:50~1:10 and 1:250~1:1000 respectively Medium, react for 5~20 minutes;

(2) Use a centrifuge to separate the solid powder 1, wash the separated copper powder with deionized water, remove the nitrate ions in the solution, and then add it to a 0.5mol/L~4.0mol/L dilute sulfuric acid solution , react for 5-20 minutes, wash again with deionized water, remove sulfate ions in the solution, and centrifuge to obtain solid powder;

(3) washing the solid powder 2 with absolute ethanol, and drying to obtain nano-copper powder;

(4) Add the nano-copper powder agglomerates to the white oil according to the solid-to-liquid ratio g/ml of 1:1000~1:100, and add 0.1~0.8ml of diisooctyl succinate at the same time, and use an ultrasonic pulverizer to process dispersion.

The advantage of the present invention is that nitric acid and sulfuric acid corrosion can not only achieve the purpose of impurity removal, but also refine the particles. With the increase of corrosion degree, the effect first becomes better and then worsens. If the degree of corrosion is too low, the purpose of refining nano-copper powder particles cannot be achieved, and if the degree of corrosion is too high, a part of the fine-grained nano-copper powder will be completely reacted by nitric acid, thereby failing to achieve the purpose of refining nano-copper powder particles. When the level is 2-30% of the mass of copper powder, the effect is the best. The method of the invention is simple, easy to operate, easy to grasp, obvious in effect and easy to industrialized production.

Description of drawings

Figure 1 is a schematic diagram of nano-copper powder corrosion wrapping, Figure 2 is an untreated TEM image of nano-copper powder prepared by physical methods, Figure 3 is a TEM image of nano-copper powders prepared by physical methods after corrosion surface modification, and Figure 4 is untreated Infrared spectrum diagram of copper powder, Figure 5 is the infrared spectrum diagram of PVP and copper powder after treatment, Figure 6 is the XRD diagram of untreated nano-copper powder, Figure 7 is the XRD diagram of copper powder after nitric acid treatment and corrosion of 20% wrapped PVP , Figure 8 is the XRD pattern of copper powder after sulfuric acid treatment, Figure 9 is the stability diagram of untreated nano-copper powder in white oil, Figure 10 is the stability diagram of modified nano-copper powder in white oil, and Figure 11 is The stability diagram of copper powder in white oil on the first day after treatment, Figure 12 is the stability diagram of copper powder in white oil on day 3 after treatment, and Figure 13 is the stability diagram of copper powder in white oil on day 8 after treatment Stability diagram in oil, Fig. 14 is the stability diagram of copper powder in white oil on the 30th day after treatment, and Fig. 15 is the stability diagram of copper powder in white oil on day 45 after treatment. the

Detailed ways

Example 1:

Take by weighing the nano-copper powder aggregate prepared by the physical method of 1g, according to the reaction equation of copper and dilute nitric acid:

CuO+2HNO ₃ =Cu(NO ₃ ) ₂ +H ₂ O

3HNO ₃ +8Cu=3Cu(NO ₃ ) ₂ +2NO ₂ +4H ₂ O

H ₂ O+Cu+Cu(NO ₃ ) ₂ =Cu ₂ O+2HNO ₃

50 mg of nano-copper powder was corroded, and the amount of concentrated nitric acid used was calculated to be 0.2 ml. The concentrated nitric acid was diluted to 10 ml, and 40 mg of PVP was weighed. Proceed as follows:

First add 40mg of PVP to the dilute nitric acid solution, stir well to dissolve it completely, and obtain the prepared corrosion modification solution;

( 1) Add 1g of copper powder to the prepared solution and stir to make the reaction complete;

(2) Pour all the liquid and remaining copper powder into a centrifuge tube, centrifuge for 10 minutes, pour off the upper liquid, add distilled water for further centrifugal washing, and repeat three times until the upper liquid is colorless. The copper powder is completely settled at the bottom of the centrifuge tube, and the upper liquid is poured off;

( 3) Take out the copper powder in the test tube, put it into a dilute sulfuric acid solution with a mass fraction of 5%, react for 10 minutes, centrifuge and wash, and the following chemical reaction occurs: Cu ₂ O+H ₂ SO ₄ ＝Cu+CuSO ₄ +H ₂ O;

(4) drying the centrifuged copper powder to obtain corroded nano copper powder;

(5) Disperse to obtain nano-copper powder, the specific method:

In order to ensure that the newly obtained nano-copper powder can be dispersed in the white oil in the form of single particles, an ultrasonic pulverizer is used for dispersion, the ultrasonic interval is 2s, the ultrasonic time is 40min, and the concentration of copper powder in the white oil is 1.2mg/ml. In order to make the dispersion time longer, add diisooctyl succinate to the white oil during ultrasonication, and the volume ratio of white oil to white oil is 1:50. Complete precipitation occurred after 30 days of dispersion.

Example 2:

Take by weighing the nano-copper powder aggregate prepared by the physical method of 1g, corrode the nano-copper powder of 100mg according to the steps shown in implementation example 1, calculate the amount of the concentrated nitric acid used to be 0.28ml, dilute the concentrated nitric acid to 10ml, Weigh 40mg of PVP. Prepare and disperse nanometer copper powder according to the step described in embodiment example 1. Complete precipitation occurred after 30 days of dispersion.

Example 3:

Take by weighing the nano-copper powder aggregate prepared by the physical method of 1g, according to the steps shown in implementation example 1, corrode the nano-copper powder of 200mg and calculate the amount of used concentrated nitric acid to be 0.57ml, dilute the concentrated nitric acid to 10ml, weigh Take 40mg of PVP. Prepare and disperse nanometer copper powder according to the step described in embodiment example 1.

It can be seen from Figure 7 that after the nitric acid corrosion of the nano-copper powder, a large amount of Cu ₂ O appeared in the composition, and the Cu ₂ O in the composition of the sulfuric acid corrosion was significantly reduced.

It can be seen from Figure 5 that after the corrosion modification of the nano-copper powder, the peak on the surface of the copper powder is basically consistent with the characteristic peak of the modifier PVP, which shows that the modified copper powder has the functional group of PVP, which can be compared with Figure 4 It can be seen that the unmodified copper powder does not contain the peak of PVP, which indicates that the bonding reaction between PVP and copper powder has occurred, and the encapsulation modification of nano copper powder has been realized.

Figures 9 to 15 record the stability of copper powder in white oil after treatment. It can be seen that copper powder is evenly dispersed in white oil after ultrasonic treatment. After three days, transparent white oil has appeared on the upper layer, indicating that some of them are large The granular copper powder has been precipitated. Eight days later, the transparent part has increased slightly. After one month, the transparent part has reached half of the whole. After one and a half months, the transparent part has slightly increased compared to one month.

Example 4:

Take by weighing the nano-copper powder aggregate prepared by the physical method of 1g, according to the steps shown in implementation example 1, corrode the nano-copper powder of 400mg and calculate the amount of used concentrated nitric acid to be 1.14ml, dilute the concentrated nitric acid to 10ml, weigh Take 40mg of PVP. Prepare and disperse nanometer copper powder according to the step described in embodiment example 1. Complete precipitation after dispersing for 30 days

Comparative example 1

Untreated nano-copper powder is dispersed, and the specific steps are as follows:

(1) Take 12mg of nano-copper powder and add it to the test tube;

(2) Take 10ml of white oil and add it to the test tube with nano-copper powder;

(3) Put it in an ultrasonic pulverizer for ultrasonication, after ultrasonication for 20 minutes, add diisooctyl succinate, and ultrasonication for another 20 minutes.

In order to ensure that the nano-copper powder can be fully affected by the ultrasonic wave, it can be stirred and shaken at intervals during the ultrasonic process. This is because the viscosity of the white oil is relatively large, and the range of action of the ultrasonic disperser in the white oil is small. Stirring and shaking can make some large particles float up, and the ultrasonic wave is more likely to act on the nano-copper powder. It can be seen from Figure 2 that there are some larger aggregate particles in the non-corrosion modified copper powder. The edges of these large particles are obviously connected together, while the modified copper powder (Figure 3) can clearly see the edges of the copper powder particles, and the particle size is also reduced.

As shown in Figures 9 to 12, by recording the stability of nano-copper powder in white oil, it can be seen that the untreated copper powder basically precipitated to the bottom of the test tube after 3 days of ultrasonic dispersion.

Example 5:

 Weigh 1g of nano-nickel powder, according to the reaction equation between nickel and dilute nitric acid:

3HNO ₃ +8Ni=3Ni(NO ₃ ) ₂ +2NO ₂ +4H ₂ O;

Corrosion 200mg of nano-nickel powder, calculate the amount of concentrated nitric acid used is 0.57ml, dilute the concentrated nitric acid into 10ml of dilute nitric acid, and weigh 40mg of PVP. Proceed as follows:

First add 40mg of PVP to the dilute nitric acid solution, stir well to dissolve it completely, and obtain the prepared corrosion modification solution;

( 1) Add 1g of nickel powder to the prepared solution and stir to make it react completely;

(2) Pour all the liquid and remaining nickel powder into a centrifuge tube, centrifuge for 10 minutes, pour off the upper liquid, add distilled water for further centrifugation and wash, repeat three times until the upper liquid is colorless. The nickel powder is completely deposited at the bottom of the centrifuge tube, and the upper liquid is poured off;

( 3) Take out the nickel powder in the test tube and dry it to obtain new nano-nickel powder;

(4) Decentralization, the method is as follows:

In order to ensure that the nano-nickel powder can be dispersed in the white oil in the form of single particles, an ultrasonic pulverizer is used for ultrasonic dispersion during dispersion. The ultrasonic time is 40 minutes, the interval is 2 seconds, and the concentration of the powder is 1.2 mg/ml. In order to make the dispersion time longer, add diisooctyl succinate to the white oil during ultrasonication, and the volume ratio of white oil to white oil is 1:50. the

Claims (4)

1. The method for dispersing the nano-copper powder agglomerates is to corrode the copper powder agglomerates with nitric acid, and the steps are: (1) Add nano-copper powder aggregates and polyvinylpyrrolidone to 0.1mol/L~1mol/L nitric acid aqueous solution according to the solid-to-liquid ratio g/ml of 1:50~1:10 and 1:250~1:1000 respectively Medium, react for 5~20 minutes; (2) Use a centrifuge to separate the solid powder 1, wash the separated copper powder with deionized water, remove the nitrate ions in the solution, and then add it to a 0.5mol/L~4.0mol/L dilute sulfuric acid solution , react for 5-20 minutes, wash again with deionized water, remove sulfate ions in the solution, and centrifuge to obtain solid powder; (3) washing the solid powder 2 with absolute ethanol, and drying to obtain nano-copper powder; (4) Add the nano-copper powder agglomerates to the white oil according to the solid-to-liquid ratio g/ml of 1:1000~1:100, and add 0.1~0.8ml of diisooctyl succinate at the same time, and use an ultrasonic pulverizer to process dispersion. 2. The method for dispersing the nano-copper powder agglomerates according to claim 1, wherein the nano-copper powder used is a nano-copper powder agglomerate prepared by a physical method. 3. The method for dispersing the nano-copper powder agglomerates according to claim 1, characterized in that the dispersing method is applicable to the nano-copper powder agglomerates prepared by other methods. 4. The dispersion method of nano copper powder agglomerates according to claim 1, characterized in that the dispersion method is suitable for the dispersion of nano nickel powder or nano iron powder agglomerates.

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