Manufacturing of CK45 / RGO composite using recycled powder from machining waste

Abstract

Sustainable recycling approaches are an attractive and emerging topic for the environmental safety of manufacturing. The chips produced in machining have the potential to be reused for more sustainable and cost-effective production routes, such as powder production from chip mills for additive manufacturing. Recycling of useful materials such as steel with low processing costs, which combines economic and engineering advantages, is a critical demand for more sustainable design of reliable components for the aerospace and automotive industries. The present study uses CK45 steel for recycling and by generating machining chips in a closed cycle, it is possible to achieve the aforementioned rare combination of material properties. The produced composites containing 0.01 and 0.02 wt% reduced graphene oxide were fabricated by spark plasma sintering and were investigated for their properties by hardness, abrasion, scanning electron microscopy, and XRD. Hardness and abrasion tests have shown that this type of waste has a hardness suitable for use in component manufacturing in industries sensitive to hardness and abrasion. The numerical values ​​of the hardness and abrasion tests indicate an increase of 140 units in hardness and a decrease of 18 mg in the weight of the produced samples compared to the original cast sample, respectively.

Description

Description of the invention Title of the invention Fabrication of CK45 / RGO composite, using recycled powder from machining chips Technical background of the relevant invention C09 - C21 - C40 Technical problem and stating the objectives of the invention Industrial activity directly emitted 9.4 gigatonnes of carbon dioxide in 2021, a quarter of global emissions, with iron and steel production accounting for 30% of global CO2 emissions in 2021 [1]. This trend is accelerating as industrial emissions have increased by more than 70% since 2000, driven by rising global demand for industrial goods, coupled with modest increases in energy efficiency [1]. It is easy to predict that decoupling material demand from economic and population growth could help reduce CO2 emissions. One of the main pathways to reduce primary material production and decouple resource depletion from economic growth is to implement circular economy strategies including longer life, repair, product upgrading, modularity, remanufacturing, component reuse and recycling. Solid-state recycling strategies are one way to prevent damage to recycled manufacturing components. This method directly converts steel scrap into semi-finished products, avoiding the remelting step.Manufacturing in specific industrial environments presents many challenges, where raw material resources and energy consumption are two very important factors to consider. The ability to harvest metal scrap and reuse it as raw material can enable production when material availability is limited. The use of powders obtained from machining swarf has been tried and tested in the past[2]. Generally, swarfs produced by machining processes are considered as metal scraps and sent for melting, which completely eliminates their processing history. In a recent study, an iterative process approach was followed to fabricate cylinders by compacting conventional AISI-SAE H11 tool steel swarfs, which were previously converted into powders[3]. Effectively, metal swarfs can be the raw material for powder technologies such as additive manufacturing (AM)[4]. A description of the state of the prior art and the history of developments related to the claimed invention. In a study, Dong et al. fabricated a titanium-based composite reinforced with 0.6 wt% reduced graphene oxide (rGO) using spark plasma sintering (SPS) technology at different sintering temperatures from 800 to 1100 °C and investigated the effect of SPS temperature on microstructural changes and mechanical properties of Ti / rGO composites. The results showed that with increasing sintering temperature, the relative density and compactness of the composites improved. The optimal sintering temperature was 1000 °C for 5 min under a pressure of 45 MPa in vacuum. The sintered Ti / rGO composites obtained the best mechanical properties at a sintering temperature of 1000 °C and showed microhardness and tensile strength values ​​of 224 Vickers and 535 MPa, respectively. These results are much higher than those of the composites fabricated at 900 °C. One of the shortcomings of this study is the lack of reference to comparing the results of graphene-containing samples with pure samples and the results of bio-tests, which are discussed in the present study. L.L. Dong, B. Xiao, Y. Liu, Y.L. Li, Y.Q. Fu, Y.Q. Zhao and Y.S. Zhang, Sintering effect on microstructural evolution and mechanical properties of spark plasma sintered Ti matrix composites reinforced by reduced graphene oxides, Ceramics International, https: / / doi.org / 10.1016 / j.ceramint.2018.06.252 The invention provides a method for manufacturing a titanium / graphene composite with high thermal conductivity, in which a graphene layer is formed on the surface of titanium or titanium alloy by an electrochemical reduction process to form a composite material. The preparation method of the invention is simple, reliable, robust, and does not use a chemical reducing agent, which reduces the pollution of chemicals and reduces the one-step film formation method, and the prepared graphene layer is uniform and its thickness can be controlled. In this composite, the thermal conductivity is significantly improved and can extend the application range of titanium or titanium alloy. This research is only designed for surface properties and cannot be extended to the internal regions of the sample, while in the present research, all the structures of the produced samples have improved properties. CN106978606B China The invention provides a nanostructured titanium alloy. The nanostructured alloy is made by combining severe plastic deformation processes and non-severe plastic deformation type thermomechanical deformation steps, at least 80% of the grains in the developed structure have a grain size of 0.1 micron. Titanium alloys that can be used in accordance with the present invention include commercially pure titanium, Ti-6Al-4V, Ti-6Al-4V ELI, Ti—Zr or Ti-6Al-7Nb. The nanostructured titanium alloy in accordance with the present invention can be used to produce useful products with advanced material properties, including aerospace fasteners, aerospace structural components, medical applications such as spinal rods, screws, intramedullary appendages, bone plates and other orthopedic implants. For example, the invention can provide aerospace fasteners comprising a nanostructured Ti alloy having an ultimate tensile strength greater than 1200 MPa and an increased shear strength greater than 650 MPa. US20140271336A1 United States The invention provides a graphene / aluminum composite material, in which the amount of graphene in the composite is 0.5-1.0% by weight of the total composite material. Compared with the mechanical properties and electrical performance of pure aluminum, the mechanical properties and electrical performance of the graphene / aluminum composite material are improved to varying degrees. Graphene can be added to molten aluminum liquid in the state of graphene / aluminum intermediate alloy, the dispersion uniformity of graphene in the aluminum liquid is greatly improved, and accordingly, industrial volume production of graphene-modified aluminum wire cables is achieved by melt casting. A preparation method of the composite material includes the steps of mechanical mixing, low-temperature ball milling, vacuum separation, hot isostatic pressing, extrusion and the like. The technology is simple and controllable, and has low production cost. The preparation method is suitable for industrial production and market prospects.In this study, due to the separation of the powder metallurgy production stages, in addition to time, a large increase in production costs will be observed, while in the present study, the pressing and sintering processes are carried out simultaneously and with higher quality. CN105112700A China Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention Given the increasing number of industries that are sensitive to materials that have good resistance to hardness and wear properties, one of the best ways is to manufacture metal-based composites. This invention, taking into account the preservation of its original nature, which is to enhance the hardness and wear of CK45 steel through composite manufacturing, uses steel machining waste, which accounts for a large volume in the country's industries, in addition to the main objectives of this research, also looks at the environmental issue and recycling of waste. In this invention, first, after supplying the reduced graphene oxide and dispersing it in an ethanol solution, the shavings obtained from the machining of CK45 steel are milled and turned into powder and combined with an ethanol solution containing reduced graphene oxide and used. The spark plasma sintering (SPS) method has been used to manufacture the mentioned composite. This method, which is one of the methods for shaping metallic and ceramic materials, is used for sintering and synthesizing various compounds, including metallic, ceramic, and composite.Sintering at controlled temperature and pressure for a short time is based on the phenomenon of electrical discharge and the creation of an instantaneous high-temperature plasma in a small local area between powder particles in a fraction of a second. SPS technology has been introduced for sintering nanocrystalline materials with the lowest grain growth rate and the least negative impact on the particles. Explanation of shapes, maps and diagrams Figure 1 shows the schematic of the different stages of the experiment, Figure 2 shows the test results of the manufactured samples in terms of phases created in different stages, Figure 3 shows the results of the wear test of the manufactured samples in terms of weight loss. Also, the hardness test results of the manufactured samples are shown in Figure 4, and the scanning electron microscope images of the cast sample, the manufactured sample with reduced graphene oxide, and the manufactured sample without reduced graphene oxide are shown in Figure 5. A clear and precise statement of the advantages of the claimed invention over prior inventions. In this invention, a steel composite reinforced with reduced graphene oxide nanoparticles was fabricated using scrap recycling and plasma sintering, and according to the results obtained, it significantly improved the mechanical properties of spot welding. Side benefits of this design include recycling steel machining waste and reducing environmental pollution. Description of at least one implementation method for implementing the invention Railway and military industries related to simultaneous hardness and wear properties Explicit mention of the industrial application of the invention Used in the railway, military and automotive industries Research and development of recycling technology in applied industries

Claims

Complaint What is claimed: Claim 1) By producing 0.5 mm thick CK45 steel machining chips through a turning process and then converting it into powder using the ball mill method and combining it with 0.02 g of reduced graphene oxide, the CK45 / RGO composite was manufactured using the spark plasma sintering method at a temperature of 1200 °C, a pressure of 35 MPa and a duration of 3 minutes.

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