Topic Review
Roll Bonding Processes
The roll bonding (RB) process involves joining of two or more sheets of similar or dissimilar materials at various temperatures. The process requires rolling through a pair of rollers under adequate pressure resulting in the bonding of sheets. The process is categorized into three types, i.e., cold, hot, and warm roll bonding based on the ranges of the processing temperature which in turn is related to the recrystallization temperature.
  • 2.0K
  • 03 Sep 2021
Topic Review
Artisanal and Small-Scale Gold Mining
The aim of this work is to explain the concepts of sustainability with respect to small artisanal gold mining. For this, a qualitative approach with a descriptive scope was used, for which the bibliographic review technique was conducted. In this sense, articles, theses, books and institutional documents, and any contribution related to the research topic were taken into consideration. Likewise, this documentation contributed to the delimiting aspects that allowed a contrast between the proposed definitions and small artisanal mining in the Northeast Antioquia region in Colombia. Based on the reviewed sources, different needs were recognized in artisanal small-scale gold mining in Northeast Antioquia that still need action. In conclusion, through the exposition of sustainability theories, three common factors were identified within the various positions that were raised—the environmental, economic, and sociocultural dimensions. 
  • 614
  • 27 Aug 2021
Topic Review
Fatigue Shear-band in Metallic Glass
Metallic glass (MG) is a class of metallic material fabricated by the fast-cooling during solidification. This alloy lacks the long-range order characteristic and the crystalline defects including grain boundaries and dislocations. The unique structural feature makes some mechanical properties of MG obviously superior than conventional crystalline alloys, such as strength, hardness, elastic limit, wear resistance, etc. It is estimated that ~90% of all mechanical failures in the structural materials are caused by fatigue. Thus, the fatigue property is an important evaluation index before a new structural material application. Without the dislocations and grain boundaries, the plastic deformation of MG occurs in the form of atomic clusters operation at room temperature, eventually leading to the generation of shear band. It is found that the fatigue damage and fracture of MGs were dominated by shear band. As a result, understanding how shear band evolution under cyclic loading is important for improving the fatigue performance of MGs.
  • 641
  • 16 Jul 2021
Topic Review
Production of Electrolytic Manganese Dioxide
The ferromanganese (FeMn) alloy is produced through the smelting-reduction of manganese ores in submerged arc furnaces. This process generates large amounts of furnace dust that is environmentally problematic for storage. Due to its fineness and high volatile content, this furnace dust cannot be recirculated through the process, either. Conventional MnO2 production requires the pre-reduction of low-grade ores at around 900 °C to convert the manganese oxides present in the ore into their respective acid-soluble forms; however, the furnace dust is a partly reduced by-product. A hydrometallurgical route is proposed to valorize the waste dust for the production of battery-grade MnO2. By using dextrin, a cheap organic reductant, the direct and complete dissolution of the manganese in the furnace dust is possible without any need for high-temperature pre-reduction. The leachate is then purified through pH adjustment followed by direct electrowinning for electrolytic manganese dioxide (EMD) production. An overall manganese recovery rate of >90% is achieved. 
  • 4.4K
  • 08 Jul 2021
Topic Review
Flake Powder Metallurgy
Flake powder metallurgy (FPM) including different processing routes, conventional FPM (C-FPM), slurry blending (SB), shift-speed ball milling (SSBM), and high-shear pre-dispersion and SSBM (HSPD/SSBM). The name of FPM was derived from the use of flake metal powders obtained by low-speed ball milling (LSBM) from spherical powder. The uniformity of reinforcement distribution leads to increased strength and ductility. Powder is the basic unit in PM, especially advanced PM, and its control is key to various new PM technologies. The FPM is a typical method for finely controlling the powder shape through low-energy ball milling (LEBM) to realize the preparation of advanced material structures. 
  • 2.0K
  • 23 Jun 2021
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