scholarly journals Microstructural characterization of white etching cracks in bearings after long-term operation in wind turbines

2021 ◽  
Vol 294 ◽  
pp. 129754
Author(s):  
H.K. Danielsen ◽  
C. Hong ◽  
O.V. Mishin
Keyword(s):  
Wind Turbines ◽  
Microstructural Characterization ◽  
Term Operation ◽  
White Etching Cracks

Serviceability Characterization of Composite Storage Tanks

2007 ◽  
Author(s):  
Vladimir M. Shkolnikov
Keyword(s):  
Structural Design ◽  
Design Procedure ◽  
Fatigue Properties ◽  
Storage Tanks ◽  
Safety Factors ◽  
Analytical Technique ◽  
Term Operation ◽  
Temperature Exposure

This paper outlines an analytical technique enabling serviceability characterization of a storage tank made of a Polymer Matrix Composite (PMC) with regards to a specified profile of long-term operation of the tank. The technique combines force-temperature exposure (conceivably changing over a tank’s service life) and fatigue properties of a composite utilized within the tank structure. Along with a serviceability assessment, the technique is capable of providing a well-grounded specification of design knock-downs and safety factors relevant to the conventional structural design procedure.

scholarly journals Phase and Microstructural Characterization of Lime-MK Blended Mixes

2012 ◽  
Vol 730-732 ◽  
pp. 135-140 ◽  
Author(s):  
André Gameiro ◽  
António Santos Silva ◽  
R. Veiga ◽  
Ana Velosa
Keyword(s):  
Microstructural Characterization ◽  
Pozzolanic Reaction ◽  
Material Degradation ◽  
Molar Ratios ◽  
Pozzolanic Reactivity ◽  
Pozzolanic Material ◽  
Granulated Blast Furnace Slag ◽  
Calcium Silicate Hydrates

Metakaolin (MK) is nowadays a well-known pozzolanic material used in cement-based materials. Its benefits are related to its great pozzolanic reactivity when compared with some others pozzolanic materials, like fly ash or ground-granulated blast furnace slag. When MK reacts with calcium hydroxide, cementitious products are formed. It is known that the main phases produced during its pozzolanic reaction at ambient temperature are calcium silicate hydrates (CSH), stratlingite (C2ASH8) and calcium aluminate hydrate (C4AH13). However, in literature there are several discrepancies regarding these phases stability, namely the transformation of stratlingite and C4AH13 into hydrogarnet (C3AH6) at long term. The consequences of that instability are a reduction in the porosity and a loss of microstructural strength that can induce a complete material degradation. The MK is a material with great potential in Portugal, since there is a large abundance of kaolinitic clays, however its development is not yet achieved. In order to answer this demand a research project was initiated with the aim of optimizing the production of MK in Portugal and enhancing the durability of aerial calcitic lime mortars, to be mainly used in conservation and restoration of historical buildings. With the objective of studying the compounds formed in lime/MK and their stability during time, we have prepared different lime/MK ratio pastes (molar ratios). These lime/MK pastes were stored at saturated conditions (RH > 95%) and 23 ± 2 °C temperature being analysed at several ages by TGA-DTA, XRD and SEM-EDS. In this paper the results obtained are presented and discussed.

scholarly journals Electrochemical and physical characterization of Ni-Cu-Fe alloy for chlor-alkali hydrogen cathodes

2003 ◽  
Vol 28 (2) ◽  
pp. 21-28 ◽  
Author(s):  
M. J. Giz ◽  
M. C. Marengo ◽  
E. A. Ticianelli ◽  
E. R. Gonzalez
Keyword(s):  
Low Ph ◽  
Physical Characterization ◽  
Energy Dispersive Analysis ◽  
Positive Aspect ◽  
X Ray ◽  
Term Operation ◽  
Different Temperatures ◽  
X Ray Absorption

This work describes the development of an alternative acetate bath for the electrochemical codeposition of Ni-Cu-Fe electrodes at low pH that is stable for several weeks and produces electrodes with good performance for chlor-alkali electrolysis. Physical characterization of the electrode surface was made using X ray absorption spectroscopy (XAS), scanning electron microscopy (SEM) and energy dispersive analysis (EDX). The evaluation of the material as electrocatalyst for the hydrogen evolution reaction (her) was carried out in brine solution (160 g L-1 NaCl + 150 g L-1 NaOH) at different temperatures through steady-state polarization curves. The Ni-Cu-Fe electrodes obtained with this bath have shown low overpotentials for the her, around 0.150 V at 353 K, and good stability under continuous long-term operation for 260 hours. One positive aspect of this cathode is that the polarization behavior of the material shows only one Tafel slope over the temperature range of 298 - 353 K.

Microstructural characterization of self-healing products in cementitious systems containing crystalline admixture in the short- and long-term

2021 ◽  
pp. 104369
Author(s):  
Aline de Souza Oliveira ◽  
Romildo Dias Toledo Filho ◽  
Eduardo de Moraes Rego Fairbairn ◽  
Luiz Fernando Cappa de Oliveira ◽  
Otávio da Fonseca Martins Gomes
Keyword(s):  
Microstructural Characterization ◽  
Self Healing ◽  
Short And Long Term ◽  
Cementitious Systems

Microstructural Characterization of NiCrFeSiBC Coating During Long-Term Isothermal Oxidation at 850 °C

2019 ◽  
Vol 28 (6) ◽  
pp. 1275-1283
Author(s):  
Alexandra Banu ◽  
Maria Marcu ◽  
Oana Trusca ◽  
Alexandru Paraschiv ◽  
Elena Maria Anghel ◽  
...  
Keyword(s):  
Microstructural Characterization ◽  
Isothermal Oxidation

Characterization of Thick Film Technology for 300°C Packaging

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000097-000107 ◽  
Author(s):  
Rui Zhang ◽  
R. Wayne Johnson ◽  
Vinayak Tilak ◽  
Tan Zhang ◽  
David Shaddock
Keyword(s):  
Thick Film ◽  
Analog Circuits ◽  
Passive Components ◽  
Term Operation ◽  
C Storage ◽  
Selection Of ◽  
Device Technology ◽  
Thick Film Technology

Geothermal well logging and instrumentation applications require electronics capable of 300°C operation. SiC device technology enables the design and fabrication of analog circuits that can operate at these temperatures. However, to build functional circuits, an interconnection and packaging technology must be demonstrated to provide interconnectivity between different SiC devices and passive components. For long-term operation, organic based packaging is limited to ∼250°C with careful selection of materials. Thick film technology based on ceramics and metals has potential for higher operating temperatures. In this work the effect of 300°C storage on the adhesion of different thick film Au conductors and a multilayer dielectric have been studied. In addition, the electrical properties of the dielectric have been studied as a function of temperature and of high temperature aging. Assembly technologies: component attach, wire bonding and external lead attach have also been investigated and the results are reported.

Characterization of LTCC-Thick Film Technology for 300°C Packaging

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000046-000051 ◽  
Author(s):  
Tan Zhang ◽  
David Shaddock ◽  
Alexey Vert ◽  
Rui Zhang ◽  
R. Wayne Johnson
Keyword(s):  
Thick Film ◽  
Reservoir Characterization ◽  
Temperature Cycling ◽  
Potential Candidate ◽  
Term Operation ◽  
Die Attach ◽  
Functional Analog ◽  
Thick Film Technology

Economic geothermal well construction and reservoir characterization requires high temperature logging tools and sensors with the long-term operation capability of 300°C. Low temperature co-fired ceramic (LTCC) and thick film technology make them a potential candidate for building interconnects to SiC device and functional analog or digital circuits to operate at that temperature. In this work, single conductor layer LTCC substrates have been fabricated to characterize the thick film Au adhesion under 300°C aging. Via reliability has been evaluated on the multi-layer LTCC substrates under temperature cycling of 35–325°C. In addition, die attach, wire bonding and stud bumping assembly techniques has been investigated.

Effect of Heat Treatment on the Corrosion Resistance of Cast Mg-7.3Al Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 585-588
Author(s):  
Su Qiu Jia ◽  
Guo Jun Liu ◽  
Qi Shuang Chen
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Microstructural Characterization ◽  
Main Role ◽  
Β Phase

Mg-7.3Al magnesium alloys were investigated in the paper. The paper presents microstructural characterization of Mg-7.3Al alloy after casting and heat treatment. The casting temperature was 740°C and heat treatment was performed at 420 °C for 24 h with aging at 180 °C for 8h,16h,24h. The microstructure of the casting alloy consists of α-Mg phase matrix with a primary β phase (Mg17Al12) at grain boundaries. After solution treatment β phases were soluted in α-Mg phase matrix . Aging treatment caused β phases precipitation. The corrosion resistance of magnesium alloy was determined in 3.5 % NaCl by immersion tests and polarization curves. The results shows that the corrosion resistance of magnesium alloy after solution treat is the best than that of the others heat treatment in polarization curve tests and the samples with aging for 16h and 24h presents higher corrosion resistance than those with solution and aging for 8h in immersion tests. Solution treatment plays a main role for corrosion resistance of Mg-7.3Al magnesium alloy in short term corrosion, but more continuous β phases in Mg-7.3Al alloy after ageing act as a barrier and play a main role in long term corrosion.

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