Selection and Design of Brazing Fillers for Metal-Ceramic Joints

2007 ◽  
Vol 539-543 ◽  
pp. 4008-4012 ◽  
Author(s):  
Vinzenz Bissig ◽  
Jolanta Janczak-Rusch ◽  
Matteo Galli
Keyword(s):  
Residual Stresses ◽  
Filler Metal ◽  
Single Layer ◽  
Dissimilar Materials ◽  
Processing Temperature ◽  
Bend Strength ◽  
Key Factors ◽  
Brazing Fillers ◽  
Active Filler ◽  
Selection Of

Three different approaches for metal to ceramic brazing are compared using the example of Si3N4/TiN-steel joints: the use of an active filler metal (single layer brazing system), the metallisation of the ceramic and brazing with a non active filler (two-layer brazing system), the use of a composite brazing filler system (three layer brazing system). Different aspects are analysed: the development of the joint’s microstructure in the as-brazed state, the thermally induced residual stresses and the resulting bend strength of the joint’s strength. With two layers and three layers brazing system, bend strength of about 400 MPa, about 15% higher then single filler metal, were achieved. The three layer brazing system has two advantages: firstly one step processing secondly lower scattering of joint bend strength compared to two layers brazing system. The key factors in all cases are the selection of the brazing fillers and the braze design. In all cases a careful selection of the brazing fillers and the braze design are the key factors. The first criteria for the selection of the brazing fillers for joints of dissimilar materials can be done by considering only the main filler characteristics like titanium content, processing temperature and yield stress. It’s necessary to simulate the joint behaviour by finite element simulation for verifying the final selection of filler metals. It was clearly seen that the plasticity of the filler metal is the main factor affecting residual stresses for the joint geometry in this current work.

scholarly journals Effect of Interface Microstructure on Joint Strength of Zirconia/Titanium Alloy Brazed with Amorphous Zr-Ti-Ni-Cu Active Filler Metal

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 718
Author(s):  
Sung Woo Park ◽  
Hyunjong Lee ◽  
Byung Hoon Lee ◽  
Tae Hwan Kim ◽  
Kyung Il Kim ◽  
...  
Keyword(s):  
Joint Strength ◽  
Filler Metal ◽  
Intermetallic Phases ◽  
Metallic Alloys ◽  
Filler Alloy ◽  
Interface Microstructure ◽  
Processing Conditions ◽  
Active Filler ◽  
Island Type ◽  
Selection Of

Active brazing of zirconia with metallic alloys is a promising method for enhancing the mechanical property of zirconia. However, the brazing process of zirconia and metallic alloys has not been studied in detail because of a limitation in selection of materials and processing conditions. Here, we successfully brazed zirconia with Ti-3Al-2.5V alloy using amorphous Zr54Ti22Ni16Cu8 active filler alloy. By manipulating the brazing temperature from 800 °C to 860 °C, a highest strength of ~186 MPa was achieved at 860 °C. Reduced brittle (Zr,Ti)2(Ni,Cu) intermetallic phases from formation of island-type (Zr,Ti) matrix, ZrO2-X, TiO, and TiO2 interlayer play a key role in increasing the joint strength. Our findings will be helpful in developing brazing processes for zirconia and metallic alloys.

HAYNES 230-W FILLER WIRE

Alloy Digest ◽  
2000 ◽  
Vol 49 (2) ◽  
Keyword(s):  
Physical Properties ◽  
Filler Metal ◽  
Filler Wire ◽  
Bend Strength ◽  
Haynes 230

Abstract Haynes 230-W Filler Wire is a specially formulated welding filler metal designed for the fabrication of Haynes 230 alloy (see Alloy Digest Ni-320, August 1985). This datasheet provides information on composition, physical properties, elasticity, and bend strength. It also includes information on joining. Filing Code: Ni-558. Producer or source: Haynes International Inc.

The overview of existing knowledge on medical cannabis plants growing  

2021 ◽  
Author(s):  
Matěj Malík ◽  
Jiří Velechovský ◽  
Pavel Tlustoš
Keyword(s):  
Plant Nutrition ◽  
Modern Medicine ◽  
Essential Elements ◽  
Pharmaceutical Sciences ◽  
Medical Cannabis ◽  
Key Factors ◽  
Factors Affecting ◽  
Cultivation Technology ◽  
Active Substances ◽  
Selection Of

The use of cannabis for medicinal purposes dates back well before the era of modern medicine, but in recent years research into the use of medical cannabis in the medical and pharmaceutical sciences has grown significantly. In European countries, most cannabis plants have been and still are grown for industrial purposes. For this reason, hemp cultivation technology is relatively well researched, while little is known about the key factors affecting cannabis cultivation for medical purposes. The active substances of cannabis plant targeted by this review are called phytocannabinoids. The biosynthesis of phytocannabinoids is relatively well understood, but the specific environmental factors that influence the type and number of phytocannabinoids have been much less studied. Indoor or greenhouse cultivation, which uses automated lighting, ventilation, irrigation systems and complex plant nutrition has become much more sophisticated and appears to be the most effective method for producing medical cannabis. There are many different cultivation systems for cannabis plants, but one of the essential elements of the process is an optimal plant nutrition and selection of fertilisers to achieve it. This review summarises the existing knowledge about phytocannabinoid biosynthesis and the conditions suitable for growing plants as sources of medical cannabis. This review also attempts to delineate how nutrient type and bioavailability influences the synthesis and accumulation of specific phytocannabinoids based on contemporary knowledge of the topic.  

Opportunity zones: Do tax benefits go to the most distressed communities?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
James R. Barth ◽  
Yanfei Sun ◽  
Shen Zhang
Keyword(s):  
African American ◽  
Family Income ◽  
Tax Incentives ◽  
Poverty Rate ◽  
Key Factors ◽  
Median Family Income ◽  
Content Type ◽  
Explanatory Factors ◽  
Tax Benefits ◽  
Selection Of

Purpose The exact criteria used by state governors for choosing opportunity zones (OZs) are not publicly available. This paper aims to examine whether state governors selected the most distressed communities, or those with the highest proportions of minorities, as OZs. Design/methodology/approach This paper compares the distressed communities chosen as OZs in states throughout the country to an equal number of those eligible distressed communities but not selected. Moreover, this paper uses regression analysis to determine whether the poverty rate, median family income, population, percentage of population that is minority and the percentage of population that is African American are significant explanatory factors in the choice of OZs. Findings After describing the tax incentives for investing in OZs, this paper documents that governors did not select many of the most distressed communities, or those with high proportions of minorities, in their individual states. Originality/value This paper describes in some detail the way in which investors may generate tax benefits by investing in eligible property or businesses in OZs. It also examines the extent to which the degree of poverty and the percentage of the population that is minority (and African American) were key factors in the selection of OZs. It arises an issue that the chosen communities are not necessarily those most in need of more investment or those heavily populated by minorities, particularly African Americans.

PREDICTION OF PEEK RESIN PROPERTIES FOR PROCESSING MODELING USING MOLECULAR DYNAMICS

2021 ◽  
Author(s):  
KHATEREH KASHMARI ◽  
PRATHAMESH DESHPANDE ◽  
SAGAR PATIL ◽  
SAGAR SHAH ◽  
MARIANNA MAIARU ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Residual Stresses ◽  
Crystallization Kinetics ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Processing Parameters ◽  
Thermomechanical Properties ◽  
Volumetric Shrinkage ◽  
Processing Temperature ◽  
Wide Range

Polymer Matrix Composites (PMCs) have been the subject of many recent studies due to their outstanding characteristics. For the processing of PMCs, a wide range of elevated temperatures is typically applied to the material, leading to the development of internal residual stresses during the final cool-down step. These residual stresses may lead to net shape deformations or internal damage. Also, volumetric shrinkage, and thus additional residual stresses, could be created during crystallization of the semi-crystalline thermoplastic matrix. Furthermore, the thermomechanical properties of semi-crystalline polymers are susceptible to the crystallinity content, which is tightly controlled by the processing parameters (processing temperature, temperature holding time) and material properties (melting and crystallization temperatures). Hence, it is vital to have a precise understanding of crystallization kinetics and its impact on the final component's performance to accurately predict induced residual stresses during the processing of these materials. To enable multi-scale process modeling of thermoplastic composites, molecular-level material properties must be determined for a wide range of crystallinity levels. In this study, the thermomechanical properties and volumetric shrinkage of the thermoplastic Poly Ether Ether Ketone (PEEK) resin are predicted as a function of crystallinity content and temperature using molecular dynamics (MD) modeling. Using crystallization-kinetics models, the thermo-mechanical properties are directly related to processing time and temperature. This research can ultimately predict the residual stress evolution in PEEK composites as a function of processing parameters.

scholarly journals Effect of Residual Stresses of GTA Welding for Dissimilar Materials

2018 ◽  
Vol 21 (4) ◽  
Author(s):  
Harinadh Vemanaboina ◽  
Gundabattini Edison ◽  
Suresh Akella ◽  
Ramesh Kumar Buddu
Keyword(s):  
Residual Stresses ◽  
Dissimilar Materials ◽  
Gta Welding

scholarly journals Why We Go Where We Go: Profiling User Decisions on Choosing POIs

2020 ◽  
Author(s):  
Renjun Hu ◽  
Xinjiang Lu ◽  
Chuanren Liu ◽  
Yanyan Li ◽  
Hao Liu ◽  
...  
Keyword(s):  
Key Factors ◽  
Real World Data ◽  
Decision Factors ◽  
Point Of Interest ◽  
Learning Factor ◽  
Poi Recommendation ◽  
Key Factor ◽  
Selection Of ◽  
Decision Structures

While Point-of-Interest (POI) recommendation has been a popular topic of study for some time, little progress has been made for understanding why and how people make their decisions for the selection of POIs. To this end, in this paper, we propose a user decision profiling framework, named PROUD, which can identify the key factors in people's decisions on choosing POIs. Specifically, we treat each user decision as a set of factors and provide a method for learning factor embeddings. A unique perspective of our approach is to identify key factors, while preserving decision structures seamlessly, via a novel scalar projection maximization objective. Exactly solving the objective is non-trivial due to a sparsity constraint. To address this, our PROUD adopts a self projection attention and an L2 regularized sparse activation to directly estimate the likelihood of each factor to be a key factor. Finally, extensive experiments on real-world data validate the advantage of PROUD in preserving user decision structures. Also, our case study indicates that the identified key decision factors can help us to provide more interpretable recommendations and analyses.

Optimization of space-constrained micro-perforated absorbers by causality criteria

2021 ◽  
Vol 263 (6) ◽  
pp. 275-286
Author(s):  
Teresa Bravo ◽  
Cedric Maury
Keyword(s):  
Absorption Coefficient ◽  
Low Frequency ◽  
Single Layer ◽  
Optimization Procedure ◽  
Separation Distance ◽  
Physical Parameters ◽  
Total Absorption ◽  
Causality Criterion ◽  
Selection Of ◽  
Total Absorption Coefficient

The problem of space-constrained absorbers in the low frequency range constitutes an area of continuous research. Micro-perforated panels are advantageous because they can be tuned by a proper selection of their constitutive physical parameters including the diameter of the perforations and their separation distance, their thickness and the length of the backing cavity. However, such optimal selection is not straightforward, especially when considering multi-layer partitions. Current optimization algorithms are based on the maximization of the total absorption coefficient averaged over a frequency band, that requires a compromise between the bandwidth and the thickness of the control device. In this work, the problem is analysed on the basis of a causality criterion. This principle is generalized from its formulation in the field of electromagnetism to obtain a relation that correlates the thickness-to-bandwidth performance of a micro-perforated absorber to its total absorption coefficient. Using this relation, an optimization procedure is presented for the sequential selection of the optimal physical parameters for single-layer partitions. An excellent agreement has been found between the optimal values obtained by the causality criterion and those achieved by critical coupling conditions.

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