Aluminium - tourmaline metal matrix composite material

Abstract

The invention relates to obtaining a metal matrix composite material having a vibration damping capability higher than aluminium by keeping the density of the material as constant as possible and by improving / keeping at a possible level the mechanical properties, specifically for aluminium-based materials.

Description

[0001] ALUMINIUM - TOURMALINE METAL MATRIX COMPOSITE MATERIAL Technical Field of the Invention

[0002] The invention relates to an aluminium-tourmaline metal matrix composite material having improved vibration damping, increased modulus of elasticity, and enhanced machinability. Primarily for use in the automotive and aerospace sectors, a composite material is obtained together with a low-cost tourmaline mineral reinforcement material in order to increase or bring to a desired level mechanical properties such as lightness, vibration damping, and strength of various structures.

[0003] State of the Art

[0004] Metal matrix composite (MMC) materials are composite materials formed by distributing various reinforcement materials within a metal matrix. Metal matrix composites provide superior properties for engineering applications by further increasing the strength, hardness, and mechanical resistance of the metal forming the matrix through the contributions of the reinforcement materials. MMCs are particularly preferred in applications requiring properties such as high temperature resistance, wear resistance, and strength.

[0005] Metal matrix composite materials may be produced by various methods. Common production methods include liquid metal processes, solid-state processes, and chemical vapour deposition. In liquid metal processes, the metal matrix is melted and the reinforcement materials are added to this liquid matrix. During this process, stirring is carried out to ensure homogeneous distribution. In solid-state processes, metal powders and reinforcement materials are mixed and sintered. In the chemical vapour deposition method, the metal is vapourised and condensed on a surface, and reinforcement materials are deposited on this surface.

[0006] The properties of MMCs vary depending on the type of metal matrix and reinforcement materials used. In general, MMCs have superior properties such as high strength, low density, high temperature resistance, good wear resistance, and increased thermalconductivity. These properties make MMCs attractive in various industries such as aerospace, automotive, defence, and sports equipment.

[0007] Among the most popular examples of MMCs are composites in which light metals such as aluminium, magnesium, and titanium are used as the matrix. Reinforcement materials generally include carbon fibres, ceramic particles (for example, silicon carbide and alumina), and boron fibres. Aluminium metal matrix composites (AI-MMCs) particularly stand out due to their combination of lightness and strength and are widely used.

[0008] In the production of aluminium metal matrix composite materials, the reinforcement materials commonly used are known as silicon carbide and boron carbide. Although silicon carbide can improve the mechanical properties of the structure, it can significantly embrittle the structure [1], The use of silicon carbide also imparts abrasiveness to the material [2], This situation negatively affects the machinability of the material. Both situations are also observed for boron carbide [3], In addition to all these, the cost of both materials is quite high.

[0009] Due to the limitations and inadequacies of the solutions in the current state of the art, such as embrittlement of the aluminium composite material obtained with the used reinforcement elements, increased abrasiveness, reduced machinability, and the high cost of reinforcement elements, it has become necessary to make an improvement in the field of aluminium metal matrix composites.

[0010] Brief Description and Aims of the Invention

[0011] The invention describes an aluminium metal matrix composite (MMC) material containing tourmaline mineral particles as a reinforcement material. The MMCs in question have improved vibration damping and machinability, and can be produced at low cost due to the inorganic natural mineral particles used.

[0012] An aim of the invention is to obtain an aluminium MMC material having improved vibration damping, increased modulus of elasticity, and enhanced machinability. For this purpose, tourmaline particles are homogeneously distributed within the aluminium matrix by benefiting from the piezoelectric and mechanical properties of the tourmaline mineral. This targeted composite material both increases vibration damping capacityand improves machinability, thereby offering an ideal solution especially for automotive, aerospace, and high-precision engineering applications.

[0013] Another aim of the invention is to minimise the increase in the density of the obtained MMC in order to facilitate its use in the automotive and aerospace sectors. For this reason, the proportion of the tourmaline mineral, which has a higher density compared to aluminium (2820-3320 kg / m3), is kept at a low level.

[0014] In addition, another aim of the invention is to obtain a low-cost aluminium MMC material. Since tourmaline is a natural mineral and can be supplied directly, it provides a significant cost advantage. This economic advantage not only requires less expenditure in the aluminium MMC production process, but also supports a sustainable and environmentally friendly approach.

[0015] Detailed Description of the Invention

[0016] The invention relates to an aluminium-tourmaline metal matrix composite (MMC) in order to improve vibration damping and machinability. The MMC in question contains tourmaline with a particle size of 70-80 pm at a mass fraction of 1-5%. In this way, mechanical properties are improved while keeping the density of the material at a level of 270-2730 kg / m3, and the use of the MMC in the automotive and aerospace sectors is facilitated.

[0017] In one embodiment of the invention, an aluminium-tourmaline metal matrix composite in order to improve vibration damping and machinability contains 5% by mass tourmaline and 95% aluminium.

[0018] In one embodiment of the invention, the tourmaline mineral contained in an aluminium-tourmaline metal matrix composite in order to improve vibration damping and machinability has a particle size of 75 pm.

[0019] As a production method, a stir casting technique is used in order to ensure homogenisation. Following this process, the material is subjected to T6 heat treatment. The artificial ageing stage, which is one of the T6 heat treatment steps, significantly improves the vibration damping capability of the material.Inorganic natural mineral particles attract great interest as potential reinforcement materials due to their low cost and ease of production. Compared to commonly used silicon carbide and boron carbide materials, the tourmaline mineral used as the reinforcement material in the developed composite material provides a significant cost advantage due to being a natural mineral and its direct availability.

[0020] According to the results of the tensile test carried out in accordance with DIN EN ISO 6892-1 on the produced composite material, the average yield strength was obtained as 180.50 MPa, tensile strength as 251.00 MPa, modulus of elasticity as 76.19 GPa, and elongation as 6.34%. In addition, free vibration analysis was carried out on plates produced from said composite by the impact hammer method. The vibration damping ratio of said MMC was calculated to be 50% higher than that of the aluminium (A356) matrix material by performing an impact hammer free vibration test on a 250x250x8 mm plate. The mechanical properties of the aluminium-tourmaline metal matrix composite material are given in Table 1.

[0021] Table 1. Mechanical Properties of Aluminium-Tourmaline Metal Matrix Composite Material

[0022] Yield

[0023] Reinforcement Ratio Tensile Modulus of Elongation Stress

[0024] (Mass) Stress (MPa) Elasticity (GPa) (%)

[0025] (MPa)

[0026] 1-5% 180.50 251.00 76.19 6.34

[0027]

[0028] Tourmaline is a material belonging to a silicate group called cyclosilicates (ring silicates), which form compounds with many elements, having a polar crystalline structure, formed as a result of inorganic natural processes, and inherently exhibiting hydrophilic properties. Its general physical properties are as follows:

[0029] • Crystal System: Trigonal.

[0030] • Crystal Form: Prismatic; prism surfaces longitudinally striated; parallel or radial crystal groups common; sometimes massive-compact structure.

[0031] • Hardness (according to MOHS): 7-7.5.• Specific Gravity: 3.0-3.2.

[0032] • Lustre: Vitreous, resinous.

[0033] • Colour: Black variety schorl (Fe), brown dravite (Mg). In addition, it may be yellow, pink, blue, or colourless.

[0034] • One of the most important physical properties of tourmaline is that it has “pyroelectricity” (except for the iron-rich tourmaline type “schorl”). This property is expressed as one end of the tourmaline crystal becoming positively charged and the other end negatively charged when heated up to 100°C. A tourmaline crystal heated in this way gains the ability to attract dust.

[0035] • Another important physical property observed in tourmalines is “piezoelectricity”. Piezoelectricity is the formation of electrical charge as a result of applying directional pressure to the crystal (along the vertical axis). For example, this important property has enabled the use of low-iron tourmaline crystals in devices used for detecting and measuring underwater explosion pressures in submarine vehicles and in the manufacture of depth recording devices. Tourmaline-based piezoelectric pressure sensors have continued to be used and developed for applications related to shock waves, explosions, and explosion detection (including atomic explosions) in environments up to 700°C. Tourmaline has a crystallographic structure capable of accommodating a wide range of cations.

[0036] The general formula of tourmaline is XY3Z6Si6Oi8(BO3)3W4, and the accepted and possible end members are distinguished according to the X, Y, and Z cations. X = Na+, Ca2+, K+; Y = Mg2+, Fe2+, Mn2+, Al3+, Fe3+, Cr3+, Mn4+, Li+; Z = Al3+, Mg2+, Fe3+, Cr3+, V3+; w = o2-, OH-, F-, or.

[0037] The production method of an aluminium-tourmaline metal matrix composite in order to improve vibration damping and machinability is as follows;

[0038] a. Powdering the tourmaline mineral to a particle size of 70-80 pm by coarse, fine, and precision grinding methods

[0039] b. Subjecting the powdered tourmaline at a mass fraction of 1-5% to preheating at 750°C for 30 minutes

[0040] c. Melting A356 aluminium at a mass fraction of 95-99% at 750°C in an electric melting furnaced. Creating a vortex in the molten aluminium and adding the heated powdered tourmaline at a mass fraction of 1-5% into the crucible

[0041] e. Stirring the aluminium-tourmaline mixture in the crucible for 4 minutes at 420 RPM (7 Hz)

[0042] f. Removing the mixture cast into the mould from the mould and subjecting it to T6 heat treatmentReferences

[0043] [1] Sujan, D., Yeo, C. W., Rahman, M. E., Reddy, M. M., Maleque, M. A., & Mohammad, Y. A. (2012a). Aluminium-silicon carbide composites for enhanced physio-mechanical properties. Advanced Materials Research, 576, 370-373.

[0044] [2] Singla, M., Singh, L., & Chawla, V. (2009). Study of wear properties of Al-SiC composites. Journal of Minerals and Materials Characterization and Engineering, 08(10), 813-821.

[0045] [3] Brillon, A., Garcia, J., Riallant, F., Garnier, C., Joulain, A., Lu, Y., & Silvain, J.-F. (2022). Characterisation of AI / B4C composite materials fabricated by powder metallurgy process technique for nuclear applications. Journal of Nuclear Materials, 565, 153724.

Claims

CLAIMS1. An aluminium-tourmaline metal matrix composite in order to improve vibration damping and machinability, comprising 1-5% by mass tourmaline and 95-99% aluminium.

2. The aluminium-tourmaline metal matrix composite according to claim 1, comprising 5% by mass tourmaline and 95% aluminium.

3. The aluminium-tourmaline metal matrix composite according to claim 1, wherein the particle size of the tourmaline mineral contained therein is 70-80 pm.

4. The aluminium-tourmaline metal matrix composite according to claim 1, wherein the particle size of the tourmaline mineral contained therein is 75 pm.

5. A production method of an aluminium-tourmaline metal matrix composite according to claim 1 , comprising the process steps of;a. powdering the tourmaline mineral to a particle size of 70-80 pm by coarse, fine, and precision grinding methods,b. subjecting the powdered tourmaline at a mass fraction of 1-5% to preheating at 750°C for 30 minutes,c. melting A356 aluminium at a mass fraction of 95-99% at 750°C in an electric melting furnace,d. creating a vortex in the molten aluminium and adding the heated powdered tourmaline at a mass fraction of 1-5% into the crucible, e. stirring the aluminium-tourmaline mixture in the crucible for 4 minutes at 420 RPM (7 Hz), andf. removing the mixture cast into the mould from the mould and subjecting it to T6 heat treatment.

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