Metal sulfide and application thereof

Abstract

The invention discloses a metal sulfide and application thereof, and relates to the technical field of sulfides. The metal sulfide disclosed by the invention is a zinc sulfide material, and the zinc sulfide material meets the following relational expression: span * ((I1 + I3) / I2) is more than or equal to 0.2 and less than or equal to 6.3; wherein span is the particle size distribution span value of the zinc sulfide material; i1, I2 and I3 respectively represent the peak intensities of diffraction peaks at the positions of 26.7 to 27.1 degrees, 28.4 to 28.8 degrees and 30.4 to 30.8 degrees in an XRD (X-Ray Diffraction) spectrum of the zinc sulfide material obtained by XRD measurement. The metal sulfide disclosed by the invention is applied to the friction material, so that the friction coefficient change rate of the friction material in extreme environments such as low temperature and high temperature is small, and the wear rate is relatively low.

Description

[0001] This application is a divisional application of CN119320160A (with an application date of December 19, 2024, an application number of 202411875710.9, and an invention-creation name of "A Metal Sulfide and Its Application"). Technical Field

[0002] The present invention relates to the technical field of sulfides, and specifically relates to a metal sulfide and its application. Background Art

[0003] In an automotive braking system, brake pads are a crucial component, directly affecting the braking performance and safety of the vehicle. The performance requirements of brake pads reach certain standards in terms of friction coefficient, wear resistance, etc., to ensure stable and reliable braking effect of the vehicle.

[0004] In the design of brake pads, the friction coefficient is a crucial parameter. Generally, the friction coefficient of ordinary brake pads is about between 0.3 and 0.4, while that of high-performance brake pads is between 0.4 and 0.5. For brake pads with a higher friction coefficient, when the vehicle brakes, only a smaller hydraulic pressure (i.e., a smaller stepping force) needs to be applied to generate a larger braking force, thus achieving a more excellent braking effect. However, when the friction coefficient is relatively high, it means that the surface roughness of the friction material increases, which may cause noise problems. More seriously, it leads to an increase in friction loss, and further makes the material not wear-resistant and the friction performance deteriorate.

[0005] To solve this problem, lubricants are usually considered to be added to reduce friction loss. For example, in the prior art CN102713334B, a friction material for brakes is disclosed, which includes lubricants, and the lubricants can be metal sulfides. However, in actual applications, especially in extreme environments, adding lubricants may reduce the braking performance of brake pads.

[0006] In extreme environments, such as when operating continuously at high or low temperatures, the friction coefficient of brake pads often shows a downward trend, thus affecting the braking effect of the vehicle. For example, when braking for a long time at high speeds, the temperature will be too high, causing the friction coefficient of the friction material to drop rapidly; at low temperatures, the friction coefficient may be too low, and the vehicle can only increase the preheating time to make the brake pads reach the working temperature to avoid initial braking failure, resulting in a decrease in driving safety and comfort. The braking performance of the friction material added with lubricants is further reduced, exacerbating the instability of the braking system in extreme environments. Although the prior art CN 103644228A reports that zinc sulfide can replace resin to play a certain bonding role under humid and hot conditions, it does not solve the problem that the friction coefficient of brake pads still drops significantly at higher braking temperatures.

[0007] Therefore, it is necessary to develop a metal sulfide that can enable the friction material to maintain relatively stable braking performance in extreme environments such as low temperature and high temperature when applied to the friction material, so as to meet the high requirements of the braking system for safety, reliability and comfort. Summary of the Invention

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a metal sulfide and its application. By controlling the particle size distribution span value and crystal structure of the metal sulfide, when the metal sulfide is applied to the friction material, the friction material can maintain stable braking performance in extreme environments such as low temperature and high temperature, the change rate of the friction coefficient under high temperature and low temperature conditions is small, and the wear rate is relatively low.

[0009] To achieve the above object, in the first aspect of the present invention, the present invention provides a metal sulfide, the metal sulfide is a zinc sulfide material, and the zinc sulfide material satisfies the following relationship: 0.2 ≤ span × ((I 1 +I 3 ) / I 2 ) ≤ 6.3;

[0010] Wherein, the span is the particle size distribution span value of the zinc sulfide material;

[0011] The I 1 , I 2 , I 3 respectively represent the peak intensities of the diffraction peaks at the positions of 26.7 - 27.1°, 28.4 - 28.8°, and 30.4 - 30.8° in the XRD pattern obtained by XRD measurement of the zinc sulfide material.

[0012] As a metal sulfide, the zinc sulfide material has certain lubrication performance, which helps to reduce the friction loss of the friction material. However, for the existing brake pads added with zinc sulfide material, although the friction loss has been improved, it often causes the braking performance of the brake pads to decline in extreme environments, especially in low temperature environments, where the friction coefficient drops significantly.

[0013] The present invention studies and finds that by synergistically controlling the particle size distribution and crystal structure of the zinc sulfide material to make it satisfy the relationship: 0.2 ≤ span × ((I 1 +I 3 ) / I 2 ) ≤ 6.3, the morphology of zinc sulfide particles is comprehensively regulated from the macroscopic and microscopic perspectives, so that the friction material containing the metal sulfide has relatively high friction coefficients and low friction losses in high temperature and low temperature environments.

[0014] In the above relationship, the I 1 , I 2 , I 3respectively represent the peak intensities of the diffraction peaks at the positions of 26.7 - 27.1°, 28.4 - 28.8°, and 30.4 - 30.8° in the XRD pattern obtained by XRD measurement of the zinc sulfide material. That is, I 1 represents the peak intensity of the diffraction peak at 2θ = 26.7 - 27.1° in the XRD pattern of the zinc sulfide material, I 2 represents the peak intensity of the diffraction peak at 2θ = 28.4 - 28.8° in the XRD pattern of the zinc sulfide material, I 3 represents the peak intensity of the diffraction peak at 2θ = 30.4 - 30.8° in the XRD pattern of the zinc sulfide material.

[0015] In the XRD pattern of the zinc sulfide material, the diffraction peak at 2θ = 26.7 - 27.1° usually reflects the (100) crystal plane, the diffraction peak at 2θ = 28.4 - 28.8° reflects the (111) crystal plane, and the diffraction peak at 2θ = 30.4 - 30.8° reflects the (200) crystal plane.

[0016] The zinc sulfide material of the present invention has a crystal structure in which the wurtzite structure (also known as the hexagonal crystal system structure) and the sphalerite structure (also known as the cubic crystal system structure) coexist. Among them, the diffraction peak at 2θ = 28.4 - 28.8° is the characteristic peak of the cubic crystal system structure, and the diffraction peaks at 2θ = 26.7 - 27.1° and 2θ = 30.4 - 30.8° are the characteristic peaks of the hexagonal crystal system structure.

[0017] The present invention's research finds that due to the differences in crystal structure, there are certain differences in the performance effects of zinc sulfide with wurtzite structure and zinc sulfide with sphalerite structure in terms of friction and lubrication. Zinc sulfide with wurtzite structure is usually more wear-resistant than zinc sulfide with sphalerite structure; zinc sulfide with sphalerite structure may provide better lubrication performance; a specific content of zinc sulfide with sphalerite structure also helps to improve the friction coefficient of the brake pad material in the high-temperature and high-speed section. When simultaneously controlling I 1 、I 2 、I 3 to satisfy the said relational expression, the crystal structure of the zinc sulfide material is suitable, and the proportions of zinc sulfide with wurtzite structure and zinc sulfide with sphalerite structure are appropriate, enabling the friction material to maintain stable friction performance in extreme environments such as low temperature and high temperature.

[0018] The said span is the particle size distribution span value of the zinc sulfide material. The particle size distribution of the zinc sulfide material affects its surface characteristics and the interaction between particles, and thus affects the lubrication and friction performance of the zinc sulfide material.

[0019] The present invention comprehensively regulates the particle size distribution span value and crystal structure of zinc sulfide materials, and finds that there should be a certain matching between the span and its crystal structure. When the span is adapted to the crystal structure of zinc sulfide, the interaction between particles can be optimized, and the advantageous properties of zinc sulfide with a specific crystal structure can be enhanced, thus greatly improving the friction performance stability and friction loss of zinc sulfide materials.

[0020] When the zinc sulfide material satisfies 0.2 ≤ span × ((I 1 +I 3 ) / I 2 ), the friction coefficient change rate of the friction material containing the zinc sulfide material is low at high and low temperatures, and the friction loss is low, and the friction stability is significantly improved. When the value of span × ((I 1 +I 3 ) / I 2 ) exceeds the upper limit or is lower than the lower limit of the technical solution of the present invention, due to the difficulty in effectively matching the particle size distribution span value of zinc sulfide with the crystal structure, the friction coefficient change rate of the friction material containing the zinc sulfide material is too large at high and low temperatures, and due to poor material stability, the wear situation is also poor at high temperatures.

[0021] Preferably, the zinc sulfide material satisfies the following relationship: 1.8 ≤ span × ((I 1 +I 3 ) / I 2 ) ≤ 4.0.

[0022] When span × ((I 1 +I 3 ) / I 2 ) satisfies 1.8 to 4.0, the friction performance stability and friction loss of the friction material containing the zinc sulfide material are relatively better.

[0023] Preferably, the zinc sulfide material satisfies the following relationship: I 1 / I 3 ≥ 1.5.

[0024] More preferably, the zinc sulfide material satisfies the following relationship: 1.7 ≤ I 1 / I 3 ≤ 4.3.

[0025] Preferably, the zinc sulfide material satisfies the following relationship: 0.4 ≤ I 4 / I 2 ≤ 2.0;

[0026] wherein, the I 4 represents the peak intensity of the diffraction peak at the position of 47.4 to 47.8° in the XRD pattern obtained by XRD measurement of the zinc sulfide material.

[0027] Said I 4 represents the peak intensity of the diffraction peak at 2θ = 47.4 - 47.8° in the XRD pattern of the zinc sulfide material. The diffraction peak at 2θ = 47.4 - 47.8° usually reflects the (220) crystal plane.

[0028] I 1 and I 3 The ratio of, and I 4 and I 2 The ratios of all reflect the crystal orientation ratio of the zinc sulfide material. Different crystal planes respectively represent the planes intercepted by the zinc sulfide material along different crystal axis directions. Since the surface energies of different crystal planes are different, the magnitude of the surface energy will affect the surface adsorption capacity and the interaction with other substances, thereby affecting the friction and lubrication properties. In addition, there are certain differences in the stability of different crystal planes. Especially in a low-temperature environment, the crystal structure may change, and different crystal planes may respond differently to temperature changes, resulting in changes in their surface energy or mechanical properties.

[0029] The present invention studies and finds that when I 1 / I 3 , I 4 / I 2 meet the above preferred ranges, the performance of the zinc sulfide material at low temperature is better, and the friction performance stability in the friction material is higher.

[0030] For the zinc sulfide material, I 1 , I 2 , I 3 , I 4 are related to its crystal structure characteristics. The crystal structure of zinc sulfide can be adjusted by conventional technical means to change I 1 , I 2 , I 3 , I 4 of the zinc sulfide material. For example, by adjusting the synthesis raw materials, synthesis reaction conditions, and calcination conditions of zinc sulfide, the crystal growth direction, growth rate of zinc sulfide, or the crystallization rate, crystallization degree, recrystallization situation, etc. of zinc sulfide can be controlled to obtain zinc sulfide materials with different crystal structures.

[0031] Preferably, the range of the span is 2.2 - 3.5.

[0032] The span represents (Dv90 - Dv10) / Dv50, where Dv10, Dv50, and Dv90 respectively represent the particle sizes corresponding to the cumulative volume distribution percentages of the zinc sulfide material reaching 10%, 50%, and 90%, and the unit is nm.

[0033] The present invention does not limit the detection methods of Dv10, Dv50 and Dv90. Those skilled in the art can detect the particle size distribution of the zinc sulfide material according to conventional technical means. For example, the particle size distribution laser diffraction method according to GB / T19077-2016 can be referred to and measured using a laser particle size analyzer, such as the OMEC LS-POP (9) laser particle size analyzer.

[0034] A smaller span means that the size distribution of zinc sulfide particles is more uniform, which helps to form a uniform lubricating film on the friction surface and improve the lubrication effect; zinc sulfide with a smaller span also helps to increase the contact area between it and other components in the friction material, interact more, and improve the overall performance of the friction material. However, the span of zinc sulfide material should not be too low. When the span is too low, that is, the particle size distribution of zinc sulfide material is too concentrated, the particle size variation range is small, which may reduce the adaptability of zinc sulfide particles under different stress and temperature conditions. In special environments, zinc sulfide with relatively uniform particle size may not be able to fully adapt to changes in external conditions, thereby affecting friction performance.

[0035] Preferably, the Dv50 of the zinc sulfide material is 550-850 nm. Within the above Dv50 range, the particle size of the zinc sulfide material is within an appropriate range, the overall particle size of the zinc sulfide material is not too large or too small, it can be well dispersed when added to the friction material, and the interface contact effect with other components in the friction material is good, which promotes the zinc sulfide material to effectively play its role in improving friction and lubrication performance.

[0036] For the Dv50 and span value of the zinc sulfide material, the zinc sulfide material with a specific particle size distribution can be obtained by crushing and screening the zinc sulfide material, or by selecting a commercially available zinc sulfide material with a suitable particle size.

[0037] Preferably, the ignition loss of the zinc sulfide material after heating at 950° C. for 3 hours is 16.8-18.2%.

[0038] The loss on ignition of zinc sulfide material is related to various factors. The level of the loss on ignition value, especially, is related to the crystal structure stability of the zinc sulfide material. The research of the present invention finds that under the condition of heating at 950 °C for 3 h, the loss on ignition is 16.8 - 18.2%, indicating that the zinc sulfide material has appropriate crystal structure stability, which is helpful for the high stability of the friction performance of the friction material containing the zinc sulfide material. The loss on ignition should not be too low. When the loss on ignition is too low, it may mean that the zinc sulfide material has too high hardness or brittleness, which instead leads to an increase in friction loss, especially a decrease in friction performance at low temperatures. In addition, zinc sulfide may undergo certain state changes at high temperatures to compensate for the performance loss of the resin in the brake material at high temperatures. If the loss on ignition is too low, it will also cause zinc sulfide to be difficult to play an effective role in compensating for the resin performance loss, thereby causing the friction coefficient of the friction material to decrease.

[0039] In addition to being affected by the crystal structure stability, the loss on ignition of the zinc sulfide material is also affected by the particle size of the zinc sulfide material, that is, the particle size distribution, which further affects the heat absorption of the zinc sulfide particles and thus the loss on ignition.

[0040] Preferably, in the XRD pattern obtained by XRD measurement of the zinc sulfide material, the full width at half maximum of the diffraction peak at the position of 28.4 - 28.8° is 0.16 - 0.30.

[0041] More preferably, in the XRD pattern obtained by XRD measurement of the zinc sulfide material, the full width at half maximum of the diffraction peak at the position of 28.4 - 28.8° is 0.18 - 0.295.

[0042] The full width at half maximum of the diffraction peak in the XRD pattern reflects the degree of defects and crystallinity in the crystal structure of the zinc sulfide material. A relatively small full width at half maximum of the diffraction peak indicates that the corresponding crystal structure of the zinc sulfide material has fewer defects and higher crystallinity, which may reflect higher crystal stability of the zinc sulfide material. However, the full width at half maximum of the diffraction peak should not be too low. The research of the present invention finds that an appropriate amount of crystal defects may increase the active sites on the material surface or improve the surface affinity, which may be helpful for improving the lubrication performance of the material. When the full width at half maximum of the above diffraction peak is too low, it will lead to an increase in the friction loss of the friction material containing the zinc sulfide material.

[0043] In the second aspect of the present invention, the present invention provides the application of metal sulfide in the preparation of friction materials.

[0044] Specifically, the friction material can be a brake pad.

[0045] In the third aspect of the present invention, the present invention provides a friction material, including 1 - 20 wt.% of the above-mentioned metal sulfide.

[0046] The friction material may further include a binder and a reinforcing material.

[0047] The binder can be selected from common binders in friction materials, such as at least one of phenolic resin, modified phenolic resin, and organosilicon-modified resin.

[0048] The reinforcing material can be selected from common reinforcing materials in friction materials, such as at least one of mineral fiber, steel fiber, carbon fiber, ceramic fiber, silicon nitride whisker, boride whisker, graphite, barium sulfate, mica powder, and calcium silicate.

[0049] The beneficial effects of the present invention are as follows:

[0050] The present invention provides a metal sulfide. By controlling the particle size distribution span value and crystal structure of the metal sulfide, when the metal sulfide is applied in a friction material, the friction material can maintain stable braking performance under extreme environments such as low temperature and high temperature. The change rate of the friction coefficient under high temperature and low temperature conditions is smaller than that under conventional use temperature conditions, and the friction loss is lower. Description of the Drawings

[0051] Figure 1 It is the XRD pattern of the zinc sulfide material prepared in Example 1 of this application.

[0052] Figure 2 It is the XRD pattern of the zinc sulfide material prepared in Example 2 of this application.

[0053] Figure 3 It is the XRD pattern of the zinc sulfide material prepared in Example 11 of this application. Detailed Embodiments

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0055] In the present invention, among the technically characterized described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0056] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0057] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0058] For the reagents or instruments used in the present invention, if the manufacturer is not specified, they are all conventional products that can be obtained through commercial purchase.

[0059] Unless otherwise specified, a certain component in the parallel examples and comparative examples of the present invention is the same commercially available product.

[0060] Example 1

[0061] Example 1 provides a zinc sulfide material. The preparation of the zinc sulfide material includes the following steps:

[0062] S1. Add a zinc source (zinc chloride), a sulfur source (thioacetamide), and a template agent (diethylenetriamine, DETA) to deionized water, and mix evenly to obtain a reaction solution; wherein the molar ratio of the zinc source to the sulfur source is controlled to be 1:1;

[0063] S2. Stir and react the above reaction solution at 60 °C at a speed of 300 rpm for 2 h, then transfer it to a reaction kettle and react at 280 °C for 15 h, take it out and place it at room temperature for cooling, filtration, washing with deionized water, and drying to obtain a pre-product;

[0064] S3. Calcinate the above pre-product: heat it from room temperature to 600 °C at a rate of 15 °C / min and calcine for 2 h, then heat it to 850 °C at a rate of 15 °C / min and calcine for another 30 min;

[0065] Place it at room temperature for cooling, wash it three times with deionized water, then filter, dry, crush and screen to obtain the zinc sulfide material with span and D as shown in Table 1 v 50.

[0066] Example 2

[0067] Example 2 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0068] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 650 °C at a rate of 12 °C / min and calcined for 1.5 h, then heated to 700 °C at a rate of 12 °C / min and calcined for another 60 min;

[0069] It is placed under room temperature conditions for cooling, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 zinc sulfide materials.

[0070] Example 3

[0071] Example 3 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0072] Step S2 is: The reaction solution prepared in S1 is stirred and reacted at 80 °C at a rotation speed of 180 rpm for 2 h, then transferred to a reaction kettle and reacted at 200 °C for 10 h, and then reacted at 300 °C for 2 h; taken out and placed under room temperature conditions for cooling, filtering, washing with deionized water, and drying to obtain a pre-product;

[0073] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 800 °C at a rate of 10 °C / min and calcined for 2 h;

[0074] It is placed under room temperature conditions for cooling, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 zinc sulfide materials.

[0075] Example 4

[0076] Example 4 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0077] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 500 °C at a rate of 10 °C / min and calcined for 3 h, then heated to 900 °C at a rate of 15 °C / min and calcined for another 60 min;

[0078] It is placed under room temperature conditions for cooling, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 zinc sulfide materials.

[0079] Example 5

[0080] Example 5 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0081] Step S3 includes the following steps: The pre-product is calcined under the following conditions: heated from room temperature to 680 °C at a rate of 8 °C / min and calcined for 2 h, then heated to 800 °C at a rate of 12 °C / min and calcined for another 45 min; after taking out, it is quickly immersed in deionized water for 60 s, taken out and placed at room temperature to cool, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 of zinc sulfide material.

[0082] Example 6

[0083] Example 6 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0084] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 800 °C at a rate of 15 °C / min and calcined for 4 h, then heated to 950 °C at a rate of 8 °C / min and calcined for another 30 min;

[0085] placed at room temperature to cool, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 of zinc sulfide material.

[0086] Example 7

[0087] Example 7 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0088] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 450 °C at a rate of 10 °C / min and calcined for 2.5 h, then heated to 800 °C at a rate of 10 °C / min and calcined for another 30 min;

[0089] placed at room temperature to cool, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as described in Table 1 v 50 of zinc sulfide material.

[0090] Example 8

[0091] Example 8 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0092] In step S2, the reaction solution is stirred and reacted at 80 °C at a rotation speed of 1000 rpm for 3 h, and then transferred to a reaction kettle and reacted at 200 °C for 10 h;

[0093] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 900 °C at a rate of 15 °C / min and calcined for 4 h;

[0094] After being placed at room temperature for cooling, washed three times with deionized water, filtered, dried, pulverized and sieved, the span and D as described in Table 1 were obtained. v 50 zinc sulfide materials.

[0095] Example 9

[0096] Example 9 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0097] In step S3, the pre-product was calcined under the following conditions: heated from room temperature to 500 °C at a rate of 5 °C / min and calcined for 3 h, then heated to 900 °C at a rate of 10 °C / min and calcined for another 120 min;

[0098] After being placed at room temperature for cooling, washed three times with deionized water, filtered, dried, pulverized and sieved, the span and D as described in Table 1 were obtained. v 50 zinc sulfide materials.

[0099] Example 10

[0100] Example 10 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0101] Step S2 is: The reaction solution prepared in S1 was stirred and reacted at 45 °C at a speed of 60 rpm for 10 h, and then stirred and reacted at 80 °C at a speed of 60 rpm for 4 h; then transferred to a reaction kettle and reacted at 180 °C for 20 h; taken out and placed at room temperature for cooling, filtered, washed with deionized water, and dried to obtain a pre-product;

[0102] In step S3, the product after calcination under the same calcination conditions as in Example 1 was pulverized and sieved to obtain the span and D as described in Table 1 v 50 zinc sulfide materials.

[0103] Example 11

[0104] Example 11 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0105] Step S2 is: The reaction solution prepared in S1 was stirred and reacted at 60 °C at a speed of 30 rpm for 8 h, and then stirred and reacted at 80 °C at a speed of 30 rpm for 8 h; then transferred to a reaction kettle and reacted at 200 °C for 18 h; taken out and placed at room temperature for cooling, filtered, washed with deionized water, and dried to obtain a pre-product;

[0106] In step S3, the product after calcination under the same calcination conditions as in Example 1 was pulverized and sieved to obtain the span and D as described in Table 1v Zinc sulfide material of 50.

[0107] Comparative Example 1

[0108] Comparative Example 1 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0109] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 850 °C at a rate of 20 °C / min and calcined for 6 h; after taking out, it is quickly immersed in deionized water for 30 s, then taken out and placed at room temperature to cool, washed three times with deionized water, filtered, dried, pulverized and sieved to obtain span and D as described in Table 1 v Zinc sulfide material of 50.

[0110] Comparative Example 2

[0111] Comparative Example 2 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0112] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 800 °C at a rate of 8 °C / min and calcined for 1 h, then heated to 900 °C at a rate of 10 °C / min and calcined for another 30 min, and then cooled to 600 °C at a rate of 10 °C / min and calcined for 1 h;

[0113] Placed at room temperature to cool, washed three times with deionized water, filtered, dried, pulverized and sieved to obtain span and D as described in Table 1 v Zinc sulfide material of 50.

[0114] Comparative Example 3

[0115] Comparative Example 3 provides a zinc sulfide material. The preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0116] In step S2, the reaction solution is stirred and reacted at 50 °C at a speed of 80 rpm for 2 h, then transferred to a reaction kettle and reacted at 300 °C for 8 h, taken out and placed at room temperature to cool, filtered, washed with deionized water, dried to obtain a pre-product;

[0117] In step S3, the pre-product is calcined under the following conditions: heated from room temperature to 700 °C at a rate of 15 °C / min and calcined for 1.5 h, then heated to 850 °C at a rate of 15 °C / min and calcined for another 2.5 h;

[0118] Placed at room temperature to cool, washed three times with deionized water, filtered, dried, pulverized and sieved to obtain span and D as described in Table 1 v Zinc sulfide material of 50.

[0119] Comparative Example 4

[0120] Comparative Example 4 provides a zinc sulfide material, and the preparation method of the zinc sulfide material is similar to that of Example 1, except that:

[0121] In step S3, the pre-product is calcined: heated from room temperature to 800 °C at a rate of 10 °C / min, and kept at a constant temperature for 30 min when reaching 500 °C, 600 °C, and 700 °C, and calcined at a constant temperature for 3 h when reaching 800 °C; placed at room temperature for cooling, washed three times with deionized water, then filtered, dried, crushed and sieved to obtain the span and D as shown in Table 1 v 50 of zinc sulfide material.

[0122] The XRD test was carried out on the prepared zinc sulfide material, and I 1 , I 2 , I 3 , I 4 were measured respectively, and the full width at half maximum of the diffraction peak at the position of 28.4 - 28.8° (denoted as F WHM2 ) was measured, and the values of (I 1 + I 3 ) / I 2 , I 1 / I 3 , I 4 / I 2 were calculated;

[0123] The conditions for the XRD test were: obtained by using an X-ray diffractometer, Cu-Kα ray, scanning range 15 - 80°, PEAK: 21-pts / Parabolic Filter, Threshold = 3.0, Cutoff = 0.1%, BG = 3 / 1.0, Peak-Top = Summi.

[0124] The loss on ignition test was carried out on the prepared zinc sulfide material, and the test conditions were: a certain amount of zinc sulfide was taken, and its mass was accurately weighed as m1; in an air atmosphere, the zinc sulfide material was heated at 950 °C for 3 h, cooled to room temperature, and then its mass was accurately weighed again as m2; the loss on ignition was calculated as = (m1 - m2) / m1 * 100%.

[0125] Specifically, the relevant test results and particle size distributions of the zinc sulfide materials in the examples and comparative examples are shown in Table 1. The XRD pattern of the zinc sulfide material in Example 1 is as shown in Figure 1 , where I 1 is 4449, I 2 is 6068, I 3 is 1964, I 4 is 4524; the XRD pattern of the zinc sulfide material in Example 2 is as shown inFigure 2 As shown, where I 1 is 5496, I 2 is 6319, I 3 is 3239, I 4 is 4910; The XRD pattern of the zinc sulfide material in Example 11 is as Figure 3 shown, where I 1 is 11696, I 2 is 6819, I 3 is 1913, I 4 is 12746.

[0126] Table 1

[0127]

[0128] After calculation, the formulas satisfied by each example and comparative example are shown in Table 2-1, Table 2-2 and Table 2-3.

[0129] Using the zinc sulfide materials prepared in each example and comparative example, friction materials were prepared respectively according to the following component contents (weight percentage):

[0130] Phenolic resin (Kunyi Resin Materials Company, KT-3640CRA) 20 wt.%, aramid fiber 15 wt.%, basalt fiber 25 wt.%, filler (mica powder and calcium silicate mixed in a weight ratio of 1:1) 30 wt.%, zinc sulfide material 10 wt.%.

[0131] The preparation method of the friction material is as follows:

[0132] After mixing phenolic resin, aramid fiber, basalt fiber, filler and zinc sulfide material, it is hot-pressed (temperature is 180 °C, pressure is 25 MPa, time is 8 minutes), and then heat-treated (temperature is 150 °C, heat treatment time is 12 hours) to obtain the friction material.

[0133] The friction performance of the friction material was detected, and the specific detection method is as follows:

[0134] Using the high and low temperature friction and wear testing machine of Fuller Instrument Technology (Shanghai) Co., Ltd., the friction coefficient and wear rate of the friction material were tested. The test sample of the friction material was cut into a cuboid of 30 mm × 30 mm × 8 mm, and the disc-block contact form was adopted. The material of the counter part was gray cast iron. The test load point was selected as 0.8 MPa, the disc rotation speed was selected as 500 r / min, the test temperatures of the friction coefficient were: -20 °C, 200 °C, 500 °C, and the test temperatures of the wear rate were: -20 °C, 500 °C; Each group of samples was tested 10 times in parallel and the average value was recorded;

[0135] The friction coefficients measured at -20°C, 200°C, and 500°C are denoted as μ1, μ0, and μ2 respectively. The change rate of the friction coefficient at low temperature is calculated as = (μ0 - μ1) / μ0 × 100%, and the change rate of the friction coefficient at high temperature is = (μ0 - μ2) / μ0 × 100%.

[0136] The wear rates measured at -20°C and 500°C are denoted as W -20 、W 500 , and the measurement unit is: ×10 -7 cm 3 / (N·m).

[0137] The test results are shown in Table 2-1, Table 2-2, and Table 2-3.

[0138] Table 2-1

[0139]

[0140]

[0141] Table 2-2

[0142]

[0143] Table 2-3

[0144]

[0145] It can be seen from Table 2-1, Table 2-2, and Table 2-3 that the zinc sulfide materials prepared in each embodiment of the present invention are applied to the friction material, which can effectively improve the change rate of the friction coefficient of the friction material, making the change rate of the friction coefficient of the friction material at high temperature ≤ 12.1%, the change rate of the friction coefficient at low temperature ≤ 20.3%, and the wear rate of the friction material at high and low temperatures ≤ 0.35.

[0146] According to Examples 1 to 6, it can be seen that when the zinc sulfide material further satisfies I 1 / I 3 ≥ 1.5 and / or 0.4 ≤ I 4 / I 2 ≤ 2.0, the change rate of the friction coefficient of the friction material is relatively lower, especially the change rate of the friction coefficient at low temperature is significantly improved.

[0147] According to Examples 1 to 3 and 7 to 8, it can be seen that when the span of the zinc sulfide material is within an appropriate range, the friction material can have both good change rate of the friction coefficient and low wear rate.

[0148] According to Embodiments 9 to 11, it can be seen that when the loss on ignition of the zinc sulfide material is too high, it may mean that the crystal structure of the zinc sulfide material is not suitable, resulting in an increase in friction loss at high temperatures and a relatively high change rate of the friction coefficient at high temperatures; when the loss on ignition of the zinc sulfide material is too low, the friction material not only has an increase in friction loss, but also has a relatively large change rate of the friction coefficient at low temperatures.

[0149] In the comparative example, when the value of span×((I 1 +I 3 ) / I 2 ) of the zinc sulfide material exceeds the range of 0.2 to 6.3, not only is the change rate of the friction coefficient too large at high and low temperatures, but also due to poor material stability, the wear rate at high temperatures is very high.

[0150] It should be noted that the addition amount of the zinc sulfide material can be adjusted according to the needs of the friction material. Optionally, in the friction material, the zinc sulfide material can be added in an amount of 1 to 20 wt.%.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A metal sulfide, characterized in that: The metal sulfide is a zinc sulfide material, and the zinc sulfide material satisfies the following relationship: 1.7≤I1 / I3≤4.3, and 0.4≤I4 / I2≤2.0; The I1, I2, I3, and I4 respectively represent the peak intensities of diffraction peaks at 26.7-27.1°, 28.4-28.8°, 30.4-30.8°, and 47.4-47.8° in the XRD spectrum of the zinc sulfide material obtained by XRD measurement.

2. The metal sulfide according to claim 1, characterized in that: The zinc sulfide material satisfies the following relationship: 1.7≤I1 / I3<3.

24.

3. The metal sulfide according to claim 1 or 2, characterized in that: The zinc sulfide material satisfies the following relationship: 0.2≤span×((I1+I3) / I2)≤6.3; Wherein, the span is the particle size distribution span value of the zinc sulfide material; span represents (Dv90-Dv10) / Dv50, wherein Dv10, Dv50, and Dv90 represent the particle sizes corresponding to when the volume cumulative distribution percentage of the zinc sulfide material reaches 10%, 50%, and 90%, respectively, and the unit is nm.

4. The metal sulfide according to claim 3, characterized in that: The zinc sulfide material satisfies the following relationship: 1.8≤span×((I1+I3) / I2)≤4.

0.

5. The metal sulfide according to claim 3, characterized in that: The span ranges from 2.2 to 3.

5.

6. The metal sulfide according to claim 3, characterized in that: The Dv50 of the zinc sulfide material is 550-850nm.

7. The metal sulfide according to claim 1, characterized in that: The ignition loss of the zinc sulfide material after heating at 950° C. for 3 hours is 16.8-18.2% by mass.

8. Use of the metal sulfide according to any one of claims 1 to 7 in the preparation of friction materials.

9. The use according to claim 8, characterized in that: The friction material is a brake pad.

10. A friction material, characterized in that: The invention comprises 1 to 20 wt. % of the metal sulfide according to any one of claims 1 to 7.

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