Lubricant

Abstract

This invention is based on [Formula I]Fe 2-a Zn a S b The present invention relates to a composition having the formula (wherein a is a number in the range of 0.2 ≤ a ≤ 1.8, b is a number in the range of 1.8 ≤ b ≤ 2.2, preferably in the range of 1.9 ≤ b ≤ 2.1, most preferably b = 2, a means the molar ratio of Zn in the overall composition, and b means the molar ratio of S in the overall composition), wherein the composition contains, as a lubricant, at least two different mixed crystalline phases of Fe, Zn, and S, as determined herein.

Description

[Technical Field]

[0001] This invention relates to a composition and its use as a lubricant. [Background technology]

[0002] Metal sulfides act as functional additives for friction linings. Their tribological properties are crucial to the functionality of friction pairs, increasing performance and extending the lifespan of moving parts. The braking effect must be immediate and smooth, without generating noise and / or vibration.

[0003] In current applications, most solid lubricants are applied as thin solid films to the sliding surfaces of various types of substrates, including metals, ceramics, or organic materials. For example, solid lubricants are often applied to friction materials used in commercially available automotive brake pads, which are primarily made from a family of non-asbestos organic (NAO) formulations. Such NAO formulations typically consist of a resin matrix, various types of fibers, filler components, and friction and wear modifiers, and may further contain small amounts of metallic elements.

[0004] In particular, metallic friction materials can be classified into all-metallic, low-metallic, and metalloidal alloys.

[0005] All-metal materials, for example, are used in racing cars and consist of sintered steel that contains no synthetic additives. For example, all-metal brake pads last longer, but require more force to decelerate the car and wear down the rotors faster.

[0006] Low-metal formulations, containing only 10-30% metal, are considered more durable and cost-effective than all-metal pads. These materials are common because they are harder than organic pads and produce less dust and noise than their semi-metallic alternatives.

[0007] Semi-metallic materials contain a blend of 30 - 65% metal - typically cut steel wire, iron powder, copper or graphite and an inorganic filler. However, semi-metallic formulations do not function at the same level as ceramic or low-metal formulations at lower temperatures.

[0008] Ceramic formulations include oxides, carbides, borides, non-ferrous metals and fibers. Ceramic materials are very robust and are ideal for high-performance vehicles, especially as they produce less dust than other brake pad types. These formulations provide excellent braking benefits but are usually considered expensive.

[0009] Another example is a hybrid material consisting of a combination of both low-metal and NAO formulations, which are also used as friction materials.

[0010] Generally, the purpose of using solid lubricants in friction linings is not to reduce friction but to stabilize the friction behavior over time, which results in a reduction of the grinding process as well as good effects on wear and vibration characteristics.

[0011] In particular, the stabilization of the coefficient of friction (CoF) suppresses the harmful dependency of the CoF, and thus greatly suppresses the braking efficiency with respect to temperature, pressure load, and speed.

[0012] Therefore, solid lubricants have been proven to be effective in increasing the performance of brakes in terms of providing friction stability, reducing wear at high temperatures without degrading friction performance, and minimizing noise, vibration and harshness (NVH).

[0013] Various solid lubricants are currently in use, with graphite and molybdenum disulfide (MoS2) being the most common solid lubricants.

[0014] MoS2 has long been known as a solid lubricant for forming a solid lubricant film between surfaces intended to slide against each other. MoS2 and other metal sulfides are also used to reduce surface friction, for example, as components of gliding compositions consisting mainly of polytetrafluoroethylene (PTFE), i.e., plain bearing half liners or slide bushings.

[0015] Metal sulfides are used as solid lubricants in various fields, namely in the manufacture of friction elements such as brake blocks, brake shoes, brakes, and clutch linings, not to prevent friction, but to induce it.

[0016] Additionally, tin sulfides (SnS and SnS2) are considered alternatives to other metal sulfides, but they are typically associated with high costs.

[0017] In particular, it is known that when certain binary and ternary metal sulfides are used as solid lubricants, they yield better performance results compared to monometallic sulfide mixtures of similar composition.

[0018] For example, US5958846 describes solid lubricants, particularly for friction linings, whose main component is a metal sulfide, including different binary and ternary metal sulfides such as Cu2FeSnS4, Cu2FeSn3S8, Cu3SnS4, Mn2SnS4, SnFe2S4, or Cu2TiS2.

[0019] WO95 / 25231 discloses an additive for a friction lining mixture, characterized by comprising a mixture of iron sulfide and a mixture of molybdenum and / or zinc and / or antimony and / or tungsten and / or titanium sulfide.

[0020] The known product "SLX 121," manufactured by Tribotecc®, is a solid lubricant primarily composed of Bi, Fe, and Zn sulfides. The lubricant can be used alone or in combination with other solid lubricants on disc brake pads, high-performance friction linings, and clutch facings to improve pad and disc wear. The product has a viscosity of 4.7 g / cm³. 3 It is characterized by having a typical density, a typical sieve residue of 9% (45 μm), and a typical volatile matter of 0.1% (at 105°C). This product does not exhibit a mixed crystalline phase of Fe, Zn, and S.

[0021] It has been found that metal pickup (MPU) is often observed when certain metal sulfides are used as solid lubricants. MPU is a problematic phenomenon in automobile disc brakes. MPU generally forms metal clumps on the surface of the brake pads. When brake pads have MPU, during braking they will cause groove wear on the disc rotor, generate brake noise, and degrade braking performance. MPU is a phenomenon that depends on many factors such as weather and overall road conditions, and therefore cannot be easily quantified.

[0022] Furthermore, such friction linings must be industrially produced at a reasonable cost.

[0023] For many years, attempts have been made to create synergistic mixtures with exceptional effects by combining various solid lubricants. However, so far, these combinations have not succeeded in achieving satisfactory performance in all aspects.

[0024] Furthermore, the components of solid lubricants disclosed in the latest technologies, particularly Sn-based sulfides, are associated with increased costs, resulting in high manufacturing costs for friction materials for manufacturers and expensive products for end consumers.

[0025] Further prior art relates to publications by Perricone et al. (Wear (2017) 396, 135-145), Frederici et al. (Wear (2019) 424, 40-47), and Sinha et al. (Ultramicroscopy (2021) 230) disclosing friction materials for brakes containing sphalerite (Zn,Fe)S in combination with other components such as graphite or SnS2.

[0026] In another publication, Xie et al. (Inorganic Chemistry Communications (2019) 111) disclose an FeS / ZnS composite prepared by coprecipitation, which can be attributed to a mixture of metal sulfides ZnS (hexagonal) and FeS (cubic).

[0027] In a further example, DiCarlo et al. (Journal of Solid State Chemistry (1990) 87, 2, 443-448) disclose the synthesis of iron-doped ZnS, ZnSe, and CdS products that are single-phase and crystallized in a cubic zincblende-type structure (ZnS).

[0028] In another example, CN100418192C discloses a method for synthesizing Fe-doped ZnS thin films, including hexagonal and cubic polycrystalline structures.

[0029] Furthermore, WO95 / 25231A1 describes brake linings containing FeS and ZnS in combination with tricalcium phosphate, graphite, and antimony sulfide.

[0030] Furthermore, EP0826022Al relates to a solid lubricant, particularly for friction linings, whose main component is a metal sulfide. [Overview of the project] [Problems that the invention aims to solve]

[0031] The compositions disclosed in the latest technologies do not meet all the requirements of braking performance, wear resistance, MPU behavior, and cost. Therefore, the object of the present invention is to provide a novel type of solid lubricant that has better friction and wear resistance and is made from raw materials that are less expensive than state-of-the-art materials. [Means for solving the problem]

[0032] The object of the present invention is formula I Fe 2-a Zn a S b I (In the formula, a is a number in the range 0.2 ≤ a ≤ 1.8, b is a number within the range of 1.8 ≤ b ≤ 2.2, preferably within the range of 1.9 ≤ b ≤ 2.1, and most preferably b = 2. (where a represents the molar ratio of Zn in the total composition, and b represents the molar ratio of S in the total composition) This can be solved by a composition containing at least two different mixed crystalline phases of Fe, Zn, and S.

[0033] The compositions disclosed herein are useful as lubricants.

[0034] Finally, the present invention relates to a method for producing the compositions disclosed herein.

[0035] Preferred embodiments of the present invention are defined in the dependent claims. [Brief explanation of the drawing]

[0036] [Figure 1a] The simplified AK-Master test results for the compositions of Example 1 and Comparative Example 1 are shown. [Figure 1b] The results of the pad wear test for the compositions of Example 1 and Comparative Example 1 are shown. [Figure 1c] The results of the disk wear test for the compositions of Example 1 and Comparative Example 1 are shown. [Figure 2a]The simplified AK-Master test results for the compositions of Example 1 and Comparative Example 2 are shown. [Figure 2b] The results of the pad wear tests for the compositions of Example 1 and Comparative Example 2 are shown. [Figure 2c] The results of the disc wear test for the compositions of Example 1 and Comparative Example 2 are shown. [Figure 3a] The simplified AK-Master test results for the compositions of Example 1 and Comparative Example 3 are shown. [Figure 3b] The results of the pad wear tests for the compositions of Example 1 and Comparative Example 3 are shown. [Figure 3c] The results of the disc wear test for the compositions of Example 1 and Comparative Example 3 are shown. [Figure 4a] Simplified AK-Master test results for the compositions of Example 1 and Comparative Example 4 are shown. [Figure 4b] The pad wear test results for the compositions of Example 1 and Comparative Example 4 are shown. [Figure 4c] The results of the disc wear test for the compositions of Example 1 and Comparative Example 4 are shown. [Figure 5a] The simplified AK-Master test results for the compositions of Example 1 and Comparative Example 5 are shown. [Figure 5b] The pad wear test results for the compositions of Example 1 and Comparative Example 5 are shown. [Figure 5c] The results of the disc wear test for the compositions of Example 1 and Comparative Example 5 are shown. [Figure 6] The XRD spectrum of the composition according to Example 1 of the present invention is shown. [Figure 7] The peaks related to the crystalline phase from an XRD database containing the crystalline phase of the composition according to Example 1 are shown. [Figure 8] The XRD spectrum of the composition according to Example 2 of the present invention is shown. [Figure 9] The peaks related to the crystalline phase from an XRD database containing the crystalline phase of the composition according to Example 2 are shown. [Figure 10] The XRD spectrum of the composition according to Example 3 of the present invention is shown. [Figure 11] The peaks related to the crystalline phase from an XRD database containing the crystalline phase of the composition according to Example 3 are shown. [Figure 12] The XRD spectrum of the composition according to Comparative Example 5 is shown. [Figure 13] The peaks related to the crystalline phase from an XRD database containing the crystalline phase of the composition according to Comparative Example 5 are shown. [Figure 14a] The average friction coefficient (μ) of the compositions from Example 1 and Comparative Example 1, determined by block wear tests up to a temperature of 500°C, is shown. [Figure 14b] The pad wear of the compositions from Example 1 and Comparative Example 1 up to a temperature of 500°C, as determined by block wear tests, is shown. [Figure 14c] The disc wear of the compositions according to Example 1 and Comparative Example 1 up to a temperature of 500°C, as determined by block wear tests, is shown. [Figure 15a] The pad wear test results for the compositions of Example 1 and Comparative Example 6 are shown. [Figure 15b] The results of the disc wear test for the compositions of Example 1 and Comparative Example 6 are shown. [Modes for carrying out the invention]

[0037] Surprisingly, the compositions according to the present invention were found to exhibit lower wear and better MPU properties compared to state-of-the-art tin-based lubricants or other binary or multi-metallic sulfides. It was also found that expensive tin-based lubricants can be replaced by the compositions according to the present invention.

[0038] In particular, brake pads manufactured with NAO formulations containing the composition of the present invention exhibit lower pad and disc wear in braking systems than tin-based materials, binary metal sulfides, and multi-metal sulfides, even at high operating temperatures exceeding 300°C.

[0039] Furthermore, preliminary analyses under equivalent conditions showed that brake pads having the composition of the present invention were more stable with respect to MPU compared to other Fe-based sulfides. These effects further minimize brake noise and increase braking performance. Surprisingly, it was also found that the composition of the present invention leads to CoF stabilization, thereby reducing the polishing process and having a positive effect on wear characteristics.

[0040] Therefore, the compositions of the present invention exhibit highly desirable properties that improve energy efficiency and component life during braking, as well as good comfort.

[0041] Furthermore, the compositions of the present invention may be characterized by a significantly lower price compared to Sn-based compositions.

[0042] The term "mixed crystalline phase" refers to a crystalline phase that is a mixture of at least two cationic metals (Fe and Zn) and one anionic element (S).

[0043] The presence of a crystalline phase can be detected by XRD analysis (as further disclosed below), by comparing the resulting pattern with the patterns of known crystalline phases containing the element under consideration.

[0044] Composition according to the present invention, Formula I Fe 2-a Zn a S b I It belongs to them. "a" represents the molar ratio of Zn in the overall composition. "b" represents the molar ratio of S in the overall composition. a and b are as defined above.

[0045] According to one embodiment of the present invention, the composition is characterized in that a is a number in the range of 0.4 ≤ a ≤ 1.6, preferably in the range of 0.6 ≤ a ≤ 1.4.

[0046] Although we do not wish to be constrained by theory, the observed effect of the composition according to the present invention on the braking performance may be due to the presence of at least two different crystalline mixed phases of Fe, Zn, and S in the composition. These crystalline mixed phases may have a composition different from that of the overall composition.

[0047] Two compositions of formula I having different mixed crystalline phases of Fe, Zn, and S have never been described before.

[0048] It was found that the presence of two or more mixed crystalline phases of Fe, Zn, and S contributes to the effect of the composition according to the present invention.

[0049] The presence of such a crystalline mixed phase can be confirmed by XRD (X-ray diffraction) measurement. XRD measurement is performed using CuK α The measurements were performed using a PANalytical X'Pert PRO powder diffractometer equipped with linear and proportional counters.

[0050] The assignment of different phases can be determined from the X-ray diffraction patterns using database search routines (such as the PanICSD database) and Rietveld analysis. Rietveld analysis is well known in the art and is commonly used to refine the crystalline structure of minerals in powder form, allowing not only the differentiation of phases with overlapping XRD peaks but also the determination of the (weight) ratio of all phases.

[0051] Preferably, the composition of the present invention contains at least 30% by weight, preferably at least 50% by weight, and preferably at least 70% by weight of at least two different mixed crystalline phases of Fe, Zn, and S.

[0052] In a preferred embodiment, the composition contains a hexagonal phase and a cubic phase in the crystalline phase. The crystalline phase of the main body of the present invention and the weight ratio of the hexagonal phase to the cubic phase in the crystalline phase can also be determined by XRD measurement and subsequent Rietveld analysis.

[0053] Preferably, the composition used according to the present invention is characterized by containing both a cubic crystal phase of Fe, Zn, and S and a hexagonal crystal phase of Fe, Zn, and S.

[0054] Phases can be characterized by different stoichiometries and different arrangements of molecules in the solid.

[0055] An example of the cubic crystal phase of Fe, Zn, and S is sphalerite, in which Fe is incorporated (Fe-rich sphalerite). These sphalerites can have different formulas, for example, Fe 0.34 Zn 0.66 S or Fe 0.372 Zn 0.628 S. An example of the hexagonal crystal phase of Fe, Zn, and S is the hexagonal crystal phase of the formula Fe 0.33 Zn 0.67 S.

[0056] [[ID=]] In another preferred embodiment of the present invention, the composition according to the present invention further contains at least one additional crystal phase selected from the group consisting of iron sulfides and mixtures thereof.

[0057] The at least one additional crystal phase can ultimately become the overall composition of Formula I.

[0058] The iron sulfide phase can be, for example, of the formula FeS such as the crystal phase of troilite.

[0059] Furthermore, the iron sulfide phase can be a composition of Formula II Fe x S y II (where x is a number within the range of 0.8 ≤ x ≤ 3, preferably within the range of 1 ≤ x ≤ 3, and y is a number within the range of 1 ≤ y ≤ 4).

[0060] Preferably, the iron sulfide phase of the present invention is troilite. Troilite is an iron sulfide mineral having the formula of FeS that exhibits good thermal conductivity. [[ID=]]

[0061] The composition according to the present invention may further contain amorphous phases of Fe, Zn, and S, which can ultimately form the overall composition of formula I.

[0062] According to another preferred embodiment of the present invention, the compositions of the present invention are as follows: Fe 1.4 Zn 0.6 S2 Fe 1.05 Zn 0.95 S2 Fe 0.64 Zn 1.36 S2, Having or a mixture of one or more of the above compositions. It is characterized by the following.

[0063] To further reduce friction and wear, additives can be added to the composition according to the present invention. Additives can be particularly important in boundary lubrication regions, where they can prevent direct contact between solid surfaces and significantly reduce friction and wear. Several classes of additives exist, the main examples being organic friction modifiers, oil-soluble additives, functionalized polymers, and dispersed nanoparticles.

[0064] Another aspect of the present invention relates to the use of the compositions described herein as lubricants.

[0065] In this embodiment of the present invention, the composition may be present with one or more additives selected from the group consisting of fluorides such as CaF2, MgO, and CaSO3.

[0066] According to another embodiment of this aspect of the present invention, the composition according to the present invention is present together with one or more other lubricants such as a phosphate such as tricalcium phosphate (TCP), graphite or other metal sulfides.

[0067] Preferably, one or more additives or lubricants can be added to the composition after its synthesis.

[0068] The composition of the present invention is particularly useful as a lubricant in friction linings, preferably in brake linings and / or clutch linings.

[0069] Preferably, the composition of the present invention is a solid lubricant.

[0070] For example, the compositions of the present invention can be used in automobiles. These include engine components such as constant velocity joints, wheel bearings, and clutches, as well as various other components such as electric power steering, ball joints, door hinges, steering wheel parts, and cooling fans. Furthermore, the compositions of the present invention can also be used, for example, as lubricants for plastic compartments within automobiles.

[0071] A method for producing the composition defined above or a composition used as defined above is: - A step of mixing Fe, Zn, and S in elemental forms in a desired ratio to obtain a mixture of formula I, and - A step of thermally synthesizing the above mixture under vacuum. Includes.

[0072] The raw materials and / or the resulting mixture may optionally be milled or ground before the mixture is thermally synthesized.

[0073] The “thermogenesis” as used herein is carried out in a vacuum and oxygen-free environment for the preparation of the compositions according to the present invention, similar to the thermosynthesis pathway described in Piontek et al. ACS Catalysis, 2018, 8, 987-996.

[0074] In detail, the composition of the present invention is a) A step of preparing a homogeneous mixture of Fe powder, Zn powder, and S powder by mixing or grinding. The average particle size of the final mixture is preferably less than 100 μm. b) A step of transferring the mixture obtained in step a) to a sealed container under vacuum, wherein the vacuum is from 30 mbar to 10 -15mbar, preferably 1 mbar to 10 mbar -7 A process adjusted to the range of mbar. c) Heating a sealed container to a temperature range of 400 to 1500°C and holding it under two temperature lamps for 1 to 120 hours, preferably 700°C to 1200°C for 3 to 15 hours, more preferably 600°C to 800°C for 1 to 10 hours and 900°C to 1100°C for 1 to 20 hours. It can be manufactured containing [the specified ingredient].

[0075] The term "average particle size" as used herein is determined from the particle size distribution. 50 Refers to a value. d 50 The value is known as the median diameter or median of the particle size distribution and is expressed based on volume (dv). 50 ) or a display based on the number (dn 50 ) is determined from. In this application, d 50 The value is expressed based on volume, i.e., the particle diameter at 50% by volume in the cumulative distribution (e.g., d of 100 μm). 50 This refers to the fact that 50% by volume of particles have a diameter smaller than 100 μm.

[0076] Preferably, the particle size distribution is determined using laser diffraction particle analysis, preferably using a "Microtrac" particle analyzer such as a Microtrac S3500 or Microtrac X100 instrument, utilizing Fraunhofer analysis mode (measurement mode: full-range analysis of absorbing particles (FRA)).

[0077] Other instruments exhibiting comparable sensitivity and measurement range to the Microtrac S3500 or Microtrac X100, particularly comparable sensitivity in the lower limit and low-size region of detectable particle size, may be used to determine particle size distribution according to the present invention. Those skilled in the art will know of suitable commercially available instruments.

[0078] The mixtures described herein have a desired average particle size (d 50 It can be ground until ) is obtained.

[0079] The composition of the present invention can also be used in a method of lubricating a substrate, such as a friction lining, by bringing the composition of the present invention into contact with the friction material of the substrate, such as a friction lining.

[0080] The base material, such as friction material, can be a metal, ceramic, or organic material, and is generally known in the art.

[0081] The present invention will be described in more detail in the following examples and comparative examples, but will not be limited thereto. [Examples]

[0082] Iron powder (0.89g, Sigma-Aldrich, ≥99%), zinc powder (0.40g, Sigma-Aldrich, ≥99%), and sulfur (0.71g, Sigma-Aldrich, 99.5%~100.5%), each having an average particle size of less than 100 μm, were mixed together until a homogeneous aggregate of the elements was obtained. The homogeneous elemental mixture was filled into quartz ampoules (10 mm diameter, total volume: 15 mL), and then 4 × 10⁻⁶ -2 The sample was evacuated to a pressure of less than mbar for 16 hours, then sealed under vacuum. The sample was placed in an oven and heated for 4.5K. -1 The mixture was heated to 700°C at the following heating rate. After maintaining the temperature isotherm for 3 hours to allow the sulfur to react with the metal mixture without damaging the container, the temperature was raised to 1000°C (3.33K min). -1 The heating rate was increased to enhance diffusion. The sample was then kept at this temperature for 10 hours. After that, the sample was allowed to cool to room temperature. The molar ratios of Fe, Zn, and S in the resulting composition are disclosed in Table 1. [Examples]

[0083] Iron powder (0.63 g, Sigma-Aldrich, ≥99%), zinc powder (0.67 g, Sigma-Aldrich, ≥99%), and sulfur (0.69 g, Sigma-Aldrich, 99.5%~100.5%) were mixed together until a homogeneous aggregate of the elements was obtained. The composition was obtained by the same method as described in Example 1. The molar ratios of Fe, Zn, and S in the resulting composition are disclosed in Table 1. [Examples]

[0084] Iron powder (0.38 g, Sigma-Aldrich, ≥99%), zinc powder (0.94 g, Sigma-Aldrich, ≥99%), and sulfur (0.68 g, Sigma-Aldrich, 99.5%~100.5%) were mixed together until a homogeneous aggregate of the elements was obtained. The composition was obtained by the same method as described in Example 1. The molar ratios of Fe, Zn, and S in the resulting composition are disclosed in Table 1. [Examples]

[0085] 1.8g Fe 1.4 Zn 0.6 S2 (prepared according to Example 1) and 0.2 g of graphite (SBL / Kaiserberg) were mixed together until a homogeneous aggregate of the material was obtained. [Examples]

[0086] 1.8g Fe 1.4 Zn 0.6 S2 (prepared according to Example 1) and 0.2 g of tricalcium phosphate (TCP; Chemische Fabrik Budenheim KG) were mixed together until a homogeneous aggregate of the material was obtained.

[0087] Comparative Example 1 The performance of the suspension of the present invention was compared using commercially available solid lubricants containing pure SnS.

[0088] Comparative Example 2 The performance of the suspension of the present invention was compared using a commercially available solid lubricant containing pure FeS.

[0089] Comparative Example 3 The performance of the suspension of the present invention was compared using a commercially available solid lubricant containing pure ZnS.

[0090] Comparative Example 4 1.4 g of the powder from Comparative Example 2 and 0.6 g of the powder from Comparative Example 3 were mixed together until a homogeneous aggregate of the material was obtained.

[0091] Comparative Example 5 Fe 0.6 Zn 0.22 Bi 0.12 The performance of the suspension of the present invention was compared using a commercially available solid lubricant containing S and no further components ("Tribotecc SLX 121").

[0092] [Table 1]

[0093] Test conditions The examples and comparative examples were incorporated into a common NAO formulation (see Tables 2 and 3), and brake pads of the same dimensions, similar to commercially available brake pads, were pressed (see Table 4). A press of Manufacturer: IAG LCM-1-090D was used with 140g of the final formulation at a temperature of 150°C, with a pressure of 3.0 kN / cm². 2 It was used with a pressing force of 44 bar, a hydraulic pressure of 44 bar, and a contact pressure of 132.51 kN.

[0094] [Table 2]

[0095] [Table 3]

[0096] The formulation was processed in a series of pressing and ventilation steps according to Table 4 below:

[0097] [Table 4]

[0098] The pressed pads were cured in a muffle furnace at a heating rate of 0.73 K / min from 25°C to 200°C and held at 200°C for 4 hours. The cured pads were then crushed to a thickness of 0.3 mm. Cast iron discs (ATE 240122-0210.1) were used as the discs. The application properties of the pads were investigated using the AK-Master test (SAE J2522) and block wear tests.

[0099] AK-Master Exam: The AK-Master test was conducted in accordance with SAE J2522, with a target weight of 64.92 kgm. 2 The test was conducted using a Link 2800 dynamometer, and the technical data is shown in Table 5.

[0100] [Table 5]

[0101] Block wear test: The block wear test was performed on a Link 2800M dynamometer, yielding 64.92 kgm. 2 The test was conducted using inertia, with a brake pressure of 20 bar, 100 stops from 80 km / h to 5 km / h at 100°C, followed by 300 stops from 100 km / h to 50 km / h at 0.51 G at each temperature (100°C, 200°C, 300°C, 400°C, 500°C).

[0102] Characterization of the composition The composition according to the present invention was characterized by XRD. Powder diffraction experiments were performed using CuK αThe measurements were performed using a PANalytical X'Pert PRO powder diffractometer equipped with linear and proportional counters. All measurements were performed in a reflection configuration. A PANalytical backloading system was used for sample preparation. Powder diffraction measurements were controlled and handled by the Highscore Plus program suite. Phase analysis was performed using a search routine called the PanICSD database. Furthermore, Rietveld analysis was performed using the HighScore Plus 4.1 software.

[0103] Measurement parameters: Incident beam path: 0.04 radian solar slit 15mm Fixed Incident Beam Mask Programmable Divergent Slit Diffraction beam path: 0.04 radian solar slit Monochromemeter Programmable light-receiving slit (0.30 mm height) Fixed 2° scattering prevention slit Xe proportional detector measurement: 10 - 80°2θ 0.04° step 5 seconds counting time per step

[0104] result AK-Master Exam:

[0105] [Table 6]

[0106] It should be noted that higher values ​​for CoF and fade, and lower values ​​for pad wear and disc wear are preferred, indicating reduced material wear.

[0107] The results in Table 6 show that the compositions according to the present invention (Examples 1 to 5) in Fade Block 2 are equivalent to tin sulfide (Comparative Example 1). Even more surprisingly, the compositions according to the present invention showed significantly reduced pad wear and disc wear compared to tin sulfide. This is particularly advantageous because tin-based lubricants are far more expensive than the raw materials for the compositions of the present invention.

[0108] The results also show that pure iron sulfide (Comparative Example 2) and zinc sulfide (Comparative Example 3) were less effective in terms of fade 2 than the examples related to the present invention. Furthermore, the composition according to Comparative Example 4 had a similar atomic ratio to the composition of Example 1, but showed reduced performance in terms of fade 2 and pad wear compared to the composition according to the present invention.

[0109] Surprisingly, the composition of the present invention demonstrated these advantages compared to Comparative Example 5, which is shown by higher pad wear and slightly reduced disc wear.

[0110] Furthermore, the AK-Master test revealed that the composition of the present invention according to Example 1 exhibited better behavior in fade block 2 and better stability of CoF in each test block compared to Comparative Examples 1 to 5 (see Figures 1a, 2a, 3a, 4a, and 5a).

[0111] In addition to the simplified results of the AK-Master test, further detailed results of pad wear and disc wear for each of Comparative Examples 1 to 5, as discussed herein, are depicted in Figures 1b, 1c, 2b, 2c, 3b, 3c, 4b, 4c, 5b, and 5c.

[0112] Figures 1a, 2a, 3a, 4a, and 5a show some of the more measurement points in the AK-Master test in a simplified manner.

[0113] These measurement points are indicated by numbers in the diagram. The test conditions for each of these points are as follows: 1:30 bar, 80-30 km / h, operating μ, characteristic value 3 2:10-80 bar, 120-80 km / h, speed, pressure, characteristic value 4.3 3:10-80 bar, 170-150 km / h, speed, pressure, characteristic value 4.5. 4.30 bar, 80-30 km / h, operating μ, characteristic value 5 5: 40℃, cold application, characteristic value 6 6: 160-90km / h, 100-5km / h, highway, characteristic value 7 7:30 bar, 80-30 km / h, driving μ, characteristic value 8 Braking from 8:100km / h to <5km / h, fade 1, characteristic value 9 9:30 bar, 80-30 km / h, driving μ, characteristic value 10 10: 500℃, 80-30km / h, temperature / pressure, characteristic value 12 11:80-30km / h, driving μ, characteristic value 13. 12: Braking from 100 km / h to <5 km / h, fade 2, characteristic value 14. 13:80-30km / h, driving μ, characteristic value 15.

[0114] Furthermore, the AK-Master test revealed that the composition according to the present invention (Example 1) exhibited significantly lower pad wear of up to 17% compared to the compositions of Comparative Examples 1, 3, 4, and 5 (see Figures 1b, 3b, 4b, and 5b). Only the composition of Comparative Example 2 showed comparable results in terms of pad wear (see Figure 2b).

[0115] Regarding disc wear, the composition of Example 1 showed significantly lower wear (up to 38%) than the compositions of Comparative Examples 1, 2, and 5 (see Figures 1c, 2c, and 5c) and comparable results to Comparative Examples 3 and 4 (see Figures 3c and 4c).

[0116] In summary, these results demonstrate superior braking performance compared to compositions using the latest technology materials.

[0117] XRD measurement: The difference between the composition of the present invention and Comparative Example 5 lies in the presence of at least two different mixed crystalline phases between zinc, iron, and sulfur. The presence of such phases is considered to be the reason for the superior performance of the composition of the present invention compared to other compositions known in the art. Examples 1, 2, and 3 each contain two different mixed crystalline phases.

[0118] In detail, XRD measurements confirmed that the composition of the present invention contains mixed crystalline phases of Fe and S, and Fe, Zn, and S, as shown in Table 7, in contrast to other metal sulfides such as the composition of Comparative Example 5.

[0119] [Table 7]

[0120] The XRD spectra of Examples 1, 2, and 3 and Comparative Example 5 are shown in Figures 6, 8, 10, and 12.

[0121] Figures 7, 9, 11, and 13 show the characteristic peaks of the Fe-S and Fe-Zn-S crystalline phases predicted from the XRD database for each example. Each crystalline phase is indicated in the figures by the numbers summarized in Tables 8 to 11.

[0122] Table 8 shows the crystalline phase compared to Example 1 shown in Figure 7.

[0123] [Table 8]

[0124] Table 9 shows the crystalline phase compared to Example 2 shown in Figure 9.

[0125] [Table 9]

[0126] Table 10 shows the crystalline phase compared to Example 3 shown in Figure 11.

[0127] [Table 10]

[0128] Table 11 shows the crystalline phase compared to Comparative Example 5 shown in Figure 13.

[0129] [Table 11]

[0130] Figures 7, 9, and 11 show that many of the peaks in the patterns of Examples 1, 2, and 3 (Figures 6, 8, and 10) correspond to the known cubic and hexagonal phases of mixed FeZnS crystals (Fe 0.34 S1Zn 0.66 Or Fe 0.372 S1Zn 0.628 Cubic Fe-sphalerite and hexagonal Fe 0.33 S1Zn 0.67 ).

[0131] Fe 0.372 Zn 0.628 Regarding the cubic sphalerite phase of form S (Figure 9, no. 8; Figure 11, no. 4), a peak typical of this phase can be detected at position 69 (*2θ) in both Examples 2 and 3.

[0132] In contrast, Figures 12 and 13 show that the composition of Comparative Example 5 does not exhibit peaks that would correspond to the mixed crystalline phase.

[0133] Block wear test: In block wear tests, the advantages of the composition of the present invention compared to state-of-the-art materials can be demonstrated.

[0134] Figure 14a shows that the average CoF (μ) of Example 1 is within the same range as Comparative Example 1 at temperatures up to 300°C. Above 400°C, the CoF of the pads with the composition of Example 1 increases more than that of Comparative Example 1.

[0135] Figure 14b shows a clear difference in pad wear. Up to 200°C, the wear of both materials is at a similar level. However, above 300°C, the composition according to Example 1 shows a significant advantage over Comparative Example 1. A 33% reduction in pad wear was observed throughout the entire test.

[0136] Within the disc wear range, the curves remain very similar up to 200°C, as shown in Figure 14c. While tin sulfide wear increases significantly from 400°C, the wear of the composition according to Example 1 is significantly lower. Over the entire cycle, disc wear was reduced by 64%.

[0137] Comparative Example 6 To demonstrate the advantages of having two ternary crystalline phases, further tests were conducted to compare Example 1 of the present invention with a composition containing one crystalline phase of Fe, Zn, and S.

[0138] To do this, the powder from Example 1 was further heated to 700°C and the temperature was maintained for 1 hour to obtain the powder according to Comparative Example 6.

[0139] XRD-measurement: The composition according to Comparative Example 6 was characterized by XRD as described above.

[0140] The results in Table 12 show that the heat treatment of the powder in Example 1 resulted in the removal (<1 wt%) of the FeZnS hexagonal phase in Comparative Example 6. XRD measurements revealed that, in contrast to Example 1, which contains two different mixed crystalline phases of Fe, Zn, and S (Fe-sphalerite cubic + FeZnS hexagonal), the powder in Comparative Example 6 contains only one crystalline phase of Fe, Zn, and S (Fe-sphalerite cubic).

[0141] [Table 12]

[0142] Test conditions For the AK-Master test, the powder of Comparative Example 6 was incorporated into the NAO formulation at a ratio of 6% by weight, equivalent to that of the formulation, as described above in Table 2.

[0143] For block wear testing, an NAO formulation equivalent to the above-mentioned formulation in Table 2 was prepared, containing 4% by weight of the powder of Comparative Example 6.

[0144] The formulations were pressed under the same conditions as described above.

[0145] The applicability of the pads was investigated using the AK-Master test (SAE J2522) and block wear test, as described above.

[0146] result AK-Master Exam: Although the results of the simplified AK-Master tests for Example 1 and Comparative Example 6 were similar, the composition of Example 1 showed significantly lower pad and disc wear (up to 12%) than the composition of Comparative Example 6, as shown in Figures 15a and 15b.

[0147] These results demonstrate the superior braking performance of the composition according to the present invention compared to Comparative Example 6.

[0148] Block wear test: The advantages of the composition of the present invention compared to Comparative Example 6 were confirmed in the block wear test.

[0149] Table 13 shows the clear difference in pad wear between the composition of Example 1 and Comparative Example 6. An overall reduction of 9% in pad wear was observed throughout the entire test. These results demonstrate that an increase in pad wear performance can be achieved with Example 1 according to the present invention. The disc wear of Example 1 and Comparative Example 6 was comparable.

[0150] [Table 13]

Claims

1. Equation I Fe ２－ａ Zn ａ S ｂ I (In the formula, a is a number in the range of 0.2 ≤ a ≤ 1.8, b is a number in the range of 1.8 ≤ b ≤ 2.2, preferably in the range of 1.9 ≤ b ≤ 2.1, and most preferably b = 2. (where a represents the molar ratio of Zn in the overall composition, and b represents the molar ratio of S in the overall composition) A composition containing at least two different mixed crystalline phases of Fe, Zn, and S, as determined in accordance with this specification.

2. The composition according to claim 1, characterized in that a is a number in the range of 0.4 ≤ a ≤ 1.6, preferably in the range of 0.6 ≤ a ≤ 1.

4.

3. The composition according to claim 1 or 2, characterized by containing at least 30% by weight, preferably at least 50% by weight, and preferably at least 70% by weight, of at least two different mixed crystalline phases of Fe, Zn, and S.

4. The composition according to any one of claims 1 to 3, characterized in that it contains both a cubic crystalline phase of Fe, Zn, and S and a hexagonal crystalline phase of Fe, Zn, and S, as determined in accordance with this specification.

5. The composition according to any one of claims 1 to 4, further comprising at least one further crystalline phase selected from the group consisting of iron sulfides and mixtures thereof, as determined in accordance with this specification.

6. The following compositions: Fe １．４ Zn ０．６ S ２ Fe １．０５ Zn ０．９５ S ２ Fe ０．６４ Zn １．３６ S ２ 、 Having or a mixture of one or more of the above compositions. The composition according to any one of claims 1 to 5, characterized by...

7. Use of the composition according to any one of claims 1 to 6 as a lubricant.

8. The composition is CaF ２ Fluorides such as MgO and CaSO4 ３ The use of the composition according to claim 7, characterized in that it is present together with one or more additives selected from the group consisting of the following.

9. The use of the composition according to claim 7 or 8, characterized in that the composition is present together with one or more other lubricants such as tricalcium phosphate (TCP) or other phosphates, graphite, and metal sulfides.

10. A method for producing the composition according to any one of claims 1 to 6. - A step of mixing Fe, Zn, and S in elemental forms in a desired ratio to obtain a mixture of formula I, and - A step of thermally synthesizing the above mixture under vacuum. A method that includes this.

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