Application of nano copper in cutting fluid

Abstract

The present invention provides an application of nano copper in a cutting fluid. The nano copper is self-dispersible nano copper with an organic long-carbon chain, wherein the surface of copper metal is coated with a long carbon chain organic matter, and the long chain organic matter is dialkyl dithiophosphoric acid (HDDP) and a derivative thereof. In the present invention, the nano copper substitutes functional additives which comprises one or more of a preservative, an anti-rust agent, a sterilizing agent, a compression-resisting agent and a lubricant to solve the technical problems of the existing fluid in the prior art being unable to simultaneously have efficient anti-corrosion, anti-rust, compression-resistant, lubricating and sterilizing properties as well as the variety, the relatively high amount, the high cost and the limited selection of added additives.

Claims

1. An application of nano copper in a cutting fluid, wherein the nano copper is self-dispersible nano copper with an organic long-chain hydrocarbon having 8 carbon atoms or higher, wherein the nano copper is a copper metal surface coated with a long-carbon chain organic matter; the long-chain hydrocarbon having 8 carbon atoms or higher organic matter is dialkyldithiophosphate (HDDP) and a derivative thereof; and the cutting fluid is an aqueous cutting fluid.

2. The application of the nano copper in the cutting fluid according to claim 1, wherein the mass percentage, in the cutting fluid, of the nano copper is 1%-10%; and the nano copper is paste with a particle size of 10-50 nm.

3. The application of the nano copper in the cutting fluid according to claim 2, wherein the nano copper substitutes part or all of the functional additives in the cutting fluid, and the functional additives comprise one or more of a preservative, an anti-rust agent, a sterilizing agent, a compression-resisting agent and a lubricant.

4. The application of the nano copper in the cutting fluid according to claim 3, wherein the cutting fluid is an aqueous aluminum alloy semi-synthetic cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00016 Nano copper   1-10% T22 naphthenic oil   20-30% Potassium oleate   2-10% Triethanolamine   3-8% Oleyl alcohol polyoxyethylene ether   3-8% Methyl diethanolamine   1-6% Boric acid   1-6% Oleic acid   1-5% Coupling agent  0.5-2% Isopropanolamine  0.5-2% Benzotrizaole  0.1-1% Defoamer 0.01-0.1% and the balance of water, based on 100% in total.

5. The application of the nano copper in the cutting fluid according to claim 4, wherein the cutting fluid is an aqueous aluminum alloy semi-synthetic cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00017 Nano copper    3% T22 naphthenic oil   24% Potassium oleate  5.8% Triethanolamine  5.5% Oleyl alcohol polyoxyethylene ether  5.5% Methyl diethanolamine  3.5% Boric acid    3% Oleic acid    2% Coupling agent    1% Isopropanolamine  0.8% Benzotrizaole  0.5% Defoamer  0.05% Water, 45.35%.

6. The application of the nano copper in the cutting fluid according to claim 3, wherein the cutting fluid is an aqueous magnesium alloy semi-synthetic cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00018 Nano copper   1-10% T22 naphthenic oil   25-35% Petroleum sodium sulfonate   8-15% Anionic chelating agent   2-10% Mixed alcohol amine   5-10% Oleyl alcohol polyoxyethylene ether   2-5% Fatty alcohol polyoxylethylene ether   2-5% Tall oil   3-8% Coupling agent   5-10% Sterilizing agent  0.5-2% Benzotrizaole  0.1-1% Defoamer 0.01-0.1% and the balance of water, based on 100% in total.

7. The application of the nano copper in the cutting fluid according to claim 6, wherein the cutting fluid is an aqueous magnesium alloy semi-synthetic cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00019 Nano copper    3% T22 naphthenic oil 31.95% Petroleum sodium sulfonate   11% Anionic chelating agent    6% Mixed alcohol amine  6.5% Oleyl alcohol polyoxyethylene ether    3% Fatty alcohol polyoxylethylene ether    3% Tall oil    4% Coupling agent    8% Sterilizing agent    1% Benzotrizaole  0.5% Defoamer  0.05% Water   22%.

8. The application of the copper in the cutting fluid according to claim 3, wherein the cutting fluid is an emulsion type cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00020 Nano copper   1-10% T22 naphthenic oil   50-70% Petroleum sodium sulfonate   5-10% Oleic acid   4-6% Triethanolamine   1-3% Monoethanolamine   1-3% Fatty alcohol polyoxylethylene ether   1-3% Diethylene glycol monobutyl ether  0.5-2% Boric acid   1-3% Mixed binary acid (C10-C12)  0.1-1% Span 80   2-5% Sterilizing agent  0.5-2% Benzotrizaole  0.1-1% Defoamer 0.01-0.1% and the balance of water, based on 100% in total.

9. The application of the nano copper in the cutting fluid according to claim 8, wherein the cutting fluid is an emulsion type cutting fluid, and comprises the following components in percentage by mass: TABLE-US-00021 Nano copper    3% T22 naphthenic oil 69.95% Petroleum sodium sulfonate    7% Oleic acid    5% Triethanolamine  1.5% Monoethanolamine  1.5% Fatty alcohol polyoxylethylene ether    2% Diethylene glycol monobutyl ether    1% Boric acid  1.5% Mixed binary acid (C10-C12)  0.5% Span 80  2.5% Sterilizing agent    1% Benzotrizaole  0.4% Defoamer  0.05% Water  3.1%.

Description

BRIEF DESCRIPTION OF DRAWING

(1) In order to make the content of the present invention easier to understand, the present invention will be further described in detail below in accordance with the specific embodiments of the present invention and in conjunction with the drawing.

(2) FIG. 1 is a schematic diagram showing a stock solution of a nano copper cutting fluid and a 5% aqueous solution of a nano copper cutting fluid in Embodiment 1 of the present invention.

DETAILED DESCRIPTION

(3) In order to describe the technical content, achieved objectives and effects of the present invention in detail, the following description will be given in conjunction with the embodiments.

(4) The reagents adopted in the specification, unless otherwise specified, are all commercially available products.

(5) According to the application, in the cutting fluid, of the self-dispersible nano copper with the organic long-carbon chain provided in the present invention, the mass percentage, in the cutting fluid, of the nano copper is 1-10%, preferably 2-5%. The nano copper is a metal surface coated with a long-carbon chain organic matter. The long-carbon chain organic matter is dialkyl dithiophosphate (HDDP) and a derivative thereof.

(6) The preparation method of the self-dispersible nano copper with the organic long-carbon chain includes the following steps.

(7) Step 1: mixing a copper source with water to obtain a copper source solution, putting the copper source solution into nitrogen, argon or air atmosphere to heat up to 40° C.-75° C., preferably 50° C.-65° C., more preferably 55° C., where the copper source aqueous solution is selected from one or more of a copper sulfate pentahydrate aqueous solution, a copper chloride aqueous solution, a copper bromide aqueous solution, a copper acetate aqueous solution, a copper nitrate aqueous solution and an copper acetylacetonate aqueous solution.

(8) Step 2: adding a reducing agent into the copper source solution heated in step 1 to obtain a reduced copper source solution, where the reducing agent is selected from one or more of hydrazine hydrate, sodium hypophosphite (NaH.sub.2PO.sub.2), sodium borohydride, ascorbic acid (vitamin C) and sodium ascorbate.

(9) Step 3: mixing a dialkyldithiophosphate coating agent with an organic solvent to obtain a coating agent solution, where the organic solvent is selected from one or more of petroleum ether 60-90, dichloromethane, trichloromethane, pentane, ethyl acetate, diethyl ether, carbon tetrachloride, benzene, methylbenzene, dimethylbenzene and base oil.

(10) Step 4: adding the coating agent solution into the reduced copper source solution to react, thereby obtaining a nano copper mixture.

(11) Before step 1 starts, the HDDP coating agent is firstly prepared: a carbon-based alcohol compound reacts with phosphorus pentasulfide to obtain the dialkyldithiophosphate coating agent. In the embodiment, a molar ratio of the carbon-based alcohol compound to the phosphorus pentasulfide can be selected according to the practical needs, preferably 2:1 to 8:1. The carbon-based alcohol compound may be fatty alcohol and aromatic alcohol, preferably at least one of saturated fatty alcohols, for example, one or more of alcohol, isopropanol, isooctanol, decanol, n-dodecyl alcohol and dodecyl isomeric alcohol.

(12) A molar ratio of the copper source to the dialkyldithiophosphate coating agent may be adjusted according to the specific needs, preferably 1:5 to 5:1. Preferably, the molar ratio of the copper source to the reducing agent is 1:20 to 20:1.

(13) The method may further include: performing fluid separation treatment on the nano copper mixture, and removing a lower-layer water phase to obtain an upper-layer oil phase; centrifuging the oil phase to obtain upper-layer liquor; and concentrating the upper-layer liquor to obtain nano copper paste. The particle size of the nano copper is detected to be 10-50 nm through a nano particle size detector. A mass ratio of pure copper in nano copper preparation is measured to be 20%-25% through a thermal gravimetric analyzer.

(14) The aqueous aluminum alloy semi-synthetic cutting fluid provided in the present invention includes the following components in percentage by mass: 1-10%, preferably 2-5% of nano copper, 20-30%, preferably 22-25% of T22 naphthenic oil, 2-10%, preferably 4-6% of potassium oleate, 3-8%, preferably 4-6% of triethanolamine, 3-8%, preferably 4-6% of oleyl alcohol polyoxyethylene ether, 1-6%, preferably 3-5% of methyl diethanolamine, 1-6%, preferably 3-5% of boric acid, 1-5%, preferably 2-3% of oleic acid, 0.5-1% of a coupling agent, 0.5-2%, preferably 0.5-1% of isopropanolamine, 0.1-1%, preferably 0.4-0.6% of benzotriazole, 0.04-0.06% of a defoamer, and the balance of water, based on 100% in total.

(15) The self-dispersible nano copper with the organic long-carbon chain can be directly applied to the preparation of the aluminum alloy cutting fluid, can be taken as a multi-functional additive to simultaneously substitute the anti-rust agent (alkyl phosphorous acid), the lubricant (polyether) and the sterilizing agent, so that the production cost of the cutting fluid is remarkably reduced.

(16) The cutting fluid provided in the present invention is the aqueous magnesium alloy semi-synthetic cutting fluid, and includes the following components in percentage by mass: 1-10%, preferably 2-5% of nano copper, 25-35%, preferably 30-35% of T22 naphthenic oil, 8-15%, preferably 10-12% of petroleum sodium sulfonate, 2-10%, preferably 5-8% of an anionic chelating agent, 5-10%, preferably 5-8% of mixed alcohol amine, 2-5%, preferably 2-4% of oleyl alcohol polyoxyethylene ether, 2-5%, preferably 2-4% of fatty alcohol polyoxylethylene ether, 3-5% of tall oil, 5-10%, preferably 6-8% of a coupling agent, 0.5-2%, preferably 0.5-1% of a sterilizing agent, 0.4-0.6% of benzotriazole, 0.04-0.06% of a defoamer, and the balance of water, based on 100% in total.

(17) The self-dispersible nano copper with the organic long-carbon chain can be directly applied to the preparation of the magnesium alloy cutting fluid, and completely substitutes the conventional dicarboxylic acid to serve as an anti-corrosion additive. Meanwhile, extra lubricating effect and sterilizing effect are brought to the cutting fluid system after nano copper is introduced, so that the proportion of other additives is further reduced, and the cost of the formula is reduced.

(18) The cutting fluid provided in the present invention is the emulsion type cutting fluid, and includes the following components in percentage by mass: 1-10%, preferably 2-5% of nano copper, 50-70%, preferably 65-70% of T22 naphthenic oil, 5-10%, preferably 7-9% of petroleum sodium sulfonate, 4-6% of oleic acid, 1-3%, preferably 1-2% of triethanolamine, 1-3%, preferably 1-2% of monoethanolamine, 1-3%, preferably 1-2% of fatty alcohol polyoxylethylene ether, 0.5-2%, preferably 0.5-1% of diethylene glycol monobutyl ether, 1-3%, preferably 1-2% of boric acid, 0.1-1% of mixed dicarboxylic acid (C10-C12), 2-5%, preferably 2-3% of Span 80, 0.5-2%, preferably 0.5-1% of a sterilizing agent, 0.1-1%, preferably 0.2-0.5% of benzotriazole, 0.01-0.1%, preferably 0.04-0.06% of a defoamer, and the balance of water, based on 100% in total.

(19) The self-dispersible nano copper with the organic long-carbon chain can be directly applied to the preparation of the aluminum alloy cutting fluid, is taken as a multi-functional additive to simultaneously substitute the anti-rust agent (alkyl phosphorous acid), the lubricant (polyether and Span 80) and the sterilizing agent, so that the production cost of the cutting fluid is remarkably reduced.

(20) The stable dispersion, in the cutting fluid, of the nano copper matter prepared in the present invention benefits from two main factors: firstly, a great deal of coating agent is introduced in the preparation process, and the nano copper is bonded with the coating agent to generate a stable nano copper cluster; a mass main body of the cluster is the coating agent, and therefore, the cluster mainly exhibits the physical property of coating agent molecules instead of the physical property of the exposed nano copper powder; and secondly, the cutting fluid system is generally a mixed system including a great number of surface activator molecules through which the coated nano copper cluster can be well dispersed into micelles of emulsion liquid or directly dissolved into water without forming an independent oil layer or sediments. If only the exposed nano copper powder is simply added, the dispersion effect will be difficult to achieve due to the lack of effective acting force and an acting position on the surface.

Embodiment 1

(21) An aqueous aluminum alloy semi-synthetic cutting fluid in the embodiment included the following components in percentage by mass:

(22) TABLE-US-00007 Nano copper    3% T22 naphthenic oil   24% Potassium oleate  5.8% Triethanolamine  5.5% Oleyl alcohol polyoxyethylene ether  5.5% Methyl diethanolamine  3.5% Boric acid    3% Oleic acid    2% Coupling agent    1% Isopropanolamine  0.8% Benzotrizaole  0.5% Defoamer  0.05% Water 45.35%.

(23) A preparation method of self-dispersible nano copper with an organic long-carbon chain included the following steps.

(24) A HDDP coating agent was firstly prepared: a carbon-based alcohol compound and phosphorus pentasulfide were added into a 250 mL simple-opening flask, the opening of which was covered with a plug and connected to a gas guide tube, a reaction mixture was heated up to 80º C. under a stirring condition and was kept at the temperature for 3 h, and hydrogen sulfide gas released during the reaction was introduced into a copper sulfate aqueous solution through the gas guide tube. Residual solids in the reaction system were removed after the reaction to obtain transparent light-yellow liquid, namely the dialkyldithiophosphate coating agent. In the embodiment, hydrogen sulfide gas generated during the reaction also could be sucked through alkaline systems such as a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, a calcium hydroxide aqueous solution or emulsion. The hydrogen sulfide gas also could be transformed into sulfur dioxide through a combustion or oxidation method for being sucked.

(25) Step 1: a copper source and water were added into a 500 mL beaker, so that the copper source was sufficiently dissolved into water to obtain a copper source solution; the copper source solution was poured into a reaction kettle which was then closed; and nitrogen gas was introduced into the reaction kettle to heat up a reaction system to 55° C.

(26) Step 2: a reducing agent was added into the reaction kettle and reaction was performed for 10 min under the stirring condition.

(27) Step 3: a dialkyldithiophosphate coating agent and an organic solvent were mixed in final concentration of 0.1 mol/L to 0.9 mol/L to obtain a coating agent solution.

(28) Step 4: the coating agent solution was added into the reaction kettle, and stirring and heating were stopped after reaction was performed for 2 h.

(29) Step 5: a nano copper mixture was obtained.

(30) The method further included a step 6: the nano copper mixture was poured out from the reaction kettle, liquid separation was performed on the mixture through a liquid separation funnel, and a lower-layer water phase was removed to obtain an upper-layer oil phase; the obtained oil phase was centrifuged to remove relatively great copper powder particles, so that upper-layer liquor was obtained; and the upper-layer liquor was evaporated rotationally, and the solvent was removed to obtain nano copper paste. The upper-layer liquor was purified through reduced-pressure distillation or normal-pressure distillation.

(31) The prepared nano copper was directly applied to the preparation of the aluminum alloy cutting fluid, could be taken as a multi-functional additive to simultaneously substitute the anti-rust agent (alkyl phosphorous acid), the lubricant (polyether) and the sterilizing agent, so that the production cost of the cutting fluid was remarkably reduced. As shown in FIG. 1, the stock solution of the nano copper cutting fluid was at the left side, and a 5% aqueous solution of the nano copper cutting fluid was at the right side, both of which were in a micro-emulsion semi-transparent state.

(32) The embodiment further provided a reference sample 1 in which nano copper was not added as a comparison, where the formula was as shown in table 1.

(33) TABLE-US-00008 TABLE 1 Formula of reference example Cutting Fluid (without nano copper) in reference example 1 Additive Content (mass ratio %) Boric acid 3 Mixed binary acid (C10-C12) 2 Potassium oleate 5.8 Benzotrizaole 0.5 Isopropanolamine 0.8 Triethanolamine 5.5 Methyl diethanolamine 3.5 Water 36.35 Chlorinated paraffin (C14-C17) 4 Oleyl alcohol polyoxyethylene ether 5.5 Oleic acid 2 Coupling agent 2 Sterilizing agent 2 T22 naphthenic oil 24 Nano copper 0 Defoamer 0.05 In total 100

(34) An anti-rust test was performed on the nano copper cutting fluid in Embodiment 1 and the nano copper-free cutting fluid in reference example as shown in the following Table 2.

(35) TABLE-US-00009 TABLE 2 Comparison between the nano copper cutting fluid in Embodiment 1 and the nano copper-free cutting fluid in reference example. Cutting Fluid Cutting Fluid (containing (without nano nano copper) copper) in in reference Test Test Items Embodiment 1 example 1 Standards pH (25° C.) 9.5 9.2 GB/T 6144 Anti-rust experiment, Grade A Grade A GB/T 6144 first-grade grey cast iron, 24 hours Anti-rust experiment, Grade A Grade B GB/T 6144 LY12 hard aluminum, 8 hours Anti-rust experiment, No rust spot, One to two GB/T 6144 cast-iron scrap grade e rust spots method, 2 hours Sedimentation No — experiment sedimentation for six mouths

(36) The results showed that, for the cutting fluid in Embodiment 1, the added nano copper substituted alkyl phosphorous acid with a high price in case of not reducing the anti-rust effect of an aluminum alloy. Meanwhile, the cutting fluid did not need polyether and other sterilizing agents due to its remarkable lubricating and sterilizing properties, so that the formula system of the cutting fluid was greatly simplified, and the production steps were simplified while the cost was reduced. Sedimentation experiment was further performed on the cutting fluid in the embodiment, and the test results showed that there were no sediments 6 months later, and therefore, the nano copper in the embodiment was stably and uniformly dispersed in the aqueous aluminum alloy semi-synthetic cutting fluid for a long time.

(37) The nano copper in the application of the embodiment exhibited efficient anti-corrosion property on the aluminum alloy due to the following reasons.

(38) A coating agent of the nano copper was formed by phosphorodithioate with a long organic carbon chain, and phosphorodithioate exhibited very efficient bonding ability for an aluminum alloy surface, so that the aluminum alloy surface was coated with coating agent molecules to isolate from water.

(39) The nano copper cluster in nano copper paste could be effectively deposited on the aluminum alloy surface in the processing process, so that a second isolating layer was generated by the alloy surface and water, and thus, the anti-corrosion property was further strengthened.

(40) The nano copper improved the lubricating property of the aluminum alloy cutting fluid due to the fact that:

(41) Phosphorodithioate exhibited very efficient bonding capacity with the aluminum alloy surface and formed an extreme pressure resistant oil film, so that the aluminum alloy surface is lubricated. Phosphorodithioate and a steel tool generated chemical reaction in a processing process to generate an iron sulfide film, so that the tool surface exhibited equivalent extreme pressure resistant property and lubricating property. Antibacterial ability of the nano copper was due to stabilizing ability of the nano copper cluster. Although the surface of the nano copper cluster was coated with phosphorodithioate, yet the effect was reversible. A few coating agent molecules were free in a processing process, so that the surface of the nano copper cluster was exposed to exhibit the antibacterial ability.

Embodiment 2

(42) An aqueous magnesium alloy semi-synthetic cutting fluid in the embodiment included the following components in percentage by mass:

(43) TABLE-US-00010 Nano copper    3% T22 naphthenic oil 31.95% Petroleum sodium sulfonate   11% Anionic chelating agent    6% Mixed alcohol amine  6.5% Oleyl alcohol polyoxyethylene ether    3% Fatty alcohol polyoxylethylene ether    3% Tall oil    4% Coupling agent    8% Sterilizing agent    1% Benzotrizaole  0.5% Defoamer  0.05% Water   22%.

(44) A preparation method of self-dispersible nano copper with an organic long-carbon chain in the embodiment was the same with that in Embodiment 1, and the difference was that:

(45) In step 1, the carbon-based alcohol compound is a mixture consisting of 65% (in molar percentage) of n-dodecyl alcohol, 20% of isooctanol and 15% of alcohol, where the total mass was 53.9 g (350 mmol), dosage of phosphorus pentasulfide was 22.2 g (100 mmol), and a molar ratio of mixed alcohol to phosphorus pentasulfide was 3.5:1, and a dialkyldithiophosphate mixture was finally obtained in step 1.

(46) In step 2, the copper source was copper sulfate pentahydrate with dosage of 37.4 g (150 mmol), 200 mL water was used for dissolving copper sulfate pentahydrate, a reducing agent was 80% hydrazine hydrate with dosage of 120 mL (about 2 mol), dosage of the dialkyldithiophosphate mixture was 48 g (120 mmol), a molar ratio of copper sulfate pentahydrate to the reducing agent was 3:40, a molar ratio of copper sulfate pentahydrate to dialkyldithiophosphate was 5:4 and the organic solvent was petroleum ether 60-90 with dosage of 250 mL.

(47) The prepared self-dispersible nano copper was directly applied to the preparation of the magnesium alloy cutting fluid, and completely substituted the conventional dicarboxylic acid to serve as an anti-corrosion additive. Meanwhile, extra lubricating effect and sterilizing effect were brought to the cutting fluid system after nano copper was introduced, so that the proportion of other additives was further reduced, and the cost of the formula was reduced. The embodiment further provided a reference sample 2 in which nano copper was not added as a comparison, where the formula was as shown in table 3.

(48) TABLE-US-00011 TABLE 3 Formula of reference example Additive Content (mass ratio %) Anionic chelating agent 6 Benzotrizaole 0.5 Mixed alcohol amine 6.5 Water 22 Petroleum sodium sulfonate 11 Oleyl alcohol polyoxyethylene ether 3.5 Fatty alcohol polyoxylethylene ether 3.5 Coupling agent 8 Sterilizing agent 2 Tall oil 4 T22 naphthenic oil 32.95 Nano copper 0 Defoamer 0.05 In total 100

(49) An anti-rust test was performed on the cutting fluid in Embodiment 2 and the nano copper-free cutting fluid in reference example as shown in the following Table 4.

(50) TABLE-US-00012 TABLE 4 Comparison between the cutting fluid in Embodiment 2 and the nano copper-free cutting fluid in reference example Cutting Cutting Fluid Fluid (containing (without nano nano copper) in copper) in Embodiment reference Test Test Items 2 example Standards pH (25° C.) 9.5 9.2 GB/T 6144 Anti-rust experiment, Grade A Grade A GB/T 6144 first-grade grey cast iron, 24 hours Anti-rust experiment, no rust spot, One to GB/T 6144 cast-iron scrap grade e two method, 4 hours rust spots Magnesium alloy No color Not Magnesium blocks normal-temperature change changed were grounded and soaking experiment, color soaked in an aqueous 5 days solution of a 5% stock solution of the cutting fluid at the room temperature, and a color changing phenomenon of the magnesium blocks was observed at the room temperature Magnesium alloy No color Slightly Magnesium blocks high-temperature change blackened were grounded and soaking experiment, soaked in an aqueous 12 hours solution of a 5% stock solution of the cutting fluid at the room temperature, and a color changing phenomenon of the magnesium blocks was observed at 60° C. Sedimentation No — experiment sedimentation for six mouths

(51) The results showed that, for the cutting fluid in Embodiment 2, the adding proportion of the nano copper in the magnesium alloy cutting fluid could be reduced to about 1% of cost advantage, which formed striking comparison with the adding proportion of 15% dicarboxylic acid, sufficiently exhibited high efficiency, on the anti-corrosion effect of the magnesium alloy, of the nano copper and low cost of the prepared cutting fluid. Sedimentation experiment was further performed on the cutting fluid in the embodiment, and the test results showed that there were no sediments 6 months later, and therefore, the nano copper t was stably and uniformly dispersed in the aqueous aluminum alloy semi-synthetic cutting fluid in the embodiment for a long time.

(52) The nano copper in the application of the embodiment exhibited efficient anti-corrosion property on the magnesium alloy due to the following reasons.

(53) The coating agent of nano copper was formed by phosphorodithioate with a long organic carbon chain. The phosphorodithioate exhibited very efficient bonding ability with a magnesium alloy surface, so that the magnesium alloy surface was coated with coating agent molecules to isolate from water.

(54) The nano copper cluster in nano copper paste could be effectively deposited on the magnesium alloy surface in the processing process, so that a second isolating layer was generated by the alloy surface and water to further strength the anti-corrosion property.

(55) In the processing process, magnesium metal reacted with thiophosphoric acid to generate a little magnesium thiophosphate which was deposited on a metal surface to form a third isolating layer. The nano copper with a long-carbon chain exhibited high anti-corrosion property on the magnesium alloy, and quantity demanded on the nano copper was greatly reduced, so that the integral cost of the cutting fluid was remarkably reduced. In addition, the proportion of other related additives, which was also one of causes to the reduction of the proportion cost, was reduced due to the lubricating effect and the sterilizing effect of nano copper.

Embodiment 3

(56) An emulsion type cutting fluid in the embodiment included the following components in percentage by mass:

(57) TABLE-US-00013 Nano copper    3% T22 naphthenic oil 69.95% Petroleum sodium sulfonate    7% Oleic acid    5% Triethanolamine  1.5% Monoethanolamine  1.5% Fatty alcohol polyoxylethylene ether    2% Diethylene glycol monobutyl ether    1% Boric acid  1.5% Mixed binary acid (C10-C12)  0.5% Span 80  2.5% Sterilizing agent    1% Benzotrizaole  0.4% Defoamer  0.05% Water  3.1%.

(58) A preparation method of self-dispersible nano copper with an organic long-carbon chain in the embodiment was the same with that in Embodiment 1, and the difference was that:

(59) On step 1, the carbon-based alcohol compound was isooctanol with dosage of 45.5 g (350 mmol), dosage of phosphorus pentasulfide was 22.2 g (100 mmol), a molar ratio of isooctanol to phosphorus pentasulfide was 3.5:1, and di(2-ethylhexyl)phosphorodithioic acid was finally obtained in step 1.

(60) In step 2, the copper source was copper sulfate pentahydrate with dosage of 37.4 g (150 mmol), 200 mL water was used for dissolving copper sulfate pentahydrate, a reducing agent was 80% hydrazine hydrate with dosage of 120 mL (about 2 mol), dosage of the di(2-ethylhexyl)phosphorodithioic acid was 42.5 g (120 mmol), a molar ratio of copper sulfate pentahydrate to the reducing agent was 3:40, a molar ratio of copper sulfate pentahydrate to di(2-ethylhexyl)phosphorodithioic acid was 5:4 and the organic solvent was petroleum ether 60-90 with dosage of 250 mL.

(61) The prepared nano copper was directly applied to the preparation of the emulsion type cutting fluid, and could be taken as a multi-functional additive to simultaneously substitute the anti-rust agent (petroleum sodium sulfonate), the lubricant (polyether and Span 80) as well as the sterilizing agent, so that the production cost of the cutting fluid was remarkably reduced. The embodiment further provided a reference sample 3 in which nano copper was not added as a comparison, where the formula was as shown in table 5.

(62) TABLE-US-00014 TABLE 5 Formula of referenc example Content (mass ratio %, Additive formula without nano copper) Mixed binary acid (C10-C12) 0.5 Boric acid 1.5 Benzotrizaole 0.4 Monoethanolamine 1.5 Triethanolamine 1.5 Diethylene glycol monobutyl ether 1 Oleic acid 5 Water 3.1 Petroleum sodium sulfonate 9 Fatty alcohol polyoxylethylene ether 2 Span 80 5 Sterilizing agent 2 T22 naphthenic oil 67.45 Nano copper 0 Defoamer 0.05 In total 100

(63) An anti-rust test was performed on the nano copper cutting fluid in Embodiment 3 and the nano copper-free cutting fluid in reference example as shown in the following Table 6.

(64) TABLE-US-00015 TABLE 6 Comparison between the nano copper cutting fluid in Embodiment 3 and the nano copper-free cutting fluid in reference example. Cutting Fluid Cutting Fluid (containing (without nano copper) in nano copper) Test Test Items Embodiment 3 in reference Standards pH (25° C.) 9.0 9.2 GB/T 6144 Anti-rust Grade A Grade A GB/T 6144 experiment, first-grade grey cast iron, 24 hours Anti-rust No rust spot, No rust spot, GB/T 6144 experiment, grade e grade e cast-iron scrap method, 2 hours Sedimentation No — experiment sedimentation for six mouths

(65) The results showed that, for the cutting fluid in Embodiment 3, the nano copper was added to substitute a conventional lubricant and a conventional compression-resisting agent in case of not reducing main performance indexes of the emulsion type cutting fluid, so that the formula system of the cutting fluid was greatly simplified, and the production steps were also simplified while the cost was reduced. Sedimentation experiment was further performed on the cutting fluid in the embodiment, and the test results showed that there were no sediments 6 months later, and therefore, the nano copper was stably and uniformly dispersed in the aqueous aluminum alloy semi-synthetic cutting fluid in the embodiment for a long time. Other performance advantages were the same with those in Embodiment 1 and Embodiment 2, which were not repeated here.

(66) It is apparent that the above-described embodiments are merely illustrative of the examples, and are not intended to limit the embodiments. Other variations or modifications of various forms may be made by a person skilled in the art in light of the above description. There is no need and no way to exhaustively describe all of embodiments. Obvious changes or variations resulting therefrom are still within the scope of the present invention.