Recent Patents on Materials Science - Volume 10, Issue 2, 2017

Background: Friction and wear are one of the major causes of failure of mechanism and machines in the field of Engineering. To overcome this problem, lubricants are provided in the engineering system. Lubricants are derived from synthetic hydrocarbon blends or mineral oils. Lubricants help to minimize friction and wear in contacting surface in order to reduce friction and minimize power loss. In certain situation, lubricants fail to satisfy their lubricating properties. In order to improve the attributes of lubricants, such as improving anti-oxidation capability, thermal properties, and tribological characteristic, a few additives can be added to the base oil. Objective: In the field of tribology, nanotechnology offers the opportunity for improving the performance of lubricant oil using nano-additives. The addition of nanoparticles to base oil will enhance the certain characteristic of lubricant oil, such as improving friction and wear resistance, improving load carrying capacity etc. This review presents the nano-additives in the field of lubricant industry. This review covers the various nano-additives and their application in the field of lubricant industry. Method: With a thorough review of literature in the field of tribology, nanotechnology and lubricants, various nano-additives and their advantages are discussed.

Background: The interest for polymeric nanogels is entirely justified taken into consideration their diversity brought by the composition and their multiple applications, especially in the biomedical field. Nanogels can be defined as three-dimensional networks with interconnected pores and diameters below 100 nm. These materials exhibit distinct properties like swellability which can be useful for entrapping and further release of bioactive substances. Nanogels combine the characteristics of hydrogels (swelling capacity and retention of high amount of water, as well as tunable physicochemical properties) with those of nanoparticles (large surface area which facilitates adsorption and the possibility of being passed through the systemic circulation). Objective: This review highlights the latest inventions in the field of nanogels synthesis. Thus, the recent methods of preparation will be described as well as their use as nano-assemblies/nano-delivery systems in the biomedical field. Conclusions: There is an increasing interest in the study of nanogels due to their facile tailoring characteristics and the ability to encapsulate bioactive substances. In spite of that, there are a lot of issues that are necessary to assess the effectiveness of these materials regarding metabolism, biodistribution, toxicity, immunogenicity and pharmacokinetics.

Background: Heterojunction interface effect and wide light absorption are attracting many attentions for environmental application. Reduced Graphene Oxide (RGO)/semiconductor hybrids have showed very high photocatalytic activity than single one. RGO/CuS hybrids should be a competitive material with highly photocatalytic activity. Objective: This work focused on the synthesis and photocatalytic activity of the CuS nanoparticles composited with Reduced Graphene Oxide (RGO) and the roles of various operation parameters on the photocatalyric activity of the hybrids. Method: The RGO/CuS nanohybrids were synthesized by chemical solution reaction and characterized by various techniques to understand microstructural, physchemical, and photocatalytic properties. Results: The CuS nanocrystallines were uniform combined on the RGO surface. The CuS nanoparticles showed narrow bandgap that further narrowed as increasing rGO/CuS ratio. The CuS nanopartiles showed excellent photocatalytic activities. Incorporating RGO further enhanced the activities. Moreover, the increase in RGO/CuS ratio and decrease in initial solution pH also enhanced the activities. The higher activities of the hybrids were ascribed to the good carrier transfer at heterojunction interface that was confirmed by band energy level calculation and visible photoluminescence weakened with increasing RGO/CuS. The present article discussed some important patents related to CuS and its hybrids materials. Conclusion: RGO/CuS nanohybrids are promising photocatalytic materials in application of environmental decontamination.

Background: Injection mould has become an important industry. The traditional method of optimizing a product through artificial experience has been unable to meet the needs of the market. Moldflow can be used for defect analysis before injection molding. Objective: The external barrel of washing machine of injection process analysis was presented by Moldflow. Methods: Molding process of the external barrel of washing machine was analyzed under two kinds of gates and cooling channels by Moldflow. The differences between the two designs are compared, such as air traps, welt line, warping and mould temperature by Moldflow analysis. Results and Conclusion: The paper reviews various patents of injection mould for washing machine in the recent years, such as washing machine design, materials and structure. The reasonable molding process conditions were assessed and the design was obtained. The quality of a part can be promoted maximally, reducing the molding period. The results show that the CAE analysis has a strong guiding effect on the molding process.

Background: Light Weight High Entropy Alloys (LWHEAs). Objective: The purpose of this article is to report the processing challenges we have faced during the development of LWHEAs and to highlight the alloys compositions which can be successfully processed. Method: Both liquid and solid phase processing techniques were attempted to synthesize LWHEAs. Results: A total of 12 HEA compositions were processed in the current study. Theoretically feasible but difficult to process compositions also been highlighted (unsuccessful in terms of processing) for the benefit of researchers who wishe to explore them using different innovative processing methods. Microstructure and hardness results have been reported for all successfully processed systems. The secondary phases formed in the developed LWHEAs were analysed. In addition, changes in microstructure arising as a result of variation of alloying element combination as well as the alloy composition have also been discussed. Conclusion: LWHEAs with density less than aluminium alloys (~ 2.7 g/cc) and hardness much superior to both conventional aluminium and magnesium based alloys have been developed. Liquid phase disintegrated melt deposition route is more successful while solid phase routes need to be optimized.

Background: Subcritical crack growth is one of the main time-dependent behaviors in rocks. Double torsion testing has been adopted to determine subcritical crack propagation parameters for granite specimens during water interaction, the crack growth time dependence of granite is also discussed on the basis of fracture mechanics. Objective: The purpose of this article is to study the time dependent failure characteristic of granite during water rock interaction. Methods: According to the corrosion theory, the linearity regression analysis was carried out on the experimental data, the relations between the subcritical crack growth velocity V and the intensity factor K were obtained both in natural state and in saturated water. Meanwhile, according to rock fracture mechanics theory, the relations between crack relative length l/b and crack growth time t were studied based on the subcritical crack growth parameters. Results: The fracture toughness K decreases from 1.532 to 1.043 due to water effect. Meanwhile, the limit time of the specimen in saturated water is much less than that in natural state. Conclusion: The water rock interaction has speed up the subcritical crack growth. This research provides a basis for the time-dependent stability in rock engineering.

Background: The applications of the clay minerals in the various process industries are still relevant and closely related to their structure and composition. Objective: To study ways of selection, purification and subsequent modification of mineral clays to ensure a specific industrial use, being proposed, developed and applied a separation method of clay fractions called elutriation. Method: A granted process was based on the principle of Stokes' law (BR Patent 102013016298). For this we used four glass columns in series in which were applied a high flow of deionized water, associated with a Venturi device to obtain purified in natura clays. We repeated this procedure adding NaCl to previous solution considering a fixed flux rate. This process enabled selective separation of clays and impurities by size and density. Results: The efficient separation of crystalline phases has been verified qualitatively by both X-Ray Diffraction and Fluorescence. The main phases observed were montmorillonite, kaolinite and quartz. We also applied a quantitative analysis by means of the Rietveld refinement method of clay minerals, elutriated column by column, and also comparing elutriated and non-elutriated in natura samples. Conclusions: Results showed that there was a purification process with increasing montmorillonite phase up to 96% in mass at the same time that was noted the decrease content of the kaolinite and quartz phases. ICP-MS results showed that there was sodium incorporation, especially in the last columns, when using NaCl added to water solution.

Background: The development of resource and energy effective schemes for processing natural raw materials attracts increasing attention in the last decades. The scheme of the integrated processing of natural high-magnesian siderites (res. of 1 billion tonnes) developed and patented by our team allows obtaining several end products, the main of which are low-magnesian iron ore concentrate (Fetotal ≥ 58-60%, MgO ≤ 6-8%) and high-purity magnesia (MgO ≥ 98%). The middlings of processing high-magnesian siderites accordingly to this technology were found to be catalytically active in several well known reactions. Objective: So the objective of this research is to test the catalytic possibilities of the middlings of high-magnesian siderites processing in the water gas shift reaction and in the process of coal gasification by carbon dioxide. Method: The results of the laboratory experiments on the determination of the catalytic activity of the investigated material are presented in the article. Phase composition was determined by electron microscopy and X-Ray diffraction, chemical composition - by X-ray fluorescence and gas chromatography, specific surface - by the low temperature nitrogen adsorption method (BET method). Results and Conclusions: The middlings of high-magnesian siderites processing exhibit significant catalytic activity in the processes of coal gasification (conversion rate is 3-5 times higher in comparison with non-catalytic process) in the water gas shift reaction (the catalyst allows obtaining full conversion at the reactant load of up to 4000 h-1). The results of the research can be used in the realization of the principles of integrated high-magnesian siderites processing, including the possibility of obtaining an inexpensive catalyst for large-scale production.