Papers by Keyword: Materials Engineering

Abstract: The promise of transforming wastes from the Azores into building materials is the focus of this research. The insulation properties of some of these materials can be advantageous to the building construction sector. These materials are upcycled into non-structural components of the building such as panels for ceilings and walls as a factor to control thermal comfort economically. In this paper, insulation panels using cryptomeria waste from the carpentry industry were developed and experimentally evaluated in terms of conductivity for further study of their thermal properties, as well as life cycle analysis. Sodium silicate was used as a primary binding material along with these treated materials. The different composite panels made from the waste and surplus materials are expected to be analysed in Test cells that are built in Azores using this together with other wastes available in the region. These panels will be tested for longer periods in these test cells subjected to the local climatic conditions. The results of thermal conductivity are promising for the two composites sampled.

Abstract: This paper reviews the results of gallium (Ga) additions on the properties of Lead (Pb)-free solder alloys in terms of the solderability, microstructure and mechanical properties. Throughout the review, it is proven that when 0.5% of Ga is added, the shear force is improved and the grain size of the solder has refined remarkably. Besides, the addition of Ga has significantly suppressed the interfacial intermetallic compounds (IMCs) formation at solder/Copper substrate interface. This is caused by the formation of the Cu₂Ga phase around the joint surface during solidification which decrease the growth rate of the IMCs layer. In fact, the enhancement in the mechanical aspect can also be affiliated with the improvement of the IMCs of the solder due to the addition of Ga. Moreover, Ga element also added to act as solid solution strengthening in β-Sn matrix. Furthermore, the addition of Ga element definitely decreases the melting temperature of Pb-free solder in Sn-0.7Cu Pb-free solder. As Ga addition also improve the oxidation resistance and reduce the surface tension of the solder, thus the solderability of the Pb-free solder alloys is slightly improved.

Abstract: This work provides a method to recover monolayer metal values having nanoparticle in size from spent metalized graphite brushes. The recovered metals are supported on porous glassy carbon substrate by chemical or electro deposition process. The chemical method involves crushing and grinding of the spent brushes to pass 200 mesh. Magnetic separation removed magnetic susceptible metals such as iron. Nonferrous metals were leached using 3N nitric acid in hot conditions. Hydroxide gel of the dissolved metals generated with 1N ammonium hydroxide. The carbon substrate was multi-impregnated with metals hydroxide 3-4 times. In each time, the loaded carbon was dried. Free metals on the carbon substrate are obtained by reducing the hydroxide with hydrazine hydrate or by thermal reduction using hydrogen gas at 900°C. In the electro deposition process, ground spent brushes were packed in a polyethylene cloth used as anode. The electrolyte is 3M of sulfate salt of the metal of concern. Pulse current cyclic voltmetric technique was applied to control the particle diameter and thickness of the deposited metal. Results revealed that monolayer silver and copper of nanoparticles has been successfully prepared from spent metalized graphite brushes. Electro deposition is more friendly environment procedure and more convenient, less cost and more precise.

Abstract: With the advanced materials industry, makes this especially machinery manufacturing industry has witnessed rapid development and become one of the very important part, therefore, material engineering colleges focus on the development has also become one of the disciplines. Train and improve their practical ability to adapt to the needs of society has become an important part of college students training, this thesis explores the materials engineering students' professional training system establishment, the students presented material class materials processing skills training methods Manufacturing engineering training through high students' practical ability and engineering sense.

Abstract: The ligament injury is the common sport injury in the athletic sports training, the progress and development of suture technique provides a good guarantee for the treatment of tear and rupture tendon, ligament tissue units, the use of absorbable suture materials can prevent in partly risk of Treatment induced by no absorbable suture materials. Therefore, the absorbable suture materials are generally favored by both doctors and patients. The absorbable sutures can be degraded into soluble product in the body, thereby it reducing the patients with second operation pain and minimize patient suture in scar formation, it get the more and more favor of both doctors and patients. The different materials of absorbable sutures were appeared, which meet the people's needs to some extend.

Abstract: Based on the comparative analysis on the undergraduate program for specialty in materials engineering in the two universities at home and abroad, the courses design planning and some courses characteristic were discussed. Mode of cultivating innovative students and application-oriented students were also discussed with comparing the differences at the education procedure. Scientific and reasonable basic courses in general education and major courses in specialty are considered to be fundamental for training innovative students and application-oriented students. It is pointed out that cultivating of students with innovative and qualified ability are contributed to scientific collaborations with reasonable courses planning, hardware and facilitates, courses management and interactions between lecturers and students at class.

Abstract: The paper discusses the mathematics of pattern indexing and its applications to recognition of visual patterns and classification of objects that are represented by objects-properties matrices. It is shown that (a) pattern indexes can be represented by collections of inverted patterns, (b) solutions to pattern classification problems can be found as intersections of inverted patterns and, thus, matching of original patterns avoided.

Abstract: Materials engineering plays vital role in Solid Oxide Fuel Cell (SOFC) technology. For example, engineered porous materials are needed to support delicate electrolyte membranes, where mechanical integrity and effective diffusivity to fuel gases is critical; and to construct fuel cell electrodes, where an optimum combination of ionic conductivity, electronic conductivity, porosity and catalyst distribution is critical. Material engineering also underpins selection of cell designs and material systems to minimise failure, particularly during transient operations such as thermal cycling. The paper will address these issues, making reference to high temperature (>900C) SOFCs for integration with gas turbines, and metal supported SOFCs designed to operate at temperatures of 500-600C.

Abstract: Rapid advances in technology have blurred traditional boundaries between engineering disciplines and forced mechanical engineering graduate courses to embrace new subject areas. These are not negative influences, but are simply a healthy response to rapidly advancing technologies. A particular example is the combining in one study program, studies of different engineering and structural materials (including composite materials, ceramics, polymers, etc.) and methods and technologies of brazing, joining by welding, bonding by glue, etc of these materials. Among all engineering programs, materials and mechanical engineering requires huge laboratories and expensive facilities, as students need to develop practical experience. In order to maintain an educational standard and quality, a university is forced to look for alternatives to handson practical laboratories. One of the alternatives is to utilize a wide variety of computer-aided learning packages and the simulation of physical-chemical processes in a welding pool and near to its border. This paper sets forth a case for integrating aspects of materials and joining technologies throughout a graduate curriculum.

Abstract: In this paper are physicochemical bases of self–lubricating mechanism of porous sliding bearings is presented. Up to now information about this, which took into consideration mainly aspects, e.g. mechanical, thermal, hydromechanical etc, and knowledge of chemical elements concerned with the course of chemical reactions into diphase system fluid – solid (porous) was completed.