Forensic engineering is the utilization of engineering skills or techniques to the investigation of material components that do not perform as intended during service. It usually deals with accidents, disasters and product failure of all kinds with an intention to provide solution. Quite often forensic materials engineers while dealing with it are focusing on two aspects; whether or not the appropriate engineering or quality standards have been followed during production process and whether the failure results from use or abuse.
Metal failure analysis are well established today simply because most have been used in service for many years, those of families of other materials especially failures of polymeric and elastomeric products are poorly published as these are recently introduced as engineering materials. Whatever the situation, material cannot be prevented from failure but root-cause analysis would help to prevent from known causes.
This presentation highlights the principal approach for the analysis of failed polymeric components. In the approach we mainly focus on three aspects, such as
* the parallels between failures in different materials - For engineering polymeric materials adequate properties database are not available to check whether or not a particular material is fit to be used under a specified set of circumstances. Therefore, comprehensive searches are being made to look for the track record of parallel product failures that already have been determined and causes established.
* IDprevious examples of similar failures - It provides a context for a previous investigation that can not only help resolve ambiguities but also aid designers in selecting materials with knowing the environment in which products have to perform reliably.
* alternative interpretations by other investigators - The role of alternative failure analysis may not be similar or may not provide detail information. Therefore assumptions on interactive effect may require to make for root cause analysis.
Particularly, in presentation, emphasis will be given to understanding polymeric materials component failures and the principles of failure analysis to discuss the unified approach of integrating the failure mechanism within the products which fail as case studies. Some challenges in current approaches are also presented.
From the process industry such as petroleum refining and petrochemicals to vehicles, heat exchangers are used to efficiently exchange thermal energy between the two fluids. Depending on the fluids during operation, clogging or deposits cause a decrease in the heat transfer efficiency, a decrease in the flow rate of the working fluid, and an increase in the differential pressure. As a result, the operating capacity is reduced. In this case, the heat exchanger needs to be cleaned. In this paper, a case study is presented that describes the possibility of the occurrence of corrosion of the aluminum alloy plate fin type heat exchanger by methanol solution used as a cleaning agent. The corrosion characteristics of the aluminum construction material were evaluation in the laboratory and countermeasures against corrosion then were implemented on the plant.
Global carbon dioxide (CO2) concentration in the atmosphere is continuously increasing due to excessive greenhouse gas emissions, worsening global warming, and climate change. The conventional method to capture CO2 from stationary industrial sources is liquid amine absorption, but its regeneration process is energy-intensive and poses risks of solvent losses. One feasible alternative solution is the use of solid adsorbents prepared by immobilizing amines onto porous substrates with high surface area. We investigated the use of natural bentonite and activated carbon coated with aminated pectin as adsorbents for CO2 capture using a pure CO2 source. The pectin was aminated by initiating the opening of the polysaccharide chains and introducing tetraethylenetetramine as the aminating agent before coating onto the porous substrates. The coating solution was analyzed using nuclear magnetic resonance and Fourier transform infrared spectroscopy to confirm the amination of pectin. The surface morphology of the adsorbents was characterized using scanning electron microscopy to reveal attachment of the modified pectin onto the substrates. The crystallinity of the coated substrates was also studied using X-ray diffraction. The effect of coating aminated pectin on the CO2 adsorption capacity of natural bentonite and activated carbon at 5% breakthrough was determined and discussed.
DME (Dimethyl Ether) is the future environmental friendly fuel. Some parts of equipment for transporting the DME are using rubber as a hoses or seals. This research is about the using of natural rubber for those applications. The influential part in the manufacture of natural rubber products are fillers. The use of filler depends on what the product will be made. DME nature have high permeability and easy to absorb into a rubber and plastic. In such of that, the rubber or plastic could be damaged and not durable. In order to determine the type of degradation, the number of samples were immersed in liquid DME. The ratio of the loading of carbon black/silica filler in natural rubber was varied. DME causes two types of degradation, namely absorption and extraction . The addition of filler composition can reduce the absorption and extraction, which can cause a reduction in the percentage decrease in the value of the change in mass and a decrease in tensile strength. On the other hand, the addition of filler composition will increase the changes of hardness. The higher filler loading, will increase the crosslink density and lower Scorch time. The presence of silica further is to enhance the crosslink density as well as to lower Scorch time. Therefore, the presence of silica affects on the decreasing of the swelling level and shrinking. In general, the presence of silica filler in the mixture will be slightly lowering the tensile strength, but not affecting the elongation at break. The presence of silica before and after soaking with DME will increase hardness.
Constructing mass production method of graphene is essential for practical usage of this remarkable material. Direct exfoliation of graphite in liquid is the promising approach for production of high quality graphene. However, this technique has three huge obstacles to be solved; limitation of solvent, low yield and low exfoliation degree. Here, we found that soluble graphite produced by mechanochemical reaction with salts overcomes above three drawbacks. The soluble graphite was exfoliated into 100% monolayer graphene with more than 10 % yield in five min. of sonication. Surprisingly, the modified graphite was easily exfoliated in low-boiling point solvent such as acetone, alcohol and water without an aid of surfactant. Molecular simulation revealed that the salt is adsorbed to the active carbon at the graphite edge. In the case of weak acid salts, the original bonding nature between alkali atom ion and the base molecule is kept after the reaction. Thus, the alkali metals are easily dissociated in polar solvent, leading to negative charging of graphene. This phenomenon enables the exfoliation of graphite in low boiling point solvents. The approach proposed here opens up a practical usage of the attractive 2D materials.
