A SiO2@phosphate glass lubricant for titanium alloy profile extrusion and its application

Abstract

The present invention discloses a SiO2@phosphate glass lubricating additive for titanium alloy profile extrusion and its application. The preparation method of the SiO2@phosphate glass lubricant is to mix modified phosphate glass powder, SiO2 colloidal solution and toluene, and then stir magnetically, and wash the stirred solution with acetone, ethanol and distilled water to obtain the SiO2@phosphate glass lubricating additive. The application of the SiO2@phosphate glass lubricant is to prepare a glass lubricant for titanium alloy profile extrusion. The lubricant for titanium alloy profile extrusion prepared by using the glass lubricating additive of the present invention has excellent and stable lubrication in the temperature range of 800-950°C, and has a low friction coefficient (0.1-0.18), excellent lubrication effect, and can effectively reduce cracks on the surface of the titanium alloy and improve its surface quality.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricants, and in particular relates to a SiO2@phosphate glass lubricant for titanium alloy profile extrusion and application thereof. Background Art

[0002] Titanium alloy, a key strategic metal, boasts excellent mechanical properties such as high specific strength, biocompatible properties, strong corrosion resistance, and low density. It is an indispensable key material for modern high-tech applications, often referred to as "space metal" and "ocean metal." Currently, titanium alloys enjoy broad application prospects, widely used in aerospace, military, marine engineering, biomedical, and other fields, and are a key raw material for China's pursuit of high-end manufacturing power.

[0003] Titanium alloys can be categorized into four main types based on their material form: sheets, profiles, tubes, and wires. Processing methods include forging, rolling, extrusion, and drawing. Currently, extrusion is the primary method for producing industrial-pure titanium tubes, bars, and profiles. Hot extrusion is performed under high temperature and high pressure. Industrial-pure titanium, which is chemically active and has poor thermal conductivity, is prone to air pollution and die adhesion during hot extrusion, increasing die wear and extrusion energy consumption. Furthermore, the temperature difference between the surface and center of the titanium billet causes uneven metal flow, reducing the billet's surface quality. Lubricants are a key technical step in solving the extrusion problems of industrial-pure titanium. There are three main types of lubricants: grease, glass lubricant, and metal cladding. Grease is only suitable for extruding shorter products, as it can cause sticking at the end. Metal cladding is a complex process that increases production costs. Acid washing is required after hot extrusion to remove impurities from the metal surface, which can cause environmental pollution. Glass lubricants, however, offer excellent chemical stability, low thermal conductivity, environmental friendliness, and high load-bearing capacity, making them the lubricant with the greatest potential for development in metal forming processes.

[0004] Glass lubricants are currently well-established in steel extrusion processes. Because the viscosity of glass lubricants is temperature-dependent, the viscosity affects their lubricating effectiveness, thereby altering the quality of the metal surface. Furthermore, the bonding strength between the glass lubricant and the substrate is related to the thermal expansion coefficient, which influences the substrate's oxidation resistance. Therefore, the hot extrusion temperature, the type of metal being processed, and the thermal expansion coefficient of the workpiece are key factors in determining the proper use of glass lubricants. Titanium alloys differ from steel in mechanical properties, making glass lubricants suitable for steel unsuitable for industrially pure titanium. Therefore, it is necessary to develop a high-temperature-resistant glass lubricant for titanium alloy extrusion. Summary of the Invention

[0005] The first object of the present invention is to provide a SiO2@phosphate glass lubricating additive for titanium alloy profile extrusion, and the second object of the present invention is to provide an application of the SiO2@phosphate glass lubricant for titanium alloy profile extrusion.

[0006] The first object of the present invention is achieved by providing a SiO2@phosphate glass lubricating additive for titanium alloy profile extrusion, wherein the preparation method of the SiO2@phosphate glass lubricating additive is achieved by the following steps:

[0007] 1) Mixing phosphate glass powder, stearic acid, and sodium hydroxide in a mass ratio of 1:(0.3-0.45):(1-1.5), adding distilled water to adjust the pH to 8-8.5, stirring at 50°C-60°C for 1 h-1.5 h, and then vacuum drying to obtain modified phosphate glass powder;

[0008] 2) Distilled water, 1.2 mol / L ammonia water, and 0.48 mol / L n-hexylamine are mixed in a volume ratio of 1:0.022:0.064, and a trace amount of ethanol is added. The mixture is magnetically stirred at a constant temperature of 30°C to 40°C for 10 min to 15 min. Subsequently, 0.3 mol / L to 0.36 mol / L tetraethyl orthosilicate is quickly added and magnetically stirred at 150 rpm to 200 rpm for 40 min to 50 min to obtain a SiO2 suspension. The obtained SiO2 suspension is distilled at 70°C to 80°C, and the purified SiO2 colloidal particles are diluted with distilled water and dispersed by centrifugation. This is repeated multiple times to obtain a SiO2 colloidal solution.

[0009] 3) The modified phosphate glass powder, the SiO2 colloidal solution and toluene are mixed and then magnetically stirred. The stirred solution is washed with acetone, ethanol and distilled water to obtain a SiO2@phosphate glass lubricating additive.

[0010] The second object of the present invention is achieved in that the SiO2@phosphate glass lubricating additive is used in the preparation of a glass lubricant for extrusion of titanium alloy profiles.

[0011] The phosphate glass powder prepared by the present invention has a wide temperature range of 750°C to 1100°C; titanium alloy begins to oxidize above 600°C, and the homemade glass powder has a low glass transition temperature (Tg) of about 420°C and a softening temperature of about 530°C, which can play a good antioxidant role on titanium alloy.

[0012] The present invention prepares a SiO2@phosphate glass lubricating emulsion by modifying phosphate glass powder and stirring and emulsifying it with a nano-oxide SiO2 colloidal solution at high speed, thereby improving the dispersibility of a single glass lubricant, enhancing the lubricating performance of a single phosphate lubricant, and avoiding the problem of single nano-oxide particles acting as abrasive particles and increasing abrasive wear of the friction pair due to the addition of the particles.

[0013] The present invention prepares a SiO2@phosphate glass lubricant additive by modifying phosphate glass powder and emulsifying it with a nano-oxide SiO2 colloidal solution through high-speed stirring. The prepared glass lubricant easily solidifies at low temperatures. Compared with the single glass lubricant commonly used in factories, the presence of crystals not only reduces the glass lubricant's adhesion, improving its lubrication performance, but also reduces the lubricant's expansion coefficient at high temperatures, promoting good adhesion between the molten coating and the substrate. When the glass lubricant coating temperature is below approximately 470°C (as observed experimentally), the coating also facilitates flaking when oxidation of the titanium alloy begins, improving the lubricant's oxidation resistance and facilitating cleaning during hot working. Furthermore, the SiO2 colloidal solution prepared in this invention comprises spherical nanoparticles, which, when mixed with molten glass, produce a synergistic lubrication effect that provides excellent friction reduction and anti-wear properties.

[0014] The lubricant prepared by using the glass lubricating additive of the present invention has excellent and stable lubrication in the temperature range of 800-950°C, and has a low friction coefficient (0.1-0.8). It has excellent lubrication effect, can effectively reduce cracks on the surface of titanium alloy, and improve its surface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Flow chart for preparing the glass lubricating additive according to Example 4;

[0016] Figure 2 This is a scanning electron microscope image of the phosphate glass powder prepared in Example 3;

[0017] Figure 3 This is a scanning electron microscope image of the silica colloidal solution prepared in Example 4;

[0018] Figure 4 This is a picture of the original state of the glass lubricant prepared in Example 4 attached to the titanium alloy surface;

[0019] Figure 5 Thermogravimetric-differential thermal curve of the glass powder prepared in Example 4;

[0020] Figure 6 The tribological curves of the phosphoric acid glass lubricants prepared in Examples 1 to 3 after a high-temperature friction test at an experimental temperature of 800°C are shown;

[0021] Figure 7 The average friction coefficient and wear rate of the phosphate glass lubricant prepared in Examples 1 to 3 in a high-temperature friction test at 800°C;

[0022] Figure 8 The tribological curves of the glass lubricants prepared in Comparative Example 1 and Examples 4 to 6 after high-temperature friction tests at an experimental temperature of 800°C are shown;

[0023] Figure 9These are tribological curves of the glass lubricants prepared in Example 4 and Comparative Examples 1 to 3 after a high-temperature friction test at an experimental temperature of 800°C.

[0024] Figure 10 The coating peeling condition of the glass lubricant prepared in Example 4 at 800°C;

[0025] Figure 11 These are tribological curves of the glass lubricants prepared in Example 4 and Comparative Example 4 after a high-temperature friction test at an experimental temperature of 800°C.

[0026] Figure 12 These are tribological curves of the glass lubricants prepared in Example 4 and Comparative Example 4 after undergoing a high-temperature friction test at an experimental temperature of 850°C.

[0027] Figure 13 These are tribological curves of the glass lubricants prepared in Example 4 and Comparative Example 4 after a high-temperature friction test at 900°C.

[0028] Figure 14 These are tribological curves of the glass lubricants prepared in Example 4 and Comparative Example 4 after undergoing a high-temperature friction test at an experimental temperature of 950°C. DETAILED DESCRIPTION

[0029] The present invention is further described below, but is not intended to limit the present invention in any way. Any changes made based on the present invention fall within the scope of protection of the present invention.

[0030] The present invention provides a SiO2@phosphate glass lubricating additive for titanium alloy profile extrusion. The preparation method of the SiO2@phosphate glass lubricating additive is achieved by the following steps:

[0031] 1) Mixing phosphate glass powder, stearic acid, and sodium hydroxide in a mass ratio of 1:(0.3-0.45):(1-1.5), adding distilled water to adjust the pH to 8-8.5, stirring at 50°C-60°C for 1 h-1.5 h, and then vacuum drying to obtain modified phosphate glass powder;

[0032] 2) Distilled water, 1.2 mol / L ammonia water, and 0.48 mol / L n-hexylamine are mixed in a volume ratio of 1:0.022:0.064, and a trace amount of ethanol is added. The mixture is magnetically stirred at a constant temperature of 30°C to 40°C for 10 to 15 minutes. Subsequently, 0.3 mol / L to 0.36 mol / L tetraethyl orthosilicate is quickly added and magnetically stirred at 150 rpm to 200 rpm for 40 to 50 minutes to obtain a SiO2 suspension. The obtained SiO2 suspension is distilled at 70°C to 80°C, and the purified SiO2 colloidal particles are diluted with distilled water and dispersed by centrifugation. This is repeated multiple times to obtain a SiO2 colloidal solution.

[0033] 3) The modified phosphate glass powder, the SiO2 colloidal solution and toluene are mixed and then magnetically stirred. The stirred solution is washed with acetone, ethanol and distilled water to obtain a SiO2@phosphate glass lubricating additive.

[0034] In step 1), the vacuum drying temperature is 50°C to 70°C, and the drying time is 9h to 12h.

[0035] In step 3), the mass ratio of toluene, modified phosphate glass powder and SiO2 colloidal solution is 1:(0.046~0.08):(1.193~2.393).

[0036] In step 3), the stirring speed is 850 r / min~950 r / min, and the stirring time is 2 h~3 h.

[0037] In step 1), the phosphate glass powder is prepared by adding 40-70 parts of phosphorus pentoxide, 5-12 parts of sodium oxide, 6-14 parts of calcium oxide, 4-16 parts of magnesium oxide, 8-15 parts of lithium oxide, and 10-15 parts of titanium oxide into a crucible, heating the mixture in an electronic furnace at 1250° C. for 3 hours to perform a high-temperature and high-pressure reaction to obtain molten glass, quenching the mixture in a water bath to obtain a primary glass product, and ball milling the resulting product at 350 r / min-400 r / min for 25 h-30 h, followed by sieving to obtain phosphate glass powder.

[0038] The SiO2@phosphate glass lubricating additive has suitable flow properties and its operating temperature is as high as 1150°C.

[0039] The present invention also provides an application of the SiO2@phosphate glass lubricating additive, which is an application in preparing a glass lubricant for extruding titanium alloy profiles.

[0040] The preparation method of the glass lubricant comprises the following steps: adding a binder and distilled water to the SiO2@phosphate glass lubricant additive, mixing the mixture, and ultrasonicating the mixture for 35 to 45 minutes at an ultrasonic power of 280W to 350W; then slowly adding a dispersant, and magnetically stirring the mixture at 45°C to 65°C for 70 to 85 minutes to obtain the target SiO2@phosphate glass lubricant.

[0041] The binder is sodium silicate, and the dispersant is sodium dodecylbenzenesulfonate.

[0042] The mass ratio of SiO2@phosphate glass lubricating additive to distilled water, sodium silicate, and sodium dodecylbenzenesulfonate is 1:(6~10):(0.1~0.18):(0.01~0.1).

[0043] The raw materials used in the following embodiments of the present invention are: phosphate glass powder, homemade; stearic acid, commercially available; sodium hydroxide, commercially available; ethanol, commercially available; ammonia water, commercially available; n-hexylamine, commercially available; ethyl orthosilicate, commercially available; acetone, commercially available; sodium silicate binder, commercially available; sodium dodecylbenzenesulfonate dispersant, commercially available; and distilled water, commercially available.

[0044] Example 1

[0045] 72.9g of ammonium dihydrogen phosphate, 15.3g of sodium carbonate, 22.32g of calcium carbonate, 7.25g of magnesium hydroxide, 28.36g of lithium carbonate, and 1.8g of titanium oxide were placed in a corundum crucible and heated in a box furnace at 1250°C for 3 hours. After quenching in a water bath, the mixture was dried, ball-milled at 400 rpm for 25 hours, and sieved to obtain phosphate glass powder. 0.5g of phosphate glass powder was added to 3mL of distilled water and stirred at 35°C for 25 minutes to obtain a phosphate glass lubricant.

[0046] Example 2

[0047] 52.64g of ammonium dihydrogen phosphate, 39.32g of sodium carbonate, 46.42g of calcium carbonate, 13.05g of magnesium hydroxide, 39.47g of lithium carbonate, and 6g of titanium oxide were placed in a corundum crucible and heated in a box furnace at 1250°C for 3 hours. After quenching in a water bath, the mixture was dried, ball-milled at 350 rpm for 30 hours, and sieved to obtain phosphate glass powder. 0.5g of phosphate glass powder was added to 3mL of distilled water and stirred at 35°C for 25 minutes to obtain a phosphate glass lubricant.

[0048] Example 3

[0049] 44.54 g of ammonium dihydrogen phosphate, 30.77 g of sodium carbonate, 31.25 g of calcium carbonate, 10.875 g of magnesium hydroxide, 34.53 g of lithium carbonate, and 4 g of titanium oxide were placed in a corundum crucible, heated in a box furnace at 1250°C for 3 hours, quenched in a water bath, dried, ball-milled at a speed of 375 r / min for 27 hours, and sieved to obtain phosphate glass powder. Figure 2 It can be seen that the phosphate glass powder prepared by high temperature quenching and ball milling has a uniform size distribution. Phosphate glass lubricant is prepared by stirring 0.5g of phosphate glass powder and 3mL of distilled water at 35℃ for 25min.

[0050] from Figure 6 and Figure 7 It can be seen that the friction coefficient of the phosphate glass powder prepared in Example 1 is relatively unstable in the first 150s, with an average friction coefficient of 0.32 and a wear rate of 1.68×10 -7 mm 3 N -1 m -1 The friction coefficient of the phosphate glass powder prepared in Example 2 was stable at the beginning, and then decreased rapidly after 250 seconds. This was because the viscosity of the glass was low, and the wear parts were exposed during the friction process, allowing the glass to flow into them. It was also possible that the machine was in a protective state and no load was applied, resulting in idling. However, its average friction coefficient was 0.29, and the wear rate was 1.61×10 -7 mm 3 N -1 m -1 The friction system of Example 3 was in the running-in stage before 100s, and then it became stable with a friction coefficient of 0.27 and a wear rate of 1.36×10 -7 mm 3 N -1 m -1 Therefore, the homemade phosphate glass powder in Example 3 was used in subsequent experiments.

[0051] Example 4

[0052] Take 20 parts of the phosphate glass powder prepared in Example 3, 7 parts of stearic acid, and 2.4 parts of sodium hydroxide, then add distilled water to adjust the pH to 8-8.5, place in a sealed beaker at 55°C and mix and stir for 1.3 hours to obtain solution A, place solution A in a vacuum drying oven at 55°C for 11 hours, and then grind to obtain the modified phosphate glass powder.

[0053] Take 10mL of distilled water, 0.012mL of 1.2mol / L ammonia water, and 0.64mL of 0.48mol / L n-hexylamine and place them in a beaker at 35℃ and stir them magnetically for 13min. During this process, add a small amount of ethanol, and then quickly add 0.7g of TEOS. Stir magnetically at 180r / min for 45min to obtain SiO2 suspension, which is then distilled, diluted, and rinsed several times to obtain SiO2 colloidal solution. Figure 3 It can be seen that the silica generated by depolymerization of TEOS is spherical nanoparticles.

[0054] 0.6 g of modified phosphate glass powder was mixed evenly with 10 mL of toluene solution by ultrasonic mixing in a water bath. 3 mL of SiO2 colloidal solution was used as the dispersed phase. The modified phosphate glass powder was suspended in the toluene solution by high-speed shearing at a speed of 900 r / min for 2.5 h to obtain SiO2@phosphate glass lubricating additive. 0.5 g of SiO2@phosphate glass lubricating additive and 4 mL of distilled water were added to 0.07 g of sodium silicate binder and ultrasonicated at 330 W power for 40 min. 0.04 g of sodium dodecylbenzenesulfonate dispersant was slowly added, followed by magnetic stirring at 55 ° C for 75 min to obtain a glass lubricant.

[0055] Example 5

[0056] Take 20 parts of the phosphate glass powder prepared in Example 3, 6 parts of stearic acid, and 2 parts of sodium hydroxide, then add distilled water to adjust the pH to 8-8.5, place in a sealed beaker at 50°C and mix and stir for 1 hour to obtain solution A, place solution A in a vacuum drying oven at 50°C for 9 hours, and then grind to obtain the modified phosphate glass powder.

[0057] Take 10mL of distilled water, 0.012mL of 1.2mol / L ammonia water, and 0.64mL of 0.48mol / L n-hexylamine and place them in a beaker at 35℃ and stir them magnetically for 13min. During this process, add a small amount of ethanol, and then quickly add 0.62g of TEOS. Stir magnetically at 150r / min for 40min to obtain SiO2 suspension, which is then distilled, diluted, and rinsed several times to obtain SiO2 colloidal solution. Figure 3 It can be seen that the silica generated by depolymerization of TEOS is spherical nanoparticles.

[0058] 0.46 g of modified phosphate glass powder was mixed evenly with 10 mL of toluene solution by ultrasonic mixing in a water bath. 2 mL of SiO2 colloidal solution was used as the dispersed phase. The modified phosphate glass powder was suspended in the toluene solution at a high speed of 900 r / min for 2.5 h to obtain SiO2@phosphate glass lubricating additive. 0.5 g of SiO2@phosphate glass lubricating additive and 3 mL of distilled water were added to 0.05 g of sodium silicate binder and ultrasonicated at 280 W power for 35 min. 0.025 g of sodium dodecylbenzenesulfonate dispersant was slowly added, followed by magnetic stirring at 45 ° C for 70 min to obtain a glass lubricant.

[0059] Example 6

[0060] Take 20 parts of the phosphate glass powder of Example 3, 9 parts of stearic acid, and 3 parts of sodium hydroxide, then add distilled water to adjust the pH to 8-8.5, place in a sealed beaker at 60°C and mix and stir for 1.5 hours to obtain solution A, place solution A in a vacuum drying oven at 70°C for 12 hours, and then grind to obtain the modified phosphate glass powder.

[0061] Take 10mL of distilled water, 0.012mL of 1.2mol / L ammonia water, and 0.64mL of 48mol / L n-hexylamine and place them in a beaker at 35℃ and stir them magnetically for 13min. During this process, add a small amount of ethanol, and then quickly add 0.75g of TEOS. Stir magnetically at 200r / min for 50min to obtain SiO2 suspension, which is then distilled, diluted, and rinsed several times to obtain SiO2 colloidal solution. Figure 3 It can be seen that the silica generated by depolymerization of TEOS is spherical nanoparticles.

[0062] 0.8 g of modified phosphate glass powder was mixed evenly with 10 mL of toluene solution by ultrasonic mixing in a water bath. 4 mL of SiO2 colloidal solution was used as the dispersed phase. The modified phosphate glass powder was suspended in the toluene solution at a high speed of 950 r / min and sheared for 3 hours to obtain SiO2@phosphate glass lubricating additive. 0.5 g of SiO2@phosphate glass lubricating additive and 5 mL of distilled water were added to 0.09 g of sodium silicate binder and ultrasonicated at 350 W power for 45 minutes. 0.05 g of sodium dodecylbenzenesulfonate dispersant was slowly added, followed by magnetic stirring at 65 ° C for 85 minutes to obtain a glass lubricant.

[0063] Comparative Example 1

[0064] This comparative example is a blank control of Example 4, except that this comparative example does not have a lubricating coating.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 4 is that the lubricating additive in this comparative example is a nano-SiO2 colloidal solution.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 4 is that the lubricating additive in this comparative example is phosphate glass.

[0069] Comparative Example 4

[0070] This comparative example is compared with Example 4, except that the comparative lubricant is Oxylub-401 purchased from Stent, and other conditions remain unchanged.

[0071] Test example: High temperature friction test

[0072] The surface of the Ti-6Al-4V titanium alloy disc was cleaned with ethanol and petroleum ether and dried in a vacuum drying oven at 60°C. The phosphate glass powder prepared in Examples 1 to 3 and the lubricants prepared in Examples 4 to 6 and Comparative Examples 1 to 4 were then sprayed onto the surface of the Ti-6Al-4V titanium alloy disc, respectively. After drying at room temperature, a friction test was performed on a high temperature friction and wear testing machine (RTEC) at a speed of 30 r / min and a test time of 300 s.

[0073] Result analysis:

[0074] from Figure 4 It can be seen that the glass lubricant prepared in Example 4 adheres to the surface of the titanium alloy, and the lubricating coating is smoothly and evenly attached to the sample surface without any cracks, pores or bubbles. Figure 5 It can be seen that the glass powder prepared in Example 3 has a very small loss of only 4.46% at 0-1125°C, indicating that the glass powder in Example 3 has good thermal stability. According to the differential thermal curve analysis, the glass transition temperature (Tg) of the glass powder in Example 3 is about 420°C, and the softening temperature is about 530°C. In the temperature range of 750-1100°C, the glass powder in Example 3 is always in an exothermic stable state, indicating that it has a good melting range.

[0075] from Figure 8 It can be seen that compared with the dry friction of Comparative Example 1, the glass lubricants in Examples 4 to 6 can significantly reduce the friction coefficient. Among them, the average friction coefficient of the glass lubricant prepared in Example 4 is the best, basically maintained at 0.12, and the friction curve fluctuates only during the running-in period and then operates stably (such as Figure 10 (As shown, after friction cooling, the coating surface partially peels off, revealing a bright titanium alloy surface.) The average friction coefficient of the uncoated lubricant is 0.62, and the friction coefficient is always in a fluctuating stage, indicating that the glass lubricant prepared in Example 4 has a good friction reduction effect.

[0076] from Figure 9 It can be seen that the average friction coefficient of dry friction in Comparative Example 1 is relatively high, while the friction coefficient of the lubricant using only nano-SiO2 colloidal solution as a lubricating additive (Comparative Example 2) varies widely and is relatively large. The friction coefficient of the lubricant using only phosphate glass (Comparative Example 3 is also Example 3) as a lubricating additive is lower than that of dry friction (Comparative Example 1), and the average friction coefficient of the glass lubricant prepared in Example 4 is significantly lower than that of Comparative Examples 1 to 3.

[0077] Observe the coating peeling of Example 4 at 800℃ (the sample should be taken out at less than 200℃ after high temperature friction, and the process of coating peeling cannot be observed. Therefore, after heat treatment at the same temperature and holding time, it is taken out for observation). Figure 10 As shown in Figure a, cracks still appeared in the coating after 20 minutes, at which time the surface temperature of the coating was already lower than 500°C. Large-scale peeling occurred at 28 minutes, indicating that the glass lubricant in Example 4 not only has the function of preventing the surface oxidation of the titanium alloy, but also has the function of facilitating the surface cleaning of the titanium alloy after extrusion.

[0078] from Figures 11-14 It can be seen that the friction curves of the glass lubricant prepared in Example 4 at different temperatures are lower than those of the comparative example 4, i.e., the Stent glass lubricant, and the friction curve is relatively stable. The friction coefficients of Example 4 are all between 0.1 and 0.18, while the friction coefficients of the comparative example 4 are all greater than 0.22.

Claims

1. A SiO2@phosphate glass lubricating additive for titanium alloy profile extrusion, characterized in that: The preparation method of the SiO2@phosphate glass lubricating additive is achieved by the following steps: 1) Mixing phosphate glass powder, stearic acid, and sodium hydroxide in a mass ratio of 1:(0.3-0.45):(1-1.5), adding distilled water to adjust the pH to 8-8.5, stirring at 50°C-60°C for 1 h-1.5 h, and then vacuum drying to obtain modified phosphate glass powder; 2) Distilled water, 1.2 mol / L ammonia water, and 0.48 mol / L n-hexylamine are mixed in a volume ratio of 1:0.022:0.064, and a trace amount of ethanol is added. The mixture is magnetically stirred at a constant temperature of 30°C to 40°C for 10 to 15 minutes. Subsequently, 0.3 mol / L to 0.36 mol / L tetraethyl orthosilicate is quickly added and magnetically stirred at 150 rpm to 200 rpm for 40 to 50 minutes to obtain a SiO2 suspension. The obtained SiO2 suspension is distilled at 70°C to 80°C, and the purified SiO2 colloidal particles are diluted with distilled water and dispersed by centrifugation. This is repeated multiple times to obtain a SiO2 colloidal solution. 3) The modified phosphate glass powder, the SiO2 colloidal solution and toluene are mixed and then magnetically stirred. The stirred solution is washed with acetone, ethanol and distilled water to obtain a SiO2@phosphate glass lubricating additive.

2. The SiO2@phosphate glass lubricating additive according to claim 1, characterized in that: In step 1), the vacuum drying temperature is 50°C to 70°C, and the drying time is 9h to 12h.

3. The SiO2@phosphate glass lubricating additive according to claim 1, characterized in that: In step 3), the mass ratio of toluene, modified phosphate glass powder and SiO2 colloidal solution is 1:(0.046~0.08):(1.193~2.393).

4. The SiO2@phosphate glass lubricating additive according to claim 1, characterized in that: In step 3), the stirring speed is 850 r / min~950 r / min, and the stirring time is 2 h~3 h.

5. The SiO2@phosphate glass lubricating additive according to claim 1, characterized in that: The phosphate glass powder in step 1) is prepared by placing 44.54 g of ammonium dihydrogen phosphate, 30.77 g of sodium carbonate, 31.25 g of calcium carbonate, 10.875 g of magnesium hydroxide, 34.53 g of lithium carbonate, and 4 g of titanium oxide into a corundum crucible, heating the mixture in a box furnace at 1250° C. for 3 hours, quenching the mixture in a water bath, drying the mixture, ball milling the mixture at 375 r / min for 27 hours, and sieving the mixture to obtain the phosphate glass powder.

6. The SiO2@phosphate glass lubricating additive according to claim 1, characterized in that: The SiO2@phosphate glass lubricating additive has suitable flow properties and its operating temperature is as high as 1150°C.

7. Use of the SiO2@phosphate glass lubricating additive according to any one of claims 1 to 6 in preparing a glass lubricant for titanium alloy profile extrusion.

8. The application according to claim 7, characterized in that: The preparation method of the glass lubricant comprises the following steps: adding a binder and distilled water to the SiO2@phosphate glass lubricant additive, mixing the mixture, and ultrasonicating the mixture for 35 to 45 minutes at an ultrasonic power of 280W to 350W; then slowly adding a dispersant, and magnetically stirring the mixture at 45°C to 65°C for 70 to 85 minutes to obtain the target SiO2@phosphate glass lubricant.

9. The application according to claim 8, characterized in that: The binder is sodium silicate, and the dispersant is sodium dodecylbenzenesulfonate.

10. The application according to claim 9, characterized in that: The mass ratio of SiO2@phosphate glass lubricating additive to distilled water, sodium silicate, and sodium dodecylbenzenesulfonate is 1:(6~10):(0.1~0.18):(0.01~0.1).

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