Advanced Materials Research Vol. 1175

Abstract: In this study, sheet-like MnO₂/ZnO microflower (MnO₂/ZnO) loaded on cotton fabric was prepared via a facile reflux-thermal deposition combined technique. The coated fabric and as-fabricated particles were analyzed through numerous characterization techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), tensile strength, Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) as well as photoluminescence (PL) measurements. The optical trait of the ZnO was significantly improved by the addition of MnO₂ that extended reflectance edges in the visible light region. The treated cotton fabric greatly inhibited the growth of Escherichia Coli bacteria and Aspergillus Niger fungi as testified by the zone of inhibition surrounding the fabric samples. The self-cleaning outcomes also demonstrated that 3% MnO₂/ZnO/fabric presented highest visible light photodegradation of phenol among the samples. The promising performance of the cotton fabric coated by MnO₂/ZnO composite was related to the reactive oxygen species produced by the heterojunction photocatalytic mechanism under exposure of visible light.

Abstract: In this study, high-cost Cr and Ni components of 202 austenitic stainless steel were reduced, low-cost Mn was added, and the amount of martensite and the mechanical properties were evaluated according to the rolling temperature and rolling degree. Part of the austenite was deformed by rolling into α′-martensite. As the rolling degree was increased, more martensite was generated; and at the same rolling degree, as the rolling temperature decreased, more martensite was generated. Up to a rolling degree of 33 %, the amount of martensite rapidly increased; thereafter, it gradually increased. In particular, the amount of martensite at a rolling temperature of-196 °C was similar to that after the rolling degree of 33 %. As the rolling temperature decreased and the rolling degree increased, both the Vickers hardness and tensile (yield) strength increased, while the elongation rapidly decreased.

Abstract: The cutting fluid plays a significant role in minimizing heat generation and chip removal process during the machining of materials, hence improving tool life and surface finish of the workpiece. Many researchers have focused on minimum quantity lubrication (MQL) among the existing methods on the application of the coolant as it reduces the usage of coolant by spurting a mixture of compressed air and cutting fluid in an improved way instead of flood cooling. The MQL method has demonstrated to be appropriate as it fulfills the necessities of ‘green’ machining. Additionally, considering current environmental issues and provisions for safe healthy working conditions at the workplace, it is important to divert machining processes towards an eco-friendly path. Hence, the focus of research has been shifted to MQL using eco-friendly lubricants for green and sustainable manufacturing processes. In this review paper, the effect of different vegetable oil-based biodegradable coolants like castor oil, coconut oil, palm oil, etc. for different machining process parameters like cutting force, cutting temperature, surface finish, tool wear, etc. has been reviewed. It is observed that proper selection of cutting parameters along with lubricant through MQL can provide enhanced machinability to get desired outputs.

Abstract: Forging tools must be able to withstand very strong mechanical, thermal, tribological, and chemical stresses. The extent to which a tool can withstand these stresses depends on the material used and its pre-treatment as well as the heat and surface treatment, i.e. the load capacity. The ratio of stress to load capacity determines how high the tool life of a forging tool is. This paper deals with the variations in the tool life of forging tools using the example of a specific industrial stage sequence and production conditions. Due to a large number of influencing variables that have an effect on the tool during the entire tool life history, the focus of this work is placed on influencing variables of the forming process. Based on real production parameters of a forging company, which are recorded during a period for the investigation, the process data are analyzed about an influence on the tool life. The investigation focuses on four influencing variables, namely the subjective assessment of the end of the tool life, the interaction between the forming stages, production interruptions, and the cooling and lubrication of the forming tools. For the parameters that are not yet recorded during the trials, promising available measurement methods are identified and tested under laboratory conditions. One example of this is the recording of the actual spray quantities that are sprayed onto the tool surface before the forming process. The results of the investigations show that the tool life fluctuations can be reduced by about 16% and as a consequence, the average tool life can be increased by about 13%.

Abstract: Concrete is one of the most used construction materials worldwide. It is known to be a strong and durable material at a reasonable price. The most well-known problem in concrete is the cracks, which affect the service life of the concrete structures and leads to consumes higher costs through maintenance. Cracks allow penetrating any ions into the concrete resulting in other big problems such as corrosion of steel reinforcement, sulphate attack, carbonation, alkali-aggregate reaction, etc. It is impossible to prevent the formation of cracks, therefore they can be controlled or repaired using a variety of methods. Nowadays, self-healing is one of the widely recognized techniques to improve concrete's long-term durability. Healing agents such as bacteria, chemical compounds, and polymers are utilized. In this method, with the help of a healing agent, the cracks start to heal autonomously during crack formation. Since Bacteria is the most used material for healing concrete, self-healing concrete is also known as bacterial-concrete or bioconcrete. This article provides an overview of self-healing concrete including describing the system, process, durability, and mechanical properties of healed concrete.

Abstract: Modifying asphalt mixtures with recycled components is common practice due to their environmental and economic merits. However, due to the oxidized air-blown asphalt binders in recycled asphalt shingles (RAS) and aged binders in reclaimed asphalt pavement (RAP), adopting RAP and/or RAS as recycled components in asphalt mixtures influences the performance of the overall asphalt binder in these mixtures. The percentages of recycled components and performance grade (PG) of virgin asphalt binders (VABs) in the asphalt mixtures govern the performance of the overall asphalt binder. Therefore, the main idea of this study was to investigate the effect of the percentages of RAP/RAS and PGs of the VABs on the load- and non-load-associated cracking resistance of the extracted asphalt binders (EABs) from field cores. Rheological tests were performed on the EABs to assess the load-associated cracking (fatigue cracking) and non-load-associated cracking (low-temperature and block cracking) resistance. The VAB's PGs, mixtures' ages, and the percentages of RAP/RAS affected the EABs' cracking resistance. When compared to EABs from mixtures with lower amounts of RAP, employing RAS in the asphaltic mixtures improved EABs' resistance to fatigue and block cracking. However, using RAS deteriorated EABs' resistance to low-temperature cracking. Increasing the RAP's percentage in the asphaltic mixtures decreased the cracking resistance of the EABs. Strong relationships were established between EABs' load- and non-load-associated cracking resistance.