Auswahl der wissenschaftlichen Literatur zum Thema „The high-tilting shovel is mostly utilised in industrial area“

Both aviation and land based turbine components such as vanes/nozzles, combustion chambers, liners, and transition pieces often degrade and crack in service. Rather than replacing with new components, innovative repairs can help reduce overhaul and maintenance costs. These components are cast from either Co-based solid solution superalloys such as FSX-414, or Ni-based gamma prime precipitation strengthened superalloys such as IN738. The nominal compositions of FSX-414 and IN738 are Co-29.5Cr-10.5Ni-7W-2Fe [max]-0.25C-0.012B and Ni-0.001B-0.17C-8.5Co-16Cr-1.7Mo-3.4Al-2.6W-1.7Ta-2Nb-3.4Ti-0.1Zr, respectively. Diffusion brazing has been used for over four decades to repair cracks and degradation on these types of components. Typically, braze materials utilized for component repairs are Ni and Co-based braze fillers containing B and/or Si as melting point depressants. Especially when repairing wide cracks typically found on industrial gas turbine components, these melting point depressants can form brittle intermetallic boride and silicide phases that effect mechanical properties such as low cycle and thermal fatigue. The objective of this work is to investigate and evaluate the use of hypereutectic Ni-Cr-Hf and Ni-Cr-Zr braze filler metals, where the melting point depressant is no longer B, but Hf and/or Zr. Typically, with joint gaps or crack widths less than 0.15mm, the braze filler metal alone can be utilized. For cracks greater than 0.15mm, a superalloy powder is mixed with the braze filler metal to enable wide cracks to be successfully brazed repaired. As a means of qualifying the diffusion braze repair, both metallurgical and mechanical property evaluations were carried out. The metallurgical evaluation consisted of optical and scanning electron microscopy, and microprobe analysis. The diffusion brazed area consisted of a fine-grained equiaxed structure, with carbide phases, γ [gamma] dendrites, flower shaped/rosette γ-γ′ [gamma-gamma prime] eutectic phases and Ni7Hf2, Ni5HF, or Ni5Zr intermetallic phases dispersed both intergranularly and intragranularly. Hardness tests showed that the Ni-Hf and Ni-Zr intermetallic phase only has a hardness range of 250Hv to 400Hv; whereas, the typical Cr-boride phases have hardness ranges from 800Hv to 1000Hv. Therefore the hardness values of the Ni-Hf and Ni-Zr intermetallic phases are 2.5–3.2 times softer than the Cr-boride intermetallic phases. As a result the LCF properties of the wide gap Ni-Cr-Hf and Ni-Cr-Zr brazed joints are superior to those of the Ni-Cr-B braze filler metals. The mechanical property evaluations were tensile tests at both room temperature and elevated temperature, stress rupture tests from 760°C–1093°C and finally low cycle fatigue [LCF] tests, the latter being one of the most important and severe tests to conduct, since the cracks being repaired are thermal fatigue driven. At the optimum braze thermal cycle; the mechanical test results achieved were a minimum of 80% and sometimes equivalent to that of the base metals properties.

Both aviation and land based turbine components such as vanes/nozzles, combustion chambers, liners, and transition pieces often degrade and crack in service. Rather than replacing with new components, innovative repairs can help reduce overhaul and maintenance costs. These components are cast from either Co-based solid solution superalloys such as FSX-414, or Ni-based gamma prime precipitation strengthened superalloys such as IN738. The nominal compositions of FSX-414 and IN738 are Co-29.5Cr-10.5Ni-7W-2Fe [max]-0.25C-0.012B and Ni-0.001B -0.17C-8.5Co-16Cr-1.7Mo-3.4Al-2.6W-1.7Ta-2Nb-3.4Ti-0.1Zr, respectively. Diffusion brazing has been used for over four decades to repair cracks and degradation on these types of components. Typically, braze materials utilized for component repairs are Ni and Co-based braze fillers containing B and/or Si as melting point depressants. Especially when repairing wide cracks typically found on industrial gas turbine components, these melting point depressants can form brittle intermetallic boride and silicide phases that effect mechanical properties such as low cycle and thermal fatigue. The objective of this work is to investigate and evaluate the use of hyper-eutectic Ni-Cr-Hf and Ni-Cr-Zr braze filler metals, where the melting point depressant is no longer B, but Hf and/or Zr. Typically, with joint gaps or crack widths less than 0.15mm, the braze filler metal alone can be utilized. For cracks greater than 0.15mm, a superalloy powder is mixed with the braze filler metal to enable wide cracks to be successfully braze repaired. As a means of qualifying the diffusion braze repair, both metallurgical and mechanical property evaluations were carried out. The metallurgical evaluation consisted of optical and scanning electron microscopy, and microprobe analysis. The diffusion brazed area consisted of a fine-grained equiaxed structure, with carbide phases, γ [gamma] dendrites, flower shaped/rosette γ-γ′ [gamma-gamma prime] eutectic phases and Ni7Hf2, Ni5HF, or Ni5Zr intermetallic phases dispersed both intergranularly and intragranularly. Hardness tests showed that the Ni-Hf and Ni-Zr intermetallic phase only has a hardness range of 250Hv to 400Hv; whereas, the typical Cr-boride phases have hardness ranges from 800Hv to 1000Hv. Therefore the hardness values of the Ni-Hf and Ni-Zr intermetallic phases are 2.5–3.2 times softer than the Cr-boride intermetallic phases. As a result the LCF properties of the wide gap Ni-Cr-Hf and Ni-Cr-Zr brazed joints are superior to those of the Ni-Cr-B braze filler metals. The mechanical property evaluations were tensile tests at both room temperature and elevated temperature, stress rupture tests from 760°C—1093°C and finally low cycle fatigue [LCF] tests, the latter being one of the most important and severe tests to conduct, since the cracks being repaired are thermal fatigue driven. At the optimum braze thermal cycle, the mechanical test results achieved were a minimum of 80% and sometimes equivalent to that of the base metals properties.

ABS (Acrylonitrile Butadiene Styrene) is an industrially-important and widely used amorphous thermoplastic on which billions of dollars are spent annually in USA. Its applications cover impact-mitigation, infrastructural and laboratory piping systems, sports goods, musical instruments, automotive trim components and bumper bars, medical devices, enclosures, protective headgear, marine craft, luggage, domestic appliances, toys, consumer goods, edgings for industrial goods, etc. Its use to contain impact damage is primary; hence continued research in this area is warranted. The novelty and contribution of this work lies in its employment of more deeply insightful parameters and methods of characterization in acoustic emission and ultrasonics, as well as advanced optical microstructural characterization with sophisticated instrumentation, on one hand, and the wider correlations and conclusions now made possible by these means. In the work which this paper reports, the impact response behavior of ABS material under various levels of impact energy was investigated using results obtained from the mechanical test, and parameters obtained from non-destructive test methods such as Acoustic Emission (AE), Ultrasonics, and Optical Inspection. The ABS plates were impacted by a hemispherical steel projectile in a drop-weight impact tester. Two AE sensors were placed on the surfaces of ABS plates during the impact tests. After the impact tests were completed, ultrasonic C-Scan investigation of the damaged areas was also carried out, and sections were inspected under the microscope. Correlations between damage areas and various parameters of the non-destructive diagnostic test methods utilized were explored. ABS is one of the most highly impact-resistant materials utilized in industry. Its characterization under impact is therefore very important, in order to devise ways of enhancing properties that would make the material or structures made from it, better in service. In this work, plate samples of rectangular shape were subjected to central impacts from a spherical impactor released from various heights. It is of interest to know how the impact propagates through the plate thickness, and how the microstructure is affected from point to point, both laterally and depth-wise. The issues of energy transfer and dissipation are significant in terms of the effectiveness of the material as an impact deadener. Three non-destructive methods are utilized in this work for comprehensiveness and effectiveness. The AE approach is broadly divisible into two — classical, and transient. The former has dozens of descriptive parameters per each of the three dimensions, while the latter, which is based on the waveform and its several possible transforms, adds even many more possibilities. Thus, characterization in AE is particularly rich, and, when a sufficient number of appropriate parameters are utilized, has a very high probability of correctly depicting what is really going on in the material or structure under inspection. The ultrasonic scan reveals in color-code the variation of the material homogeneity throughout the scanned space, which, in each case, covered the whole plate. This normally provides a good picture of damage and its intensity variation in the test piece. The microstructure of selected parts of the test pieces before and after impact was inspected with a violet laser microscope. In this instrument, reflecting light from the white light source is detected with a color CCD camera. This camera obtains color information at the peak (focal point) detected with the laser light source on a pixel basis, thus enabling a real color examination, which SEMs cannot do. This instrument also uses a pin hole confocal optical system which enables high accuracy measurement and high definition examination by eliminating reflecting light from points other than the peak. The results obtained showed clear relationships between energy and geometrical and material metrics of damage through the damage zone and shed more light on possible pathways to the desired enhancement of impact resistance in this case.

Abstract Industries rely mostly on off-shore resources to fulfill the increase in demand for oil and gas. In general, for oil extraction and various other refinery processes, fixed or floating structures are being utilized. Floating Production Storage and Offloading (FPSO) system is one of the floating systems which have advantage of storing the crude oil and, if required, it can be easily moved to other places. Also, in deep Ocean where sub-sea pipeline infrastructures are often not possible and so the FPSOs give alternate option of storing and processing the crude oil. Being moored-systems, FPSOs are very flexible structures having high surge natural period and hence they may undergo larger surge displacement. Excessive displacement may cause damage for the riser system also it may affect the workability under extreme sea condition. Therefore, there is a need for investigating the issues of safety, efficiency and response control of FPSO systems under different sea-state conditions. Ocean wave loads on FPSO causes dynamic interaction between FPSO vessel and liquid in the oil storage containers. The liquid motion in containers disturbs the dynamics of the vessel significantly. Hence, it is essential to study the surge response control of FPSO in detail. An easy way to control the response is to use the existing cargo containers of FPSO as passive damping devices. If the natural frequency of liquid oscillation is tuned to the natural frequency of FPSO, these cargo tanks can act as Multiple Tuned Liquid Dampers (MTLDs). In case of simple linear model, Tuned liquid damper (TLD) can be idealized as a Single Degree of Freedom (SDOF) system, namely Tuned Mass Damper (TMD). The present study attempts to model a TLD using three different TMD systems to account the effects of shallow water sloshing.

Abstract Water contaminated with phenols is produced from several oil and gas related industries. Although there are a number of treatment methods, enzymatic wastewater treatment is more attractive due to its sustainability, environmental-friendliness, and mild nature. A key limitation of this process, however, is the enzymatic deactivation (whether complete or partial) during the treatment process. This limitation might be addressed to a certain extent through the addition of biosurfactants to the reaction medium. Thus, the key aim of this study is to utilize laccase (an oxidoreductase enzyme from Trametes versicolor) to remove bisphenol A (BPA) from wastewaters in the presence of rhamnolipid biosurfactant. Since most wastewaters contain inorganic salts, the efficacy of enzymatic treatment of high saline wastewaters has been evaluated. The beneficial effect of the biosurfactant addition during the enzymatic treatment of highly saline phenolic wastewater has been also assessed. Additionally, the effect of increasing the biocatalyst and the phenolic pollutant concentrations have been also probed. The results showed that the BPA degradation rate increases with increasing the enzyme concentration. The extent of BPA removal also increased with increasing the biocatalyst concentration, approaching almost a complete removal at an enzyme concentration of 400 ppm. The BPA degradation rate also increased almost linearly with increasing its initial concentration; however, its removal extent showed the opposite trend. The addition of as low as 1 ppm rhamnolipid biosurfactant to the reaction medium increased both the BPA degradation rate and the removal extent relative to the biosurfactant-free wastewater samples. The addition of the biosurfactant to the reaction medium boosted the BPA degradation rate and the removal extent by 1.1- to 1.23-fold. The highest BPA degradation rate and removal enhancement (about 23% higher than those in the absence of the biosurfactant) was obtained for BPA-rhamnolipid mass ratio of 50:1. The presence of salt severely reduced the BPA degradation rate and removal. The addition of 20 mM NaCl resulted in about 1.7-fold drop in the BPA degradation rate and removal. The drop in the BPA degradation rate and removal reached more than 3.6-fold at 500 mM NaCl. The addition of 1 ppm rhamnolipid partially compensated the negative effect of salinity, providing relatively higher BPA degradation rate and removal at all examined salinity levels. The findings reported herein reveal the positive effect of biosurfactant addition to the enzymatic reaction medium and the need for the salt removal prior to subjecting the saline wastewaters to enzymatic treatment.