Wide Gap Braze Repair Using Vertically Laminated Repair Scheme

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Doug Nagy ◽  
Xiao Huang
Keyword(s):  
Life Cycle ◽  
Intermetallic Compounds ◽  
Life Cycle Cost ◽  
Historical Development ◽  
Braze Alloy ◽  
The Other ◽  
Laminated Structure ◽  
Considerable Saving ◽  
The Past ◽  
Wide Gap

Repair of after-service gas turbine hot section superalloy components provides considerable saving in life-cycle cost of engines. Whereas a number of methods have been used in the past to repair these superalloy components, wide gap brazing technology has provided a practical alternative to repair difficult-to-weld alloys with substantial damages. In this paper, the historical development of wide gap repair technologies is reviewed first. Subsequently, the recent development in utilizing a vertically laminated structure to repair a large and deep gap (up to 16 mm) in one brazing cycle will be discussed. The microstructure resulted from this repair scheme will be evaluated and compared with conventional wide gap braze with slurry and that of the Liburdi powder metallurgy (LPM™) process. It is observed that in conventional wide gap brazing with premixed slurry, the presence of intermetallic compounds can be effectively reduced by reducing the ratio of braze alloy to gap filler, which, however, also contributes to the increased occurrence of macroscopic voids in the wide gap joint. The LPM™ method, on the other hand, can achieve a macroscopically void-free repair of gap (up to 6 mm) and minimize the formation of intermetallics. By using a vertically laminated repair scheme it is shown that the process is able to repair a deeper gap (up to 16 mm) with no macroscopic defects and reduced intermetallic compounds.

Wide Gap Braze Repair Using Vertically Laminated Repair Scheme

2008 ◽  
Author(s):  
Doug Nagy ◽  
Xiao Huang
Keyword(s):  
Life Cycle ◽  
Intermetallic Compounds ◽  
Life Cycle Cost ◽  
Historical Development ◽  
Braze Alloy ◽  
The Other ◽  
Laminated Structure ◽  
Considerable Saving ◽  
The Past ◽  
Wide Gap

Repair of after-service gas turbine hot section superalloy components provides considerable saving in life-cycle cost of engines. Whereas a number of methods have been used in the past to repair these superalloy components, wide gap brazing technology has provided a practical alternative to repair difficult-to-weld alloys with substantial damages. In this paper, the historical development of wide gap repair technologies is reviewed first. Subsequently, the recent development in utilizing vertically laminated structure to repair large and deep gap (up to 16 mm) in one brazing cycle will be discussed. The microstructure resulted from this repair scheme will be evaluated and compared to conventional wide gap braze with slurry and that of LPM™ process. It is observed that in conventional wide gap brazing with premixed slurry, the presence of intermetallic compounds can be effectively reduced by reducing the ratio of braze alloy to gap filler which however, also contributes to the increased occurrence of macroscopic voids in the wide gap joint. The LPM™ method, on the other hand, can achieve a macroscopically void-free repair of gap (up to 6 mm) and minimize the formation of intermetallics. By using a vertically laminated repair scheme it is shown that the process is able to repair a deeper gap (up to 16 mm) with no macroscopic defects and reduced intermetallic compounds.

VERIFICATION OF REPAIR PAINTING EFFECT OF CORRODED WEATHERING STEEL BY EXPOSURE TEST

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Yuka Sugiyama ◽  
Toshihiko Aso ◽  
Atsumi Imai ◽  
Hiroaki Matsumoto
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Steel Surface ◽  
Steel Bridges ◽  
The Other ◽  
Weathering Steel ◽  
Water Leakage ◽  
Exposure Test ◽  
Repair Technique ◽  
Organic Zinc

Weathering steel generates dense protective rust on the steel surface. Since this protective rust would reduce corrosion speed, weathering steel can be used without any painting. Furthermore, the Life Cycle Cost of unpainted steel bridges would be lower than ordinary painted steel bridges. Due to these advantages, many weathering steel bridges have been constructed in recent years. Unfortunately, the generation of anomalous rust has been reported in some bridges, cause of water leakage or deicer. It is necessary to repair these bridges, but the repair technique for corroded weathering steel has never been established yet. This study aims to clarify the effect of various repair painting for corroded weathering steel by performing an exposure test. The exposure test has been carried out from September 2015 to Okinawa and Yamaguchi. Test in Okinawa is supplied airborne salt, and the test in Yamaguchi is not supplied airborne salt. Specimens, which produced anomalous rust, were repaired by 19 methods and exposed. As a result, it is effective to repair by organic zinc-rich paint in the area with airborne salt. On the other hand, it is appropriate to remove rust and salt on the steel surface by blasting in the area which is not supplied airborne salt.

scholarly journals The ʿUbāda B. al-Ṣāmit Tradition at the Crossroads of Methodology

1970 ◽  
Vol 11 ◽  
pp. 137-235
Author(s):  
Pavel Pavlovitch
Keyword(s):  
Transmission Line ◽  
Historical Development ◽  
The Other ◽  
Literary Analysis ◽  
Considerable Part ◽  
Islamic History ◽  
Historical Material ◽  
The Past ◽  
Degree Of Acceptance ◽  
The Relationship

During the past few decades Western studies of the origin of Islam have made considerable advances in assessing sources which have long been considered a repository of exegetic, legal and historical material about the first centuries of Islam. Growing scepticism towards the Islamic foundation narratives and the traditional accounts of Islamic history undermined the notion that, unlike other religions, Islam “was born in the full light of history” and “its roots are on the surface” (A. Renan). The study of the first centuries of Islam has thus become the focus of clashing methodologies, often yielding conflicting accounts on how, when and where Islam emerged. While studying Muslim traditions (ḥadīths), Western Islamicists expressed varying opinions about reliability of lines of narrative transmission (isnāds), which, according to the traditional Muslim view, control the authenticity of the information included in the substantive part of the tradition (matn). One pole of the spectrum is represented by scholars who reject the link between the isnād and the matn. For them, the isnād is a fictitious authentication device that does not give any information about the historical development of the narrative. These scholars prefer to study the relationship between topically affiliated narratives, whence they derive information about the chronological development of the concepts conveyed by these narratives (literary analysis). The other part of the spectrum varies in the degree of acceptance of the isnāds. Nevertheless, these scholars generally agree that, provided certain methodological stipulations are met, a considerable part of the transmission line is authentic and correctly represents the ways through which the traditions were transmitted. With certain qualifications, the method of scholars who accept the isnād may be described as isnād-cum-matn analysis. In this article, I study the famous ʿUbāda tradition dealing with the punishment for adultery and fornication (zinā). First, I follow the historical development of the tradition by means of literary analysis. Then I apply to the same tradition the principles of isnād-cum-matn analysis. Although different in their treatment of the ḥadīth material, the two approaches are shown as capable of yielding results that are not mutually exclusive.

Effect of Ruthenium, Rhenium and Yttria Additions on the Microstructure of Wide Gap Brazing of IN738

2007 ◽  
Author(s):  
Xiao Huang ◽  
Scott Yandt ◽  
Doug Nagy ◽  
Matthew Yao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Life Cycle Cost ◽  
Filler Metal ◽  
Braze Alloy ◽  
Cost Effective ◽  
Brazed Joints ◽  
Brazed Joint ◽  
Wide Gap ◽  
Boride Phases

Modern gas and steam turbine components are subject to severe thermomechanical loads and extremely high temperature in order to provide increased performance and efficiency. Most high temperature turbine components are made of superalloys specifically developed for high temperature and high mechanical stress applications but at considerable cost. Defects may occur during manufacturing of superalloy castings as well as after service. Repair of these components, rather than replacement, helps to reduce the life cycle cost. Wide gap brazing is a cost effective and reliable means to repair gas turbine hot section components with defect sizes exceeding 0.3 mm. With proper control of the braze alloy and brazing cycle, the repaired region has been reported to posses mechanical properties approaching that of the parent materials. In order to further improve the mechanical properties of the repaired region and to explore the possibility of employing the wide gap brazing method to repair single crystal components in the future, three alloying additions, Ruthenium (Ru), Rhenium (Re) and yttria (Y2O3), were incorporated into the braze filler metal by mechanical alloying. The microstructures of the wide gap brazed joints with Ru, Re and yttria additions were studied and compared to a braze joint with standard wide gap braze alloys of IN738 and AWS BNi-9. It has been found that two types of borides formed in all braze alloys, namely eutectic γ-Ni-rich and boride phases and discrete boride containing primarily Cr and W (or Ru). The addition of Ru to the filler metal did not seem to modify the microstructural constituents after brazing. However, Ru partitioned strongly to the discrete borides. No isolated elemental Ru region was observed. On the other hand, Re addition was found to change the occurrence and distribution of both types of borides. The eutectic boride constituent was significantly reduced and finer discrete boride particles were observed. The addition of yttria did not change the boride formation but led to the generation of more voids in the brazed joint.

scholarly journals THE SEMANTIC CHANGES IN THE VOCABULARY(ON THE BASIS OF THE RUSSIAN AND AZERBAIJANI LANGUAGES)

HOMEROS ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 97-104
Author(s):  
Sevinj MAHARRAMOVA
Keyword(s):  
Historical Development ◽  
The Other ◽  
Slavic Languages ◽  
The Past ◽  
Part Of Speech ◽  
Concrete Part ◽  
Lexical Items ◽  
Modern Russian

The article deals with the analysis of the semantic changes in the vocabularies of the Russian and Azerbaijani languages caused by the influence of the different factors. Semantic archaisms are systematized according their belonging to the concrete part of speech (nouns, adjectives, verbs) and given in the appropriate tables. The reasons of the semantic changes during the historical development of the language are explained. Some Russian semantic archaisms are still used in the other Slavic languages (Ukrainian, Polish, Serbian). The historical excursus is carried out in the article, as necessary. So though the meanings of the Russian and Azerbaijani words considered in the article are archaic they are preserved in the structure of the modern words and might be relevant to the specific fields. They are used as terms in the different fields of science, they are preserved in the dialects, folklore. They are also important components of idioms, proverbs, sayings as they are relics of the past retained in the modern Russian and Azerbaijani languages. They have their own characteristics that makes them unique lexical items. Research of such semantic changes caused by the different factors is very interesting and significance both from the linguistic and historical standpoints.

scholarly journals Identifying Research Topics and Trends in Asset Management for Sustainable Use: A Topic Modeling Approach

2021 ◽  
Vol 13 (9) ◽  
pp. 4792
Author(s):  
Hosang Jung ◽  
Boram Kim
Keyword(s):  
Life Cycle ◽  
Asset Management ◽  
Topic Modeling ◽  
Life Cycle Cost ◽  
Latent Dirichlet Allocation ◽  
Sustainable Use ◽  
Future Research ◽  
Research Topics ◽  
The Past ◽  
Modeling Approach

Asset management is not new, and research has been conducted in private and public sectors on how to systematically maintain infrastructure or facilities for sustainable use and achieve the level of service desired by users or customers at the lowest life cycle costs. This research identifies the research topics and trends in asset management over the past 30 years. To this end, latent Dirichlet allocation, a topic modeling approach, was applied to articles published in engineering journals and investigated the following three research questions: (1) what have the key topics been for the past three decades? (2) what are the main activities and target sectors of asset management? (3) how have the research topics and keywords changed over the past three decades? The analysis shows that the target field of asset management has broadened while the main activities of asset management have been limited to several popular activities such as life cycle cost analysis and reliability analysis. Some implications and future research directions are also discussed.

A Comparative Study of China and America's Building Life Cycle Cost Database Establishment

2014 ◽  
Vol 935 ◽  
pp. 106-111
Author(s):  
Hao Xie ◽  
Jing Wu ◽  
Jibril Danazumi Jibril
Keyword(s):  
United States ◽  
Life Cycle ◽  
Construction Industry ◽  
Life Cycle Cost ◽  
The United States ◽  
Positive Influence ◽  
The Past ◽  
Key Issues ◽  
Building Life Cycle ◽  
The Cost

Life Cycle Cost (LCC) theory and method have a very positive influence on popularizing energy-saving of green buildings technology and reducing buildings energy consumption. However, applying LCC method into the construction industry field must be based on adequate and accurate data. In establishing the cost database of building LCC, America walks in the forefront of the world. Although China's building LCC cost database has been rapidly developed in the past few years, there is still a large gap between China and the United States. By comparing and analysing the establishment of building LCC cost database of the two countries-United States and China, this article indicates the key issues should be solved to build and further improve the Chinese future building LCC cost database, as well as give some relevant advice.

scholarly journals Life Cycle Cost Management of Concrete Structures

2018 ◽  
Author(s):  
José Matos ◽  
Anders Solgaard ◽  
Poul Linneberg ◽  
Alfred Strauss ◽  
Irina Stipanovič ◽  
...  
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
State Of The Art ◽  
Background Information ◽  
Uncertain Information ◽  
The Past ◽  
Analysis Methodology ◽  
Standards And Guidelines ◽  
Guidelines And Standards ◽  
Definition Of

Tools, guidelines and standards for assessment of Life Cycle Cost (LCC) of built environment e.g. buildings, infrastructure assets etc. have gained impact over the past years. Owner and operator application of tools, guidelines and standards enhances optimization of operation and maintenance with due respect to their budgets. In order to aid owners, operators and their designers, a task group under fib has been established to prepare a state-of-the-art report regarding LCC analyses of concrete assets. The state-of-the-art report contains a description of existing LCC standards and guidelines, their applicability, the definition of different cost elements, and the treatment of uncertain information in a reliability or risk based framework, etc. providing the reader with background information and methodology for preparation of such analysis. Moreover, the report contains case studies, presenting the applicability of the LCC analysis methodology.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Applications of Through-Focus Dark Field Image Shifts to Phase Identification

1975 ◽  
Vol 33 ◽  
pp. 178-179
Author(s):  
Prakash Rao
Keyword(s):  
Dark Field Image ◽  
Thin Foil ◽  
Dark Field ◽  
The Other ◽  
Stereo Image ◽  
Phase Identification ◽  
The Past ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Recent Extension

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.

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