oz metalurjisi imalat yöntemi ile alüminyum matrisli TiC takviyeli kompozit malzeme üretimi ve çekme mukavemeti testlerinin analizi = Production of aluminum matrix TiC reinforced composite material by powder metallurgy manufacturing method and analysis of tensile strength tests

Abstract

Powder metallurgy (P/M) is a manufacturing technique that consists of the analysis of techniques such as powder metals, particle reinforced composites, ceramics, forging, and molding, and in which materials are produced by mixing metal powders with appropriate standards and specific values and sintering them under controlled atmospheric conditions. In other words, it is a method of producing parts by bringing metals into fine powder form, mixing them in a certain ratio, pressing them in precise molds at room temperature at pressures appropriate to predetermined technical values, and then sintering them under controlled atmospheric conditions. This method consists of various stages such as powder production, blending the obtained powders, compacting the powders, sintering and optional additional processes (infiltration, oil impregnation, deburring, etc.). This technique minimizes material waste and provides high precision and efficiency. In this method, powders that do not dissolve in each other are mixed using appropriate reinforcement materials, cold pressing and then sintering are performed to obtain the desired properties. Composite materials constitute a category of advanced technological materials. These materials are the first materials developed by humanity to protect itself from external factors and have begun to enter almost every area of our lives in this century, and their areas of use are also rapidly expanding. Parts produced with the P/M manufacturing method have many areas of use in the sector. These include various applications such as aircraft brake pads, high-power lights, electrical contact elements, bearings, armor-piercing bullets, automobile transmission shafts, orthopedic prostheses, nuclear fuel rods, rechargeable batteries, high-temperature filters, electronic capacitors, watch cases and jet engine turbines. In addition, this production method has many advantages such as low investment costs, flexibility of the equipment used, high efficiency and easy production of materials with different properties. The mechanical alloying technique is a powder processing method used to improve solid state reactions and material properties. This method is usually carried out by grinding micron-sized metal powders in a high-energy mill. The mechanical alloying technique is used to mix a series of materials homogeneously and to form new, usually amorphous or nanocrystalline materials. During the mechanical alloying process, the sufficient force applied to the powders grinds the powders and bonds are formed between the formed powder particles at low temperature. The internal structure of the final powder is usually finer than the powders xxiv formed by atomization. The microstructure has particles of similar size formed by serial cooling methods. In addition, the powder particles are positioned between the balls. This causes elongation in the microstructure and increases the mechanical quality. Technically, the mechanical alloying method is generally a suitable technique for the production of metal matrix composite materials. The reason is that it allows to obtain specialty at a high level from the qualities handled with other techniques. This method is to ensure that the reinforcement material is spread homogeneously within the matrix by removing the agglomeration of the reinforcement particles. Furthermore, if there is a fault in the reinforcement material as a result of this continuous impact, it eliminates it and prevents the composite material from deforming suddenly. With the use of this method and these powders, not only the unprocessed states but also the problems that arise with different techniques are eliminated. Recently, aluminum matrix composites have been used in the automotive industry, especially in applications such as engine pistons, cylinder liners, brake discs and drums, thanks to their low cost, lightness, high strength, high elasticity modules and superior wear resistance. Ceramics, especially silicon, which is frequently encountered in the kitchen, and kardur, the favorite of chefs, are used to strengthen the mechanical properties of aluminum matrix composites. The main reinforcement materials used to strengthen the mechanical properties of aluminum matrix composite materials are ceramics such as TiC, SiC, B4C and Al2O3. Since our country has rich boron resources, B4C composite material stands out with its superior physical and chemical properties. Composite materials are increasingly attracting the attention of researchers due to their low cost, lightness, superior mechanical and thermal properties. Composite materials are classified as metal, ceramic and polymer matrix composites depending on the matrix material. Metal matrix composite materials consist of a matrix material consisting of reinforcement elements in particle form and a metal or alloy. Metals such as aluminum (Al), titanium (Ti), magnesium (Mg), copper (Cu) are generally preferred as matrix materials, and metal nitrides (Si3 N4 , TiN, TaN, ZrN etc.), metal carbides (SiC, B4 C, WC etc.) and metal oxides (Al2 O3 , SiO2 , ZrO2 etc.) are preferred as reinforcement elements. Aluminum is often preferred as the matrix material in MMK materials because it has an almost 100% recycling rate, is easily formed, is lightweight, and has good electrical and thermal conductivity. It is used extensively due to these properties. Nowadays, aluminum and its alloys are used in a number of sectors such as construction, aviation, aerospace and the automotive industry. In this study, Al matrix TiC reinforced composite materials were produced using the P/M manufacturing method. Powder mixtures were created by adding 0%, 1% and 5% TiC by weight to the Al7075 matrix material and 0.25% steric acid to each mixture. The resulting mixtures were mixed in a mechanical alloying test device for 1, 2, 5 and 10 hours. The obtained powder mixtures were produced by cold pressing at 450 Mpa pressure and sintered in a sintering furnace at 600 °C for 60 minutes. Then, the burrs on the parts were cleaned with roto finish process. Experiments were performed on the produced samples and their microstructures and tensile strength values were examined. xxv In the obtained samples, the distribution of matrix and reinforcement material powders in the chamber was observed homogeneously. As a result of the experiments; differences were observed in the main components of the composite materials depending on the added TiC and effects were observed in the tensile strength values. It was observed that the particles were more agglomerated as the TiC ratio in the matrix increased. Due to this grain size difference that occurred as a result of the reinforcement element (TiC) being in nano size and the powders forming the Al7075 matrix being in macro size, agglomerates were formed in the mixture and as a result, the porosity rate increased. The main reason for this was that sufficient surface bonding could not be provided between the Al7075 matrix material and the TiC reinforcement material as a result of agglomerations and porosities were observed at these points. It was concluded that mixing the mixture too much disrupted the structure of the powders. With the increase in the TiC reinforcement material ratio and due to the nano-sized nature of the material, the tensile strength increased for the 1% mixture. When the prepared composite materials were examined, it was observed that the tensile strength values increased up to 2 hours, and these values began to decrease after 2 hours. This means that mixing the mixture for more than 2 hours disrupted the structure of the powders and also reduced the tensile strength values. As a result; when the tensile strength test results of the milled composite materials were examined, it was determined that the highest strength value was in the 2-hour mixture sample with 1% TiC reinforcement.