scholarly journals Preparation and characterization of electroless Ni coated nano alumina powder under different sensitization - activation conditions

10.30544/467 ◽  
2020 ◽  
Author(s):  
Sameer Kumar Devarakonda ◽  
Naga Sai Suman K ◽  
Kalyana Krishna Y
Keyword(s):  
Alumina Powder ◽  
Metallic Ions ◽  
Nano Alumina ◽  
Characterization Studies ◽  
Electroless Coatings ◽  
Activation Conditions ◽  
Average Size ◽  
Electroless Ni

The development of electroless coatings on various substrates has gained much interest among researchers for the sake of improved properties. However, the coating on ceramic particles as a source of reinforcement is still a challenge for the researchers and requires a good comprehension of fundamentals since the coating thickness relies upon many parameters. Particularly the sensitization and activation conditions are more important for the creation of an ideal environment to draw metallic ions as a coating layer. Therefore, this paper examines the role of sensitization and activation conditions on the viability of nickel coating on the alumina particles of an average size of 50 nm. A comparison is made between two environments, namely individual and blended activations in the preparation of coated particles. Characterization studies are also presented to support the discussion. 

Synthesis and characterization of nano-alumina powder by milling of Al and MnO2 powder mixture

2021 ◽  
Author(s):  
K.S. Ravikumar ◽  
S. Ghanaraja ◽  
M.R. Ramesh
Keyword(s):  
Powder Mixture ◽  
Synthesis And Characterization ◽  
Alumina Powder ◽  
Nano Alumina

Elaboration and Mechanical Characterization of Al2O3-ZrO2-YAG Ultrafine Composites

2010 ◽  
Vol 62 ◽  
pp. 76-81 ◽  
Author(s):  
Paola Palmero ◽  
Valentina Naglieri ◽  
Giulia Spina ◽  
Laura Montanaro
Keyword(s):  
Mechanical Characterization ◽  
Alumina Powder ◽  
Nano Crystalline ◽  
Slip Cast ◽  
Second Phases ◽  
Crystalline Alumina ◽  
Inorganic Precursors ◽  
Full Densification

Al2O3-YAG-ZrO2 composites have been produced by surface modification of a commercial nano-crystalline alumina powder with inorganic precursors of the desired second phases. The doped powders were calcined at various temperatures and for different times: as a function of the thermal treatment, zirconia directly crystallized on the alumina surface, while YAG phase was yielded by solid state reaction among an amorphous yttrium-rich precursor and alumina powder. Several compositions, with increasing second phases volume fractions, were investigated, precisely, Alumina-5vol.%YAG-5vol.%ZrO2, Alumina-20vol.%YAG-20vol.%ZrO2 and Alumina- 33vol.%YAG-33vol.%ZrO. Slip cast bodies were produced by aqueous suspensions of calcined and well-dispersed powders; free-sintering performed at 1500°C for 3 h allowed to reach full densification. The role of the second phases amount on the microstructural features and on some mechanical data preliminary evaluated was established.

Tribological Characterization of Electroless Ni–B Coatings Formed on Commercial Purity Magnesium

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
E. Correa ◽  
J. F. Mejía ◽  
J. G. Castaño ◽  
F. Echeverría ◽  
M. A. Gómez
Keyword(s):  
Sliding Wear ◽  
Parametric Optimization ◽  
Commercial Purity ◽  
Electroless Coating ◽  
Friction Testing ◽  
Wear And Friction ◽  
Electroless Coatings ◽  
Tribological Characterization ◽  
Electroless Ni

Ni–B coatings have been deposited directly on commercial purity magnesium and evaluated by means of sliding wear and friction testing. The nickel and boron are distributed throughout the whole thickness of the coating. Parametric optimization has been carried out using the design of experiment based on Taguchi analysis. The friction coefficients of the coatings vary between 0.01 and 0.3, depending on the evaluated conditions. The lowest wear rate of the coating was 0.19 × 10−5 mm3 N−1 m−1. Wear and friction coefficient maps of Ni–B electroless coatings formed on magnesium surfaces are reported. Nanoparticles present in the lubricating fluid act as a third wear body increasing the wear of the electroless coating

scholarly journals Herd management information systems to support cattle population research: the VAMPP® case

2020 ◽  
pp. 141-156
Author(s):  
Z. Sánchez-Hernández ◽  
C. S. Galina-Hidalgo ◽  
B. Vargas-Leitón ◽  
J. Rojas-Campos ◽  
S. Estrada-König
Keyword(s):  
Information Systems ◽  
Population Level ◽  
Herd Size ◽  
Cattle Population ◽  
Population Research ◽  
Health Events ◽  
Daily Milk Production ◽  
Average Size

Introduction. Livestock information systems, besides being indispensable for the daily management of the herd, can serve as a basis for research at the population level. Objective.The objective of the study was to analyze the role of the VAMPP® system as a source of information for cattle population research over 32 years of evolution in Costa Rica. Materials and methods. A statistical analysis of the system database (VAMPP®) covering the period between 1987 and 2018 was carried out. Trends in the dissemination and adoption of the system were evaluated according to period, area, production system, and herd size. The use of information for the exploration of trends by breed and area was exemplified. The contribution of the system at the academy level and production of scientific literature was quantified. Results. 2285 herds (88.8 % specialized dairy and 11.2 % dual purpose) were counted with an average of 9.4±7.9 years of follow-up in the VAMPP® system. The areas with greater diffusion were the very humid premontane forest (29 %) and very humid tropical forest (25 %). The average size of the herd was 124±255 adult cows. The system contains records on 404 316 cows, mostly of Holstein (36.3 %), Jersey (24.6 %), and Holstein×Jersey (20.9 %) breeds. The database includes information on 1,249,557 calvings, 16,223,260 records of daily milk production, and 443,108 health events, predominantly related to mastitis (35.6 %) and laminitis (14.1 %). The system has been used for the elaboration of at least 74 investigations leading to academic degrees and the production of 71 scientific articles, mainly related to health and genetic issues. Conclusion. The information obtained from the VAMPP® system has allowed a detailed characterization of the productive performance of local dairy cattle.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Characterization of microwave-sintered ceramic composites

1993 ◽  
Vol 51 ◽  
pp. 1136-1137
Author(s):  
X. Zhang ◽  
Y. Pan ◽  
T.T. Meek
Keyword(s):  
Matrix Material ◽  
Maximum Output Power ◽  
Ceramic Matrix Composite ◽  
Ceramic Composites ◽  
Processing Technique ◽  
Structure Characterization ◽  
Alumina Powder ◽  
Maximum Output ◽  
Sintered Ceramic

Industrial microwave heating technology has emerged as a new ceramic processing technique. The unique advantages of fast sintering, high density, and improved materials properties makes it superior in certain respects to other processing methods. This work presents the structure characterization of a microwave sintered ceramic matrix composite.Commercial α-alumina powder A-16 (Alcoa) is chosen as the matrix material, β-silicon carbide whiskers (Third Millennium Technologies, Inc.) are used as the reinforcing element. The green samples consisted of 90 vol% Al2O3 powder and 10 vol% ultrasonically-dispersed SiC whiskers. The powder mixture is blended together, and then uniaxially pressed into a cylindrical pellet under a pressure of 230 MPa, which yields a 52% green density. The sintering experiments are carried out using an industry microwave system (Gober, Model S6F) which generates microwave radiation at 2.45 GHz with a maximum output power of 6 kW. The composites are sintered at two different temperatures (1550°C and 1650°C) with various isothermal processing time intervals ranging from 10 to 20 min.

Consideraciones en torno a la reducción solipsista

1970 ◽  
Vol 11 ◽  
Author(s):  
Natalia Carolina Petrillo

ResumenEn el presente trabajo se intentará mostrar que la fenomenología no conduce a una postura solipsista. Para ello, se caracterizará en qué consiste el solipsismo. Luego, se intentará refutar a lo que se ha de llamar “solipsismo metafísico” y “solipsismo gnoseológico”, con el objetivo principal de poner de manifiesto el fundamento de motivación para la salida de la ficción solipsista.Palabras claves:Phenomenology – solipsim – empatía - HusserlAbstractWith the aim of showing that phenomenology does not lead in solipsism, I will first attempt a characterization of it. Then, I will attempt a refutation of the so-called “metaphysical” and “epistemological” solipsisms. Finally, the nature and role of Husserl´s solipsistic fiction is examined, and the grounds that motivate the overcoming of this standpoint are disclosed.key wordsFenomenología – solipsismo - empathy – Husserl

ART STUDIOS – A WAY TO DEVELOPE CHILDREN’S IMAGINATION

2020 ◽  
Vol 11 (1) ◽  
pp. 144-148
Author(s):  
Liuba Zlatkova ◽  
Keyword(s):  
Fairy Tale ◽  
Psychological Effects ◽  
Complete Product ◽  
The Arts ◽  
The Creation ◽  
Role Of Parents

The report describes the steps for creating a musical tale by children in the art studios of „Art Workshop“, Shumen. These studios are led by students volunteers related to the arts from pedagogical department of Shumen University, and are realized in time for optional activities in the school where the child studies. The stages of creating a complete product with the help of different arts are traced – from the birth of the idea; the creation of a fairy tale plot by the children; the characterization of the fairy-tale characters; dressing them in movement, song and speech; creating sets and costumes and creating a finished product to present on stage. The role of parents as a link and a necessary helper for children and leaders is also considered, as well as the positive psychological effects that this cooperation creates.

Sign in / Sign up

Export Citation Format

Share Document