Papers by Keyword: Metal

Abstract: Ni and Ni-containing nanoparticles exhibit promising magnetic properties. In a preliminary experiment, these nanoparticles aggregated after synthesis. Because nanoparticle aggregation may degrade their unique properties, a method to prevent their aggregation is required. In this study, Ni-Pt nanoparticles were synthesized and coated with silica to suppress aggregation. A colloidal solution of Ni-Pt nanoparticles was synthesized in water exposed to air using nickel(II) acetate tetrahydrate (Ni source), hexachloroplatinate(IV) hexahydrate (Pt source), sodium borohydride (reducing agent), and citric acid (stabilizer). Silica-coated Ni-Pt nanoparticles (Ni-Pt/SiO₂) were synthesized by adding a tetraethylorthosilicate (TEOS)/ethanol solution to the colloidal Ni-Pt nanoparticle solution. The morphology of the Ni-Pt nanoparticles varied with reaction time. The Ni-Pt/SiO₂ nanoparticles consisted of Ni-Pt cores and SiO₂ shells, with their morphology dependent on the TEOS concentration. Furthermore, the Ni-Pt/SiO₂ nanoparticles were more dispersed than the uncoated Ni-Pt nanoparticles, suggesting that the silica coating suppressed aggregation.

Abstract: Sand casting is a metal casting process to make a component by pouring molten metal into the sand mold. The casting process, the sand is the fundamental material used for mold making. The sand used is generally silica sand, river sand, mountain sand, and beach sand. The sand for molding must have requirements such as having formability, suitable permeability, good distribution of sand grain size, resistance to high temperatures, suitable binder composition, and sand must be cheap. This study investigated to determine the potential of Krueng Mane river sand in Aceh Indonesia for its possible use for metal casting. The important properties studied are moisture content, total clay content, grain fineness number, and grain shape. Tests are carried out following the standards and procedures defined by the American Foundrymen’s Society (AFS). Results obtained revealed that the river sand has average moisture content of 7.78 %, clay content of 3.20%, and grain fineness number (GFN) of 46. Krueng Mane river sand will be suitable for casting of casting of light steel, heavy grey steel, medium grey iron, and non-ferrous metals, with the addition of binding agent in suitable proportion.

Abstract: Additive Manufacturing (AM) [1] is playing every day a bigger role in the automotive industry because of its cost competitiveness, short delivery lead times and potential for design flexibility and optimization. Plastics and polymers are the most common materials used to produce AM parts in this sector, however metal AM is increasing its importance as there are specific applications that require mechanical characteristics that can only be achieved with metals such as stainless steel, titanium, hard steel, copper, aluminum, and others. There is an increasing number of metal AM technologies and Original Equipment Manufacturers (OEMs) competing in the industry with a very widespread list of advantages and disadvantages of each of them. We are at a point where automotive manufacturers need to make a complex decision on which metal AM equipment to purchase. This paper describes the main metal AM technologies and highlight the advantages and disadvantages of each of them. Additionally, three of the most competitive Metal AM technologies are compared: Powder Bed Fusion (PBF), Metal Filament Deposition Modeling (MFDM) and Bound Metal Deposition (BMD) on a specific experimental sample. For this study, a very common and representative automotive part has been chosen that is well suited to be printed in metal and can be manufactured in the three chosen technologies. A nozzle from the automotive body plant used to distribute accuratey a sealant bead onto a body panel before the final assembly operation was selected. These sample parts have been trialed for function and evaluated in general terms from a quality point of view. The conclusions included in this paper will help the automotive industry players understand which technology to use for this specific part and other parts with similar characteristics. Additional work will focus on specific quality characteristics such as material composition, mechanical properties, dimensional accuracy, and specific defects found to compare these technologies in detail. Furthermore, a selection of other automotive parts and technologies will be necessary to enlarge the knowledge on the application of metal AM on this field.

Abstract: Metal matrix composite materials are a novel material generation capable of handling the implementation of advanced technology's growing needs. Aluminium-based metal matrix composites are widely used in automobiles and aerospace, as well as other industries, including defence and marine systems, due to their relatively low processing costs as compared to other matrices such as magnesium, copper, titanium, and zinc. Ceramic particles were shown to improve mechanical properties like hardness and tensile strength. The product's compactness and price, however, were both boosted. Agricultural waste materials are widely available today in significant amounts, and researchers have focused on using wastes as reinforcing fillers in composites to counteract pollution. Rice husk ash added to an aluminium alloy matrix increases the composite's mechanical properties while also increasing its wear resistance. According to scanning electron micrographs of the composite, the ash from rice husks is evenly distributed all over the aluminium matrix. Wear can vary from micro-cutting to oxidation at high temperatures in an aluminium alloy. Strain fields are produced and composite material wear resistance is improved due to the difference in coefficients of thermal expansion between the matrix and reinforcing materials. This study focuses on the production process, properties, and performance of an aluminium alloy composite incorporating rice husk ash, which has high hardness as well as wear resistance.

Abstract: Corrosion is considered as one of the serious challenges that deteriorates the material properties of metals and alloys. In this research study, the inhibition of aluminum in 1M NaOH by Phoenix Dactylifera tree fiber extract was studied in the temperature range 308.15-318.15 K using the standard gravimetric technique. The performance evaluation was monitored using inhibition efficiency (% IE) and the IE increased as the concentration of Phoenix Dactylifera extract increased, reaching 82.55 % at 0.15 mg/ml . An inversely proportional relationship was found to exist between temperature and IE. The corrosion inhibitory effect was fitted with the Langmuir isotherm, with a correlation coefficient of R² ≥ 0.950. The inhibitor sorption was confirmed to be spontaneous as Gibbs free energy was reported to be negative. The effectiveness of the green corrosion inhibitor proved to be a potential solution for protection of aluminum under alkaline conditions.

Abstract: At present, methanol is one of the most basic organic chemical raw materials and energy storage media. With the development of chemical technology and energy storage technology, its application becomes more and more extensive, and the methanol market prospects are unlimited. Industrial-scale methanol is generally prepared by using synthesis gas containing hydrogen, carbon monoxide, and carbon dioxide as raw materials and reacting under a certain pressure, temperature, and catalyst. Therefore, the development of the methanol industry largely depends on the development of catalysts and the improvement of their performance. Metal catalysts are mainly used in the industry for reaction. This article reviews several metal catalysts used to synthesize methanol from syngas. Copper-based and iron-based catalysts are widely used, and the emerging rhodium and its ligand catalysts exhibit good catalytic performance in low-temperature catalysis. In the future, the scientific research team will focus on in-depth research on preparation methods, active centers, catalytic reaction kinetics, durability, metal ligands, raw material prices, etc., to lay a solid foundation for the industrial application of syngas to methanol in advance.

Abstract: In order to predict the effect of the Marangoni convection and the morphology of melted stainless steel powder, during the selective laser melting (SLM) process, a transient three-dimensional numerical model is developed at the mesoscale. The evolution of the temperature and velocity fields’ is then studied. The initial powder bed distribution is obtained by the discrete element method (DEM) calculation, and the temperature distribution and the molten pool shape deformation are calculated and analyzed by the Ansys-Fluent commercial code. The molten pool shape is obtained by considering the influence of Marangoni convection on the internal flow behavior. The recoil force was not considered in our calculation. As main results, a slight deviation between the position of the maximum temperature of the molten pool and the center of the laser spot is observed. The direction of the heat diffusion is more likely to be horizontal and the flow centrifugal, which causes the melt track to be wide. Finally, the Marangoni convection is the main driver of the flow.

Abstract: In the forging industry, rolling is used to produce ring forgings, which are widely used in power and nuclear engineering. According to the technical conditions and established practice, large ring forgings are made using the operations of precipitation, piercing and rolling out with a striker on the mandrel.

Abstract: In this paper the temperature fields in the zone of processing of paint coatings by laser radiation of a sample of the metal skin of aircraft gliders with selective (layer-by-layer) removal are researched. The performed theoretical studies and numerical calculations made it possible to carry out practical tests and develop conditions under which the physical effect of laser energy causes minimal damage to the alloys and composites of the sample, as well as to assess the effect of the laser on the properties of materials used in the aerospace industry. The obtained results are reflected in the technology of laser selective removal of paint coatings from metal and composite skin of aircraft gliders.

Abstract: Vat photopolymerization is one of additive manufacturing and also known as photo-curable three-dimensional printing technology. It uses light energy with the proper wavelength to expose on the liquid photo-curable resin inducing the photopolymerization process and resulting in solidification layer-by-layer. The building method is classified into two ways: free-surface and constrained-surface. The advantage and disadvantage of both methods are described and analysed according to the different material property and requirement. The basic composition for photo-curable resin consists of photo-initiator and monomer. Adding powder into photo-curable resin makes the photo-curable slurry. Literatures report that high density powder such as zirconia oxide or Inconel 718 is suitable for free-surface building method because of poor suspension. However, the volume percentage in the slurry is less than 50% causing the higher shrinkage ratio and inaccuracy after sintering process. The coupling agent may increase the suspension of powder in slurry but experimental result shows that it still cannot improve the success rate in the constrained-surface building method. Therefore, this study proposes a combination method to overcome the difficulty of making high density ceramic or metal part. In addition, the sintering process is a key factor to obtain the high dense part with no crack occurrence and desirable microstructure. The optimized sintering parameters for zirconia oxide and Inconel 718 are also introduced.