Cobalt phosphate octahydrate nanoflower and titanium alloy cold rolling lubricant

Abstract

The application discloses a kind of eight hydrated cobalt phosphate nanoflower and titanium alloy cold rolling lubricant, first, divalent soluble cobalt salt solution is added dropwise in the phosphate buffer solution being stirred, stir until it changes from purple solution to a large number of pink precipitate, separate pink precipitate and obtain cobalt phosphate nanoflower.The eight hydrated cobalt phosphate nanoflower is composed of thick slices with different growth directions, and each thick slice is stacked by 4nm or so multilayer slices.Then the eight hydrated cobalt phosphate nanoflower is dispersed in the cold rolling lubricating base liquid to obtain a titanium alloy cold rolling lubricant, which is used in the cold rolling process of titanium alloy, has good lubricating effect and boundary lubrication performance, can also significantly improve the wear resistance, effectively reduces the occurrence of scratch, pull flower, scratch, sintering, welding, pull explosion and other phenomena.

Description

Technical Field

[0001] This invention belongs to the field of cold rolling lubricants, and relates to a cold rolling lubricant additive, particularly to a cobalt phosphate nanoflower octahydrate and a titanium alloy cold rolling lubricant. Background Technology

[0002] Titanium alloys, with their excellent corrosion resistance, specific strength, non-magnetic properties, and high and low temperature performance, have become remarkable high-performance new materials. Since the 1950s, they have been vibrant in both military and civilian fields, with the titanium industry growing at an average annual rate of about 8%. In the aerospace field, titanium and its alloys are mainly used in aerospace and military industries, with aerospace applications accounting for about 80% of total titanium production. In civilian applications, titanium is used in golf club heads, bicycles, and various containers (pressure vessels, chemical and electroplating baths). In the medical field, medical titanium alloys are non-toxic, lightweight, and have high specific strength. They also possess excellent biocompatibility and corrosion resistance, making them ideal medical metal materials suitable for implantation. Furthermore, the construction, agriculture and animal husbandry, nuclear industry, ordnance, and automotive industries have all experienced strong growth.

[0003] While titanium alloys possess inherent advantages in many fields due to their material properties, and their high finished product price and large profit margins, their complex processing, high difficulty, and persistently high scrap rate are major headaches for many titanium alloy processing companies. Therefore, selecting reliable titanium alloy cold rolling lubricants, also known as drawing oils or forming oils, is particularly important. Among these, the lubricating properties of the cold rolling lubricant are a crucial performance characteristic during the cold rolling process.

[0004] Patent CN103409202A discloses a cold-rolling lubricant for titanium and titanium alloy foils, using No. 7 industrial white oil as the base oil and incorporating various composite additives, including anti-wear agents, oiliness agents, antioxidants, corrosion inhibitors, antioxidants, antifoaming agents, and metal deactivators. This invention's cold-rolling lubricant for titanium and titanium alloy foils exhibits good lubrication properties in process tunnels, increases oil film strength in the deformation zone, reduces the coefficient of friction, has stable composition and performance, and is non-corrosive, non-toxic, and odorless to metals and equipment. However, the anti-wear agent used is composed of borate and ammonium thiophosphate, which is an oil-soluble liquid anti-wear agent with a limited molecular weight, resulting in limited oil film thickness and load-bearing capacity. In contrast, nanomaterials, currently a hot research topic, are solid substances that do not dissolve in base oil to form small molecules, possess better microscopic mechanical properties, form thicker oil films, and have stronger load-bearing capacity. Furthermore, oil-soluble anti-wear agents are dissolved in the base oil; when treating waste oil, phosphorus-containing waste oil requires chemical precipitation for complete removal. Nanomaterials containing phosphorus are easy to process because they are solids and can be directly filtered out. Nanomaterials have advantages in waste oil treatment and environmental protection. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by proposing a cold-rolling lubricant for titanium alloys. Cobalt phosphate octahydrate nanoflowers are added to the cold-rolling lubricant base fluid, with the cobalt phosphate octahydrate nanoflowers comprising 0.5-80% by mass. These cobalt phosphate octahydrate nanoflowers are spherical structures composed of thick sheets with different growth directions, each sheet consisting of multiple layers of approximately 4 nm thick sheets stacked together. Adding cobalt phosphate octahydrate nanoflowers to the cold-rolling lubricant base fluid for use in the cold-rolling process of titanium alloys provides excellent lubrication and boundary lubrication performance, significantly improves wear resistance, and effectively reduces the occurrence of scratches, scoring, sintering, welding, and bursting.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A cold rolling lubricant for titanium alloys includes a cold rolling lubricant base fluid and cobalt phosphate nanoflowers octahydrate dispersed in the cold rolling lubricant base fluid, wherein the mass percentage of cobalt phosphate nanoflowers octahydrate is 0.5-80%.

[0008] Preferably, the cold-rolling lubricating base fluid is an oil-based lubricating oil selected from any one or a mixture of multiple alkanes, alkenes, alkynes, halogenated hydrocarbons, hydrogenated hydrocarbons, aromatic hydrocarbons, and heterocyclic compounds.

[0009] Specifically, it can be 500SN base oil, PAO8 base oil, or peanut oil base oil.

[0010] Preferably, the microstructure of the cobalt phosphate nanoflower octahydrate is: a spherical structure composed of thick sheets with different growth directions, each thick sheet being composed of multiple nanoscale thin sheets stacked together.

[0011] Preferably, the thickness of the sheet is 3-10 nanometers.

[0012] Preferably, the diameter of the spherical structure of the cobalt phosphate nanoflower octahydrate is 3-15 micrometers.

[0013] This invention also provides a method for preparing cobalt phosphate nanoflowers octahydrate, as detailed below:

[0014] A divalent soluble cobalt salt solution was added dropwise to a phosphate buffer solution that was being stirred until the solution changed from purple to a large amount of pink precipitate. The pink precipitate was then separated to obtain cobalt phosphate nanoflowers.

[0015] Preferably, the pH of the phosphate buffer solution is 8-12.

[0016] Preferably, the molar ratio of the divalent soluble cobalt salt solution to the phosphate buffer solution is 1:0.7-1.5.

[0017] Preferably, the stirring speed of the phosphate buffer solution is greater than 200 rpm.

[0018] Preferably, the divalent soluble cobalt salt solution includes any one or a mixture of several of cobalt acetate, cobalt nitrate, cobalt sulfate, and cobalt chloride.

[0019] This application uses a different preparation method and application principle than the porous copper phosphate in the applicant's prior patent "A method for improving the lubrication performance of lubricating oil" (patent number: ZL202210587306.6).

[0020] The preparation methods differ: the copper phosphate preparation method in the patented application is a one-step precipitation method, utilizing the precipitation and crystallization of phosphate and copper ions. The applicant discovered in experiments that while the one-step precipitation method can yield cobalt phosphate nanoflowers, it cannot yield cobalt phosphate octahydrate nanoflowers. The SEM image of the cobalt phosphate octahydrate nanoflowers in this application is shown below. Figure 1 As shown, the nanoflower is spherical in shape and composed of thick plates with different growth directions. Each thick plate is made up of multiple layers of thin plates about 4 nm thick, as shown in the figure. Figure 2 As shown. XRD pattern as follows. Figure 3 As shown, the thickness of the nanosheets was measured as follows: Figure 4 As shown. The microstructure of cobalt phosphate octahydrate obtained by a simple precipitation method is as follows. Figure 5 As shown, these are large, irregularly shaped, and aggregated small particles. This application demonstrates that cobalt phosphate octahydrate nanoflowers can only be formed under stirring and with sufficient contact between the solution and the particles.

[0021] The lubrication mechanisms are different: there are two main mechanisms in this application:

[0022] (1) Adsorption to form a protective layer—anti-wear. Due to its reactive chemical properties, titanium alloys readily adsorb elements such as nitrogen and oxygen. When cobalt phosphate octahydrate nanoflowers come into contact with titanium alloys, they adsorb onto the alloy surface via PO-Ti bonds, forming a protective layer. This effectively protects the titanium alloy from severe wear and adhesion during cold rolling, achieving excellent lubrication performance. When lubricating oil or fluid is used alone, a large amount of wear debris adheres to the surface of the titanium alloy, resulting in high roughness. Figure 6 As shown in the figure. When lubricating with a lubricating oil containing cobalt phosphate nanoflowers octahydrate, a layer of material was observed deposited on the surface, and the surface became smoother. The SEM image and EDS analysis of the deposited layer on the titanium alloy surface are shown in the figure. Figure 7 As shown. The formed PO-Ti bonds have been confirmed by XPS testing, as... Figure 8 As shown.

[0023] (2) Low Shear Force-Lubrication at the Nanosheet Interface in the Special Nanoflower Structure. This cobalt phosphate octahydrate nanoflower is composed of thick sheets with different growth directions, each sheet consisting of multiple layers of approximately 4 nm thick sheets stacked together. Numerous studies have shown that the interfacial shear force between two-dimensional nanosheet layers is extremely low. In this application, after the thick nanosheets are adsorbed onto the titanium alloy surface, under the action of mechanical friction, inter-sheet slippage occurs between the thin nanosheets within the thick nanosheets. This slippage resistance is very low, thereby promoting lubrication. To demonstrate the low shear force slippage between the sheets, Stribek curves were measured, such as... Figure 9 As shown, when the lubricant containing cobalt phosphate nanoflowers octahydrate is added, the tribological coefficient of the curve decreases in the boundary lubrication, mixed lubrication, and fluid lubrication regions, and the curve shifts downward as a whole. Due to the presence of the adsorption protective layer, the oil film thickness increases, and the curve shifts to the right.

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] (1) The preparation method is simple and easy to implement, the experimental process is mild and simple, no special equipment is required, and no harsh experimental methods such as high temperature are needed, which is in line with the green and environmentally friendly approach.

[0026] (2) The raw materials are widely available and economical, and can be widely used.

[0027] (3) Excellent lubrication effect and boundary lubrication performance, improve machining accuracy, protect mold, extend mold life, and effectively reduce the occurrence of scratches, scratches, sintering, welding, bursting and other phenomena. Attached Figure Description

[0028] Figure 1 A scanning electron microscope image of the cobalt phosphate nanoflowers octahydrate in Example 1 is shown.

[0029] Figure 2 A high-magnification scanning electron microscope image of the thick sheet of cobalt phosphate nanoflower octahydrate in Example 1 is shown.

[0030] Figure 3 The XRD and standard XRD patterns of the cobalt phosphate nanoflowers octahydrate in Example 1 are shown.

[0031] Figure 4 The AFM of nanosheets in cadmium-based phosphate nanoflowers after ultrasonic grinding in Example 1 is shown to determine the thickness of the nanosheets.

[0032] Figure 5 SEM images of cobalt phosphate produced by a simple precipitation method are shown.

[0033] Figure 6 The image shows a SEM image of the titanium alloy surface after friction of the blank sample PAO8 in Example 1. A large amount of adhering material is present on the surface, which EDS analysis identifies as titanium alloy wear debris.

[0034] Figure 7 The image shows a SEM image of the titanium alloy surface after friction with 15 wt% cobalt phosphate nanomaterial added to PAO8 in Example 1. A layer of material can be clearly observed deposited on the surface, and the surface is much smoother.

[0035] Figure 8 XPS spectra of the titanium alloy surface containing a phosphate protective layer after the friction test in Example 1 are shown.

[0036] Figure 9 The Stribeck curves are shown for pure PAO8 and PAO8 with 14 wt% nanomaterials added.

[0037] Figure 10 The friction coefficient curve of the lubricant in Example 1 is shown.

[0038] Figure 11 A 3D white light abrasion pattern of the lubricant after friction is shown in Example 1.

[0039] Figure 12 A schematic diagram of the mechanism of this application is shown.

[0040] Figure 13 The friction coefficient curve of the lubricant in Example 2 is shown.

[0041] Figure 14 A comparison of SEM and EDS is shown in Example 2.

[0042] Figure 15 The friction coefficient curve of the lubricant in Example 3 is shown.

[0043] Figure 16 A comparison of SEM and EDS is shown in Example 3. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0045] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0046] Example 1

[0047] A titanium alloy cold rolling lubricant, comprising cobalt phosphate nanoflowers octahydrate added to PAO8 base oil as the base fluid for cold rolling, wherein the composition by mass percentage is: 0.3g of cobalt phosphate nanoflowers octahydrate and 1.7g of PAO8 base oil.

[0048] (1) Preparation of cobalt phosphate nanoflowers octahydrate

[0049] Preparation of solution A: 100 mL of 0.05 mol / L disodium hydrogen phosphate solution;

[0050] Preparation of solution B: 30 mL of 0.1 mol / L cobalt acetate solution;

[0051] Solution A was stirred on a magnetic stirrer at 500 rpm. Solution B was added dropwise to solution A, and stirring continued until a large amount of pink precipitate formed from the purple solution. The precipitate was filtered, washed with water, and dried in an oven to obtain cobalt phosphate octahydrate nanoflowers. The cobalt phosphate octahydrate nanoflowers were characterized as follows: Figures 1 to 3 As shown, from Figure 1 and Figure 2 The SEM images show that the cobalt phosphate octahydrate nanoflowers in this embodiment are flower spheres with a diameter of approximately 5 micrometers. The nanoflowers are composed of thick plates with different growth directions. Figure 2 It can be seen that each thick slice is composed of multiple thin slices of about 4nm stacked together; Figure 3 The XRD and standard XRD patterns of cobalt phosphate nanoflowers are shown. The comparison in the figures confirms that the product obtained in this embodiment is indeed cobalt phosphate octahydrate.

[0052] (2) To prepare a titanium alloy cold rolling lubricant, weigh 0.3g of cobalt phosphate nanoflowers octahydrate and disperse (stir and disperse) in 1.7g of PAO8 base oil to obtain a titanium alloy cold rolling lubricant.

[0053] (3) Friction Reduction and Wear Resistance Test Method

[0054] A ball-and-disc reciprocating friction test (point-to-surface contact) was conducted on an Rtec friction and wear testing machine: 0.2 mL of the prepared titanium alloy cold-rolled lubricant and the blank sample PAO8 (without any additives) were respectively added to the contact area of ​​the ball and disk. A 6.3 mm diameter GCr15 steel ball was subjected to reciprocating friction with a 4*4 cm TA5 titanium alloy disk.

[0055] Test conditions: Load 10N, speed 128mm / s. Note: This experiment is a point-to-surface contact test. Theoretically, the contact pressure experienced by point-to-surface contact is greater than that of line-to-surface contact during cold rolling, thus better demonstrating the lubricating performance of the lubricant.

[0056] (4) Result Comparison and Analysis

[0057] Compared to the blank sample PAO8 (without any additives), the coefficient of friction was reduced by 69%, and the wear rate was reduced by over 99%. The coefficient of friction curve is shown below. Figure 10 As shown in the image. 3D white light abrasion mark comparison image. Figure 11 As shown.

[0058] Example 2

[0059] A titanium alloy cold rolling lubricant, comprising adding cobalt phosphate nanoflowers octahydrate to 500SN base oil as the base fluid for cold rolling, wherein the composition by mass percentage is: 0.4g of cobalt phosphate nanoflowers octahydrate and 1.6g of 500SN base oil.

[0060] (1) Preparation of cobalt phosphate nanoflowers octahydrate

[0061] Preparation of solution A: 100 mL of 0.05 mol / L disodium hydrogen phosphate solution

[0062] Preparation of solution B: 50 mL of 0.1 mol / L cobalt acetate solution

[0063] Solution A was placed on a magnetic stirrer and stirred at 600 rpm. Solution B was added dropwise to solution A, and stirring continued until a large amount of pink precipitate was produced from the purple solution. The precipitate was filtered, washed with water, and dried in an oven to obtain cobalt phosphate octahydrate nanoflowers.

[0064] (2) To prepare a titanium alloy cold rolling lubricant, weigh 0.4g of cobalt phosphate nanoflowers octahydrate and disperse them in 1.6g of 500SN base oil to obtain a titanium alloy cold rolling lubricant.

[0065] (3) Friction Reduction and Wear Resistance Test Method

[0066] A ball-and-disc reciprocating friction test (point-to-surface contact) was conducted on an Rtec friction and wear testing machine: 0.5 mL of the prepared titanium alloy cold-rolled lubricant and the blank sample 500SN base oil were each added to the contact area of ​​the ball and disk. A 6.3 mm diameter GCr15 steel ball was subjected to reciprocating friction with a 4*4 cm TA5 titanium alloy disk.

[0067] Test conditions: load 20N, speed 128mm / s.

[0068] (4) Result Comparison and Analysis

[0069] Friction coefficient curve as shown Figure 13 As shown, the addition of cobalt phosphate nanoflowers octahydrate reduced the friction coefficient of 500SN base oil from approximately 0.35 to approximately 0.11, and the friction coefficient tended to stabilize significantly over time. SEM and EDS comparison images are shown below. Figure 14As shown, after pure 500SN lubrication, the titanium alloy surface exhibits a large amount of titanium alloy wear debris, exhibiting typical adhesive wear. However, after lubrication with 500SN containing nanomaterials, a layer of cobalt phosphate appears on the surface, and no titanium alloy wear debris adheres. This indicates that this layer of cobalt phosphate significantly reduces adhesive wear of the titanium alloy.

[0070] Example 3

[0071] A titanium alloy cold rolling lubricant, comprising adding cobalt phosphate nanoflowers octahydrate to peanut oil base oil as the base fluid for cold rolling, wherein the composition by mass percentage is: 0.3g of cobalt phosphate nanoflowers octahydrate and 1.7g of peanut oil base oil.

[0072] (1) Preparation of cobalt phosphate nanoflowers octahydrate

[0073] Preparation of Solution A: 200 mL of 0.1 mol / L disodium hydrogen phosphate solution

[0074] Preparation of Solution B: 100 mL of 0.2 mol / L cobalt acetate solution

[0075] Solution A was placed on a magnetic stirrer and stirred at 400 rpm. Solution B was added dropwise to solution A, and stirring continued until a large amount of pink precipitate was produced from the purple solution. The precipitate was filtered, washed with water, and dried in an oven to obtain cobalt phosphate nanoflowers octahydrate.

[0076] (2) To prepare a titanium alloy cold rolling lubricant, weigh 0.3g of cobalt phosphate nanoflowers octahydrate and disperse them in 1.7g of peanut oil base oil to obtain a titanium alloy cold rolling lubricant.

[0077] (3) Friction Reduction and Wear Resistance Test Method

[0078] A ball-disc reciprocating friction test (point-to-surface contact) was conducted on an Rtec friction and wear testing machine: 0.2 mL of the prepared titanium alloy cold-rolled lubricant and the blank control sample peanut oil base oil were respectively added to the contact area of ​​the ball and disk. A 6.3 mm diameter GCr15 steel ball was subjected to reciprocating friction with a 4*4 cm TA5 titanium alloy disk.

[0079] Test conditions: load 10N, speed 112mm / s.

[0080] (4) Result Comparison and Analysis

[0081] Friction coefficient curve as shown Figure 15 As shown, the addition of cobalt phosphate nanoflowers octahydrate reduced the friction coefficient of peanut oil base oil from approximately 0.3 to approximately 0.1, and the friction coefficient tended to stabilize over time. The SEM and EDS comparison images are shown below. Figure 16As shown, when pure peanut oil is used to lubricate titanium alloys, although a large amount of titanium alloy wear debris does not adhere to the surface, numerous grooves appear. This is because peanut oil contains oxygen, which, during sliding, comes into contact with the titanium alloy wear debris, causing the titanium alloy to oxidize and harden. The hardened titanium alloy particles then cut the titanium alloy surface during friction, forming numerous grooves and pits, exhibiting typical fatigue wear. However, when peanut oil containing nanomaterial additives is used for lubrication, the wear surface becomes smooth, with few grooves, and a cobalt phosphate layer appears on the surface. Combining the results of the friction coefficient and wear volume, it can be concluded that this cobalt phosphate layer can protect the titanium alloy surface from severe wear and also has a friction-reducing effect.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cold-rolled lubricant for titanium alloys, characterized in that: It includes a cold rolling lubricant base fluid and cobalt phosphate nanoflowers octahydrate dispersed in the cold rolling lubricant base fluid, wherein the mass percentage of cobalt phosphate nanoflowers octahydrate is 0.5-80%; The preparation method of the cobalt phosphate nanoflowers octahydrate is as follows: A divalent soluble cobalt salt solution was added dropwise to a phosphate buffer solution that was being stirred until the solution changed from purple to a large amount of pink precipitate. The pink precipitate was then separated to obtain cobalt phosphate nanoflowers. The pH of the phosphate buffer solution is 8-12; The stirring speed of the phosphate buffer solution is greater than 200 rpm; The molar ratio of the divalent soluble cobalt salt solution to the phosphate buffer solution is 1:0.7-1.

5.

2. The titanium alloy cold-rolling lubricant according to claim 1, characterized in that: The cold-rolling lubricating base fluid is an oil-based lubricating oil selected from any one or a mixture of multiple alkanes, alkenes, alkynes, halogenated hydrocarbons, hydrogenated hydrocarbons, aromatic hydrocarbons, and heterocyclic compounds.

3. The titanium alloy cold-rolling lubricant according to claim 1, characterized in that: The microstructure of the cobalt phosphate nanoflower octahydrate is: a spherical structure composed of thick sheets with different growth directions, each thick sheet being composed of multiple nanoscale thin sheets stacked together.

4. The titanium alloy cold-rolling lubricant according to claim 3, characterized in that: The thickness of the sheet is 3-10 nanometers.

5. The titanium alloy cold-rolling lubricant according to claim 3, characterized in that: The diameter of the spherical structure is 3-15 micrometers.

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